Starter

To reduce abrasion of the pinion and the ring gear, a coil spring and a plate are arranged between the inner circumference of the plunger and the output shaft. The plate is adapted to the rear end of the thrust spline of the over-running clutch to transmit the elastic force of the coil spring to the thrust spline.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 The present invention relates to a starter for starting an engine.
 2. Description of the Prior Art
 FIG. 9 is a sectional view showing an example of a conventional starter
 disclosed in Japanese Published Unexamined Patent Application No.
 10-159693-1998.
 In FIG. 9, 1A is an output shaft. An electromagnetic switch 2A, an
 over-running clutch 30A provided with a pinion 30P which meshes with a
 ring gear 50A, a plunger 40A comprising an inner plunger 4A and an outer
 plunger 4B, etc. are arranged coaxially on this output shaft 1A. A starter
 with this structure is generally called a coaxial type starter. 12A is an
 armature of a DC electric motor and 16A is a shaft (a motor shaft). 18A is
 a reduction mechanism which reduces the rotational force of the shaft 16A
 and transmits it to the output shaft 1A.
 8A is a contact shaft supported by an inner gear member 17A of the
 reduction mechanism 18A almost parallel with the plunger 40A through a
 supporting hole 17m.
 100 is a bracket and 800 is a shift plate which connects the outer plunger
 4B with the contact shaft 8A.
 The upper portion from the central axis in FIG. 9 shows the state of a
 starter not in operation and the lower portion shows the state wherein the
 starter is in operation with an electromagnetic switch turned ON and the
 pinion meshed with the ring gear.
 Next, the operation of the starter is explained. The operation will be
 explained referring also to FIG. 10, which is a partially enlarged view of
 FIG. 9.
 First, when an ignition switch is turned ON and current flows to an
 exciting coil 2B of the electromagnetic switch 2A, the outer plunger 4B is
 attracted by the exciting core 2C of the electromagnetic switch 2A. This
 conventional starter has such a structure that the outer plunger 4B is
 directly connected with the contact shaft 8A via the shift plate 800. When
 the outer plate 4B is attracted by the exciting coil 2B, the contact shaft
 8A is also moved simultaneously. Between the outer plunger 4B and the
 inner plunger 4A, there is a coil spring 401 mounted via a spring bracket
 400. The inner plunger 4A is kept in the stationary state because the coil
 spring 401 bends at the initial stage even when the outer plunger 4B is
 attracted and begins to move. In front of the inner plunger 4A, an inner
 clutch 30B is mounted via a shifter member 402 and as long as the inner
 plunger 4A is kept in the stationary state, the inner clutch 30B is also
 kept in the stationary state. After a short interval when the plunger 4B
 is attracted and begins to move, a movable contact 80A mounted on the
 contact shaft 8A comes into contact with a stationary contact 80B mounted
 in the contact chamber ZA. When the movable contact 80A is brought into
 contact with the stationary contact 80B, electric power is supplied from
 an external power source via a contact bolt 11A and an armature 12A begins
 to turn. When the output shaft 1A begins to turn by way of the reduction
 mechanism 18A, the pinion 30P is caused to move toward the ring gear 50A
 by a thrust generated in a helical spline portion 1B, and the threads and
 the thread grooves of the pinion 30P and the ring gear 50A agree and mesh.
 Thereafter, when the engine starts, the output shaft 1A and the pinion 30P
 are separated by the action of the overrunning clutch 30A and the pinion
 runs idle. When the power supply to the exciting coil 2B is stopped, the
 pinion 30P is disengaged from the ring gear 50A by return springs 403,
 404.
 However, in the case of a conventional starter disclosed in Japanese
 Published Unexamined Patent Application No. 10-159693-1998, the outer
 plunger 4B is directly connected with the contact shaft 8A by the shift
 plate 800. The contact shaft 8A also moves simultaneously with the
 attraction and movement of the outer plunger 4B and therefore, the movable
 contact 80A immediately comes into contact with the stationary contact 80B
 and the armature 12A begins to rotate before the end surface 30Pe of the
 pinion 30P comes into contact with the end surface 50Ae of the ring gear
 50A.
 That is, according to the above conventional starter, the pinion 30P meshes
 with the ring gear 50A by rotating the pinion 30P by driving the armature
 12. However, in the above starter, the thrust generated in the helical
 spline portion 1B is insufficient to press the pinion 30P toward the ring
 gear 50A and the coil spring 401 is also incapable of pressing the pinion
 30P toward the ring gear 50A. Therefore, when meshing with the ring gear
 50A, the pinion 30P is often repelled by the ring gear 50A and tries again
 to mesh with it.
 Accordingly, the pinion 30P does not mesh with the ring gear 50A smoothly
 and reliability when the pinion 30P meshes inadequately with the ring gear
 50A. In addition, the gears are worn away and the life span of the gears
 is shortened.
 In the case of a starter with a structure wherein the contact shaft moves
 by the same amount as the outer plunger as in the above starter, it is
 required to secure a moving space for a plate (an engaging ring, etc.) to
 hold the coil spring 9S for pressing the contact shaft and the movable
 contact in the contact chamber and, as a result, the contact chamber
 inevitably becomes large.
 SUMMARY OF THE INVENTION
 The present invention was made to solve such problems as those mentioned
 above and its object is to provide a starter which is capable of meshing
 the pinion with the ring gear more smoothly than before, so that the
 pinion meshes with the ring gear in an excellent manner, reducing abrasion
 of the gears and thus, extending the life of the gears.
 Another object is to provide a starter that is capable of more smoothly
 meshing the pinion with the ring gear, downsizing the starter.
 In the starter of the present invention, an elastic means and a
 transmission means are provided between the inner circumference of the
 plunger and the outer circumference of the output shaft, and the
 transmission means is adapted to contact the rear end of the thrust spline
 to transmit an elastic force of the elastic means to the thrust spline,
 and wherein a pressing means is fixedly secured to the inner circumference
 of the rear side of the plunger to press the elastic means and move the
 over-running clutch toward the ring gear via the elastic means, the
 transmission means and the thrust spline, the pressing means being further
 arranged to cause the pinion to mesh with the ring gear by the elastic
 force of the elastic means when the top and bottom of the pinion agree
 those of the ring gear after the end surface of the pinion contacts the
 end surface of the ring gear.
 A contact shaft moving means is provided to move the contact shaft in such
 a direction as to cause the movable contact to contact the stationary
 contact after the plunger is attracted and moved for a certain time by the
 exciting coil.
 The above and other objects, features and advantages of the present
 invention will become more apparent from the following description when
 taken in conjunction with the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 [First Embodiment]
 A first embodiment of a starter of the present invention will be described
 below referring to the attached drawings.
 FIG. 1 is a sectional view showing the structure of a starter in the
 embodiment 1.
 The starter in the first embodiment is covered by such outer wall members
 as a front bracket 20, a central bracket 30, and a rear bracket 40 and
 presents a nearly bullet-shaped external appearance. A portion in which a
 ring gear 50 is located is an opening.
 In the starter, there are arranged a DC motor M and an output shaft 1 that
 is driven by this DC motor M. Around the output shaft 1, a ring-shaped
 electromagnetic switch 2, an over-running clutch 3, and a plunger (a
 movable core 4) are arranged.
 In other words, the starter according to this first embodiment is a coaxial
 type starter with the electromagnetic switch 2, the over-running clutch 3
 and the plunger 4 coaxially arranged on the output shaft 1.
 The structure of the starter according to this first embodiment will be
 described below in detail.
 In FIG. 1, the left side portion is a DC motor portion X, the right side
 portion is an operating portion Y and the upper side of the central
 portion is a contact chamber Z. The electric motor side in FIG. 1 is
 referred to as the rear and the ring gear side is referred to as the front
 in the following explanation.
 As is well known, the DC motor M comprises an armature 12, a yoke 13 that
 covers this armature 12, a stationary magnetic pole 13a provided inside
 this yoke 13, a commutator 14, brushes 15 and a shaft 16. The armature 12
 is an armature core with an armature coil wound round it. The front side
 of the shaft 16 penetrates the cylindrical space of the cylindrical
 commutator 14 and is connected to a reduction mechanism 18.
 The armature coil is connected to the commutator 14. The DC motor M is
 available in 2-pole, 4-pole and 6-pole types depending on the number of
 stationary magnetic poles. For instance, taking the case of using a 6-pole
 DC motor as a sample, a total of 6 units of the stationary magnetic pole
 13a are provided by arranging a N-pole and a S-pole alternately. The
 brushes 15 kept in contact with the commutator 14 are arranged along the
 circumference of the commutator 14.
 15a is a spring that pushes the brush 15 against the commutator 14. 15h is
 a brush holder.
 The output shaft 1 is driven by the DC motor M as described above.
 The operating portion Y comprises the reduction mechanism 18, the output
 shaft 1, the electromagnetic switch 2, the overrunning clutch 3, and the
 plunger 4.
 17 is an inner gear member. This member comprises a first tubular portion
 17a which is fitted to the outer circumference of the output shaft 1 via a
 bearing ly, a hollow disk shape bottom plate portion 17b which extends in
 the direction perpendicular to the outer circumference of the output shaft
 1 from the first tubular portion 17a, and a second tubular portion 17c
 that has an inner gear 18c on the inner circumference.
 The reduction mechanism 18 comprises the inner gear 18c of the inner gear
 member 17, a sun gear 18a provided on the shaft 16, a plurality of planet
 gears 18b arranged around this sun gear 18a engaging with the sun gear 18a
 and the inner gear 18c, and a pin 1P that projects from a flange 1F of the
 output shaft 1 inserted between the group of planet gears 18b and a bottom
 plate 17b of the inner gear member 17 and connects each of the planet
 gears 18b to the flange 1F of the output shaft 1. Further, the rotational
 force of each planet gear 18b is transmitted to each pin 1P via a bearing
 1z.
 A round groove 1h is formed at the center of the flange 1F of the output
 shaft 1 and the forward end of the shaft 16 is supported rotatably via a
 bearing 1x provided in the round groove 1h.
 Accordingly, as shown in the sectional view in FIG. 3, when the planet
 gears 18b move round the sun gear 18a, the rotational force of the shaft
 16 is reduced and transmitted to the output shaft 1 through the pins 1P.
 A helical spline 1a is formed on a part of the outer circumference at the
 central side of the output shaft 1. On the outer circumference of the part
 where this helical spline 1a is formed, the overrunning clutch 3 is
 arranged so that a tubular portion 3a of a thrust spline 3A corresponds
 thereto. Further, on the inner surface of the tubular portion 3a of the
 thrust spline 3A, ahelical spline 3x is formed to mesh with the helical
 spline 1a. That is, the overrunning clutch 3 is spline-connected to the
 output shaft 1.
 The electromagnetic switch 2 is arranged on the outer circumference of the
 tubular portion 3a of the thrust spline 3A.
 The plunger 4 is arranged on the outer circumference at the flange 1F side
 of the output shaft 1.
 The over-running clutch 3 comprises the thrust spline 3A that is formed of
 the tubular portion 3a having the helical spline 3x formed on the inner
 surface for meshing with the helical spline 1a that is formed on a part of
 the outer circumference at the central side of the output shaft 1, the
 flange portion 3b that is provided at the front side of this tubular
 portion 3a and becomes the cam bottom of a roller cam that is described
 later, a roller cam 3c interposed between the flange portion 3b of this
 thrust spline 3A and a washer 3e, a pinion 3P, an inner clutch 3y composed
 of a tubular portion at the base of the pinion 3P, a clutch roller 3r and
 a spring 3s that are arranged in a groove 3t formed on the roller cam 3c,
 and a clutch cover 3w that covers the outside of the flange portion 3b of
 the thrust spline 3A, the roller cam 3c and the washer 3e.
 The thrust spline 3A and the roller cam 3c comprise an outer clutch 3B.
 The over-running clutch 3 acts as a so-called one-way clutch. The sectional
 view of the over-running clutch is shown in FIG. 4. At several points on
 the inner circumference of the roller cam 3c, grooves 3t are provided to
 form a narrow space and a wide space between the outer circumference of
 the inner clutch 3y. The clutch roller 3r is arranged in each of these
 grooves 3t. 3s is a spring for pressing the clutch roller 3r toward the
 narrow space of the groove 3t.
 When the output shaft 1 is driven by the DC motor M, the roller cam 3c is
 rotated, the clutch roller 3r moves to the narrow space of the groove 3t,
 the roller cam 3c of the outer clutch 3B meshes with the inner clutch 3y,
 and the pinion 3P turns and meshes with the ring gear 50. Then, when the
 pinion 3P is rotated together with the ring gear 50, the clutch roller 3r
 moves to the wide space of the groove 3t, the outer clutch 3B and the
 inner clutch 3y are disengaged, and the over-running clutch 3 protects the
 power transmitted from the engine.
 The electromagnetic switch 2 comprises the exciting coil 2a, a switch case
 for covering the exciting coil 2a and a core 2c, and is arranged at the
 rear side of the position of the over-running clutch 3. The core 2c has a
 hollow shaped disc surface opposing the flange portion 3b of the thrust
 spline 3A and is made in the ring shaped body arranged so as to penetrate
 the outer circumference of the tubular portion 3a of the thrust spline 3A.
 The core 2c also has a ring shaped projecting portion 2t that extends to
 the rear side at the tubular portion 3a side of the thrust spline 3A.
 The plunger 4 is made of a tubular body that is arranged in a movable
 manner between the inner circumference of the switch case 2b and the
 tubular portion 3a of the thrust spline 3A. The front end 4t opposing the
 ring shaped projecting portion 2t is formed in a shape corresponding to
 the shape of the ring shaped projecting portion 2t.
 A ring shape plate 5a is secured on the inner circumference at the rear end
 side of the plunger 4.
 In addition, a ring shape plate 5b is also provided on the rear end side of
 the tubular portion 3a of the thrust spline 3A of the over-running clutch
 3.
 Between these plates 5a, 5b, a coil spring 6 is arranged as an elastic
 means.
 That is, the plates 5a, 5b and the coil spring 6 are provided between the
 inner circumference of the plunger 4 and the outer circumference of the
 output shaft 1.
 The plate 5b as the transmission means is kept in contact with the rear end
 3f of the thrust spline 3A and transmits the elastic force of the coil
 spring 6 to the thrust spline 3A.
 The ring-shaped plate 5a compresses the coil spring 6 and moves the
 over-running clutch 3 toward the ring gear 50 via this coil spring 6, the
 plate 5b and the thrust spline 3A, and when the gear threads and grooves
 of the pinion 3P agree with those of the ring gear 50 after the end
 surface of the pinion 3P is brought into contact with the end surface of
 the ring gear 50, meshes the pinion 3P with the ring gear 50 by the
 elastic force of the coil spring 6.
 Accordingly, the plunger 4 is attracted by the core 2c and moves in the
 direction (forward) of the core 2c and the over-running clutch moves as
 pushed by the plate 5b with the movement of the plunger 4. When the pinion
 3P once stops moving after the end surface of the pinion 3P is brought
 into contact with the end surface of the ring gear 50, the motor is driven
 and the gear threads fit the grooves of the pinion 3P. The pinion 3P
 meshes with the ring gear 50 by the elastic force of the coil spring 6
 that is compressed and accumulated up to this point. 8 is a contact shaft
 supported in a movable manner in the extended direction of the shaft by a
 supporting hole 17h provided on a part (the upper part in FIG. 1) of a
 second tubular portion 17c of the inner gear member 17. Further, the
 contact shaft 8 is mounted so as to extend over the operating portion Y
 and the contact chamber Z via the supporting hole 17h.
 At the one end side in the contact chamber Z of the contact shaft 8, a
 movable contact 8e is provided. At the rear side from this movable contact
 8e, a ring shape plate 9a is secured to the contact shaft 8. Between this
 plate 9a and the movable contact 8e, there is provided a coil spring 9b
 for pressing the movable contact 8e to the stationary contact side (later
 described). At the other end of the shaft positioned at the operation
 position Y side of the contact shaft 8, a ring shape plate 9c is secured
 to the contact shaft 8. Between this plate 9c and a front bracket 20, a
 return coil spring 9d is provided.
 A shift plate 7 is mounted on the rear end of the plunger 4. This shift
 plate 7 is a slender plate extending in the upper and lower directions
 with a hole formed at the center for mounting on the rear end of the
 plunger 4 and a through hole 7s at the upper portion corresponding to the
 contact shaft 8. This shift plate 7 is secured to the plunger 4 with an
 engaging ring 7t. Further, a return coil spring 9v is provided between the
 lower part of the shift plate 7 and the front bracket 20.
 The shift plate 7 secured to the plunger 4 and the plate 9c which is a
 plate contacting portion comprise a contact shaft moving means.
 The motor portion X, the contact chamber Z and the operating portion Y are
 divided by parting plates 34, 35.
 The contact chamber Z is divided into a contact chamber wall 31 and a
 contact chamber cover 32. A first stationary contact 10a and a second
 stationary contact 10b are provided on the contact chamber wall 31.
 The first stationary contact 10a is connected to a battery via a terminal
 volt 11. The second stationary contact 10b is connected to the positive
 pole brushes via a lead wire and is also connected to the other end of the
 exciting coil 2a of the electromagnetic switch 2.
 The terminal bolt 11 is secured with a nut 11a and the first stationary
 contact 10a is secured to the contact chamber wall 31 by a bolt head 11t.
 33 is an O-ring and 70b, 70c are packing. 70a is a grommet that is made of
 rubber or the like as a buffer material, and the contact chamber cover 32
 is pressed toward the contact chamber wall 31 by the yoke 13 via this
 grommet 70a.
 A rear end 16e of the shaft 16 is supported rotatably on a rear bracket 40
 via a bearing 60a. A front end lt of the output shaft 1 is supported on
 the side of an end 20t of the front bracket 20 via a bearing 60e.
 At the front side of the output shaft 1, a stopper 52 is provided via an
 engaging ring 51. Also, at the end of the pinion 3P, a stopper 53 is
 provided. Between these stoppers 52, 53, a return coil spring 54 is
 provided.
 41 is a bolt for securing the DC motor portion X and the operating portion
 Y by interposing them between the rear bracket 40 and the front bracket
 20.
 FIG. 5 is a perspective view of the output shaft 1, FIG. 6(a) and (b) show
 perspective views of the over-running clutch 3, and FIG. 7 shows a
 perspective view of the plunger 4 and the shift plate 7.
 Next, the operation will be described.
 When the ignition switch is turned ON and current flows to the exciting
 coil 2a of the electromagnetic switch 2, the plunger 4 is attracted toward
 the exciting core 2c, the plate 5a pushes the coil spring 6, the plate 5b
 presses the thrust spline 3A, and the over-running clutch 3 is pushed out
 toward the ring gear 50 as shown in FIG. 2. As a result, the end surface
 3Pe of the pinion 3P provided at the over-running clutch 3 is brought into
 contact with the end surface 50e of the ring gear 50 and the over-running
 clutch 3 initially stops to move in the forward direction. However, while
 the plate 5a provided at the inner circumference side of the plunger 4
 compresses the coil spring 6, the plunger is further attracted and moves
 continuously. The shift plate 7 also moves forward and contacts the plate
 9c. Further, FIG. 2 shows the state of the shift plate 7 at the moment
 when it contacts the plate 9c.
 After the state shown in FIG. 2, the plunger 4 is continuously attracted
 and the plate 9c secured to the contact shaft 8 is pushed by the shift
 plate 7 so that the contact shaft 8 also moves forward. Then, when the
 movable contact 8e of the contact shaft 8 is brought into contact with the
 first and the second stationary contacts 10a, 10b, electric power is
 supplied from a battery and the armature 12 begins to rotate.
 The contact shaft 8 moves continuously until the plunger 4 is completely
 attracted and its side of the end 4t is brought into contact with the
 exciting core 2c. At this time, the coil spring 9b is compressed by the
 plate 9a and thus, the movable contact 8e is pressed and kept in contact
 with the first and the second stationary contacts 10a, 10b.
 When the armature 12 begins to rotate, its rotational force is decelerated
 via the reduction mechanism 18 and is transmitted to the output shaft 1,
 the over-running clutch 3 that is spline connected to the output shaft
 and, further, to the pinion 3P. Then, when the pinion 3P turns slowly and
 the threads and grooves of the pinion 3P agree with those of the ring
 gear, the pinion 3P is pushed forward by the spring force (the elastic
 force) of the compressed coil spring 6 and completely meshes with the ring
 gear 50. Thus, as the crankshaft connected the ring gear turns, the engine
 is started.
 When the engine is started, the output shaft 1 and the pinion 3P are
 separated by the action of the over-running clutch 3 and the pinion 3P
 runs idle. Then, when the power supply to the exciting coil 2a is stopped,
 the pinion 3P is disengaged from the ring gear 50 as the plunger 4 and the
 over-running clutch 3 are returned to their original positions by the
 return coil springs 9d, 9v.
 When the top and bottom of the pinion 3P agree with those of the ring gear
 50, the end surface 3Pe of the pinion 3P is not brought in contact with
 the end surface 50e of the ring gear 50 but the pinion 3P meshes with the
 ring gear without any problem.
 According to the first embodiment, before the armature 12 is rotated, the
 end surface 3Pe of the pinion 3P is kept in contact with the end surface
 50e of the ring gear 50 by the elastic force of the coil spring 6 and then
 the armature 12 is rotated and the pinion 3P is meshed with the ring gear
 50 by the elastic force of the coil spring. Therefore, the pinion 3P is no
 longer repelled.
 Accordingly, when meshing with the ring gear 50, the pinion 3P can be
 smoothly engaged with the ring gear 50 without being repelled and trying
 to mesh again with the ring gear 50, and they can mesh smoothly.
 Therefore, reliability when meshing the pinion 3P and the ring gear 50
 becomes excellent so that abrasion of the gears can be reduced and the
 life span of the gears can be extended.
 Because the amount of movement of the contact shaft 8 is reduced less than
 that of the plunger 4, it becomes possible to make the contact chamber Z
 small. In other words, a starter can be provided small-sized.
 That is, in the case of a structure wherein the contact shaft moves in the
 same amount as the plunger as in a conventional starter, when the armature
 is rotated after maintaining the pinion in contact with the ring gear as
 in the embodiment 1, a large space must be provided between the movable
 contact and the stationary contact. Also, when considering the moving
 space for the plate (an engaging ring, etc.) required for holding a spring
 compressing the movable contact, the contact chamber inevitably becomes
 large in the structure of a conventional starter.
 According to the starter with the structure in this first embodiment, in
 addition to the effects as described above, the amount of motion of the
 contact shaft 8 can be reduced, the contact chamber Z can be made small,
 and as a result, a small-sized starter can be provided.
 In the first embodiment, after the plunger 4 is attracted and moved by the
 contact shaft moving means (the shift plate 7, the plate 9) for a certain
 time, the contact shaft 8 is moved in the direction to bring the movable
 contact 8e into contact with the stationary contacts 10a, 10b. However,
 the shift plate 7 may be directly connected to the contact shaft 8 so that
 the contact shaft 8 is moved together with the plunger 4. In this case,
 the plates 5a, 5b and the coil spring 6 are provided between the inner
 circumference of the plunger 4and the outer circumference of the output
 shaft 1 so as to keep the pinion 3P in contact with the ring gear 50 and
 therefore, when meshing with the ring gear 50, the pinion 3P will no
 longer be repelled and try again to mesh. Thus, the pinion P3 can mesh
 with the ring gear 50 more smoothly than before. Therefore, reliability
 when meshing the pinion 3P with the ring gear 50 becomes excellent,
 abrasion of the gears is reduced and the life span of the gears can be
 extended.
 The various springs described above may be made of rubber. In short,
 elastic means capable of conserving elastic force are acceptable.
 In the first embodiment, the contact shaft 8 is supported by the supporting
 hole 17h provided on the inner gear member 17. A supporting portion with a
 supporting hole formed for supporting the contact shaft 8 may be provided
 on a center bracket 30, which is an outer wall member, and the contact
 shaft 8 may be supported by the center bracket 30.
 A tubular body 5 shown in FIG. 8 may be used instead of the plate 5b.
 In this case, a first engaging portion 4x projecting toward the output
 shaft 1 is to be formed on the end 4t of the plunger 4 and a second
 engaging portion 5x that engages the first engaging portion 4x is to be
 formed at the other end of the tubular body 5. Then, the tubular body 5 is
 provided in the state wherein its one end 5f is maintained in contact with
 one end 3f of the thrust spline 3A and the other end is kept engaged with
 the first engaging portion 4x by the second engaging portion 5x.
 The over-running clutch 3 is arranged so that the rear end 3f of the
 tubular portion 3a of the thrust spline 3A is positioned at a specified
 space between the exciting core 2c and the end 4t of the opposing plunger
 4.
 A tubular body made of non-magnetic or low permeability material is used
 for the tubular body 5 to cover the outer circumference of the output
 shaft 1 corresponding to the specified space g. Thus, when the exciting
 coil 2a is excited, magnetic flux that leaks to the output shaft 1 and the
 thrust spline 3a can be reduced and the attracting force to the plunger 4
 can be improved.
 According to the present invention, the elastic means, the transmission
 means and the pressing means are provided between the inner circumference
 of the plunger and the outer circumference of the output shaft and it is
 therefore possible to obtain a starter capable of meshing the pinion with
 the ring gear more smoothly than before, giving excellent reliability when
 meshing the pinion with the ring gear, reducing abrasion of the gears and
 extending the life span of the gears.
 In addition, the contact shaft moving means provided makes it possible to
 mesh the pinion with the ring gear more smoothly and further, to provide a
 small-sized starter.
 The movable contact of the contact shaft is brought into contact with the
 stationary contact by the action of the contact shaft moving means after
 the end surface of the pinion has contacted the end surface of the ring
 gear, the pinion is no longer repelled when meshing with the ring gear and
 try to again mesh, and the effects described above can be further
 improved.