Title of Invention	"STARTER FOR AN INTERNAL COMBUSTION ENGINE WITH A FREE-WHEEL STARTER HEAD"
Abstract	A starter motor including an electric motor (11) mechanically coupled to a starter (26) including a driver (33), a hitch member (45) for hitching the pinion (32) to the driver (33) via a free-wheel mechanical coupling (34) in the form of a friction clutch, and a priming spring (R1) built into the starter (26) between the hitch member (45) and the driver (33), whereby the two friction surfaces (37, 40) are spaced apart when the friction clutch is in the inoperative position, and a resisting torque is frictionally generated to enable reliable priming of the self-locking function

Title of Invention

"STARTER FOR AN INTERNAL COMBUSTION ENGINE WITH A FREE-WHEEL STARTER HEAD"

Abstract

A starter motor including an electric motor (11) mechanically coupled to a starter (26) including a driver (33), a hitch member (45) for hitching the pinion (32) to the driver (33) via a free-wheel mechanical coupling (34) in the form of a friction clutch, and a priming spring (R1) built into the starter (26) between the hitch member (45) and the driver (33), whereby the two friction surfaces (37, 40) are spaced apart when the friction clutch is in the inoperative position, and a resisting torque is frictionally generated to enable reliable priming of the self-locking function

Full Text	Starter, in particular for a motor vehicle, equipped with a friction-driven free-wheel starter head Technical field of the invention The invention relates to a starter for an internal combustion engine, in particular for a motor vehicle, provided with a flywheel with a toothed starting ring, comprising an output shaft provided with teeth, a starter head, a pinion belonging to the starter head, an electric motor for rotationally driving the output shaft mechanically coupled to the starter head mounted for axial sliding on the output shaft between a rear idle position and a front position of meshing of the starter head pinion with the toothed starting ring on the flywheel of the internal combustion engine, the said starter head comprising: - a driver controlled by a means of control between its rear and front positions and equipped with drive flutes in engagement with the complementary teeth of the output shaft, - a piece coupling the pinion to the driver by means of a mechanical free wheel connection conformed as a friction clutch, comprising a first friction surface carried by one of the pinion/driver elements and a second friction surface fixed to the other one of the driver/pinion elements, - and an elastic device for initiating the self-locking of the free-wheel. Prior art With reference to figures 1 and 2, a starter 10 according to the prior art comprises an electric motor 11 provided with a casing 15, a stator 12 and a rotor 13 mounted coaxially, the stator 12 surrounding the rotor 13, which is mounted on a rotary shaft 14. The stator 12 is housed inside the casing 15, which is secured to the support 15 of the starter intended to be fixed to a fixed part of the motor vehicle. The rotor 13 comprises a rotor winding connected to a collector 17 fixed to the shaft 14 of the electric motor 11. The starter 10 also comprises an electromagnetic contactor 18 extending parallel to the electric motor 11 whilst being located radially above it. The contactor 18 is equipped with an excitation coil B, a moving contact 27 carried by a control rod (not referenced) and electrical supply terminals 19, 20. The terminals 19, 20 are conformed so as each to form a fixed contact inside the insulating cover 21. One of the terminals 19 is intended to be connected to the positive terminal of the battery, the other 20 is connected by means of a cable 22 to the brush holder 17' associated with the collector 17, here of the frontal or radial type or in a variant of the axial type. In figure 2 an element closing the casing 15 carrying a rear bearing for the shaft 14 can be seen, as described in the document FR A 2 796 990. The contactor 18 also comprises a moving core 23, a fixed core 24, a coil support (not referenced) surrounding a guide sleeve (not referenced) for the moving core 23 and a chamber (not referenced) serving to house the coil B. This chamber is connected to the cover 21, here by crimping. The fixed core 24, by means of its central opening, serves as a guide for the control rod for the contact 27 subjected to the action of a cutoff spring (not referenced) acting between the cover 21 and the moving contact 27. In figure 2, for more clarity, the coil B and its support have been partly omitted, along with part of the fixed core 24 and of the guide sleeve. When the coil B is energised, the moving core 23 is drawn by magnetic attraction in the direction of the fixed core 24 in order to simultaneously cause the movement, via the control rod, of the moving contact 27 in the direction of the fixed contacts of the contactor 18 and the actuation of a control means 25 for the starter head 26 in order to control the movement thereof between a rear idle position (figure 1) and a front position meshing with a toothed starting ring 300 rotationally connected, possibly elastically, with the flywheel of the internal combustion engine of the motor vehicle. In figures 1 and 2 the control means 25 consists of a control lever 25. A return spring 42, bearing on the chamber and on a collar fixed to the moving core, is mounted around the moving core 23 in order to urge it towards the rear idle position. A spring 41, referred to as a teeth against teeth spring, is housed inside the core 23 and cooperates with the top end of the lever 25 connected to the moving core 23 by means of a rod 43 connected to a spindle 44. This spring 41 acts between the bottom of its housing belonging to the core 23 and an end shoulder belonging to the rod 43, the other end of which cooperates with the top end of the lever 25 via the spindle 44. When the moving contact 27 comes into engagement with the fixed contacts of the terminals 19, 20 of the contactor 18, the electric motor 11 is supplied electrically so that the shaft 14 turns and drives the output shaft 28, which is mounted in a front bearing 29 of the support 16. The front end of the shaft 14, opposite to the collector 17, is configured so as to form a sun pinion belonging to an epicyclic train constituting a geared step-down device 30, which is interposed between the output shaft 28 and the aligned shaft 14 of the electric motor 11. This train comprises a fixed ring toothed internally in order to come into engagement with the sun pinions (not referenced) of the step-down device 30. A bearing (not referenced) acts radially between the front end of the shaft 14 and the rear end of the shaft 28 provided with a blind hole for receiving the bearing. The control lever 25, here in the shape of a fork, is coupled by its top part to the moving core 23 via the rod 43 and the spring 41, and comprises in its intermediate part a pivot spindle 31 for its pivoting mounting in the starter. The bottom part of the lever 25, in the form of a fork, is mounted in an annular groove 133 in the driver 33 and comprises teeth or shoes profiled for action on the flanks of the groove in the driver. The spindle 31 comprises here two portions extending from opposite faces of the body of the lever 25, here made from plastics material, advantageously being moulded in one piece with the lever 25. These portions are mounted pivotally for example in a two-part bearing comprising a first part connected to the support 16 whilst advantageously being moulded with it and a second part formed opposite forming a shim between the actuator 18, or more precisely the chamber thereof, and the casing 15, as described in the document FR A 2 699 605 filed on 23.12.92. In a variant it is the shim that carries two axial wings with holes for mounting portions of the spindle 31, the lever being interposed between the two wings, one of which can be seen at 131 in figure 2. In a variant the fixed toothed ring of the step-down device comprises an extension conformed so as to fulfil a function of articulation of the lever 25. For example, the extension consists of two lugs projecting radially and conformed so as to receive the portions of the spindle 31. In a variant there is provided a fixed base plate interposed between the support 16 and the casing 15 as described in the document FR A 2 725 758. It is the base plate that then carries an articulation support for the spindle 31. The lever is therefore mounted for pivoting on a fixed articulation support 131 for the starter by means of a spindle fixed to one of the lever/fixed articulation support elements, knowing that the structures can be reversed. The starter head 26 is mounted so as to slide on the output shaft 28, and comprises a drive pinion 32, a driver 33 actuated by the fork of the pivoting control lever 25, and a free-wheel 34 interposed axially between the driver 33 and the pinion 32. The driver 33 is provided internally with helical flutes in engagement in a complementary manner with external helical teeth 36 carried by the output shaft 28. The starter head 26 is thus driven in a helical movement when it is moved by the lever 25 in the direction of an axially fixed stop 35 carried by the shaft 28 in order to come into position before meshing, by means of its pinion 32, in engagement with the toothed starting ring 300 of the internal combustion engine of the motor vehicle. The free-wheel starter head 26 is equipped with a friction clutch, here frustoconical, in order to couple the starting pinion 32 to the driver 33. Such a friction clutch is of the type described in the document FR-A-2 826 696 (WO 03/002870). It has two complementary concave and convex rigid surfaces, for example frustoconical, cooperating by friction and respectively secured to the pinion 32 and driver 33 for transmitting the starting torque. For more information reference should be made to this document FR-A-2 826 696, in particular to pages 13 and 14 thereof. The clutch is locked in an engaged position when the electric motor 11 of the starter drives the toothed starting ring of the internal combustion engine on starting up (driving phase) and is automatically released at the end of starting when the toothed ring drives the pinion 32 at a speed of rotation greater than that of the driver 33 (free-wheel phase). The pinion 32 and the driver 33 of the starter head 26 each have a central bore for the output shaft 28 to pass. With reference to figures 3 and 4, the pinion 32 of the starter head 26 is fixed to a piece for coupling the pinion 32 to the driver 33. This coupling piece is provided at its external periphery with a first concave friction surface 37, here frustoconical in shape. The friction surface 37 belongs to the internal periphery of a skirt on the coupling piece here fixed to the pinion 36. In a variant the lining 37 is attached. The driver 33 is equipped at its internal periphery with helical drive flutes in engagement with the complementary teeth 36 provided at the external periphery of the output shaft 28. The driver 33 is also equipped externally with a groove 133 for receiving the fork of the control lever 25, and at the front with a friction or rubbing lining 39, convex in shape, here frustoconical in shape. This lining 39 is based on thermosetting or thermoplastic plastics material, advantageously with fillers, in order to obtain the coefficient of friction required with low wear. The lining 39 is anchored in an annular housing in the driver 33 and has at its periphery a second convex friction surface 40 cooperating in a complementary and coaxial fashion with the first friction surface 37 in order to form a frustoconical friction clutch constituting a mechanical free-wheel connection, here disengageable, between the pinion 32 and the driver 33. In a variant the friction surfaces are conformed so as to form a hemispherical friction clutch. A cover (not referenced) is crimped to a projection on the coupling piece and acts with axial clearance between the lining 39 and the coupling piece. In a variant, as described in the aforementioned document, the coupling piece is fixed to the driver so that the surface 37 belongs to the driver and the surface 39 to the pinion. It should be noted that, when the moving core 23 is attracted against the fixed core 24 of the contactor 18, the clearance d1 between the fixed stop 35 and the pinion 32 in the front position of meshing with the toothed ring on the flywheel of the internal combustion engine may be either positive (figure 3) or negative (figure 4) according to the geometrical scattering on the parts of the starter. In these figures the fixed core 24 and the moving core 25 then in abutment on the fixed core 24 have been shown schematically. Nevertheless, in this position of end movement of the moving core 23, the driver 33 and therefore the starter head 26 can also move under the action of the inertia and reaction forces between the flutes 38 and the teeth 36. In figure 4, the pinion 32 is in abutment against the stop 35, and the negative clearance d1 is absorbed following a compression travel d2 of the teeth against teeth spring 41 cooperating with the top end of the control lever 25. The pivoting of the latter about the spindle 31 acts on the driver 33 so as to press the second friction surface 40 of the lining 39 against the first friction surface 37. The self-locking of the starter head 26 is thus initiated, and the drive torque is transmitted normally to the pinion 32. On the other hand, the presence of a positive clearance d1 on the pinion 32 with respect to the stop 35 without compression of the spring 41 (see figure 3) can cause an absence of contact between the two friction surfaces 37, 40, which here inhibits the self-locking of the starter head 26. The friction lining 37 then turns freely or with a slipping effect facing the first friction surface 37 on the coupling piece, and no torque can be transmitted between the driver 33 and the pinion 32. Starting the thermal engine is then impossible. In order to be sure of obtaining the self-locking effect on the starter head 26, it will in principle suffice to size the starter so that the clearance d1 in the phase of driving of the pinion 32 against the stop 35 is always negative. A first drawback of such a solution is that, according to the geometrical scattering on the parts of the starter, the actuation force exerted by the lever 25 on the driver 33 when the contactor 38 is energised would be very high, thereby causing an increase in the mechanical pressure of the lining 39 on the first friction surface 37. This high contact pressure in the friction clutch would cause premature wear on the friction clutch, with the formation in addition of a high residual drag torque that would risk degrading the free-wheel function of the starter head 26. A second drawback of this solution with negative clearance is the mechanical impact that the stop 35 has to take each time the pinion 32 impacts in the drive phase. In figure 1 an axially acting elastic washer can be mounted compressed axially inside the free-wheel. This washer is then interposed between a front radial shoulder on the friction lining, secured in this case to the driver, and the internal face of the aforementioned cover crimped on the coupling piece, so as to elastically urge the friction surfaces in mutual contact. The result is a predetermined axial force that applies the friction surfaces against each other. The elastic washer can also be replaced by a helical compression spring or belong to the cover. Such a washer, in general terms such an elastic device for initiating the self-locking of the free-wheel by friction, is described in the documents FR A 2 826 696 (WO 03/002870) and FR A 2 772 433 (US A 6 237 442). According to the geometrical scattering or the wear on the parts of the starter head, an imprecise positioning of the elastic washer or of the spring inside the free-wheel may cause a variation in the contact pressure of the friction surfaces, which may affect the self-initiation function of the friction clutch or the free-wheel function of the starter head. Object of the invention The object of the invention consists of producing a starter equipped with a friction-operated free-wheel starter head that remedies the aforementioned drawbacks and makes it possible to reliably initiate the self-locking of the starter head in the drive phase. Another object of the invention is to improve functioning of the starter head in free-wheel phase. Another object of the invention is to increase the service life of the starter. The starter according to the invention of the type in which the coupling piece is fixed to one of the pinion/driver elements is characterised in that the elastic device comprises at least one initiation spring integrated in the starter head between the coupling piece and the other one of the driver/pinion elements, referred to as the second element, so as to separate the two friction surfaces from each other in the idle position of the starter head, whilst creating a torque by friction in order to initiate the said self-locking of the free-wheel. The presence of the initiation spring generates an axial or radial action in order to obtain a drag torque by friction between the driver and the pinion, whilst the friction surfaces are separated at rest, the idle position of the friction clutch corresponding to the idle position of the starter head. This drag torque is sufficient to initiate the self-locking of the starter in the drive phase precisely, but remains relatively low so as to not significantly reduce the speed differential in the free-wheel phase and not to obliterate the action of the teeth against teeth spring. The initiation spring makes it possible, in free-wheel phase, to decrease the contact pressure between the friction surfaces and to detach the friction surfaces from each other because it is arranged in the starter head so as to separate the driver with respect to the pinion, which makes it possible to reduce the wear and to improve functioning in free-wheel phase. The initiation spring is a filter function since it also makes it possible to damp the vibrations and in particular impacts when the friction surfaces come into contact with each other. The phenomena of hammering of the friction surfaces are therefore reduced. The friction surfaces of the free-wheel are thus preserved in all phases so that the service life of the starter is increased. In addition, in the case where the friction clutch of the free-wheel is frustoconical in shape, it benefits from greater latitude for modifying the angle of the friction surfaces because the initiation spring is arranged in the starter head so as to separate the driver with respect to the pinion. It is therefore possible for example to increase or decrease the angle of the friction surfaces. When the friction clutch is hemispherical in shape there is also the benefit of a greater latitude for modifying the radius of curvature. The stiffness of the initiation spring can be determined with less precision because this spring has an action that tends to separate the driver with respect to the pinion and release the friction surfaces. Other characteristics can be used in isolation or in combination in order to precisely initiate the self-locking of the starter head and unlock the friction surfaces in the free-wheel phase: - a stop is fixed to the coupling piece, which comprises, on the side opposite to the stop, a bottom fixed to the pinion, and the initiation spring is arranged between the bottom of the coupling piece and the front face of the driver in order to exert an axial action tending to apply the driver against the stop; - the friction surface of the driver belongs to a friction lining fixed to the driver and the initiation spring is arranged between the bottom of the coupling piece and the front face of the driver in order to exert an axial action tending to apply the rear face of the friction lining against the stop; - the stop is advantageously formed by a radial rim; - the initiation spring can be a washer elastically deformable in the axial direction, such as a Belleville washer; - the spring is formed by a helical compression spring; - advantageously a shoulder is provided belonging to the bottom and/or to the second driver/pinion element not fixed to the coupling piece in order to position the initiation spring; - the initiation spring is arranged between the internal periphery of the coupling piece and the external periphery of the second element not fixed to the coupling piece in order to create a radial friction action between the driver and the pinion; - the initiation spring comprises a corrugated elastic blade arranged between the internal periphery of the coupling piece and the external periphery of the second element not fixed to the coupling piece in order to create a radial friction action between the driver and the pinion; - the corrugated elastic blade is fixed in a cylindrical extension extending the skirt that the coupling piece has. In one embodiment the coupling piece is fixed to the pinion and the initiation spring acts between the rear face of the bottom of the coupling piece and the front face of the driver or between the skirt of the coupling piece and the driver. In a variant the coupling piece is fixed to the driver and the initiation spring acts between the front face of the bottom of the coupling piece and the rear face of the pinion or between the skirt of the coupling piece and the pinion. Several initiation springs can be provided. These springs are mounted for example in series or act in a staged manner. Summary description of the drawings Other advantages and characteristics will emerge more clearly from the following description of embodiments of the invention given by way of non-limiting example and depicted in the accompanying drawings, in which: - figure 1 is a schematic view, in perspective and partially cut away at the starter head, of a known starter according to the prior art; - figure 2 shows a view in axial section of the starter in figure 1; - figures 3 and 4 show schematic views of a known starter head in the drive phase, respectively with a clearance against stop that is positive (no pressing of the friction cone in the clutch) and negative (pressing of the two friction surfaces of the clutch); - figures 5 to 7 depict views in axial section of three variant embodiments according to the invention, each making use of an initiation spring integrated in the starter head; - figure 8 is a view in vertical section along the line 8-8 in figure 7, showing the form of the radial-action spring between the driver and the bell. Detailed description of several embodiments With reference to figures 5 to 8 the same reference numbers will be used to designate parts identical or similar to those in figures 1 to 4. In figures 5 to 7, for reasons of simplicity, the control lever 25 and the contactor have not been depicted. In figure 5, the starter head 26 comprises a drive pinion 32, a driver 33 adapted to be actuated by the fork of the control lever 25 in figure 1, and a free-wheel 34 formed by a friction clutch, here frustoconical in shape or in a variant hemispherical in shape. The latter is provided with two friction surfaces 37, 40 annular in shape and complementary. These surfaces are concave and convex in shape. The first friction surface 37 is carried internally by the frustoconical-shaped skirt 48 of a coupling piece 45 in the shape of a bell directed towards the driver 33. The skirt 48 is delimited axially by a bottom 46 fixed to the pinion 32 and by a rear stop 47 fixed to the coupling piece 45 at the largest-diameter free end. The skirt 48 and the coupling piece 45 are parts of revolution. The bottom 46 extends radially between the skirt 48 and the pinion 32 and has a planar annular support surface 49 arranged opposite the front face 50 of the driver 33 and of the lining 39. The stop 47 is formed by an annular rim radially framing the lining 39. For more information reference should be made to the document WO 03/002870. Thus, in one embodiment, the bottom 46 is attached by welding, for example of the laser type, to the pinion 32 having for this purpose a tubular extension, not referenced. In a variant the bottom 46 can be fixed by crimping to the tubular extension as in figure 11 of the document WO 03/002870. By thus producing the pinion and the coupling piece separately it is possible, for each of these parts, to choose the material thereof according to the function to be performed. In a variant, the pinion 32 and the coupling piece 45 constitute one and the same piece made from one and the same material or dual material, for example a dual-material sintering as in figures 1 and 2 or in figure 3 of the document WO 03/002870. In a variant, the bottom 46 is inclined, as can also be seen in figure 3 of this document WO 03/002870. The stop 47 consists in one embodiment of a circlip, as in figure 8 of the document WO 03/002870. In this case the skirt 48 carries internally the friction surface 38 formed by the internal periphery of the skirt in figures 5 to 8 and has at its free end a housing, such as a groove, for mounting a circlip for cooperating with the driver and making captive the parts of the starter head, which can thus be manipulated and transported. In a variant, this circlip is replaced by a rim or radially oriented tongues obtained bending the free end of the skirt inwards. In a variant the stop consists of a cover crimped to the free end of the skirt having for this purpose a protuberance as in figures 1 and 2. In a variant the free end of the skirt has blind mortices, whilst the stop has radial tenons at its external periphery engaging in a complementary manner in the axially oriented mortices. Next the lateral edges of the mortices are crushed locally in contact with the tenons in abutment on the bottoms of the mortices. In a variant the stop is moulded in one piece with the skirt of the coupling piece. A stop is therefore fixed to the annular shaped coupling piece, which comprises a bottom on the side opposite to the stop. Everything that has just been said also applies to the embodiments in figures 6 and 7. The second friction surface 40, in figures 5 to 8, is situated on the lining 39 at the external periphery of the driver 33 and extends parallel to the first friction surface 37 but over a shorter axial distance. The friction surfaces 37, 40 are complementary. The lining 39 is fixed to the driver whilst for example being fixed by adhesive bonding in an annular housing thereof or in a variant fixed by the insert moulding technique to the driver, advantageously made from plastics material, so that the lining 40 is anchored in the driver. Naturally the size of the stop 47 is defined so that it can cooperate with the rear face of the lining 39 (see figures 5 to 7). In the driving phase, the locking of the friction-operated starter head 26 with free-wheel 34 is obtained by the combined action of the flutes on the driver 33, driven by the electric motor via the teeth on the output shaft, and of the friction cone after engagement of the two friction surfaces 37, 40. In the locked position of the clutch of the free-wheel 34 (driving phase), the electric motor 11 drives the pinion 32 and the toothed wheel for starting the internal combustion engine. The clutch is released in the free-wheel phase when the internal combustion engine drives the pinion 32 at a speed of rotation greater than that of the driver 33. The driver 33 has an annual groove 133 for receiving the fork-shaped bottom part of the lever 25 in figure 1. To permit the reliable functioning of the starter head 26, the invention proposes to initiate the internal self-locking of the free-wheel 34 in the driving phase and to separate the friction surfaces 37, 40 in free-wheel phase. The initiation of self-locking is provided by an elastic device 51 internal to the free-wheel 34, conformed as a friction clutch, and intended to generate a low-intensity drag force and to release the friction surfaces in free-wheel phase. The presence of this initiation device 51 generates a drag torque by friction between the driver 33 and the pinion 32, the said torque being sufficient to initiate the self-locking of the starter head 26 in the driving phase, but relatively low so as not to significantly reduce the speed differential in the freewheel phase. According to the invention, the initiation of the self-locking of the friction clutch is provided by an elastic device 51 integrated in the starter head, with the formation of a reaction between one of the driver 33/pinion 32 elements and the coupling piece 45 fixed to the other one of the pinion 32/driver 33 elements. The reaction is of the axial type in figure 5 and 6, and radial in figures 7 and 8. Preferably the axial action exerted by the initiation device 51 within the starter head is less than the axial action exerted by the teeth against teeth spring (see figure 2) at the driver 33. In figures 5 to 8 the coupling piece 45 is fixed to the pinion whilst being in a single piece or fixedly attached to it in the aforementioned manner so that the elastic device 51 is arranged axially between the rear face of the pinion 32 and the front face of the driver 33 in figures 5 and 6 and radially between the internal periphery of the coupling piece and the external periphery of the driver in figures 7 and 8. The elastic device 51 according to figure 5 comprises a spring R1 consisting by way of example of a washer elastically deformable in the axial direction, such as a washer of the Belleville type. The spring R1 is interposed between the rear support surface 49 of the bottom 46 of the coupling piece 45, and the front face 50 of the driver 33, so as to separate the friction surfaces 37, 40 from each other, unlike the device in the documents FR-A-2772433 and WO 03/002870, where the self-initiation takes place by contact of the two complementary concave and convex shaped friction surfaces. In this figure 5 the spring 51 bears at its external periphery on the front face of the lining 39 belonging to the front face 50 of the driver, whilst at its internal periphery it bears on the surface 49 of the bottom 46. The rear face of the lining 39 of the friction clutch is held against the stop 47 on the skirt 48, in order to generate a residual torque by friction between the coupling piece 45 and the driver 33. The presence of the initiation spring R1 generates a drag torque by friction between the driver 33 and the pinion 32, the said torque being sufficient to initiate the self-locking of the starter head 26 in the drive phase but relatively low so as not to significantly reduce the speed differential in free-wheel phase. This free-wheel phase takes place according to a first step during which the friction surfaces are in contact with a reduction in the contact pressure and a second step during which the friction surfaces are detached with respect to each other under the action of the initiation spring. In the variant in figure 6, the spring R1 is replaced by a helical compression spring R2 fixed between the front face 50 of the driver 33 and a shoulder on the bottom 46. The effect of this spring R2 is identical to that of figure 5 and the result is a force pressing the lining 39 against the stop 47 on the skirt 48 after separation of the two friction surfaces 37, 40. With references to figures 7 and 8, the elastic device 51 comprises a radial-action spring R3, formed by an annular corrugated elastic blade. The blade is interposed between a cylindrical extension 52 of the skirt 48, and the peripheral surface of the lining 43. The friction surfaces 37, 40 remain separated in the idle position and the permanent friction effect of the spring R3 against the coupling piece 45 and the lining 39 allows the self-initiation of the clutch following the formation of torque between the pinion 32 and the driver 33. This force depends on the application and is chosen so as not to excessively interfere with the movement of the driver with respect to the pinion. In this embodiment the frustoconical-shaped skirt 48 is extended at its free end by an annular portion roughly in the shape of a U, the axially oriented annual bottom of which consists of the cylindrical extension 52 forming a strut between two radially oriented arms directed towards the axis of the starter head merged with the axis of the output shaft in figure 1. One of its arms is a portion connecting the strut 52 to the skirt 48, whilst the other arm, which is longer, constitutes the stop 47 adapted to cooperate with the rear face of the lining 39. The aforementioned U-shaped portion constitutes a housing in the form of a groove for the corrugated spring R3. The lining 39, annular in shape, has at its external periphery a first portion constituting the friction surface 40. This portion is extended by a second cylindrically-shaped portion 140, that is to say a second axially oriented annular portion. This portion 140 is a support portion for the corrugations for the spring R3, as can be seen in figure 8. This spring R3 therefore acts between the internal periphery of the strut 56 belonging to the internal periphery of the coupling piece and the portion 140 belonging to the external periphery of the driver 33. In all cases the resulting force at the starter head, or more precisely at the groove 133, produced by the elastic device according to the invention, is in all embodiments less than that the teeth against teeth spring in figure 2 would produce. Naturally, in the light of figures 7 and 8, the spring R1 in figure 5 can be replaced by an axially corrugated washer. In a variant it is an elastomer washer. The solutions with washers R1 are more compact axially than those in figure 6. The spring R2 in figure 6 makes it possible to obtain a longer elastic travel and in a variant has a variable pitch in order to obtain better progressiveness. In figure 6 the driver 33 can also be provided with a shoulder for centring the spring R2. Likewise in figure 5 the bottom 46 is in a variant provided with a centring shoulder for the internal periphery of the washer R2. The structures in figure 7 can be reversed so that the groove is formed in the lining 39, the support portion 140 constituting the bottom of the groove. In this case the strut is directly connected to the free end of the skirt. The spring R3 in a variant consists of a ring, for example in contact with the extension 52 connected to the skirt 48, whilst the stop is attached to the strut in order to be able to mount the ring of the spring R3. This ring of the spring R3 has at its internal periphery lugs distributed circumferentially for contact with the portion 140. The free end of the lugs is advantageously rounded. The lugs are advantageously inclined. The ring of the spring R3 is in one embodiment fixed, for example by adhesive bonding, to the extension 52 so that the presence of a groove is not necessary. The spring R3 bears in all cases on the extension 52 and on the portion 140. The initiation device 51 comprises in a variant several washers mounted in series, for example two Belleville washers with the mounting of a separation washer between the Belleville washers. In a variant the springs have a deferred staged action, a first spring acting first of all and then two springs. The parts of the starter head 26 can also be reversed. For example the skirt with the friction surfaces 37 is in a variant fixed to the driver 33, and the second convex friction surface 40 is in this case fixed to the pinion 32. For more information reference should be made to figures 5 and 6 of the aforementioned document WO 03/002870. The springs R1 and R2 in this case act between the front face of the bottom of the coupling piece constituting the front face of the driver and the rear face of the pinion arranged opposite the front face of the bottom of the coupling piece. In this case the spring R3 acts between the internal periphery of the coupling piece and the external periphery of the pinion. The portion 140 is then close to the pinion. In all embodiments the springs R1 and R2 act between the front face of the driver and the rear face of the pinion 32 arranged opposite the front face of the driver, whilst the spring R3 acts radially between the internal periphery of the skirt and the pinion/driver element that is not fixed to the skirt. The skirt with its inclined or radially oriented bottom can be in a single piece or be attached to the element with which is it integral. The invention also applies to a starter without a speed step-down device 30 between the electric motor 11 and the starter head 26. In this case the shaft 14 is also the output shaft. The collector 17 of the electric motor 11 can be either of the radial or axial type. The driver 33 and the pinion 32 can therefore be metal or made from sintered material. Here the driver 33 and the lever 25 are advantageously made from plastics material in order to obtain the required shape for these pieces easily by moulding. One of the flanks of the groove 133, the one that is closest to the free-wheel 34, can be covered with a metal part, for example by insert moulding. The other flank, furthest away from the free-wheel 34, is advantageously metal whilst being fixedly attached to the driver, for example by insert moulding. This flank consists for example of a metal washer. In this case a metal to plastics material contact is always obtained. The contactor 18 is in a variant separate and extends for example perpendicular to the shaft 14 of the motor 11 in the vicinity of the rear bearing of this shaft 14, as described in the document FR A 2 843 427. In this case the rod for connection to the moving core, which acts on the top part of the lever 25, is connected to this moving core by a second rod acting on the teeth against teeth spring and a return mechanism acting between the two rods. The rod 43 therefore acts directly or indirectly on the teeth against teeth spring. The pinion 32 is in a variant of the type emerging with respect to the support 16, as described in the document FR A 2 745 855. The lever 25 carries a spindle 31 for its pivotal mounting on a fixed articulation support 131 of the starter 25 (figure 2). In a variant it is the fixed articulation support that carries the spindle, the lever having a hole in it for the spindle to pass. In a variant the contactor is mounted coaxially with respect to the electric motor so that the starter head fulfils the role of moving core as described in the document FR A 2 841 941, to which reference should be made. The control means for moving the starter head is therefore not necessarily a lever. In a variant at least one covering is provided for the support 49, 50, 52, 140 of the initiation spring. For example, the front face 50 of the driver 33, advantageously made from plastics material, is formed by a metal washer fixed to the driver. The same can apply with regard to the rear face 49 of the coupling piece. The support portion 140 is in a variant metal. In a variant the covering is a noise-suppressant material. The friction surface 40 can be formed directly at the external periphery of the driver, whilst the friction surface 37 can belong to a friction lining fixed to the internal periphery of the skirt of the coupling piece. The skirt 48 can therefore be cylindrical in shape. In the description the starter is a starter for an internal combustion engine, also referred to as a thermal engine, for a motor vehicle, such as a light vehicle or a heavy goods vehicle, or a boat. The invention naturally applies to the case where the internal combustion engine is fixed and serves for example to drive at least one power take-off. Thus the internal combustion engine can be fixed and drive, advantageously via a clutch, a movement transmission shaft. All combinations are possible. CLAIMS 1. Starter for an internal combustion engine, in particular for a motor vehicle, provided with a flywheel with a toothed ring (300), comprising an output shaft (28) provided with teeth (36), a starter head (26), a pinion (32) belonging to the starter head (26), an electric motor (11) mechanically coupled to the starter head (26) mounted for axial sliding on the output shaft (28) between a rear idle position and a front position of meshing of the pinion (32) with the toothed ring on the flywheel of the internal combustion engine, the said starter head (26) comprising: - a driver (33) controlled by a means of control between the rear and front positions and equipped with drive flutes (38) in engagement with the complementary teeth (36) of the output shaft (28), - a piece coupling the pinion (32) to the driver (33) by means of a mechanical free-wheel (34) connection conformed as a friction clutch, comprising a first friction surface (37) carried by one of the pinion (32)/driver (33) elements and a second friction surface (40) fixed to the other one of the driver (33)/pinion (32) elements, - and an elastic device (51) for initiating the self-locking of the free-wheel (34), - the said coupling piece being fixed to one of the pinion (32)/driver (33) elements, referred to as the first element, - characterised in that the elastic device (51) comprises at least one initiation spring (R1, R2, R3) integrated in the starter head (26) between the coupling piece and the other one of the driver (33) - pinion (32) elements, referred to as the second element, which is not fixed to the coupling piece (45), so as to separate the two friction surfaces (37, 40) from each other in the idle position of the starter, whilst creating a torque by friction in order to initiate the said self-locking of the free-wheel (34). 2. Starter according to claim 1, characterised in that it comprises a stop (47) secured to the coupling piece (45), in that the coupling piece (45) comprises, on the side opposite to the stop (47), a bottom (46) secured to the pinion (32), whilst the driver (33) has a front face (50) opposite the bottom (46) of the coupling piece (45), and in that the initiation spring (R1, R2) is arranged between the bottom (46) of the coupling piece (45) and the front face (50) of the driver (33) in order to exert an axial action tending to apply the driver (33) against the stop (47). 3. Starter according to claim 1, characterised in that it comprises a stop (47) secured to the coupling piece (45), in that the coupling piece (45) comprises, on the side opposite to the stop (47), a bottom (46) secured to the driver (33), whilst the pinion (32) has a rear face opposite the bottom (46) of the driver (33), and in that the initiation spring (R1, R2) is arranged between the bottom (46) of the coupling piece (45) and the rear face of the pinion (32) in order to exert an axial action tending to apply the pinion (32) against the stop (47). 4. Starter according to claim 1, characterised in that it comprises a stop (47) secured to the coupling piece (45), in that the initiation spring (R1, R2) is arranged so as to exert an axial action tending to apply one of the pinion (32) - driver (33) elements against the stop (47) and in that the stop (47) is formed by a radial rim secured to the coupling piece (45). 5. Starter according to claim 1, characterised in that the initiation spring (R1) comprises a washer elastically deformable in the axial direction. 6. Starter according to claim 5, characterised in that the initiation spring is a Belleville washer. 7. Starter according to claim 1, characterised in that the initiation spring (R2) is formed by a helical compression spring. 8. Starter according to claim 4, characterised in that the bottom of the coupling piece (45) and/or the second driver (33) - pinion (32) element not secured to the coupling piece (45) has a shoulder for positioning the initiation spring (R1, R2). 9. Starter according to claim 1, characterised in that the initiation spring (R3) is of the radial action type and is arranged between the internal periphery of the coupling piece (45) and the external periphery of the second driver (33) - pinion (32) element not secured to the coupling piece (45) in order to create a radial friction action between the driver (33) and the pinion (32). 10. Starter according to claim 9, characterised in that the initiation spring (R3) is a corrugated elastic blade. 11. Starter according to claim 9, characterised in that the coupling piece (45) has a bottom (46) secured to the first pinion (32) - driver (33) element and a skirt (48) connected to the bottom (46) and in that the initiation spring (R3) bears on a cylindrical extension (52) extending the skirt (48) and on a cylindrical portion (140) belonging to the second driver (33) - pinion (32) element. 12. Starter according to claim 11, characterised in that at least one of the extension (52) - cylindrical portion (140) elements constitutes the bottom of a groove. 13. Starter according to claim 11, characterised in that the friction clutch is frustoconical in form, in that the coupling piece (45) has a bottom (46) secured to the first pinion (32) - driver (33) element and a frustoconical-shaped skirt (48) connected to the bottom (46) and in that, on the side opposite to its bottom (46), the coupling piece (45) carries a stop (47). 14. Starter according to claim 13, characterised in that the second friction surface (40) belongs to a friction lining (39). 15. Starter according to claim 14, characterised in that the cylindrical portion (140) belongs to the friction lining (39).

Full Text

Starter, in particular for a motor vehicle, equipped with a friction-driven
free-wheel starter head
Technical field of the invention
The invention relates to a starter for an internal combustion engine, in particular for a motor vehicle, provided with a flywheel with a toothed starting ring, comprising an output shaft provided with teeth, a starter head, a pinion belonging to the starter head, an electric motor for rotationally driving the output shaft mechanically coupled to the starter head mounted for axial sliding on the output shaft between a rear idle position and a front position of meshing of the starter head pinion with the toothed starting ring on the flywheel of the internal combustion engine, the said starter head comprising:
- a driver controlled by a means of control between its rear and front positions
and equipped with drive flutes in engagement with the complementary teeth of
the output shaft,
- a piece coupling the pinion to the driver by means of a mechanical free
wheel connection conformed as a friction clutch, comprising a first friction
surface carried by one of the pinion/driver elements and a second friction
surface fixed to the other one of the driver/pinion elements,
- and an elastic device for initiating the self-locking of the free-wheel.
Prior art
With reference to figures 1 and 2, a starter 10 according to the prior art comprises an electric motor 11 provided with a casing 15, a stator 12 and a rotor 13 mounted coaxially, the stator 12 surrounding the rotor 13, which is mounted on a rotary shaft 14. The stator 12 is housed inside the casing 15,

which is secured to the support 15 of the starter intended to be fixed to a fixed part of the motor vehicle. The rotor 13 comprises a rotor winding connected to a collector 17 fixed to the shaft 14 of the electric motor 11.
The starter 10 also comprises an electromagnetic contactor 18 extending parallel to the electric motor 11 whilst being located radially above it. The contactor 18 is equipped with an excitation coil B, a moving contact 27 carried by a control rod (not referenced) and electrical supply terminals 19, 20. The terminals 19, 20 are conformed so as each to form a fixed contact inside the insulating cover 21. One of the terminals 19 is intended to be connected to the positive terminal of the battery, the other 20 is connected by means of a cable 22 to the brush holder 17' associated with the collector 17, here of the frontal or radial type or in a variant of the axial type.
In figure 2 an element closing the casing 15 carrying a rear bearing for the shaft 14 can be seen, as described in the document FR A 2 796 990.
The contactor 18 also comprises a moving core 23, a fixed core 24, a coil support (not referenced) surrounding a guide sleeve (not referenced) for the moving core 23 and a chamber (not referenced) serving to house the coil B. This chamber is connected to the cover 21, here by crimping. The fixed core 24, by means of its central opening, serves as a guide for the control rod for the contact 27 subjected to the action of a cutoff spring (not referenced) acting between the cover 21 and the moving contact 27.
In figure 2, for more clarity, the coil B and its support have been partly omitted, along with part of the fixed core 24 and of the guide sleeve.
When the coil B is energised, the moving core 23 is drawn by magnetic attraction in the direction of the fixed core 24 in order to simultaneously cause the movement, via the control rod, of the moving contact 27 in the direction of the fixed contacts of the contactor 18 and the actuation of a control means 25 for the starter head 26 in order to control the movement thereof between a rear idle position (figure 1) and a front position meshing with a toothed starting

ring 300 rotationally connected, possibly elastically, with the flywheel of the internal combustion engine of the motor vehicle.
In figures 1 and 2 the control means 25 consists of a control lever 25.
A return spring 42, bearing on the chamber and on a collar fixed to the moving core, is mounted around the moving core 23 in order to urge it towards the rear idle position. A spring 41, referred to as a teeth against teeth spring, is housed inside the core 23 and cooperates with the top end of the lever 25 connected to the moving core 23 by means of a rod 43 connected to a spindle 44. This spring 41 acts between the bottom of its housing belonging to the core 23 and an end shoulder belonging to the rod 43, the other end of which cooperates with the top end of the lever 25 via the spindle 44.
When the moving contact 27 comes into engagement with the fixed contacts of the terminals 19, 20 of the contactor 18, the electric motor 11 is supplied electrically so that the shaft 14 turns and drives the output shaft 28, which is mounted in a front bearing 29 of the support 16. The front end of the shaft 14, opposite to the collector 17, is configured so as to form a sun pinion belonging to an epicyclic train constituting a geared step-down device 30, which is interposed between the output shaft 28 and the aligned shaft 14 of the electric motor 11. This train comprises a fixed ring toothed internally in order to come into engagement with the sun pinions (not referenced) of the step-down device 30.
A bearing (not referenced) acts radially between the front end of the shaft 14 and the rear end of the shaft 28 provided with a blind hole for receiving the bearing.
The control lever 25, here in the shape of a fork, is coupled by its top part to the moving core 23 via the rod 43 and the spring 41, and comprises in its intermediate part a pivot spindle 31 for its pivoting mounting in the starter.

The bottom part of the lever 25, in the form of a fork, is mounted in an annular groove 133 in the driver 33 and comprises teeth or shoes profiled for action on the flanks of the groove in the driver.
The spindle 31 comprises here two portions extending from opposite faces of the body of the lever 25, here made from plastics material, advantageously being moulded in one piece with the lever 25.
These portions are mounted pivotally for example in a two-part bearing comprising a first part connected to the support 16 whilst advantageously being moulded with it and a second part formed opposite forming a shim between the actuator 18, or more precisely the chamber thereof, and the casing 15, as described in the document FR A 2 699 605 filed on 23.12.92.
In a variant it is the shim that carries two axial wings with holes for mounting portions of the spindle 31, the lever being interposed between the two wings, one of which can be seen at 131 in figure 2.
In a variant the fixed toothed ring of the step-down device comprises an extension conformed so as to fulfil a function of articulation of the lever 25. For example, the extension consists of two lugs projecting radially and conformed so as to receive the portions of the spindle 31. In a variant there is provided a fixed base plate interposed between the support 16 and the casing 15 as described in the document FR A 2 725 758. It is the base plate that then carries an articulation support for the spindle 31.
The lever is therefore mounted for pivoting on a fixed articulation support 131 for the starter by means of a spindle fixed to one of the lever/fixed articulation support elements, knowing that the structures can be reversed.
The starter head 26 is mounted so as to slide on the output shaft 28, and comprises a drive pinion 32, a driver 33 actuated by the fork of the pivoting control lever 25, and a free-wheel 34 interposed axially between the driver 33 and the pinion 32. The driver 33 is provided internally with helical flutes in

engagement in a complementary manner with external helical teeth 36 carried by the output shaft 28. The starter head 26 is thus driven in a helical movement when it is moved by the lever 25 in the direction of an axially fixed stop 35 carried by the shaft 28 in order to come into position before meshing, by means of its pinion 32, in engagement with the toothed starting ring 300 of the internal combustion engine of the motor vehicle.
The free-wheel starter head 26 is equipped with a friction clutch, here frustoconical, in order to couple the starting pinion 32 to the driver 33. Such a friction clutch is of the type described in the document FR-A-2 826 696 (WO 03/002870). It has two complementary concave and convex rigid surfaces, for example frustoconical, cooperating by friction and respectively secured to the pinion 32 and driver 33 for transmitting the starting torque.
For more information reference should be made to this document FR-A-2 826 696, in particular to pages 13 and 14 thereof.
The clutch is locked in an engaged position when the electric motor 11 of the starter drives the toothed starting ring of the internal combustion engine on starting up (driving phase) and is automatically released at the end of starting when the toothed ring drives the pinion 32 at a speed of rotation greater than that of the driver 33 (free-wheel phase). The pinion 32 and the driver 33 of the starter head 26 each have a central bore for the output shaft 28 to pass.
With reference to figures 3 and 4, the pinion 32 of the starter head 26 is fixed to a piece for coupling the pinion 32 to the driver 33. This coupling piece is provided at its external periphery with a first concave friction surface 37, here frustoconical in shape.
The friction surface 37 belongs to the internal periphery of a skirt on the coupling piece here fixed to the pinion 36. In a variant the lining 37 is attached.

The driver 33 is equipped at its internal periphery with helical drive flutes in engagement with the complementary teeth 36 provided at the external periphery of the output shaft 28. The driver 33 is also equipped externally with a groove 133 for receiving the fork of the control lever 25, and at the front with a friction or rubbing lining 39, convex in shape, here frustoconical in shape. This lining 39 is based on thermosetting or thermoplastic plastics material, advantageously with fillers, in order to obtain the coefficient of friction required with low wear. The lining 39 is anchored in an annular housing in the driver 33 and has at its periphery a second convex friction surface 40 cooperating in a complementary and coaxial fashion with the first friction surface 37 in order to form a frustoconical friction clutch constituting a mechanical free-wheel connection, here disengageable, between the pinion 32 and the driver 33. In a variant the friction surfaces are conformed so as to form a hemispherical friction clutch.
A cover (not referenced) is crimped to a projection on the coupling piece and acts with axial clearance between the lining 39 and the coupling piece.
In a variant, as described in the aforementioned document, the coupling piece is fixed to the driver so that the surface 37 belongs to the driver and the surface 39 to the pinion.
It should be noted that, when the moving core 23 is attracted against the fixed core 24 of the contactor 18, the clearance d1 between the fixed stop 35 and the pinion 32 in the front position of meshing with the toothed ring on the flywheel of the internal combustion engine may be either positive (figure 3) or negative (figure 4) according to the geometrical scattering on the parts of the starter. In these figures the fixed core 24 and the moving core 25 then in abutment on the fixed core 24 have been shown schematically. Nevertheless, in this position of end movement of the moving core 23, the driver 33 and therefore the starter head 26 can also move under the action of the inertia and reaction forces between the flutes 38 and the teeth 36.

In figure 4, the pinion 32 is in abutment against the stop 35, and the negative clearance d1 is absorbed following a compression travel d2 of the teeth against teeth spring 41 cooperating with the top end of the control lever 25. The pivoting of the latter about the spindle 31 acts on the driver 33 so as to press the second friction surface 40 of the lining 39 against the first friction surface 37. The self-locking of the starter head 26 is thus initiated, and the drive torque is transmitted normally to the pinion 32.
On the other hand, the presence of a positive clearance d1 on the pinion 32 with respect to the stop 35 without compression of the spring 41 (see figure 3) can cause an absence of contact between the two friction surfaces 37, 40, which here inhibits the self-locking of the starter head 26. The friction lining 37 then turns freely or with a slipping effect facing the first friction surface 37 on the coupling piece, and no torque can be transmitted between the driver 33 and the pinion 32. Starting the thermal engine is then impossible.
In order to be sure of obtaining the self-locking effect on the starter head 26, it will in principle suffice to size the starter so that the clearance d1 in the phase of driving of the pinion 32 against the stop 35 is always negative. A first drawback of such a solution is that, according to the geometrical scattering on the parts of the starter, the actuation force exerted by the lever 25 on the driver 33 when the contactor 38 is energised would be very high, thereby causing an increase in the mechanical pressure of the lining 39 on the first friction surface 37. This high contact pressure in the friction clutch would cause premature wear on the friction clutch, with the formation in addition of a high residual drag torque that would risk degrading the free-wheel function of the starter head 26. A second drawback of this solution with negative clearance is the mechanical impact that the stop 35 has to take each time the pinion 32 impacts in the drive phase.
In figure 1 an axially acting elastic washer can be mounted compressed axially inside the free-wheel. This washer is then interposed between a front radial shoulder on the friction lining, secured in this case to the driver, and the internal face of the aforementioned cover crimped on the coupling piece, so

as to elastically urge the friction surfaces in mutual contact. The result is a predetermined axial force that applies the friction surfaces against each other. The elastic washer can also be replaced by a helical compression spring or belong to the cover.
Such a washer, in general terms such an elastic device for initiating the self-locking of the free-wheel by friction, is described in the documents FR A 2 826 696 (WO 03/002870) and FR A 2 772 433 (US A 6 237 442).
According to the geometrical scattering or the wear on the parts of the starter head, an imprecise positioning of the elastic washer or of the spring inside the free-wheel may cause a variation in the contact pressure of the friction surfaces, which may affect the self-initiation function of the friction clutch or the free-wheel function of the starter head.
Object of the invention
The object of the invention consists of producing a starter equipped with a friction-operated free-wheel starter head that remedies the aforementioned drawbacks and makes it possible to reliably initiate the self-locking of the starter head in the drive phase.
Another object of the invention is to improve functioning of the starter head in free-wheel phase.
Another object of the invention is to increase the service life of the starter.
The starter according to the invention of the type in which the coupling piece is fixed to one of the pinion/driver elements is characterised in that the elastic device comprises at least one initiation spring integrated in the starter head between the coupling piece and the other one of the driver/pinion elements, referred to as the second element, so as to separate the two friction surfaces from each other in the idle position of the starter head, whilst creating a torque by friction in order to initiate the said self-locking of the free-wheel.

The presence of the initiation spring generates an axial or radial action in order to obtain a drag torque by friction between the driver and the pinion, whilst the friction surfaces are separated at rest, the idle position of the friction clutch corresponding to the idle position of the starter head. This drag torque is sufficient to initiate the self-locking of the starter in the drive phase precisely, but remains relatively low so as to not significantly reduce the speed differential in the free-wheel phase and not to obliterate the action of the teeth against teeth spring.
The initiation spring makes it possible, in free-wheel phase, to decrease the contact pressure between the friction surfaces and to detach the friction surfaces from each other because it is arranged in the starter head so as to separate the driver with respect to the pinion, which makes it possible to reduce the wear and to improve functioning in free-wheel phase.
The initiation spring is a filter function since it also makes it possible to damp the vibrations and in particular impacts when the friction surfaces come into contact with each other. The phenomena of hammering of the friction surfaces are therefore reduced.
The friction surfaces of the free-wheel are thus preserved in all phases so that the service life of the starter is increased.
In addition, in the case where the friction clutch of the free-wheel is frustoconical in shape, it benefits from greater latitude for modifying the angle of the friction surfaces because the initiation spring is arranged in the starter head so as to separate the driver with respect to the pinion.
It is therefore possible for example to increase or decrease the angle of the friction surfaces.
When the friction clutch is hemispherical in shape there is also the benefit of a greater latitude for modifying the radius of curvature.

The stiffness of the initiation spring can be determined with less precision because this spring has an action that tends to separate the driver with respect to the pinion and release the friction surfaces.
Other characteristics can be used in isolation or in combination in order to precisely initiate the self-locking of the starter head and unlock the friction surfaces in the free-wheel phase:
- a stop is fixed to the coupling piece, which comprises, on the side opposite
to the stop, a bottom fixed to the pinion, and the initiation spring is arranged
between the bottom of the coupling piece and the front face of the driver in
order to exert an axial action tending to apply the driver against the stop;
- the friction surface of the driver belongs to a friction lining fixed to the driver
and the initiation spring is arranged between the bottom of the coupling piece
and the front face of the driver in order to exert an axial action tending to
apply the rear face of the friction lining against the stop;
- the stop is advantageously formed by a radial rim;
- the initiation spring can be a washer elastically deformable in the axial
direction, such as a Belleville washer;
- the spring is formed by a helical compression spring;
- advantageously a shoulder is provided belonging to the bottom and/or to the
second driver/pinion element not fixed to the coupling piece in order to
position the initiation spring;
- the initiation spring is arranged between the internal periphery of the
coupling piece and the external periphery of the second element not fixed to
the coupling piece in order to create a radial friction action between the driver
and the pinion;

- the initiation spring comprises a corrugated elastic blade arranged between
the internal periphery of the coupling piece and the external periphery of the
second element not fixed to the coupling piece in order to create a radial
friction action between the driver and the pinion;
- the corrugated elastic blade is fixed in a cylindrical extension extending the
skirt that the coupling piece has.
In one embodiment the coupling piece is fixed to the pinion and the initiation spring acts between the rear face of the bottom of the coupling piece and the front face of the driver or between the skirt of the coupling piece and the driver.
In a variant the coupling piece is fixed to the driver and the initiation spring acts between the front face of the bottom of the coupling piece and the rear face of the pinion or between the skirt of the coupling piece and the pinion.
Several initiation springs can be provided. These springs are mounted for example in series or act in a staged manner.
Summary description of the drawings
Other advantages and characteristics will emerge more clearly from the following description of embodiments of the invention given by way of non-limiting example and depicted in the accompanying drawings, in which:
- figure 1 is a schematic view, in perspective and partially cut away at the
starter head, of a known starter according to the prior art;
- figure 2 shows a view in axial section of the starter in figure 1;
- figures 3 and 4 show schematic views of a known starter head in the drive
phase, respectively with a clearance against stop that is positive (no pressing

of the friction cone in the clutch) and negative (pressing of the two friction surfaces of the clutch);
- figures 5 to 7 depict views in axial section of three variant embodiments
according to the invention, each making use of an initiation spring integrated
in the starter head;
- figure 8 is a view in vertical section along the line 8-8 in figure 7, showing
the form of the radial-action spring between the driver and the bell.
Detailed description of several embodiments
With reference to figures 5 to 8 the same reference numbers will be used to designate parts identical or similar to those in figures 1 to 4.
In figures 5 to 7, for reasons of simplicity, the control lever 25 and the contactor have not been depicted.
In figure 5, the starter head 26 comprises a drive pinion 32, a driver 33 adapted to be actuated by the fork of the control lever 25 in figure 1, and a free-wheel 34 formed by a friction clutch, here frustoconical in shape or in a variant hemispherical in shape. The latter is provided with two friction surfaces 37, 40 annular in shape and complementary. These surfaces are concave and convex in shape.
The first friction surface 37 is carried internally by the frustoconical-shaped skirt 48 of a coupling piece 45 in the shape of a bell directed towards the driver 33. The skirt 48 is delimited axially by a bottom 46 fixed to the pinion 32 and by a rear stop 47 fixed to the coupling piece 45 at the largest-diameter free end. The skirt 48 and the coupling piece 45 are parts of revolution.
The bottom 46 extends radially between the skirt 48 and the pinion 32 and has a planar annular support surface 49 arranged opposite the front face 50

of the driver 33 and of the lining 39. The stop 47 is formed by an annular rim radially framing the lining 39.
For more information reference should be made to the document WO 03/002870.
Thus, in one embodiment, the bottom 46 is attached by welding, for example of the laser type, to the pinion 32 having for this purpose a tubular extension, not referenced. In a variant the bottom 46 can be fixed by crimping to the tubular extension as in figure 11 of the document WO 03/002870.
By thus producing the pinion and the coupling piece separately it is possible, for each of these parts, to choose the material thereof according to the function to be performed. In a variant, the pinion 32 and the coupling piece 45 constitute one and the same piece made from one and the same material or dual material, for example a dual-material sintering as in figures 1 and 2 or in figure 3 of the document WO 03/002870.
In a variant, the bottom 46 is inclined, as can also be seen in figure 3 of this document WO 03/002870.
The stop 47 consists in one embodiment of a circlip, as in figure 8 of the document WO 03/002870.
In this case the skirt 48 carries internally the friction surface 38 formed by the internal periphery of the skirt in figures 5 to 8 and has at its free end a housing, such as a groove, for mounting a circlip for cooperating with the driver and making captive the parts of the starter head, which can thus be manipulated and transported.
In a variant, this circlip is replaced by a rim or radially oriented tongues obtained bending the free end of the skirt inwards.

In a variant the stop consists of a cover crimped to the free end of the skirt having for this purpose a protuberance as in figures 1 and 2.
In a variant the free end of the skirt has blind mortices, whilst the stop has radial tenons at its external periphery engaging in a complementary manner in the axially oriented mortices.
Next the lateral edges of the mortices are crushed locally in contact with the tenons in abutment on the bottoms of the mortices.
In a variant the stop is moulded in one piece with the skirt of the coupling piece.
A stop is therefore fixed to the annular shaped coupling piece, which comprises a bottom on the side opposite to the stop.
Everything that has just been said also applies to the embodiments in figures 6 and 7.
The second friction surface 40, in figures 5 to 8, is situated on the lining 39 at the external periphery of the driver 33 and extends parallel to the first friction surface 37 but over a shorter axial distance.
The friction surfaces 37, 40 are complementary.
The lining 39 is fixed to the driver whilst for example being fixed by adhesive bonding in an annular housing thereof or in a variant fixed by the insert moulding technique to the driver, advantageously made from plastics material, so that the lining 40 is anchored in the driver.
Naturally the size of the stop 47 is defined so that it can cooperate with the rear face of the lining 39 (see figures 5 to 7).

In the driving phase, the locking of the friction-operated starter head 26 with free-wheel 34 is obtained by the combined action of the flutes on the driver 33, driven by the electric motor via the teeth on the output shaft, and of the friction cone after engagement of the two friction surfaces 37, 40.
In the locked position of the clutch of the free-wheel 34 (driving phase), the electric motor 11 drives the pinion 32 and the toothed wheel for starting the internal combustion engine. The clutch is released in the free-wheel phase when the internal combustion engine drives the pinion 32 at a speed of rotation greater than that of the driver 33.
The driver 33 has an annual groove 133 for receiving the fork-shaped bottom part of the lever 25 in figure 1.
To permit the reliable functioning of the starter head 26, the invention proposes to initiate the internal self-locking of the free-wheel 34 in the driving phase and to separate the friction surfaces 37, 40 in free-wheel phase.
The initiation of self-locking is provided by an elastic device 51 internal to the free-wheel 34, conformed as a friction clutch, and intended to generate a low-intensity drag force and to release the friction surfaces in free-wheel phase.
The presence of this initiation device 51 generates a drag torque by friction between the driver 33 and the pinion 32, the said torque being sufficient to initiate the self-locking of the starter head 26 in the driving phase, but relatively low so as not to significantly reduce the speed differential in the freewheel phase.
According to the invention, the initiation of the self-locking of the friction clutch is provided by an elastic device 51 integrated in the starter head, with the formation of a reaction between one of the driver 33/pinion 32 elements and the coupling piece 45 fixed to the other one of the pinion 32/driver 33 elements.

The reaction is of the axial type in figure 5 and 6, and radial in figures 7 and 8.
Preferably the axial action exerted by the initiation device 51 within the starter head is less than the axial action exerted by the teeth against teeth spring (see figure 2) at the driver 33.
In figures 5 to 8 the coupling piece 45 is fixed to the pinion whilst being in a single piece or fixedly attached to it in the aforementioned manner so that the elastic device 51 is arranged axially between the rear face of the pinion 32 and the front face of the driver 33 in figures 5 and 6 and radially between the internal periphery of the coupling piece and the external periphery of the driver in figures 7 and 8.
The elastic device 51 according to figure 5 comprises a spring R1 consisting by way of example of a washer elastically deformable in the axial direction, such as a washer of the Belleville type. The spring R1 is interposed between the rear support surface 49 of the bottom 46 of the coupling piece 45, and the front face 50 of the driver 33, so as to separate the friction surfaces 37, 40 from each other, unlike the device in the documents FR-A-2772433 and WO 03/002870, where the self-initiation takes place by contact of the two complementary concave and convex shaped friction surfaces.
In this figure 5 the spring 51 bears at its external periphery on the front face of the lining 39 belonging to the front face 50 of the driver, whilst at its internal periphery it bears on the surface 49 of the bottom 46.
The rear face of the lining 39 of the friction clutch is held against the stop 47 on the skirt 48, in order to generate a residual torque by friction between the coupling piece 45 and the driver 33. The presence of the initiation spring R1 generates a drag torque by friction between the driver 33 and the pinion 32, the said torque being sufficient to initiate the self-locking of the starter head 26 in the drive phase but relatively low so as not to significantly reduce the speed differential in free-wheel phase.

This free-wheel phase takes place according to a first step during which the friction surfaces are in contact with a reduction in the contact pressure and a second step during which the friction surfaces are detached with respect to each other under the action of the initiation spring.
In the variant in figure 6, the spring R1 is replaced by a helical compression spring R2 fixed between the front face 50 of the driver 33 and a shoulder on the bottom 46. The effect of this spring R2 is identical to that of figure 5 and the result is a force pressing the lining 39 against the stop 47 on the skirt 48 after separation of the two friction surfaces 37, 40.
With references to figures 7 and 8, the elastic device 51 comprises a radial-action spring R3, formed by an annular corrugated elastic blade. The blade is interposed between a cylindrical extension 52 of the skirt 48, and the peripheral surface of the lining 43. The friction surfaces 37, 40 remain separated in the idle position and the permanent friction effect of the spring R3 against the coupling piece 45 and the lining 39 allows the self-initiation of the clutch following the formation of torque between the pinion 32 and the driver 33.
This force depends on the application and is chosen so as not to excessively interfere with the movement of the driver with respect to the pinion.
In this embodiment the frustoconical-shaped skirt 48 is extended at its free end by an annular portion roughly in the shape of a U, the axially oriented annual bottom of which consists of the cylindrical extension 52 forming a strut between two radially oriented arms directed towards the axis of the starter head merged with the axis of the output shaft in figure 1. One of its arms is a portion connecting the strut 52 to the skirt 48, whilst the other arm, which is longer, constitutes the stop 47 adapted to cooperate with the rear face of the lining 39.
The aforementioned U-shaped portion constitutes a housing in the form of a groove for the corrugated spring R3.

The lining 39, annular in shape, has at its external periphery a first portion constituting the friction surface 40. This portion is extended by a second cylindrically-shaped portion 140, that is to say a second axially oriented annular portion. This portion 140 is a support portion for the corrugations for the spring R3, as can be seen in figure 8. This spring R3 therefore acts between the internal periphery of the strut 56 belonging to the internal periphery of the coupling piece and the portion 140 belonging to the external periphery of the driver 33.
In all cases the resulting force at the starter head, or more precisely at the groove 133, produced by the elastic device according to the invention, is in all embodiments less than that the teeth against teeth spring in figure 2 would produce.
Naturally, in the light of figures 7 and 8, the spring R1 in figure 5 can be replaced by an axially corrugated washer. In a variant it is an elastomer washer. The solutions with washers R1 are more compact axially than those in figure 6.
The spring R2 in figure 6 makes it possible to obtain a longer elastic travel and in a variant has a variable pitch in order to obtain better progressiveness.
In figure 6 the driver 33 can also be provided with a shoulder for centring the spring R2. Likewise in figure 5 the bottom 46 is in a variant provided with a centring shoulder for the internal periphery of the washer R2.
The structures in figure 7 can be reversed so that the groove is formed in the lining 39, the support portion 140 constituting the bottom of the groove. In this case the strut is directly connected to the free end of the skirt.
The spring R3 in a variant consists of a ring, for example in contact with the extension 52 connected to the skirt 48, whilst the stop is attached to the strut in order to be able to mount the ring of the spring R3. This ring of the spring R3 has at its internal periphery lugs distributed circumferentially for contact

with the portion 140. The free end of the lugs is advantageously rounded. The lugs are advantageously inclined.
The ring of the spring R3 is in one embodiment fixed, for example by adhesive bonding, to the extension 52 so that the presence of a groove is not necessary.
The spring R3 bears in all cases on the extension 52 and on the portion 140.
The initiation device 51 comprises in a variant several washers mounted in series, for example two Belleville washers with the mounting of a separation washer between the Belleville washers. In a variant the springs have a deferred staged action, a first spring acting first of all and then two springs.
The parts of the starter head 26 can also be reversed. For example the skirt with the friction surfaces 37 is in a variant fixed to the driver 33, and the second convex friction surface 40 is in this case fixed to the pinion 32. For more information reference should be made to figures 5 and 6 of the aforementioned document WO 03/002870.
The springs R1 and R2 in this case act between the front face of the bottom of the coupling piece constituting the front face of the driver and the rear face of the pinion arranged opposite the front face of the bottom of the coupling piece.
In this case the spring R3 acts between the internal periphery of the coupling piece and the external periphery of the pinion. The portion 140 is then close to the pinion.
In all embodiments the springs R1 and R2 act between the front face of the driver and the rear face of the pinion 32 arranged opposite the front face of the driver, whilst the spring R3 acts radially between the internal periphery of the skirt and the pinion/driver element that is not fixed to the skirt.

The skirt with its inclined or radially oriented bottom can be in a single piece or be attached to the element with which is it integral.
The invention also applies to a starter without a speed step-down device 30 between the electric motor 11 and the starter head 26. In this case the shaft 14 is also the output shaft.
The collector 17 of the electric motor 11 can be either of the radial or axial type.
The driver 33 and the pinion 32 can therefore be metal or made from sintered material.
Here the driver 33 and the lever 25 are advantageously made from plastics material in order to obtain the required shape for these pieces easily by moulding.
One of the flanks of the groove 133, the one that is closest to the free-wheel 34, can be covered with a metal part, for example by insert moulding.
The other flank, furthest away from the free-wheel 34, is advantageously metal whilst being fixedly attached to the driver, for example by insert moulding. This flank consists for example of a metal washer.
In this case a metal to plastics material contact is always obtained.
The contactor 18 is in a variant separate and extends for example perpendicular to the shaft 14 of the motor 11 in the vicinity of the rear bearing of this shaft 14, as described in the document FR A 2 843 427. In this case the rod for connection to the moving core, which acts on the top part of the lever 25, is connected to this moving core by a second rod acting on the teeth against teeth spring and a return mechanism acting between the two rods. The rod 43 therefore acts directly or indirectly on the teeth against teeth spring.

The pinion 32 is in a variant of the type emerging with respect to the support 16, as described in the document FR A 2 745 855.
The lever 25 carries a spindle 31 for its pivotal mounting on a fixed articulation support 131 of the starter 25 (figure 2). In a variant it is the fixed articulation support that carries the spindle, the lever having a hole in it for the spindle to pass.
In a variant the contactor is mounted coaxially with respect to the electric motor so that the starter head fulfils the role of moving core as described in the document FR A 2 841 941, to which reference should be made. The control means for moving the starter head is therefore not necessarily a lever.
In a variant at least one covering is provided for the support 49, 50, 52, 140 of the initiation spring. For example, the front face 50 of the driver 33, advantageously made from plastics material, is formed by a metal washer fixed to the driver. The same can apply with regard to the rear face 49 of the coupling piece. The support portion 140 is in a variant metal. In a variant the covering is a noise-suppressant material.
The friction surface 40 can be formed directly at the external periphery of the driver, whilst the friction surface 37 can belong to a friction lining fixed to the internal periphery of the skirt of the coupling piece.
The skirt 48 can therefore be cylindrical in shape.
In the description the starter is a starter for an internal combustion engine, also referred to as a thermal engine, for a motor vehicle, such as a light vehicle or a heavy goods vehicle, or a boat.
The invention naturally applies to the case where the internal combustion engine is fixed and serves for example to drive at least one power take-off.

Thus the internal combustion engine can be fixed and drive, advantageously via a clutch, a movement transmission shaft.
All combinations are possible.

CLAIMS
1. Starter for an internal combustion engine, in particular for a motor vehicle, provided with a flywheel with a toothed ring (300), comprising an output shaft (28) provided with teeth (36), a starter head (26), a pinion (32) belonging to the starter head (26), an electric motor (11) mechanically coupled to the starter head (26) mounted for axial sliding on the output shaft (28) between a rear idle position and a front position of meshing of the pinion (32) with the toothed ring on the flywheel of the internal combustion engine, the said starter head (26) comprising:
- a driver (33) controlled by a means of control between the rear and front
positions and equipped with drive flutes (38) in engagement with the
complementary teeth (36) of the output shaft (28),
- a piece coupling the pinion (32) to the driver (33) by means of a mechanical
free-wheel (34) connection conformed as a friction clutch, comprising a first
friction surface (37) carried by one of the pinion (32)/driver (33) elements and
a second friction surface (40) fixed to the other one of the driver (33)/pinion
(32) elements,
- and an elastic device (51) for initiating the self-locking of the free-wheel (34),
- the said coupling piece being fixed to one of the pinion (32)/driver (33)
elements, referred to as the first element,
- characterised in that the elastic device (51) comprises at least one initiation
spring (R1, R2, R3) integrated in the starter head (26) between the coupling
piece and the other one of the driver (33) - pinion (32) elements, referred to as
the second element, which is not fixed to the coupling piece (45), so as to
separate the two friction surfaces (37, 40) from each other in the idle position
of the starter, whilst creating a torque by friction in order to initiate the said
self-locking of the free-wheel (34).

2. Starter according to claim 1, characterised in that it comprises a stop (47)
secured to the coupling piece (45), in that the coupling piece (45) comprises,
on the side opposite to the stop (47), a bottom (46) secured to the pinion (32),
whilst the driver (33) has a front face (50) opposite the bottom (46) of the
coupling piece (45), and in that the initiation spring (R1, R2) is arranged
between the bottom (46) of the coupling piece (45) and the front face (50) of
the driver (33) in order to exert an axial action tending to apply the driver (33)
against the stop (47).
3. Starter according to claim 1, characterised in that it comprises a stop (47)
secured to the coupling piece (45), in that the coupling piece (45) comprises,
on the side opposite to the stop (47), a bottom (46) secured to the driver (33),
whilst the pinion (32) has a rear face opposite the bottom (46) of the driver
(33), and in that the initiation spring (R1, R2) is arranged between the bottom
(46) of the coupling piece (45) and the rear face of the pinion (32) in order to
exert an axial action tending to apply the pinion (32) against the stop (47).
4. Starter according to claim 1, characterised in that it comprises a stop (47)
secured to the coupling piece (45), in that the initiation spring (R1, R2) is
arranged so as to exert an axial action tending to apply one of the pinion (32)
- driver (33) elements against the stop (47) and in that the stop (47) is formed
by a radial rim secured to the coupling piece (45).
5. Starter according to claim 1, characterised in that the initiation spring (R1)
comprises a washer elastically deformable in the axial direction.
6. Starter according to claim 5, characterised in that the initiation spring is a
Belleville washer.
7. Starter according to claim 1, characterised in that the initiation spring (R2)
is formed by a helical compression spring.
8. Starter according to claim 4, characterised in that the bottom of the
coupling piece (45) and/or the second driver (33) - pinion (32) element not

secured to the coupling piece (45) has a shoulder for positioning the initiation spring (R1, R2).
9. Starter according to claim 1, characterised in that the initiation spring (R3)
is of the radial action type and is arranged between the internal periphery of
the coupling piece (45) and the external periphery of the second driver (33) -
pinion (32) element not secured to the coupling piece (45) in order to create a
radial friction action between the driver (33) and the pinion (32).
10. Starter according to claim 9, characterised in that the initiation spring (R3)
is a corrugated elastic blade.
11. Starter according to claim 9, characterised in that the coupling piece (45)
has a bottom (46) secured to the first pinion (32) - driver (33) element and a
skirt (48) connected to the bottom (46) and in that the initiation spring (R3)
bears on a cylindrical extension (52) extending the skirt (48) and on a
cylindrical portion (140) belonging to the second driver (33) - pinion (32)
element.
12. Starter according to claim 11, characterised in that at least one of the
extension (52) - cylindrical portion (140) elements constitutes the bottom of a
groove.
13. Starter according to claim 11, characterised in that the friction clutch is
frustoconical in form, in that the coupling piece (45) has a bottom (46) secured
to the first pinion (32) - driver (33) element and a frustoconical-shaped skirt
(48) connected to the bottom (46) and in that, on the side opposite to its
bottom (46), the coupling piece (45) carries a stop (47).
14. Starter according to claim 13, characterised in that the second friction
surface (40) belongs to a friction lining (39).
15. Starter according to claim 14, characterised in that the cylindrical portion
(140) belongs to the friction lining (39).

Documents:

http://ipindiaonline.gov.in/patentsearch/GrantedSearch/viewdoc.aspx?id=foC97e62rSqF4rurfG+rPw==&loc=+mN2fYxnTC4l0fUd8W4CAA==

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Patent Number

279473

Indian Patent Application Number

6706/DELNP/2006

PG Journal Number

04/2017

Publication Date

27-Jan-2017

Grant Date

23-Jan-2017

Date of Filing

13-Nov-2006

Name of Patentee

VALEO EQUIPEMENTS ELECTRIQUES MOTEUR

Applicant Address

2 RUE, ANDRE-BOULLE, F-94017 CRETEIL CEDEX, FRANCE

Inventors:

#	Inventor's Name	Inventor's Address
1	BENOIT DUPEUX	1119, ROUTE DU LAC, F-38690 OYEUX, FRANCE
2	OLIVIER GIZOLME	CHEMIN DE LA TRAVERSE-LA POIZATIERE, F-69290 POLLIONNAY, FRANCE
3	CHRISTIAN MORNIEUX	7, RUE DE LA REPUBLIQUE, F-69600 OULLINS, FRANCE
4	ANDRE PIREYRE	7, RUE DOCTEUR GABRIEL FLORENCE, F-69740 GENAS, FRANCE
5	GILLES VADIN-MICHAUD	12 AVENUE SALVADOR ALLENDE, F-69100 VILLEURBANNE, FRANCE

PCT International Classification Number

F02N 15/06

PCT International Application Number

PCT/FR2005/001373

PCT International Filing date

2005-06-06

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	0406235	2004-06-09	France