EP1052402A2

EP1052402A2 - Starter having a pinion movement control structure

Info

Publication number: EP1052402A2
Application number: EP00116717A
Authority: EP
Inventors: Takeshi c/o Denso Corporation Araki; Masahiro c/o Denso Corporation Soh
Original assignee: Denso Corp
Current assignee: Denso Corp
Priority date: 1996-07-10
Filing date: 1997-06-06
Publication date: 2000-11-15
Also published as: EP1052402A3

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.
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.

SUMMARY OF THE INVENTION

The present invention has the object to provide a starter which reduces an impact between a pinion and a ring gear upon meshing.

This object is solved by the subject matters of claims 1, 6 and 11.

According to the present invention, for attaining the object, there is provided a structure by which a pinion moving body is advanced a predetermined distance toward a ring gear and then a starting motor is turned on, so that the pinion meshes with the ring gear when the rotation speed is still low.

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 a first embodiment of the present invention;

Fig. 2 is a perspective view of a pinion rotation restricting member used in the first embodiment;

Fig. 3 is a plan view of a pinion moving body as viewed from the front side in the first embodiment;

Fig. 4 is a sectional view showing a state of a pinion gear in engagement with a ring gear in the first embodiment;

Fig. 5 is a sectional view of a starter according to a second embodiment of the present invention;

Fig. 6 is a plan view of a pinion moving body as viewed from the front side in the second embodiment;

Fig. 7 is a sectional view showing a starter according to a third embodiment of the present invention;

Fig. 8 is a perspective view showing a rotation restricting member used in the third embodiment;

Fig. 9 is a front view of a pinion movement control structure in the third embodiment;

Fig. 10 is a sectional view showing the operation of the starter before starting motor rotation in the third embodiment;

Fig. 11 is a sectional view showing the operation of the starter during starting motor rotation in the third embodiment; and

Fig. 12 is a plan view of a starter according to a fourth embodiment of the present invention.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

The present invention will be described with reference to various embodiments shown in the drawings.

(First Embodiment)

Referring to Fig. 1, a starter 100 according to this embodiment comprises a starting motor 102 for generating rotational force, a planetary reduction gear (reduction gear) to reduce rotation of the starting motor 102, an output shaft 103 rotating upon being subjected to rotational output of the reduction gear, a pinion moving body 104 fitted onto the output shaft 103, an electromagnet switch 105 for controlling the supply of electric current to the starting motor 102, and a coil-shaped elastic member 106 (Fig. 2) and the like. The starter 100 is covered with outer housings having an external form of a substantially cylindrical shape. The outer housings are made up of a front housing 107, center casing 108, a yoke 109, a brush holder 110, and a rear casing 111, all of which are secured in the axial direction by tightening up a plurality of through bolts.

The starting motor 102 is constructed so that a fixed magnetic pole 112 (for example, a plurality of permanent magnets) is secured to the inner periphery of the yoke 109 serving as a magnetic frame as well as a part of the outer housing. An armature 113 is rotatably disposed within the inner periphery of the fixed magnetic pole 112, and brushes 115 is placed over a commutator 114 provided at the axial end of the armature 113.

The yoke 109 in a cylindrical shape has one end side which is set inside an open end of the center casing 108 in a spigot-joint manner, while the other end side thereof is set inside an open end of the brush holder 110 in a spigot-joint manner.

The armature 113 has a rotation shaft 116 one end of which is inserted into a recess 103a formed at the rear end of the output shaft 103 and is rotatably supported via a bearing 117 fitted into the inner periphery of the recess 103a.

The commutator 114 is formed of a plurality of commutator bars combined into a cylindrical shape on the outer periphery of the other end side of the rotation shaft 116. The brush 15 is disposed in a brush casing 120 formed of the brush holder 110 and a plate 119 and biased by a spring 121 to the outer periphery of the commutator 114. However, the brush 115 is subject to movement restriction in the rotational direction with the brush casing 120 being radially (upward and downward directions in Fig. 1) slidably.

The reduction gear comprises a sun gear 122 (outer teeth) formed on the outer periphery of one end side of the rotation shaft 116, an internal gear 123 (inner teeth) radially located on the outer periphery of the sun gear 122, and a plurality of planetary gears 124 placed between the sun gear 122 and the internal gear 123 and in mesh with both

gears

122 and 123.

The internal gear 123 is formed on the inner periphery side of a gear forming member 125 disposed in the inner periphery of the center casing 108. The gear forming member 125 which makes up, together with an inner cylindrical part 108a and rollers 126, a one-way clutch via the rollers 26 between the gear forming member 125 and the inner cylindrical part 108a of the center casing 108, is unrotatably provided in the rotational direction of the armature 113 and rotatably set up against the rotational direction thereof with respect to the center casing 108 through operation of the one-way clutch.

The planetary gear 124 is rotatably supported via a bearing 128 fitted onto the outer periphery of a pin 127 which is pressed into a large-diameter part 103A set up on the outer periphery of the rear end of the output shaft 103.

The output shaft 3 is coaxially provided with the rotation shaft 116, one end thereof being rotatably supported via a bearing 129 held in the front casing 107 and the other end side being rotatably supported via a bearing 130 held in the inner cylindrical part 108a of the center casing 108, while the axial movement thereof relative to the center casing 108 is restricted. On the outer periphery side of the output shaft 103 projecting forward (left direction in Fig. 1) of the center casing 108 is formed a helical spline 103b onto which a helical spline 104a formed on the inner periphery of the pinion moving body 104 is fitted.

The pinion moving body 104 is integrally formed a pinion gear 132 for meshing with a ring gear 31 set up on a drive shaft of an engine, and a flange 133 having an outer diameter larger than that of the pinion gear 132 as well as a multiplicity of protrusions and recesses 133a on the outer periphery thereof is integrally formed on the rear end side (right end side in Fig. 1) of the pinion gear 132. Also, on the rear end side of the pinion moving body 104 is disposed a washer 135 which is rotatably supported via rollers 134.

The pinion moving body 104 is normally biased toward the ring gear 131 by means of a spring 136 interposed between the washer 135 and the center casing 108.

The electromagnet switch 105 is housed in the rear casing 111 in the rear of the brush holder 110. The electromagnet switch 5 is made up of an attraction coil 137 for generating magnetic force upon receiving electric current, a plunger 138 movably provided in the inner periphery of the attraction coil 137, an external terminal (explained below) providing connection to outside wiring, and a motor contact (explained below) interposed in a circuit for supplying current to the armature 113, and the like. The electromagnet switch 105 is disposed so that the moving directions of the plunger 38 lies in the radial direction of the starter 1 (upward and downward directions in Fig. 1).

The external terminal is a switch terminal (not illustrated herein) which is connected to wiring from a battery terminal 139 to which a battery cable is connected to a battery through a key switch. The motor contact comprises a movable contact 142 which is attached via an insulation member 141 to the end of a rod 140 interlocked to the plunger 138, a battery-side fixed contact 143 which is integrally formed with the battery terminal 139, and a motor-side fixed contact (not illustrated) which is connected to the brush 115. Both fixed contacts 143 are turned on as the movable contact 142 abuts both fixed contacts 143 with the movement of the plunger 138.

The coil-shaped elastic member 106 is, as shown in Fig. 2, formed, for example, by winding a metallic rod around in a coil shape, both ends thereof 6a and 6b bent approximately orthogonally to the same direction.

The pinion rotation restricting member 106 is placed so that a part thereof wound around in the coil shape is provided movably in the upward and downward directions in a space formed between the center casing 108 and a plate 144 placed fixedly on the front side thereof. Both

ends

106a and 106b of the member 106 are bent at right angles passing through

slots

144a and 144b (Fig. 3) formed in the plate 144 to be picked up on the forward side of the plate 144.

However, one end (lower protrusion) 106a is located radially at the lower side of the pinion moving body 104 and a tip 106c is formed in a hook shape (hook 6c) for engaging the front end side of the flange 133 and normally restricting forward movement of the pinion moving body 104 biased forward by the spring 136. The other end (upper protrusion) 106b is radially positioned on the upper side of the pinion moving body 104 a predetermined distance away from the outer periphery of the flange 133.

The lower protrusion 106a to which one end of a cord-like connection member 145 is interlocked, is in engagement with a spring 146 (Fig. 3) and is in the state of being normally biased upward in Fig. 1 due to the reaction of the spring 146. It is to be noted that the other end of the cord-like member 145 is interlocked to the bottom of the plunger 138.

While the starter 1 is in the stationary state, spacings L10, L20, and L30 are established so that the following relationship will hold, with L10 representing a hooking distance between the hook 106c of the lower protrusion 106a of the pinion rotation restricting member 106 and the flange 133 of the pinion moving body 104, L20 representing a distance between the upper protrusion 106b of the rotation restricting member 106 and the outer periphery side of the flange 133 of the pinion moving body 104, and L30 representing a distance between the movable contact 142 of the electromagnet switch 105 and both fixed contacts 143. L10 ≦ L20 ≦ L30

Also, length of the upper protrusion 106b is set so that even when the pinion moving body 104 subjected to the biasing of the spring 136 moves forward the predetermined distance (for example, when a movement is made to a position whereat the front end side of the pinion gear 132 abuts the rear end side of the ring gear 131 or when a movement is made to the close vicinity of the rear end side of the ring gear 131), the protrusion 106b may be kept received in the recesses 133a of the flange 133 upon moving downward of the pinion rotation restricting member 106.

Next, operation of this embodiment will be explained.

Upon closing of the key switch, electric current flows from the battery to the attraction coil 137 of the electromagnet switch 105. The attraction coil 137 generates magnetic force to attract the plunger 138 upward in Fig. 1 due to the magnetic force.

With the movement of the plunger 138, the pinion rotation restricting member 6 is pulled through the cord-like member 145 to move downward in Fig. 1 while flexing the spring 146.

When the pinion rotation restricting member 106 moves the predetermined distance L10, the hook 106c of the lower protrusion 106a disengages from the flange 133 of the pinion moving body 104, releasing the movement restriction on the pinion moving body 104. The pinion moving body 104 is advanced forward toward the ring gear 131 by the biasing of the spring 136.

When the plunger 138 moves further upward and the pinion rotation restricting member 106 moves downward by means of the cord-like member 145, the upper protrusion 106b of the pinion rotation restricting member 106 is set into the recesses 133a provided on the outer periphery of the flange 133 of the pinion moving body 104, thereby restricting the rotation of the pinion moving body 104.

On the other hand, due to the movement of the plunger 138, the movable contact 142 abuts both fixed contacts 143 to close the motor contact. As a result, the armature 113 starts rotating. After the rotation of the armature 113 is reduced by the reduction gear, the rotation is transmitted to the output shaft 103, which starts rotating.

The rotation of the output shaft 103 causes the pinion moving body 104 to tend to rotate. As the rotation of the pinion moving body 104 is restricted so that the rotation force of the output shaft 103 acts upon the pinion moving body 104 through the helical spline 103b as propulsion. This causes the pinion gear 132 to mesh with the ring gear 131 (Fig. 4) so that the rotation force of the starting motor 102 (rotation of the output shaft 103) is transmitted to the ring gear 131 to drive the engine.

When the pinion gear 132 meshes with the ring gear 131, as shown in Fig. 4, the upper protrusion 106b of the pinion rotation restricting member 106 is pulled down in the rear of the washer 135 which is rotatably provided on the rear end side of the pinion moving body 104 to restrict retreat of the pinion moving body 104. Under this condition, a hooking distance from the uppermost outer periphery side of the flange 133 of the pinion moving body 104 to the upper protrusion 106b of the pinion rotation restricting member 106 is L50, and a distance from the lowermost outer periphery side of the flange 133 to the hook 106c of the lower protrusion 106a of the pinion rotation restricting member 106 is L40. The distances L40 and L50 must be set so that the following relationship will hold. L50 ≦ L40

When the key switch is turned off upon completion of starting the engine, the electric current to the attraction coil 137 of the electromagnet switch 137 is interrupted, resulting in the pinion rotation restricting member 106 to be pushed back upward in Fig. 1 by the reaction of the spring 146. As a result, the upper protrusion 106b disengages from the washer 135 of the pinion moving body 104 and releases the retreat restriction of the pinion moving body 104.

Since the rotation speed of the ring gear 131 (engine rotation) exceeds that of the pinion gear 132 (rotation of the output shaft 103), a retreating force in reverse direction to the direction of meshing acts in between the helical spline 103b of the output shaft 103 and the helical spline 104a of the pinion moving body 104. This retreating force causes the pinion moving body 104 to retreat on the output shaft 103 against the spring 136 upon releasing of retreat restriction by the upper protrusion 106b of the pinion rotation restricting member 106, releasing the meshing between the ring gear 131 and the pinion gear 132.

Also, when the pinion rotation restricting member 106 moves upward due to the reaction of the spring 146, the plunger 138 is pulled downward in Fig. 1 by the cord-like member 145. Hence, with the downward movement of the plunger 138, the movable contact 142 leaves both fixed contacts 143 and opens the motor contact, thereby stopping current supply to the armature 113 and halting the rotation of the armature 113.

Further, when the pinion moving body 104 retreats to the stationary position (position shown in Fig. 1), the hook 106c of the lower protrusion 106a of the pinion rotation restricting member 106 which is moving upward engages the front end side of the flange 133 of the pinion moving body 104, resulting in restriction on the advance movement of the pinion moving body 104.

According to this embodiment, inasmuch as the pinion moving body 104 is normally biased by the reaction of the spring 136 toward the ring gear 131, upon releasing of the movement restriction of the pinion moving body 104 by means of the hook 106c of the lower protrusion 106a of the pinion rotation restricting member 106, the pinion moving body 104 biased by the spring 136 can move over toward the ring gear 131.

This makes it possible to restrict rotation of the pinion moving body 104 while the front end side of the pinion gear 132 is in abutment with the rear end side of the ring gear 131 or while the pinion gear 132 is positioned in close vicinity of the ring gear 131, so that immediately after the armature 113 starts rotating, the pinion gear 132 can mesh with the ring gear 131.

As a result, a substantial abridgment of time from commencement of rotation of the armature 113 to the meshing of the pinion gear 132 with the ring gear 131 is accomplished, thereby enabling the pinion gear 132 to mesh with the ring gear 131 when the rotation speed is low, thus sharply restraining an impact occurring at meshing. Consequently, it is not necessary to increase the rigidity of the rotational force transmission part (each of the

gears

122, 123, and 124 of the reduction gear, the output shaft 103 and the like), so that an increase in weight and a larger-scale structure are not necessitated. This brings about significant advantages of size and weight reductions.

(Second Embodiment)

The starter 1 according to this embodiment includes, as shown in Fig. 5, a lever 148 which pushes the pinion moving body 104 forward by the reaction force of a spring 147, and a restricting member 149 (Fig. 6) which restricts the pinion lever being pushed forward by means of the lever 148.

The lever 148 is disposed in the rear of the washer 135 of the pinion moving body 104 and both ends thereof are pivotally supported about a pivot 150 provided on the plate 144, normally biasing the pinion moving body 104 forward due to the reaction of the spring 147.

As shown in Fig. 6, the restricting member 149 is pivotally supported about a pivot 151 which is disposed in close vicinity of the pinion rotation restricting member 106 in substantially parallel to the upper protrusion 106b, one end thereof having a hook 149a in engagement with the front end side of the flange 133 of the pinion moving body 104, and the other end thereof forking into two

legs

149b and 149c to grasp and hold the upper protrusion 106b of the pinion rotation restricting member 106 therewith.

Next, operation of this embodiment will be described.

As the attraction coil 137 of the electromagnet switch 105 is turned on to attract the plunger 138 upward in Fig. 5, the pinion rotation restricting member 106 interlocked to the plunger 138 by way of the cord-like member 145 moves downward against the biasing of the spring 146, whereupon the

fork legs

149b and 149c of the restricting member 149 moves following the movement of the upper protrusion 106b of the pinion rotation restricting member 106 so that the restricting member 149 pivots relative to the pivot 151 in the direction of arrow in Fig. 6.

This releases the movement restriction on the pinion moving body 104 as the hook 149a which has so far engaged the front end side of the flange 133 disengages therefrom, permitting the pinion moving body 104 to advance forward a predetermined distance by way of the lever 148 due to the reaction of the spring 147.

Thereafter, in the same way as in the first embodiment, commencement of rotation of the armature 113 while the pinion moving body 104 is in the rotation restriction by the upper protrusion 106b of the coil-shaped member 106, leads to the meshing of the pinion gear 132 with the ring gear 131 and the rotational force of the starting motor 102 (rotation of the output shaft 103) is transmitted to the ring gear 131 to drive the engine.

When the pinion gear 132 meshes with the ring gear 131, the upper protrusion 106b of the pinion rotation restricting member 106 falls in the rear of the washer 135 provided on the rear end side of the pinion moving body 104 to restrict retreat of the pinion moving body 104.

When the key switch is turned off after start of the engine, current to the attraction coil 137 of the electromagnet switch 105 is shut off and attraction force of the plunger 138 disappears so that the pinion rotation restricting member 106 is pushed upward in Fig. 5 by the reaction of the spring 146.

Accordingly, the upper protrusion 106b disengages from the washer 135 of the pinion moving body 104 and releases the retreat restriction on the pinion moving body 104, resulting in the pinion moving body 104 to retreat on the output shaft 103 and releasing the meshing of the ring gear 131 with the pinion gear 132.

The restriction member 149 following the movement of the upper protrusion 106b rotates about the pivot 151 in a reverse direction to that when the gears are meshed, whereby the hook 149a engages the front end side of the flange 133 of the pinion moving body 104 to perform, again, advance restriction thereof.

In the same way as in the first embodiment, according to this embodiment, while the front end side of the pinion gear 132 is in abutment with the rear end side of the ring gear 131 or while the pinion gear 132 is positioned in close vicinity of the ring gear 131, rotation restriction of the pinion moving body 104 is conducted.

Consequently, immediately after the armature 113 starts rotating, the pinion gear 132 can mesh with the ring gear 131, greatly restraining an impact value generating at the time of meshing and resulting in disposing of any need to raise the rigidity of the rotational force transmission part of the starter 100.

(Third Embodiment)

In this embodiment, as shown in Fig. 7, a starter 100 has a front casing or housing 202, a center casing 217, a yoke 203, a brush holder 205, and a rear casing 210. Through bolts (not illustrated) are used to couple the front casing 202 and the rear casing 210 sandwiching the center casing 217, the yoke 203 and the brush holder 205 therebetween. The brush holder 205 and the rear casing 210, each being made of an insulating resin molded member and lightweight, has small inertia moment from the front casing 202 to restrict the starter 100 from swinging and vibrating.

Inside the front casing 202 and the center casing 217, an output shaft 222 is rotatably supported by a bearing 231 affixed to the front casing 202 and by a bearing 232 coaxially affixed to an inner cylindrical part 217b of the center casing 217.

A torsion or helical spline 222c is formed on the outer periphery of the output shaft 222. The helical spline 222c of the output shaft 222 is engaged with the helical spline 226c formed on the inner periphery of a through hole in the radial center of a pinion moving body 226, which is axially movably held on the output shaft 222.

From the front part to the middle part of the pinion moving body 226 is integrally formed a pinion gear 226a which meshes with a ring gear 234 provided of an engine (for example, a crankshaft), while on the rear end flange of the pinion moving body 226 is likewise integrally formed protrusions and recesses 226d having an outside diameter larger than that of the pinion gear 226a. Moreover, on the rear end side of the pinion moving body 226 is disposed a washer 236 movement of which is restricted axially with respect to the pinion moving body 226 despite being axially and rotatably supported by rollers 235. Thus, a thrust bearing is formed by the rear end flange, the rollers 235 and the washer 236. Also, the pinion moving body 226 is subjected to constant pressing and biasing rearward by a biasing spring (compression coil spring) 229 which is in abutment with the front end side of the pinion moving body 226.

Inside the center casing 217 is housed a planetary reduction gear 250 composed of an internal gear 218, planetary gears 219, and a sun gear 208c. That is, the internal gear 218 is fixed in abutment with the inner periphery of the center casing 217, and the planetary gears 19 are in abutment with and in mesh with the internal gear 218. Each planetary gear 219 is supported by a pin 221 relative to each core by way of a bearing 220, each pin 21 being fixed to a flange forming the rear end of the output shaft 222. In the center of each planetary gear 219, there is disposed the sun gear 208c, which is formed around the tip of a rotation shaft 280 (armature shaft) of a starting motor 200, meshing with all planetary gears 219. Hence, the speed of rotation of the motor 200 is reduced to about thirty to forty percent via the planetary reduction gear 250, and transmitted the output shaft 222 to the pinion gear 226a.

The planetary reduction gear 250 and the motor 200 are separated by a partition 223. In the inner periphery of the front part of the internal gear 218, a one-way clutch is formed by the central cylindrical part 217b of the center casing 217 and a plurality of rollers 239 interposed therebetween.

The motor 200 comprises a stator 240 made up of the yoke 203 and a fixed magnetic pole 204, an armature 208 having the rotation shaft 280, and the brush holder 205 holding a plurality of brushes 206. The rotation shaft 280 of the motor 200 is rotatably supported by a bearing 232 fitted into the output shaft 222 and by a bearing 230 fitted into the brush holder 205.

A commutator 208a of a cylindrical shape is disposed at the rear of the armature 208 on the rotation shaft 280, whereas each brush 206 held in the brush holder 205 is biased toward the radial center by a spring 207 and is slidably in abutment with the commutator 208a by a predetermined pressure to be electrically connected thereto.

Inside the rear casing 210 is located and fixed an electromagnet switch 212 in the upward and downward directions. The electromagnet switch 212 has a movable core or plunger 214 and an electromagnetic attraction coil 213 for magnetically attracting the plunger 214, a movable contact 215 fixed to and held by a rod projecting upward from the plunger 214 on the upper part of the plunger 214.

A battery terminal 11 projects outwardly and is affixed to the upper part of the rear casing 210, while a battery-side fixed contact 211a electrically connected to the battery terminal 211 is secured to inside the upper part of the rear casing 210. Inside the rear casing 210, there is a motor-side fixed contact (not illustrated) adjacent to the fixed contact 211a with a predetermined distance in between which is electrically connected to the positive-side the brush 206 via coated wire (not illustrated).

A main switch 260 made up of the movable contact 215, fixed contact 211a, and another fixed contact (not illustrated) is mounted on the upper part of the inside space of the rear casing 210. When the attraction coil 213 is electrically connected to a battery (not illustrated), the plunger 214 is attracted into the attraction coil 213, the movable contact 215 moving upward with the plunger 214 to electrically connect the fixed contact 211a and other fixed contact and the main switch 60 closing to turn on the motor 200. A distance between the movable contact 215 and the fixed contact 211a is defined as L22.

One end 216a (rear end) of a cord-like member 216 composed of twisted stainless steel wire or the like is connected to the lower end of the plunger 214. The wire cable 216 extends downward from the end 216a, changes a direction thereof to forward at a pulley 216c rotatably supported by the rear casing 210, passes a groove formed through the lower part of the inside space of the rear casing 210 in the forward and rearward directions, and extends forward. The cord-like member 216, further extending forward along the outer periphery at the bottom of the brush holder 205, the yoke 203, and the center casing 217, is introduced to a groove formed in the bottom of the inside space of the front casing 202 in the forward and rearward directions. To keep the cord-like member 216 from being exposed a cover 238 over a protruding trough is attached to the bottom of the outer periphery lying at the lower part of the brush holder 205, the yoke 203, and the center casing 217, covering the cord-like member 216.

The cord-like member 216 introduced to the front casing 202 changes the direction thereof upward at a pulley 216d rotatably supported by the front casing 202 and the other end 216b (front end) thereof extends generally upward. The other end 216b has a tip connected to a lower protrusion 225b of a pinion rotation restricting member 225 which is elastic. Since the

pulleys

216c and 216d have sufficiently deep grooves the outer periphery of which lies in close vicinity to the inside walls of the rear casing 210 and the front casing 202, the cord-like member 216 will not disengage from the

pulleys

216c and 216d, even if slackening should occur.

The pinion rotation restricting member 225 is formed by bending a wire rod of spring steel or the like as shown in Fig. 28. The restricting member 225 bends at a right angle to the forward direction from the upper and lower ends of the body 225c of the generally coil shape, thereby providing an upper protrusion 225a and a lower protrusion 225b. A front end 225d (Fig. 8) of the lower protrusion 225b bends at a right angle to the right, forming a horizontal part of a predetermined length.

When the electromagnet switch 212 operates to pull the cord-like member 216, the upper protrusion 225a of the pinion rotation restricting member 225 moves downward in a through groove 224b (Fig. 7 and Fig. 9) to come into engagement with the protrusions and recesses 226d on the outer periphery of the pinion moving body 226 and restrict rotation of the pinion moving body 226. Even if the pinion moving body 226 advances a predetermined distance when the motor 200 is in rotating operation, the axial length of the upper protrusion 225a is so determined that it is kept engaged in the recesses 226d, until the pinion gear 226a meshes with the ring gear 234 in sufficient depth. It is long enough to restrict rotation of the pinion moving body 226. It is to be noted that an interval between the uppermost part of the outer periphery of protrusions and recesses 226d of the pinion moving body 226 and the upper protrusion 225a is defined as distance L21 which is shorter than the distance L22 in the main switch 260 in the electromagnet switch 212.

On the other hand, the lower protrusion 225b of the pinion rotation restricting member 225 has a middle part to which the other end 216b of the cord-like member 216 is welded, and the front end 225d extends through a groove 237c of a lever 237 and engages the lower half of the lever 237.

The upper protrusion 225a and the lower protrusion 225b extend through grooves 224b and 224c (Fig. 9) opened in the upper half and the lower half of the plate 224, projecting to the inside space of the front casing 202. Consequently, as shown in Fig. 9, the pinion rotation restricting member 225 is held movably upward and downward along the through grooves 224b and 224c.

Also, as shown in Fig. 9, a spring 233 (helical coil spring) with one end thereof fixed to the front side of the plate 224 pushes and urges the upper protrusion 225a upward. Thus, the pinion rotation restricting member 225 is normally biased upward. This means that except during operation of the electromagnet switch 212, the pinion rotation restricting member 225 is located at the upper end of the movable range. It is to be noted that since the coiled body 225c is housed in a spacing between the plate 224 and the bottomed part of the center casing 217, tilting of the pinion rotation restricting member 225 in each direction is restricted.

The lever 237 is has a shape in the form of a letter "<" and is formed by steel sheet blanking. The lever 237 is pivotally supported by a pivot 237a at the central part where the lever 237 is bent and the pivot 237a is held by a strut 224a which is set up integrally to project forward from the plate 224. The lower halt of the lever 237 is tilted in a direction of putting the lower end slightly forward and the through groove 237c is formed in the lower half. The front end 225d of the lower protrusion 225b of the pinion rotation restricting member 25 extends through the through groove 237c and is slidably engaged along the through groove 237c.

Accordingly, as soon as the electromagnet switch 212 operates to pull the pinion rotation restricting member 225 downward, the lower protrusion 225b thereof slides along the through groove 237c so that the lower half of the lever stands upright. As a result, an upper end 237b of the lever 237 located above the pivot 237a moves forward with the tilting of the lever 237. Since the upper end 237b is in abutment with the washer 236 which makes up the rear end side of the pinion moving body 226, the pinion moving body 226 is pushed by the upper end 237b up to the predetermined position ahead, which is, as shown in Fig. 10, the position where the pinion gear 226a is about to contact and mesh with the ring gear 234.

It is to be noted that, with the electromagnet switch 212 not operating, the distance L21 between the upper protrusion 225a of the pinion rotation restricting member 225 and the flange 226b of the pinion moving body 226 is set equal to or shorter than the distance L22 between the fixed contact 211a and the movable contact 215. During operation of the electromagnet switch 212, until the pinion rotation restricting member 225 is pulled down and engages the protrusions and recesses 226d, the main switch 260 which functions as a motor switch for supplying electric current to the motor 200 will not close.

The starter 100 of this embodiment operates as follows.

When current is supplied to the attraction coil 213 of the electromagnet switch 212 by through a key switch (not illustrated), the plunger 214 is magnetically attracted by the attraction coil 213 and moves upward, the cord-like member 216 is pulled toward the electromagnet switch 212, and the pinion rotation restricting member 225 is pulled down against the biasing of the spring 233 for restricting rotation of the pinion moving body 226. Thereupon, the front end 225d of the lower protrusion 225b of the pinion rotation restricting member 225 slides downward in the through groove 237c of the lever 237 to turn the lever 237 counterclockwise in Fig. 7.

In consequence, the upper end 237b of the lever 237 pushes the pinion moving body 226 from the rearmost position and advances the pinion moving body 226 the predetermined distance forward. At that time, the pinion moving body 226 advances while turning along the helical spline 222c of the output shaft 222 which is not in rotation yet. The washer 236 attached to the flange through rollers 236 does not turn so that no undue transverse force is applied to the upper end 237b of the lever 237. The pinion moving body 226 thus advances closely to the ring gear 234 as shown in Fig. 10. The upper protrusion 225a of the pinion rotation restricting member 225 comes into the recesses of the protrusions and recesses 226d of the pinion moving body 226, thus restricting rotation of the pinion moving body 226.

After the advance movement of the pinion moving body 226, the movable contact 215 of the main switch 260 abuts the battery-side fixed contact 11a and the motor-side fixed contact (not illustrated) to supply the motor 200 with electric current. Thus, the armature 208 starts rotating and rotation of the shaft 280 is reduced by the planetary reduction gear 250 to drive the output shaft 222. However, because rotation of the pinion moving body 226 is restricted by the pinion restricting member 225, the helical spline 222c of the output shaft 222 which has begun rotating starts pushing the pinion moving body 226 forward. As a result, pinion gear 226a starts meshing with the ring gear 234, and as shown in Fig. 31, upon reaching a predetermined meshing depth, the upper protrusion 225a of the pinion rotation restricting member 225 disengages from the protrusions and recesses 226d of the pinion moving body 226, thus releasing rotational restriction. Subsequently, the upper protrusion 225a moves slightly downward by the spring elasticity of the pinion rotation restricting member 225 and contacts the washer 236, thereby acting also to restrict retreat of the pinion moving body 226.

When the upper protrusion 225a disengages from the protrusions and recesses 226d to release rotational restriction in this manner, the pinion moving body 226, driven by the output shaft 222, starts rotating and begins driving the ring gear 234 for engine starting. Thereupon, a torque from the output shaft 222 acting on the pinion moving body 226 will exert a strong force due to drive of the motor 200 in pushing the pinion moving body 226 forward along the spline 222c.

Conversely, when the key switch is turned off after the engine starting, the attraction coil 213 is deenergized and magnetic force attracting the plunger 214 upward disappears. Thus, the plunger 214 returns downward, disabling the cord-like member 216 to pull the rotation restricting member 225 down. The pinion rotation restricting member 225 return upward by the spring elasticity of the spring 233, causing the upper protrusion 225a to leave the rear of the pinion moving body 226 and thus releasing retreat restriction of the pinion moving body 226.

Simultaneously with the return of the pinion rotation restricting member 225, the lever 237 also returns to the initial position, while the lower protrusion 225b of the pinion rotation restricting member 225 likewise takes a sliding course along the through groove 237c of the lever 237. Concomitant to return of the pinion rotation restricting member 225, the cord-like member 216 returns to the initial position with the plunger 214.

In this embodiment, the motor switch 260 closes to turn on the motor 200, after the pinion moving body 226 has already moved closely to the ring gear 234. Therefore, immediately after the output shaft 222 begins rotating and the pinion gear 226a starts further moving, the pinion gear 226a meshes with the ring gear 234. There passes only a short period of time from the beginning of rotating of the output shaft 222 until the beginning of meshing with the ring gear 234, the speed of rotation of the output shaft 222 is still low so that the pinion gear 226a comparatively slowly meshes with the ring gear 234. In consequence, meshing impact becomes slight, greatly reducing the impact load upon the driving system including the planetary reduction gear 250. Further, meshing engagement of the pinion gear 226a with the ring gear 234 under low speed condition will reduce chipping of the teeth of both

gears

226a and 234.

When the motor 200 is turned on and the output shaft 222 starts rotating, rotation of the pinion moving body 226 is kept restricted. Hence, for a short period after the output shaft 222 starts rotating, the pinion moving body 226 will not rotate so that through operation of the slipping on of the helical spline, the pinion moving body 226 is powerfully pushed out until meshing with the ring gear 234.

Moreover, the pinion rotation restricting member 225 and the lever 237 are in an integral structure and driven by the single movement of the plunger 214 of the electromagnet switch 12. Consequently, there is an advantage of even more improved reliability in operation at the time of the meshing of the pinion gear with the ring gear.

(Fourth Embodiment)

In this embodiment, as shown in Fig. 12, the rear casing 210 is shaped into a slim planar shape. That is, the inside space of the casing 210 is reduced to have a space housing mostly the electromagnet switch 212. The rear casing 210 which is secured to the brush holder 205 has a volume considerably decreased from that of the third embodiment. Since this means a weight reduction at a part of the longest moment arm from the starter mounting part which results in a considerable decrease of inertia moment, there is an advantage of further reduction in swinging vibration of the starter.

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 (102) for generating rotation force;

an output shaft (103) for rotating by transmission of the rotation force of the starting motor;

a pinion moving body (104) spline fitted on an outer periphery of the output shaft and having a pinion gear (132) for meshing with a ring gear (131) of an engine;

biasing means (136, 147, 148) to bias the pinion moving body toward the ring gear;

movement restricting means (106c, 149) to restrict normally movement of the pinion moving body toward the ring gear by the biasing means;

restriction releasing means (145) to release the movement restriction on the pinion moving body by the movement restricting means before rotation of the output shaft;

rotation restricting means (106) to restrict rotation of the pinion moving body upon movement of the pinion moving body to a predetermined position near the ring gear by the biasing means after the movement restriction of the pinion moving is released by the restriction releasing means; and

an electromagnet switch (105) for supplying electric current to the starting motor after rotation of the pinion moving body is restricted by the rotation restricting means.
A starter as claimed in claim 1, wherein:

the restriction releasing means includes a coupling member (145) connected to the movement restricting means and the electromagnet switch.
A starter as claimed in claim 1 or 2, wherein:

the rotation restricting means interlocks to the movement restricting means.
A starter as claimed in any one of claims 1 to 3, wherein:

the electromagnet switch is disposed on an opposite side of the pinion moving body of the starting motor.
A starter as claimed in claim 1, wherein:

the movement restricting means and the rotation restricting means are formed integrally in a single elastic member.
A starter comprising:

a starting motor (200) generating rotational driving force upon supply of electric current;

an output shaft (222) having a helical spline (222c) toned on an outer periphery thereof;

a pinion moving body (226) including a pinion gear (226a) for meshing with a ring gear (234) of an engine and axially movably supported on the output shaft;

pinion moving means (216, 237) for transferring the pinion moving body a predetermined distance toward the ring gear; and

an electromagnet switch (212) having an attraction coil (213), a plunger (214) movable to drive the pinion moving means, and a motor switch (260) responsive to the movement of the plunger, the motor switch supplying electric current to the motor after a transfer of the pinion moving body by the pinion moving means toward the ring gear so that upon commencement of rotation of the motor the pinion moving body is advanced via helical splines to engage the ring gear.
A starter as claimed in claim 6, further comprising:

rotation restricting means (225) for restricting rotation of the pinion moving body upon commencement of rotation of the motor.
A starter as claimed in claim 6, wherein:

the pinion moving means includes a lever (237) tiltably supported about a fulcrum (237a), the lever having one part (237c) linked with the plunger and another part (237b) abutting the pinion moving body.
A starter as claimed in claim 7, wherein:

the pinion moving body includes protrusions and recesses (226d) formed alternately radially on an outer periphery thereof;

the rotation restricting means has a first protrusion (225a) of a bar shape restricting rotation of the pinion moving body in engagement with the protrusions and recesses so that the first protrusion meshes with the protrusions and recesses as a result of the rotation restricting member being driven by movement of the plunger; and

the rotation restricting means has a second protrusion (225b) slidably engaged with a groove (237c) formed in the lever so that the second protrusion slides along the groove to tilt the lever for pushing out the pinion moving body toward the ring gear.
A starter as claimed in any one of claims 7 to 9, wherein:

the pinion moving means and the rotation restricting means are operatively linked to each other to be driven together by a single movement of the plunger before rotation of the motor.
A starter comprising:

a starting motor (102; 200);

an output shaft (103; 222) rotatable by the starting motor;

a pinion moving body (104; 226) axially movable on the output shaft and rotatable with the output shaft, the pinion moving body having a pinion gear (132; 226a) for meshing with a ring gear (131; 234) of an engine;

an electromagnet switch (105; 212) having a plunger (138; 214) arranged to move a first predetermined distance (L30; L22) to turn on a motor switch (142, 143; 260) through which electric current is supplied to the starting motor;

movement restricting means (106c, 149; 229) for normally restricting axial movement of the pinion moving body on the output shaft;

pinion moving means (136, 147, 148; 225b, 237) for moving the pinion moving body axially on the output shaft toward the ring gear in response to movement of the plunger;

rotation restricting means (106; 225) linked with the plunger to move a second predetermined distance (L20; L21) for engagement with the pinion moving body so that rotation of the pinion moving body is restricted at the time of meshing of the pinion gear with the ring gear; and

the first predetermined distance being set longer than the second predetermined distance so that the electromagnet switch enables rotation of starting motor only after movement of the pinion moving body toward the ring gear.