JP2008095594A - Starter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a starter capable of reducing an excessive shock without increase in the size of an shock absorbing device. <P>SOLUTION: The shock absorbing device is composed of a front side case 37 connected to a cylindrical part (a pinion cylindrical part) integrally provided with a pinion gear, a rear side case connected to an output shaft, an intermediate case arranged between the two cases, a plurality of shock absorbing members built in between the cases and the like. The front side case 37 is provided with a first projecting part 37a for regulating the compression ratio of the shock absorbing member 40 between the front side case 37 and the intermediate case 39, and a hollow part 37c is formed in the first projecting part 37a. A section modulus can be reduced in the first projecting part 37a having the hollow part 37c comparing with a projecting part with no hollow part. As a result, torsional stiffness of the front side case 37 or the torsional stiffness of the starter can be reduced, and the shock (excessive shock) generated due to an input of excessive torque can be reduced. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a starter provided with an impact absorbing device that reduces an impact generated when an engine is started.

2. Description of the Related Art Conventionally, in a general internal combustion engine (for example, a four-cycle engine) mounted on many vehicles, the load fluctuates abruptly depending on each step of the piston, and the rotation speed also pulsates.
However, since the starter that starts the engine cannot skillfully follow the engine load fluctuation, a relative speed difference occurs between the ring gear on the engine side and the pinion gear of the starter, and the phenomenon that the pinion gear hits the ring gear occurs.
In other words, while the piston moves from the bottom dead center to the top dead center, the pinion gear constantly presses the ring gear, but when the piston passes the top dead center, the engine rotation is accelerated, so the pinion gear is used to rotate the ring gear. Can not go, finally the pinion gear is separated from the ring gear. After that, when passing through the bottom dead center and approaching the top dead center, the pinion gear catches up with the ring gear and collides. At this time, a phenomenon in which the pinion gear hits the ring gear occurs, and a hitting sound is generated with an impact. Further, at the beginning of engine starting, the pinion gear meshes with the stationary ring gear while rotating, so that the relative speed difference between the two becomes large, and an excessive impact torque and meshing noise are generated.

In order to design the starter components that can withstand the above-mentioned impacts, the strength of the strength components and the physique increase are required, which leads to an increase in cost and deterioration in mountability to the engine. Further, a hitting sound generated when the pinion gear hits the ring gear, a meshing sound generated when the pinion gear meshes with the ring gear in a stationary state, and the like are uncomfortable for the user.
Therefore, a starter in which an impact absorbing device is arranged between the output shaft and the pinion gear is known as means for reducing the impact, unpleasant hitting sound and meshing sound generated at the time of starting the engine (see Patent Document 1).

The shock absorbing device includes a first case that engages with the pinion gear so as not to rotate relative to the pinion gear, a second case that engages with the output shaft so as not to rotate relative to the output shaft, and a buffer member such as rubber disposed between the two cases. Both cases configured to accommodate the buffer member are provided with stopper portions for regulating the compression rate of the buffer member.
Note that at least one intermediate case may be disposed between the first case and the second case, and the buffer members may be disposed in series in multiple stages via the intermediate case. For example, if the number of intermediate cases is one, buffer members may be arranged between the first case and the intermediate case and between the intermediate case and the second case.

The stopper portion is constituted by, for example, a protrusion provided on the first case and a protrusion provided on the second case, and an overload (for example, engine misignition, reverse explosion, always-engaged starter in a constant mesh starter, etc.) When the shock absorbing member is compressed by a predetermined compression ratio, the protrusions of both cases come into contact with each other to prevent the shock absorbing member from being further compressed. .
On the other hand, for input of a light load (for example, cranking impact at start-up), the protrusions of both cases do not come into contact with each other, and the generated impact can be reduced by utilizing the elasticity of the buffer member. .
JP 2006-207573 A

Since the impact torque generated in the starter is proportional to the square root of the torsional rigidity (spring constant) of the starter, as shown by the following formula, the impact torque can be reduced by reducing the torsional rigidity of the starter.

Further, the torsional rigidity of the starter after the abutting wall comes into contact with the stopper wall affects the torsional rigidity of the case including the stopper portion (protrusion) regardless of the spring constant of the buffer member. Therefore, reducing the torsional rigidity of the case leads to a reduction in excessive impact.
However, when the torsional rigidity of the case is reduced, there is a problem of insufficient strength at the engaging portion between the first case and the pinion gear and the engaging portion between the second case and the output shaft. That is, since the torque is transmitted at the engaging portion between the first case and the pinion gear and the engaging portion between the second case and the output shaft, it is necessary to ensure sufficient strength to satisfy the necessary transmission torque. There is. For example, in the case of a serration fitting structure, it is possible to secure the strength of the coupling portion by a method such as increasing the length of the serration, increasing the number of teeth, or increasing the module. However, both methods lead to an increase in the size of the engaging portion.

On the other hand, the strength of the joint can be increased without increasing the physique by using a high strength material (for example, iron) or a heat-treated metal material for the case as compared to resin or aluminum. Can be secured.
However, in general, when a high-strength material is used, the longitudinal elastic modulus of the material also increases, and as a result, the torsional rigidity also increases. Therefore, “In order to reduce the excessive impact, the torsional rigidity of the case is reduced. The initial purpose of “decrease” cannot be achieved.
The present invention has been made based on the above circumstances, and an object of the present invention is to provide a starter capable of reducing an impact (excessive impact) caused by an input of an excessive load without accompanying the build-up of the impact absorbing device. is there.

(Invention of Claim 1)
The starter of the present invention is disposed on a motor that generates a rotational force, an output shaft that rotates by transmission of a driving torque of the motor, and a relative rotation on the output shaft, and meshes with a ring gear on the engine side. The motor includes a pinion gear that transmits the driving torque of the motor to the ring gear, and an impact absorbing device that is provided between the output shaft and the pinion gear and reduces an impact that occurs during torque transmission.
The shock absorbing device is disposed between the first case that engages with the pinion gear in a relatively non-rotatable manner, the second case that engages with the output shaft in a relatively non-rotatable manner, and the first case and the second case. And a shock-absorbing member that compresses and deforms when a relative rotation occurs between the first case and the second case due to an impact during torque transmission. The first case and the second case are: When the buffer member is compressed and deformed with the relative rotation of the two cases, it has a stopper portion that restricts the compression rate, and a hollow portion is formed in the stopper portion.

According to the above configuration, when the buffer member is compressed to a compression rate regulated in advance by the input of an excessive load, i.e., when the stopper portion comes into contact, the stopper portion is not related to the spring constant of the buffer member. The torsional rigidity of the included cases (first case and second case) greatly affects the torsional rigidity (spring constant) of the starter.
Here, by forming the hollow portion in the stopper portion of the case, the section modulus of the stopper portion can be reduced as compared with the stopper portion having no hollow portion. As a result, the torsional rigidity of the case, that is, the torsional rigidity of the starter can be reduced, so that an impact (excessive impact) caused by an input of an excessive load can be reduced.
Further, by forming the hollow portion in the stopper portion, the mass of the case can be reduced, and the inertia of the case can be reduced. Therefore, an impact reduction effect by reducing the moment of inertia can be expected.

(Invention of Claim 2)
The starter according to claim 1, wherein both the first case and the second case are made of metal.
In this case, since the engaging part of the first case that engages with the pinion gear in a relatively non-rotatable manner and the engaging part of the second case that engages with the output shaft in a relatively non-rotatable manner are both made of metal, The strength sufficient to satisfy the required transmission torque can be ensured without increasing the size of the engaging portion.

(Invention of Claim 3)
The starter of the present invention is disposed on a motor that generates a rotational force, an output shaft that rotates by transmission of a driving torque of the motor, and a relative rotation on the output shaft, and meshes with a ring gear on the engine side. The motor includes a pinion gear that transmits the driving torque of the motor to the ring gear, and an impact absorbing device that is provided between the output shaft and the pinion gear and reduces an impact that occurs during torque transmission.
The shock absorbing device is disposed between the first case that engages with the pinion gear in a relatively non-rotatable manner, the second case that engages with the output shaft in a relatively non-rotatable manner, and the first case and the second case. And a shock-absorbing member that compresses and deforms when a relative rotation occurs between the first case and the second case due to an impact during torque transmission. The first case and the second case are: When the buffer member is compressed and deformed with the relative rotation of the two cases, the first stopper member has a stopper portion that restricts the compression rate, and the stopper portion is made of resin and engages with the pinion gear so as not to rotate relatively. Both the engaging portion of the case and the engaging portion of the second case that engages with the output shaft so as not to rotate relative to each other are made of metal.

According to the above configuration, when the buffer member is compressed to a compression rate regulated in advance by the input of an excessive load, i.e., when the stopper portion comes into contact, the stopper portion is not related to the spring constant of the buffer member. The torsional rigidity of the included cases (first case and second case) greatly affects the torsional rigidity (spring constant) of the starter.
Here, the stopper part of the case is made of resin, so that the rigidity of the stopper part can be reduced as compared with the case where the stopper part is made of metal. As a result, the torsional rigidity of the case, that is, the torsional rigidity of the starter can be reduced, so that an impact (excessive impact) caused by an input of an excessive load can be reduced.
On the other hand, since the engaging part of the first case that engages with the pinion gear in a relatively non-rotatable manner and the engaging part of the second case that engages with the output shaft in a relatively non-rotatable manner are both made of metal, Ensuring sufficient strength to satisfy required transmission torque. In other words, it is not necessary to increase the size of the engaging portion in order to ensure the strength, and the necessary strength can be ensured without increasing the size of the engaging portion.

(Invention of Claim 4)
The starter according to any one of claims 1 to 3, wherein the shock absorbing device has at least one intermediate case between the first case and the second case, and each of the shock absorbers is provided between the cases. The intermediate case is provided with a stopper portion that regulates the compression rate of the buffer member between the first case and the second case, or between the intermediate cases. It is characterized by that.
In this case, the shock absorbing capability can be improved without increasing the outer diameter of the shock absorbing device by arranging the buffer members in series in multiple stages via the intermediate case.
Note that one or two or more intermediate cases may be used.

(Invention of Claim 5)
The starter described in claim 4 is characterized in that a hollow portion is formed in a stopper portion provided in the intermediate case.
Similarly to the invention according to claim 1, by forming the hollow portion in the stopper portion of the intermediate case, the section modulus of the stopper portion can be reduced as compared with the stopper portion having no hollow portion. As a result, the torsional rigidity of the entire case including the intermediate case, that is, the torsional rigidity of the starter can be reduced, so that excessive impact can be reduced.
Further, by forming a hollow portion in the stopper portion of the intermediate case, the mass of the entire case can be reduced, and the inertia of the case can be reduced. Therefore, an impact reduction effect by reducing the moment of inertia can be expected.

(Invention of Claim 6)
The starter described in claim 4 is characterized in that the intermediate case is made of resin.
By making the intermediate case made of resin, the torsional rigidity of the intermediate case can be reduced as compared with a metal intermediate case. As a result, the torsional rigidity of the entire case including the intermediate case, that is, the torsional rigidity of the starter can be reduced, so that excessive impact can be reduced.

(Invention of Claim 7)
The starter according to any one of claims 1 to 6, further comprising a torque limiter provided in a torque transmission path between the motor and the output shaft, the torque limiter having a rotating plate whose rotation is restricted by a frictional force. When an excessive torque exceeding the sliding torque of the rotating plate is applied to the rotating plate, the rotating plate slides against the frictional force (rotates), thereby interrupting the transmission of the excessive torque.
In the friction type torque limiter, when an excessive torque exceeding a certain set torque is applied, the rotary plate is slid to cut the excessive torque. The overshoot (peak value) exceeding the set torque occurs. This peak value is due to the speed responsiveness of the torque limiter. By reducing the spring constant in the torque transmission path from the pinion gear, which is the source of impact, to the torque limiter, and by reducing the impact transmission speed, the torque limiter Speed responsiveness can be improved. Therefore, the starter of the present invention can keep the peak value low by improving the speed responsiveness of the torque limiter as compared with the conventional starter having the torque limiter.

(Invention of Claim 8)
The starter according to any one of claims 1 to 7, wherein the starter is used in an engine automatic stop / restart system that automatically controls stop and restart of the engine.
An automatic engine stop / restart system (also called idle stop, eco-run system, etc.), for example, when the vehicle is temporarily stopped at an intersection or traffic jam, the engine is automatically stopped, and then a predetermined start operation is performed. The engine is automatically restarted, which is effective for improving the fuel efficiency of the vehicle or improving the exhaust emission.
In a vehicle equipped with this automatic engine stop / restart system, the number of engine starts, that is, the number of starter starts inevitably increases compared to a vehicle not equipped with the system.

By the way, when the engine is started, noise unpleasant for the user (engagement sound when the pinion gear meshes with the ring gear and tapping sound when the pinion gear strikes the ring gear) is generated along with the impact. For this reason, in a vehicle equipped with the above system, unpleasant noise and impact are generated each time the engine is restarted.
On the other hand, since the starter of the present invention can reduce the impact and unpleasant noise generated at the time of engine start by the shock absorbing device, it can be suitably used for an engine automatic stop / restart system having a large number of starts. Discomfort can be reduced.

  The best mode for carrying out the present invention will be described in detail with reference to the following examples.

FIG. 1 is a half sectional view of the starter 1.
As shown in FIG. 1, the starter 1 according to the first embodiment includes a motor 2 that generates rotational force, an electromagnetic relay 3 that opens and closes a main contact (described later) provided in the motor circuit, and prevents the motor 2 from rotating backward. The reverse rotation preventing clutch 4, the speed reducer 5 that amplifies the drive torque of the motor 2, the output shaft 6 to which the drive torque of the motor 2 is transmitted via the speed reducer 5, and the output shaft 6. Pinion gear 7 and an impact absorbing device 8 that absorbs an impact generated when the engine is started.
The starter 1 can be used in an engine automatic stop / restart system that automatically controls engine stop and restart. The system automatically stops the engine when, for example, the vehicle stops at a signal stop or traffic jam at an intersection, and then responds to a predetermined start operation (for example, when the driver releases the brake pedal). This system automatically restarts the engine.

The motor 2 includes a cylindrical yoke 9 that forms a magnetic circuit, a plurality of permanent magnets 10 (may be field coils) disposed on the inner periphery of the yoke 9, and a gap formed on the inner periphery of the permanent magnet 10. It is a well-known direct current motor constituted by an armature 11 or the like that is rotatably disposed.
The armature 11 is connected to an armature core 13 that is serrated and fitted to the outer periphery of the armature shaft 12, an armature coil 14 wound around the armature core 13, and the armature coil 14. A battery current is supplied to the armature coil 14 through a brush 16 that has a commutator 15 and is in sliding contact with the commutator 15.
The motor 2 is assembled by fitting the front end of the yoke 9 into the opening of the housing 17, and the end frame 18 is fitted to the rear end opening of the yoke 9 to cover the rear of the armature 11. The plurality of through bolts 19 are passed from the rear of the end frame 18, and the through bolts 19 are fastened to the housing 17.

  The electromagnetic relay 3 includes an electromagnetic coil (not shown) that is energized from a battery to form an electromagnet, and a plunger 20 that is movable facing the electromagnet. When the electromagnet is formed by energizing the electromagnetic coil, When the plunger 20 is attracted and moved by the electromagnet, the main contact of the motor circuit is closed in conjunction with the movement of the plunger 20. When energization of the electromagnetic coil is stopped and the attraction force of the electromagnet disappears, the plunger 20 is pushed back by the reaction force of a return spring (not shown) to open the main contact.

The main contact is moved together with the plunger 20 to connect and disconnect between a set of fixed contacts (not shown) connected to the motor circuit via the two external terminals 21 and 22. It is formed with a movable contact (not shown), the movable contact abuts on a set of fixed contacts, and between the fixed contacts becomes conductive, the main contact is closed, and the movable contact is separated from the set of fixed contacts. As a result, the main contact is closed by disconnecting the conduction between the two fixed contacts.
The two external terminals 21 and 22 are a B terminal 21 connected to a battery via a battery cable and an M terminal 22 to which a motor lead wire 23 taken out from the motor 2 is connected. Resin of the electromagnetic relay 3 It is fixed to the cover 3a. The motor lead wire 23 is held by a grommet 24 sandwiched between the yoke 9 and the end frame 18, and is connected to the positive brush 16 inside the motor 2.

The reverse rotation prevention clutch (hereinafter referred to as the clutch 4) is disposed concentrically with the inner 25 provided on the armature shaft 12, and forms a plurality of cam chambers (not shown) on the outer periphery of the inner 25. The outer 26 and the roller 27 disposed in the cam chamber are configured.
The inner 25 is provided in a cylindrical shape, is fitted and fixed to the outer periphery of the armature shaft 12 by press fitting or the like, and rotates integrally with the armature shaft 12.
The outer 26 has an outer wall portion 26a coupled to its outer diameter portion so as not to be relatively rotatable, and an outer peripheral portion of the outer wall portion 26a is sandwiched between the spacer member 28 and the yoke 9 in the axial direction. While being positioned, an engaging portion (not shown) provided on the outer periphery of the outer wall portion 26 a is engaged with the inner periphery of the housing 17 and is restricted in rotation.
The roller 27 is urged in a narrow direction of the cam chamber by a spring (not shown), and has a function of intermittently transmitting torque between the inner 25 and the outer 26.

When the engine rotates reversely (for example, when the engine is stopped, the crankshaft swings, or when the vehicle retreats due to an uphill road stall), the reverse rotation of the clutch 4 is transmitted. The armature 11 has a function of preventing reverse rotation of the armature 11 so as not to reversely rotate. That is, when the reverse rotation of the engine is transmitted to the armature shaft 12 via the speed reducer 5, the roller 27 is locked between the outer peripheral surface of the inner 25 and the inner peripheral surface of the cam chamber, and the rotation of the inner 25 is performed. That is, reverse rotation of the armature shaft 12 is prevented. As a result, it is possible to prevent the armature 11 from rotating in the direction opposite to that when starting the engine.
On the other hand, when the engine is started, the roller 27 idles between the outer peripheral surface of the inner 25 and the inner peripheral surface of the cam chamber, thereby allowing the armature shaft 12 to rotate.

The speed reducer 5 includes a sun gear 29 formed on the armature shaft 12, an internal gear 30 that is rotationally restricted via a slip type torque limiter described below, and a plurality of planetary gears 31 that mesh with both gears 29, 30. Is a well-known planetary gear reducer, and is configured on the anti-iron core side (the left side in the drawing) of the clutch 4.
The torque limiter has a rotating disk 33 (rotary plate of the present invention) whose rotation is restricted by a frictional force with respect to the center case 32, and when an excessive torque exceeding the sliding torque of the rotating disk 33 is applied to the internal gear 30, When the rotating disk 33 slides (rotates) against the frictional force, the internal gear 30 is allowed to rotate and absorbs excessive torque.

The center case 32 is disposed inside the housing 17 so as to be orthogonal to the output shaft 6, abuts against a step provided on the inner periphery of the housing 17, is positioned in the axial direction, and is restricted in rotation with respect to the housing 17. Yes.
The output shaft 6 is disposed coaxially with the armature shaft 12, and the end on the side opposite to the motor is rotatably supported by the tip of the housing 17 via the bearing 34, and the end on the motor 2 side is decelerated. It is connected to the armature shaft 12 via the machine 5 and is rotatably supported by the center case 32. The pinion gear 7 is fitted to the outer periphery of the output shaft 6 via a bearing 35 so as to be relatively rotatable, is always meshed with a ring gear 36 on the engine side, and further, the output shaft 6 is connected via an impact absorbing device 8 described below. It is connected to.

The shock absorbing device 8 includes a front case 37 (first case of the present invention) connected to a cylindrical portion (referred to as a pinion cylindrical portion 7a) provided integrally with the pinion gear 7, and a rear case connected to the output shaft 6. A side case 38 (second case of the present invention), an intermediate case 39 disposed between the cases 37 and 38, and a plurality of buffer members 40 incorporated between the cases 37 to 39, etc. The
As shown in FIG. 2, the front case 37 is provided in a substantially disc shape having a cylindrical boss portion 370, and is formed on the outer periphery of the pinion cylindrical portion 7a and the serration 371 formed on the inner periphery of the boss portion 370. Is engaged with the outer periphery of the pinion cylindrical portion 7a so as not to be relatively rotatable (see FIG. 1).

The front case 37 is provided with a first protrusion group and a second protrusion group on the rear end face facing the intermediate case 39.
As shown in FIG. 2B, the first projection group is three projection portions (referred to as first projection portions 37a) arranged at intervals of 120 degrees in the circumferential direction. These are three protrusions (referred to as second protrusions 37b) arranged at intervals of 120 degrees in the circumferential direction at positions displaced from the first protrusion group in the circumferential direction.
Between the first projecting portion 37a and the second projecting portion 37b adjacent in the circumferential direction, a space having a large space therebetween and a space having a small space are alternately formed in the circumferential direction so as to be large. The buffer member 40 is arranged in the space S.
The three first protrusions 37a and the three second protrusions 37b are each formed with a hollow part 37c (see FIG. 2A).

As shown in FIG. 3, the rear case 38 is provided in a substantially disk shape having a cylindrical boss portion 380, and is formed on the serration 381 formed on the inner periphery of the boss portion 380 and on the outer periphery of the output shaft 6. Is engaged with the outer periphery of the output shaft 6 so as not to be relatively rotatable (see FIG. 1).
The rear case 38 is provided with a first protrusion group and a second protrusion group on the front end surface facing the intermediate case 39.
The first protrusion group includes three protrusions (referred to as first protrusions 38a) arranged at intervals of 120 degrees in the circumferential direction, and the second protrusion group extends from the first protrusion group in the circumferential direction. Three protrusions (referred to as second protrusions 38b) arranged at 120 ° intervals in the circumferential direction at shifted positions.

Between the first protrusions 38a and the second protrusions 38b adjacent to each other in the circumferential direction, a space having a large space between them and a space having a small space are alternately formed in the circumferential direction. The buffer member 40 is arranged in the space S.
The three first protrusions 38a and the three second protrusions 38b each have a hollow part 38c (see FIG. 3B).
The intermediate case 39 is provided in an annular shape that is fitted to the outer periphery of the boss portion 380 provided in the rear case 38 so as to be relatively rotatable, and as shown in FIG. 4B, the front end facing the front case 37 A first protrusion group (three first protrusions 39a) and a second protrusion group (three second protrusions) are respectively formed on a surface (left surface in the drawing) and a rear end surface (right surface in the drawing) facing the rear case 38. A protrusion 39b).

As shown in FIG. 5 (a), the buffer member 40 is provided with a block-shaped main lump portion 40a and a sub lump portion 40c connected to the main lump portion 40a via a bridging portion 40b. The synthetic rubber (for example, NBR) is integrally formed. Three buffer members 40 are incorporated between the front case 37 and the intermediate case 39 and between the rear case 38 and the intermediate case 39, respectively.
Here, the arrangement of the buffer member 40 incorporated between the rear case 38 and the intermediate case 39 will be described with reference to FIG.

The buffer member 40 is disposed in a space provided between the first protrusion 38 a and the second protrusion 38 b of the rear case 38, and the second protrusion 39 b provided on the rear end surface of the intermediate case 39 is buffered. The member 40 is inserted between the main mass portion 40a and the sub mass portion 40c. As a result, the buffer member 40 has the main lump 40a sandwiched between the second protrusion 38b of the rear case 38 and the second protrusion 39b of the intermediate case 39, and the second protrusion 39b of the intermediate case 39 It is set in a state where the sub-lumb portion 40c is sandwiched between the first protrusion 38a of the rear case 38.
The arrangement of the buffer member 40 incorporated between the front case 37 and the intermediate case 39 is also substantially the same.

In addition, the rear case 38 and the intermediate case 39 have a gap G between the first protrusion 38a of the rear case 38 and the first protrusion 39a of the intermediate case 39 in a state where the buffer member 40 is incorporated. The cases 38 and 39 are combined so as to be rotatable relative to the gap. Similarly, the front case 37 and the intermediate case 39 are combined so as to be relatively rotatable by a gap secured between the cases 37 and 39 in a state in which the buffer member 40 is incorporated.
Therefore, the relative rotation angle allowed between the front case 37 and the intermediate case 39 and the rear case 38 and the intermediate case 39 are allowed between the front case 37 and the rear case 38. A relative rotation angle obtained by adding up the relative rotation angles is given.

Next, the operation of the shock absorbing device 8 will be described with reference to FIG.
For example, when the impact at the time of cranking is transmitted to the pinion gear 7, relative rotation occurs between the rear case 38 and the intermediate case 39 from the stationary state shown in FIG. The main mass portion 40a of the buffer member 40 sandwiched between the second projection portion 38b and the second projection portion 39b of the intermediate case 39 is compressed. Similarly, the main mass portion 40a of the buffer member 40 incorporated between the front case 37 and the intermediate case 39 is compressed. The compression at the time of cranking is absorbed by the compression of the buffer member 40.

Further, when the relative rotation angle between the rear case 38 and the intermediate case 39 reaches a predetermined value, in other words, when the compression rate of the buffer member 40 reaches a predetermined value (for example, 30%), FIG. As shown, the first protrusion 39a of the intermediate case 39 abuts on the first protrusion 38a of the rear case 38, thereby preventing relative rotation of the cases 38 and 39. Similarly, relative rotation between the front case 37 and the intermediate case 39 is prevented. Thereby, the buffer member 40 is not compressed exceeding the compression rate regulated in advance, and the buffer member 40 can be prevented from being damaged or broken.
The first protrusion 37a provided on the front case 37, the first protrusion 38a provided on the rear case 38, and the first protrusion 39a provided on the intermediate case 39 are respectively a stopper portion of the present invention. Is configured.

Next, the operation of the starter 1 will be described.
When the main contact of the motor circuit is closed by the electromagnetic relay 3, power is supplied from the battery to the armature 11 to generate a rotational force on the armature 11. The rotation of the armature 11 is transmitted to the output shaft 6 via the speed reducer 5 and further transmitted from the pinion gear 7 to the ring gear 36 to crank the engine. The impact generated during the cranking is absorbed by the impact absorbing device 8. In the impact absorbing device 8 of the present embodiment, the maximum torque that can be absorbed when all the buffer members 40 bend (compress) is set to be larger than the maximum cranking torque that is generated when the engine is cranked.

When the engine completes explosion and the engine speed exceeds the starter speed, for example, a one-way clutch (not shown) built in the ring gear 36 idles and the ring gear 36 is disconnected from the crankshaft of the engine. The rotation of the engine is not transmitted to the pinion gear 7, and overrun of the armature 11 can be prevented.
Further, when the engine rotates reversely due to erroneous ignition or reverse explosion of the engine, or when an excessive load torque is input to the starter 1 or the like, the buffer member 40 of the shock absorbing device 8 reaches a predetermined compression rate. After the impact is reduced by compression, the excessive impact that cannot be absorbed by the impact absorbing device 8 is cut by sliding the rotary disk 33 used in the torque limiter.

(Effect of Example 1)
In the starter 1 of this embodiment, when an excessive torque larger than the maximum cranking torque generated at the time of engine cranking is input, the shock absorbing member 40 built in the shock absorbing device 8 is compressed to a compression rate regulated in advance. Thus, the first protrusions 37a, 38a, 39a of the cases 37 to 39 constituting the stopper portion come into contact with each other, and the front case 37 and the intermediate case 39 and the rear case 38 and the intermediate case 39 are relatively rotated. Be blocked. In this case, regardless of the spring constant of the buffer member 40, the torsional rigidity of the front case 37 and the rear case 38 including the stopper portion greatly affects the torsional rigidity (spring constant) of the starter 1.
On the other hand, the shock absorbing device 8 of the present embodiment forms the hollow portions 37c, 38c in the first protrusions 37a, 38a and the second protrusions 37b, 38b provided in the front case 37 and the rear case 38, respectively. Therefore, the section modulus of the projection can be reduced as compared with the projection having no hollow portion. As a result, the torsional rigidity of the front case 37 and the rear case 38, that is, the torsional rigidity of the starter 1, can be reduced, so that the impact (excessive impact) caused by the input of excessive torque can be reduced.

  The front case 37 and the rear case 38 are both made of metal (for example, iron), the boss portion 370 of the front case 37 coupled to the pinion cylindrical portion 7a, and the rear case 38 coupled to the output shaft 6. The boss portion 380 can secure sufficient strength to satisfy the required transmission torque. In other words, it is not necessary to increase the size of the boss portions 370 and 380 by securing the strength by increasing the length of the serration, increasing the number of teeth, or increasing the module. The intermediate case 39 may be made of metal, but can be reduced in weight by being made of resin, for example.

Further, the starter 1 of the present embodiment reduces the spring constant in the torque transmission path from the pinion gear 7 that is an impact generation source to the torque limiter, and reduces the transmission speed of the impact, thereby improving the speed responsiveness of the torque limiter. Because it improves, the transmission of excessive shock can be cut off quickly.
Further, by forming hollow portions 37c, 38c in the first protrusions 37a, 38a and the second protrusions 37b, 38b of the front case 37 and the rear case 38, the mass of the front case 37 and the rear case 38 can be increased. Since it can be reduced, an impact reduction effect by reducing the moment of inertia can be expected.
Further, the front case 37 and the rear case 38 can be press-molded with the first protrusions 37a and 38a and the second protrusions 37b and 38b. For example, when the entire case is formed by cutting In comparison, the manufacturing cost can be greatly reduced, and mass production is also possible.

FIG. 6 is a half sectional view of the starter 1.
The starter 1 of the present embodiment is an example in which protrusions provided on the cases 37 to 39 of the shock absorbing device 8 are made of resin.
For example, as shown in FIG. 7, in the front case 37, the boss portion 370 coupled to the pinion cylindrical portion 7a is made of metal, and the first protruding portion 37a and the second protruding portion 37b are made of resin.
In the rear case 38, as shown in FIG. 8, the boss 380 coupled to the output shaft 6 is made of metal, and the first protrusion 38a and the second protrusion 38b are made of resin.
In the intermediate case 39, the entire case including the first protrusion 39a and the second protrusion 39b is made of resin.

According to said structure, compared with the case where 1st protrusion part 37a, 38a, 39a of each case 37-39 which comprises a stopper part is comprised with a metal, 1st protrusion part 37a, 38a, 39a is resinized. By doing so, the rigidity of the stopper portion can be reduced. As a result, the torsional rigidity of the cases 37 to 39, that is, the torsional rigidity of the starter 1 can be reduced, so that an impact (excessive impact) caused by an input of an excessive load can be reduced.
On the other hand, the boss portion 370 of the front case 37 that is serrated and fitted to the pinion cylindrical portion 7a and the boss portion 380 of the rear case 38 that is serrated and fitted to the output shaft 6 are each made of metal. It is possible to ensure sufficient strength. In other words, it is not necessary to increase the physique of the boss portions 370 and 380 by increasing the length of the serration, increasing the number of teeth, or enlarging the module in order to secure the strength. The necessary strength can be ensured without increasing the size of 380.

  In addition, the front case 37 and the rear case 38 can be formed by forming only metal parts including the boss parts 370 and 380, respectively, heat-treating the metal parts, and then insert-molding the resin parts. Thereby, since the protrusion part comprised with resin does not receive the influence of the distortion by heat processing, since the protrusion part does not deform | transform by heat processing, the intensity | strength of the boss | hub parts 370 and 380 can be improved, Therefore The size can be reduced.

(Modification)
In the above embodiment, synthetic rubber is used for the buffer member 40 of the impact absorbing device 8, but elastic bodies (for example, torsion coil springs, elastic resin materials, etc.) other than synthetic rubber can also be used.
In the first embodiment, the hollow portions 37c and 38c are formed in all the protrusions 37a, 37b, 38a, and 38b provided in the front case 37 and the rear case 38, but the protrusions that constitute the stopper portion (front case) The hollow portions 37c and 38c may be formed only in the first protrusion portion 37a of the 37 and the first protrusion portion 38a of the rear case 38). Moreover, you may form a hollow part in the 1st projection part 39a and the 2nd projection part 39b of the intermediate | middle case 39. FIG.
In the impact absorbing device 8 described in the first and second embodiments, the buffer member 40 is arranged in two stages in series via the intermediate case 39, but the number of intermediate cases 39 is increased and arranged in three or more stages in series. You may do it. Alternatively, the intermediate case 39 may be eliminated and the buffer member 40 may be disposed between the front case 37 and the rear case 38.

(Example 1) which is a half sectional view of a starter. (A) It is AA sectional drawing of a front case, (b) It is a front view of a front case. (A) Front view of rear case, (b) AA sectional view of rear case. (A) Front front view of intermediate case, (b) AA sectional view of intermediate case, (c) Rear front view of intermediate case. (A) The top view which shows the stationary state of an impact-absorbing device, (b) It is a top view which shows the operating state of an impact-absorbing device. (Example 2) which is a half sectional view of a starter. (A) It is AA sectional drawing of a front case, (b) It is a front view of a front case. (A) Front view of rear case, (b) AA sectional view of rear case.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Starter 2 Motor 6 Output shaft 7 Pinion gear 8 Shock absorber 33 Rotating disk (rotating plate)
36 Ring gear 37 Front case (first case of the present invention)
37a First protrusion of front case (stopper provided on front case)
37c Hollow portion 38 Rear case (second case of the present invention)
38a First protrusion of rear case (stopper provided on rear case)
38c Hollow portion 39 Intermediate case 40 Buffer member 370 Boss portion (engagement portion of front case engaged with pinion gear so as not to be relatively rotatable)
380 Boss part (engagement part of rear case engaged with the output shaft so as not to be relatively rotatable)

Claims (8)

A motor that generates rotational force;
An output shaft that rotates when the driving torque of the motor is transmitted;
A pinion gear that is disposed on the output shaft so as to be relatively rotatable and meshes with a ring gear on the engine side to transmit the driving torque of the motor to the ring gear;
A starter provided between the output shaft and the pinion gear and provided with an impact absorbing device for reducing an impact generated during torque transmission;
The shock absorber is
A first case that engages with the pinion gear in a relatively non-rotatable manner;
A second case engaged with the output shaft so as not to rotate relative to the output shaft;
It is arranged between the first case and the second case, and is compressed and deformed when a relative rotation occurs between the first case and the second case due to an impact during torque transmission. A buffer member,
The first case and the second case have a stopper portion that restricts the compression rate when the buffer member is compressed and deformed with relative rotation of the two cases, and a hollow portion is formed in the stopper portion. Starter characterized by being. The starter according to claim 1,
Both the first case and the second case are made of metal. A motor that generates rotational force;
An output shaft that rotates when the driving torque of the motor is transmitted;
A pinion gear that is disposed on the output shaft so as to be relatively rotatable and meshes with a ring gear on the engine side to transmit the driving torque of the motor to the ring gear;
A starter provided between the output shaft and the pinion gear and provided with an impact absorbing device for reducing an impact generated during torque transmission;
The shock absorber is
A first case that engages with the pinion gear in a relatively non-rotatable manner;
A second case engaged with the output shaft so as not to rotate relative to the output shaft;
It is arranged between the first case and the second case, and is compressed and deformed when a relative rotation occurs between the first case and the second case due to an impact during torque transmission. A buffer member,
The first case and the second case have a stopper portion that restricts the compression rate when the buffer member is compressed and deformed with relative rotation of the two cases, and the stopper portion is made of resin. In addition, the engaging part of the first case that engages with the pinion gear so as not to rotate relative to the pinion gear and the engaging part of the second case that engages with the output shaft so as not to rotate relative to each other are made of metal. Starter characterized by being. The starter according to any one of claims 1 to 3,
The shock absorbing device has at least one intermediate case between the first case and the second case, and the buffer member is disposed between each case,
The intermediate case is provided with a stopper portion that regulates the compression rate of the buffer member between the first case, the second case, or between the intermediate cases. A starter characterized by The starter according to claim 4,
A starter characterized in that a hollow portion is formed in a stopper portion provided in the intermediate case. The starter according to claim 4,
The starter characterized in that the intermediate case is made of resin. The starter according to any one of claims 1 to 6,
A torque limiter provided in a torque transmission path between the motor and the output shaft, the torque limiter having a rotating plate whose rotation is restricted by a frictional force, and an excessive torque exceeding the slipping torque of the rotating plate; When applied to the rotating plate, the rotating plate slides against the frictional force (rotates), thereby interrupting transmission of excessive torque. The starter according to any one of claims 1 to 7,
A starter used for an engine automatic stop / restart system for automatically controlling engine stop and restart.

Images