Starter with pinion return preventing mechanism

Abstract: Rotation of a pinion (200) is regulated by a return/rotation regulating claw (231) when a starter (500) is actuated. After the pinion (200) engages the ring gear (100), the return/rotation regulating claw (231) positioned rearward the pinion (200) regulates the return of the pinion (200) from the ring gear (100). A thrust bearing (215) including a rolling bearing positioned on the rear face of the pinion (200) absorbs the difference between the rotational speed of the pinion (200) and that of the return/rotation regulating claw (231). Such a construction allows only the pinion (200) to move axially and a magnet switch (600) to be compact and light.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention: The present invention relates to a starter for starting an engine by engaging a pinion with a ring gear of an engine and driving the pinion, and more particularly to a starter having a pinion return preventing mechanism according to the preamble of claim 1. 2. Related Art: As a moving member for moving a pinion of a starter axially, the conventional art disclosed in Laid-Open Japanese Utility Model Publication No. (JP-U) 1-131872 is known. In the starter disclosed in this publication, a pinion shaft and a one-way clutch are axially movably provided relatively to each other, and the pinion shaft is driven to shift the pinion shaft and the pinion, unlike the starter in which the pinion, the pinion shaft (output shaft), and the one-way clutch are shifted integrally. The construction disclosed in this publication allows the weight to be shifted to be smaller and a magnet switch to be compact. The weight of the pinion shaft is, however, about five times as great as that of the pinion. Therefore, there is a demand for the improved starter capable of shifting only the pinion to reduce energy required to shift it. Document US 1,527,588 discloses a starter having a motor and a pinion for engagement with a ring gear. In this arrangement, the pinion is allowed to disengage from the ring gear and to return towards the motor. Thus, according to the aspects discussed above, the pinion can get out of engagement from the ring gear during engine starting operation. From US 1,330,326, a further starter arrangement is known. It comprises a pinion engageable with a ring gear of an engine, an output shaft having a helical spline thereon, a starter motor for generating a rotational force to be transmitted to the pinion and a spring which acts to move the pinion to a ring gear side. Further, this document shows a bearing which reduces frictional resistance when moving the pinion to the ring gear side. When the pinion is engaged with the ring gear, the pinion is separated from said bearing, as the movement of the bearing to the ring gear side is restricted by interlocking of a shell and a collar. There is no shift-maintaining member in order to keep the engagement of the pinion and the ring gear. Document US-A-2,332,986 dicloses a starter according to the preamble of claim 1. It comprises an output shaft having an having a helical spline thereon, a pinion moving member having a pinion engagable with a ring gear of an engine and mounted axially movable through an engagement with helical spline of the output shaft. The starter further comprises a motor for driving the output shaft wherein the motor moving the pinion to a ring gear side by a difference of rotational speed relative to the pinion moving member to engage the pinion with the ring gear. Further, the starter comprises a return regulating means for preventing and regulating a return of the pinion from the ring gear when the pinion has engaged the ring gear through the pinion moving member. However, this arrangement does not solve the problem of frictional wear between the return regulating means and the pinion. Thus, it is necessary to provide a technique for preventing the shift-maintaining member and the pinion from being worn, as well as a technique for reducing rotational loss between the shift-maintaining member and the pinion from being generated. SUMMARY OF THE INVENTION The present invention has been made in view of the above described drawbacks and has a first object of providing an improved starter. The present invention has a second object of providing a starter capable of reducing to a less amount the degree of wear and rotational loss between a pinion and a member for keeping the state in which the pinion is in mesh with a ring gear. The present invention has a third object of providing a starter capable of reducing energy required to shift a pinion by shifting a pinion in the axial direction of an output shaft for driving the pinion. These objects will be solved by the features of claim 1. According to the present invention, a return regulating member is provided at one side of a pinion in the axial direction thereof through a bearing, for regulating the return of the pinion in the axial direction thereof after engagement with a ring gear. Thus, the pinion does not disengage from the ring gear and the rotational torque of the motor is transmitted to the engine through the ring gear. Further, an absorbing member excluding a sliding-type bearing such as a thrust bearing is provided between the pinion and the return regulating member to absorb the difference in the rotational speeds of the pinion and the return regulating member. Thus, generation of wear, heat, and the loss of the rotational torque between the pinion and the return regulating member can be suppressed, thus maintaining the performance of the starter for a long time. Preferably, a rotation restricting member is provided for regulating the rotation of the pinion to move the pinion axially for engagement with the ring gear. The rotation restricting member is manufactured integrally with the return regulating member to act as the return regulating member as well. Thus, the starter has a simple construction and hence, can be made light in weight and compact in size. More preferably, the pinion includes a pinion inner member having a helical inner spline and a pinion outer member having a pinion gear, and those members are produced separately. Thus, the helical inner spline (inner teeth) and the pinion gear (outer teeth) can be manufactured by the most appropriate method, respectively. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a sectional side view showing an embodiment of a starter according to the present invention (first embodiment); Figs. 2A and 2B are a front view and a partial sectional side view of a rotation regulating member fitted on a pinion part (first embodiment); Fig. 3 is a perspective view showing the rotation regulating member (first embodiment); Fig. 4 is a rear view of a center bracket (first embodiment); Fig. 5 is a sectional side view of the center bracket (first embodiment); Fig. 6 is a front view of the center bracket (first embodiment); Fig. 7 is a sectional side view of an armature (first embodiment); Fig. 8 is a front view of a yoke (first embodiment); Fig. 9 is an exploded perspective view of a plunger and fixed contacts of a magnet switch (first embodiment); Fig. 10 is a perspective view showing the magnet switch (first embodiment); Fig. 11 is a sectional side view showing an end frame and compression coil springs (first embodiment); Fig. 12 is a rear view showing a brush holder (first embodiment); Fig. 13 is a sectional side view taken along a line XIII-XIII in Fig. 12 (first embodiment); Fig. 14 is a sectional side view taken along a line XIV-XIV in Fig. 12 (first embodiment); Figs. 15A, 15B, and 15C are electric circuit diagrams showing the operation state of the pinion (first embodiment); Fig. 16 is a sectional view showing a starter (second embodiment); Fig. 17 is a sectional view showing a pinion (third embodiment); Fig. 18 is a side elevational view showing a rotation regulating member and a return regulating member (fourth embodiment); Fig. 19 is a front view of the members shown in Fig. 18 (fourth embodiment); Fig. 20 is an exploded perspective view of Fig. 18 (fourth embodiment); and Fig. 21 is an explanatory view of the operation of a return regulating member (fourth embodiment). DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS Next, the starter according to this invention will be described based on embodiments shown in the accompanying drawings. [First Embodiment] Figs. 1 through 15A-15C show a first embodiment, with Fig. 1 being an entire sectional view of a starter. The starter can be generally divided into a housing 400 containing a pinion 200 which meshes with a ring gear 100 mounted on an engine and a planetary gear speed reduction mechanism 300, a motor 500, and an end frame 700 containing a magnet switch 600. Inside the starter, the housing 400 and the motor 500 are separated by a motor spacer wall 800, and the motor 500 and the end frame 700 are separated by a brush holding member 900. (Pinion 200) As shown in Fig. 1 and Figs. 2A-2B, a pinion gear 210 which meshes with the ring gear 100 of the engine is formed on the outer periphery of a pinion 200. A helical inner spline 211 which mates with a helical outer spline 221 formed on the outer periphery of an output shaft 220 is formed. Thus, the pinion 200 is spline-engaged on the output shaft 220 to be axially movable on the output shaft 220. The pinion 200 is so arranged to advance toward the ring gear 100 due to the difference in rotational speeds when the output shaft 220 rotates at higher speed than the pinion 200. A tapered portion 222 is formed on the rear end of the output shaft 220 so that the helical inner spline 211 of the pinion 200 abuts the tapered portion 222 to stop a rearward movement of the pinion 200 further from the tapered portion 222. A pinion stopping ring 250 is mounted on the front side of the output shaft 220 to stop a forward movement of the pinion 200 further from the pinion stopping ring 250. On the opposite side of the pinion 200 from the ring gear 100, a flange 213 of greater diameter than the external diameter dimension of the pinion gear 210 is formed in circular disk form. A number of convexes/concaves 214 greater than the number of outer teeth of the pinion gear 210 are formed around the entire outer circumference of this flange 213. These convexes/concaves 214 are for a return/rotation regulating claw 231 of a rotation regulating member 230 which will be discussed later to mate with. A thrust bearing 215 (absorbing means) is mounted on the rear end of the flange 213 to absorb the difference in rotational speeds of the pinion 200 and the return/rotation regulating claw 231. According to the embodiment, a bearing which bears axially applied load is called as a thrust bearing. The thrust bearing 215 in this embodiment uses a rolling bearing and is comprised of an orbital ring 216 which is to be abutted by the front end of the return/rotation regulating claw 231 and a plurality of balls 217 rotatable between the orbital ring 216 and the rear face of the flange 213. By the rotation of the balls 217, the rotational difference between the pinion 200 and the return/rotation regulating claw 213 is absorbed. The balls 217 may be made of steel but preferably made of ceramics to improve durability. The thrust bearing 215 is mounted in a recess 218 formed on the rear face of the flange 213, and then an annular portion 219 formed on the rear end of the pinion 200 is bent outwardly so that it is kept rotatably on the rear face of the flange 213 and unable to come off in the axial direction. By the rotatable thrust bearing 215 being mounted on the rear face of the flange 213 of the pinion 200 in this way, when the rotation regulating member 230 which will be discussed later drops in behind the pinion 200, the front end of the return/rotation regulating claw 231 abuts the orbital ring 216 of the thrust bearing 215. As a result, the rotation of the pinion 200 is absorbed by the thrust bearing 215 and the rotation torque of the pinion 200 is not transmitted to the return/rotation regulating claw 231. Thus, this prevents generation of wear, heat and rotation loss between the pinion 200 and the return/rotation regulating claw 231. Further, when the pinion 200 is driven by the ring gear 100 and rotated at a higher speed than the output shaft 220 to cause a speed difference by which a force is applied to return the pinion 200 rearward, a large load is applied between the pinion 200 and the return/rotation regulating claw 231. Since this rotational difference is absorbed by the thrust bearing 215, wear, heat generation and rotational loss between the pinion 200 and the return/rotation regulating claw 231 can be reduced. The pinion 200 is urged toward the rear of the output shaft 220 at all times by a return spring 240 made of a compression coil spring. The return spring 240 does not urge the pinion 200 directly but in this embodiment urges the pinion 200 by way of a ring body 421 of a shutter 420 which opens and closes an opening portion 410 of the housing 400 discussed later. (Rotation Regulating Member 230) The rotation regulating member 230 constituting pinion moving means, as shown in Fig. 3, is a sheet spring member wound through approximately 3/2 turns of which approximately 3/4 turn is a rotation regulating portion 232 of long axial sheet length and high spring constant and the remaining approximately 3/4 turn is a return spring portion 233 constituting urging means of short axial sheet length and low spring constant. The return/rotation regulating claw 231 which constitutes a regulating portion extending in the axial direction and which mates with the multiple convexes/concaves 214 formed in the flange 213 of the pinion 200 is formed at one end of a regulating portion 232. This return/rotation regulating claw 231 performs two functions as rotation regulating means and return regulating means; the rotation regulating means stops rotation of the pinion 200 along the predetermined axial length at the time of start of rotation of the motor 500 to cause rotational difference between the output shaft 220 and the pinion 200 and move the pinion 200 axially, and the return regulating means drops into the axial rear end side to stop a return of the pinion 200 in a state of engagement of the pinion 200 with the ring gear 100 after the axial advance of the pinion 200 by the predetermined length. This return/rotation regulating claw 231, as well as mating with the convexes/concaves 214 of the pinion 200, in order to increase the rigidity of the return/rotation regulating claw 231, is formed axially long and is bent radially inward into a cross-sectional L-shape. (It is bar-like.) The regulating portion 232 which supports the return/rotation regulating claw 231 elastically deformably is provided with a straight portion 235 which extends vertically. This straight portion 235 is vertically slidably supported by two supporting arms 361 mounted projecting from the front face of a center bracket 360. That is, the straight portion 235 moving vertically causes the regulating portion 232 to move vertically also. Also, a sphere 601 of the front end of a cord-shaped member 680 (for example, a wire), which will be further discussed later, for transmitting the movement of the magnet switch 600, which will be further discussed later, is in engagement with the position 180° opposite the return/rotation regulating claw 231 of the regulating portion 232. The end portion side of the return spring portion 233 has a large curvature of winding and one end portion 236 of the return spring portion 233 abuts the upper face of a regulating shelf 362 mounted projecting from a front face of a lower portion of the center bracket 360. The operation of the rotation regulating member 230 will now be explained. The cord-shaped member 680 is transmitting means for transmitting the movement of the magnet switch 600 to the regulating portion 232, and the movement of the magnet switch 600 pulls the regulating portion 232 downward and causes the return/rotation regulating claw 231 to engage with the convexes/concaves 214 on the flange 213 of the pinion 200. At that time, because the end portion 236 of the return spring portion 233 is in abutment with the regulating shelf 362 for position regulating, the return spring portion 233 bends. Because the regulating claw 231 is in engagement with the convexes/concaves 214 on the pinion 200, when the output shaft 220 starts to be rotated by way of the armature shaft 510 of the motor 500 and the planetary gear speed reduction mechanism 300, rotational speed difference is caused between the pinion 200 and the output shaft 220 and the pinion 200 advances along the helical outer spline 221 on the output shaft 220. When the pinion 200 advances, abuts the ring gear 100 and the advance of the pinion 200 is obstructed, further rotational force of the output shaft 210 causes the rotation regulating member 230 itself to bend and the pinion 200 rotates slightly and meshes with the ring gear 100. When the pinion 200 advances further under this engagement, the return/rotation regulating claw 231 disengages from the convexes/concaves 214, the return regulating claw 231 drops in behind the flange 213 of the pinion 200, the front end of the return/rotation regulating claw 231 abuts the rear face of the thrust bearing 215 and prevents the pinion 200 from retreating under the rotation of the ring gear 100 of the engine. As the operation of the magnet switch 600 stops and the cord-shaped member 680 stops pulling the regulating portion 232 downward, the action of the return spring portion 233 causes the regulating portion 232 to return to its original position. (Pinion Stopping Ring 250) The pinion stopping ring 250 is fixed in a circular groove of rectangular cross-section formed around the output shaft 220. This pinion stopping ring 250 is a piece of steel of rectangular cross-section processed into a circular shape; a substantially S-shaped corrugation 251 (an example of engaging means) is formed at each end, and the convex portion of one is in engagement with the concave portion of the other and the convex portion of the other is in engagement with the concave portion of the first. (Planetary Gear Speed Reduction Mechanism 300) The planetary gear speed reduction mechanism 300, as shown in Fig. 1, is speed reducing means for reducing the rotational speed of the motor 500, which will be further discussed later, and increasing the output torque of the motor 500. The planetary gear speed reduction mechanism 300 is made up of a sun gear 310 formed on the front-side outer periphery of the armature shaft 510 (discussed later) of the motor 500, a plurality of planetary gears 320 which mesh with this sun gear 310 and rotate around the circumference of the sun gear 310, a planet carrier 330 which rotatably supports these planetary gears 320 around the sun gear 310 and is formed integrally with the output shaft 220, and an internal gear 340 which is of a cylindrical shape meshing with the planetary gears 320 at the outer periphery of the planetary gears 320 and is made of resin. (Overrunning Clutch 350) The overrunning clutch 350 supports the internal gear 340 rotatably in one direction only (only the direction in which it rotates under the rotation of the engine). The overrunning clutch 350 has a clutch outer 351 constituting a first cylindrical portion integrally formed in the front side of the internal gear 340, a circular clutch inner 352 constituting a second cylindrical portion formed in the rear face of the center bracket 360 constituting a fixed side covering the front of the planetary gear speed reduction mechanism 300 and disposed facing the clutch outer 351, and rollers 353 accommodated in a roller housing portion 351a formed inclined to the inner face of the clutch outer 351. (Center Bracket 360) The center bracket 360 is shown in Fig. 4 through Fig. 6 and is disposed inside the rear end of the housing 400. The housing 400 and the center bracket 360 are linked by a ring spring 390 having one end engaged with the housing 400 and the other end engaged with the center bracket 360 and are arranged in such a way that the rotational reaction received by a clutch inner 352 constituting the overrunning clutch 350 is absorbed by the ring spring 390 and the reaction is not directly transmitted to the housing 400. Also, two supporting arms 361 which hold the rotation regulating member 230 and the regulating shelf 362 on which the lower end of the rotation regulating member 230 is loaded are mounted on the front face of the center bracket 360. Further, a plurality of cutout portions 363 which mate with convex portions (not shown in the figure) on the inner side of the housing 400 are formed around the center bracket 360. The upper side cutout portions 363 are used also as air passages for guiding air from inside the housing 400 into a yoke 501 (this is discussed in detail later in connection with the cooling air passage). Also, a concave portion 364 through which the cord-shaped member 680 (discussed later) passes in the axial direction is formed at the lower end of the center bracket 360. (Planet Carrier 330) The planet carrier 330 is provided at its rear end with a flange-like projecting portion 331 which extends radially in order to support the planetary gears 320. Pins 332 extending rearward are fixed to this flange-like projecting portion 331, and these pins 332 rotatably support the planetary gears 320 by way of metal bearings. The planet carrier 330 has its front end rotatably supported by a housing bearing 440 fixed inside the front end of the housing 400 and a center bracket bearing 370 fixed inside an inner cylindrical portion 365 of the center bracket 360. The planet carrier 330 has an annular groove 334 at a front position of an inner cylindrical portion and a stopper ring 335 is fitted into the annular groove 334. Between the stopper ring 335 and the front end of the inner cylindrical portion 365, a washer 336 is disposed rotatably against the planet carrier 330. The stopper ring 335, abutting the front end of the inner cylindrical portion 365 through the washer 336, stops rearward movement of the planet carrier 330. The rear end of the center bracket bearing 370 supporting the rear side of the planet carrier 330 has a flange portion 371 which is sandwiched between the rear end of the inner cylindrical portion 365 and a flange-shaped protruding portion 331. The flange-shaped protruding portion 331, abutting the rear end of the inner cylindrical portion 365 through a flange portion 371, restricts forward movement of the planet carrier 330. On the rear face of the planet carrier 330, a concave portion 337 extending axially is formed so that the front end of the armature shaft 510 is rotatably supported through a planet carrier bearing 380 disposed in the concave portion 337. (Housing 400) The housing 400 supports the output shaft 220 with the housing bearing 440 fixed in the front end of the housing 400 and also is provided with a water barrier wall 460 which in order to minimize the incursion of rainwater and the like through the opening portion 410 minimizes the gap at the lower part of the opening portion 410 between the outer diameter of the pinion 200 and the housing 400. Also, two slide grooves 450 extending axially are provided at the lower part of the front end of the housing 400, and a shutter 420 which will be further discussed later is disposed in these slide grooves 450. (Shutter 420) The shutter 420 is made of a resinous member (for example nylon), is mounted on the output shaft 220 and comprises a ring body 421 sandwiched between the return spring 240 and the pinion 200 and a water-barrier portion 422 which opens and closes an opening portion 410 in the housing 400. A washer 480 is interposed between the ring body 421 and the pinion 200. The operation of the shutter 420 is such that when the starter starts to operate and the pinion 200 shifts forward along the output shaft 220 the ring body 421 shifts forward together with the pinion 200. When this happens, the water-barrier portion 422 integral with the ring body 421 shifts forward and opens the opening portion 410 of the housing 400. When the starter stops operating and the pinion 200 shifts backward along the output shaft 220, the ring body 421 also shifts backward together with the pinion 200. When this happens, the water-barrier portion 422 integral with the ring body 421 also shifts backward and closes the opening portion 410 of the housing 400. As a result, the shutter 420, which constitutes opening and closing means, by means of the water-barrier portion 422 prevents rainwater and the like which is splashed by the centrifugal force of the ring gear 100 from getting inside the housing 400 when the starter is not operating. A seal member 430 is disposed in the inner front end of the housing 400 to prevent the rainwater or dust which enters through the opening 410 of the housing 400 from entering further into the housing bearing 440 at the front end of the housing 400. A housing top seal member 470 is attached on the outer front end of the housing 400 to prevent the rainwater or dust from entering from outside into the housing bearing 440. (Motor 500) The motor 500 is enclosed by a yoke 501, a motor spacer wall 800, and a brush holding member 900 which will be discussed later. The motor spacer wall 800 houses the planetary gear speed reduction mechanism 300 between itself and the center bracket 360, and also fulfills the role of preventing lubricating oil inside the planetary gear speed reduction mechanism 300 from getting into the motor 500. The motor 500, as shown in Fig. 1, is made up of an armature 540 comprising the armature shaft 510 and an armature core 520 and armature coils 530 which are mounted on and rotate integrally with this armature shaft 510, and fixed poles 550 which rotate the armature 540, and the fixed poles 550 are mounted around the inside of the yoke 501. (Armature Shaft 510) The armature shaft 510 is rotatably supported by the planet carrier bearing 380 provided at inside rear portion of the planet carrier 330 and a brush holder bearing 564 fixed on the inner periphery of the brush holder 900. (Armature Core 520) The armature core 520 is, as shown in Fig. 7, made of a plurality of core plates 521 stacked together and the armature shaft 510 is press-fitted into a central hole of the core 520. Each core plate 521 is made by press-punching a thin steel plate and coated with an insulating material on its face. A plurality of slots (for example, 25) 524 are formed on the outer periphery of the core plate 521 to receive therein armature coils 530. (Armature Coils 530) For the armature coils 530, in this embodiment multiple (for example 25) upper layer coil bars 531 and the same number of lower layer coil bars 532 as these upper layer coil bars 531 are used, and 2-layer-winding coils wherein the respective upper layer coil bars 531 and the lower layer coil bars 532 are stacked in the radial direction are employed. The upper layer coil bars 531 and lower layer coil bars 532 are paired, and the ends of the upper layer coil bars 531 and the ends of the lower layer coil bars 532 are electrically connected to constitute ring-shaped coils. (Upper Layer Coil Bars 531) The upper layer coil bars 531, as shown in Fig. 7, are made of a material having excellent electrical conductivity (for example, copper), and are each provided with an upper layer coil arm 533 which extends in parallel with the fixed poles 550 and is held in the outer sides of slots 524 and 2 upper layer coil ends 534 which are bent inward from both ends of the upper layer coil arm 533 and extend in a direction orthogonal to the axial direction of the armature shaft 510. The upper layer coil arm 533 and the 2 upper layer coil ends 534 may be a member integrally molded by cold casting, may be a member shaped by bending in a press into a U-shape, or may be a member formed by joining a upper layer coil arm 533 and 2 upper layer coil ends 534 made as separate parts by a joining method such as welding. (Lower Layer Coil Bars 532) The lower coil bars 532, like the upper coil bars 531, are made from a material having excellent electrical conductivity (for example copper), and each comprise a lower layer coil arm 536 which extends parallel with respect to the fixed poles 550 and is held in the inner sides of slots 524 and 2 lower layer coil ends 537 which are bent inward from the ends of this lower layer coil arm 536 and extend orthogonal to the axial direction of the armature shaft 510. The lower layer coil arm 536 and the 2 lower layer coil ends 537, like the upper layer coil bar 531, may be a member integrally molded by cold casting, may be a member shaped by bending in a press into a U-shape, or may be a member formed by joining a lower layer coil arm 536 and 2 lower layer coil ends 537 made as separate parts by a joining method such as welding. Insulation between the upper layer coil ends 534 and the lower layer coil ends 537 is secured by insulating spacers 560, and insulation between the lower layer coil ends 537 and the armature core 520 is secured by an insulating ring 590 made of resin (for example, nylon or phenol resin). The upper coil arms 533 and the lower coil arms 536 are each coated with an insulating film (not shown) to be insulated from the armature core 520 and insulated from each other. Of the two upper coil ends 534, the upper coil ends 534 disposed at the side of the magnet switch 600 directly abuts a brush 910 described later to supply power to the armature coil 530. Therefore, at least the surface of the upper coil end 534 the which abuts the brush 910 is smoothed. An end portion 538 of the upper coil ends 534 and end portion 539 of the lower coil ends 537 are coupled through an insulating cap 580 to a metal collar 570 press-fitted onto the armature shaft 510. Thus, the upper coil end 534 and the lower coil end 537 are prevented from expanding in the axial direction, and the inner diameter of the armature coils 530 are prevented from expanding by the centrifugal force. The collar 570 disposed at the front side abuts the rear face of motor separating wall 800 positioned in front thereof and operates as a thrust receiving portion which restricts the forward movement of the armature 540. On the other hand, the collar 570 disposed behind the starter abuts the front face of the brush holder member 90 positioned therebehind and operates as thrust receiving portion which restricts thr rearward movement of the armature 540. (Yoke 501) The yoke 501, as shown in Fig. 8, is a cylindrical body formed by rolling a steel plate, and around it are formed a plurality of concave grooves 502 extending axially and sunk toward the inner circumference. These concave grooves 502 are used for, as well as disposing through bolts, positioning fixed poles 550 on the inner circumference of the yoke 501. (Fixed Poles 550) In this embodiment permanent magnets are used for the fixed poles 550 and, as shown in Fig. 8, they comprise a plurality of (for example 6) main poles 551 and inter-pole poles 552 disposed between these main poles 551. Field coils which generate magnetic force by electrical current flow may be used instead of permanent magnets for the fixed poles 550. The main poles 551 are positioned by the ends of the inner sides of channel grooves 502 in the above-mentioned yoke 501, and are fixed in the yoke 501 by fixing sleeves 553 disposed around the inside of the fixed poles 550 with the inter-pole poles 552 disposed between the main poles 551. (Magnet Switch 600) The magnet switch 600, as shown in Fig. 1, Fig. 9 and Fig. 10, is held in a brush holder 900 which will be discussed later, is disposed inside an end frame 700 which will be discussed later, and is fixed so as to be substantially orthogonal to the armature shaft 510. In the magnet switch 600, as shown in Figs. 9 and 10, electrical current drives a plunger 610 upward, and 2 contacts (a lower movable contact 611 and an upper movable contact 612) which move together with the plunger 610 are sequentially caused to abut with the head portion 621 of a terminal bolt 620 and an abutting portion 631 of a fixed contact 630. A battery cable not shown in the figures is connected to the terminal bolt 620. The magnet switch 600 is structured inside a magnet switch cover 640 which is cylindrical and has a bottom and is made from magnetic parts (for example, made of iron). The magnet switch cover 640 is for example a pliable steel plate press-formed into a cup shape, and in the center of the bottom of the magnet switch cover 640 there is a hole 641 through which the plunger 610 passes movably in the vertical direction. Also, the upper opening of the magnet switch cover 640 is closed off by a stationary core 642 made of a magnetic body (for example, made of iron). The stationary core 642 consists of an upper large diameter portion 643, a lower middle diameter portion 644, and a still lower small diameter portion 645, and the stationary core 642 is fixed in the upper opening of the magnet switch cover 640 by the outer periphery of the large diameter portion 643 being caulked to the inner side of the upper end of the magnet switch cover 640. The upper end of an attracting coil 650 is fitted around the middle diameter portion 644. The upper end of a compression coil spring 660 which urges the plunger 610 downward is fitted around the periphery of the small diameter portion 645 of the stationary core 642. The attracting coil 650 is attracting means which generates magnetism when a current flows through it and attracts the plunger 610, and the attracting coil 650 is provided with a sleeve 651 which has its upper end fitted to the middle diameter portion 644 of the stationary core 642 and covers the plunger 610 slidably in the vertical direction. This sleeve 651 is made by rolling up a non-magnetic thin plate (for example, copper plate, brass, stainless steel), and insulating washers 652 made of resin or the like are provided at the upper and lower ends of this sleeve 651. Around the sleeve 651 between these two insulating washers 652 there is wound a thin insulating film (not shown in the drawings) made of resin (for example cellophane, nylon film) or paper, and around that insulating film is wound a predetermined number of turns of a thin enamel wire, whereby the attracting coil 650 is constituted. The plunger 610 is made of a magnetic metal (for example, iron) and has a substantially cylindrical shape comprising an upper small diameter portion 613 and a lower large diameter portion 614. The lower end of the compression coil spring 660 is fitted to the small diameter portion 613, and the large diameter portion 614, which is relatively long in the axial direction, is held slidably vertically in the sleeve 651. A plunger shaft 615 extending upward from the plunger 610 is fixed to the upper end of the plunger 610. This plunger shaft 615 projects upward through a through hole provided in the stationary core 642. An upper movable contact 612 is fitted around the plunger shaft 615 above the stationary core 642 slidably vertically along the plunger shaft 615. This upper movable contact 612, as shown in Fig. 9, is limited by a stopping ring 616 fitted to the upper end of the plunger shaft 615 so that it does not move upward of the upper end of the plunger shaft 615. As a result, the upper movable contact 612 is vertically slidable along the plunger shaft 615 between the stopping ring 616 and the stationary core 642. The upper movable contact 612 is urged upward at all times by a contact pressure spring 670 consisting of a sheet plate spring fitted to the plunger shaft 615. The upper movable contact 612 is made of a metal such as copper having excellent conductivity, and when both ends of the upper movable contact 612 move upward they abut with the 2 abutting portions 631 of the fixed contact 630. The lead wires 910a of a pair of brushes 910 are electrically and mechanically fixed to the upper movable contact 612 by caulking or welding or the like. Also, the end portion of a resistor member 617 constituting a plurality of (in this embodiment, 2) limiting means is inserted and electrically and mechanically fixed in a groove portion of the upper movable contact 612. The lead wires 910a are electrically and mechanically fixed to the upper movable contact 612 by caulking or welding, but the upper movable contact 612 and the lead wires 910a of the brushes 910 may alternatively be formed integrally. The resistor member 617 is for rotating the motor 500 at low speed when the starter starts to operate, and consists of a metal wire of high resistance wound through several turns. A lower movable contact 611 located below the head portion 621 of the terminal bolt 620 is fixed by caulking or the like to the other end of the resistor member 617. The lower movable contact 611 is made of a metal such as copper having excellent conductivity, and when the magnet switch 600 stops and the plunger 610 is in its downward position abuts the upper face of the stationary core 642, when the resistor member 617 moves upward along with the movement of the plunger shaft 615, before the upper movable contact 612 abuts the abutting portion 631 of the fixed contact 630 it abuts the head portion 621 of the terminal bolt 620. The lower face of the plunger 610 is provided with a recess portion 682 which accommodates a sphere 681 provided at the rear end of the cord-shaped member 680 (for example, a wire). A female thread 683 is formed on the inner wall of this female thread 683. A fixing screw 684 which fixes the sphere 681 in the recess portion 682 is screwed into this recess portion 682. This fixing screw 684 is also used to perform adjustment of the length of the cord-shaped member 680, by adjusting the extent to which the fixing screw 684 is screwed into the female thread 683. The length of the cord-shaped member 680 is adjusted so that when the plunger shaft 615 moves upward and the lower movable contact 611 abuts the terminal bolt 620 the return/rotation regulating claw 231 of the regulating portion 232 mates with the convexes/concaves 214 of the outer periphery of the pinion 200. The female thread 683 and the fixing screw 684 constitute an adjusting mechanism. (End Frame 700) The end frame 700, as shown in Fig. 11, is a magnet switch cover made of resin (for example phenol resin), and accommodates the magnet switch 600. Spring holding pillars 710 which hold compression coil springs 914 which urge the brushes 910 forward are mounted projecting from the rear face of the end frame 700 in correspondence with the positions of the brushes 910. Also, the compression coil springs 914, as shown in Fig. 1, are disposed radially outward with respect to the axial direction of the plunger 610 of the magnet switch 600. The compression coil spring 914 can be used to the extent that its spring length becomes the radial length of the magnet switch 600. For this reason, the spring stress and load of the the compression coil spring 914 can be set to appropriate values with ease, resulting in prolonged life of the compression coil spring 914. The terminal bolt 620 is a steel bolt which passes through the end frame 700 from the inside and projects from the rear of the end frame 700 and has at its front end a head portion 621 which abuts the inner face of the end frame 700. The terminal bolt 620 is fixed to the end frame 700 by a caulking washer 622 being attached to the terminal bolt 620 projecting rearward of the end frame 700. A copper fixed contact 630 is fixed to the front end of the terminal bolt 620 by caulking. The fixed contact 630 has one or a plurality of (in this embodiment, 2) abutting portions 631 positioned at the top end of the inside of the end frame 700, and these abutting portions 631 are mounted so that the upper face of the upper movable contact 612 which is moved up and down by the operation of the magnet switch 600 can abut with the lower faces of the abutting portions 631. (Brush Holder 900) The brush holder 900, as well as the roles of separating the inside of the yoke 501 and the inside of the end frame 700 and rotatably supporting the rear end of the armature shaft 510 by way of the brush holder bearing 564, also fulfills the role of a brush holder, the role of holding the magnet switch 600, and the role of holding a pulley 690 which guides the cord-shaped member 680. The brush holder 900 has a hole portion not shown in the drawings through which the cord-shaped member 680 passes. The brush holder 900 is a spacing wall made of a metal such as aluminum molded by a casting method and, as shown in Fig. 12 through Fig. 14, has a plurality of (in this embodiment, 2 upper and 2 lower) brush holding holes 911, 912 which hold the brushes 910 in the axial direction. The upper brush holding holes 911 are holes which hold brushes 910 which receive a plus voltage, and these upper brush holding holes 911 hold the brushes 910 by way of resin (for example nylon, phenol resin) insulating cylinders 913 (Fig. 13 is a cross-section taken along A-A of Fig. 12, and Fig. 14 is a cross-section taken along B-B of Fig. 12). The lower brush holding holes 912 are holes which hold brushes 910 connected to earth, and these lower brush holding holes 912 hold the respective brushes 910 directly therein. In this way, by holding the brushes 910 by means of the brush holder 900, there is no need to provide the starter with independent brush holders. As a result, the number of parts in the starter can be reduced and assembly man-hours can be reduced. The brushes 910 are urged against the upper layer coil ends 534 at the rear ends of the armature coils 530 by the compression coil springs 914. The lead wires 910a of the upper brushes 910 are electrically and mechanically joined by a joining method such as welding or caulking to the upper movable contact 612 which is moved by the magnet switch 600. The lead wires 910a of the lower brushes 910 are caulked and thereby electrically and mechanically joined to a concave portion 920 formed in the rear face of the brush holder 900. Two seats 930 with which the front side of the magnet switch 600 abuts and two fixing pillars 940 which hold the periphery of the magnet switch 600 are formed on the rear side of the brush holder 900. The seats 930 are shaped to match the external shape of the magnet switch 600 in order to abut with the magnet switch 600, which has a cylindrical exterior. The two fixing pillars 940, with the magnet switch 600 in abutment with the seats 930, by having their rear ends caulked to the inner side, hold the magnet switch 600. A pulley holding portion 950 which holds a pulley 690 which converts the direction of movement of the cord-shaped member 680 from the vertical direction of the magnet switch 600 into the axial direction thereof is formed on the lower side of the rear side of the brush holder 900. On the rear face of the brush holding member 900, a holding portion 960 is provided for holding an over-temperature protecting temperature switch (not shown). The temperature switch turns off the magnet switch 600 at a predetermined temperature and stops motor operation, thereby protecting the starter. In the starter, air passages are formed for discharging the air outside in the manner that the centrifugal air flow is generated by the rotation of upper coil ends 534 positioned on the rear side of the armature coil 530, the air sucked through the housing is taken into the end frame 700 through an opening (indicated by numeral 980) of the brush holding member 900, thereafter the air is led to the rear side of the armature coil 530 through an opening (indicated by numeral 970) of the brush holding member 900 to cool the sliding surface of the brushes and peripheries, and finally the air is discharged with brush powders generated on the sliding surfaces through a dischage hole 503 formed on the bottom of the yoke 501. (Operation) Next, the operation of the starter described above will be explained with reference to the electrical circuit diagrams of Figs. 15A through 15C. When a key switch 10 is set to the start position by a driver, electricity flows from the battery 20 to the attracting coil 650 of the magnet switch 600. When current flows through the attracting coil 650, the plunger 610 is pulled by the magnetic force produced by the attracting coil 650, and the plunger 610 ascends from its lower position to its upper position. When the plunger 610 starts to ascend, together with the ascent of the plunger shaft 615 the upper movable contact 612 and the lower movable contact 611 ascend, and the rear end of the cord-shaped member 680 also ascends. When the rear end of the cord-shaped member 680 ascends, the front end of the cord-shaped member 680 is pulled down, and the regulating portion 232 descends. When the descent of the regulating portion 232 causes the return/rotation regulating claw 231 to mate with the convexes/concaves 214 of the periphery of the pinion 200, the lower movable contact 611 abuts the head portion 621 of the terminal bolt 620 (see Fig. 15A). The voltage of the battery 20 is impressed on the terminal bolt 620, and the voltage of the terminal bolt 620 is transmitted through the lower movable contact 611 → the resistor member 617 → the upper movable contact 612 → the lead wires 910a to the upper brushes 910. That is, the low voltage passing through the resistor member 617 is transmitted through the upper brushes 910 to the armature coils 530. Because the lower brushes 910 are constantly grounded through the brush holder 900, a current flows at low voltage through the armature coils 530 constituted in coil form by the paired upper layer coil bars 531 and lower layer coil bars 532. When this happens, the armature coils 530 generate a relatively weak magnetic force, this magnetic force acts on (attracts or repels) the magnetic force of the fixed poles 550, and the armature 540 rotates at low speed. When the armature shaft 510 rotates, the planetary gears 320 of the planetary gear speed reduction mechanism 300 are rotationally driven by the sun gear 310 on the front end of the armature shaft 510. When the planetary gears 320 exert a rotational torque through the planet carrier 330 on the internal gear 340 in the direction which rotationally drives the ring gear 100, the rotation of the internal gear 340 is limited by the operation of the overrunning clutch 350. That is, because the internal gear 340 does not rotate, the rotation of the planetary gears 320 causes the planet carrier 330 to rotate at low speed. When the planet carrier 330 rotates, the pinion 200 also rotates, but because the pinion 200 has its rotation limited by the return/rotation regulating member 230 the pinion 200 advances along the helical spline 221 on the output shaft 220. Together with the advance of the pinion 200, the shutter 420 also advances, and opens the opening portion 410 of the housing 400. The advance of the pinion 200 causes the pinion gear 210 to mesh completely with the ring gear 100 and then abut with the pinion stopping ring 250. Also, when the pinion 200 advances thus, the regulating claw 231 disengages from the convexes/concaves 214 of the pinion 200 and after that the front end of the regulating claw 231 drops to the rear side of the thrust bearing 215 disposed on the rear side of the pinion 200 so that the regulating claw 231 stops return of the pinion 200 to the rearward direction. With the pinion 200 advanced, the upper movable contact 612 abuts the abutting portion 631 of the fixed contact 630. When this happens, the battery voltage of the terminal bolt 620 is directly transmitted through the upper movable contact 612 → the lead wires 910a to the upper brushes 910. That is, a high current flows through the armature coils 530 consisting of the upper coil bars 531 and the lower coil bars 532, the armature coils 530 generate a strong magnetic force and the armature 540 rotates at high speed. The rotation of the armature shaft 510 is slowed and has its rotational torque increased by the planetary gear speed reduction mechanism 300 and rotationally drives the planet carrier 330. At this time, the front end of the pinion 200 abuts the pinion stopping ring 250 and the pinion 200 rotates integrally with the planet carrier 330. Because the pinion gear 210 of the pinion 200 is meshing with the ring gear 100 of the engine, the pinion gear 210 rotationally drives the ring gear 100 and rotationally drives the output shaft of the engine. Next, when the engine starts and the ring gear 100 of the engine rotates faster than the rotation of the pinion 200, the action of the helical spline creates a force tending to retract the pinion 200. However, the regulating claw 231 which has dropped to behind the pinion 200 prevents the pinion 200 from retracting, prevents early disengagement of the pinion 200, and enables the engine to be started surely (see Fig. 15B). When the engine starting causes the ring gear 100 to rotate faster than the rotation of the pinion 200, the rotation of the ring gear 100 rotationally drives the pinion 200. When this happens, the rotational torque transmitted from the ring gear 100 to the pinion 200 is transmitted through the planet carrier 330 to the pins 332 which support the planetary gears 320. That is, the planetary gears 320 are driven by the planet carrier 330. When this happens, because a torque rotationally opposite to that during engine starting is exerted on the internal gear 340, the overrunning clutch 350 allows the rotation of the ring gear 100. That is, when a torque rotationally opposite to that during engine starting is exerted on the internal gear 340, the roller 353 of the overrunning clutch 350 detaches to outside the concave portion 355 of the clutch inner 352 and rotation of the internal gear 340 becomes possible. In other words, the relative rotation with which the ring gear 100 rotationally drives the pinion 200 when the engine starts is absorbed by the overrunning clutch 350, and the armature 540 is never rotationally driven by the engine. When the engine starts, the driver releases the key switch 10 from the start position and the flow of current to the attracting coil 650 of the magnet switch 600 is stopped. When the flow of current to the attracting coil 650 stops, the plunger 610 is returned downward by the action of the compression coil spring 660. When this happens, the upper movable contact 612 moves away from the abutting portion 631 of the fixed contact 630, and after that the lower movable contact 611 also moves away from the head portion 621 of the terminal bolt 620, and the flow of current to the upper brushes 910 is stopped. When the plunger 610 is returned downward, the action of the return spring portion 233 of the return/rotation regulating member 230 causes the return/rotation regulating claw 231 to return upward, and the return/rotation regulating claw 231 moves away from the rear of the pinion 200. When this happens, the pinion 200 is returned rearward by the action of the return spring 240, the meshing of the pinion gear 210 with the ring gear 100 of the engine is disengaged, and the rear end of the pinion 200 abuts the tapered portion 222 of the output shaft 220. That is, the pinion 200 is returned to the position it was in before the starter was started (see Fig. 15C). Also, the plunger 610 being returned downward causes the lower movable contact 611 to abut with the upper face of the stationary core 642 of the magnet switch 600, and the lead wires of the upper brushes 910 conduct electrical current in the order the upper movable contact 612 → the resistor member 617 → the lower movable contact 611 → the stationary core 642 → the magnet switch cover 640 → the brush holder 900. In other words, the upper brushes 910 and the lower brushes 910 short-circuit through the brush holder 900. Meanwhile, inertial rotation of the armature 540 generates an electromotive force in the armature coils 530. Because this electromotive force is short-circuited through the upper brushes 910, the brush holder 900 and the lower brushes 910, a braking force is exerted on the inertial rotation of the armature 540. As a result, the armature 540 rapidly stops. (Advantages) In the state in which the return/rotation regulating claw 231 is positioned rearward the pinion 200 and the return of the pinion 200 from the ring gear 100 is regulated, the thrust bearing 215 absorbs the difference between the rotational speed of the pinion 200 and that of the return/rotation regulating claw 231. Because the rotation of the pinion 200 is absorbed by the thrust bearing 215, and the rotation torque of the pinion 200 is prevented from being transmitted to the return/rotation regulating claw 231, generation of wear, heat, and rotation loss between the pinion 200 and return/rotation regulating claw 231 can be prevented. Further, when the pinion 200 is driven by the ring gear 100 and rotates at a higher speed than the output shaft 220 and consequently the force for moving the pinion 200 rearward is applied to the pinion 200 due to the difference in the rotational speeds, a great load is applied between the pinion 200 and the return/rotation regulating claw 231. The thrust bearing 215, however, absorbs the difference between the rotational speeds, the generation of wear, heat, and rotation loss between the pinion 200 and return/rotation regulating claw 231 can be prevented, which allows the performance of the starter to be maintained for a long time. In this embodiment, because the thrust bearing 215 comprises an orbital ring 216 and a rolling bearing composed of the orbital ring 216 and a plurality of spheres 217, the rotational force is transmitted to the return/rotation regulating claw 231 at a very small degree. Thus, even though the return/rotation regulating claw 231 having a low rigidity is used, there is no disadvantage that the return/rotation regulating claw 231 is damaged by the engagement into the rotation of the pinion 200. Moreover, because the rigidity of the return/rotation regulating claw 231 is allowed to be low, the force of the magnet switch 600 for operating the return/rotation regulating claw 231 can be reduced and hence, the magnet switch 600 can be allowed to be compact and light. According to this embodiment, the pinion 200 can be moved in the axial direction of the output shaft 220 which drives the pinion 200, and the weight of the moving member (pinion 200 + thrust bearing 215) can be allowed to be smaller by about 1/5 than that of the conventional moving member (pinion + pinion shaft). Further, because the pinion 200 can be moved axially by utilizing the rotational force of the motor 500, the force required for the magnet switch 600 is the force for operating the movable contacts 611 and 612 plus the force for operating the return/rotation regulating claw 231. Thus, the force to be generated by the magnet switch 600 is much smaller than that to be generated by the conventional one. Therefore, the magnet switch 600 can be made smaller and lighter than the conventional one. In addition, because the weight of the moving member can be allowed to be smaller by about 1/5 than that of the conventional one, the energy for moving the pinion 200 can be allowed to be smaller than that for moving the conventional one. Because of this, the energy required for actuating the starter can be reduced and hence, the load to be applied to a power unit (lead storage battery, electric double-layer capacitor or the like) for driving the starter can be reduced. Consequently, the power unit can be allowed to be smaller and have a longer life than the conventional one. Moreover, because the weight of the moving member can be allowed to be smaller by about 1/5 than that of the conventional one, the shock generated when the pinion 200 engages the ring gear 100 can be reduced. The pinion 200 is heat-treated after the thrust bearing 215 is mounted thereon. Therefore, it is unnecessary to subject the orbital ring 216 of the thrust bearing 215 to heat treatment separately, which eliminates the need for a process of increasing the hardness of the orbital ring 216 to more than a predetermined value. Further, the return/rotation regulating claw 231 is positioned rearward the pinion 200 because it exceeds the expansion force of the return spring portion 233 by the movement force of the plunger 610 of the magnet switch 600. Thus, when the magnet switch 600 is turned off, the return/rotation regulating claw 231 can be securely disengaged from the rear portion of the pinion 200 owing to the expansion force of the return spring 233. [Second Embodiment] Fig. 16 is a sectional view of a starter according to a second embodiment. While in the first embodiment the magnet switch 600 is positioned rearward the motor 500 and the plunger 610 is positioned in a direction orthogonal to the armature shaft 510 of the motor 500, in a starter of the second embodiment, a magnet switch 600 is positioned below a motor 500 with its plunger being positioned in a direction parallel with an armature shaft 510 of the motor 500. [Third Embodiment] Fig. 17 shows a third embodiment in a sectional view of a pinion 200 having a thrust bearing 215 mounted thereon. In the abovedescribed first and second embodiments, the pinion gear 210 (outer teeth) is formed on the peripheral face of one member and the helical inner spline 211 (inner teeth) is formed on the inner peripheral face thereof. Unlike the first and second embodiments, in a pinion 200 of the third embodiment, a pinion inner member 200a provided with a helical inner spline 211 on the inner peripheral face thereof and a pinion outer member 200b provided with a pinion gear 210 on the peripheral face thereof are separately produced, and then nonrotatably fixed with each other. As an example of a method of fixing the two members 200a and 200b, press fitting method may be utilized after providing a whirl-stop (for example, key way) between the pinion inner member 200a and the pinion outer member 200b or welding method may be used. In the first and second embodiments, it is difficult to form both the pinion gear 210 and the helical inner spline 211 on one member by cold forging. Thus, in the first and second embodiments, the pinion gear 210 which is the external teeth has to be formed by machining. In this third embodiment, however, those can be formed by cold forging, respectively, which results in a reduction in manufacturing cost. Furthermore, the pinion inner member 200a can be connected with many kinds of pinion outer members 200b. Therefore, many kinds of pinions 200 can be manufactured by preparing many kinds of pinion outer members 200b. That is, in the case of the pinion 200, many kinds of specifications are required according to the specification of the engine, whereas in the case of the helical inner spline 211, only one kind or a few kinds of specifications are required. Thus, many kinds of pinions 200 can be manufactured in combination of the pinion inner member 200a and the pinion outer member 200b provided separately, which provides many kinds of starters corresponding to many kinds of engines. Further, the pinion inner member 200a can be mass-produced, which leads to the production of the pinion 200 in low cost. The pinion 200 of this embodiment is heavier than that of the first and second embodiments because of a cold forging-caused shear droop portion 210a of the pinion outer member 200b, but the weight of the pinion 200 of this embodiment is much lighter than that of the conventional pinion moving member. Thus, the third embodiment can provide the similar operation and effect as in the first embodiment. [Fourth Embodiment] Figs. 18 through 21 show a fourth embodiment in which a rotation regulating member and a return regulating member are provided separately. The construction of the return regulating member of this embodiment is different from that of the return regulating member of the first embodiment. The construction of the return regulating member of this embodiment will be described below. A return regulating member 260 (corresponding to return regulating means) comprises an annular portion 262 (Fig. 19) having a circular hole 261 formed at the center thereof to receive an output shaft 220 therethrough; side portions 263 bent at right angle to the annular portion 262 at both sides thereof; and a pivotal support 264 pivotably supported by a supporting pin 270 fixed to a center bracket 360. The return regulating member 260 is constructed by mating the supporting pin 270 with a hole 265 (Fig. 20) formed on the pivotal support 264 and by mating an engaging pin 281 provided on a thrust ring 280 with a slot 266 formed on the side portion 263, so that the return regulating member 260 is rotatable or pivotable around the supporting pin 270. The return regulating member 260 is pressed toward a plate 290 by a spring 271 mating with the supporting pin 270. That is, the spring 271 presses the pinion 200 rearward (toward the plate 290) through the return regulating member 260, thus maintaining a stationary state and contributing to preventing the pinion 200 from moving forward when the engine is started. As shown in Fig. 20, the rotation regulating member 230 of this embodiment is formed of a circular rod-shaped metal material, and both ends thereof are bent perpendicularly in the same direction at opposite positions in a radial direction thereof. One end of the bent portion serves as a rotation regulating bar 231 which engages convexes/concaves 214 of the pinion 200 to stop rotation of the pinion 200 at an initial time in the actuation of the starter, whereas one end of a cord-shaped member 680 engages the other end 231b of the rotation regulating member 230 to transmit the operation of the magnet switch 600 therethrogh. Further, as shown in Fig. 21, when the return regulating member 260 is inclined axially by a forward movement of the pinion 200, the rotation regulating bar 231 enters into a rear portion of the annular portion 262 of the return regulating member 260, thus maintaining the posture of the return regulating member 260 by supporting an end of the annular portion 262. The operation of this embodiment is described below. Similarly to the first embodiment, when a starter switch is turned on, the magnet switch 600 is actuated, and consequently, the rotation regulating bar 231 of the rotation regulating member 230 engages the convexes/concaves 214 of the pinion 200, thus regulating the rotation of the pinion 200. Receiving the rotational force of the starter motor 500, the output shaft 220 rotates and the rotation-regulated pinion 200 advances on the helical spline. As a result, the pinion 200 engages the ring gear 100 to start the engine. As shown in Fig. 21, at this time, the return regulating member 260 biased by the spring 271 is inclined axially around the supporting pin 270 by the advance of the pinion 200, with the engaging pin 281 mounted on the thrust ring 280 and the slot 266 formed on the side portion 263 engaging each other. When the pinion 200 engages the ring gear 100 completely, the leading end of the rotation regulating bar 231 disengages from the convexes/concaves 214 of the pinion 200 and is placed at the rear side of the thrust ring 280, thus permitting the rotation of the pinion 200 and supporting the rear end of the return regulating member 260. Therefore, the posture of the return regulating member 260 inclined axially by being pulled by the thrust ring 280 is maintained. Owing to the above, when the pinion 200 is rotated by the ring gear 100 and a retraction force is applied to the pinion 200, the retraction of the pinion 200 can be prevented by the cooperation of the return regulating member 260 and the rotation regulating member 230. Thereafter, when the starter switch is turned off, the rotation regulating member 230 is raised up in Fig. 21 and returned to the original position by the force of the return spring. As a result, the leading end of the rotation regulating bar 231 disengages from the rear end of the return regulating member 260, thus returning the pinion 200 to the stationary state (Fig. 18.) together with the return regulating member 260. In this embodiment, the return regulating member 260 is rotatably mounted relative to the pinion 200 through the thrust ring 280, and the rotational force of the pinion 200 is not applied to the rotation regulating bar 231 supporting the rear end of the return regulating member 260. Therefore, the rotation regulating bar 231 is prevented from being bent or worn. Further, because the side portions 263 of the return regulating member 260 contact the rear end face of the thrust ring 280 at both positions in a radial direction thereof, the pinion 200 is supported by two points. Owing to this, the pinion 200 can be prevented from being inclined with respect to the output shaft 220 and hence, a reliable operation can be provided. [Modification] Although in each of the embodiments only the pinion 200 engages the helical outer spline 221 of the output shaft 220, it is possible to design a starter to have a pinion moving member composed of the pinion 200 and separate functional parts (for example, one-way clutch or the like) mounted thereon and engageable with the helical outer spline 221 of the output shaft 220.

Claims: A starter comprising: an output shaft (220) having a helical spline (221) thereon; a pinion moving member having a pinion (200) engageable with a ring gear (100) of an engine, wherein the pinion moving member is mounted axially movably through an engagement with the helical spline (221) of the output shaft (220); a motor (500) for driving the output shaft (220), said motor (500) moving the pinion (200) to a ring gear side by a difference of rotational speed relative to the pinion moving member to engage the pinion (200) with the ring gear (100); return regulating means (230; 260) for preventing and regulating a return of the pinion (200) from the ring gear (100) when the pinion (200) has engaged the ring gear (100) through the pinion moving member; characterized in that it further comprises: absorbing means (215) provided between the pinion (200) and the return regulating means (230; 260) and absorbing a difference between a rotational speed of the pinion (200) and that of the return regulating means (230; 260), the absorbing means (215) excluding a sliding-type bearing. A starter according to claim 1, wherein said absorbing means (215) is a torque-reduction suppressing means for preventing loss of rotational torque in spite of a difference between a rotational speed of the pinion (200) and that of the return regulating means (230; 260). A starter according to claim 1, wherein: the absorbing means (215) includes a rolling bearing (216-218) provided on the pinion moving member. A starter according to any one of claims 1 through 3, further comprising: rotation regulating means (230) for regulating a rotation of the pinion (200) by contacting therewith, the rotation regulating means (230) being adapted to move into a position adjacent to the pinion (200) and opposite to the pinion (200) when the pinion (200) moves to the ring gear side by a predetermined distance, thus acting as the return regulating means for regulating the return of the pinion (200) from the ring gear (100). A starter according to any one of claims 1 through 4, wherein: the pinion moving member includes: a pinion inner member (200a) engaged with the helical spline (221) of the output shaft (220), and a pinion outer member (200b) having a pinion gear rotatable integrally with the pinion inner member. A starter according to any one of claims 1 through 3, further comprising: rotation regulating means (230) provided separately from the return regulating means for regulating a rotation of the pinion (200) by contacting therewith, the rotation regulating means (230) being adapted to move into a position adjacent to the pinion (200) and opposite to the pinion (200) when the pinion (200) moves to the ring gear side by a predetermined distance. A starter according to claim 6, wherein: the return regulating means is pivotably supported and coupled with the pinion (200) to be movable therewith. A starter according to claim 7, wherein: the return regulating means has a plurality of sides (263) contacting the pinion moving means at a plurality of locations around a central axis of the pinion moving member.

Inventors: ARAKI TAKESHI, HAYASHI NOBUYUKI, KATOH MASAHIRO, NIIMI MASAMI, OHMI MASANORI, SHIGA TSUTOMU, ARAKI, TAKESHI, HAYASHI, NOBUYUKI , KATOH, MASAHIRO, NIIMI, MASAMI, OHMI, MASANORI, SHIGA, TSUTOMU
Applicants: DENSO CORP, DENSO CORPORATION
Application year: 1996
Main classification: F02N15
IPC codes: F02N15