Motor

Abstract

Motor (1), comprising: a motor body (2) with a rotating shaft (8); a speed reduction mechanism (11) comprising a worm shaft (15) and a worm wheel (18), which engages with the worm shaft (15); and a coupling section (16) which has a coupling hole (28) and couples the rotary shaft (8) and the worm shaft (15) together in such a way that the rotary shaft (8) and the worm shaft (15) can be rotated together, wherein the coupling section (16) is rotatable together with one of the rotary shaft (8) and the worm shaft (15), and one coupling projection (8a, 15a) is rotatable together with the other of the rotary shaft (8) and the worm shaft (15), wherein the coupling projection (8a, 15a) is inserted into the coupling hole (28), wherein a contact section (28b-28e) is provided on an inner surface of the coupling hole (28) and wherein the contact section (28b-28e) is configured such that that it can touch the coupling projection (8a, 15a) in a circumferential direction when the motor body (2) is driven to rotate the rotating shaft (8), wherein a circumferential clearance (C1), which is a clearance in the circumferential direction, and a radial clearance (C2), which is a clearance in a radial direction, between the inner surface of the coupling hole (28) and the coupling projection (8a, 15a) is formed, wherein a circumferential buffer section (31) is located in the circumferential free space, wherein a radial buffer section (32) is located in the radial free space, and wherein the contact section (28b-28e) of the coupling hole (28) and the coupling projection (8a, 15a) are configured such that they can directly touch each other in the circumferential direction while compressing and deforming the circumferential buffer section (31) in the circumferential direction when the motor body (2) is driven to rotate the rotating shaft (8).

Description

[0001] The present disclosure relates to a motor with a speed reduction mechanism comprising a worm shaft and a worm wheel.

[0002] Traditionally, this type of motor includes a worm shaft coaxially coupled to a rotating shaft, or drive shaft, of a motor body for rotation. For example, a motor disclosed in JP 2009-011 077 A includes a rotating shaft and a worm shaft made of metal. The worm shaft has a coupling section formed at an axial end. A coupling hole is formed in the coupling section. A coupling projection at a distal end of the rotating shaft is inserted into the coupling hole such that the rotating shaft and the worm shaft are directly coupled to one another.

[0003] In the motor described above, for example, if the drive shaft and the speed reduction mechanism are driven to rotate in the forward direction, the load from the output section can stop or lock the rotation. In this case, the teeth of the worm shaft, or the worm section itself, can engage with the teeth of the worm wheel. When the drive shaft and the speed reduction mechanism begin to rotate in the reverse direction from this state, torque is required not only to rotate the worm shaft but also to disengage the locked teeth.

[0004] To solve this problem, clearances can be provided between the inner surface of the worm shaft's coupling hole and the coupling section of the drive shaft, both circumferentially and radially. In a case where such clearances are provided, when the drive shaft begins to rotate from its coupled state in the reverse direction, it rotates freely for a certain period. During this time, the drive shaft acquires an inertial force or torque. After rotating freely due to the clearances, the drive shaft, under the inertial force, impacts the inner surface of the worm shaft's coupling hole with considerable force. This effectively disengages the coupled teeth of the worm shaft and the worm gear.

[0005] State of the art document: JP 2009-011077A

[0006] In the motor described above, clearances are formed in the circumferential and radial directions between the inner surface of the worm shaft coupling hole and the rotary shaft coupling section. Therefore, when the motor is operating, the worm shaft can move uncontrollably in the circumferential and radial directions due to, for example, inaccurate alignment. Uncontrollable movement of the worm shaft can cause the inner surface of the coupling hole to strike the coupling projection, resulting in noise.

[0007] Further engines are disclosed in DE 601 21 643 T2 and US 2002 / 0 158 527 A1.

[0008] Accordingly, one of the purposes of the present disclosure is to provide a motor that suppresses the noise generated by uncontrollable movements of the worm shaft.

[0009] According to one aspect of the present disclosure, a motor is provided comprising a motor body with a rotating shaft, a speed reduction mechanism including a worm shaft and a worm wheel engaging with the worm shaft, and a coupling section having a coupling hole and coupling the rotating shaft and the worm shaft to each other such that the rotating shaft and the worm shaft are rotatable together. The coupling section is rotatably provided together with one of the rotating shaft and the worm shaft. A coupling projection is provided on the other of the rotating shaft and the worm shaft. The coupling projection is inserted into the coupling hole. A circumferential clearance, which is a clearance in a circumferential direction, and a radial clearance, which is a clearance in a radial direction, are formed between an inner surface of the coupling hole and the coupling projection.A large buffer section is located in the large free space.

[0010] A radial buffer section is located in the radial clearance. The inner surface of the coupling hole and the coupling projection are configured to allow them to contact each other circumferentially, while compressing and deforming the circumferential buffer section when the motor body is driven to rotate the shaft.

[0011] In this configuration, the circumferential buffer section and the radial buffer section are each positioned within the circumferential and radial clearances between the inner surface of the coupling hole and the coupling projection. This reduces uncontrollable movement of the worm shaft during rotation. Consequently, the noise caused by the coupling hole inner surface striking the coupling projection is suppressed. Furthermore, when the rotating shaft is driven to rotate in the reverse direction—that is, when the rotating shaft begins to rotate in the reverse direction with the worm shaft connected to the worm wheel—the rotating shaft compresses and deforms the circumferential buffer section between the coupling hole inner surface and the coupling projection. During this time, the rotating shaft acquires inertial force or torque.Subsequently, with the circumferential buffer section compressed, the inner surface of the coupling hole and the coupling projection contact each other circumferentially while receiving the inertial force of the rotating shaft. This disengages the worm shaft and worm wheel, which were previously connected. According to this configuration, as described above, the circumferential buffer section and the radial buffer section suppress uncontrolled movements of the worm shaft, while the inertial force of the rotating shaft is ensured by utilizing the clearance between the coupling projection and the inner surface of the coupling hole.

[0012] According to one embodiment of the disclosure, the rotary shaft and the worm shaft are made of metal, and the coupling section is a plastic element formed separately from the rotary shaft and the worm shaft.

[0013] In this configuration, the inner surface of the coupling hole, into which the coupling projection of the worm shaft or the rotary shaft is inserted, is also made of plastic. Therefore, when the motor body rotates the rotary shaft, noise caused by the inner surface of the coupling hole striking the coupling projection in the circumferential direction is suppressed. This further reduces noise generation.

[0014] According to one embodiment of the disclosure, the circumferential buffer section and the radial buffer section are provided in the coupling section.

[0015] According to this configuration, the circumferential buffer section and the radial buffer section are formed in the coupling element, which is a plastic element separate from the rotary shaft and the worm shaft. The circumferential buffer section and the radial buffer section can therefore be designed as follows.

[0016] According to one embodiment of the disclosure, the circumferential buffer section and the radial buffer section are made of rubber.

[0017] According to this configuration, since the circumferential buffer section and the radial buffer section are made of rubber, uncontrollable movements of the worm shaft are suppressed in a favorable manner.

[0018] According to one embodiment of the disclosure, an axial buffer section is located between the coupling projection and a bottom surface of the coupling hole in the axial direction.

[0019] According to this configuration, due to the characteristics of the worm shaft and worm gear of the speed reduction mechanism, the reversal of the worm shaft's rotation generates a load in the axial direction. This load can cause the coupling projection to strike the bottom surface of the coupling hole in the axial direction, or it can cause the worm shaft to strike the rotating shaft in the axial direction. However, such potential axial impact is suppressed by the axial buffer section. Consequently, the noise generated by such impact is also suppressed.

[0020] According to one embodiment of the disclosure, the rotary shaft and the worm shaft are made of metal. The coupling section is a plastic element formed separately from the rotary shaft and the worm shaft, and the axial buffer section is provided within the coupling section.

[0021] According to this configuration, the axial buffer section is formed in the coupling element, which is a plastic element separate from the rotating shaft and the worm shaft. The axial buffer section can therefore be designed with a low profile.

[0022] According to one interpretation of the disclosure, the axial buffer section is made of rubber.

[0023] According to this configuration, since the axial buffer section is made of rubber, it prevents the coupling projection from striking the bottom surface of the coupling hole in the axial direction, and it favorably prevents the worm shaft from striking the rotating shaft in the axial direction.

[0024] The drawings show: Fig. 1. A cross-sectional view of an engine; Fig. 2A A top view of a joint as seen from a worm shaft; Fig. 2B a cross-sectional view of the joint; and Fig. 3. An example of a top view of the engine in operation.

[0025] A preferred embodiment according to the present disclosure is described below.

[0026] An engine 1, which is in Fig. The motor 1, shown in Figure 1, is used, for example, as a drive source for a windshield wiper device (not shown) attached to a vehicle. The motor 1 comprises a motor body 2 and a speed reduction section 3, which reduces the speed and increases the torque of the output rotation of the motor body 2 and transmits the rotation to the windshield wiper device.

[0027] The motor body 2 also includes a yoke 4 as a yoke housing. The yoke 4 is made of conductive material and is shaped as a cylinder with a closed end. A flange 4b ​​is formed at the opening 4a of the yoke 4. The speed reduction section 3 includes a housing 6. The flange 4b ​​is coupled to and attached to a mounting section 6a of the gearbox housing 6 by means of two bolts B.

[0028] A brush holder 5, made of an insulating material such as plastic, is attached to the opening 4a of the yoke 4 to close the opening 4a. When the yoke 4 and the gearbox housing 6 are fastened together with the bolts B, the brush holder 5 is held tightly by the flange 4b ​​and the mounting section 6a of the gearbox housing 6.

[0029] Magnets MG are attached to the inner surface of the yoke 4 such that they face each other. An armature (rotor) 7 is rotatably mounted inwards between the facing magnets MG. A rotating shaft 8 is attached to the armature 7. The proximal end of the rotating shaft 8 is rotatably supported by a bearing 9a, which is provided on the inner base of the yoke 4. A bearing 9b is mounted at a central position of the brush holder 5 to rotatably support the distal end of the rotating shaft 8, which projects into the gearbox housing 6.

[0030] The brush holder 5 holds a pair of feed brushes 5a. The brushes 5a are configured to slide along segments SG of a commutator 7a of the armature 7 to supply currents to the segments SG. The brush holder 5 has a connector section 5b that can be connected to an external connector (not shown). Currents from the external connector are supplied to the brushes 5a via terminals 5c provided in the connector section 5b.

[0031] The speed reduction section 3 contains the gearbox housing 6 and a speed reduction mechanism 11, which is housed in the gearbox housing 6. A pivot mounting section 12 is formed in the gearbox housing 6 at the mounting section 6a, which is attached to the yoke 4. The pivot mounting section 12 has an opening facing the yoke 4. The gearbox housing 6 has a worm shaft mounting section 13 and a worm gear mounting section 14. The worm shaft mounting section 13 extends from the pivot mounting section 12 along an axis L1 of the drive shaft 8 and in the opposite direction to the yoke 4. The worm gear mounting section 14 is located next to the worm shaft mounting section 13, or, when viewed from the outside, Fig. 1 on the bottom side.

[0032] The rotating shaft 8 passes through the brush holder 5 and has a distal end 8a that projects into the joint receiving section 12. The joint receiving section 12 receives a joint 16. The joint 16 is a coupling section that connects the distal end 8a of the rotating shaft 8 and a worm shaft 15, which is received in the worm shaft receiving section 13.

[0033] The worm shaft 15 is arranged such that it is coaxial with the rotating shaft 8. The worm shaft 15 has a proximal end which, when viewed in Fig. 1 is located at the right end and is connected to the joint 16. At the proximal end, i.e., near a coupling projection 15a, which will be discussed later, the worm shaft 15 is rotatably supported by a bearing 17a provided in the gearbox housing 6. The distal end of the worm shaft 15 is rotatably supported by a bearing 17b provided in the worm shaft receiving section 13. The worm shaft 15 has a helical worm section 15b formed at the central section in the axial direction, or at a partial section between the bearings 17a and 17b. The worm shaft receiving section 13 has a thrust plate 17c at one closed end in the axial direction. The thrust plate 17c absorbs the thrust load of the worm shaft 15.

[0034] The interior of the worm shaft receiving section 13 is connected to the interior of the worm gear receiving section 14. The worm gear receiving section 14 rotatably receives a disk-shaped worm gear 18 within it. The worm gear 18 engages with the worm section 15b. The axis of the worm gear 18 runs perpendicular to the axis of the worm shaft 15 or in a path perpendicular to the path of Fig. 1. The worm gear 18 and the worm shaft 15 form the speed reduction mechanism 11. An output shaft 19 is provided in the radial center of the worm gear 18 such that it is rotatable together with the output shaft 19, so that the output shaft 19 runs along the axis of the worm gear 18. The output shaft 19 has a distal end that is coupled to the windshield wiper assembly.

[0035] In the following, the joint 16, which couples the rotary shaft 8 of the motor body 2 and the worm shaft 15 of the speed reduction section 3, is described with reference to Fig. 2A and Fig. 2B described. As in Fig. As shown in Figure 2B, the joint 16 has a plastic section 20, which is attached to the distal end 8a of the rotating shaft 8 for rotation with the rotating shaft 8, first rubber links 21 and second rubber links 22a, 22b. The first and second rubber links 21, 22a, 22b are formed integrally with the plastic section 20 by means of two-color molds.

[0036] The plastic section 20 has a substantially cylindrical mounting section 23, which is attached to the distal end 8a of the rotating shaft 8. The distal end 8a of the rotating shaft 8 has a flat shape with a pair of parallel surfaces. The distal end 8a is pressed into a press-fit hole 24, which is designed such that it extends axially through a central section of the mounting section 23.

[0037] The mounting section 23 has a pair of rubber receiving holes 25 arranged around or radially outside the press-fit hole 24. The rubber receiving holes 25 are arranged at 180-degree intervals in the circumferential direction. Each rubber receiving hole 25 has one of the first rubber members 21. An end of each first rubber member 21 that is closer to the worm shaft 15 serves as a projection 21a, which extends axially from an end face 23a of the mounting section 23 that is close to the worm shaft 15. The end face 23a is a bottom face of the coupling hole 28 in the axial direction. The first rubber members 21 are axial buffer sections that absorb the load in the axial direction that is transferred by the worm shaft 15 to the motor body 2. Each first rubber element 21 has a step section 21b at its ends in the axial direction.The step sections 21b engage with the rubber receiving hole 25 in the axial direction to prevent the first rubber element 21 from detaching in the axial direction.

[0038] A worm shaft coupling section 26 is formed integrally within a portion of the mounting section 23 that is close to the worm shaft 15. The worm shaft coupling section 26 has a cylindrical shape with a diameter larger than that of the mounting section 23. In this embodiment, this means that the small-diameter plastic section 20 and the large-diameter worm shaft coupling section 26 form a single plastic element extending along the axis L1. A flange section 27 is formed at an axial end of the worm shaft coupling section 26 that is close to the motor body 2.

[0039] As in Fig. As shown in Figure 2A, a coupling hole 28 is formed in a central section of the worm shaft coupling section 26. The coupling hole 28 receives the coupling projection 15a, which is formed at the proximal end of the worm shaft 15. The coupling projection 15a of the worm shaft 15 has a flat shape with parallel surfaces 15x, 15y extending along the axis L1. The coupling projection 15a has longitudinal end surfaces 15c, 15d that bulge radially outwards and are located between the flat surfaces 15x, 15y. In contrast, the inner surface of the coupling hole 28 of the worm shaft coupling section 26 has an elongated shape that, when viewed in the axial direction, is slightly larger than the shape of the coupling projection 15a. This means that the inner surface of the coupling hole 28 has a flattened shape that is symmetrical about the axis L1.Clearances C1, C2 are formed between the inner surface of the coupling hole 28 and the coupling projection 15a. In particular, circumferential clearances C1 are formed between the inner surface of the coupling hole 28 and the flat surfaces 15x, 15y, while clearances C2 are formed between the inner surfaces of the coupling hole 28 and the longitudinal end surfaces 15c, 15d at the longitudinal ends of the coupling projection 15a.

[0040] The worm shaft coupling section 26 has the second rubber elements 22a, 22b, which are embedded by two-color molds. Each of the second rubber elements 22a, 22b is formed by a circumferential buffer section 31, a radial buffer section 32, and a coupling section 33 that couples the buffer sections 31, 32 together. The second rubber elements 22a, 22b are symmetrical with respect to the axis L1.

[0041] The circumferential buffer section 31 of each of the second buffer members 22a, 22b has a recess 28a formed by radially cutting outwards from the inner surface of the coupling hole 28. The inner surface of the coupling hole 28 contains contact sections 28b, 28e on both sides of the circumferential buffer section 31 of the second rubber member 22a and contact sections 28d, 28c on both sides of the circumferential buffer section 31 of the second rubber member 22b. Contact section 28b and contact section 28c are symmetrical about the axis L1, and contact section 28d and contact section 28e are symmetrical about the axis L1. A portion of the circumferential buffer section 31 projects radially inwards from the recess 28a. In the state described in Fig. As shown in Figure 2A, when the motor 1 is not in operation, the circumferential buffer sections 31 of the second rubber elements 22a, 22b touch the flat surfaces 15x, 15y of the coupling projection 15a at two positions that are symmetrical about the axis L1 of the worm shaft 15. That is to say, in Fig. 2A The circumferential buffer section 31 of the left-hand second rubber member 22a touches the flat surface 15x at two positions with the axis L1 between them, and the right-hand second rubber member 22b touches the flat surface 15y at two faces with the axis L1 between them. The two positions where one of the circumferential buffer sections 31 touches the flat surface 15x, and the two positions where the other circumferential buffer section 31 touches the flat surface 15y, are symmetrical about the axis L1.

[0042] The radial buffer sections 32 of the second rubber members 22a, 22b project radially inwards from the inner surface of the coupling hole 28 and contact the longitudinal end surfaces 15c, 15d of the coupling projection 15a. A contact surface 32a of each radial buffer section 32 contacts the coupling projection 15a and projects radially inwards in an arc. As described above, in a direction perpendicular to the axis, i.e., in the plane of the path of Fig. 2A, the coupling section 15a of the worm shaft 15 is supported by the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber members 22a, 22b from four directions, i.e. from both sides in the longitudinal direction and from both sides in the transverse direction.

[0043] Each of the second rubber links 22a, 22b contains an engagement section 34 that extends axially through the worm shaft coupling section 26 and engages with the coupling section 26 in the axial direction. The engagement sections 34 prevent the second rubber links 22a, 22b from falling off in the axial direction towards the worm shaft 15.

[0044] The working method of the present embodiment will now be described.

[0045] When the motor body 2 rotates the rotating shaft 8, for example in the forward direction, i.e. clockwise when viewed from Fig. 2A, drives, rotates the joint 16 together with the rotary shaft 8. Then the circumferential buffer section 31 of the second rubber member 22a, which contacts the flat surface 15x of the coupling projection 15a of the worm shaft 15, and the circumferential buffer section 31 of the second rubber member 22b, which contacts the flat surface 15y of the coupling section 15a, are compressed and deformed in the circumferential direction by the rotary driving force of the joint 16, i.e. the rotary shaft 8, as shown in Fig.Figure 3 shows that when the load on the output shaft 19 reaches or exceeds a predetermined value, the contact sections 28b, 28c on the inner surfaces of the coupling hole 28 each contact the flat surfaces 15x, 15y of the coupling section 15a in the circumferential direction, so that the rotation of the joint 16 is transmitted to the coupling projection 15a. This causes the rotary shaft 8, the joint 16, and the worm shaft 15 to rotate together, and the rotation of the worm shaft 15 is transmitted to the worm wheel 18. In the rotating state, because the coupling projection 15a of the worm shaft 15 is contacted and held by the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber elements 22a, 22b, the worm shaft 15 is prevented from rotating due to, for example, B. due to inaccurate alignment, it moves uncontrollably in directions perpendicular to the axis.

[0046] If the load on the output shaft 19 is less than the specified value, the rotation of the joint 16 is transmitted to the coupling projection 15a of the worm shaft 15 without the contact sections 28b, 28c on the inner surface of the coupling hole 28 touching the flat surfaces 15x, 15y of the coupling projection 15a. This means that in this case, the rotation of the joint 16 is transmitted to the coupling projection 15a via the circumferential buffer sections 31 of the second rubber elements 22a, 22b, so that the rotary shaft 8, the joint 16, and the worm shaft 15 rotate together. In this rotational state, the fact that the coupling projection 15a of the worm shaft 15 is touched and held by the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber elements 22a, 22b also prevents the worm shaft 15 from moving uncontrollably in directions perpendicular to the axis due to, for example, inaccurate alignment.

[0047] The motor 1 is configured such that when the contact sections 28b, 28c of the coupling hole 28 touch the flat surfaces 15x, 15y of the coupling projection 15a, the circumferential center line 12 of the radial buffer section 32 of the second rubber member 22a does not extend beyond a corner 35a defined by the flat surface 15y and the longitudinal end face 15c of the coupling projection 15a in the forward direction of rotation. The same applies to the radial buffer section 32 of the other second rubber member 22b. That is, the motor 1 is configured such that the circumferential center line L2 of the radial buffer section 32 does not extend beyond a corner 35b defined by the flat surface 15x and the longitudinal end face 15d of the coupling projection 15a in the forward direction. Corner 35a and corner 35b are arranged in symmetrical positions with respect to axis L1.Motor 1 is configured to operate in the same manner when the rotary shaft 8 and the joint 16 rotate in the reverse direction. Accordingly, when the rotary shaft 8, the joint 16, and the worm shaft 15 rotate together, the radial buffer sections 32 of the second rubber links 22a, 22b are prevented from disengaging from the coupling projection 15a. Consequently, for example, the coupling projection 15a prevents the radial buffer sections 32 from being engaged, which would occur if they were to disengage.

[0048] As described above, when a state in which the rotary shaft 8 and the speed reduction mechanism 11 rotate in the forward direction is changed, for example, to a state in which the load on the output shaft 19 stops, i.e., the rotary shaft 8 is locked, the worm section 15b of the worm shaft 15 and the teeth of the worm wheel 18 can be engaged. If the rotary shaft 8 is rotated in the reverse direction in this state, the joint 16 rotates in the reverse direction so that the contact section 28d of the coupling hole 28 touches the flat surface 15y of the coupling section 15a and the contact section 28e of the coupling hole 28 touches the flat surface 15x of the coupling projection 15a. At the time when the contact sections 28d, 28e touch the flat surfaces 15y, 15x, the rotating shaft 8 and the joint 16 gain rotational inertia.This disengages the teeth of the worm shaft 15 and the teeth of the worm wheel 18, which are connected to each other, in a favorable manner. Likewise, when the rotary shaft 8 rotates in the forward direction after having been stopped while rotating in the reverse direction, the teeth of the worm shaft 15 and the teeth of the worm wheel 18, which are connected to each other, are disengaged from each other in a favorable manner. As described above, according to the present embodiment, the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber elements 22a, 22b prevent the worm shaft 15 from moving uncontrollably, and the inertial force of the rotary shaft 8 is ensured by the circumferential clearances C1 and the radial clearances C2 between the coupling projection 15a and the inner surface of the coupling hole 28.

[0049] In the present embodiment, due to the characteristics of the worm shaft 15 and the worm wheel 18, a reversal of rotation of the worm shaft 15 generates a load in the axial direction. This load, acting towards the motor body 2 and absorbed by the worm shaft 15, is absorbed by the projections 21a of the first rubber elements 21, which contact the coupling section 15a of the worm shaft 15 in the axial direction. Therefore, the first rubber elements 21 prevent the coupling projection 15a from impacting the bottom surface of the coupling hole 28 in the radial direction, i.e., the end surface 23a of the mounting section 23, which is close to the worm shaft 15, and from impacting the coupling section 15a against the distal end 8a of the rotating shaft 8. Consequently, the noise generated by such impacts is prevented.

[0050] The present embodiment has the following advantages.(1) The joint is rotatable with the rotating shaft. The joint has the coupling hole into which the coupling projection of the worm shaft is inserted, such that the coupling section has the circumferential clearances C1 and the radial clearances C2. The circumferential buffer sections and the radial buffer sections are located in the circumferential clearances C1 and the radial clearances C2, respectively, between the inner surfaces of the coupling hole and the coupling projection. The motor is configured such that, when the rotating shaft is turned through the motor body, the inner surface of the coupling hole and the coupling section compress and deform the circumferential buffer sections while in circumferential contact with each other. This reduces uncontrollable movement of the worm shaft when the motor is running and stopped.As a result, noise caused by the inner surface of the coupling hole striking the coupling projection is suppressed. Furthermore, when the drive shaft is driven to rotate in the reverse direction, with the worm shaft connected to the worm gear—that is, when the drive shaft begins to rotate in the reverse direction—the drive shaft rotates while compressing and deforming the circumferential buffer sections between the inner surface of the coupling hole and the coupling section. During this process, the inertial force, or torque, of the drive shaft is acquired. Subsequently, while the circumferential buffer sections are compressed, the inner surface of the coupling hole and the coupling section contact each other circumferentially while absorbing the inertial force of the drive shaft. This disengages the teeth of the worm shaft and the teeth of the worm gear, which were previously engaged.As described above, according to the present embodiment, the circumferential buffer sections and the radial buffer sections prevent the worm shaft from moving uncontrollably, and the inertial force of the rotating shaft is ensured by the circumferential clearances C1 and the radial clearances C2 between the coupling projection and the inner surface of the coupling hole. (2) The rotary shaft and the worm shaft are made of metal, and the joint is made of plastic and is formed separately from the rotary shaft and the worm shaft. Accordingly, the inner surface of the coupling hole, into which the coupling section of the worm shaft is inserted, is made of plastic. Therefore, when the motor body rotates the rotary shaft, noise caused by the inner surface of the coupling hole striking the coupling projection in the circumferential direction is suppressed. This further reduces noise. (3) The circumferential buffer sections and the radial buffer sections are provided in the joint, which is a plastic link separate from the rotary shaft and the worm shaft. The circumferential buffer sections and the radial buffer sections are therefore lightweight. (4) Since the circumferential buffer sections and the radial buffer sections are made of rubber, it is advantageously prevented that the worm shaft moves uncontrollably. (5) The first rubber links are located between the coupling projection and the bottom surface of the coupling hole in the axial direction, i.e., the end surface of the mounting section that is close to the worm shaft. Reversal of the worm shaft's rotation creates a load in the axial direction. This load can cause the coupling projection of the worm shaft to strike the end surface of the mounting section that is close to the rotating shaft and its distal end. However, such potential impact is suppressed by the first rubber links. Consequently, noise generated by such impact is also suppressed. (6) The joint, which is a plastic link separate from the rotary shaft and the worm shaft, has the first rubber links. The first rubber links are therefore lightweight. (7) Since the first rubber links are made of rubber, it is advantageously prevented that the coupling projection strikes the bottom surface of the coupling hole in the axial direction, and that the coupling projection strikes the distal end of the rotating shaft in the axial direction. (8) The circumferential buffer sections are located radially inward from the contact sections 28b, 28c, 28d, 28e on the inner surface of the coupling hole, which contact the coupling projection. According to this configuration, it is possible to ensure the space for the circumferential buffer sections while maintaining the length of the arms for torque transmission from the rotary shaft to the worm shaft, i.e., while maintaining a long dimension between the axis L1 of the rotary shaft and the contact sections 28b, 28c, 28d, 28e.

[0051] The embodiments of the present disclosure can be modified as follows.

[0052] In the embodiment shown above, the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber elements 22a, 22b are connected to each other by the coupling sections 33. However, the circumferential buffer sections 31 and the radial buffer sections 32 can be formed separately from each other.

[0053] In the embodiment shown above, the circumferential buffer sections 31 and the radial buffer sections 32 of the second rubber elements 22a, 22b are provided in the joint 16. That is, the circumferential buffer sections 31 and the radial buffer sections 32 are supported by the rotating shaft 8. In a modification, the circumferential buffer sections 31 and the radial buffer sections 32 can be formed on the flat surfaces 15x, 15y of the coupling section 15a of the worm shaft 15. That is, the circumferential buffer sections 31 and the radial buffer sections 32 can be supported by the worm shaft 15.

[0054] In the embodiment shown above, the first rubber elements 21 are supported by the rotating shaft 8. That is, the first rubber elements 21 are provided on the plastic section 20, which is arranged around the distal end 8a of the rotating shaft 8. In a modification, the first rubber elements 21 can be supported by the worm shaft 15. For example, the first rubber elements 21 can be formed on an axial end face of the coupling projection 15a of the worm shaft 15.

[0055] In the embodiment shown above, the plastic section 20 of the joint 16 is attached to the rotating shaft 8, and the coupling projection 15a of the worm shaft 15 is inserted into the coupling hole 28 of the plastic section 20. However, in a modification, the relationship can be reversed. That is, the plastic section 20 can be attached to the worm shaft 15, and the distal end 8a of the rotating shaft 8 can be used as a coupling projection that is inserted into the coupling hole 28 of the plastic section 20.

[0056] In the embodiment described above, the joint 16 has the plastic section 20, which is separate from the metal rotating shaft 8, and the plastic section 20 is attached to the rotating shaft 8. The embodiment is not limited to this configuration. In one modification, the joint 16 can be made of the same material as the rotating shaft 8 and formed integrally with it. Furthermore, the joint 16, which functions as a coupling section, can be provided within the worm shaft 15. The joint 16 can be made of the same material as the worm shaft 15 and formed integrally with it. Reference symbol list 1 engine 2 engine bodies 8 Rotary shaft 11 Speed ​​reduction mechanism 15 worm shaft 15a Coupling projection 16 Joint as coupling section 18 worm gear 29 Plastic section 21 first rubber sections (axial buffer sections) 22a, 22b second rubber sections 28 coupling holes 31 extensive buffer sections 32 axial buffer sections C1 extensive open spaces C2 radial clearances

Claims

[1] Motor (1), comprising: a motor body (2) with a rotating shaft (8); a speed reduction mechanism (11) comprising a worm shaft (15) and a worm wheel (18), which engages with the worm shaft (15); and a coupling section (16) which has a coupling hole (28) and couples the rotary shaft (8) and the worm shaft (15) together in such a way that the rotary shaft (8) and the worm shaft (15) can be rotated together, wherein the coupling section (16) is rotatable together with one of the rotary shaft (8) and the worm shaft (15), and one coupling projection (8a, 15a) is rotatable together with the other of the rotary shaft (8) and the worm shaft (15), wherein the coupling projection (8a, 15a) is inserted into the coupling hole (28), wherein a contact section (28b-28e) is provided on an inner surface of the coupling hole (28) and wherein the contact section (28b-28e) is configured such that that it can touch the coupling projection (8a, 15a) in a circumferential direction when the motor body (2) is driven to rotate the rotating shaft (8), wherein a circumferential clearance (C1), which is a clearance in the circumferential direction, and a radial clearance (C2), which is a clearance in a radial direction, between the inner surface of the coupling hole (28) and the coupling projection (8a, 15a) is formed, wherein a circumferential buffer section (31) is located in the circumferential free space, wherein a radial buffer section (32) is located in the radial free space, and wherein the contact section (28b-28e) of the coupling hole (28) and the coupling projection (8a, 15a) are configured such that they can directly touch each other in the circumferential direction while compressing and deforming the circumferential buffer section (31) in the circumferential direction when the motor body (2) is driven to rotate the rotating shaft (8). [2] Motor (1) according to claim 1, wherein the rotary shaft (8) and the worm shaft (15) are made of metal, and the coupling section (16) is a plastic element that is formed separately from the rotary shaft (8) and the worm shaft (15). [3] Motor (1) according to claim 2, wherein the circumferential buffer section (31) and the radial buffer section (32) are provided in the coupling section (16). [4] Motor (1) according to one of claims 1 to 3, wherein the circumferential buffer section (31) and the radial buffer section (32) are made of rubber. [5] Motor (1) according to one of claims 1 to 4, wherein an axial buffer section is located between the coupling projection (8a, 15a) and a bottom surface of the coupling hole (28) in the axial direction. [6] Motor (1) according to claim 5, wherein the rotary shaft (8) and the worm shaft (15) are made of metal, the coupling section (16) is a plastic element that is formed separately from the rotary shaft (8) and the worm shaft (15), and the axial buffer section is provided in the coupling section (16). [7] Motor (1) according to one of claims 5 or 6, wherein the axial buffer section is made of rubber. [8] Motor (1) according to any one of claims 1 to 7, wherein the circumferential buffer section (31) is located radially inwards from the contact section (28b-28e) of the coupling hole (28).

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