JP4179259B2 - Starter - Google Patents

Description

  The present invention relates to a decelerating starter that decelerates rotation of a motor and transmits it to an engine.

As a prior art, there is a starter disclosed in Patent Document 1.
The starter includes a first reduction gear that meshes with a pinion formed on the armature shaft of the motor, and a second reduction gear that is provided coaxially with the first reduction gear and rotates integrally with the first reduction gear. The second reduction gear is meshed with the starter drive gear. The starter driving gear is connected to a boss portion fixed to the crankshaft of the engine via a one-way clutch. Thereby, the rotation of the motor is transmitted from the pinion to the first reduction gear and decelerated, and further decelerated by the second reduction gear and transmitted to the starter drive gear. The rotation of the starter drive gear is transmitted to the crankshaft via the one-way clutch, so that the engine is started.
JP-A-10-122107

However, in the starter described in the above-mentioned Patent Document 1, the rotation of the motor is reduced in two stages using the first reduction gear and the second reduction gear. When the required torque of the engine increases, it is conceivable that the input from the starter side is insufficient. It is also possible to increase the reduction ratio by changing the reduction gear module. However, this increases the size of the starter (especially the size in the radial direction), which deteriorates the ease of mounting on the engine. Occurs.
The present invention has been made based on the above circumstances, and an object thereof is to provide a starter capable of setting a high reduction gear ratio without causing an increase in size.

(Invention of Claim 1 )
The present invention is provided between a motor that generates rotational force, a drive shaft disposed on the same axis as the armature shaft of the motor, and between the armature shaft and the drive shaft of the motor, and reduces the rotation of the motor. A planetary gear reduction device that transmits to the drive shaft, a starter gear that is provided in a cylindrical shape that fits to the outer periphery of the drive shaft, and that has an external gear formed in a part of the axial direction and rotates integrally with the drive shaft, A first reduction gear that meshes with the external gear to reduce the rotation of the starter gear, and is arranged coaxially with the first reduction gear, meshes with the engine gear, transmits torque from the first reduction gear, and rotates. A second reduction gear that decelerates the rotation of the first reduction gear and transmits it to the engine gear; and an inner peripheral side of the second reduction gear, and the second reduction gear rotates the rotation of the first reduction gear. And the second reduction gear And a one-way clutch for preventing the first reduction gear from being rotated, the second reduction gear is disposed closer to the motor side in the axial direction than the first reduction gear, and is disposed outside the first reduction gear. The first reduction gear, the second reduction gear, and the one-way clutch are disposed within a range of an axial length of the starter gear .

According to the above configuration, the reduction ratio can be set high by reducing the rotation of the motor in three stages by the planetary gear reduction device, the first reduction gear, and the second reduction gear. Thereby, even when the required torque of the engine increases, the starter starting torque can be sufficiently ensured, so that the engine startability is improved. In addition, since the speed is reduced in three stages in order to increase the reduction ratio, the size of the starter is not increased and the mountability to the engine is excellent as compared with the starter described in Patent Document 1.
In addition, since the torque transmission from the engine side to the starter side can be interrupted by the one-way clutch, an overrun after the engine is started can be prevented.
Furthermore, since the first reduction gear and the second reduction gear are arranged coaxially, a one-way clutch can be suitably arranged between the two gears. That is, since a space in which the one-way clutch can be arranged between both gears can be easily secured, the degree of freedom of arrangement of the one-way clutch is improved, and an increase in the size of the starter by providing the one-way clutch can be suppressed.
Since the second reduction gear is disposed on the motor side in the axial direction from the first reduction gear and has an outer diameter smaller than that of the first reduction gear, by using the second reduction gear, The physique in the radial direction does not increase, and the physique increase in the axial direction can also be suppressed.
Further, since the first reduction gear, the second reduction gear, and the one-way clutch are not disposed beyond the range of the axial length of the starter gear, the first reduction gear, the second reduction gear, and By providing the one-way clutch, the size does not increase in the axial direction, and a compact starter can be realized in the axial direction.

(Invention of Claim 2 )
The starter gear according to claim 1 , wherein the starter gear is splined to the outer periphery of the drive shaft, and at least a part of the meshing portion between the external gear and the first reduction gear is within an axial range of the spline coupling portion. It is arranged.
If the spline coupling portion and the meshing portion are separated from each other in the axial direction, a torsional torque is applied to the starter gear during torque transmission, so that torque transmission efficiency is reduced and torque cross is generated. On the other hand, if at least a part of the meshing portion of the external gear and the first reduction gear is disposed within the axial range of the spline coupling portion, the torque cross due to the twist of the starter gear is reduced, so that the engine is started. Improves. Desirably, the engagement portion is disposed within the axial range of the spline coupling portion.

  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, and FIG. 2 is a front view of the starter 1 viewed from the front side. As shown in FIG. 1, the starter 1 shown in the first embodiment includes a motor 3 that generates a rotational force in the armature 2 and an electromagnetic switch that opens and closes a motor contact (not shown) provided in an energization circuit of the motor 3. 4, a drive shaft 5 disposed on the same axis as the rotation shaft of the armature 2 (referred to as the armature shaft 2 a), and a planetary gear reduction device 6 that decelerates the rotation of the motor 3 and transmits it to the drive shaft 5. The starter gear 7 that engages with the outer periphery of the drive shaft 5 and rotates integrally with the drive shaft 5, the first reduction gear 8 that decelerates the rotation of the starter gear 7, and the rotation of the first reduction gear 8 is reduced. The second reduction gear 10 is transmitted to the ring gear 9 of the engine.

The motor 3 is a well-known DC motor including a field that generates magnetic flux, the armature 2 having the commutator 11, a brush 12 disposed on the commutator 11, and the motor contact is provided by the electromagnetic switch 4. When closed, power is supplied from a battery (not shown) to cause the armature 2 to generate a rotational force.
The field magnet is configured by arranging a plurality of permanent magnets 14 on the inner periphery of a yoke 13 forming a magnetic circuit. A field winding can be used instead of the permanent magnet 14. The yoke 13 is disposed between a front housing 15 that covers the front side of the starter 1 (left side in FIG. 1) and an end frame 16 that covers the rear part of the motor 3, and also serves as a machine frame of the motor 3.

  The electromagnetic switch 4 includes, for example, an excitation coil that is energized from a battery by closing a start switch (not shown) that is manually operated by the driver, a plunger that operates by receiving the magnetic force generated by the excitation coil, and the plunger And a set of fixed contacts connected to the energizing circuit of the motor 3 via two external terminals 17 and 18 (see FIG. 1). Built-in, the movable contact comes into contact with a set of fixed contacts and conducts between the two fixed contacts, the motor contact is closed, the movable contact is separated from the set of fixed contacts, and the two fixed contacts are connected. Is interrupted, the motor contact is opened.

  The planetary gear speed reduction device 6 includes a sun gear 19 formed on the armature shaft 2a, an internal gear 21 that is restricted in rotation via an impact absorbing device 20, and a plurality of planetary gears 22 that mesh with both gears 19 and 21. The planetary gear 22 is rotatably supported by a support pin 23 via a bearing, and the support pin 23 is fixed to a carrier 24 provided integrally with the drive shaft 5. In this planetary gear reduction device 6, when the rotation of the armature 2 is transmitted to the planetary gear 22 via the sun gear 19, the planetary gear 22 rotates (rotates) and revolves around the sun gear 19. The rotation of the armature 2 is decelerated to the revolution speed of the sun gear 19 and transmitted to the drive shaft 5.

The shock absorbing device 20 has a rotating disk 25 that engages with the internal gear 21, and this rotating disk 25 is urged toward the center plate 26 side (left side in FIG. 1) by a disc spring via a fixed disk. The rotation is restricted by frictional engagement between the plate 26 and the fixed disk. The rotation of the fixed disk is restricted by the center plate 26, and the center plate 26 is engaged with the inner periphery of the front housing 15 and the rotation is restricted. In this shock absorbing device 20, when an excessive torque exceeding the stationary torque of the rotating disk 25 is applied to the internal gear 21, the rotating disk 25 is allowed to slide (rotate) so that the internal gear 21 is allowed to rotate, and the excessive torque is exceeded. Can be absorbed.

  The starter gear 7 has a cylindrical shape, and a straight spline 7 a is formed on the inner peripheral surface of the tip. The straight spline 7 a meshes with the straight spline 5 a formed on the outer peripheral surface of the drive shaft 5. The outer periphery of the starter gear 7 is rotatably supported by the front housing 15 via a pair of bearings 27 while being fitted to the outer periphery. An external gear 28 is formed in a part of the starter gear 7 in the axial direction, and the first reduction gear 8 is meshed with the external gear 28. The external gear 28 is provided in the axial direction front end side of the starter gear 7, specifically, in the axial range where the straight spline 7 a is formed.

The first reduction gear 8 is rotatably supported by an intermediate shaft 29 arranged in parallel with the drive shaft 5 via a bearing 30. The first reduction gear 8 has a diameter larger than that of the external gear 28 of the starter gear 7, and meshes with the external gear 28 and rotates to reduce the rotation of the starter gear 7.
Both ends of the intermediate shaft 29 are fixed to the front housing 15 by press fitting or the like.
The second reduction gear 10 is disposed coaxially with the first reduction gear 8 via the clutch 31 and close to the axial motor side (right side in FIG. 1) of the first reduction gear 8. Arranged and meshed with the ring gear 9 of the engine. The second reduction gear 10 is rotated integrally with the first reduction gear 8 via the clutch 31 to transmit the rotation to the ring gear 9. However, the second reduction gear 10 rotates at the same rotational speed as the first reduction gear 8, but is provided with a smaller outer diameter than the first reduction gear 8, thereby rotating the first reduction gear 8. Decelerate and transmit to ring gear 9.

The clutch 31 includes an inner portion 31a provided integrally with the boss portion 8a of the first reduction gear 8, an outer portion 31b that engages with the inner peripheral side of the second reduction gear 10, an inner portion 31a, and an outer portion. The inner part 31a and the outer part 31b are provided via a pair of ball bearings 32 so as to be relatively rotatable. The clutch 31 is configured as a one-way clutch 31 that transmits torque from the inner portion 31a to the outer portion 31b via the sprag 31c and blocks torque transmission from the outer portion 31b to the inner portion 31a. Accordingly, when the rotation speed of the second reduction gear 10 exceeds the rotation speed of the first reduction gear 8 by starting the engine, the sprag 31c idles and the torque transmission from the outer portion 31b to the inner portion 31a is interrupted. Thus, the first reduction gear 8 can be prevented from being turned by the second reduction gear 10.
The first reduction gear 8, the second reduction gear 10, and the clutch 31 are disposed within the range of the axial length of the starter gear 7 as shown in FIG. 1.

Next, the operation of the starter 1 will be described.
When the motor contact is closed by the electromagnetic switch 4 and power is supplied to the armature 2, a rotational force is generated in the armature 2, and the rotation of the armature 2 is decelerated by the planetary gear reduction device 6 and transmitted to the drive shaft 5. The The rotation of the drive shaft 5 is decelerated by the first reduction gear 8 that meshes with the external gear 28 of the starter gear 7, further reduced by the second reduction gear 10, and transmitted to the ring gear 9.
When the rotation speed of the second reduction gear 10 meshed with the ring gear 9 exceeds the rotation speed of the first reduction gear 8 by starting the engine, the first reduction gear 8 and the second reduction gear 10 are Therefore, the rotation of the second reduction gear 10 is not transmitted to the first reduction gear 8, and the engine drive torque can be prevented from being transmitted to the motor 3 side.

(Effect of Example 1)
In the starter 1 described in the first embodiment, since the rotation of the motor 3 is reduced in three stages by the planetary gear reduction device 6, the first reduction gear 8, and the second reduction gear 10, the reduction ratio can be set high. . As a result, even when the required torque of the engine becomes large, the starter torque of the starter 1 can be sufficiently secured, and the engine startability is improved. Further, since the rotation reduced by the planetary gear reduction device 6 is further reduced by the first reduction gear 8 and the second reduction gear 10, the first reduction gear 8 and the second reduction gear 10 are compared. Compared with the starter described in Patent Document 1, the physique of the starter 1 does not increase in size and is excellent in mountability to the engine.

Further, since the second reduction gear 10 is disposed coaxially with the first reduction gear 8, the use of the second reduction gear 10 does not increase the physique in the radial direction, and Since the second reduction gear 10 is disposed on the axial motor 3 side (the right side in FIG. 1) of the first reduction gear 8, an increase in the size in the axial direction can also be suppressed.
Furthermore, since the first reduction gear 8 and the second reduction gear 10 are arranged coaxially, the clutch 31 can be suitably arranged between the two gears 8 and 10. That is, a space in which the clutch 31 can be disposed between the gears 8 and 10 can be easily secured. Therefore, the degree of freedom of arrangement of the clutch 31 is improved, and an increase in the size of the starter 1 due to the provision of the clutch 31 can be suppressed.

  In the starter 1 described in the first embodiment, the first reduction gear 8, the second reduction gear 10, and the clutch 31 are arranged within the range of the axial length of the starter gear 7. In other words, the first reduction gear 8, the second reduction gear 10, and the clutch 31 are not arranged beyond the range of the axial length of the starter gear 7. By providing the reduction gear 10 and the clutch 31, the physique does not increase in the axial direction, and the compact starter 1 can be realized in the axial direction.

  The external gear 28 provided in the starter gear 7 is provided in the axial range where the straight spline 7a of the starter gear 7 is formed. In this case, the meshing portion of the external gear 28 and the first reduction gear 8 is disposed within the axial range of the spline coupling portion where the straight spline 5a of the drive shaft 5 and the straight spline 7a of the starter gear 7 mesh. The torque cross during torque transmission can be reduced. That is, if the spline coupling portion and the meshing portion are separated from each other in the axial direction, a torsional torque is applied to the starter gear 7 at the time of torque transmission, so that torque transmission efficiency is reduced and torque cross is generated. On the other hand, when the meshing portion is disposed within the axial range of the spline coupling portion, the torcross due to torsion of the starter gear 7 hardly occurs, so that the engine startability is improved.

FIG. 3 is a partial cross-sectional view of the starter 1.
In the first embodiment, the meshing portion of the external gear 28 and the first reduction gear 8 is disposed within the axial range of the spline coupling portion where the straight spline 5a of the drive shaft 5 and the straight spline 7a of the starter gear 7 mesh. However, as shown in FIG. 3, at least a part of the meshing portion may be arranged within the range in the axial direction of the spline coupling portion.
Even in the configuration of the second embodiment, twisting of the starter gear 7 that occurs during torque transmission can be suppressed and the torque cross can be reduced, so that good engine startability can be ensured.

(Modification)
In the first embodiment, the sprag type one-way clutch 31 is shown. However, a wedge-shaped cam chamber is formed on the inner periphery of the outer portion 31b or the outer periphery of the inner portion 31a, and a roller is disposed in the cam chamber. A roller-type one-way clutch that transmits torque from the inner portion 31a to the outer portion 31b via this roller can also be employed.

(Example 1) which is a half sectional view of a starter. (Example 1) which is the front view of the starter seen from the front side. (Example 2) which is a partial sectional view of a starter.

Explanation of symbols

1 starter 2a armature shaft 3 motor 5 drive shaft 6 the planetary gear reduction device 7 starter gear 8 first deceleration tooth wheel 9 ring gear (engine gear)
10 second reduction gears on 28 external gear 31 one-way clutch

Claims (2)

A motor that generates rotational force;
A drive shaft disposed on the same axis as the armature shaft of the motor;
A planetary gear reduction device that is provided between the armature shaft of the motor and the drive shaft, and that decelerates the rotation of the motor and transmits it to the drive shaft;
A starter gear that is provided in a cylindrical shape that fits on the outer periphery of the drive shaft, has an external gear formed in a part in the axial direction, and rotates integrally with the drive shaft;
A first reduction gear meshing with the external gear to reduce the rotation of the starter gear;
The first reduction gear is arranged coaxially and meshed with the engine gear, and is rotated by torque transmitted from the first reduction gear, thereby reducing the rotation of the first reduction gear to the engine gear. A second reduction gear to transmit ;
Arranged on the inner peripheral side of the second reduction gear, the rotation of the first reduction gear is transmitted to the second reduction gear, and the first reduction gear is rotated by the second reduction gear. With a one-way clutch to prevent
The second reduction gear is disposed closer to the motor side in the axial direction than the first reduction gear, and has an outer diameter smaller than that of the first reduction gear.
The starter, wherein the first reduction gear, the second reduction gear, and the one-way clutch are arranged within a range of an axial length of the starter gear . The starter according to claim 1 ,
The starter gear is splined to the outer periphery of the drive shaft, and at least a part of the meshing portion of the external gear and the first reduction gear is disposed within the axial range of the spline coupling portion. Starter characterized by.

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