Title of Invention

AN ENGINE START CONTROL APPARATUS

Abstract

Engine strtability to be imporoved in a reverse rotation control in which a crank shaft (201) is rotated reverse up to a prepetermined position just after the stop of a engine so as to be ready for the next engine start. An engine start control apparatus including reverse rotation control means (75) which starts the supply of electric power for reverse rotation to a starter motor (1) just after the stop of an engine, crank angle detecting means (30,73) for detectting that a crank shaft, when rotating reverse, has reached an angle corresponding to a top dead centre of a piston, and reversing load detecting means (74) for detecting a reversing load on the crank shaaft, the reverse rotation control means terminaing the supply of electric power for reverse rotation in response to the arrival of the crank shaft at the angle corresponding to the top dead center detected by the crank angle detecting means ["X" mark on curved line A in Fig. 6 (c) or in reponse to a rise of the reversing load detected by the reversing rload detecting means ["X" mark on curved line B in Fig. 6 (c)], whichever is the earlier.

Full Text

FORM 2 THE PATENTS ACT 1970 [39 OF 1970] COMPLETE SPECIFICATION [See Section 10 ; rule 13]] "An engine start control apparatus" HONDA GIKEN KOGYO KABUSHIKI KAISHA, a corporation of Japan, 1-1, Minamiaoyama 2-chome, Minato-ku, Tokyo, Japan. The following specification particularly describes the nature of the invention and the manner in which it is to be performed:- DESCRIPTION ENGINE START CONTROL APPARATUS 5 Technical Field The present invention relates to an engine start control apparatus for starting an engine by cranking the engine with a starter motor. Particularly, the present invention is concernedwith an engine start control apparatus wherein, after 10 the stop of an engine, a crank shaft is cranked in a reverse direction up to a predetermined position to improve the startability. Background Art 15 A technique of rotating a crank shaft reverse up to a predetermined position before starting an engine and starting the engine at that reversed position, thereby decreasing a cranking torque at the time of starting the engine and improving the startability of the engine, is disclosed, for example, 2 0 in Japanese Published Unexamined Patent Application No. Hei 6-64451 or Hei 7-71350 . According to the prior art just referred to above, since the crank shaft is rotated reverse with a large cranking torque, the crank shaft is returned up to just before arrival at a 25 compression top dead center which the crank shaft has passed in its forward rotation. Therefore, when the supply of electric power for reverse rotation to a drive (starter) motor is stopped, the crank shaft advances in the forward direction due to a compressive reaction force of a piston. In the control method wherein the crank shaft is rotated 5 reverse at the time of starting an engine and is rotated forward immediately thereafter, as in the above prior art, the aforesaid compressive reaction force and a forward driving force developed by the starter motor are transmitted simultaneously to the crank shaft, so even if the crank shaft 10 advances in the forward direction under the aforesaid compressive reaction force, the startability of the engine is not impaired thereby. On the other hand, according to a system wherein the crank shaft is rotated reverse up to a predetermined position just 15 after the stop of an engine, not at the time of starting the engine, so as to be ready for the next engine start, if the crank shaft advances in the forward direction under a compressive reaction force of a piston, a desired inertia force is not obtained when the engine is to be started next because 20 an approach-run distance becomes shorter, thus giving rise to the problem that the engine startability cannot be improved to a satisfactory extent. It is an object of the present invention to solve the above conventional problem and attain a satisfactory 25 improvement of the engine startability in a reverse rotation control wherein, just after the stop of an engine, a crank 3 shaft is rotated reverse up to a predetermined position so as to be ready for the next engine start. Disclosure of Invention 5 For achieving the above-mentioned object, according to the present invention there is provided an engine start control apparatus wherein after the stop of an engine, a crank shaft of the engine is rotated reverse up to a predetermined position so as to be ready for the next engine start, the engine start 10 control apparatus including a starter motor for rotating the crankshaft forward and reverse, reverse rotation controlmeans which starts the supply of electric power for reverse rotation to a starter motor after the stop of an engine, crank angle detecting means for detecting that the crank shaft, when 15 rotating reverse, has reached an angle corresponding to a top dead center of a piston, and reversing load detecting means for detecting a reversing load on the crank shaft, the reverse rotation controlmeans terminating the supply of electric power for reverse rotation in response to the arrival of the crank 20 shaft at the angle corresponding to the top dead center detected by the crank angle detecting means or in response to a rise of the reversing load detected by the reversing load detecting means, whichever is the earlier. According to the above feature, if the crank shaft arrives 25 at the angle corresponding to the top dead center before rise of the reversing load, the position concerned is presumed to be near an exhaust top dead center. Therefore, if the supply of electric power for reverse rotation is stopped in this position, the crank shaft can be further rotated reverse up to just before a compression top dead center (in reverse 5 rotation) with an inertia force. On the other hand, if the. reversing load on the crank shaft rises just before arrival of the crank shaft at the angle corresponding to the top dead center, since the position concerned is already just before the compression top dead 10 center (in reverse rotation) , if the supply of electric power for reverse rotation is stopped at this instant, the crank shaft can be stopped at a position just before the compression top dead center (in reverse rotation) and at which position the compressive reaction force is small. 15 V atc^f^-yf^"€ Brief Description of Drawings Fig. 1 is an entire side view of a scooter type two-wheeled motor vehicle to which the present invention is applied; Fig. 2 is a sectional view of a swing unit shown in Fig. 20 1, taken along a crank shaft; Fig. 3 is a block diagram of a control system for a combined starter/generator; Fig. 4 is a block diagram showing the configuration of a principal portion of an ECU; 25 Fig. 5 is a flow chart of a swing-back control; and Figs. 6(a) to 6(c) are diagrams explaining the operation of the swing-back control. Best Mode for Embodying the Invention The present invention will be described in detail 5 hereinunder with reference to the drawings . Fig. 1 is an entire side view of a scooter type two-wheeled motor vehicle to which an engine start control apparatus for a vehicle according to an embodiment of the present invention is applied. Front and rear portions of a vehicle body are connected 10 together through a low floor portion 4. A body frame serving as a skeleton of the vehicle body is roughly composed of . down-tubes 6 and main pipes 7. A fuel tank and a container box (neither shown) are supported by the main pipes 7 and a seat 8 is disposed thereon. 15 In the front portion of the vehicle body, a handlebar 11 is supported by and above a steering head 5 through a shaft, while a front fork 12 extends downward from the steering head and a front wheel FW is supported through an axle at a lower end of the front fork 12. The handlebar 11 is covered from 20 above with a handlebar cover 13 which also serves as an instrument panel. Brackets 15 are projected from lower ends of rising portions of the main pipes 7 and hanger brackets 18"of a swing unit 2 are respectively connected to and supported by the brackets 15 swingably through link members 16. 25 A single-cylinder four-cycle engine E is mounted on a front portion of the swing unit 2. A belt type continuously 6 variable transmission 10 is constituted backward from the engine E and a reduction mechanism 9 is connected to a rear portion of the continuously variable transmission 10 through a centrifugal clutch, with a rear wheel RW being supported 5 by the reduction mechanism 9 though an axle. A rear cushion 3 is disposed between an upper end of the reduction mechanism 9 and an upper bent portion of a main pipe 7. In the front portion of the swing unit 2 are disposed a carburetor 17 connected to an intake pipe 19 extending from the engine E 10 and an air cleaner 14 connected to the carburetor 17. Fig. 2 is a sectional view of the swing unit 2 taken along a crank shaft 201, in which the same reference numerals or marks as above represent the same or equivalent portions. The swing unit 2 is covered with a crank case 202 which 15 " is constituted by combining left and right crank cases 202L, 202R with each other. The crank shaft 201 is supported rotatably by bearings 208 and 209 which are fixed to the crank case 202R. A connecting rod (not shown) is connected to the crank shaft 201 through a crank pin 213. 20 The left crank case 202L also serves as a belt type continuously variable transmission case and a belt driving pulley 210 is mounted rotatably on the crank shaft 201 which extends up to the left crank case 202L. The belt driving pulley 210 comprises a fixed pulley half 210L and a movable pulley 25 half 210R. The fixed pulley half 210L is fixed to a left end portion of the crank shaft 201 through a boss 211 and themovable 7 pulley half 210R is splined to the crank shaft 201 on the right-hand side of the fixedpulley half 210L so as to be movable toward and away from the fixed pulley half. A V belt 212 is entrained between both pulley halves 210L and 210R. 5 On the right-hand side of the movable pulley half 210R a cam plate 215 is fixed to the crank shaft 201 and a slide piece 215a provided an outer periphery end of the cam plate 215 is slidably engaged with a cam plate sliding boss portion 210Ra formed axially at an outer periphery end of the movable 10 pulley half 210R. The cam plate 215 located on the right-hand side of the movable pulley half 210R has a tapered outer periphery surface inclined toward the movable pulley half 210R and a dry weight ball 216 is accommodated in a space formed between the tapered surface and the movable pulley half 210R. 15 As the rotational speed of the crank shaft 201 increases, the dry weight ball 216 located between the movable pulley half 210R and the cam plate 215 and adapted to rotate together with them moves in a centrifugal direction with a centrifugal force and the movable pulley half 210R is pushed by the dry 20 weight ball 216 and moves leftward, approaching the fixed pulley half 210L. As a result, the V belt 212 sandwiched in between both pulley halves 210L and 210Rmoves in a centrifugal direction and its winding diameter becomes larger. In the rear portion of the "vehicle is provided a driven 25 pulley (not shown) in a corresponding.relation to the belt driving pulley 210 and the V belt 212 is entrained on the driven 8 pulley. With this belt transfer mechanism, the power of the engine E is regulated automatically and is transmitted to a centrifugal clutch.to drive the rear wheel RW through the reduction mechanism 9, etc. 5 A combined starter/generator 1 as a combination of a starter motor and an AC generator is disposed within the right crank case 202R. In the combined starter/generator 1, an outer rotor 60 is fixed with a screw 253 to a tapered front endportion of the crank shaft 201 and an inner stator 50, which is disposed 10 inside the outer rotor 60, is secured to the crank case 202 threadedly with bolts 279. A fan 280 has a central conical portion 280a, a skirt portion of which is fixed to the outer rotor 60 with bolts 246, and the fan 280 is covered with a fan cover 281 through 15 a radiator 282. A sprocket 231 is fixed onto the crank shaft 201 at a position between the combined starter/generator 1 and the bearing 209 and a chain for driving a cam shaft (not shown) from the crank shaft 201 is entrained on the sprocket 231. 20 The sprocket 231 is integral with a gear 232 which is for the transfer of power to a lubricating oil circulating pump. Fig. 3 is a block diagram of a control system for the combined starter/generator 1, in which the same reference numerals as above represent the same or equivalent portions. 25 In an ECU (electric control unit) are provided a three-phase full waver rectifying bridge circuit 400 for full 9 wave-rectifying a three-phase alternating current which is generated by the generator function in the combined starter/generator 1, a regulator 100 which restricts an output of the full wave rectifying bridge circuit 400 to a 5 predetermined regulating voltage (a regulator operating voltage: say 14.5V), and a swing-back controller 700 which causes the crank shaft 201 to rotate reverse up to a predetermined position after turning OFF of the engine. To the ECU are connected a rotor angle sensor 29, an ignition 10 coil 21, a throttle sensor 23, a fuel sensor 24, a seat switch 25, an idle switch 26, a cooling water temperature sensor 27, and an ignition pulser 30, and detection signals are inputted from these portions to the ECU. A spark plug 22 is connected to a secondary side of the ignition coil 21. 15 Further connected to the ECU are a starter relay 34, a starter switch 35, stop switches 3 6 and 37, a stand-by indicator 38, a fuel indicator 39, a speed sensor 40, an auto-by starter 41, and a headlight 42. A dimmer switch 43 is provided in the headlight 42. 20 An electric current is fed to the above various portions from a battery 46 via a main fuse 44 and a main switch 45. The battery 46 is directly connected to the ECU through the starter relay 34, while it has a circuit for connection to the ECU via the main fuse 44 alone. 25 Fig. 4 illustrates the configuration of a main portion related to the swing-back control of the ECU described above. 10 The three-phase full waver rectifying bridge circuit 400 is constituted by paralleling three sets of two series-connected FETs. In a swing-back controller 700, a stage decision unit 5 73 divides one rotation of the crank shaft 201 into thirty-six stages #0~#35 in accordance with an output signal provided from the rotor angle sensor 29 and determines the present stage with a detection timing of a pulse signal as a reference stage (#0). which pulse signal is produced by the ignition pulser 10 30. On the basis of the time required from when the stage decision unit 73 determines a new stage until when it determines the next stage, a stage passing time detector 74 detects a passing time Atn of the stage concerned. A reverse rotation 15 controller 75 issues a reverse rotation drive command on the basis of both the result obtained by the stage decision unit 73 and the passing time Atn detected by the stage passing time detector 74. On the basis of the result obtained by the stage decision 20 unit 73 a duty ratio setting unit 72 controls dynamically the duty ratio of gate voltage to be fed to each power FET in the full wave rectifying bridge circuit 400 . A driver 71 supplies a"drivihg pulse of the thus-set duty ratio to each power FET in the full wave rectifying bridge circuit 400. 25 Next, the operation of the swing-back controller 700 will now be described with reference to a flow chart of Fig. 5 and an operation explaining diagram of Figs. 6(a) to 6(c) . Fig. 6(a) shows a relation between a cranking torque (reversing load) required for rotating the crank shaft 201 reverse and a crank angle. As shown therein, the cranking torque rises 5 abruptly just before a compression top dead center (in reverse rotation) . Fig. 6(b) shows a crank angle - stage relation, and Fig. 6 (c) shows how an angular velocity of the crank shaft changes in reverse rotation. When engine stop is detected in step Sll, reference is 10 made insteps S12 andS13 to the present stage already determined in the stage decision unit 73. If the present stage is any of #0 to #11, the flow advances to step S14, if it is any of #12 to #32, the flow advances to step S15, or if it is any other stage (i.e., any of #33 to #35), the flow advances to 15 step S16. In steps S14 and S16, the duty ratio of the driving pulse is set .at 70%, while in step S15 it is set at 80%, in the duty ratio setting unit 72. As will be described in detail, such a dynamic duty ratio control is made for lowering the angular velocity of the crank 20 shaft 201 sufficiently just before an angle corresponding to the compression top dead center at which the cranking torque increases, in reverse rotation, and for making a quick drive for reverse rotation at any other angle. In step S17, the driver 71 controls each FET in the full 25 wave rectifying bridge circuit 400 at the duty ratio set as above and starts the supply of electric power for reverse rotation. In stepSl8, the passing time A tn of stage #n which the crank shaft has passed is detected by the stage passing time detector 74. In step S19, it is judged in the reverse rotation controller 5 75 whether the crank shaft 201 has passed stage #0, i.e., near the top dead center. In the answer is negative, then in step S21, the ratio of the passing time ▲tn of stage #n which the crank shaft has passed just before to the passing time ▲ tn-1 of stage #(n-l) which the crank shaft has passed before 10 the stage #n is compared with a reference value Rref (4/3 in this embodiment). If this passing time ratio [▲tn/▲tn-1] does not exceed the reference value Rref, the flow returns to step S12 to continue the reverse drive and the above various processings are repeated concurrently. 15 As indicated with a curved line A in Fig. 6(c), if an engine stop position, i.e., a reverse rotation start position, lies on the side closer to the next-time compression top dead center rather than an intermediate position between the last-and next-time compression top dead centers, in other words, 20 if it lies in the course of reaching a compression top dead center after passing an exhaust top dead center (in forward rotation) , the crank shaft can pass stage #0 (exhaust top dead center) despite" the combined starter/generator 1 being reverse-driven at a duty ratio of 70%. That the crank shaft 25 has passed stage #0 is detected in step S19 and then the flow advances to step S20, in which it is judged whether the crank shaft 201 has reached stage #32 . If the answer is affirmative, the. supply of electric power for reverse rotation is stopped in step S22, so that the crank shaft stops after it further rotates reverse with an inertia force. 5 On the other hand, as indicated with a curved line B in Fig. 6(c) , if the reverse rotation start position lies on the side closer to the last-time compression top dead center rather than the intermediate position between the last- and next-time compression top dead centers, in other words, if it lies in 10 the course of reaching the exhaust top dead center after passing a compression top dead center (in forward rotation), since the combined starter/generator 1 is reverse-driven at a duty ratio of 70%, the angular velocity of the crank shaft 201 drops abruptly if the reversing load rises just before reaching stage 15 #0 as shown in Fig.6(a). Further, if it is determined in step S21 that the passing time ratio [▲tn/▲tn-1] is 4/3 or more of the reference value, then in step S22 the supply of electric power for reverse rotation is stopped and the reverse rotation of the crank shaft stops almost simultaneously with 20 the stop of the power supply. Thus, in this embodiment, at the time of reverse drive after stop of the engine it is monitored whether the crank shaft has passed an angle corresponding to a top dead-center and whether the angular velocity of the crank shaft has 25 decreased or not, and the supply of electric power for reverse rotation terminated just after the crank shaft has passed a 4 top dead center in reverse rotation and is also terminated when the angular velocity of the crank shaft has decreased due to an increase of the reversing load, so that the crank shaft, irrespective of a reverse rotation start position, can 5 be returned up to a position just before the last-time compression top dead center (in reverse rotation) and low in compressive reaction force. In this embodiment, moreover, since the angular velocity of the crank shaft 201 is detected on the basis of an output 10 of the rotor angle sensor 29 which detects a rotor angle (i.e., stage) of the combined starter/generator 1, it is not necessary to separately provide a sensor for detecting the angle of the crank shaft 201. Industrial Applicability 15 The following effects are attained by the present invention. (1) If the arrival of the crank shaft at an angle corresponding to a top dead center is detected before a rise of the reversing load on the crank shaft is detected, the 20 position concerned can be presumed to be near an exhaust top dead center, so by stopping here the supply of electric power for reverse rotation the crank shaft can be returned to a desired" position with an inertia"force. If a rise of the reversing load on the crank shaft is 25 • detected before the arrival of the crank shaft at an angle corresponding to a top dead center is detected, the position 15 concerned is just before a compression top dead center (in reverse rotation) and low in compressive reaction force, so by stopping here the supply of electric power for reverse rotation the crank shaft can be stopped at a position of a 5 low compressive reaction force. (2) Since the reverse rotation driving torque of the starter motor is set lower in a top dead center and in the vicinity thereof than in any other position, the angular velocity of the crank shaft which is rotating reverse can be 10 decreased just before a compression top dead center, so that not only the crank shaft can be prevented from exceeding an angle corresponding to the compression top dead center, but also it becomes easier to detect that the crank shaft has reached a position just before the compression top dead center. 15 (3) Since the supply of electric power is stopped just after the crank shaft has passed a top dead center in reverse rotation and thereafter the crank shaft is allowed to further rotate reverse, it is possible to shorten the energization time for the starter motor and hence possible to decrease the 20 amount of electric power consumed. (4) Since the angular velocity of the crank shaft is detected on the basis of an output of the sensor which detects a rotor angle of the starter motor, it is not necessary to-separately provide a sensor for detecting the angle of the 25 crank shaft 201. 16 WE CLAIM: 1. An engine start control apparatus wherein, after the stop of an engine, a crank shaft of the engine is rotated reverse up to a predetermined position so as to be ready for the next engine start, including: a starter motor (1) for rotating the crank shaft (201) forward and reverse; reverse rotation control means (75) which starts the supply of electric power for reverse rotation to a starter motor after the stop of the engine; crank angle detecting means (30,73) for detecting that the crank shaft, when rotating reverse, has reached an angle corresponding to a top dead center of a piston; and reversing load detecting means (74) for detecting a reversing load on the crank shaft, said reverse rotation control means (75) terminating the supply of electric power for reverse rotation in response to the arrival of the crank shaft at the angle corresponding to the top dead center detected by said crank angle detecting means or in response to the rise of the reversing load detected by said reversing load detecting means, whichever is the earlier. 2. An engine start control apparatus as claimed in claim 1, wherein said starter motor includes rotational angle detecting means for detecting a rotational angle of the starter motor, and said change in angular velocity of the crank shaft used by said reversing load detecting means is represented by a change in angular velocity of the starter motor detected by said rotational angle detecting means. 3. An engine start control apparatus as claimed in claim 1 and 2, wherein said engine is a four-cycle engine and said crank angle detecting means is a pulser (30) for ignition which detects an ignition^iming. Dated this 16th day of April, 2002. [RAWW OF REMFR ATTORNEY FOR THE APPLICANTS 17

Documents:

abstract1.jpg

in-pct-2002-00480-mum-2002-abstract-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-cancelled page-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-claims(granted)-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-correspondence(13-06-2007).pdf

in-pct-2002-00480-mum-2002-correspondence-ipo-(26-07-2006).pdf

in-pct-2002-00480-mum-2002-drawing-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-form 1-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-form 18-(24-10-2005).pdf

in-pct-2002-00480-mum-2002-form 2(granted)-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-form 3-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-form 3-(16-04-2002).pdf

in-pct-2002-00480-mum-2002-form 5-(16-04-2002).pdf

in-pct-2002-00480-mum-2002-petiton under rule 137-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-petiton under rule 138-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-power of attoreny-(13-06-2007).pdf

in-pct-2002-00480-mum-2002-power of attoreny-(16-04-2002).pdf

in-pct-2002-00480-mum-abstract(13-06-2007).doc

in-pct-2002-00480-mum-claims granted(13-06-2007).doc

in-pct-2002-00480-mum-form 2 granted(13-06-2007).doc