JP2021145546A - Motor and manufacturing method of motor - Google Patents

Abstract

To provide a technique which can contribute to improve productivity in regards to a motor in which a pinion shaft is assembled to a motor shaft.SOLUTION: A motor 12 comprises: a motor shaft 32 having a concave part 32b in a load end part; a pinion shaft 34 pressed into the concave part 32b; a load side bearing 36 that supports the motor shaft 32; and a non-load side bearing 38. The motor further comprises a load transmission structure 40 which make a thrust load Fa operated to the motor shaft 32 toward a non-load side possible to transmit for the load side bearing 36 and a load reception member 64 other than the non-load side bearing 38.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method of assembling a motor and a pinion shaft.

A pinion shaft may be attached to the motor shaft in order to transmit the rotational power to the speed reducer or the driven device. As an example of this, Patent Document 1 discloses a motor in which a recess is provided in the motor shaft and the pinion shaft is pushed into the recess by shrink fitting.

Japanese Unexamined Patent Publication No. 2016-63599

When shrink fitting is used for assembling the pinion shaft as in the motor of Patent Document 1, it is necessary to heat the concave portion of the motor shaft. Along with this, the time required for assembling the pinion shaft increases more, so there is room for improvement from the viewpoint of productivity.

One aspect of the present invention has been made in view of these circumstances, one of which is to provide a technique for improving productivity of a motor in which a pinion shaft is assembled to a motor shaft.

One aspect of the present invention relates to a motor. This motor is a motor including a motor shaft having a recess at the end on the load side, a pinion shaft pushed into the recess, and a load-side bearing and a non-load-side bearing that support the motor shaft. Provided is a load transmission structure for enabling a thrust load acting on the motor shaft toward the counterload side to be transmitted to a load receiving member other than the load side bearing and the counterload side bearing.

Another aspect of the invention relates to a motor. This motor is a motor including a motor shaft having a recess at the end on the load side and a pinion shaft pushed into the recess, for inserting a bolt into the pinion shaft from the load side. An insertion hole is formed, and a tap hole for screwing the bolt is formed at the bottom of the recess.

Another aspect of the present invention relates to a method of assembling a pinion shaft. This method is a method for assembling a pinion shaft to a motor shaft of a motor. The motor shaft has a recess at a load side end, and the motor has a load side bearing and a counter that support the motor shaft. A load-side bearing and a load-transmitting structure for enabling a thrust load acting on the motor shaft toward the counter-load side to be transmitted to a load receiving member other than the load-side bearing and the counter-load-side bearing. The pinion shaft is press-fitted into the recess in a state where the thrust load can be transmitted from the motor shaft to the load receiving member by using the load transmission structure.

Another aspect of the present invention relates to a method of assembling a pinion shaft. This method is a method for assembling a pinion shaft to a motor shaft of a motor, in which the motor shaft has a recess at an end on the load side, and a bolt is inserted into the pinion shaft from the load side. An insertion hole is formed, a tap hole is formed at the bottom of the recess, and a bolt inserted into the insertion hole is screwed into the tap hole to apply a pressure input from the bolt to the pinion shaft. The pinion shaft is press-fitted into the recess.

According to the present invention, it is possible to provide a technique useful for improving productivity with respect to a motor in which a pinion shaft is assembled to a motor shaft.

It is sectional drawing which shows the gear motor which uses the motor of 1st Embodiment. It is a figure which shows the assembly process of the pinion shaft of 1st Embodiment. It is a figure which shows the assembly process of the pinion shaft using the motor of 2nd Embodiment. It is a figure which shows the assembly process of the pinion shaft using the motor of 3rd Embodiment. It is a figure which shows the assembly process of the pinion shaft using the motor of 4th Embodiment. It is a figure which shows the assembly process of the pinion shaft using the motor of 5th Embodiment. It is an enlarged view around the pinion axis of FIG. FIG. 8A is a diagram showing an intermediate state of the pinion shaft assembling process of the fifth embodiment, and FIG. 8B is another diagram showing an intermediate state of the pinion shaft assembling process of the fifth embodiment. It is a figure.

Hereinafter, in the embodiments and modifications, the same components will be designated by the same reference numerals, and duplicate description will be omitted. Further, in each drawing, for convenience of explanation, some of the constituent elements are appropriately omitted, and the dimensions of the constituent elements are appropriately enlarged or reduced.

(First Embodiment)
First, the background that led to the idea of the motor of the first embodiment will be described. For a motor in which the pinion shaft is assembled to the motor shaft, it is conceivable to use press fitting for assembling the pinion shaft in order to improve productivity. When the pinion shaft is press-fitted into the motor shaft, a thrust load from the pinion shaft toward the opposite load side acts on the motor shaft. This thrust load is usually received by a counterload side bearing that supports the motor shaft. Therefore, if the thrust load acting on the motor shaft increases, there is a concern that the load on the bearing on the non-load side will be increased. In particular, when press-fitting is used for assembling the pinion shaft, the thrust load acting on the motor shaft increases as compared with the case where shrink fitting is used, so that the load on the bearing on the non-load side is more concerned.

As a countermeasure against this, the motor of the present embodiment is provided with a load transmission structure for enabling the thrust load acting on the motor shaft toward the counterload side to be transmitted to the load receiving member. As a result, the pinion shaft can be press-fitted into the recess of the motor shaft while the thrust load can be transmitted from the motor shaft to the load receiving member using the load transmission structure, and the load on the counter-load side bearing at the time of press-fitting can be applied. It can be suppressed. Therefore, according to the motor of the present embodiment, the pinion shaft can be press-fitted into the recess of the motor shaft while suppressing the load on the bearing on the non-load side, which can be useful for improving the productivity of the motor. Hereinafter, the details of the motor of the first embodiment will be described.

FIG. 1 is a cross-sectional view showing a gear motor 10 in which the motor 12 of the first embodiment is used. The gear motor 10 includes a motor 12 and a speed reducer 14, and these are integrated. In the present specification, the axial direction, the circumferential direction, and the radial direction of the motor shaft 32 of the motor 12 are also simply referred to as "axial direction", "circumferential direction", and "diameter direction". Of the axial directions of the motor shaft 32, the side closer to the driven device on the power transmission path passing through the motor shaft 32 is referred to as the load side, and the side opposite to the load side is referred to as the counterload side. The speed reducer 14 will be described first.

The speed reducer 14 includes a speed reducer casing 16, an output member 18, and a speed reduction mechanism 20. The speed reducer casing 16 has a cylindrical casing main body 22 in which the speed reduction mechanism 20 is housed, and a counter load side wall portion 24 arranged on the counter load side of the speed reduction mechanism 20. The casing main body 22 of the present embodiment has a first main body member 22a arranged on the counterload side and a second main body member 22b arranged on the load side.

The output member 18 is for outputting the rotational power of the motor shaft 32 to the driven device. The output member 18 is housed inside the casing main body 22, and is rotatably supported by the casing main body 22 via a bearing (not shown).

The speed reduction mechanism 20 can reduce the rotational power of the motor shaft 32 and transmit it to the output member 18. The deceleration mechanism 20 of the present embodiment is a distribution type eccentric swing deceleration mechanism. Since this type of deceleration mechanism 20 is known, the description thereof will be briefly described here.

The speed reduction mechanism 20 has a plurality of input gears 26 arranged around the pinion shaft 34, which will be described later. In this figure, only one input gear 26 is shown. The input gear 26 meshes with the pinion portion 34b of the pinion shaft 34. The input gear 26 is supported by a crankshaft 28 inserted into the central portion thereof, and is provided so as to be rotatable integrally with the crankshaft 28. When the input gear 26 is rotated by the rotation of the pinion shaft 34, the rotation of the pinion shaft 34 is decelerated and transmitted from the speed reduction mechanism 20 to the output member 18.

The explanation of the motor 12 will be given. The motor 12 of this embodiment is a servo motor. The motor 12 mainly includes a motor casing 30, a motor shaft 32, a pinion shaft 34, a load side bearing 36, a counterload side bearing 38, and a load transmission structure 40.

The motor casing 30 includes a motor frame 42, a load side cover 44, a first counterload side cover 46, and a second counterload side cover 48.

The motor frame 42 has a cylindrical shape, and the stator 50 and the rotor 52 are housed inside the motor frame 42. The stator 50 can generate a rotating magnetic field for rotating the rotor 52 and is fixed to the motor frame 42. The rotor 52 is rotatable by magnetic interaction with the rotating magnetic field generated by the stator 50. The motor shaft 32 is provided so as to be rotatable integrally with the rotor 52.

The load-side cover 44 covers the load-side opening of the motor frame 42 and is fixed to the motor frame 42 by bolts. The load-side cover 44 of the present embodiment also serves as the anti-load side wall portion 24 of the speed reducer casing 16. However, the load side cover 44 may be provided separately from the anti-load side wall portion 24 without also serving as the anti-load side wall portion 24 of the speed reducer casing 16. The load-side cover 44 separates the internal space 30a of the motor casing 30 from another space 54 provided on the load side of the internal space 30a. The other space 54 in this embodiment is the internal space of the speed reducer casing 16.

The load-side cover 44 is formed with a first through-hole 44a that penetrates the load-side cover 44 in the axial direction and through which the motor shaft 32 is inserted. An oil seal 56 is interposed between the motor shaft 32 and the first through hole 44a. The oil seal 56 regulates the leakage of the lubricating oil sealed in the speed reducer casing 16. The oil seal 56 is provided on the opposite side of the opening end edge 44b on the load side of the first through hole 44a.

In the load side cover 44, the first fitting portion 44c is formed in the counterload side portion of the first through hole 44a. A load-side bearing 36 is fitted into the first fitting portion 44c by gap fitting, and the load-side cover 44 supports the load-side bearing 36 in the first fitting portion 44c. The load-side bearing 36 may be fitted into the first fitting portion 44c by tightening.

The first counterload side cover 46 covers the counterload side opening of the motor frame 42 and is fixed to the motor frame 42 by bolts. The first counterload side cover 46 separates the internal space 30a of the motor casing 30 from the other spaces 48a and 58 provided on the counterload side of the internal space 30a. The other spaces 48a and 58 in the present embodiment are the inner cover inner space 48a of the second counterload side cover 48 and the outer outer space 58 of the motor casing 30.

The first counterload side cover 46 is formed with a second through hole 46a through which the first counterload side cover 46 is axially penetrated and the motor shaft 32 is inserted. In the first counterload side cover 46, a second fitting portion 46b is formed in the load side portion of the second through hole 46a. A counterload side bearing 38 is fitted into the second fitting portion 46b by gap fitting, and the first counterload side cover 46 supports the counterload side bearing 38 in the second fitting portion 46b. The counterload side bearing 38 may be fitted into the second fitting portion 46b by tightening.

The second counterload side cover 48 is arranged on the counterload side with respect to the first counterload side cover 46. The second counterload side cover 48 has a covering portion 48a having a bottomed cylindrical shape, and a flange portion 48b protruding radially outward from the open end edge of the covering portion 48a. The flange portion 48b is abutted against the anti-load side wall surface of the first anti-load side cover 46, and is detachably attached to the first anti-load side cover 46 by using a mounting bolt 60.

The load-side end 32a of the motor shaft 32 projects toward the load side from the load-side cover 44. The motor shaft 32 has a recess 32b formed in the load side end portion 32a. The recess 32b is formed so as to be recessed from the load side end surface of the motor shaft 32 to the opposite load side.

The counterload side end portion 32c of the motor shaft 32 projects to the counterload side from the first counterload side cover 46. The counterload side end portion 32c of the motor shaft 32 is covered from the counterload side and the radial outside by the cover portion 48a of the second counterload side cover 48.

A rotation angle detecting device 62 is arranged around the counterload side end portion 32c of the motor shaft 32. The rotation angle detection device 62 is for detecting the rotation angle of the motor shaft 32, and is, for example, a rotary encoder. The detection signal of the rotation angle detection device 62 is output to an external control device (not shown) and used for controlling the motor 12 by the external control device. The rotation angle detection device 62 includes a housing 62a that houses detection elements such as a light emitting element and a light receiving element. A part of the non-load side end 32c of the motor shaft 32 projects from the housing 62a to the non-load side. The rotation angle detection device 62 is covered from the counterload side or the radial outside by the covering portion 48a of the second counterload side cover 48.

A fan for cooling the motor casing 30 is not mounted on the counterload side end portion 32c of the motor shaft 32. This fan is provided so as to be rotatable integrally with the motor shaft 32, and the rotation of the fan generates an air flow that cools the motor casing 30.

The pinion shaft 34 is provided coaxially with the motor shaft 32. The pinion shaft 34 has a shaft portion 34a pushed into the recess 32b of the motor shaft 32, and a pinion portion 34b provided on the load side of the shaft portion 34a. The shaft portion 34a is fitted into the recess 32b of the motor shaft 32 by tightening, and can rotate integrally with the motor shaft 32. A plurality of tooth portions that mesh with the input gear 26 are formed on the outer peripheral surface of the pinion portion 34b. The rotational power of the motor shaft 32 is transmitted to the input gear 26 via the pinion shaft 34 by the meshing of the input gear 26 and the pinion portion 34b.

The load-side bearing 36 rotatably supports the load-side portion on the load side of the rotor 52 of the motor shaft 32. The load side bearing 36 is, for example, a rolling bearing or the like. The inner ring of the load-side bearing 36 is fixed to the load-side portion of the motor shaft 32 by tightening and fitting.

The counterload side bearing 38 rotatably supports the counterload side portion on the counterload side of the rotor 52 of the motor shaft 32. The counterload side bearing 38 is, for example, a rolling bearing or the like. The inner ring of the load-side bearing 36 is fixed to the non-load-side portion of the motor shaft 32 by tightening and fitting.

FIG. 2 is a diagram showing an assembling process of the pinion shaft 34. The load transmission structure 40 is for enabling the thrust load Fa acting on the motor shaft 32 to be transmitted to the load receiving member 64 other than the load side bearing 36 and the non-load side bearing 38. This thrust load Fa acts on the motor shaft 32 toward the opposite load side when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32.

The load transmission structure 40 of the present embodiment is the counterload side end surface 32d of the motor shaft 32. The counterload side end surface 32d of the motor shaft 32 is exposed to the external space 58 on the counterload side of the first counterload side cover 46 when the second counterload side cover 48 is not present. Here, "when there is no second counterload side cover 48" means that in the present embodiment, the second counterload side cover 48 is in the stage before being attached to the first counterload side cover 46.

The load receiving member 64 is arranged in the external space 58 on the counterload side of the first counterload side cover 46. The load receiving member 64 serves as a transmission destination of the thrust load Fa acting on the motor shaft 32. The load receiving member 64 is provided with a receiving surface 64a for receiving the thrust load Fa of the motor shaft 32. The receiving surface 64a of the present embodiment is a flat surface. The counter-load side end surface 32d of the motor shaft 32 is directly in contact with the receiving surface 64a of the load receiving member 64. As a result, the thrust load Fa of the motor shaft 32 can be transmitted from the motor shaft 32 to the load receiving member 64.

A method of assembling the pinion shaft 34 using the above motor 12 will be described. First, the components of the motor 12 are assembled to the motor casing 30, and the semi-finished product 66 to which the pinion shaft 34 is not assembled to the motor shaft 32 is prepared. The components to be assembled here include the motor shaft 32, the load side bearing 36, the counterload side bearing 38, the stator 50, the rotor 52, the rotation angle detection device 62, and the like, and the second counterload side cover 48. Is not included.

The semi-finished product 66 of the present embodiment is assembled with the first main body member 22a of the speed reducer casing 16, and is not assembled with other components (reduction mechanism 20 and the like) of the speed reducer 14. As a result, a space in which the press die can be arranged is secured inside the first main body member 22a.

Subsequently, the load transmission structure 40 is used to bring the thrust load Fa of the motor shaft 32 into a state in which the thrust load Fa can be transmitted from the motor shaft 32 to the load receiving member 64 (hereinafter, referred to as a load transmission possible state). In the present embodiment, the semi-finished product 66 of the motor 12 is brought into a load transmitting state by bringing the counterload side end surface 32d of the motor shaft 32, which is the load transmitting structure 40, into contact with the receiving surface 64a of the load receiving member 64. ..

Subsequently, while the semi-finished product 66 of the motor 12 is in a load-transmissible state, the shaft portion 34a of the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32 toward the counterload side. In this press-fitting step, a press-fitting force is applied to the pinion shaft 34 using a press die or the like. This press-fitting step is performed in a state where the semi-finished product 66 of the motor 12 and the load receiving member 64 are fixed by a jig or the like. This press-fitting step is performed in a room temperature environment without heating the motor shaft 32 and the pinion shaft 34. The pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32 until it hits the bottom surface of the recess 32b. The press-fitting of the pinion shaft 34 may be stopped before it hits the bottom surface of the recess 32b of the motor shaft 32. After the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the second counterload side cover 48 is attached to the first counterload side cover 46.

As a result, when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the thrust load Fa acting on the motor shaft 32 is transmitted to the load receiving member 64, and the load on the counterload side bearing 38 can be suppressed. In the present embodiment, the thrust load Fa is transmitted from the counterload side end surface 32d of the motor shaft 32 to the load receiving member 64. That is, the thrust load Fa is transmitted from the load transmission structure 40 of the motor shaft 32 to the load receiving member 64.

Further, in the present embodiment, since the load transmission structure 40 is the counterload side end surface 32d of the motor shaft 32, it is not necessary to attach / detach other members to / from the motor shaft 32 when assembling the pinion shaft 34. Further, since the motor 12 includes a second counterload side cover 48 that covers the counterload side end surface 32d of the motor shaft 32, the motor shaft 32 can be protected from contact with an external object and safety can be ensured.

An example has been described in which the counterload side end surface 32d of the motor shaft 32, which is the load transmission structure 40, protrudes to the counterload side from the first counterload side cover 46. In addition to this, when the counterload side end surface 32d of the motor shaft 32 is exposed to the external space 58, the counterload side end surface 32d does not have to protrude from the first counterload side cover 46 to the counterload side. In this case, for example, the load receiving member 64 is provided with a protrusion that protrudes toward the load side and can be inserted into the second through hole 46a of the first counterload side cover 46, and the receiving surface 64a is provided at the tip of the protrusion. It may be provided. This also makes it possible to bring the load transferable state described above.

(Second Embodiment)
FIG. 3 is a diagram showing an assembling process of the pinion shaft 34 using the motor 12 of the second embodiment. The motor 12 of the second embodiment is mainly different from the first embodiment in the load transmission structure 40. The load transmission structure 40 of the second embodiment is a female screw hole 32e formed in the counterload side end surface 32d of the motor shaft 32. The female screw hole 32e functions as a mounting portion for mounting the screw member 68, which will be described later, in a detachable manner.

A screw member 68 is attached to the female screw hole 32e of the motor shaft 32. The screw member 68 functions as a load transmission member 70 for transmitting the thrust load of the motor shaft 32 from the motor shaft 32 to the load receiving member 64. The screw member 68 also functions as a protruding member that projects from the counterload side end surface 32d of the motor shaft 32 to the counterload side. The screw member 68 is attached to the motor shaft 32 only in the assembling step of the pinion shaft 34, and is removed from the motor shaft 32 after the motor 12 is assembled.

The screw member 68 has a screw shaft portion 68a on which a male screw portion is formed, and a head portion 68b provided on the proximal end side of the screw shaft portion 68a. The screw member 68 is attached by screwing the screw shaft portion 68a into the female screw hole 32e of the motor shaft 32. A contact surface 70a for abutting the receiving surface 64a of the load receiving member 64 is formed on the head 68b of the screw member 68. The contact surface 70a of the present embodiment is a flat surface. When the second counterload side cover 48 is not provided, the screw member 68 is exposed to the external space 58 on the counterload side of the first counterload side cover 46.

A method of assembling the pinion shaft 34 using the above motor 12 will be described. First, as in the first embodiment, a semi-finished product 66 in which the pinion shaft 34 is not assembled to the motor shaft 32 is prepared.

Subsequently, the screw member 68 is attached to the female screw hole 32e of the motor shaft 32 that becomes the load transmission structure 40, and the contact surface 70a of the screw member 68 is brought into contact with the receiving surface 64a of the load receiving member 64. As a result, the thrust load Fa of the motor shaft 32 can be transmitted from the motor shaft 32 to the load receiving member 64 by using the female screw hole 32e which is the load transmission structure 40.

Subsequently, while the semi-finished product 66 of the motor 12 is in a load-transmissible state, the shaft portion 34a of the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32 toward the counterload side. After that, the screw member 68 is removed from the female screw hole 32e of the motor shaft 32, and the second counterload side cover 48 is attached to the first counterload side cover 46.

As a result, when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the thrust load Fa acting on the motor shaft 32 is transmitted to the load receiving member 64, and the load on the counterload side bearing 38 can be suppressed. In the present embodiment, the thrust load Fa is transmitted from the female screw hole 32e of the motor shaft 32 to the load receiving member 64 via the screw member 68. That is, the thrust load Fa is transmitted from the load transmission structure 40 of the motor shaft 32 to the load receiving member 64 via the load transmission member 70.

Further, in the present embodiment, by mounting the screw member 68 on the anti-load side end surface 32d of the motor shaft 32, the load receiving member 64 is hit at a position away from the anti-load side end surface 32d of the motor shaft 32 on the anti-load side. A contact surface 70a for contact can be arranged. Therefore, by adjusting the axial dimension of the screw member 68 regardless of the protruding dimension of the motor shaft 32 from the first non-load side cover 46, it becomes easy to bring the semi-finished product 66 of the motor 12 into a load transferable state. Therefore, in order to make the semi-finished product 66 of the motor 12 capable of transmitting a load, a design that reduces the protruding dimension of the motor shaft 32 and a design that does not project the motor shaft 32 from the first counterload side cover 46 are permitted. ..

In this embodiment, an example will be described in which the protruding member protruding from the counterload side end surface 32d of the motor shaft 32 to the counterload side is the screw member 68, and the mounting portion on which the protruding member is mounted is the female screw hole 32e. bottom. The combination of the protruding member and the mounting portion is not limited to the combination of the screw member 68 and the female screw hole 32e. For example, the mounting portion may be a recess provided on the counter-load side end surface 32d of the motor shaft 32, and the projecting member may be a columnar body that is partially pushed into the recess and extends coaxially with the motor shaft 32. Further, when the load transmission structure 40 serves as a mounting portion as in the present embodiment, a fan may be mounted on the counter-load side end portion 32c of the motor shaft 32.

(Third Embodiment)
FIG. 4 is a diagram showing an assembling step of the pinion shaft 34 using the motor 12 of the third embodiment. An example has been described in which the load receiving member 64 of the first embodiment and the second embodiment is a member different from the motor 12. The load receiving member 64 of this embodiment is a load side cover 44 of the motor 12. A receiving surface 64a for receiving the thrust load Fa of the motor shaft 32 is provided on the load side wall surface of the load side cover 44. The receiving surface 64a of the present embodiment is provided at the peripheral edge of the opening on the load side of the first through hole 44a. The receiving surface 64a of the present embodiment is a flat surface and has an annular shape concentric with the motor shaft 32.

In the second embodiment, the female screw hole 32e (mounting portion) formed on the counter-load side end surface 32d of the motor shaft 32 is the load transmission structure 40, and the screw member 68 mounted in the female screw hole 32e is the load transmission member. An example of 70 has been described.

The load transmission structure 40 of the present embodiment is a through hole 32f formed in the load side portion of the motor shaft 32. The through hole 32f functions as a holding portion for holding the contact member 72, which will be described later, in a detachable manner. The through hole 32f is provided in the vicinity of the receiving surface 64a of the load side cover 44. More specifically, the through hole 32f is provided at a position that overlaps or substantially overlaps the receiving surface 64a of the load side cover 44 in the axial direction. Further, the through hole 32f is provided on the side opposite to the load side from the recess 32b of the motor shaft 32. The through hole 32f extends linearly along a direction orthogonal to the axial direction of the motor shaft 32.

The load transmission member 70 of the present embodiment is a contact member 72 that is inserted into the through hole 32f of the motor shaft 32 and is held in the through hole 32f. As a result, the contact member 72 is held in an axial position with respect to the motor shaft 32. The abutting member 72 is held by the motor shaft 32 only in the assembling step of the pinion shaft 34, and is removed from the motor shaft 32 after the motor 12 is assembled.

The contact member 72 of the present embodiment is a long body, and is inserted and removed from the through hole 32f of the motor shaft 32 in the longitudinal direction (left-right direction in the drawing) of the contact member 72. The abutting member 72 and the through hole 32f have a cross-sectional shape that fits each other. In the present embodiment, the contact member 72 has a prismatic cross-sectional shape, and the through hole 32f has a square hole-shaped cross section that fits with the contact member 72.

The contact member 72 has a contact surface 70a that contacts the receiving surface 64a of the load side cover 44. The contact surface 70a of the present embodiment is a flat surface facing the counterload side, and is provided at both ends of the contact member 72 in the longitudinal direction. The contact surface 70a of the contact member 72 contacts the receiving surface 64a of the load side cover 44 in a surface contact state. The load-side inner wall surface of the through hole 32f of the motor shaft 32 also comes into contact with the load-side outer wall surface of the contact member 72 in a state of surface contact.

A method of assembling the pinion shaft 34 using the above motor 12 will be described. First, as in the first embodiment, a semi-finished product 66 in which the pinion shaft 34 is not assembled to the motor shaft 32 is prepared. At this time, unlike the first embodiment and the second embodiment, the second counterload side cover 48 may be attached to the semi-finished product 66 of the motor 12.

Subsequently, the contact member 72 is inserted into the through hole 32f of the motor shaft 32 which is the load transmission structure 40, the contact member 72 is held in the through hole 32f of the motor shaft 32, and the contact surface of the contact member 72 is held. The 70a is brought into contact with the receiving surface 64a of the load side cover 44. As a result, the load transmission possible state is such that the thrust load Fa of the motor shaft 32 can be transmitted from the motor shaft 32 to the load side cover 44 by using the load transmission structure 40.

Subsequently, while the semi-finished product 66 of the motor 12 is in a load-transmissible state, the shaft portion 34a of the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32 toward the counterload side. After that, the contact member 72 is pulled out from the through hole 32f of the motor shaft 32.

As a result, when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the thrust load Fa acting on the motor shaft 32 is transmitted to the load side cover 44, and the load on the counterload side bearing 38 can be suppressed. In the present embodiment, the thrust load Fa is transmitted from the through hole 32f of the motor shaft 32 to the load side cover 44 via the contact member 72. That is, the thrust load Fa is transmitted from the load transmission structure 40 of the motor shaft 32 to the load side cover 44 via the load transmission member 70.

(Fourth Embodiment)
FIG. 5 is a diagram showing an assembling step of the pinion shaft 34 using the motor 12 of the fourth embodiment. In the third embodiment, an example in which the through hole 32f formed in the load side portion of the motor shaft 32 is the load transmission structure 40 has been described.

In the present embodiment, the groove portion 32g formed on the load side portion of the motor shaft 32 serves as the load transmission structure 40. The groove portion 32g is formed along the circumferential direction on the outer peripheral surface of the load side portion of the motor shaft 32. The groove portion 32g functions as a holding portion for holding the contact member 72, which will be described later, in a detachable manner.

The contact member 72 of the present embodiment is between the retaining ring 72a held in the groove 32g by being fitted into the groove 32g of the load transmission structure 40, and the receiving surface 64a and the retaining ring 72a of the load side cover 44. It has a ring member 72b sandwiched between the two. The retaining ring 72a has an annular shape with a part cut out, and the diameter can be expanded in the radial direction. A load-side portion of the motor shaft 32 is inserted inside the ring member 72b. The contact member 72 is formed in the groove portion 32g of the motor shaft 32 by fitting the retaining ring 72a into the groove portion 32g of the motor shaft 32 and sandwiching the ring member 72b between the load side cover 44 and the retaining ring 72a. Retained. At this time, the contact member 72 is held in an axial position with respect to the motor shaft 32.

A method of assembling the pinion shaft 34 using the above motor 12 will be described. First, as in the third embodiment, a semi-finished product 66 in which the pinion shaft 34 is not assembled to the motor shaft 32 is prepared.

Subsequently, the load side portion of the motor shaft 32 is inserted into the ring member 72b of the contact member 72, and the ring member 72b is moved to the opposite load side until it comes into contact with the receiving surface 64a of the load side cover 44. .. After that, the retaining ring 72a of the contact member 72 is fitted into the groove portion 32g of the motor shaft 32 to hold the retaining ring 72a and the ring member 72b with respect to the motor shaft 32, that is, the positions of the contact member 72 in the axial direction. As a result, the thrust load Fa of the motor shaft 32 can be transmitted from the motor shaft 32 to the load side cover 44 by using the groove portion 32 g which is the load transmission structure 40.

Subsequently, while the semi-finished product 66 of the motor 12 is in a load-transmissible state, the shaft portion 34a of the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32 toward the counterload side. After that, the retaining ring 72a of the contact member 72 is enlarged in diameter and removed from the groove portion 32g of the motor shaft 32, and then the ring member 72b of the contact member 72 is also removed from the motor shaft 32.

As a result, when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the thrust load Fa acting on the motor shaft 32 is transmitted to the load side cover 44, and the load on the counterload side bearing 38 can be suppressed. In the present embodiment, the thrust load is transmitted from the groove 32g of the motor shaft 32 to the load side cover 44 via the contact member 72. That is, the thrust load Fa is transmitted from the load transmission structure 40 of the motor shaft 32 to the load side cover 44 via the load transmission member 70.

In the third embodiment, the holding portion for holding the contact member 72 that abuts on the load side cover 44 is the through hole 32f, and in the fourth embodiment, the holding portion is the groove portion 32g. This holding portion is not limited to these. Further, in the contact member 72 of the fourth embodiment, the first member fitted into the groove portion 32g serving as the holding portion is a retaining ring 72a, which is sandwiched between the receiving surface 64a of the load side cover 44 and the retaining ring 72a. An example in which the second member is the ring member 72b has been described. The combination of the first member and the second member is not limited to the retaining ring 72a and the ring member 72b. For example, the first member may be a long body inserted into a through hole formed as a holding portion in the motor shaft 32. Further, a male screw portion may be formed on the motor shaft 32 as a holding portion, and a nut body as a contact member 72 may be attached to the male screw portion.

(Fifth Embodiment)
FIG. 6 is a diagram showing an assembling step of the pinion shaft 34 using the motor 12 of the fifth embodiment. In the above-described embodiment, an example in which the load transmission structure 40 is provided in the motor 12 has been described in order to suppress the load on the counterload side bearing 38 when the pinion shaft 34 is press-fitted. In the present embodiment, for the same purpose, instead of providing the load transmission structure 40 in the motor 12, the following configuration is adopted.

FIG. 7 is an enlarged view around the pinion axis 34 of FIG. The pinion shaft 34 is formed with an insertion hole 34c for inserting the press-fit bolt 74 from the load side. The press-fitting bolt 74 is used for press-fitting the pinion shaft 34 into the recess 32b of the motor shaft 32, as will be described later. The insertion hole 34c is formed along the axial direction of the motor shaft 32. The insertion hole 34c penetrates the pinion shaft 34 in the axial direction and opens toward both sides in the axial direction. The insertion hole 34c is a drilled hole that allows the press-fitting bolt 74 to be inserted and removed in the axial direction without rotation. A tap hole 32h for screwing the press-fitting bolt 74 is formed at the bottom of the recess 32b of the motor shaft 32. The tap hole 32h is formed so as to be recessed from the bottom surface of the recess 32b toward the anti-load side, and is open toward the load side.

A method of assembling the pinion shaft 34 using the above motor 12 will be described. First, as in the first embodiment, a semi-finished product 66 in which the pinion shaft 34 is not assembled to the motor shaft 32 is prepared.

Subsequently, the press-fitting bolt 74 is inserted into the insertion hole 34c of the pinion shaft 34 from the load side, and a part of the screw shaft portion 74a of the press-fitting bolt 74 is projected from the insertion hole 34c toward the counterload side. In this state, as shown in FIG. 8A, the screw shaft portion 74a of the press-fitting bolt 74 is inserted into the recess 32b of the motor shaft 32, and the screw shaft portion 74a is screwed into the tap hole 32h of the motor shaft 32. .. Here, the screw shaft portion 74a of the press-fitting bolt 74 has a larger protrusion dimension Lb from the insertion hole 34c of the pinion shaft 34 than the dimension La in the axial direction from the load side opening to the bottom surface of the recess 32b of the motor shaft 32. Is set to be. As a result, it is not necessary to press-fit the shaft portion 34a of the pinion shaft 34 into the recess 32b of the motor shaft 32 until the screw shaft portion 74a of the press-fit bolt 74 is screwed into the tap hole 32h of the motor shaft 32.

After that, as shown in FIG. 8B, a rotational force Fc in the screw tightening direction is applied to the press-fitting bolt 74, and the screw shaft portion 74a of the press-fitting bolt 74 is screwed into the tap hole 32h by the rotational force Fc. When a rotational force Fc in the screw tightening direction is applied to the press-fitting bolt 74, the rotational force Fc is directed to the counterload side by contact between the male screw of the screw shaft portion 74a of the press-fitting bolt 74 and the female screw of the tap hole 32h. Will be converted. This press-fitting Fd acts on the press-fitting bolt 74, and is applied to the pinion shaft 34 from the head 74b of the press-fitting bolt 74. By applying this pressure input Fd to the pinion shaft 34, the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32. After the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the press-fit amount of the pinion shaft 34 into the recess 32b increases as the amount of rotation of the press-fit bolt 74 in the screw tightening direction increases.

After the pinion shaft 34 is press-fitted until it hits the bottom surface of the recess 32b of the motor shaft 32, the press-fitting bolt 74 is rotated in the direction opposite to the screw tightening direction. The press-fit bolt 74 is rotated until the screw shaft portion 74a of the press-fit bolt 74 comes out from the tap hole 32h of the motor shaft 32. After that, the screw shaft portion 74a of the press-fitting bolt 74 is pulled out from the insertion hole 34c of the pinion shaft 34. In addition to this, the press-fitting bolt 74 may be left screwed into the tap hole 32h, or may be held in a state of being inserted into the insertion hole 34c of the pinion shaft 34 by using another member.

Here, when the press-fitting bolt 74 is screwed into the tap hole 32h of the motor shaft 32, the reaction force Fe of the press-fitting input Fd acting on the press-fitting bolt 74 acts. This reaction force Fe acts toward the load side (upper side in the figure) opposite to the pressure input Fd toward the counterload side (lower side in the figure), and cancels out with the pressure input Fd. Therefore, according to the present embodiment, when the pinion shaft 34 is press-fitted, the press-fitting Fd acting on the motor shaft 32 from the pinion shaft 34 is canceled by the reaction force Fe acting on the motor shaft 32 from the press-fitting bolt 74. As a result, the thrust load Fa acting on the load side bearing 36 can be reduced. Therefore, also in this embodiment, the pinion shaft 34 can be press-fitted into the recess 32b of the motor shaft 32 while suppressing the load on the bearing on the counterload side 38, which can be useful for improving the productivity of the motor 12.

Further, in the present embodiment, when the pinion shaft 34 is press-fitted into the recess 32b of the motor shaft 32, the load receiving member 64 described in the above-described embodiment can be eliminated. Further, in the present embodiment, the pinion shaft 34 can be easily press-fitted into the recess 32b of the motor shaft 32 by a simple configuration in which the insertion hole 34c of the pinion shaft 34 and the tap hole 32h of the motor shaft 32 are combined.

The examples of the embodiments of the present invention have been described in detail above. All of the above-described embodiments are merely specific examples for carrying out the present invention. The content of the embodiment does not limit the technical scope of the present invention, and many design changes such as changes, additions, and deletions of components are made without departing from the idea of the invention defined in the claims. It is possible. In the above-described embodiment, the contents that can be changed in such a design are described with the notations such as "in the embodiment" and "in the embodiment", but the contents are designed without such notations. It's not that changes aren't tolerated. Further, the hatching attached to the cross section of the drawing does not limit the material of the object to which the hatching is attached.

Although the example in which the motor 12 is integrated with the speed reducer 14 has been described, it does not have to be integrated with the speed reducer 14. The speed reduction mechanism 20 of the speed reducer 14 has been described by taking a distribution type eccentric swing speed reduction mechanism as an example, but the type thereof is not particularly limited. For example, a simple planetary planetary gear reduction mechanism or the like may be used. Although the example in which the pinion shaft 34 transmits the rotational power to the reduction mechanism 20 of the reduction gear 14 has been described, the rotational power may be transmitted to the driven device.

Although the example in which the motor 12 includes the second counterload side cover 48 has been described, the motor 12 may not include the second counterload side cover 48. In this case, in order to obtain the effect described in the first embodiment, the anti-load side end surface 32d of the motor shaft 32 serving as the load transmission structure 40 is located on the anti-load side of the first anti-load side cover 46, which is the external space 58. It suffices if it is exposed to. Further, in order to obtain the effect described in the second embodiment, the protruding member mounted on the mounting portion of the motor shaft 32 should be exposed to the external space 58 on the counterload side of the first counterload side cover 46. Just do it.

The load transmission structure 40 described in the first to fourth embodiments and the combination of the insertion hole 34c of the pinion shaft 34 and the tap hole 32h of the motor shaft 32 described in the fifth embodiment are other embodiments. It may be combined with the one described in. For example, as described in the second embodiment, the mounting portion is provided on the counterload side end surface 32d of the motor shaft 32, and is held by the load side portion of the motor shaft 32 as described in the third and fourth embodiments. A part may be provided. Further, even if the combination of the insertion hole 34c of the pinion shaft 34 and the tap hole 32h of the motor shaft 32 as described in the fifth embodiment is used while providing the mounting portion on the counterload side end surface 32d of the motor shaft 32. good.

An example in which the rotation angle detection device 62 is arranged around the counterload side end portion 32c of the motor shaft 32 has been described. The arrangement position of the rotation angle detection device 62 is not particularly limited, and may be housed in the motor casing 30, for example. Further, the motor 12 does not have to include the rotation angle detecting device 62. Further, the rotation angle detection device 62 has been described by taking a rotary encoder as an example, but the specific example thereof is not particularly limited, and for example, a resolver or the like may be used.

12 ... Motor, 32 ... Motor shaft, 32a ... Load side end, 32b ... Recess, 32d ... Non-load side end face, 32h ... Tap hole, 34 ... Pinion shaft, 34c ... Insert hole, 36 ... Load side bearing, 38 ... Anti-load side bearing, 40 ... load transmission structure, 44 ... load side cover, 46 ... first anti-load side cover, 48 ... second anti-load side cover, 58 ... external space, 64 ... load receiving member, 72 ... Contact member.

Claims (11)

A motor shaft with a recess at the load side end,
The pinion shaft pushed into the recess and
A motor including a load-side bearing and a non-load-side bearing that support the motor shaft.
It is provided with a load transmission structure for allowing a thrust load acting on the motor shaft toward the counterload side to be transmitted to a load receiving member other than the load side bearing and the counterload side bearing.
A first counterload side cover for supporting the counterload side bearing is provided.
The load transmission structure is an end face on the anti-load side of the motor shaft exposed to an external space on the anti-load side of the first anti-load side cover.
A second counterload side cover that covers the counterload side end face of the motor shaft is provided.
A motor whose anti-load side end surface of the motor shaft having the load transmission structure is exposed to an external space on the anti-load side of the first anti-load side cover when the second anti-load side cover is not provided. The motor according to claim 1, wherein the second counterload side cover is detachably attached to the first counterload side cover. The motor according to claim 2, wherein the second counterload side cover is attached to the counterload side wall surface of the first counterload side cover with bolts. The motor according to any one of claims 1 to 3, wherein the counterload side bearing is fixed to the motor shaft by tightening and fitting. The motor according to any one of claims 1 to 4, wherein the counterload side bearing is fitted into the first counterload side cover by gap fitting. The motor according to any one of claims 1 to 5, wherein a cooling fan is not mounted on the opposite end of the motor shaft. The motor according to any one of claims 1 to 6, wherein the end face on the counterload side of the motor shaft projects to the counterload side from the first counterload side cover. The method for manufacturing a motor according to claim 1.
When the second anti-load side cover is not attached, the load is such that the anti-load side end face of the motor shaft exposed to the external space on the anti-load side of the first anti-load side cover is arranged in the external space. A method for manufacturing a motor, which comprises a press-fitting step of press-fitting the pinion shaft into the recess in a state of being in contact with a receiving member. The motor according to claim 8, wherein the press-fitting step is performed in a state where at least the stator, the rotor, the motor shaft, the load side bearing, the counterload side bearing, and the first counterload side cover are assembled to the motor casing. Manufacturing method. The method for manufacturing a motor according to claim 8 or 9, wherein the press-fitting step is performed by using a press die arranged inside the casing member in a state where the casing member of the speed reducer is assembled to the motor. The method for manufacturing a motor according to any one of claims 8 to 10, further comprising a cover attaching step of attaching the second counterload side cover to the first counterload side cover after performing the press-fitting step.

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