JP6148443B2 - Reduction mechanism and motor with reduction gear - Google Patents

Description

  The present invention relates to a speed reduction mechanism and a motor with a speed reducer.

For example, a wiper device for wiping the front glass of an automobile is equipped with a reduction gear equipped with a reduction mechanism that increases the rotational force of the rotating shaft of the electric motor in order to swing the wiper blade with a small electric motor. A motor (wiper motor) is used.
As a reduction mechanism, there is a mechanism having a worm shaft integrally provided on a rotating shaft of an electric motor and a worm wheel meshing with the worm shaft. Thus, a large reduction ratio can be obtained by employing a worm shaft and a worm wheel as a speed reduction mechanism (see, for example, Patent Document 1).

JP 2008-199775 A

  By the way, further reduction in size and weight is desired for a motor with a reduction gear mounted in an automobile or the like. Here, in order to reduce the size of the electric motor constituting the motor with a speed reducer, it is conceivable to increase the speed reduction ratio of the speed reduction mechanism. This is because a large output can be obtained with a small driving force by increasing the reduction ratio. As a method of increasing the reduction ratio, for example, a method of decreasing the number of worm shafts (number of teeth) from 2 to 1 or a method of increasing the number of worm wheel teeth is used. Conceivable.

  However, when the number of worm shafts is reduced, there is a problem in that it is difficult to effectively reduce the size of the electric motor due to a reduction in deceleration efficiency. Further, when increasing the number of teeth of the worm wheel, it is necessary to make the module the same as before the increase in the number of teeth from the viewpoint of maintaining the strength of the worm wheel, and there is a problem that the worm wheel becomes large.

  Accordingly, the present invention has been made in view of the above-described circumstances, and provides a speed reduction mechanism and a motor with a speed reducer that can be effectively reduced in size.

In order to solve the above-described problems, a speed reduction mechanism according to the present invention is housed in a worm shaft that rotates by receiving external rotational force , and a box-shaped gear housing that meshes with the worm shaft and has an opening. The worm shaft has a shaft main body and a shaft tooth portion formed on the outer peripheral surface of the shaft main body, and the worm wheel includes the wheel main body and the outer peripheral surface of the wheel main body. A small tooth portion that engages with the wheel tooth portion together with the wheel tooth portion on the outer peripheral surface of the wheel body, and the small tooth portion is located on the worm shaft side. An elastic member provided with an urging mechanism for applying an urging force to the worm wheel so as to be pressed, the urging mechanism being provided so as to be able to protrude and retract with respect to a bottom plate that closes the opening of the gear housing. When Wherein provided on the center axis of the worm wheel, and a pressing plate which is urged to the worm wheel side by the elastic member, each of said bottom plate and said pressing plate, retaining portion to each other is engaged The end portion of the worm wheel that faces the pressing plate in the axial direction is provided with a substantially annular small ring portion that protrudes toward the pressing plate .

With this configuration, the meshing area of the worm wheel with the worm shaft can be increased. For this reason, the strength of the worm wheel can be maintained even if the module is set to be small while increasing the number of teeth of the worm wheel. For this reason, the enlargement of the worm wheel can be prevented while increasing the reduction ratio, and the reduction mechanism can be effectively downsized.
Further, the small tooth portion of the worm wheel can always be meshed with the shaft tooth portion of the worm shaft. For this reason, the meshing area of the worm wheel with respect to the worm shaft can always be kept constant, and the speed reduction mechanism can be downsized reliably and effectively.
Furthermore, the small tooth portion of the worm wheel can be pressed toward the worm shaft side with a simple structure. For this reason, it is possible to reduce the size of the speed reduction mechanism at low cost.

  The speed reduction mechanism according to the present invention is characterized in that a side portion of the small tooth portion on the shaft main body side is curved.

  By comprising in this way, the meshing area of the worm wheel with respect to the worm shaft can be further increased as compared with the case where the side portion of the small tooth portion on the shaft body side is not curved. For this reason, it becomes possible to miniaturize the speed reduction mechanism more effectively.

  A motor with a speed reducer according to the present invention includes a speed reduction mechanism and an electric motor attached to the speed reduction mechanism, and is characterized in that a rotating shaft of the electric motor and the worm shaft are connected.

  By comprising in this way, the motor with a reduction gear which can be reduced in size effectively can be provided.

According to the present invention, the meshing area of the worm wheel with the worm shaft can be increased. For this reason, the strength of the worm wheel can be maintained even if the module is set to be small while increasing the number of teeth of the worm wheel. For this reason, the enlargement of the worm wheel can be prevented while increasing the reduction ratio, and the reduction mechanism can be effectively downsized.
Further, the small tooth portion of the worm wheel can always be meshed with the shaft tooth portion of the worm shaft. For this reason, the meshing area of the worm wheel with respect to the worm shaft can always be kept constant, and the speed reduction mechanism can be downsized reliably and effectively.
Furthermore, the small tooth portion of the worm wheel can be pressed toward the worm shaft side with a simple structure. For this reason, it is possible to reduce the size of the speed reduction mechanism at low cost.

It is a perspective view of the motor with a reduction gear in the embodiment of the present invention. It is a schematic block diagram of the deceleration mechanism in embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is the B section enlarged view of FIG. It is a longitudinal cross-sectional view of the worm wheel in the 1st modification of 1st Embodiment of this invention. It is a longitudinal cross-sectional view of the worm wheel in the 2nd modification of 1st Embodiment of this invention. It is a principal part longitudinal cross-sectional view of the deceleration mechanism in 2nd Embodiment of this invention.

(First embodiment)
(Motor with reduction gear)
Next, a first embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a perspective view of a motor with a reduction gear.
As shown in the figure, the motor 1 with a speed reducer includes an electric motor 2 and a speed reduction mechanism 4 to which a motor casing 3 of the electric motor 2 is attached.
The motor casing 3 is formed in a bottomed cylindrical shape, and is arranged in a state where an opening (not shown) is directed to the speed reduction mechanism 4 side. A rotation shaft 8 (see FIG. 2) is rotatably provided in the motor casing 3. The speed reduction mechanism 4 is connected to the rotating shaft 8.

(Deceleration mechanism)
2 is a schematic configuration diagram of the speed reduction mechanism, and FIG. 3 is a cross-sectional view taken along the line AA of FIG.
As shown in FIGS. 1 to 3, the speed reduction mechanism 4 has a box-shaped gear housing 5 having an opening 5 a on one surface. A motor mounting portion 6 to which the electric motor 2 is mounted is formed on the side surface of the gear housing 5. The motor mounting portion 6 is formed in a cylindrical shape so that the electric motor 2 can be received. An outer flange portion 7 is formed on the outer opening edge of the motor mounting portion 6. It arrange | positions so that the opening end of the motor casing 3 may overlap with this outer flange part 7, and the gear housing 5 and the motor casing 3 are fastened and fixed with the volt | bolt 9. FIG.

  A bottom plate 15 is provided in the opening 5a of the gear housing 5 so as to close the opening 5a. A gear group 10 is housed in a space closed by the gear housing 5 and the bottom plate 15. The gear group 10 includes a worm shaft 11 connected to the rotary shaft 8 of the electric motor 2, a pair of stepped gears 12 and 13 that mesh with the worm shaft 11, and a spur gear that meshes with the pair of stepped gears 12 and 13. 14.

  The worm shaft 11 has a shaft body 16. One end of the shaft body 16 is connected to the rotating shaft 8, and the other end is rotatably supported by the gear housing 5. The shaft body 16 is provided with a first tooth portion 16a and a second tooth portion 16b so as to be reverse screws. The first tooth portion 16a and the second tooth portion 16b are formed in one or two strips. However, the first tooth portion 16a and the second tooth portion 16b may be formed in three or more strips.

  A pair of stepped gears 12 and 13 are arranged on both sides of the worm shaft 11, the stepped gear 12 is meshed with the first tooth portion 16a, and the stepped gear 13 is meshed with the second tooth portion 16b. Yes. Since the 1st tooth part 16a and the 2nd tooth part 16b are mutually reverse screws, a pair of stepped gears 12 and 13 rotate in the same direction, respectively. That is, the worm shaft 11 and the pair of stepped gears 12 and 13 constitute a so-called Marshall mechanism, and the thrust force applied to the worm shaft 11 is offset by the pair of stepped gears 12 and 13. .

  Hereinafter, the pair of stepped gears 12 and 13 will be described in detail. In addition, since a pair of stepped gears 12 and 13 are comprised similarly, in the following description, only one stepped gear 12 of a pair of stepped gears 12 and 13 is demonstrated, About the other stepped gear 13, the code | symbol similar to one stepped gear 12 is attached | subjected, and description is abbreviate | omitted.

(Stepped gear)
FIG. 4 is an enlarged view of a portion B in FIG.
As shown in FIGS. 2 to 4, the stepped gear 12 is formed by integrally molding a worm wheel 17 that meshes with the worm shaft 11 and a pinion gear 18 that has a smaller diameter than the worm wheel 17.
The worm wheel 17 has a wheel main body 19 formed in a substantially disc shape. Concave portions 20 are formed on both surfaces of the wheel main body 19 in most of the center in the radial direction. A wheel tooth portion 19 a that meshes with the first tooth portion 16 a of the worm shaft 11 is formed on the outer peripheral surface of the wheel body 19.

  Further, a small tooth portion 21 protrudes over the entire circumference of the outer peripheral surface of the wheel body 19 at the end in the axial direction bottom plate 15 (upper end in FIG. 3). The small teeth 21 are set to the same number as the number of teeth of the wheel teeth 19a. The small tooth portion 21 is meshed with the region Ar <b> 1 on the bottom plate 15 side and the worm wheel 17 side of the first tooth portion 16 a of the worm shaft 11 with respect to the shaft center of the worm shaft 11. It has become.

  Further, in the small tooth portion 21, the side portion 21a on the shaft main body 16 side of the worm shaft 11 is curved, and the side portion 21a and the wheel tooth portion 19a of the wheel main body 19 are smoothly connected. ing. Here, the curvature radius R1 of the side portion 21a of the small tooth portion 21 is set to be approximately equal to the shaft diameter E1 of the shaft body 16 of the worm shaft 11 or slightly larger than the shaft diameter E1.

  A pinion gear 18 projects from the recess 20 on the bottom plate 15 side of the wheel body 19 at the center in the radial direction. A shaft insertion recess 22 having an opening 22 a on the opposite side of the bottom plate 15 is formed in the shaft center of the pinion gear 18. The idler shaft 23 is inserted into the shaft insertion recess 22, and the stepped gear 12 is rotatably supported on the idler shaft 23. The idler shaft 23 is fixed to the bearing portion 24 formed on the bottom portion 5b of the gear housing 5 by press fitting or the like.

Further, in the shaft insertion recess 22 of the pinion gear 18, a ring portion 25 projects from a bottom surface 22 b on the bottom plate 15 side. The ring portion 25 is for reducing the contact area between the end of the idler shaft 23 and the shaft insertion recess 22 of the pinion gear 18 and reducing the sliding resistance of the pinion gear 18 with respect to the idler shaft 23.
On the other hand, a small ring portion 26 is formed at the tip of the pinion gear 18 on the bottom plate 15 side. The protruding height of the small ring portion 26 is set lower than the ring portion 25 formed in the shaft insertion recess 22. The small ring portion 26 is for reducing the contact area between an urging mechanism 34 described later and the tip of the pinion gear 18, and reducing the sliding resistance of the pinion gear 18 with respect to the urging mechanism 34.

(Biasing mechanism)
In the bottom plate 15, through holes 15 a are formed at locations corresponding to the pinion gears 18, and a bottom cover 27 that covers these through holes 15 a from the outside on the opposite side of the gear housing 5 is provided. An urging mechanism 34 is provided in the through hole 15a. The urging mechanism 34 includes a pressing member 32 and a coil spring 29 that urges the pressing plate 28 toward the pinion gear 18 side.

The pressing member 32 has a substantially disc-shaped pressing plate 28. A tongue piece 30 that extends toward the bottom plate 15 and can be inserted into the through hole 15a of the bottom plate 15 is integrally formed in the pressing plate 28 along the circumferential direction. As a result, the pressing plate 28 is provided so as to be able to appear and retract with respect to the through hole 15a.
Moreover, the tongue piece part 30 is formed so that elastic deformation is possible along a radial direction. Further, a retaining claw 30a is formed at the tip of the tongue piece 30 toward the radially outer side, while a retaining claw 31 is formed at the opening edge of the through hole 15a formed in the bottom plate 15. Has been. As a result, the pressing member 32 can be easily assembled in the through hole 15a, and the removal of the once assembled pressing member 32 from the through hole 15a can be restricted.

  A ring-shaped spring position restricting portion 33 is erected on the through hole 15 a side of the pressing plate 28. The coil spring 29 is stored in a compressed state in the through hole 15a so as to be fitted on the spring position restricting portion 33. As a result, the pressing member 32 is biased toward the pinion gear 18 side. Then, the pressing plate 28 of the pressing member 32 comes into contact with the small ring portion 26 of the pinion gear 18 and presses the pinion gear 18 toward the bottom portion 5b of the gear housing 5 in this state.

  Here, when the pinion gear 18 is pressed, the worm wheel 17 is also pressed toward the bottom 5 b side of the gear housing 5. As a result, the small tooth portion 21 formed on the outer peripheral surface of the worm wheel 17 abuts on the worm shaft 11, and the worm wheel 17 and the pinion gear 18 are positioned in the axial direction.

At this time, a gap S <b> 1 is set between the worm wheel 17 and the bottom portion 5 b of the gear housing 5. Further, a gap S1 ′ is also set between the ring portion 25 formed in the shaft insertion recess 22 of the pinion gear 18 and the idler shaft 23.
That is, the worm wheel 17 abuts against the bottom 5b of the gear housing 5 or the ring portion 25 of the pinion gear 18 with insufficient engagement between the small tooth portion 21 of the worm wheel 17 and the first tooth portion 16a of the worm shaft 11. And the idler shaft 23 can be prevented from coming into contact with each other.

  The spur gear 14 is meshed with the pinion gears 18 and 18 of the pair of stepped gears 12 and 13 thus configured. The spur gear 14 is rotatably supported by the bottom portion 5 b of the gear housing 5 and the bottom plate 15. An output shaft 62 is press-fitted into the radial center of the spur gear 14. One end of the output shaft 62 protrudes from the bottom 5b of the gear housing 5, and is connected to an external mechanism for driving a wiper or the like, for example.

  Under such a configuration, when the rotating shaft 8 rotates by driving the electric motor 2, the worm shaft 11 connected to the rotating shaft 8 rotates. Then, the worm wheel 17 of the pair of stepped gears 12, 13 meshed with the first tooth portion 16 a and the second tooth portion 16 b of the worm shaft 11 rotates, and the pinion gear integrated with the worm wheel 17. 18 rotates. Then, the spur gear 14 meshed with the pinion gear 18 rotates, and the driving force of the motor 1 with speed reducer is transmitted to the external mechanism via the output shaft 62.

  Here, since the worm wheel 17 of the pair of stepped gears 12 and 13 has the small tooth portion 21 formed on the outer peripheral surface, the meshing area between the worm wheel 17 and the worm shaft 11 increases accordingly.

This will be described in more detail with reference to FIG.
As shown in the figure, when the small tooth portion 21 is not formed on the outer peripheral surface of the worm wheel 17 (see the two-dot chain line in FIG. 4), the wheel tooth portion 19 a of the worm wheel 17 and the first tooth of the worm shaft 11. The contact area with the portion 16a (second tooth portion 16b) is the area of the hatched portion M1 in FIG.
On the other hand, when the small tooth portion 21 is formed on the outer peripheral surface of the worm wheel 17, the contact area portion between the small tooth portion 21 and the first tooth portion 16a (second tooth portion 16b) of the worm shaft 11 (FIG. 4). The area of meshing between the worm wheel 17 and the worm shaft 11 is increased by the area of the hatch portion M2 in FIG.

(effect)
Therefore, according to the first embodiment described above, the strength of the worm wheel 17 can be maintained even when the module is set small while increasing the number of teeth of the wheel tooth portion 19a of the worm wheel 17. For this reason, the enlargement of the worm wheel 17 can be prevented while increasing the speed reduction ratio of the speed reduction mechanism 4, and the speed reduction mechanism 4 can be effectively downsized.

  Further, in the small tooth portion 21, the side portion 21a on the shaft main body 16 side of the worm shaft 11 is curved, and the side portion 21a and the wheel tooth portion 19a of the wheel main body 19 are smoothly connected. ing. For this reason, compared with the case where the side part 21a of the small tooth part 21 is not curvedly formed, the meshing area of the worm wheel 17 with respect to the worm shaft 11 can be further increased. Therefore, the speed reduction mechanism 4 can be more effectively downsized.

  Further, an urging mechanism 34 is provided at a position corresponding to the pair of stepped gears 12 and 13 of the bottom plate 15, and the pair of stepped gears 12 and 13 are pressed toward the bottom 5 b side of the gear housing 5. Yes. For this reason, the small tooth portion 21 formed on the worm wheel 17 of the pair of stepped gears 12 and 13 can always mesh with the first tooth portion 16a and the second tooth portion 16b of the worm shaft 11, respectively. . For this reason, the meshing area of the worm wheel 17 with respect to the worm shaft 11 can always be kept constant, and the speed reduction mechanism 4 can be downsized reliably and effectively.

  Since the urging mechanism 34 includes the pressing member 32 and the coil spring 29 that urges the pressing plate 28 toward the pinion gear 18, the structure of the urging mechanism 34 can be simplified. it can. For this reason, it is possible to provide a small speed reduction mechanism 4 at low cost.

  In the first embodiment described above, the wheel main body 19 of the worm wheel 17 has a small tooth portion 21 projecting over the entire circumference at the axial bottom plate 15 side end (upper end in FIG. 3) of the outer peripheral surface. The case where it is provided has been described. In the small tooth portion 21, the side portion 21a of the worm shaft 11 on the shaft main body 16 side is curved, and the side portion 21a and the wheel tooth portion 19a of the wheel main body 19 are smoothly connected. Explained the case. However, the shape is not limited to this, and any shape that increases the meshing area of the worm wheel 17 with the worm shaft 11 may be used. This will be specifically described below.

(First modification of the first embodiment)
FIG. 5 is a longitudinal sectional view of a worm wheel in a first modification of the first embodiment.
That is, as shown in the figure, the side portion 21a of the small tooth portion 21 formed on the worm wheel 17 may not be curved. Even when the small tooth portion 21 is formed in this way, the meshing area of the worm wheel 17 with the worm shaft 11 can be increased as compared with the case where the small tooth portion 21 is not formed.

(Second modification of the first embodiment)
FIG. 6 is a longitudinal sectional view of a worm wheel in a second modification of the first embodiment.
As shown in the figure, not only the axial bottom plate 15 side end (upper end in FIG. 6) of the outer peripheral surface of the wheel main body 19 of the worm wheel 17 but also the bottom 5b side end of the gear housing 5 in the axial direction ( Small teeth 21 may also be formed on the lower end in FIG. At this time, the radius of curvature R2 of the arc formed by the side portions 21a and 21a of the pair of small tooth portions 21 and 21 is substantially equal to the shaft diameter E1 of the shaft body 16 of the worm shaft 11 or larger than the shaft diameter E1. What is necessary is just to set it to a somewhat large extent.

  Therefore, according to the second modification of the first embodiment, the meshing area of the worm wheel 17 with respect to the worm shaft 11 can be further increased as compared with the first embodiment. For this reason, in addition to the effect similar to the first embodiment described above, the speed reduction mechanism 4 can be more effectively downsized.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIG. In addition, the same code | symbol is attached | subjected and demonstrated to the same aspect as 1st Embodiment.
FIG. 7 is a longitudinal sectional view of an essential part of the speed reduction mechanism in the second embodiment, and corresponds to FIG.
In the second embodiment, the motor 1 with a speed reducer includes an electric motor 2 and a speed reduction mechanism 104 to which a motor casing 3 of the electric motor 2 is attached. The speed reduction mechanism 104 is open on one side. A box-shaped gear housing 105, a bottom plate 115 for closing the opening of the gear housing 105, a gear group 110 provided in a space closed by the gear housing 105 and the bottom plate 115, and a gear group The gear group 110 includes a worm shaft 11 connected to the rotating shaft 8 of the electric motor 2 and a pair of stepped gears 112 that mesh with the worm shaft 11. 13 and the spur gear 14 that meshes with the pair of stepped gears 112 and 13 are the same as in the first embodiment. A.

  Here, as shown in FIG. 7, the difference between the second embodiment and the first embodiment is that the stepped gear 112 constituting the gear group 110 of the second embodiment and the urging mechanism 134 corresponding thereto. However, it is different from the stepped gear 12 constituting the gear group 10 of the first embodiment and the urging mechanism 34 corresponding thereto.

(Stepped gear)
More specifically, a small tooth portion 121 is provided on the wheel main body 119 of the worm wheel 117 in the stepped gear 112 at the bottom 105b side end of the gear housing 105 in the axial direction on the outer peripheral surface. ing. The small tooth portion 121 is meshed with the region Ar <b> 2 on the worm wheel 117 side of the first tooth portion 16 a of the worm shaft 11 on the bottom portion 105 b side of the gear housing 105 with respect to the shaft center of the worm shaft 11. It is like that.

  Further, in the small tooth portion 121, the side portion 121a on the shaft main body 16 side of the worm shaft 11 is curved, and the side portion 121a and the wheel tooth portion 119a of the wheel main body 119 are smoothly connected. ing. The curvature radius R3 of the side portion 121a of the small tooth portion 121 is set to be approximately equal to the shaft diameter E1 (see FIG. 4) of the shaft body 16 of the worm shaft 11 or slightly larger than the shaft diameter E1. .

  Further, the pinion gear 118 of the stepped gear 112 is formed with a boss portion 41 at a tip portion on the bottom plate 115 side. A small ring portion 126 is integrally formed at the tip of the boss portion 41. A through hole 115a is formed at a position corresponding to the pinion gear 118 of the bottom plate 115, and the boss portion 41 and the small ring portion 126 face the through hole 115a.

(Biasing mechanism)
On the other hand, on the bottom 105b side of the gear housing 105, a coil spring 129 that constitutes one of the urging mechanisms 134 is attached to an idler shaft 23 that rotatably supports the stepped gear 112. The coil spring 129 is in a compressed state in the recess 120 formed in the worm wheel 117.
A ring-shaped pressing plate 128 is provided at the end of the coil spring 129 on the worm wheel 117 side so as to be inserted through the idler shaft 23. The pressing plate 128 constitutes the other side of the urging mechanism 134.

That is, the urging mechanism 134 is configured to urge the stepped gear 112 toward the bottom plate 115 side when the coil spring 129 presses the stepped gear 112 via the pressing plate 128. .
When the stepped gear 112 is pressed toward the bottom plate 115 side, the small tooth portion 121 formed on the outer peripheral surface of the worm wheel 117 comes into contact with the worm shaft 11 and positioning in the axial direction is performed.

At this time, a clearance S2 is set between the small ring portion 126 formed at the tip of the pinion gear 118 and the bottom cover 27, and is formed in the shaft insertion recess 22 of the pinion gear 118. A gap S2 ′ is set between the ring portion 25 and the idler shaft 23.
As a result, the small ring portion 126 of the pinion gear 118 abuts on the bottom cover 27 or the ring of the pinion gear 118 is in contact with the bottom cover 27 while the engagement between the small tooth portion 121 of the worm wheel 117 and the first tooth portion 16a of the worm shaft 11 is insufficient. It can prevent that the part 25 and the idler shaft 23 contact | abut. Therefore, according to the second embodiment described above, the same effects as those of the first embodiment described above can be achieved.

The present invention is not limited to the above-described embodiment, and includes various modifications made to the above-described embodiment without departing from the spirit of the present invention.
For example, in the first embodiment described above, the case where the pair of stepped gears 12 and 13 that mesh with the worm shaft 11 is provided on both sides of the worm shaft 11 has been described. In the second embodiment described above, the case where the pair of stepped gears 112 and 13 that mesh with the worm shaft 11 is provided on both sides of the worm shaft 11 has been described.
However, the present invention is not limited to this, and the present invention can be applied to various reduction mechanisms including the worm shaft 11 and the worm wheels 17 and 117 meshing with the worm shaft 11.

Furthermore, in the above-described first embodiment, the case where the urging mechanism 34 includes the pressing member 32 and the coil spring 29 and the pressing plate 28 of the pressing member 32 is pressed by the coil spring 29 has been described. Further, in the above-described second embodiment, the case where the urging mechanism 134 includes the pressing plate 128 and the coil spring 129 and the pressing plate 128 is pressed by the coil spring 129 has been described.
However, the members that press the pressing plates 28 and 128 are not limited to the coil springs 29 and 129, and any members that can elastically press the pressing plates 28 and 128 may be used. For example, in place of the coil springs 29 and 129, a wave washer, an R washer, a rubber damper, or the like can be used.

1 Motor with reduction gear 2 Electric motor 4,104 Reduction mechanism
5,105 Gear housing
5a Opening 8 Rotating shaft 11 Worm shaft 12, 13, 112 Stepped gear
15, 115 Bottom plate 16 Shaft body 16a First tooth portion (shaft tooth portion)
16b 2nd tooth part (shaft tooth part)
17, 117 Worm wheel 19, 119 Wheel body 19a, 119a Wheel tooth part 21, 121 Small tooth part 21a, 121a Side part
26 Small ring portion 28, 128 Press plate 29, 129 Coil spring (elastic member)
30a, 31a Retaining claw (Retaining part)
32 Pressing members 34, 134 Energizing mechanism

Claims (3)

A worm shaft that rotates when external torque is input;
A worm wheel meshed with the worm shaft and housed in a box-shaped gear housing having an opening ,
The worm shaft has a shaft main body and a shaft tooth portion formed on the outer peripheral surface of the shaft main body,
The worm wheel has a wheel main body and a wheel tooth portion formed on the outer peripheral surface of the wheel main body,
On the outer peripheral surface of the wheel body, a small tooth portion that engages with the shaft tooth portion together with the wheel tooth portion is projected,
An urging mechanism for applying an urging force to the worm wheel so that the small tooth portion is pressed toward the worm shaft;
The biasing mechanism is
An elastic member provided so as to be able to protrude and retract with respect to a bottom plate that closes the opening of the gear housing ;
A pressing plate provided on a central axis of the worm wheel and biased toward the worm wheel by the elastic member ;
Each of the bottom plate and the pressing plate is provided with a retaining portion that engages with each other,
A speed reducing mechanism , wherein a substantially ring-shaped small ring portion protruding toward the pressing plate is provided at an end portion of the worm wheel facing the pressing plate in the axial direction . The speed reduction mechanism according to claim 1,
A speed reduction mechanism, wherein a side portion of the small tooth portion on the shaft main body side is curved. The speed reduction mechanism according to claim 1 or 2,
An electric motor attached to the speed reduction mechanism,
A motor with a speed reducer, wherein a rotating shaft of the electric motor and the worm shaft are connected.

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