JP6435746B2 - Thrust receiving structure and motor - Google Patents

Description

  The present invention relates to a thrust receiving structure and a motor.

  Conventionally, as a structure for receiving a thrust load of a rotating shaft, for example, as disclosed in FIG. 10 of Patent Document 1, a thrust receiving ball is provided in an accommodation recess on an axial end face of the rotating shaft (worm shaft in Patent Document 1). There is something that provided. In such a configuration, the thrust receiving ball rotates in the receiving recess while receiving a thrust load, and wear of the thrust receiving ball is suppressed to a small extent. Further, when the thrust receiving ball is assembled, the thrust receiving ball is held in the receiving recess by the viscosity of a lubricant such as grease injected into the receiving recess.

JP 2013-46522 A

  In the above thrust receiving structure, in order to make the thrust receiving ball pivotable as described above, it is necessary to set a clearance between the ball and the inner wall surface of the housing recess. For this reason, at the time of assembly, the thrust receiving ball easily falls off from the receiving recess, and it is difficult to hold the thrust receiving ball in the receiving recess only by the viscosity of the lubricant. In addition, since the thrust receiving ball is a small part, it is difficult to assemble the thrust receiving ball in the housing recess, and there is room for improvement in terms of assembly.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a thrust receiving structure and a motor capable of improving the assembling property of a thrust receiving ball.

A thrust receiving structure that solves the above-described problem includes a thrust shaft including a rotating shaft and a thrust receiving ball that is provided at one end of the rotating shaft and is rotatably accommodated in a receiving recess into which a lubricant is injected. A thrust receiving structure comprising a rotating shaft and a thrust receiving ball made of a magnetic material rotatably accommodated in a receiving recess provided at one end of the rotating shaft , wherein the rotating shaft Includes a magnet member that magnetically holds the thrust receiving ball in the receiving recess, and the thrust receiving ball is held in the receiving recess by the magnetism of the magnet member. In addition to being interposed between the bottom surface of the recess and the thrust receiving ball, a clearance is set between the outer surface of the magnet member and the inner wall surface of the housing recess .

  According to this configuration, while the clearance is set between the thrust receiving ball and the inner wall surface of the receiving recess so that the thrust receiving ball can be rotated, the ball falls off from the receiving recess during assembly. It can be suppressed by magnetic force. Further, when the thrust receiving ball is assembled into the receiving recess, the ball is attracted to the receiving recess by magnetic force, so that the thrust receiving ball, which is a small component, can be easily assembled into the receiving recess.

Further , the thrust receiving ball can be held in the housing recess by the magnet member.

Further , since the magnet member that holds the thrust receiving ball is disposed on the bottom surface of the receiving recess, it is possible to suitably suppress the drop of the thrust receiving ball from the receiving recess.

In the thrust receiving structure, the magnet member is preferably formed by magnetizing a steel material harder than the material of the rotating shaft.
According to this configuration, since the magnet member that is in axial contact with the thrust receiving ball is made of a steel material that is harder than the material of the rotating shaft, it is possible to suppress wear and breakage of the magnet member. High thrust receiving structure can be constructed.

In the thrust receiving structure, it is preferable that a sliding receiving plate made of a magnetic material is interposed between the magnet member and the thrust receiving ball.
According to this configuration, while the thrust receiving ball is held in the housing recess by the magnetic force of the magnet member, the ball and the magnet member are not in direct contact via the slide receiving plate between the ball and the magnet member. Can be configured. Therefore, wear and breakage of the magnet member can be suppressed, and a reliable thrust receiving structure can be constructed even when an inexpensive magnet (such as a ferrite magnet) having relatively low rigidity is used as the magnet member.

In the thrust receiving structure, a clearance is set between the outer surface of the sliding receiving plate and the inner wall surface of the receiving recess.

In the thrust receiving structure, it is preferable that the inner peripheral surface of the housing recess has a tapered shape that expands toward the opening side.
According to this configuration, since the inner peripheral surface of the housing recess has a tapered shape that expands toward the opening side, the thrust receiving ball can be more easily assembled to the housing recess.

In the thrust receiving structure, it is preferable that at least a part of the thrust receiving ball is magnetized.
According to this configuration, since at least a part of the thrust receiving ball is magnetized, the thrust receiving ball can be held in the housing recess by its own magnetic force.

  In the thrust receiving structure, the thrust receiving ball is configured to contact a shaft end portion of a second rotating shaft that is rotationally connected to the rotating shaft and to receive a thrust load from the second rotating shaft. It is preferable.

  According to this configuration, a thrust receiving structure in which a thrust receiving ball is disposed between two axes is constructed. Here, when an axial misalignment occurs between the two shafts, the thrust receiving ball is likely to drop out of the receiving recess, but the situation is because the thrust receiving ball is held in the receiving recess by magnetism. In this case, the thrust receiving ball is less likely to drop off, and a more reliable thrust receiving structure can be constructed.

In the thrust receiving structure, the thrust receiving ball is partially protruded from the receiving recess, and the protruding portion of the thrust receiving ball is configured to abut the shaft end portion of the second rotating shaft.
A motor that solves the above problems is a motor that includes the thrust receiving structure described above.
According to this configuration, the assembling property of the thrust receiving ball in the thrust receiving structure is improved, and as a result, the assembling property of the motor can be improved.

The motor includes a motor main body having a drive shaft, and a speed reduction unit having a driven shaft that is coaxially arranged with the drive shaft and can rotate integrally with the drive shaft, and the drive shaft is rotationally coupled to the rotation shaft. The second rotating shaft or the rotating shaft, and the driven shaft is the rotating shaft or the second rotating shaft, and the thrust receiving structure is provided between the drive shaft and the driven shaft. It is preferable to provide.

  According to this configuration, when a radial misalignment occurs between the drive shaft and the driven shaft, the thrust receiving ball is likely to drop out of the receiving recess of the driven shaft (or drive shaft). Since the receiving ball is held in the receiving recess by magnetism, the thrust receiving ball is not easily dropped even in this situation, and a more reliable thrust receiving structure can be constructed.

  According to the thrust receiving structure and the motor of the present invention, it is possible to improve the assembling property of the thrust receiving ball.

It is a schematic diagram of the motor of the embodiment. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of the same form. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is sectional drawing which shows the connection part of the armature shaft and worm shaft of another example. It is the side view which looked at the worm shaft of the example from the base end side.

Hereinafter, an embodiment of the motor will be described.
As shown in FIG. 1, the motor of the present embodiment is configured to be able to transmit the rotation output of the motor body 11 to the speed reduction unit 13 via the rotation transmission unit 12.

  The motor main body 11 includes an armature 16 (an armature) having a metal armature shaft 15 in a yoke housing 14. The armature shaft 15 is pivotally supported by a pair of bearings 17 supported by the yoke housing 14. The yoke housing 14 is provided with a motor side thrust receiving portion 18 that receives a thrust load from the base end portion 15 a of the armature shaft 15. The thrust receiving portion 18 includes a plate 18 a supported by the yoke housing 14 and a ball 18 b interposed between the plate 18 a and the base end portion 15 a of the armature shaft 15. The ball 18b and the plate 18a support the base end portion 15a of the armature shaft 15 in the axial direction.

  The speed reduction unit 13 includes a worm shaft 22 (rotary shaft) made of a metal material (magnetic material) such as carbon steel and a worm wheel 23 meshing with the worm shaft 22 in a gear housing 21 assembled to the yoke housing 14. I have. The worm shaft 22 is pivotally supported at a position coaxial with the armature shaft 15 of the motor body 11 by a pair of bearings 24 a and 24 b supported by the gear housing 21. The worm shaft 22 is provided with a worm portion 22a between the bearings 24a and 24b. The worm wheel 23 is rotatably supported with respect to the gear housing 21 so as to mesh with the worm portion 22a, and is assembled to the central portion of the worm wheel 23 so that an output shaft (not shown) of the motor rotates integrally.

  Both the proximal end portion 22b of the worm shaft 22 and the distal end portion 15b of the armature shaft 15 have a two-sided width shape when viewed in the axial direction, and can be engaged with the rotation transmitting portion 12 accommodated in the gear housing 21 in the rotational direction. Respectively. Thus, the worm shaft 22 and the armature shaft 15 are connected to each other via the rotation transmission unit 12, and the rotation transmission unit 12 transmits the rotation of the armature shaft 15 to the worm shaft 22. The rotation of the worm shaft 22 is transmitted to the output shaft (not shown) of the motor via a worm wheel 23 that meshes with the worm portion 22a.

  Further, the gear housing 21 is provided with a speed reducing portion side thrust receiving portion 25 that receives a thrust load from the tip portion 22 c of the worm shaft 22. The thrust receiving portion 25 includes a plate 25 a supported by the gear housing 21 and a ball 25 b interposed between the plate 25 a and the tip portion 22 c of the worm shaft 22. A part of the ball 25b is fitted into a recess 22d that is recessed in the tip surface of the worm shaft 22, and a portion protruding from the recess 22d is in contact with the plate 25a. The plate 25a is configured such that the position in the axial direction can be adjusted, and a preload in the axial direction is applied to the tip portion 22c of the worm shaft 22 from the plate 25a.

Next, a connecting portion between the armature shaft 15 and the worm shaft 22 will be described.
As shown in FIG. 2, a housing recess 33 for housing the magnet member 31 and the thrust receiving ball 32 is formed in the shaft end surface (base end surface 22 e) on the base end portion 22 b side of the worm shaft 22. The housing recess 33 is circular when viewed in the axial direction, and the center line of the housing recess 33 is formed to coincide with the axis L of the worm shaft 22. Note that a lubricant such as grease (not shown) is injected into the housing recess 33.

  A disc-shaped magnet member 31 made of a steel material harder than the material of the worm shaft 22 is accommodated in the accommodating recess 33. The magnet member 31 is disposed such that its plate surface is orthogonal to the axis L of the worm shaft 22. In addition, the outer diameter of the magnet member 31 is set smaller than the diameter of the inner peripheral surface 33 a of the housing recess 33, and a clearance is set between the outer peripheral surface of the magnet member 31 and the inner peripheral surface 33 a of the housing recess 33. ing. One end surface in the axial direction of the magnet member 31 is in contact with the bottom surface 33 b of the housing recess 33, and the other end surface in the axial direction is in contact with a thrust receiving ball 32 partially accommodated in the housing recess 33.

  The thrust receiving ball 32 is made of a steel material (bearing steel). The thrust receiving ball 32 is configured such that a part of the thrust receiving ball 32 protrudes in the axial direction from the receiving recess 33, and the tip end surface of the armature shaft 15 (the shaft end surface of the tip end portion 15 b) is formed at the protruding portion of the thrust receiving ball 32. Abutted in the axial direction. That is, the thrust receiving ball 32 is interposed between the front end surface of the armature shaft 15 and the magnet member 31 in the axial direction. The diameter of the thrust receiving ball 32 is set smaller than the diameter of the inner peripheral surface 33 a of the receiving recess 33, and a clearance is set between the thrust receiving ball 32 and the inner peripheral surface 33 a of the receiving recess 33. .

  Here, the magnet member 31 is a member obtained by magnetizing a steel material, and is magnetized along the axial direction of the worm shaft 22 (that is, the N pole and the S pole are polarized in the axial direction of the worm shaft 22). As a result, in the magnet member 31, one end surface in the axial direction that contacts the bottom surface 33 b of the housing recess 33 becomes one pole (S pole in FIG. 2), and the other end surface in the axial direction that contacts the thrust receiving ball 32 is the other pole ( In FIG. 2, it is configured to have N poles).

  When assembling the magnet member 31 and the thrust receiving ball 32 into the housing recess 33 of the worm shaft 22, first, the magnet member 31 is inserted into the housing recess 33 and the magnetic force of the magnet member 31 itself against the bottom surface 33 b of the housing recess 33. Adsorb with. Thereafter, the thrust receiving ball 32 is held in the receiving recess 33 by magnetically attracting the thrust receiving ball 32 to the magnet member 31. The lubricant is injected into the housing recess 33 before (or after) the magnet member 31 is assembled.

Next, the operation of this embodiment will be described.
When the armature 16 of the motor body 11 is rotationally driven by power feeding, the rotation of the armature shaft 15 is transmitted to the worm shaft 22 via the rotation transmission unit 12, and the rotation of the worm shaft 22 is transmitted to the worm wheel 23. Here, when the rotation of the worm shaft 22 is transmitted to the worm wheel 23, a thrust force (stress in the axial direction) is generated in the worm shaft 22, but the armature shaft 15 and the worm shaft 22 have a motor side thrust receiver. Since the preload in the axial direction is applied from the portion 18 and the deceleration portion side thrust receiving portion 25, the backlash in the axial direction of the worm shaft 22 is suppressed. As a result, the generation of abnormal noise due to the backlash in the axial direction of the worm shaft 22 is suppressed.

  In the present embodiment, in order to reduce the manufacturing cost, a slight clearance is set between the worm shaft 22 and the bearings 24a and 24b in the radial direction so that various parts such as the worm shaft 22 and the bearings 24a and 24b can be used. High precision molding is unnecessary. For this reason, there is play in the worm shaft 22 in the radial direction, and the armature shaft 15 and the worm shaft 22 may rotate while the worm shaft 22 is inclined with respect to the armature shaft 15. At this time, the posture of the worm shaft 22 is stabilized by the action of the thrust receiving ball 32 interposed between the armature shaft 15 and the worm shaft 22, and the generation of noise and wear are suppressed. Yes.

  In the thrust receiving structure between the armature shaft 15 and the worm shaft 22, the worm shaft 22 is provided with play in the radial direction (that is, the worm shaft 22 is tiltable with respect to the armature shaft 15). ), When the worm shaft 22 tilts with respect to the armature shaft 15, the position of the receiving recess 33 with respect to the tip portion 15 b of the armature shaft 15 is shifted in the radial direction, and the thrust receiving ball 32 is likely to drop off. However, in the present embodiment, since the thrust receiving ball 32 is held in the receiving recess 33 by the magnetic force of the magnet member 31, the thrust receiving ball 32 is not easily dropped even in such a situation, and a highly reliable thrust receiving structure. Has been built. Further, in this embodiment, since the thrust receiving ball 32 partially protrudes from the receiving recess 33, the thrust receiving ball 32 by the magnetic force of the magnet member 31 is compared with the configuration in which the entire ball 32 is received in the receiving recess 33. The drop-off suppressing effect can be obtained more remarkably.

  Note that, as in the above embodiment, the thrust receiving ball 32 is partially protruded from the housing recess 33 and the protruding portion is used as a thrust receiving portion for the armature shaft 15, so that the front end surface of the armature shaft 15 and the worm shaft 22. An axial clearance is generated between the base end face 22e and the base end face 22e. Thereby, the interference between the armature shaft 15 and the worm shaft 22 is suppressed, and the generation of abnormal noise is suppressed. In particular, when the diameter of the distal end of the armature shaft 15 is set to be larger than the diameter of the housing recess 33, the thrust receiving ball 32 protrudes from the housing recess 33 and the distal end surface of the armature shaft 15 and the base end surface 22 e of the worm shaft 22 It is essential to provide a clearance between the armature shaft 15 and the worm shaft 22 as the projection amount of the thrust receiving ball 32 from the receiving recess 33 increases. As described above, a configuration in which a part of the thrust receiving ball 32 protrudes from the receiving recess 33 can be said to be a configuration in which the ball 32 is easily dropped from the receiving recess 33. However, as in the present embodiment, the thrust receiving ball 32 is made magnetic. By holding in the housing recess 33, the ball 32 can be stably held in the housing recess 33 while a part of the ball 32 protrudes from the housing recess 33.

Next, characteristic effects of the present embodiment will be described.
(1) The thrust receiving ball 32 is held in the accommodating recess 33 provided on the base end surface 22e of the worm shaft 22 by the magnetism of the magnet member 31 provided on the worm shaft 22 side. According to this configuration, while the clearance is set between the thrust receiving ball 32 and the inner peripheral surface 33a of the receiving recess 33 so that the thrust receiving ball 32 can be rotated, the ball 32 is received during assembly. It is possible to suppress the drop-off from the recess 33 by the magnetic force. Furthermore, when the thrust receiving ball 32 is assembled to the receiving recess 33, the thrust receiving ball 32 is attracted to the receiving recess 33 by the magnetic force of the magnet member 31, so that the thrust receiving ball 32, which is a small component, can be easily moved into the receiving recess 33. Can be assembled.

  In addition, since the magnet member 31 itself is magnetically attracted to the housing recess 33 by using the worm shaft 22 as a magnetic body, it is easy to assemble the magnet member 31 that is a small component like the thrust receiving ball 32.

  (2) The magnet member 31 is interposed between the bottom surface 33 b of the accommodating recess 33 and the thrust receiving ball 32. According to this configuration, the magnet member 31 that holds the thrust receiving ball 32 is disposed on the bottom surface 33 b of the receiving recess 33, so that the drop of the thrust receiving ball 32 from the receiving recess 33 can be suitably suppressed. Further, since the magnet member 31 is interposed between the thrust receiving ball 32 and the bottom surface 33 b of the receiving recess 33, the thrust receiving ball 32 can be configured not to directly contact the bottom surface 33 b of the receiving recess 33.

  Further, there has conventionally been a configuration in which a plate-like member (plate) is interposed between the bottom surface 33b of the accommodating recess 33 and the thrust receiving ball 32. In this embodiment, the plate-like member is magnetized to magnetize the thrust receiving ball 32. The magnet member 31 is used for adsorption. For this reason, since the conventional motor assembly equipment can be followed, an increase in manufacturing cost can be suppressed.

  (3) Since the magnet member 31 is configured by magnetizing a steel material that is harder than the material of the worm shaft 22, wear and breakage of the magnet member 31 that receives a thrust load together with the thrust receiving ball 32 can be suppressed. As a result, a highly reliable thrust receiving structure can be constructed.

  (4) The magnet member 31 is magnetized in the axial direction of the worm shaft 22. That is, since the magnet is magnetized in the direction in contact with the thrust receiving ball 32, the thrust receiving ball 32 can be suitably held by magnetism.

  Further, as in the present embodiment, when the clearance is set between the thrust receiving ball 32 and the magnet member 31 and the inner peripheral surface 33a of the housing recess 33, the clearance is reduced in the configuration in which the magnet member 31 is magnetized in the radial direction. Under the influence, the magnetic attraction force of the magnet member 31 to the thrust receiving ball 32 is reduced. In this respect, in the present embodiment, since the magnet member 31 is magnetized in the axial direction, the influence of the clearance can be reduced, and the thrust receiving ball 32 can be more securely held by magnetism.

  (5) The thrust receiving ball 32 is configured to receive a thrust load from the armature shaft 15 by coming into contact with the tip portion 15b of the armature shaft 15 that is rotationally connected to the worm shaft 22 via the rotation transmitting portion 12. The According to this configuration, when a radial misalignment occurs between the two shafts (between the worm shaft 22 and the armature shaft 15), the thrust receiving ball 32 is likely to drop out of the housing recess 33. Even in such a situation, the thrust receiving ball 32 is held in the housing recess 33 by magnetism, so that it is difficult to drop off, and a more reliable thrust receiving structure can be constructed.

In addition, you may change the said embodiment as follows.
In the above embodiment, as shown in FIG. 3, a slide receiving plate 41 made of a magnetic material is interposed between the axial direction of the magnet member 31 and the thrust receiving ball 32, and the rigidity of the magnet member 31 is relatively low. It may be changed to an inexpensive magnet (such as a ferrite magnet). The slide receiving plate 41 is obtained by heat-treating (quenching) a metal in advance, and has a higher rigidity than the material of the worm shaft 22.

  According to this configuration, while the thrust receiving ball 32 is held in the housing recess 33 by the magnetic force of the magnet member 31, the ball 32 and the magnet are interposed between the ball 32 and the magnet member 31 via the slide receiving plate 41. It can comprise so that the member 31 may not contact directly. Therefore, since wear and breakage of the magnet member 31 can be suppressed, an inexpensive magnet (ferrite magnet or the like) having a relatively low rigidity is used as the magnet member, while reducing costs, and a highly reliable thrust receiver. You can build a structure.

  In the embodiment described above, as shown in FIG. 4, the end surface of the magnet member 31 on the thrust receiving ball 32 side is formed with a concave portion 31a that is recessed in a spherical shape following the shape of the ball 32, and the ball 32 is formed in the concave portion 31a. You may comprise so that at least one part may enter. According to this configuration, the area where the magnet member 31 contacts the ball 32 can be increased compared to the configuration in which the contact surface of the magnet member 31 with the ball 32 is planar as in the above embodiment. Further, local wear of the magnet member 31 can be suppressed.

  In the above embodiment, as shown in FIG. 5, the inner peripheral surface 33 a of the accommodating recess 33 is formed with a tapered surface 33 c that increases in diameter toward the proximal end surface 22 e in the axial direction, and the thrust receiving ball 32 is a tapered surface. You may comprise so that it may contact | abut to the axial direction with respect to 33c. According to this configuration, since the inner peripheral surface 33a of the housing recess 33 has a tapered shape that expands toward the opening side (base end surface 22e side), the thrust receiving ball 32 can be easily assembled to the housing recess 33. . In addition, the formation of the tapered surface 33c makes it easy to assemble, but the thrust receiving ball 32 is likely to drop out of the housing recess 33, but this point can be supplemented by the magnetic force of the magnet member 31.

  In the above embodiment, as shown in FIG. 6, the groove 42 may be provided in the radially outer position of the housing recess 33 in the base end surface 22 e of the worm shaft 22. According to this configuration, since the groove portion 42 (gap) is interposed between the inner peripheral surface 33a of the housing recess 33 and the outer peripheral surface of the base end of the worm shaft 22, the magnet member 31 in the housing recess 33 is provided. The influence of the magnetism on the outer peripheral surface of the worm shaft 22 can be reduced by the groove portion 42. As a result, iron powder or the like can be prevented from adhering to the outer peripheral surface of the worm shaft 22. In particular, in the configuration in which the bearing 24a is disposed in the vicinity of the base end portion 22b of the worm shaft 22 as in the present embodiment, wear powder generated at the bearing 24a portion easily adheres to the outer peripheral surface of the worm shaft 22 base end. If the groove portion 42 is formed in such a configuration, the effect of suppressing adhesion of iron powder or the like to the outer peripheral surface of the worm shaft 22 becomes more remarkable.

  In the above embodiment, the magnet member 31 is interposed between the bottom surface 33b of the housing recess 33 and the thrust receiving ball 32. However, for example, as shown in FIG. You may provide so that it may be located in the outer peripheral side. In the example shown in the figure, the axial end surface 43 a of the magnet member 43 is flush with the base end surface 22 e of the worm shaft 22. Even with such a configuration, the same effect as the effect (1) of the above embodiment can be obtained. Further, according to this configuration, the magnet member 43 can be disposed at a position shallower than the magnet member 31 of the above-described embodiment that contacts the thrust receiving ball 32 in the axial direction (position on the base end face 22e side of the worm shaft 22). Therefore, it is possible to contribute to the improvement of the assembling property of the magnet member 43.

  In the above embodiment, a plate-like member (plate) interposed between the bottom surface 33 b of the accommodating recess 33 and the thrust receiving ball 32 is magnetized to form the magnet member 31, and the thrust receiving ball 32 is magnetized by the magnet member 31. Is configured to be held in the housing recess 33. However, the present invention is not particularly limited to this, and for example, as shown in FIG. 8, a configuration may be adopted in which a part of the thrust receiving ball 44 is magnetized.

  In the example of the figure, the thrust receiving ball 44 is composed of a spherical magnet portion 44a constituting the center portion and an outer shell portion 44b covering the magnet portion 44a, and the outer shell portion 44b is more than resin or magnet portion 44a. It is made of nonmagnetic metal with high rigidity. Further, in the example of the figure, a hard thrust receiving plate 45 is interposed between the bottom surface 33 b of the accommodating recess 33 and the thrust receiving ball 44. The thrust receiving plate 45 is made of, for example, a steel material obtained by heat-treating (quenching) a metal in advance. The thrust receiving plate 45 is preferably press-fitted and fixed to the receiving recess 33 by an adhesive or the like. The thrust receiving ball 44 is magnetically attracted to the inner peripheral surface 33a of the housing recess 33 and the thrust receiving plate 45 by the magnetic force of the magnet portion 44a that the thrust receiving ball 44 has.

  Even with such a configuration, an effect substantially similar to the effect (1) of the above embodiment can be obtained. In the example shown in FIG. 8, even when the worm shaft 22 is formed of a non-magnetic material such as resin, the thrust receiving plate 45 fixed to the receiving recess 33 is made of a magnetic material, so that the ball 44 is a thrust receiving plate. It is magnetically attracted by 45 and is held in the housing recess 33.

  In the example shown in FIG. 8, only the central core portion (magnet portion 44a) of the thrust receiving ball 44 is magnetized. However, for example, the entire thrust receiving ball 44 is formed of a magnetic material. The entire thrust receiving ball 44 may be magnetized.

  -Instead of the plate-shaped magnet member 31 of the said embodiment, you may provide the metal ball | bowl 51 as shown, for example in FIG. The metal ball 51 has the same material and the same shape (same diameter) as the thrust receiving ball 32, and is interposed between the bottom surface 33 b of the receiving recess 33 and the thrust receiving ball 32 in the axial direction. The metal ball 51 is magnetized, and the thrust receiving ball 32 is held in the housing recess 33 by the magnetic force of the metal ball 51.

  Even with such a configuration, the same effect as the effect (1) of the above embodiment can be obtained. Further, according to this configuration, when the thrust receiving ball 32 contacts the metal ball 51 and receives a force, the metal ball 51 rotates and friction with the thrust receiving ball 32 is reduced. Wear of the member (metal ball 51) can be further suppressed.

  In the example shown in FIG. 9, the bottom surface 33 b of the housing recess 33 has a tapered shape whose diameter increases toward the opening side in the axial direction (the base end surface 22 e side of the worm shaft 22). It is held at the center of the diameter of the housing recess 33.

  In the example shown in FIG. 9, if the thrust receiving ball 32 is magnetized in the same manner as the metal ball 51, the thrust receiving ball 32 and the metal ball 51 are the same member. As a result, the types of motor parts are reduced, and parts management is facilitated.

  In the example shown in FIGS. 10 and 11, three metal balls 52 are interposed between the bottom surface 33 b of the housing recess 33 and the thrust receiving ball 32 instead of the plate-like magnet member 31 of the above embodiment. Yes. Each metal ball 52 is smaller in diameter than the thrust receiving ball 32 and has the same shape as each other, and is formed of the same material as the thrust receiving ball 32. Each metal ball 52 is disposed so as to surround the axis L of the worm shaft 22, and the thrust receiving ball 32 is disposed so as to abut on each metal ball 52.

  Even with such a configuration, when the thrust receiving ball 32 contacts the metal ball 52 and receives a force, the metal ball 52 rotates and friction with the thrust receiving ball 32 is reduced. Wear of the (metal sphere 52) can be further suppressed. Further, in the example shown in FIGS. 10 and 11, the thrust receiving ball 32 is supported by each metal ball 52, and the position of the thrust receiving ball 32 is such that the center of the thrust receiving ball 32 coincides with the axis L of the worm shaft 22. Can be held.

  In the above embodiment, the worm shaft 22 is formed of a magnetic material, and the magnet member 31 is magnetically attracted to the housing recess 33 of the worm shaft 22. You may form with the member which is hard to pass. In this case, since the magnet member 31 cannot be magnetically attracted to the housing recess 33 of the worm shaft 22, the thrust receiving ball 32 is magnetically attracted to the magnet member 31, but both the magnet member 31 and the thrust receiving ball 32 are housed in the housing recess. There is a risk of falling off 33. Therefore, the thrust receiving ball 32 magnetically attracted to the magnet member 31 can be held in the housing recess 33 by press-fitting and fixing the magnet member 31 to the housing recess 33 with an adhesive or the like. It becomes.

  In the above embodiment, the thrust receiving ball 32 is partially protruded from the receiving recess 33 and the protruding portion is used as the thrust receiving portion for the armature shaft 15. However, the thrust receiving ball 32 as a whole may be stored in the receiving recess 33. Good. However, in the configuration in which the entire thrust receiving ball 32 is accommodated in the accommodating recess 33, the distal end portion 15 b of the armature shaft 15 that contacts the thrust receiving ball 32 enters the accommodating recess 33. For example, in the radial direction of the worm shaft 22. There is a possibility that the worm shaft 22 may interfere with the armature shaft 15 when the shaft is displaced. In that respect, if the thrust receiving ball 32 is partially protruded from the housing recess 33 as in the above embodiment, the worm shaft 22 can be configured not to interfere with the armature shaft 15 even when the shaft is displaced. .

  In the above embodiment, the housing recess 33 for housing the thrust receiving ball 32 and the magnet member 31 is provided in the base end portion 22b (base end surface 22e) of the worm shaft 22. However, the present invention is not limited to this. You may provide in the front end surface (shaft end surface of the front-end | tip part 15b) of the axis | shaft 15. FIG.

  In the above embodiment, the present invention is applied to the thrust receiving structure (thrust receiving ball 32) between the armature shaft 15 and the worm shaft 22. However, the present invention is not particularly limited to this. You may apply to the thrust receiving part 25. FIG. In other words, the speed reducing portion side thrust receiving portion 25 may be configured such that the ball 25b can be magnetically held with respect to the concave portion 22d at the tip of the worm shaft 22.

  DESCRIPTION OF SYMBOLS 11 ... Motor body, 12 ... Rotation transmission part, 13 ... Deceleration part, 15 ... Armature shaft (2nd rotation shaft, drive shaft), 22 ... Worm shaft (rotation shaft, driven shaft), 31, 43 ... Magnet member, 32, 44 ... Thrust receiving balls, 33 ... Housing recesses, 41 ... Sliding receiving plates, 51, 52 ... Metal balls.

Claims (10)

A thrust receiving structure comprising a rotating shaft and a thrust receiving ball made of a magnetic material rotatably accommodated in a receiving recess provided at one end of the rotating shaft and into which a lubricant is injected ,
The rotating shaft is provided with a magnet member for holding the thrust receiving ball in the receiving recess by magnetism,
The thrust receiving ball is held in the receiving recess by the magnetism of the magnet member ,
The magnet member is interposed between the bottom surface of the housing recess and the thrust receiving ball, and a clearance is set between the outer surface of the magnet member and the inner wall surface of the housing recess. Characteristic thrust receiving structure. The thrust receiving structure according to claim 1 ,
The thrust receiving structure, wherein the magnet member is formed by magnetizing a steel material harder than the material of the rotating shaft. The thrust receiving structure according to claim 1 ,
A thrust receiving structure, wherein a sliding receiving plate made of a magnetic material is interposed between the magnet member and the thrust receiving ball. The thrust receiving structure according to claim 3,
A thrust receiving structure, wherein a clearance is set between an outer surface of the sliding receiving plate and an inner wall surface of the receiving recess. In the thrust receiving structure according to any one of claims 1 to 4 ,
The thrust receiving structure according to claim 1, wherein an inner peripheral surface of the housing recess has a tapered shape that expands toward the opening side. The thrust receiving structure according to any one of claims 1 to 5 ,
A thrust receiving structure, wherein at least a part of the thrust receiving ball is magnetized. In the thrust receiving structure according to any one of claims 1 to 6 ,
The thrust receiving ball is configured to contact a shaft end portion of a second rotating shaft that is rotationally connected to the rotating shaft and to receive a thrust load from the second rotating shaft. Thrust receiving structure. The thrust receiving structure according to claim 7,
The thrust receiving structure, wherein the thrust receiving ball is partially protruded from the receiving recess, and the protruding portion of the thrust receiving ball is configured to abut the shaft end of the second rotating shaft. . A motor comprising the thrust receiving structure according to any one of claims 1 to 8 . The motor according to claim 9 , wherein
A motor body having a drive shaft;
A reduction portion having a driven shaft that is coaxially disposed with the drive shaft and is rotatable integrally with the drive shaft;
The drive shaft is a second rotary shaft that is rotationally connected to the rotary shaft, or the rotary shaft,
The driven shaft is the rotating shaft or the second rotating shaft;
A motor comprising the thrust receiving structure between the drive shaft and the driven shaft.