JP6964135B2 - Motor and how to assemble the motor - Google Patents

Description

The present invention relates to an electric motor, and more particularly to an electric motor configured so as to close an opening of a metal motor housing containing a stator and a rotor with a cover plate made of synthetic resin, and a method for assembling the electric motor.

Motors are used in various industrial fields, but in particular, motors for automobiles need to be lighter, so the stator and rotor are housed in a metal motor housing formed by squeezing an iron plate into a cylindrical shape. The opening of the motor housing is closed with a cover plate made of synthetic resin. By adopting such a configuration, the weight of the motor can be reduced, which contributes to the improvement of the fuel efficiency of the automobile.

By the way, an electric motor for an automobile is placed under various environmental conditions in order to perform various control operations of the automobile. For example, in an electric motor (electric braking device) that drives a caliper that brakes a wheel brake disc, an electric motor (electric power steering device) that assists steering of front wheels, etc., the waterproof function is particularly important because they are placed in the external environment. be.

Therefore, for example, in Japanese Patent Application Laid-Open No. 2013-62899 (Patent Document 1), a synthetic resin substrate case (= cover plate) is arranged in the opening of the metal motor case (= motor housing). An O-ring for sealing is arranged in an annular groove formed on the outer peripheral surface of the substrate case to provide a waterproof function. By interposing an O-ring in the contact area between the motor case and the outer peripheral surface of the substrate case in this way, it is possible to prevent muddy water, salt water, etc. from entering the motor housing, and to prevent the motor from malfunctioning. I try to avoid it.

Japanese Unexamined Patent Publication No. 2013-62899

By the way, not limited to the motor described in Patent Document 1 described above, when the cover plate that closes the opening of the motor housing is manufactured by injection molding synthetic resin, the synthetic resin “sink” at the time of molding the cover plate. , Etc. cause a phenomenon such as a decrease in roundness. Therefore, with the cover plate incorporated in the opening of the motor housing, it is inserted into a bearing (rolling bearing or slide bearing) provided near the center of the cover plate due to the effect of the reduced roundness of the cover plate. There is a risk that the rotating shaft of the rotor will tilt. Since a control mechanism to be controlled is connected to the rotating shaft (output side) of the rotor, if the rotating shaft is tilted, there arises a problem that abnormal noise is generated at this connected portion.

An object of the present invention is to provide a novel electric motor capable of suppressing the inclination of the rotating shaft of the rotor to reduce the generation of abnormal noise, and a method for assembling the electric motor.

The features of the present invention are a sealing region in which a sealing member is arranged on the outer peripheral surface of a synthetic resin cover plate that closes an opening of a metal motor housing, and a protrusion outward in the radial direction from the opening of the motor housing. A press-fitting region is formed in which at least three or more protruding press-fitting portions are provided, and the protruding press-fitting portion is deformed in a state where the cover plate is press-fitted into the opening of the motor housing to form the axial center of the motor housing and the cover plate. It is in the place where the axes are aligned.

According to the present invention, by deforming the protruding press-fitting portion, the axis of the motor housing and the axis of the cover plate can be aligned with each other. Occurrence can be reduced.

It is sectional drawing which shows the vertical cross section in the axial direction of the electric motor which becomes the typical embodiment of this invention. FIG. 5 is an enlarged cross-sectional view of a partially enlarged press-fitting portion of the motor housing and cover plate of the motor shown in FIG. 1. It is a perspective view which shows the state (rotor is omitted) before press-fitting of the motor housing and the cover plate of the motor which becomes the embodiment of this invention. It is a perspective view which shows the shape of the protruding press-fitting part provided in the cover plate. It is sectional drawing which shows the 1st cross-sectional shape in the axial direction of the protrusion press-fitting part provided on the cover plate. It is sectional drawing which shows the 2nd sectional shape in the axial direction of the protrusion press-fitting part provided on the cover plate.

The embodiments of the present invention will be described in detail with reference to the drawings, but the present invention is not limited to the following embodiments, and various modifications and applications thereof are also included in the technical concept of the present invention. It is included in the range. Hereinafter, typical examples of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an axial cross section of a brushed DC motor MTR, which is a typical embodiment of the present invention.

In FIG. 1, a permanent magnet 11 arranged in an annular shape forming a field magnet is fixed to an inner wall portion of a motor housing 10 in which an iron plate is formed into a substantially cylindrical shape by press working or the like. The motor housing 10 and the permanent magnet 11 form a stator 12 of the DC motor MTR. Inside the permanent magnets 11 arranged in an annular shape, a rotor 13 facing the permanent magnets 11 via a minute gap is arranged.

The rotor 13 has a laminated core 14 formed by laminating a die-cut silicon steel plate or the like, and a winding 15 wound around a salient pole formed on the laminated core 14. The outer surface of the laminated core 14 is molded with a thermosetting resin to ensure shape stability and insulation. The laminated core 14 around which the winding 15 is wound is fixed to the rotating shaft 16, and as the rotating shaft 16 rotates, a control mechanism (not shown) attached to the output side end portion 16A of the rotating shaft 16 Rotate and drive the driven member.

The bearing end 16B on the side opposite to the output side end 16A of the rotating shaft 16 is formed on the rear end bearing holding portion 17 formed by press working or the like at the center of the bottom 10B (lower end side in FIG. 1) of the motor housing 10. It is supported by the rear end side rolling bearing 18 held. In the present embodiment, the rear end bearing holding portion 17 is formed in a shape protruding inward of the motor housing 10. Serrations (not shown in this embodiment) are formed on the output side end 16A of the rotating shaft 16, or a reduction gear or the like is fixed to drive the driven member or decelerate (accelerate) the driven member. Used to drive.

In the present embodiment, the motor housing 10 is formed by pressing an iron plate, but an iron yoke may be arranged inside a cylindrical housing made of an aluminum alloy or the like. The description will be described as the motor housing 10, including the motor housing 10 and the combination of the housing and the yoke made of aluminum alloy or the like.

A commutator 19 is attached to the rotating shaft 16 in order to supply electric power to the winding 15, and a brush 20 for supplying electric power to the commutator 19 is attached to the cover plate 21. The cover plate 21 is made of polybutylene terephthalate (PBT) resin, which is a thermoplastic engineering plastic.

The cover plate 21 is press-fitted and fitted into the circular opening 10A orthogonal to the axial direction of the side peripheral portion 10S of the motor housing 10. That is, on the circular outer peripheral surface of the cover plate 21, an annular side wall 21W extending along the side peripheral portion 10S of the motor housing 10, in other words, extending in the axial direction of the rotation axis is formed, and this annular side wall 21W is the motor. It is press-fitted and fitted to the inner peripheral surface of the side peripheral portion 10S of the housing 10.

A front end side rolling bearing 22 is fixed to the central portion of the cover plate 21, and a rotating shaft 16 is inserted to rotatably support the rotating shaft 16. It is also possible to use a plain bearing instead of the rolling bearing. Further, two brushes 20 described above are arranged between the rotor 13 and the cover plate 21 at an angle of 180 °. The two brushes 20 are pressed and urged by a coil spring (not shown) on the commutator 19.

A seal region SL and a press-fitting region PF are formed in a predetermined region PP of the side peripheral portion 10S extending axially from the opening 10A of the motor housing 10 in cooperation with the cover plate 21.

The seal region SL is an O-ring 23 arranged in a seal groove formed on the inner peripheral surface of the side peripheral portion 10S of the motor housing 10 and the outer peripheral surface of the annular side wall 21W of the cover plate 21 extending along the side peripheral wall 10S. It is formed by. Further, a press-fitting region PF is formed between the sealing region SL and the opening 10A. The press-fitting region PF is formed by an inner peripheral surface of the side peripheral portion 10S of the motor housing 10 and a protruding press-fitting portion 24 (see FIGS. 2 to 4) provided along the outer peripheral surface of the annular side wall 21W of the cover plate 21. Has been done.

Then, in the present embodiment, the protruding press-fitting portion 24 provided along the outer peripheral surface of the annular side wall 21W of the cover plate 21 is deformed while being press-fitted into the opening 10A of the motor housing 10 to cover the motor housing 10 and the cover. It is characterized in that the axes of the plates 21 are aligned with each other. Hereinafter, this point will be described in detail with reference to FIGS. 2 to 5.

In FIG. 2, an O-ring 23 housed in a seal groove is arranged on the outer peripheral surface of the end portion of the annular side wall 21W of the cover plate 21 on the winding 15 side. Further, the protruding press-fitting portion 24 is formed so as to be closer to the opening 10A side with respect to the O-ring 23 and separated by a predetermined distance. The protruding press-fitting portion 24 is formed in a portion of the annular side wall 21W having a long thickness. More preferably, it is formed near the root of the annular side wall 21W that bends in the axial direction from the cover plate 21. With this configuration, it is possible to prevent the annular side wall 21W from being deformed when the projecting press-fitting portion 24 is press-fitted into the opening 10A as described later.

Further, as shown in FIGS. 3 and 4, the protruding press-fitting portion 24 projects radially outward from the outer peripheral surface 21F of the annular side wall 21W, and is located at the center position of the cover plate 21 (the axial center of the front end side rolling bearing 22). The length from) to the outer surface of the protruding press-fitting portion 24 is set to be larger than the radius of the opening 10A of the side peripheral portion 10S of the motor housing 10. Therefore, when the annular side wall 21W of the cover plate 21 is press-fitted into the opening 10A of the side peripheral portion 10S of the motor housing 10, the protruding press-fitting portion 24 is deformed (or scraped off), and as a result, the motor housing 10 is formed. It is in a form of being in close contact with the opening 10A of the side peripheral portion 10S of the above.

Here, the amount of protrusion toward the outside in the radial direction of the protrusion press-fitting portion 24, but if the amount of protrusion is made larger than necessary, the gap between the O-ring 23 and the inner peripheral surface of the side peripheral portion 10S of the motor housing 10 May be enlarged and the sealing function may be reduced or lost. For this reason, the O-ring 23 is determined to have a protrusion amount that allows a deformation allowance that allows appropriate compression deformation to ensure sealing performance with respect to the inner peripheral surface of the side peripheral portion 10S of the motor housing 10.

Further, in relation to this, if the amount of protrusion is increased as described above, the opening 10A of the side peripheral portion 10S of the motor housing 10 may be plastically deformed. Therefore, the amount of protrusion is determined so that the annular side wall 21W of the cover plate 21 can be elastically press-fitted and held in the fitted state while the opening 10A is elastically deformed.

It should be noted that at least three or more protruding press-fitting portions 24 are provided on the outer peripheral surface 21F of the annular side wall 21W at equal intervals, and needless to say, they are integrally formed of the same material as the cover plate 21. In the present embodiment, only six protruding press-fitting portions 24 are provided on the outer peripheral surface 21F of the annular side wall 21W at equal intervals (60 ° intervals), but if the number is too large, the press-fitting load for press-fitting is provided. Is large, which may cause deformation of the opening 10A of the motor housing 10, so it is rational to keep the number in the range of 3 to 6.

Further, the cross-sectional shape of the protruding press-fitting portion 24 toward the outside in the radial direction may be a shape such as a rectangle, a triangle, or a trapezoid, but in the present embodiment, as shown in FIG. 4, a predetermined length in the circumferential direction. It is formed in a trapezoidal shape having an arcuate surface 24F having a diameter L. As a result, the frictional force with the inner peripheral surface of the side peripheral portion 10S of the motor housing 10 is increased, the rotation of the cover plate 21 is suppressed at the opening 10A of the motor housing 10, and the cover plate 21 is covered in the axial direction. The plate 21 is prevented from coming off.

If necessary, it is also possible to form a rotation stopper separately from the protruding press-fitting portion 24 to reliably avoid the rotation of the cover plate 21. Further, inclined portions 24S formed at both ends of the protruding press-fitting portion 24 in the circumferential direction are provided in order to suppress unnecessary deformation of the protruding press-fitting portion 24.

Further, as shown in FIG. 5A, the protruding press-fitting portion 24 formed on the annular side wall 21W is formed so as to include a tapered shaped portion 24T inclined from the arcuate surface 24F in the press-fitting direction. As a result, when the annular side wall 21W of the cover plate 21 is press-fitted into the opening 10A of the side peripheral portion 10S of the motor housing 10, the press-fitting load is applied evenly. Further, instead of the protruding press-fitting portion 24 as shown in FIG. 5A, the arc-shaped surface 24F shown in FIG. 5A may not be formed on the protruding press-fitting portion 24 as shown in FIG. 5B.

Next, the shape of the side peripheral portion 10S of the motor housing 10 near the opening 10A will be described. Returning to FIG. 2, the side peripheral wall 10S of the motor housing 10 may be basically formed in a straight cylinder shape having a constant diameter toward the opening 10A. However, if the thickness of the motor housing 10 is made thin, the opening 10 may be expanded outward by the protruding press-fitting portion 24 while the cover plate 21 is press-fitted into the opening 10A. Therefore, the compressed state of the O-ring 23 may change between the side peripheral wall 10S of the motor housing 10 and the O-ring 23, and the sealing performance may deteriorate.

On the other hand, in the present embodiment, the side peripheral wall 10S of the motor housing 10 is formed in a stepped shape with a radius set gradually larger toward the opening 10A. That is, the radius of the side peripheral wall 10SL2 located in the press-fitting region PF is set to be larger than the radius of the side peripheral wall 10SL1 located in the seal region SL. Therefore, the connecting portion between the side peripheral wall 10SL1 and the side peripheral wall 10SL2 is a step portion 25.

Therefore, even if the cover plate 21 is press-fitted into the opening 10A of the side peripheral wall 10S, the expansion operation of the opening 10A by the protruding press-fitting portion 24 is buffered by the step portion 25, and the side peripheral wall 10SL1 located in the seal region SL1 Is suppressed. Therefore, it is possible to reduce the possibility that the compression state of the O-ring 23 is suppressed from changing between the side peripheral wall 10S of the motor housing 10 and the O-ring 23, and the sealing performance is deteriorated.

After the cover plate 21 is press-fitted into the motor housing 10, the cover plate 21 can be prevented from coming off from the motor housing 10 by a separately formed retaining member. For example, the cover plate 21 can be prevented from coming off by forming a bent portion in a part of the motor housing 10 and bending it toward the cover plate 21 side. Further, when combined with other devices, the cover plate 21 can be prevented from coming off by using the other devices.

Next, a method of assembling the motor housing 10 and the cover plate 21 according to the present embodiment will be described.

First, before assembling, the permanent magnet 11 and the rear end side rolling bearing 18 are fixed and integrated with the motor housing 10, and similarly, the front end side rolling bearing 22 is fixed and integrated with the cover plate 21. back. In this case, the front end side rolling bearing 22 can be simultaneously molded by insert molding when molding the cover plate 21.

Next, the rotating shaft 16 to which the rotor 13 is fixed is arranged in the motor housing 10. Since the outer ring of the rear end side rolling bearing 18 is press-fitted and fixed to the rear end bearing holding portion 17 of the motor housing 10, the bearing end 16B of the rotating shaft 16 is press-fitted into the inner ring of the rear end side rolling bearing 18. As a result, one end of the rotating shaft 16 can be rotatably supported by the motor housing 10.

Next, the inner ring of the front end side rolling bearing 22 fixed to the cover plate 21 is press-fitted into the rotating shaft 16, and at the same time, the cover plate 21 is press-fitted into the opening 10A of the motor housing 10. At this time, the motor housing 10 is held by the motor housing side hire (not shown), and the axis of the motor housing side hire substantially coincides with the axis of the opening 10A (= the regular axis of the rotating shaft 16). There is. Similarly, the cover plate 21 is held by a cover plate side employee (not shown), and the axis of the cover plate side employee is substantially aligned with the axis of the motor housing side employee. The axis of the cover plate side is substantially the same as the regular axis of the front end side rolling bearing 22.

In this way, by hiring the cover plate side, the inner ring of the front end side rolling bearing 22 fixed to the cover plate 21 is press-fitted into the rotating shaft 16, and at the same time, the cover plate 21 is press-fitted into the opening 10A of the motor housing 10. Then, the press-fitting proceeds in a state where the axis of the opening 10A and the axis of the front end side rolling bearing 22 are aligned. Therefore, if the roundness of the protruding press-fitting portion 24 is deviated, the protruding press-fitting portion 24 is press-fitted while being deformed (or scraped off) by the opening 10A.

Then, when the assembly is completed, the axis of the motor housing 10 and the axis of the cover plate 21 coincide with each other, so that the rotating shaft 16 also coincides with these axes. Therefore, as a result, the inclination of the rotating shaft 16 of the rotor 13 can be suppressed, and the generation of abnormal noise can be reduced. Further, since the other actions and effects of the present embodiment are as described above, further description thereof will be omitted here.

In the conventional one, if the roundness is lowered due to the “sink” of the synthetic resin at the time of molding the cover plate 21, the roundness of the seal groove through which the O-ring 23 is interposed is also lowered, so that the O-ring is also lowered. There is also a problem that good sealing performance cannot be ensured due to variations in the compression allowance of 23. However, in the present embodiment, since the axis of the motor housing 10 and the axis of the cover plate 21 coincide with each other, it is possible to compensate for the decrease in roundness of the seal groove in which the O-ring 23 is interposed, so that the sealability can be improved. It is also possible to improve.

Although the brushed DC motor has been described in the above-described embodiment, the present invention is not limited to this, as long as the opening of the motor housing is closed with a cover plate made of synthetic resin. It can also be applied to various motors such as brushless motors.

Further, in the above-described embodiment, the seal region is arranged on the winding side with respect to the press-fit region, but on the contrary, the press-fit region is arranged on the winding side with respect to the seal region. Is also a problem.

As described above, according to the present invention, there is a sealing region in which a sealing member is arranged on the outer peripheral surface of a synthetic resin cover plate that closes an opening of a metal motor housing, and a radial direction from the opening of the motor housing. A press-fitting region is formed in which at least three protruding press-fitting portions are provided so as to project outward, and the protruding press-fitting portion is deformed with the cover plate press-fitted into the opening of the motor housing to deform the shaft of the motor housing. The structure is such that the center and the axis of the cover plate are aligned.

According to this, by deforming the protruding press-fitting portion, the axis of the motor housing and the axis of the cover plate can be aligned, and as a result, the inclination of the rotation axis of the rotor can be suppressed and abnormal noise is generated. Can be reduced.

The present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiment has been described in detail in order to explain the present invention in an easy-to-understand manner, and is not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

10 ... Motor housing, 11 ... Permanent magnet, 12 ... Stator, 13 ... Rotor, 14 ... Laminated core, 15 ... Winding, 16 ... Rotating shaft, 17 ... Rear end shaft house holding part, 18 ... Rear end side cartwheel bearing , 19 ... commutator, 20 ... brush, 21 ... cover plate, 21W ... annular side wall, 22 ... front end side rolling bearing, 23 ... O-ring, 24 ... protruding press-fitting part.

Claims (7)

A metal motor housing having an opening on one side and formed in a cylindrical shape, a cover plate made of synthetic resin that closes the opening, a stator fixed in the motor housing, and a stator arranged in the stator. An electric motor composed of a rotor having a rotating shaft that is exposed to the outside through the cover plate.
A seal region in which a seal member is arranged on the outer peripheral surface of the cover plate that closes the opening of the motor housing, and at least three or more protrusions that project radially outward from the opening of the motor housing. A press-fit area provided with a press-fit portion is formed,
Side wall of the opening of the motor housing, as compared to the radius of said side wall positioned in the seal area, by Rukoto the radius of it is set large in the peripheral wall positioned in the press-fitting area, the seal A step portion is formed between the side peripheral wall of the motor housing facing the member and the side peripheral wall of the motor housing facing the protruding press-fitting portion.
In a state where the cover plate is press-fitted into the opening of the motor housing, the protruding press-fitting portion is deformed to align the axial center of the motor housing with the axial center of the cover plate, and the protruding press-fitting portion is used. An electric motor characterized in that the opening operation of the opening is buffered by the step portion. In the motor according to claim 1,
An electric motor characterized in that an annular side wall extending in the axial direction of the rotation shaft is formed on the outer peripheral surface of the cover plate, and the seal region and the press-fitting region are formed on the outer peripheral surface of the annular side wall. .. In the motor according to claim 2,
The motor is characterized in that the seal region is formed at a position on the annular side wall on the side of the rotor, and the press-fit region is formed at a position between the seal region and the opening of the annular side wall. In the motor according to claim 3,
An electric motor characterized in that three or more protruding press-fitting portions provided in the press-fitting region are formed on the outer peripheral surface of the annular side wall at equal intervals. In the motor according to claim 4,
An electric motor characterized in that the distal end surface of the protruding press-fitting portion in the radial direction is formed into an arcuate surface having a predetermined length extending along the circumferential direction. In the motor according to claim 5,
The protruding press-fitting portion is an electric motor including a tapered portion that is inclined from the arcuate surface in the press-fitting direction. A metal motor housing having an opening on one side and formed in a cylindrical shape, a cover plate made of synthetic resin that closes the opening, a stator fixed in the motor housing, and a stator arranged in the stator. , A method of assembling an electric motor composed of a rotor provided with a rotating shaft that is exposed to the outside through the cover plate.
The outer peripheral surface of the cover plate that closes the opening of the motor housing has a sealing region in which a sealing member is arranged and at least three or more protrusions that project radially outward from the opening of the motor housing. A press-fitting region provided with a press-fitting portion is formed, and a press-fitting region is formed.
The side peripheral wall of the opening of the motor housing is set so that the radius of the side peripheral wall located in the press-fitting region is larger than the radius of the side peripheral wall located in the seal region. A step portion is formed between the side peripheral wall of the motor housing facing the member and the side peripheral wall of the motor housing facing the protruding press-fitting portion.
Hold the cover plate in the cover plate hire,
The motor housing in which the stator and the rotating shaft fixing the rotor are housed is held by the motor housing.
With the axis of the cover plate and the axis of the motor housing aligned, the cover plate is press-fitted into the opening of the motor housing, and the protruding press-fitting portion follows the shape of the opening. The motor housing is deformed so that the axis of the motor housing and the axis of the cover plate are aligned with each other, and the opening operation of the opening by the protruding press-fitting portion is buffered by the step portion for assembly.
A method of assembling an electric motor, which is characterized in that.

Images