Title of Invention

A STARTER FOR AN INTERNAL COMBUSTION ENGINE

Abstract

An inertia drive starter is proposed, in which no relay is required for the capability to engage in the toothed ring (47) of an internal combustion engine. In this starter, a forward movement of an output drive shaft (33) causes a pinion (45) to engage in the toothed rim (47) by means of a pole tube (9) which is provided on the stator (5) of the starter motor (5, 7) and carries out a pivoting movement about the motor axis when current flows through the starter motor (5, 7). In this case, means (55, 63, 77, 79) are provided which convert the pivoting movement of the pole tube (9) directly to an axial movement which acts on the output drive shaft (33) . (Figure 2)

Full Text

starter Prior Art The present invention relates to a starter for an internal combustion engine/ which has a starter motor, an input drive shaft which can be driven by the starter motor and an output drive shaft which is operatively connected to the input drive shaft, can be moved in the direction of its longitudinal axis and is provided with a pinion which can engage in a toothed rim on the internal combustion engine, with the output drive shaft being moved forward by means of an element in order to engage the pinion in the toothed rim, with this element being provided on the stator of the starter motor and carrying out a pivoting movement about the motor axis when current flows through the starter motor. So-called inertia drive starters are widely used as starters for internal combustion engines. These inertia drive starters have an electric starter motor, whose input drive shaft is operatively connected to an output drive shaft, which can be moved in the direction of its longitudinal axis. The input drive shaft is provided at the end remote from the starter motor with a I steep-pitched thread on which a driver shaft of the output drive shaft is arranged such that it can rotate and move linearly. This driver shaft of the output drive shaft is connected via a freewheeling mechanism to a shaft on which the pinion is located. Switching on > the starter motor causes the output drive shaft to move forward to engage with the driver shaft, the freewheeling mechanism and the pinion shaft, so that the pinion engages in a toothed wheel on the internal combustion engine. The mechanical engagement function is generally carried out by means of a mechanical relay which, in addition, generally also carries out the switching function for the starter motor. This combination of an engagement and switching function requires a starter relay to be fitted to the starter. Since the starter is located in the deformation area of a vehicle, there is a risk in the event of an accident of parts of the starter relay to which the battery voltage is applied touching the bodywork, which is at earth potential, and thus causing a short circuit. A starter which has already been disclosed is known, for exanple, from DE 196 25 057 CI. A starter which does not require a starter relay to be fitted to it and which carries out the engagement function of the starter is the subject of the prior German Application 100 16 706.3. This starter operates on the so-called braking inertia drive principle. In this case, the starter motor- has a pole tube which carries out a pivoting movement about the motor axis when current flows through the motor» This pivoting movement of the pole tube initiates a braking mechanism, which exerts a braking torque on the driver shaft of the output drive shaft. This braking torque results in the driver shaft being driven forwards via the steep-pitched thread by the input driver shaft of the motor, so that the pinion of the starter engages in the toothed rim on the internal combustion engine. According to the statements in the prior German Application, the braking apparatus comprises either a braking drum which is connected to the driver shaft and against which a braking wedge is pressed, or a catch which can be moved against a disc which is connected by a friction lock to the driver shaft, with a braking torque being exerted by the interlock between the catch and the disc on the driver shaft. The position change both of the braking wedge and of the catch requires a force in the radial direction with respect to the driver shaft, which is derived by means of a mechanism from the pivoting movement of the pole tube. Advantages of the Invention According to the features of Claim 1, means are provided which convert the pivoting movement of a stator element, which occurs when current flows through the starter motor, directly to an axial movement which acts on the output drive shaft. This invention means that there is no need for a starter relay to initiate a forward movement of the output drive shaft for the engagement process. Furthermore, the conversion of the pivoting movement of the starter element to an axial movement acting on the output drive shaft can be carried out by very simple technical means. Advantageous" embodiments and developments of the invention are described in the dependent claims. One advantageous embodiment for the conversion of the pivoting movement of the stator element to an axial movement of the output drive shaft may be to provide a guide track and a guide element which can slide along it, with the guide track or the guide element being operatively connected to the output drive shaft, which can move axially, and the guide element or the guide track being arranged on a part of the starter which does not move axially with the output drive shaft, The stator element is operatively connected to the guide track or to the guide element such that the guide element slides along the guide track during pivoting movement of the stator element. The guide track and the guide element are shaped such that the process of the guide element sliding along the guide track results in the output drive shaft carrying out an axial movement. Balls or roller bodies, by way of example, may be inserted between the guide track and the guide element, in order to reduce the friction. A disc which projects essentially radially is advantageously mounted on the output drive shaft such that it can rotate about the axis of the output drive shaft and is supported axially in the forward movement direction against a spring force. This spring force assists the engagement of the starter pinion in the toothed rim on the internal combustion engine. The starter element can be connected in an interlocking and or force-fitting manner to the disc such that, when the stator element pivots, a guide element which is provided on the disc slides along the guide track, which rises in the forward movement direction of the output drive shaft, with the disc carrying out an axial movement with the output drive shaft. The guide track or the guide element can be arranged on the stator element, for example. The stator element advantageously comprises a pole tube which is part of the stator and is mounted such that it can pivot about the motor axis, in which case a spring element may be provided to counteract the torque which acts on the pole tube and is produced when current flows through the motor. It is expedient for a spring element to be inserted between the disc and the housing of the starter, which exerts a spring force on the disc, and hence on the output drive shaft, in the opposite direction to the forward movement direction. This spring element assists the disengagement process of the starter. As in a conventional inertia drive starter, the output drive shaft is also expediently driven by the input drive shaft via a steep-pitched thread in the starter according to the invention. Drawing The invention will be explained in more detail in the following text with reference to a number of exemplary embodiments which are illustrated in the drawing, in which: Figure 1 shows a longitudinal section through a starter, Figures 2 to 4 show a three-dimensional illustration of a detail of the starter with the pole tube and output drive shaft in various positions, and Figure 5 shows a detail of a disc, which is arranged on the output, drive shaft, with an arm of the pole tube engaging in. it. Description of the Exemplary Embodiments The starter which is illustrated in the form of a longitudinal section in the figure has a two-part housing, with a housing part 1 surrounding a starter motor and a second housing part 3 holding the input drive bearing of the starter. The starter motor comprises, in a known manner, a stator 5 and a rotor 7 which is mounted in it such that it can rotate. The stator 5 has a pole tube 9 and stator poles 11 which are arranged in it and are in the form of permanent magnets. The pole tube 9 forms the magnetic feedback path for the stator poles 11, which are arranged concentrically around the rotor 7. The rotor 7 has a motor shaft 13, which is connected to a laminated core such that they rotate together. One or more rotor windings is or are incorporated in slots, which are not shown, in the laminated core. The motor shaft 13 which emerges from the starter motor is coupled to a gear system, preferably an epicyclic gear system 15. The motor shaft 13 in this case drives a sun wheel 17, and the sun wheel 17 engages with planet gears 19 and 21, which in turn roll in a hollow wheel 23. The hollow wheel is connected to an intermediate bearing. The planet gears 19 and 21 are held by a planet carrier 27. The intermediate bearing 25 is arranged in a fixed position and such that it cannot rotate in the housing 3 of the starter. The planet carrier 27 is connected to an input drive shaft 29 such that they rotate together, for example integrally. A driver shaft 31 of an output drive shaft 33 is fitted to the input drive shaft 29. The input drive shaft 29 and the driver shaft 31 are coupled to one another via a steep-pitched thread 35. This steep-pitched thread, which connects the input drive shaft 29 and the driver shaft 31 to one another, represents a so-called engagement gear system. The driver shaft 31 merges into an outer ring 37 of a freewheeling mechanism 39. The outer ring 37 of the freewheeling mechanism 39 drives an inner ring 41 via clamping bodies that are not illustrated, and the inner ring 41 is connected to a pinion shaft 43 of the output drive shaft 33. At its end which projects out of the housing 3 of the starter, the pinion shaft 43 is equipped with a pinion 45. When the motor shaft 13 rotates, the pinion shaft 43 is moved forwards by the engagement gear system, which is in the form of a steep-pitched thread 35, between the input drive shaft 29 and the output drive shaft 33, so that the pinion 45 engages in a toothed rim 47 on an internal combustion engine, which is not illustrated. The engagement process and the disengagement process will be described in more detail further below. In the exemplary embodiment illustrated in Figure 1, the input drive shaft 29 is mounted within the output drive shdft 33 by means of two bearings 49 and 51, which are arranged axially one behind the other, such that it can rotate. The output drive shaft 33 is furthermore mounted in the housing part 3, via a bearing 53, such that it can rotate about its longitudinal axis. The pole tube 9 of the starter motor is mounted such that it can pivot through a specific angle (approximately 10^ to 30°) about the motor axis (motor shaft 13). One or more - preferably three - arm or arms 55 is or are located on the pole tube 9 and extends or extend into the housing part 3 in which the gear system for driving the output drive shaft 33 is located. Each arm 55 of the pole tube 9 is passed through a cut-out 57 on the. outer circumference of the intermediate bearing 55 [sic], which is arranged such that it cannot rotate in the housing part 3. Each cut-out 57 on the intermediate bearing 25 has two stops 59 and 61, which limit the pivoting movement of the pole tube 9 about the motor axis, The perspective illustrations of a detail of the starter in Figures 2 to 4 show a cut-out 57 on the intermediate bearing 25, with its two stops 59 and 61, and an arm 55 of the pole tube 9 inserted into it. As soon as current is applied to the starter motor, the electromagnetic forces which are produced between the rotor and the stator result in a torque acting on the pole tube 9, so that the pole tube 9 is rotated in a specific direction, for example in the clockwise direction, about the motor axis, A spring element (which is not shown in the drawing) is provided, and counteracts this torque of the pole tube 9. The spring element may, for exarrple, be installed on the intermediate bearing 25. The magnitude of the torque which acts on the pole tube 9 depends on the magnitude of the current flowing through the rotor winding. ' A disc 63 which projects essentially radially is mounted on the driver shaft 31 of the output drive shaft 33, such that it can rotate about the axis of the driver shaft 31 of the output drive shaft 33. The disc 63 is secured against axial movement in the opposite direction to the foan/^ard movement direction of the output drive shaf t 33. This is achieved, for example, by means of a holding ring 65, which is placed on the driver shaft 31 and on which the disc 63 rests. The holding ring 65 is secured by means of a locking ring 67 against axial movement in the opposite direction to the forward movement direction of the output drive shaft 33. A supporting ring 69 is fitted to the driver shaft 31 on the side of the disc 63 which faces the freewheeling mechanism 39 and is pressed against the disc 63 by a spring 71 which is supported on the outer ring 37 of the freewheeling mechanism 39. As a result of its function during engagement of the pinion 45 in the toothed rim 47, this spring is referred to in the following text as the engagement spring 71, A further spring 73 is inserted between the disc 63 and the housing part 3 and, like the engagement spring 71, exerts a pressure on the disc 63, and hence on the output driver shaft 33, in the opposite direction to the forward movement direction of the output drive shaft 33. This second spring 73 is referred to in the following text as the disengagement spring, since it assists the process of disengagement of the pinion 45 from the toothed rim 47. The previously mentioned engagement and disengagement forces may also be applied by other spring elements which are arranged at other points in the starter than those shown in the figures. By way of example, the disengagement spring 73 could also be inserted between the pinion shaft 43 of the output drive shaft 33, which can move axially, and the pinion end of the axially fixed input drive shaft 29. The engagement process will now be described with reference to Figures 2 to 4, which illustrate different phases of the engagement process. For each arm 55 of the pole tube 9, the outer edge of the disc 63 has a cut-out 75, of such a size that the respective arm 55 of the pole tube 9 has no play in the radial direction, but in which the aira 55 can be moved in the axial direction. It is thus possible for the disc 63 also to rotate on the driver shaft 31 during pivoting movement of the pole tube 9, but the disc 63 cannot be moved in the axial direction relative to the pole tube 9\ The disc 63 has at least one axial bulge 77, pointing . in the direction of the pole tube 9. An axial projection 79, which faces the disc 63, is located on the stationary intermediate bearing 25, in the area of each bulge 77 on the disc 63 • The projection 79 is provided with a guide track 81, along which the bulge 77 on the disc 63 can slide, with the bulge 77 and the guide track 81 being shaped such that the disc 63 is moved forwards when its bulge 67 slides along the guide track 81. Figure 2 shows the starter in its rest position, when no current is flowing through the starter motor. At this stage, there is still no torque acting on the pole tube 9, and it rests against the left-hand stop 59 of the cut-out 57 in the intermediate bearing 25. In this rest position, the output drive shaft 33 is pushed back by the disc 63, which is arranged on it, in the direction of the starter motor to such an extent that the bulge on the disc 63 rests on the intermediate bearing 25. If current is now applied to the starter motor, the pole tube 9 is subject to a torque in the clockwise direction, when seen from the pinion end of the starter in the exemplary embodiment illustrated in Figures 2 to 4. As the motor current rises, the pole tube 9 with its arms 55 pivots in the direction of the second stop 61 of the cut-out 57, which is associated with each arm 55, in the intermediate bearing 25. As shown in Figure 3, the pivoting movement of each arm 55 of the pole tube 9 drives the disc 63, with the bulge 77 on the disc 63 sliding along the guide track 81 on the stationary projection 79 on the intermediate bearing 25 and in the process being moved forwards together with the output drive shaft 33 in the direction of the toothed rim 47 on the internal combustion engine. In this way, the output drive shaft 33 is first of all pushed forwards until the teeth of the pinion 45 of the starter meet the teeth in the toothed rim 47 of the internal combustion engine. The steep-pitched thread 35 between the input drive shaft 29 and the driver shaft 31 results in the output drive shaft 33 being driven further forwards with the toothed rim 45 against the spring force of the engagement spring 71, and being rotated until the teeth on the pinion 45 meet the gaps between the teeth in the toothed rim 47 of the internal combustion engine, with the output drive shaft being driven further forwards until the pinion 45 engages in the toothed rim 47. This completes the forward movement of the output drive shaft 33. Figure 3 shows the position of the pole tube 9 and of the disc 63 in this engaged position. Further pivoting movement of the pole tube 9 as far as the stop 61 on the cut-out 57 in the stationary intermediate bearing 25 results in the disc 63 being pushed forwards against the spring force of the engagement spring 71 so far that it is pushed over the end face of at least one step 83, which is integrally formed on the intermediate bearing 25 and extends in the axial direction. In this position, the disc 63 is locked to the output drive shaft 33. This position is shown in Figure 4. Once the engagement process as already described has been completed/ the internal combustion engine is caused to rotate by the pinion 45 of the output drive shaft 33/ which is driven by the starter motor, until the internal combustion engine is running on its own. The load on the starter motor then decreases, with the consequence that the motor current becomes less and, as a result of thiS/ the torque acting on the pole tube 9 is reduced. When the torque which is exerted on the pole tube 9 falls below a specific value, then the spring force of a pole tube resetting spring, which is not shown in the drawing, becomes the dominant factor, the disc 63 is unlocked and the disengagement spring 73 pushes the disc 63 together with the output drive shaft 33 in the direction of the starter motor. In the process, guided by the guide track 81 on the stationary projection 79, the disc 63 is rotated in the anticlockwise direction together with the pole tube 9 until the pole tube 9 is pivoted back with its arms 55 as far as the stop 59 on the respective cut-out 57 in the intermediate bearing 35. During this process, the pinion 45 once again disengages from the toothed rim 47 on the internal combustion engine. This disengagement process is also initiated when the current to the starter motor is switched off, for example by releasing the ignition key. One design variant provides for the disc 63 and the intermediate bearing 25 to be designed somewhat differently. While, in this case, the step 83 projects into an opening in the disc 63 and represents a radial stop for the opening of the disc 63, a further exemplary embodiment provides, on the one hand, for the opening (which is in the form of a slightly curved elongated hole) to be arranged between two bulges 77 in the disc 63. On the other hand, provision is made for the step 83 to be arranged in a corresponding manner to this on an axial end face of the projection 79 rather than in the area of the guide track 81. The single step 83 is now in the form of a pin which extends in the axial direction from the projection 79, This pin is in the form of a metallic pin and is pushed into the intermediate bearing 25. This pin has the advantage that it is highly resistant to wear and, instead of this, can also be extrusion coated with the intermediate bearing 25. Furthermore, the pin (which is preferably made of steel) can also be welded in place by means of an ultrasound welding process, or can also be screwed in. Since the metallic version of the step is more resistant to wear, the disc 63 may be designed to be thinner, which results in advantages of reduced weight and less inertia. In contrast to the exemplary embodiment illustrated in Figures 1 to 4/ the pivoting movement of the pole tube 9 can be converted to an axial movement of the output drive shaft 33 in many different ways. In principle, this conversion is carried out by means which comprise a guide track and a guide element which slides along it, with the guide track or the guide element being operatively connected to the output drive shaft, which can move axial ly, and the guide element or the guide track being arranged on a part of the starter which does not move axially with the output drive shaft. In this case, the pole tube 9 must be operatively connected to the guide track or to the guide element such that the guide element slides along the guide track when the pole tube 9 carries out a pivoting movement. The guide track and the guide element must be shaped such that the process of the guide element sliding along the guide track results in the output drive shaft 33 carrying out an axial movement. In the exemplary embodiment which is illustrated in Figure 5, which shows a detail of the pole tube 9 and of the disc 33 [sic] which is arranged on the output drive shaft 33, the guide track is formed by the arm 55 of the pole tube 9. To be precise, the area of the pole tube arm 55 which projects into the recess 75 in the disc 63 points in the direction of the side flanks 85 and 87 which fold towards the disc 63. These side flanks 85, 87 form guide tracks for the steps 89 and 91 which bound the recess 75. When the pole tube 9 is pivoted, either the step 89 slides along the side flank 85 or the step 91 slides along the side flank 87 of the pole tube 9, so that the disc 63 is moved forwards. In order to reduce the possibility of the steps 89 and 91, respectively, becoming jammed on the respective side flanks 85 and 87 of the pole tube 9, the steps 89 and 91 are rounded. In order to reduce the friction between the embodiments of the guide track and guide element as described above, balls or roller bodies can be inserted between the guide track and guide element. ROBERT BOSCH GMBH, 70442 Stuttgart Claims 1. Starter for an internal combustion engine, which has a starter motor (5, 7), an input drive shaft (29) which can be driven by the starter motor (5, 7) and an output drive shaft (33) which is operatively connected to the input drive shaft (29) , can be moved in the direction of its longitudinal axis and is provided with a pinion (45) which can engage in a toothed rim (47) on the internal combustion engine, with the output drive shaft (33) being moved forward by means of an element (9) in order to engage the pinion (45) in the toothed rim (47) , with this element (9) being provided on the stator (5) of the starter motor (5, 7) and carrying out a pivoting movement about the motor axis when current flows through the starter motor (5, 7) , characterized in that means (55, 63, 77, 79, 85, 87, 89, 91) are provided which convert the pivoting movement of the stator element (9) directly to an axial movement which acts on the output drive shaft (33). 2. Starter according to Claim 1, characterized in that the means comprise a guide track (81, 85, 87) and a guide element (77, 89, 91) which can slide along it, with the guide track (81, 85, 87) or the guide element (77, 89, 91) being operatively connected to the output drive shaft (33), which can move axially, and the guide element (77, 89, 91) or the guide track (81, 85, 87) being arranged on a part (25) of the starter which does not move axially with the output drive shaft (33) , in that the stator element (9) is operatively connected to the guide track (81, 85, 87) or to the guide element (77, 89, 91) such that the guide element (77, 89, 91) slides along the guide track (81, 85, 87) during pivoting movement of the stator element (9) , and in that the guide track (81, 85, 87) and the guide element (77, 89, 91) are shaped such that the process of the guide element (77, 89, 91) sliding along the guide track (81, 85, 87) results in the output drive shaft (33) carrying out an axial movement. 3. Starter according to one of Claims 1 or 2, characterized in that a disc (63) which projects signi ficantly radially is mounted on the output drive shaft (33) such that it can rotate about the axis of the output drive shaft (33) and is supported axially in the forward movement direction against a spring force (71) . 4. Starter according to one of Claims 2 or 3, characterized in that the stator element (9) is connected in an interlocking and/or force-transmitting manner to the disc (63) such that, when the stator element (9) pivots, a guide element (77) which is provided on the disc (63) slides along the guide track (81) , which rises in the forward movement direction of the output drive shaft (33), with the disc (63) carrying out an axial movement with the output drive shaft (33) . 5. Starter according to Claim 2, characterized in that the guide track (85, 87) or the guide element is arranged on the stator element (9). 6. Starter according to one of the preceding claims, characterized in that a pole tube (9) which is part of the stator (5) of the starter motor is mounted such that it can pivot about the motor axis, and in that a spring element is provided which counteracts the torque which acts on the pole tube (9) and is produced when current flows through the motor. 7. Starter according to Claim 3, characteri zed in that a spring element (73) is inserted between the disc (63) and "the housing (3) of the starter and exerts a spring force on the disc (63), and hence on the output drive shaft (33), in the opposite direction to the forward movement direction. 8. Starter according to one of the preceding claims, characterized in that the input drive shaft (29) drives the output drive shaft (33) via a steep-pitched thread (35) ,

Documents:

0411-chenp-2003 abstract-duplicate.pdf

0411-chenp-2003 claims-duplicate.pdf

0411-chenp-2003 description (complete)-duplicate.pdf

0411-chenp-2003 drawings-duplicate.pdf

411-chenp-2003-abstract.pdf

411-chenp-2003-claims.pdf

411-chenp-2003-correspondnece-others.pdf

411-chenp-2003-correspondnece-po.pdf

411-chenp-2003-description(complete).pdf

411-chenp-2003-drawings.pdf

411-chenp-2003-form 1.pdf

411-chenp-2003-form 18.pdf

411-chenp-2003-form 3.pdf

411-chenp-2003-pct.pdf