Starter with improved pinion drive and return structure

Abstract: A pinion moving member (4) on an output shaft (3) is pushed forward by a pinion pushing member (90; 6) such as a lever which is driven by a plunger (40) of an electromagnet switch (5). After a pinion gear (7) of the pinion moving member (4) abuts a ring gear (8), reaction force is stored in a spring (90; 50) as the plunger (40) of the electromagnet switch (5) moves further. When the pinion gear (7) comes into meshing engagement with the ring gear (8) by the reaction force of the spring (90; 50), a retreat restricting member (3c, 81; 9) restricts retreat of the pinion moving member (4). The retreat restricting member (3c, 81; 9) are provided separately from the pinion pushing member (90; 6) so that the the pinion pushing member (90; 6) driven by the electromagnet switch (5) need not restrict the retreat of the pinion moving member (4).

Description: The present invention relates to a starter which starts an engine and, more particularly, to a starter which has a pinion pushing structure and a pinion retreat restricting structure separately for assuring engagement of a pinion gear with an engine ring gear. A starter is known as disclosed in JP-U-5152647. This starter is provided with a tube that is fitted on the outer periphery of an armature rotary shaft through a helical spline and a drive ring that is fitted slidably over the outer periphery of this tube. When a pinion gear has meshed with a ring gear, a ball received in the tube fits in a recess formed in an output shaft. The drive ring regulates the outer periphery of this ball and thereby restricts the ball from being drawn off from the recess, whereby it is possible to restrict the retreat of the pinion. On the other hand, after the engine is started, the drive ring moves on and along the outer periphery of the tube and as a result ceases to regulate the ball, with the result that the ball having been regulated is drawn off from the recess due to the centrifugal force to thereby enable the retreat of the pinion gear. However, in this starter, since a one-way clutch is interposed between the tube receiving the ball therein and the pinion gear, even when the pinion gear is rotated at high speeds by the ring gear after the start of the engine, the rotation of the pinion gear is not transmitted to the tube and the tube is rotated in synchronism with the rotary shaft. That is, since the rotation of the tube is small compared to the rotation of the pinion gear, the centrifugal force that acts on the ball is also small, with the result that the ball becomes unlikely to get off from the recess, whereby insufficient return of the pinion gear occurs. Another conventional starter is known as disclosed in JP-A-58178865. In this starter, a pinion gear and a one-way clutch are separated so that only the pinion gear may move along an output shaft. This starter is so constructed that, after the pinion gear is moved to the side end of a ring gear by the operational force (attraction force) of an electromagnet switch, the pinion gear is engaged with the ring gear by the reaction force stored in an engagement biasing spring force. This construction greatly reduces a mass weight of a moving member which is moved by the electromagnet switch and the engagement biasing spring, in comparison with a starter having the construction in which a pinion gear and a one-way clutch are moved together. As a result, the loading to the engagement biasing spring and the attraction force of the electromagnet switch can be reduced, thus advantageously reducing the electromagnet switch in size. Particularly in a reduction type starter in which the rotation of an electric motor is speed-reduced to be transmitted to an output shaft, the loading to an engagement biasing spring can be reduced more greatly because the pinion gear starts to rotate slowly. In the starter so constructed that the pinion gear and the one-way clutch are separated to move only the pinion along the output shaft, however, a pinion gear retreating force will exert on the teeth of helical splines formed respectively on the inner periphery of the pinion gear and the outer periphery of the output shaft when the ring gear rotation speed exceeds the pinion gear rotation speed due to rotation speed variations caused at the time of driving the engine. The loading onto the engagement biasing spring restricts the retreat of the pinion gear. Therefore, with the loading of the engagement biasing spring being smaller than the retreat force exerting on the pinion gear, the engagement of the pinion gear with the engine ring gear is released before the engine starts combustion thus causing misfires. Even though the loading on the engagement biasing spring can be reduced to reduce the electromagnet switch in size, the reduction in the loading on the engagement biasing spring is limited due to necessity for restricting the retreat of the pinion gear. Thus, great advantage cannot be provided in the reduction in size of the electromagnet switch. Another conventional starter, from which the present invention starts from, is known as disclosed in Patent Abstracts of Japan, Vol.8, No. 20, (M-271), corresponding to JP-A-58178867. In this known starter a pinion consists of a ring-shaped groove opened in the outer circumferential direction, radial holes opened from the groove toward the center, a clutch inner and a pair of bushes press fitted into a bore of the pinion. The pinion is slided on a motor shaft for engagement with and disengagement from a ring gear. The ring-shaped groove is formed at an extension of the clutch inner and has therein balls and a plate spring. A locking and unlocking means for the pinion is so set that the plate spring is forced outward by the centrifugal force of the inertia of the balls and weights when the pinion is turned by the ring gear at a speed at which complete ignition of an engine is caused, the balls come out of the groove, and the entire body of a clutch is returned. In case of this known starter pinion and clutch are a unitary member. This unitary construction of pinion and clutch leads to the drawback that the mass to be moved and thus inertia of the pinion is increased in a disadvantageous way. High mass and inertia necessitates a higer force for moving the pinion towards an engagement position with the ring gear and thus to the necessity of a stronger and accordingly more bulky electromagnet. The present invention has an object to provide a starter which obviates the foregoing drawbacks of the conventional starter. Solution of this object is achieved by what is claimed in claim 1. The present invention provides a starter which has a structure for restricting the insufficient return of a pinion gear after an engine start. The present invention further provides a starter in which loading onto a spring for producing biasing force to engage a pinion gear with a ring gear can be reduced so that an electromagnet switch may be reduced in size. According to the present invention, a starter is provided comprising: an electric starting motor; an output shaft driven by the starting motor through a one-way clutch provided for transmitting a rotation in only one direction; a pinion moving member movably fitted on the output shaft and engageable with an engine ring gear; an electromagnet switch; and pinion pushing means having a lever engaged with the electromagnet switch at one end thereof. This known starter is furthermore characterized in that the pinion moving member is movable in an axial direction relative to the one-way clutch and in that a ball bearing is disposed to be driven by the electromagnet switch through the lever for advancing and returning the pinion moving member axially to and from the ring gear, the ball bearing including an inner ring engaged with the pinion moving member, an outer ring engaged with the lever and a bearing ball disposed between the rings to cause only the inner ring to rotate with the pinion moving member. Preferably, the starter is so constructed that, when a hollow cylindrical member of a pinion moving member is moved by a prescribed distance and as a result a pinion gear meshes with an engine ring gear, an engagement member engaged with a retaining portion formed on an output shaft is retained by the hollow cylindrical member that rotates integrally with the pinion gear. When the pinion gear is rotated at high speeds by the ring gear after the engine is started, the hollow cylindrical member also rotates at high speeds integrally with the pinion gear. Thus, when the regulation of the engagement member by a regulation member is released, the centrifugal force that occurs due to the high speed rotation of the hollow cylindrical member acts on the engagement member, with the result that the engagement member can reliably be disengaged from a retaining portion. As a result of this, after the start of the engine, the pinion gear can retreat on the output shaft along a helical spline and return to its rest position. Preferably, a stepped portion extends from a large diameter portion on the output shaft to a small diameter portion thereon. Thus, the necessity of forming a recess in the output shaft in which the engagement member fits as in the prior art is eliminated. Preferably, the pinion moving member is structurally arranged to move through a ball bearing, relative rotations occur between an inner and an outer rings when the hollow cylindrical member rotates jointly with the pinion gear. That is, even when the inner ring fitted over the outer periphery of the hollow cylindrical member rotates at high speeds after the engine is started, the outer ring can stay at rest, with the result that no slide friction occurs between the outer ring and a pinion driving lever. Thus, the lever is required merely to have only a rigidity high enough to advance and retreat the pinion through the ball bearing. Furthermore, in the starter in which a reaction force stored in a spring is transmitted to a pinion pushing member to engage a pinion gear with a ring gear when rotating force of an electric starting motor is transmitted to an output shaft and the pinion gear rotates to a position where the pinion gear engages the ring gear, a pinion retreat restricting member is provided for restricting in cooperation with a plunger the pinion gear from retreating after the meshing engagement of the pinion gear with the ring gear. Thus, even when retreating force exerts on the pinion gear due to rotation speed variations caused at the time of driving an engine, the pinion gear can be restricted from retreating by the pinion retreat restricting member. That is, because the pinion pushing member on which the reaction force of the spring exerts is not required to restrict the retreat of the pinion gear, the spring loading can be reduced greatly and the electromagnet switch can be reduced in size in comparison with a conventional starter in which retreat of a pinion gear is restricted by loading to an engagement biasing spring. Preferably, the starter is provided further with a speed reduction mechanism for reducing rotation of the electric starting motor to transmit the same to the output shaft. Thus, in comparison with a starter having no reduction mechanism, the pinion gear starts to rotate slowly and the loading of the spring can be reduced more. Further advantageous aspects of the invention are subject-matter of the subclaims. The present invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings, in which: Fig. 1 is a side view illustrating, partly in cross section, a starter according to the present invention; Fig. 2 is a partial sectional view illustrating a pinion disengagement restriction mechanism used in the starter shown in Fig. 1; Fig. 3 is a front view illustrating a lever and a ball bearing used to drive a pinion in the starter shown in Fig. 1. DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS A starter 1 is composed of, as shown in Fig. 1, an electric starting motor 2 that generates a rotating force upon receipt of electric power, an output shaft 3 that rotates upon receipt of the rotating force of the motor 2, a pinion moving member 4 that is fitted onto an outer periphery of the output shaft 3 through a helical spline 3b, a planetary gear reduction mechanism (described later) for reducing the rotating speed of the motor 2 to cause an increase in the rotating torque, a one-way clutch (described later) for transmitting to the pinion 3 the rotating force of the motor 2 that has been transmitted thereto through the planetary gear reduction mechanism, pinion driving member (described later) for moving the pinion moving member 4 toward a ring gear 8 of the engine, etc. The motor 2 is composed of an armature 16 that rotates integrally with an armature rotary shaft 19, fixed magnetic poles (e.g., permanent magnets) 15 that are disposed around this armature 16, a cylindrical yoke 12 that fixes the fixed magnetic poles 15 to an inner peripheral surface thereof, etc. The rotary shaft 19 is rotatably supported on a forward end side of the armature 16 by a supporting member 80 through a ball bearing 19a and is rotatably supported on a rearward end side of the armature 16 by a rear casing 14 through a bearing not illustrated. It is to be noted that the supporting member 80 is provided as a partitioning wall for making a partition between the motor 2 and the planetary gear reduction mechanism and a cylindrical extended wall portion 80a that is formed on the outer periphery thereof is supported by inner peripheral surfaces of a front casing 10 and the yoke 12. The output shaft 3 is disposed on the same axis as that of the rotary shaft 19 and a forward end portion thereof is rotatably supported by the front casing 10 through a bearing 33 while, on the other hand, a rearward end portion thereof rotatably supports through a bearing 28 a forward end of the rotary shaft 19 in a recess that is formed in a central part of the end face thereof. This output shaft 3 is formed such that a forward side thereof, as viewed in the axial direction thereof, where the helical spline 3b is formed to be smaller in diameter than a rearward side thereof and thereby has a tapered stepped wall surface 3c that extends from a terminal end of the helical spline 3b to the outer peripheral surface of the rearward side thereof. The pinion moving member 4 has integrally provided on the side of a rear end thereof a hollow cylindrical member 70 that is fitted over the outer peripheral surface of the rearward side of the output shaft 3 and is so provided as to be axially movable, along with the hollow cylindrical member 70, on the output shaft 3 along the helical spline 3b of the output shaft 3. However, the advance or forward movement of the pinion moving member 4 is regulated by abutting against a stop collar 71 that is fixed through a snap ring 61 onto the outer periphery of the forward end side of the output shaft 3. Also, the retreat movement of the pinion moving member 4 is regulated by a tapered stepped portion 3c between an inner peripheral surface of the pinion moving member 4 and an inner peripheral surface of the hollow cylindrical member 70 abutting against the stepped wall surface 3c of the output shaft 3 (a state illustrated in Fig. 1). The hollow cylindrical member 70 has openings (that may be one in number) 70a formed at a plurality of circumferential positions thereof in such a manner that these openings pass through a wall surface thereof, a ball 81 being received in each of the openings 70a. The ball 81 has a diameter that is larger than the thickness of the wall surface of the hollow cylindrical member 70 and is received in the opening 70a in a state of being movable radially of the hollow cylindrical member 70. It is to be noted that the opening 70a that receives the ball 81 therein is formed at a position (hereinafter referred to as "the terminal end portion of the helical spline 3b") where when the pinion moving member 4 advances and abuts against the stop collar 71, i.e., when the pinion moving member 4 has meshed with the ring gear 8 the ball 81 drops from the outer peripheral surface of the rearward side of the output shaft 3 to the outer peripheral surface of the forward side of the output shaft 3 and thereby abuts against the stepped wall surface 3c of the output shaft 3. Also, the provision of the opening 70a is made so that, at this time, that is, when the ball 81 has dropped into the terminal end portion of the helical spline 3b, the ball 81 may be restricted from being drawn off from the outer peripheral surface of the hollow cylindrical member 70 and so that a ball bearing 91 as described later may be slid on the outer peripheral surface of the hollow cylindrical member 70. The planetary gear reduction mechanism is composed of a sun gear 26 that is formed on the outer periphery of a forward end of the rotary shaft 19, a plurality of planetary gears 28 (e.g., three pieces) that mesh with this sun gear 26, and an internal gear 27 that meshes with each of the planetary gears 28. The sun gear 26 rotates integrally with the rotary shaft 19 to thereby transmit the rotation thereof to each planetary gear 28. Each planetary gear 28 is rotatably supported by a corresponding pin 31 through a bearing 32 and revolves around an outer periphery of the sun gear 26 while being meshed with both the sun gear 26 and the internal gear 27. The internal gear 27 is fixed, for example, by press-fitting, to the inner peripheral surface of an extended wall portion 80a that is provided on the outer periphery of the supporting member 80 to thereby enable the revolution of each planetary gear 28. The one-way clutch is composed of a clutch outer member 63, clutch inner member 62, clutch rollers 30, clutch cover 82, etc. The clutch outer member 63 is provided integrally with the pins 31 and, when the revolving force of each planetary gear 28 has been transmitted thereto through the pins 31, rotates jointly with each planetary gear 28. The clutch inner member 62 is one which has been provided by the rearward end portion of the output shaft 3 being radially enlarged, and is caused to rotate by the rotating force of the clutch outer member 63 being transmitted thereto through the clutch rollers 30 at the time of the torque transmission. It is to be noted that the clutch outer member 63 and the pins 31 may be provided separately from each other, after which the pin 31 is forcedly inserted into and fixed to the clutch outer member 63 or the both members are bonded together. In this one-way clutch, when the revolving force of each planetary gear 28 is transmitted to the clutch outer member 63 through the pins 31, the clutch rollers 30 connect the clutch outer member 63 and the clutch inner member 62, whereby the rotating force of the clutch outer member 63 is transmitted to the clutch inner member 62. This enables the transmission of the rotating force of the motor 2 to the output shaft 3. On the other hand, when the pinion moving member 4 rotates at high speeds by receiving the rotating force of the engine through the ring gear 8 after the start of the engine, the rotation speed of the clutch inner member 62 becomes higher than the rotation speed of the clutch outer member 63, with the result that the clutch rollers 30 disconnect the clutch outer member 63 and the clutch inner member 62. As a result, the rotation of the clutch inner member 62 is restricted from being transmitted to the clutch outer member 63. This enables the restriction of the overrun of the armature 16. The pinion driving mechanism is composed of an electromagnet switch 5, a lever 90 and the ball bearing 91. The electromagnet switch 5 is provided with an attraction coil (not illustrated) that generates a magnetic force upon receipt of electric current and a plunger 40 that is disposed in the hollow interior of the coil. When a starter switch not illustrated is turned on whereby the electric current is supplied to the coil, the electromagnet switch 5 attracts the plunger 40 by the magnetic force that generates in the coil. As a result, by the swing operation of the lever 90 through a joint 40a that is provided on a forward end of the plunger 40, the electromagnet switch 5 generates a force of pushing the pinion moving member 4 forward. Further, even when the pinion moving member 4 that has been pushed forward abuts against the ring gear 8 and has its advance movement thereby restricted, the lever 90 itself is flexed with the result that the plunger 40 is attracted whereby it is possible to close motor contacts (not illustrated) that is provided inside the switch 5. It is to be noted that since the magnetic force of the coil attracting the plunger 40 disappears when supply of the electric current to the coil is stopped, the plunger 40 that has been attracted is returned to its initial position (the position illustrated in Fig. 1) by a return spring not illustrated. The lever 90 has one end that is connected to the joint 40a and the other end that is engaged with an outer ring 91a from right and left sides of the ball bearing 91 (Figs. 2 and 3), whereby the lever 90 is provided so as to be swingable about a pin 93 as a fulcrum that is supported by the front casing 10. By its inner ring 91b being fitted over the outer peripheral surface of the hollow cylindrical member 70, the ball bearing 91 is provided so as to be slidable (between the position at which a forward end surface of the ball bearing 91 abuts on a rearward end surface of the pinion moving member 4 and the position at which a rearward end surface of the ball bearing 91 abuts on a snap ring 94 that is mounted on the rearward end portion of the hollow cylindrical member 70) on and along the outer peripheral surface of the hollow cylindrical member 70 in the axial direction thereof. In the inner peripheral surface of the inner ring 91b of the ball bearing 91, from the pinion moving member 4 side end surface thereof to an intermediate position thereof as viewed in the axial direction thereof, there is formed a recess 91c which is intended, when the pinion moving member 4 is located at its rest position (Fig. 1), to retain the outer peripheral portion of the ball 81 that protrudes from the outer peripheral surface of the hollow cylindrical member 70. Also, in the outer peripheral surface of the outer ring 91a, there is formed a groove 91d over an entire circumference thereof, with which the other end of the lever 90 is engaged. It is to be noted that the ball bearing 91 not only forms a part of the pinion driving mechanism but also forms a part of the pinion disengagement restriction mechanism or pinion retreat restricting mechanism together with the hollow cylindrical member 70, ball 81 and stepped wall surface 3c of the output shaft 3. The embodiment operates as follows. When the starter switch is turned on whereby electric current is supplied to the coil of the electromagnet switch 5, the plunger 40 is attracted by the magnetic force of the coil (moved to the right side in Fig. 1). When this plunger attraction force is transmitted to the ball bearing 91 through the lever 90, it is transmitted to the hollow cylindrical member 70 as the pinion pushing-forward force through the ball 81 that is retained by the recess 91c of the ball bearing 91 (inner ring 91b) and the opening 70a of the hollow cylindrical member 70. As a result, the pinion moving member 4 that is integrated with the hollow cylindrical member 70 is caused to advance on the output shaft 3 along the helical spline 3b together with the hollow cylindrical member 70. When the pinion moving member 4 that has advanced on the output shaft 3 abuts against the ring gear 8, the motor contacts inside the electromagnet switch 5 are closed whereby electric current is supplied to the armature 16, with the result that the rotating force generates in the armature 16. By the rotating force of this armature 16 being transmitted to the output shaft 3 through the planetary gear reduction mechanism and one-way clutch, the output shaft 3 rotates. As a result, the pinion moving member 4 that has come into abutment with the ring gear 8 rotates and intermeshes with the ring gear 8 through its teeth traces coming into coincidence with the teeth traces thereof. The ball 81 drops onto the terminal end portion of the helical spline 3b in synchronism with this intermeshing engagement of the pinion moving member 4 with the ring gear 8. Since the engagement between the ball 81 and the recess 91c formed in the inner ring 91b of the ball bearing 91 is released, the ball bearing 91 that is kept receiving the pinion pushing-forward force further advances on and along the outer peripheral surface of the hollow cylindrical surface until it abuts against the rearward end surface of the pinion gear 7 and stops. At this time, as illustrated in Fig. 2, the open surface of the opening 70a that is formed in the hollow cylindrical member 70 is closed by the inner peripheral surface of the inner ring 91b. Therefore, it is possible to restrict the ball 81 that is allowed to drop on the terminal end portion of the helical spline 3b from popping out from the opening 70a. As a result, when the force of retreating the pinion moving member 4 acts thereon through the ring gear 8 after the start of the engine, since the retreat movement of the hollow cylindrical member 70 is regulated by the stepped wall 3c of the output shaft 3 through the ball 81, the retreat of the pinion moving member 4 is restricted thereafter. When the electric current ceases to be supplied to the electromagnet switch 5 after the start of the engine, the magnetic force of the coil disappears with the result that the plunger attraction force also disappears. As a result, the ball bearing 91 that has been pushed forward is returned through the lever 90. Here, when the recess 91c that is formed in the inner ring 91b is returned to the position coinciding with the open surface of the opening 70a, due to the centrifugal force of the hollow cylindrical force that rotates at high speeds the ball 81 is drawn off from the terminal end portion of the helical spline 3b and thereby is received in the opening 70a and recess 91c. Since as a result of this the engagement of the ball 81 with the stepped wall surface 3c is released, the retreat movement of the pinion moving member 4 becomes possible, with the result that the pinion moving member 4 can be returned to the rest position illustrated in Fig. 1. As described above, the starter 1 of this embodiment is provided with the pinion disengagement restriction means on the pinion moving member side from the one-way clutch. That is, the ball 81 is received in the opening 70a of the hollow cylindrical member 70 that is provided integrally with the pinion moving member 4. For this reason, since after the start of the engine the hollow cylindrical member 70 also rotates at high speeds integrally with the pinion moving member 4 that is rotated by the ring gear 8, if the ball bearing 91 is moved whereby the ball 81 can pop out, the centrifugal force resulting from the high speed rotation of the hollow cylindrical member 70 acts on the ball 81, with the result that the ball 81 can reliably be released from the terminal end portion of the helical spline 3b. As a result of this, after the engine is started, the pinion moving member 4 can retreat on the output shaft 3 along the helical spline 3b and thus can be returned to its rest position. Also, since it is structurally arranged to move the pinion moving member 4 through the ball bearing 91, when the hollow cylindrical member 70 has rotated jointly with the pinion moving member 4, the inner ring 91b and outer ring 91a of the ball bearing 91 rotate relative to each other. That is, after the engine is started, even when the inner ring 91b that is fitted over the outer periphery of the hollow cylindrical member 70 rotates at high speeds, the outer ring 91a can be kept out of rotation. Therefore, no slide friction occurs between the outer ring 91a and the lever 90. Therefore, since it is sufficient for the lever 90 merely to have only a rigidity high enough to advance and retreat the pinion moving member 4 through the ball bearing 91, an inexpensive lever such as a wire material can be used as the lever 90. Further, since the retreating force that acts on the pinion moving member 4 can be received by the stepped wall surface 3c of the output shaft 3 through the ball 81, the necessity of forming a fitting hole in which the ball 81 is fitted in the output shaft 3 as in the prior art is eliminated. (Modifications of First embodiment) Although in the present embodiment it has been arranged, when the pinion moving member 4 has been meshed with the ring gear 8, for the ball 81 to drop onto the terminal end portion of the helical spline 3b, i.e., the stepped wall surface 3c, it may be arranged to form in the output shaft 3 the fitting hole in which the ball 81 is fitted.

Claims: A starter comprising: an electric starting motor (2); an output shaft (3) driven by the starting motor through a one-way clutch (30, 62, 63) provided for transmitting a rotation in only one direction; a pinion moving member (4) movably fitted on the output shaft and engageable with an engine ring gear (8); an electromagnet switch (5); and pinion pushing means (90, 91) having a lever (90) engaged with the electromagnet switch at one end thereof; characterized in that the pinion moving member (4) is movable in an axial direction relative to the one-way clutch (30, 62, 63), and in that a ball bearing (91) is disposed to be driven by the electromagnet switch through the lever for advancing and returning the pinion moving member (4) axially to and from the ring gear (8), the ball bearing including an inner ring (91b) engaged with the pinion moving member, an outer ring (91a) engaged with the lever (90) and a bearing ball disposed between the rings to cause only the inner ring to rotate with the pinion moving member (4). The starter according to claim 1, wherein said electromagnet switch (5) has a plunger (40) and is constructed to control power supply to the electric motor in response to movement of the plunger. The starter according to claim 1 or 2, wherein said pinion moving member (4) carries a pinion gear (7) at its outer periphery and is fitted on an outer periphery of the output shaft through a helical spline (3b) to mesh with the ring gear (8) of the engine and to transmit the rotating force of the electric motor to the ring gear. The starter according to claim 3, wherein pinion retreat restricting means (3c, 81) are provided separately from the pinion pushing means for restricting the pinion gear (7) from retreating after the meshing engagement of the pinion gear with the ring gear (8). The starter according to claim 4, wherein the pinion retreat restricting means (3c, 81) is disposed movably toward a rear side of the pinion gear (7), said rear side is axially opposite to the ring gear (8). The starter according to anyone of claims 2 to 5, wherein the pinion pushing means (90, 91) and the pinion retreat restricting means (3c, 81) are both disposed to be responsive to the movement of the plunger (40). The starter according to anyone of claims 1 to 6, wherein the pinion pushing means (90, 91) are disposed to be moved further after the pinion retreat restricting means (3c, 81) are moved to a position for restricting the pinion gear (7) from retreating. The starter according to anyone of claims 1 to 7, wherein the pinion pushing means (90, 91) includes said resilient lever (90) disposed rotatably around a predetermined fulcrum (93) and having one end coupled to the plunger (40) and another end operatively coupled to the pinion gear (7) so that the another end is movable forward axially beyond a position where the pinion retreat restricting means (3c, 81) restricts the retreat of the pinion gear (7). The starter according to anyone of claims 4 to 8, wherein the pinion retreat restricting means (3c, 81) includes a stepped wall (3c) formed on the output shaft (3) and a ball (81) disposed axially movably on the output shaft in response to movement of the another end of the lever (90), so that the ball restricts the pinion gear (7) from retreating when moved to and engaged with the stepped wall. The starter according to claim 8 or 9, wherein the ball bearing (91) is engaged with the another end of the lever so that the lever is held unrotatably relative to the output shaft (3). The starter according to anyone of claims 4 to 10, wherein the pinion retreat restricting means further includes a hollow cylindrical member (70) provided on the outer periphery of the output shaft and axially movable integrally with the pinion gear (7) and rotatable, said ball (81) being retained by the hollow cylindrical member, said stepped wall (3c) being engageable with the ball, when the hollow cylindrical member moves a prescribed distance to thereby stop the retreat of the hollow cylindrical member, and said ball bearing (91) regulates the radial movement of the ball, when same is engaged with the stepped wall and thereby restricts the ball from being disengaged from the stepped wall. The starter according to claim 11, wherein the output shaft (3) has a small diameter portion smaller in diameter than a large diameter portion over which the hollow cylindrical member (70) is normally fitted, wherein the stepped wall (3c) extends from the large diameter portion to the small diameter portion. The starter according to anyone of claims 1 to 12, wherein the ball bearing (91) is fitted over an outer peripheral surface of the hollow cylindrical member (70) and is provided so as to be axially slidable on and along the outer peripheral surface of the hollow cylindrical member; and the pinion pushing means (90, 91) is adapted to move the pinion moving member (4) through the ball bearing. The starter according to anyone of claims 1 to 13, wherein a speed reduction mechanism (26, 27, 28) is provided for reducing rotation of the electric motor to transmit the same to the output shaft (3). The starter according to claim 11, wherein the hollow cylindrical member (70) has an opening (70a) for receiving the ball (81) therein radially movably; and the pinion pushing means (90, 91) has a recess (91c) at a radially inner side thereof facing the cylindrical member (70) for contacting the ball to move the pinion moving member (4) axially.

Inventors: HAYASHI NOBUYUKI, KAJINO SADAYOSHI, SOH MASAHIRO, HAYASHI, NOBUYUKI , KAJINO, SADAYOSHI, SOH, MASAHIRO
Applicants: DENSO CORP, DENSO CORPORATION
Application year: 1997
Main classification: F02N15
IPC codes: F02N15, F02N11