Starter having a pinion movement control structure

Abstract: A starter (1) has a motor (2), output shaft (3) driven by the motor, a pinion moving body (4) mounted on the output shaft and engageable with a ring gear (29), an electromagnet switch (5), and a rotation restricting member (6) driven by the electromagnet switch to engage and restrict rotation of the pinion moving body until engagement of a pinion gear (30) with the ring gear. To protect the pinion rotation restricting member, continued engagement of the rotation restricting member with the pinion moving body is released by a guide (7c, 47e) when the pinion moving body rotates a predetermined angle. Further, to protect the pinion moving body, the pinion moving body is advanced closely to the ring gear and thereafter the motor is allowed to rotate so that the pinion engages the ring gear at low rotation speeds.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates a starter having a pinion movement control structure. 2. Description of Related Art: Small-sized and lightweight starters are proposed in Japanese Patent Application Laid-Open No. 8-93607 and No.50-5807. The starter has a starting motor, an output shaft driven by the starting motor, a pinion spline-fitted on the output shaft, and a pinion rotation restricting member which restricts the rotation of pinion to advance the pinion axially on the output shaft through the helical spline fitting by a rotation difference relative to the output shaft. In this type of starter, it is often encountered that even when the pinion reaches the end side of the ring gear of an engine, the pinion fails to mesh with the ring gear for one reason or another. This may occur at the time of restarting the starter while the pinion is still in the course of inertia rotation which exists immediately after starting the starter. At this time, the pinion rotation restricting member still kept engaged with the pinion is pulled toward the pinion rotation direction. Thus, the pinion rotation restricting member is subjected to extreme deformation and may possibly break down. Further, while the pinion is moving on the output shaft toward the ring gear, the starting motor picks up rotation speed rapidly thereby causing a large impact upon meshing of the pinion with the ring gear. Therefore, sufficient rigidity to withstand impact is required for a rotational force transmission part of the starter including the pinion. In document EP-A-0 702 150 there is disclosed a starter for an engine having a ring gear, wherein the starter comprises a starting motor for generating rotating force; an output shaft for rotating as driven by the starting motor; a pinion moving body fitted movably on the output shaft through helical splines, the pinion moving body having a pinion gear on a front part thereof for meshing with a ring gear of an engine and having protrusions and recesses on an entire periphery of a rear part thereof; a rotating restricting member having an engagement part engageable with the protrusions and recesses to elastically restrict rotation of the pinion moving body while the engagement part is in engagement with the protrusions and the recesses; moving means to move the engagement part of the rotation restricting member to the protrusions and recesses. The engagement part is disengaged from the pinion moving body at that point, when the pinion gear meshes with the ring gear. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a starter which avoids extreme deformation of a pinion rotation restricting member when a pinion fails to mesh with a ring gear. This object is solved by a starter according to claim 1. Further advantageous modifications of the present invention are subject-matters of the sub-claims. According to the present invention, for attaining the object, there is provided a structure by which a pinion rotation restriction member is disengaged from a pinion moving member upon rotation of the pinion moving member by a predetermined angle from an initial engagement position. BRIEF DESCRIPTION OF THE DRAWINGS Other objects, features and advantages of the present invention will become more apparent from the following detailed description which is to be read with reference to the accompanying drawings, in which: Fig. 1 is a sectional view of a starter according to the first embodiment of the present invention; Fig. 2 is a perspective view of a pinion movement control structure according to the first embodiment; Fig. 3 is a plan view of a plate used in the pinion movement control structure; Figs. 4A - 4F are explanatory views illustrating operation process of the pinion movement control structure; Fig. 5 is an electric circuit diagram of a starter according to the first embodiment; Fig. 6 is a side view showing a pinion movement control structure according to the second embodiment of the present invention; Fig. 7 is a perspective view showing the shape of protrusions and recesses of a pinion moving body used in the second embodiment; Fig. 8 is a sectional view showing the non-operating state of the pinion movement control structure according to the second embodiment; Fig. 9 is a sectional view showing the operating state of the pinion movement control structure according to the second embodiment; Fig. 10 is a perspective view showing the operation of the pinion movement control structure in the first and the second embodiments; Fig. 11 is a side view showing variations of the spacing between the pinion moving body and the ring gear in the first and the second embodiments; Fig. 12 is a side view showing variations of the spacing between the pinion moving body and the plate in the first and the second embodiments; Fig. 13 is a side view showing variations of the spacing between the pinion moving body and the plate in the first and the second embodiments; Fig. 14 is a side view showing a pinion movement control structure according to the third embodiment of the present invention; Fig. 15 is a plan view of a pinion retreat restricting member used in the third embodiment; Figs. 16A and 16B are a side view and a bottom view of the pinion retreat restricting member shown in Fig. 15; Fig. 17 is a perspective view showing a state of the upper protrusion in contact with a protuberant surface in the third embodiment; Fig. 18 is a plan view showing a movement of the upper protrusion in the third embodiment; Fig. 19 is a side view showing variations of spacing between the pinion moving body and pinion retreat restricting member in the third embodiment; Fig. 20 is a side view showing variations of spacing between the pinion moving body and the pinion retreat restricting member in the third embodiment. DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS The present invention will be described with reference to various embodiments shown in the drawings. (First Embodiment) In this embodiment, as shown in Fig. 1, a starter 1 is made up of a starting motor 2 for generating a rotational force, a planetary reduction gear (described below) for decelerating rotation of the starting motor 2, an output shaft 3 for rotating upon receiving the rotational force of the reduction gear, a pinion moving body 4 fitted onto the output shaft 3, an electromagnet switch 5 for controlling current sully to the starting motor, a rotation restricting member 6 (Fig. 2) for restricting rotation of the pinion moving body 4 before the starting motor 2 starts rotating, and a plate 7 (Fig. 3) to release restriction on the rotation of the pinion moving body 4 applied by the rotation restricting member 6. The starting motor 2 is constructed by a cylindrical yoke 8 forming a magnetic frame, a fixed magnetic pole 9 (e.g., a plurality of permanent magnets) secured to an inner periphery of the yoke 8, an armature 10 rotatably disposed inside the inner periphery of the fixed magnetic pole 9, and brushes 12 in sliding contact with a commutator 11 provided at the rear end side of the armature 10 (right end side in Fig. 1). One end of a rotation shaft of the armature 10 is rotatably supported via a bearing 15 held by a separating plate 14 which separates the armature 10 from the reduction gear while the other end of the rotation shaft 13 is rotatably supported via a bearing 17 held by a partition 16 which separates the armature 10 from the electromagnet switch 5. The reduction gear is composed of a sun gear 18 (outer teeth) formed around the outer periphery on one end side of the rotation shaft 13, an internal gear 19 (inner teeth) positioned radially outside the sun gear 18, a plurality of planetary gears 20 which are interposed between the sun gear 18 and the internal gear 19 in mesh with both gears 18 and 19, and a carrier 21 rotatably supporting the planetary gears 20 through pins 24. The internal gear 19 is formed on the internal periphery of a gear forming member 23 subjected to rotational restriction on the internal periphery of a front housing 22. The planetary gears 20 are rotatably supported via respective bearings 25 inserted onto the outer periphery of the pins 24 which are pressed into the carrier 21. The carrier 21 is positioned radially outside the rear end of the output shaft 3. Rollers 26 are placed between the carrier 21 and the rear end of the output shaft 3, forming a one-way clutch with the rear end of the output shaft 3 and the rollers 26. This one-way clutch transmits the rotation output of the reduction gear via the rollers 26 to the output shaft 3. The output shaft 3 is coaxially arranged with the rotation shaft 13. The output shaft 3 has one end thereof rotatably supported via a bearing 27 which is supported by the front housing 22, and the other end rotatably supported via a bearing 28 which is supported by an inner cylindrical part 23a of the gear forming member 23. On the outer periphery between both bearings 27 and 28 of the output shaft 3, there is formed a helical spline 3a, onto which a helical spline 4a formed in the internal periphery of the pinion moving body 4 is fitted. The pinion moving body 4 includes a pinion gear 30 to mesh with a ring gear 29 which is provided on the drive shaft of the engine, and a flange 31 on the rear end side of the pinion gear 30 (right end side in Fig. 1) which has a larger outside diameter than that of the pinion gear 30 and which is formed a multiplicity of protrusions and recesses 31a (Fig. 2) on the outer periphery thereof; a washer 33 (thrust bearing) which is rotatably supported via rollers 32 is disposed on the rear end side thereof. The pinion moving body 4, which is axially movably provided through fitting of the helical spline 3a of the output shaft 3 with the helical spline 4a of the pinion moving body 4, is urged or biased normally toward the rear side of the starter 1 (opposite side of the ring gear 29) by a spring 34 arranged in front of the pinion gear 30. The electromagnet switch 5 is disposed on the rear end of the starter 1 and fixed to the inner periphery of a bowl-shaped rear casing 35. This electromagnet switch comprises an attraction coil 37 which is turned on with the closing of a key switch 36 (Fig. 5) and a plunger 38 movably provided in the inner periphery of the attraction coil 37. The movement of the plunger 38 is followed by the making and breaking of a motor contact (explained below) interposed in an electric circuit (Fig. 5) of the starting motor 2. It is to be noted that the attraction coil 37 and the plunger 38 are disposed so that the plunger 38 will move in the radial direction of the rear casing 35 (upward and downward directions in Fig. 1). As shown in Fig. 5, the motor contact is made up of a movable contact 39 attached to the upper end of the plunger 38, a battery-side fixed contact 41 integrally constructed with a battery terminal 40 fixed to the rear casing 35, and a motor-side fixed contact 42 connected to the brush 12 (anode side). When the plunger 38 is attracted and moves upward in Figs. 1 and 5, the movable contact 39 comes into contact with both fixed contacts 41 and 42, thereby supplying current from a battery 45. As shown in Fig. 2, the rotation restricting member 6 is formed, for example, by bending a metallic bar member into the shape of a loop with both ends 6a and 6b at radially mutually facing positions being bent at approximately right angles into the same direction. The rotation restricting member 6 is so arranged that a part bent around in the loop shape is provided radially outside the inner cylinder 23a of the gear forming member 23 in a space formed between the plate 7 arranged ahead of the gear forming member 23 and the gear forming member 23 while both ends 6a and 6b bent in the same direction are taken out through the plate 7, the entire assembly being movable in the upward and downward directions in Fig. 1. One end 6a (upper protrusion 6a) is taken out of the radially upper part of the plate 7 (radially outside the outer periphery of the flange 31 of the pinion moving body 4), and the tip thereof is normally positioned ahead of the flange 31. Also, the other end 6b (lower protrusion 6b) is taken out of the radially lower part of the plate 7, and the tip thereof is normally positioned behind the washer 33 of the pinion moving body 4. A spring 43 fixed to the plate 7 is in engagement with the lower protrusion 6b so that the rotation restricting member 6 is normally biased upward in Fig. 1 due to the biasing of the spring 43. It will be noted that the rotation restricting member 6 can be moved downward in Fig. 1 against the biasing of the spring as the operating force of the electromagnet switch 5 (movement of the plunger 38) is transmitted through a bar 44. The bar 44 comprises a moving part 44a engaging the plunger 38 to follow the movement of the plunger 38, an operating part 44b engaging the lower protrusion 6b to operate the lower protrusion 6b, and a straight coupling part 44c connecting the moving part 44a to the operating part 44b. The bar 4 operates as follows: the coupling part 44c extends generally in parallel to the rotation shaft 13 and radially outside the armature 10 and outside the reduction gear, while the coupling part 44c is rotatably supported by two bearings (not illustrated) so that as the moving part 44a moves following the plunger 38, such movement is converted to rotational movement of the coupling part 44c, thus enabling the operating part 44b to move the lower protrusion 6b downward. As shown in Fig. 3, the plate 7 is provided substantially in a circular form subject to rotational restriction with respect to the front housing 22 by means of projections 7a formed at two locations on the outer periphery. This plate 7 has an opening or slot 7b through which the upper protrusion 6a is taken out and another slot (not illustrated) through which the lower protrusion 6a is taken out. The slot 7b from which the upper protrusion 6a is taken out is formed to extend radially inwardly toward the outer periphery of the pinion moving body 4 so that the upper protrusion 6a can move as being pulled down by rotation of the pinion moving body 4 while still being engaged with the protrusions and recesses 31a of the flange 31. Also, an incline (guide surface) 7c which, upon rotation of the pinion moving body 4 by the predetermined angle from the position of engagement of the upper protrusion 6a with the protrusions and recesses 31a, disengages the upper protrusion 6a having followed the rotation of the pinion moving body 4 while in engagement with the protrusions and recesses 31a thereof from the protrusions and recesses 31a, as well as a holding part 7d to hold the disengaged upper protrusion 6a are formed in this slot 7b. Next, operation of this embodiment will be explained. Upon closing a key switch 36 (Fig. 5), electric current flows from the battery 45 to the attraction coil 37 of the electromagnet switch 5 to generate a magnetic force, which attracts and moves the plunger 38 upward in Fig. 1. Such movement is transmitted through the bar 44 to the rotation restricting member 6, thereby causing the rotation restriction member 6 to move downward in Fig. 1 while flexing the spring 43 (Fig. 4A). This enables the upper protrusion 6a of the rotation restricting member 6 to engage the protrusions and recesses 31a provided on the outer periphery of the flange 31 of the pinion moving body 4 (Fig. 4B), thus restricting the rotation of the pinion moving body 4 before rotation of the starting motor 2. On the other hand, in the electromagnet switch 5, current flows from the battery 45 to the armature 10 as movement of the plunger 38 makes the movable contact 39 abut both fixed contacts 41 and 42, and the armature 10 starts rotating. Rotation of the armature 10 is first reduced by the reduction gear, then transmitted to the output shaft 3 to cause the output shaft 3 to rotate. This rotation tends to rotate the pinion moving body 4. However, inasmuch as the pinion moving body 4 is subjected to rotation restriction by the rotation restricting member 6, the rotation of the output shaft 3 acts upon the pinion moving body 4 as propulsion due to the fitting of helical splines 3a and 4a. This results in causing the pinion moving body 4 to move axially on the output shaft 3 to let the front end side of the pinion gear 30 of the pinion moving body 4 to come into contact with the rear end side of the ring gear 29. At this instant, the upper protrusion 6a in engagement with the protrusions and recesses 31a of the flange 31 can flex in the rotational direction of the pinion moving body 4, making it possible for the pinion gear 30 to mesh with the ring gear 29 during rotation of the pinion gear 30 at least by one pitch and, again, resulting in causing the pinion moving body 4 to move axially further on the output shaft 3 to let the pinion gear 30 completely mesh with the ring gear 29. Upon completing meshing of the pinion gear 30 with the ring gear 39, the upper protrusion 6a which is in engagement with the protrusions and recesses 31a disengages therefrom and falls behind the washer 33 provided at the rear end side of the pinion moving body 4 to prevent the pinion moving body 4 from retreating. For one reason or another, the pinion gear 30 may fail to mesh with the ring gear 29. This may happen, for example, when the starting motor 2 is restarted immediately after interruption of current supply to the starting motor 2 because of misfire in the engine. At this moment, the pinion moving body 4 is still in inertia rotation. Therefore, the meshing of the pinion moving body 4 (the pinion gear 30) with the ring gear 29 is normally incapacitated. In this case, because the end side of the pinion gear 30 is in contact with the end side of the ring gear 29, the pinion moving body 4 cannot advance and tends to rotate with the output shaft. As a result, the upper protrusion 6a engaging the protrusions and recesses 31a is pulled by the rotation of the pinion moving body 4, radially flexing and gradually moving in the middle of the rotation, as shown in Fig. 4, to radially outside the pinion moving body 4 along the incline 7c formed in the slot 7b of the plate 7 (Fig. 4C and 4D), upon rotation of the pinion moving body 4 by the predetermined angle, disengaging from the protrusions and recesses 31a (Fig. 4E), and being held by the holding part 7d which follows the incline 7c (Fig. 4F). Although a returning force is produced when the upper protrusion 6a which has disengaged from the protrusions and recesses 31a is pulled to the rotational direction and undergoes elastic deformation, the upper protrusion 6a, once held by the holding part 7d of the plate 7, will not disengage therefrom to engage the protrusions and recesses 31a again, because, while the starter 1 is starting, attraction of the electromagnet switch 5 (force to attract the plunger 38) urges the rotation restricting member 6 downward in Fig. 1 via the bar 44. However, if the force to urge the rotation restricting member 6 downward is weak against the returning force, the upper protrusion 6a may possibly disengage from the holding part 7d and engages the protrusions and recesses 31a again. Hence, the biasing force sufficient to keep the upper protrusion 6a in the holding part 7d must be applied to the rotation restricting member 6. After the upper protrusion 6a is held in the holding part 7d of the plate 7, the key switch 36 is turned off to stop current supply to the attraction coil 37. The plunger attraction force of the electromagnet switch 5 disappears so that a load biasing the rotation restricting member 6 downward in Fig. 1 via the bar 44 no longer exists. As a result, a reaction of the spring 43 pushes back the rotation restricting member 6 upward in Fig. 1, the upper protrusion 6a leaving the holding part 7d of the plate 7 and returning to the stationary position (the position shown in Fig. 1) at which it is held prior to the start of the starter 1. According to this embodiment, even when the pinion moving body 4 rotates while the meshing of the pinion gear 30 with the ring gear 29 is in the state of incapacity, the upper protrusion 6a engaging the protrusions and recesses 31a of the flange 31 gradually moves radially in the course of the rotation to the radial outside of the pinion moving body 4 along the incline 7c set up on the slot 7b of the plate 7, and, upon rotation of the pinion moving body 4 by the predetermined angle, can disengage from the protrusions and recesses 31a. Since this makes it possible to avoid repetitions of engagement and disengagement between the upper protrusion 6a and the protrusions and recesses 31a, which occur when the upper protrusion 6a while being engaged with the protrusions and recesses 31a is pulled by the rotation of the pinion moving body 4, extreme deformation of the upper protrusion 6a and damage to the protrusions and recesses 31a can be prevented. It will also be appreciated that avoiding repetitions of engagement and disengagement therebetween will eliminate noise due to such repetitions. Additionally, since generation of friction heat due to repetitions of engagement and disengagement therebetween is eliminated, the flowing of oil out of the thrust bearing 33 mounted on the pinion moving body 4 can be avoided, thus preventing the thrust bearing life from degrading. (Second Embodiment) In this embodiment shown in Figs. 6 and 7, the upper protrusion 6a is made easy to pull out of the protrusions and recesses 31a when the pinion moving body 4 rotates the predetermined angle. A rounded chamfer R is formed on the corners of the rear engaging sides of the protrusions and recesses 31a to make it easy for the tip of the upper protrusion 6a to pull out of the protrusions and recesses 31a toward the rotational direction of the pinion moving body 4. Also, as shown in Fig. 8 and Fig. 9, a cylindrical projection 46 which holds the tip of the upper protrusion 6a which has disengaged from the protrusions and recesses 31a is provided on the rear end side of the washer 33. According to this embodiment, when the pinion moving body 4 rotates while the pinion gear 30 and the ring gear 29 are incapable of meshing with each other, the upper protrusion 6 engaging the protrusions and recesses 31a undergoes elastic deformation due to rotation of the pinion moving body 4 so that the length of engagement with the protrusions and recesses 31a gradually becomes short. Upon rotation of the pinion moving body 4 from the position of the upper protrusion 6a in engagement with the protrusions and recesses 31a to another position by the predetermined angle, because the corners of the engagement sides of the protrusions and 31a are chamfered, the upper protrusion 6a can easily disengage therefrom (Fig. 6). The upper protrusion 6a after having disengaged from the protrusions and recesses 31a has the tip thereof held by the projection 46 set up at the rear end side of the washer 33 as shown in Fig. 9, thereby preventing a fall radially into the inner side (downward in Fig. 9). Although there is no illustration, even if the corners of the engagement sides of the protrusions and recesses 31a should be in a C-chamfering shape, the same advantage will be provided. In this embodiment, too, upon rotation of the pinion moving body 4 from the position of the upper protrusion 6a engaged with the protrusions and recesses 31a to another position by the predetermined angle, the upper protrusion 6a can disengage from the protrusions and recesses 31a, hence the same advantages as the first embodiment can be obtained. (Third Embodiment) In the foregoing first and the second embodiments, the upper protrusion 6a of the rotation restricting member 6 rotates in engagement with the protrusions and recesses 31a of the flange 31 and comes in contact with the incline 7c of the plate 7 as shown in Fig. 10. Because the axial spacing between the ring gear 29 and the pinion moving body 4 varies from L1 to L2 from starter to starter (Fig. 11), the axial spacing or length in the axial direction from the engaging part 6A with the incline 7c to the engaging part 6B with the protrusions and recesses 31a of the flange 31 will vary from L11 to L12 (Fig. 12 and Fig. 13). At the engaging part 6A with the incline 7c of the upper protrusion 6a, a bending stress due to rotational force from the pinion moving body 4 occurs, but because such bending stress is prepartal to the foregoing lengths from L11 to L12 in the axial direction, when a variation of lengths in the axial direction occurs, there will also be a variation of bending stress. As a result, there is a need to design the strength of the rotation restricting member 6 by taking into account the maximum stress of variation. Accordingly, in the third embodiment, a pinion retreat restricting member 47 is additionally provided as shown in Fig. 14 so that it moves with the pinion moving body 4 to reduce the bending stress which exerts on the upper protrusion 6a. As shown in Figs. 15, 16A and 16B, the pinion retreat restricting member 47 comprises a fulcrum 47a serving as a rotational fulcrum and an annular part formed integrally with the fulcrum 47a. The fulcrum 47a is pivotally supported by a pin 49 fixed to the plate 48. The annular part is made up of a forked part 47b which forks and extends from the fulcrum 47a, a pair of side parts 47c extending upward from the forked part 47b, and a connecting part 47d which links the pair of the side parts 47c. On both shoulders of the connecting part 47d is formed a protuberant surface 47e as engagement part disengaging means. It is to be noted that when viewed from side as shown in Fig. 16A, each of the side parts 47c is formed approximately in the shape of "<", a bent part of which is engaged with engagement protrusions 33a provided on the washer 33 (thrust bearing) of the pinion moving body 4. The engagement protrusions 33a are set up on a pair of protrusions 33b which are protrudingly provided from both left and right ends of the washer 33 rearwardly (opposite side of the ring gear 29), each protruding radially to inside the core of the pinion moving body 4. When the pinion moving body 4 subjected to rotational restriction by engagement with the rotation restricting member 6 (upper protrusion 6a) advances on the output shaft 3, the side parts 47c is axially pulled while being engaged with the engagement protrusions 33a of the washer 33, so that the entire pinion retreat restricting member 47 rotates relative to the pin 49. Thereafter, when the pinion gear 30 of the pinion moving body 4 meshes with the ring gear 29 advancing the predetermined distance, the upper protrusion 6a of the rotation restricting member 6 disengages from the protrusions and recesses 31a formed on the flange 31 of the pinion moving body 4 and falls behind the pinion moving body 4, thereby releasing the rotation restriction on the pinion moving body 4. Further, the tip of the upper protrusion 6a comes into contact with the rear end side of the connecting part 47d of the pinion retreat restricting member 47, thereby restricting the retreat of the pinion moving body 4. On the other hand, in the event that the pinion moving body 4 rotation of which has been restricted advances on the output shaft 3 but the pinion gear 30 cannot mesh with the ring gear 29, the upper protrusion 6a of the rotation restricting member 6 while being engaged with the protrusions and recesses 31a of the flange 31 is pulled by the rotation of the pinion moving body 4 and rotates (flexes). Upon rotation of the pinion moving body 4 by the predetermined angle, the upper protrusion 6a comes into contact with the protuberant surface 47e provided on the pinion retreat restricting member 47 (Fig. 16), and can disengage from the protrusions and recesses 31a by further gradually moving radially outside the pinion moving body 4 along the protuberant surface 47e (Fig. 18). It is to be noted that when the upper protrusion 6a has come into contact with the protuberant surface 47e, bending stress upon the contact part with the protuberant surface 47e is prepartal to the length in the axial direction from the engaged part of the upper protrusion 6a with the protrusions and recesses 31a to the contact part. However, as shown in Fig. 14, since there exists variations of the axial spacing from L1 to L2 between the pinion moving body 4 and the ring gear 29, a variation from L13 to L14 occurs likewise in the length in the axial direction from the engaged part of the upper protrusion 6a with the protrusions and recesses 31a to the contact part (Fig. 19 and Fig. 20). It is to be noted, however, that since the pinion retreat restricting member 47 having engagement part disengaging means (protuberant surface 47e) can move with the pinion moving body 4 in this third embodiment, the axial spacing L13 and L14 become shorter than the axial lengths L11 and L12 in the first and the second embodiments and the variations thereof from L13 to L14 become smaller than the variations from L11 to L12 of the first and the second embodiments. As a result, as compared with the first and the second embodiments, the bending stress upon the upper protrusion 6a can be reduced. The foregoing embodiments are not restrictive but may be modified or altered in many other ways without departing from the scope of the invention as defined in the claims.

Claims: A starter comprising: a starting motor (2) for generating rotation force; an output shaft (3) for rotating as driven by the starting motor; a pinion moving body (4) fitted movably on the output shaft through helical splines (3a, 4a), the pinion moving body having a pinion gear on a front part thereof for meshing with a ring gear (29) of an engine and having protrusions and recesses (31a) on an entire periphery of a rear part thereof; a rotation restricting member (6) having an engagement part (6a) engageable with the protrusions and recesses to elastically restrict rotation of the pinion moving body while the engagement part is in engagement with the protrusions and recesses; moving means (5, 44) to move the engagement part of the rotation restricting member to the protrusions and recesses, characterized by disengaging means (7, 47, 48) to disengage the engagement part from the protrusions and recesses upon rotation of the pinion moving body by a predetermined angle with the engagement part being in engagement therewith. A starter as claimed in claim 1, wherein: the disengaging means has a guide surface (7c, 47c) guiding the engagement part radially from the protrusions and recesses to an outside with rotation of the pinion moving body. A starter as claimed in claim 1, wherein: the protrusions and recesses have chamfers formed at least on rotational direction sides of the pinion moving body at the rear end. A starter as claimed in any one of claims 1 to 3, wherein: the disengaging means is coupled with the pinion moving body to move therewith. A starter as claimed in any one of claims 1 to 4, further comprising: retreat restricting means (47) to restrict retreat of the pinion moving body after advancing a predetermined distance toward the ring gear, the retreat restricting means providing the disengaging means integrally therewith.

Inventors: ARAKI TAKESHI, MATSUSHIMA KEIICHI, SOH MASAHIRO, ARAKI, TAKESHI, MATSUSHIMA, KEIICHI, SOH, MASAHIRO
Applicants: DENSO CORP, DENSO CORPORATION
Application year: 1997
Main classification: F02N15
IPC codes: F02N15