JP4490891B2 - Manufacturing method of electric motor - Google Patents

Description

  The present invention relates to a method of manufacturing an electric motor configured such that a rotating shaft and a bearing or a motor housing and a bearing are in close contact with each other.

  In recent years, as a power steering device for reducing the steering force of a steering wheel (steering wheel), an electric power steering device that uses the power of an electric motor instead of a conventional hydraulic type is adopted in many vehicles. The electric power steering apparatus generally assists a driver's steering operation by boosting the rotational torque of an electric motor by a speed reduction mechanism and applying the torque to a rack shaft via a rack and pinion mechanism. As such an electric power steering device, conventionally, only one end side of the rotating shaft of the electric motor is fixedly supported in the axial direction of the rotating shaft by a bearing in the motor housing, and the other end side is supported in the motor housing. The thing of the structure which does not carry out is known (refer patent document 1).

  However, the above-described structure has a problem that when the rotating shaft is rotated at a high speed, a large centrifugal force is applied to the other end of the rotating shaft that is not supported by the bearing, and the rotating shaft vibrates. In order to solve such a problem, the inventor of the present application supports both ends of the rotating shaft in the motor housing with bearings, and press-fits the inner ring and outer ring of the bearing into the rotating shaft and the motor housing so as to closely contact each other without any gap. A structure was created (see Patent Document 2). According to this, it is possible to suppress the vibration of the rotating shaft.

JP 2002-284023 A (paragraph 0019, FIG. 1) Japanese Patent Application No. 2005-81958

  However, in the technique created by the inventor described above, for example, as shown in FIG. 8, when the bearing 91 attached to the rotating shaft 90 is press-fitted into the bearing attachment portion 92 a of the motor housing 92, the outer ring 93 of the bearing 91 is There is a possibility that the inner ring 94 may be attached to be inclined. When the outer ring 93 of the bearing 91 is tilted with respect to the inner ring 94 in this way, the fluctuation of the friction torque of the motor increases, and this is boosted by the speed reduction mechanism and transmitted to the steering wheel. There have been problems of worsening (for example, problems such as worsening of steering wheel return and feeling of torque fluctuation during steering operation). Furthermore, the vibration generated in the rotating shaft is transmitted to the gear housing that houses the speed reduction mechanism connected to the motor housing, and noise may be generated from the gear housing.

  Therefore, an object of the present invention is to provide a method of manufacturing an electric motor that suppresses noise and suppresses the inclination of the outer ring or inner ring of the bearing that occurs during assembly, thereby contributing to ensuring good steering feeling. .

The invention according to claim 1 of the present invention that solves the above-mentioned problems includes a rotor having a rotating shaft, a first bearing and a second bearing that support both ends of the rotating shaft, and the rotating shaft is the first. A method of manufacturing an electric motor, comprising: a first housing attached via a bearing; a second housing to which a stator is fixed; and a bearing attachment portion for attaching the second bearing to the second housing. A stator assembling step for assembling the stator to the second housing, a bearing assembling step for assembling the first bearing and the second bearing to the rotating shaft, and press fitting the first bearing into the first housing. a step of assembling, the performed, thereafter, the second performs at least the bearing mounting portion heating step of expanding heated to a radial direction of the housing, thereafter, it said bearing mounting portion inflated, the holding means There is performed an arrangement step of arranging via a predetermined gap and the second bearing held in the radial direction, thereafter, at least said shrunk by cooling the bearing mounting portion, the said bearing mounting portion first A cooling process for fixing the two bearings is performed .

According to the first aspect of the invention, in the stator assembling step, the stator is assembled to the second housing, and in the bearing assembling step, the first bearing and the second bearing are assembled to both ends of the rotating shaft , and thereafter Ru assembled by press-fitting the first bearing in the first housing. Further, in the heating step, for example, the bearing mounting portion is expanded in the radial direction by heating the entire second housing, and in the disposing step, the expanded bearing mounting portion and the second bearing held using the holding means Are arranged in the radial direction through a predetermined gap. And in a cooling process, a 2nd bearing will be fixed to this bearing attachment part by shrinking a bearing attachment part, for example by cooling the 2nd housing whole. That is, although the force in the radial direction is applied to the outer ring of the second bearing attached to the rotating shaft by the shrinking bearing mounting portion, but the force in the axial direction is not applied, the outer ring of the second bearing Will be suppressed.

A second aspect of the present invention is the method of manufacturing the electric motor according to the first aspect, wherein the heating step heats the entire second housing.

A third aspect of the present invention is the method of manufacturing the electric motor according to the first aspect, wherein the second housing is formed of a single member.

According to a fourth aspect of the present invention, there is provided a rotor having a rotating shaft, a first bearing and a second bearing that support both ends of the rotating shaft, and the rotating shaft attached via the first bearing. 1. A method of manufacturing an electric motor, comprising: a housing; a second housing to which a stator is fixed; and a bearing attachment portion for attaching a second bearing to the second housing, wherein the stator is attached to the second housing. a stator assembling step of assembling and a step with the rotation shaft side bearing assembly is assembled the first bearing at one end of the rotary shaft, and a second housing side bearing assembly step of assembling the second bearing in the second housing, wherein holds by the outer peripheral portion of the second housing in which the second bearing is assembled first holding means, the inner race of the second the second bearing assembled in the housing and held by the second holding means, both And having a press-fitting step of press-fitting the other end of the rotary shaft relative to the inner ring of the second bearing while holding the state.

According to the fourth aspect of the present invention, the stator is assembled to the second housing in the stator assembling step, and the first bearing is assembled to one end of the rotating shaft in the rotating shaft side bearing assembling step. Then, in the second housing side bearing assembly process, the second bearing is assembled to the second housing , and in the press-fitting process, the outer periphery of the second housing assembled with the second bearing is held by the first holding means, (2) The inner ring of the second bearing assembled to the housing is held by the second holding means, and the other end of the rotary shaft is press-fitted into the inner ring of the second bearing while both are held. Thereby, the inclination of the inner ring of the second bearing when the rotary shaft is press-fitted into the second bearing is suppressed.

According to a fifth aspect of the present invention, there is provided a rotor having a rotating shaft, a first bearing and a second bearing that support both ends of the rotating shaft, and the rotating shaft attached via the first bearing. 1. A method of manufacturing an electric motor, comprising: a housing; a second housing to which a stator is fixed; and a bearing attachment portion for attaching a second bearing to the second housing, wherein the stator is attached to the second housing. A stator assembling step, a bearing assembling step for assembling the first bearing and the second bearing to the rotary shaft, and the bearing mounting portion and the second bearing arranged in a radial direction through a predetermined gap. And a plastic deformation step of fixing only the second bearing to the bearing mounting portion by plastically deforming the bearing mounting portion in a radial direction so as to contact the entire outer periphery of the outer ring of the second bearing. It is characterized by having .

According to the invention described in claim 5, in the stator assembling step, the stator is assembled to the second housing, and in the bearing assembling step, the first bearing and the second bearing are assembled to the rotating shaft. In the arranging step, the bearing mounting portion and the second bearing are arranged in a radial direction through a predetermined gap, and in the plastic deformation step, the bearing mounting portion is in contact with the entire outer periphery of the outer ring of the second bearing. The bearing mounting portion and the second bearing are fixed by plastically deforming in the radial direction. That is, although a radial force is applied to the outer ring of the second bearing attached to the rotating shaft by pressure bonding due to plastic deformation, no force is applied in the axial direction. The inclination is suppressed.

According to the first to third aspects of the invention, since the second bearing and the second housing can be assembled with high accuracy and the inclination of the outer ring of the second bearing can be suppressed, the cogging torque is reduced and good. As well as ensuring a good steering feeling, noise can be suppressed.

According to the fourth aspect of the present invention, since the inclination of the inner ring of the second bearing can be suppressed by assembling the second bearing and the rotating shaft with high accuracy, the cogging torque is reduced and a good steering feeling is achieved. It can be ensured and noise can be suppressed.

According to the fifth aspect of the invention, similarly to the effect of the first aspect of the invention, the second bearing and the second housing can be assembled with high accuracy to suppress the inclination of the outer ring of the second bearing. Therefore, the cogging torque can be reduced to ensure a good steering feeling, and noise can be suppressed.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to the drawings as appropriate. In the drawings to be referred to, FIG. 1 is a schematic configuration diagram showing an electric power steering apparatus including an electric motor manufactured by the manufacturing method according to the first embodiment, and FIG. 2 is a schematic cross-sectional view showing the electric motor of FIG. FIG. In the following, before describing the manufacturing method of the electric motor (electric motor) according to the present invention, the structure of the electric motor that is the object of the manufacturing method and the structure of the electric power steering device in which the electric motor is used. Will be described.

  As shown in FIG. 1, an electric power steering apparatus 1 includes a steering shaft 3 coupled to a steering wheel 2, a steering torque sensor 4 that detects steering torque that acts on the steering shaft 3, and a vehicle speed sensor 5 that detects vehicle speed. An electric motor 7 that applies a steering assist force to the steering shaft 3 via the speed reduction mechanism 6, a drive control device (ECU) 8 that controls the drive of the electric motor 7, and a rack and pinion mechanism 9. Rack shaft 10. A steered wheel (front wheel) 12 is connected to both ends of the rack shaft 10 (in the drawing, only one end side of the rack shaft 10 is illustrated) via a tie rod 11 and the like.

  The speed reduction mechanism 6 has a function of boosting the rotational torque of the electric motor 7 and transmitting it to the steering shaft 3. For example, a worm gear (not shown) provided on the rotation shaft (output shaft) 13 of the electric motor 7. And a worm wheel (not shown) provided on the steering shaft 3 are engaged with each other. In this embodiment, the electric motor 7 uses a brushless DC motor, and is connected to a gear housing (not shown) that houses the speed reduction mechanism 6, the rack and pinion mechanism 9, and the like. Details of the structure of the electric motor 7 will be described later. The rack and pinion mechanism 9 is configured by meshing pinion teeth 15 provided on a pinion shaft 14 connected to the steering shaft 3 and rack teeth 16 provided on the rack shaft 10.

  In the electric power steering apparatus 1 configured as described above, when the driver steers the steering wheel 2, the rack shaft 10 is linearly reciprocated via the rack and pinion mechanism 9 by the steering torque applied to the steering shaft 3. Then, the steered wheel 12 is steered through the tie rod 11 and the like. At this time, the drive control device 8 sets a target current value to be passed to the electric motor 7 based on the steering torque signal input from the steering torque sensor 4 and the vehicle speed signal input from the vehicle speed sensor 5, and this target current The electric motor 7 is driven by current feedback control so that the deviation between the value and the motor current value input from the motor current sensor 17 becomes zero. As a result, the electric motor 7 generates an appropriate steering assist force (assist force), and this steering assist force is applied to the steering shaft 3 via the speed reduction mechanism 6, whereby the steering force at the time of the driver's steering operation. Can be reduced.

<Configuration of electric motor>
As shown in FIG. 2, the electric motor 7 has two first and second motor housings 20a and 20b integrally connected to each other by a pair of first and second bearings 21 and 22 which are rolling bearings. A rotary shaft 13 that is rotatably supported on the side, a rotor (rotor) 23 that is integrally fixed to the rotary shaft 13, and a second motor housing so as to face the outer peripheral surface of the rotor 23 A plurality of stators (stator) 24 fixed to the inner peripheral surface of 20b and a resolver 25 for detecting the rotation angle of the rotor 23 are mainly provided. In the electric motor 7, the drive control device 8 (see FIG. 1) is configured so that the windings (coils) 26 of the stators 24 are based on the rotation angle detection signal of the rotor 23 input from the resolver 25. The rotor 23 (rotating shaft 13) is rotated by this rotating magnetic field by generating a rotating magnetic field by passing a current in a predetermined order.

  The first motor housing 20a is formed in a substantially bottomed cylindrical shape. A flange portion 20c extending outward is formed on the outer peripheral surface of the first motor housing 20a, and a bearing mounting portion for mounting the first bearing 21 on the bottom portion. 20d is formed. The flange portion 20c of the first motor housing 20a is fixed by a bolt or the like to a gear housing (not shown) that houses the speed reduction mechanism 6, the rack and pinion mechanism 9, and the like.

  The second motor housing 20b is formed in a substantially bottomed cylindrical shape, the bottom of the first motor housing 20a is fixed to the opening thereof, and the stator 24 is fixed to the inner peripheral surface thereof. A substantially bottomed cylindrical bearing mounting portion 20e for mounting the second bearing 22 at the center of the bottom is formed so as to bulge outward. An escape hole 20f that allows insertion of a centering jig 44 (see FIG. 3) used in the manufacturing method described later is formed at the bottom of the substantially bottomed cylindrical bearing mounting portion 20e. The hole 20f is appropriately closed with another component after the second bearing 22 is mounted on the bearing mounting portion 20e.

  The first bearing 21 includes a ring-shaped inner ring 27 that is press-fitted to the outer peripheral surface of the rotary shaft 13 without a gap, and a ring-shaped outer ring 28 that is press-fitted to the inner peripheral surface of the bearing mounting portion 20d of the first motor housing 20a without a gap. And a rolling element 29 that is rotatably held between the inner ring 27 and the outer ring 28. Similarly, the second bearing 22 is a ring-shaped inner ring 30 that is press-fitted to the outer peripheral surface of the rotary shaft 13 without a gap, and a ring that is press-fitted to the inner peripheral surface of the bearing mounting portion 20e of the second motor housing 20b without a gap. The outer ring 31 is shaped like a ring, and the rolling elements 32 are rotatably held between the inner ring 30 and the outer ring 31.

  Next, the manufacturing apparatus and manufacturing method of the electric motor 7 according to the first embodiment will be described. In the drawings to be referred to, FIG. 3 is a diagram showing a method of manufacturing the electric motor according to the first embodiment, and is a schematic cross-section showing a process of setting the first motor housing and the second motor housing in the electric motor manufacturing apparatus, respectively. FIG. 5A is a schematic cross-sectional view showing a step of arranging the thermally-expanded second motor housing bearing mounting portion around the second bearing, and a schematic showing a step of cooling and contracting the bearing mounting portion. It is sectional drawing (c).

First, the manufacturing apparatus of the electric motor 7 will be described.
As shown in FIG. 3A, the electric motor manufacturing apparatus 40 includes a base 41 for fixing the first motor housing 20 a to which the rotary shaft 13 is attached via the first bearing 21, and a base 41. Is mainly provided with a lifting mechanism 42 configured to be movable up and down, and a holding device 43 that holds the second motor housing 20b to which the stator 24 is fixed. The base 41 is provided with a centering jig 41a for centering the rotary shaft 13 and a coil spring 41b for urging it to the rotary shaft 13 side. The holding device 43 is a substantially bottomed cylindrical device that holds the second motor housing 20b so as to wrap the second motor housing 20b downward with a chuck mechanism such as a vacuum chuck. An escape hole 43a for escaping the centering jig 44 supported by the top wall or the like is formed.

Then, the manufacturing method of the electric motor 7 is demonstrated.
First, before setting the components of the electric motor 7 in the electric motor manufacturing apparatus 40 shown in FIG. 3A, the stator 24 is assembled to the second motor housing 20b in advance (stator assembling step) and rotated. First and second bearings 21 and 22 are assembled to both ends of the rotating shaft 13 of the child 23 (bearing assembling step), and further, the first bearing 21 is assembled to the first motor housing 20a. Here, the assembling order of the rotary shaft 13, the first bearing 21 and the first motor housing 20a can be changed as appropriate, but the mounting method (described later) prevents the inner ring 27 and the outer ring 28 of the first bearing 21 from tilting. For example, the attachment method by heating according to the present embodiment, the attachment method according to the second embodiment, and the like) need to be appropriately employed. Further, other parts (for example, resolver 25) and the like are appropriately assembled to the motor housings 20a and 20b.

  As described above, when the manufacture of the unit of the first motor housing 20a and the unit of the second motor housing 20b is completed, the unit of the second motor housing 20b is placed in a high-temperature heating furnace and heated to expand overall. (Heating process). Thereafter, the first motor housing 20a to which the rotary shaft 13 is attached via the first bearing 21 is fixed to the base 41, and the second motor housing 20b heated in the heating step is fixed by the holding device 43. Hold.

  Subsequently, as shown in FIG. 3B, the second motor housing 20 b held by the holding device 43 is lowered by the elevating mechanism 42, so that the bearing mounting of the second motor housing 20 b expanded in the radial direction is performed. The part 20e and the second bearing 22 fixed to the rotary shaft 13 are arranged in the radial direction via a predetermined gap (arrangement step). Then, after a predetermined time has elapsed, the second motor housing 20b is naturally cooled (cooling step), and as shown in FIG. 3C, the bearing mounting portion 20e gradually contracts in the radial direction, and the bearing The attachment portion 20e and the second bearing 22 are fixed. In FIG. 3, for the sake of convenience, only the thermal expansion / contraction of the bearing mounting portion 20e is illustrated, but actually, the portions other than the bearing mounting portion 20e are also similarly subjected to thermal expansion / contraction. In particular, the opening (lower opening) of the second motor housing 20b is thermally contracted so as to be fitted to the first motor housing 20a.

According to the above, the following effects can be obtained in the first embodiment.
Since the second bearing 22 is inserted into the bearing mounting portion 20e with a predetermined gap between the bearing mounting portion 20e of the second motor housing 20b and the second bearing 22, the outer ring of the second bearing 22 is inserted when the bearing is inserted. It can suppress that 31 contacts the bearing attaching part 20e and inclines. Even if the outer ring 31 of the second bearing 22 is inclined, the inclination of the outer ring 31 is corrected so as to follow the inner surface of the bearing mounting part 20e that contracts in the radial direction. 20e and the second bearing 22 can be fixed with high accuracy. Then, as described above, the inclination of the outer ring 31 of the second bearing 22 is suppressed, so that the productivity of the electric motor 7 is improved, the quietness is excellent, the handle return is good, and there is no torque fluctuation. It is possible to provide the electric power steering apparatus 1 having a steering feeling.

  In addition, since the bearing mounting portion 20e is arranged with a predetermined gap with respect to the second bearing 22 and then cooled, they are fixed in close contact with each other, so that compared with the manufacturing method having a press-fitting process. In addition, the time required for the press-fitting process can be shortened, a press-fitting device is not required, and the cost can be reduced.

The present invention is not limited to the first embodiment, and can be implemented in various forms.
In the first embodiment, the entire second motor housing 20b is heated and cooled. However, the present invention is not limited to this, and if at least the bearing mounting portion 20e of the second motor housing 20b is heated and cooled. Good.
In the first embodiment, the cooling of the second motor housing 20b is natural cooling. However, the present invention is not limited to this, and may be forced cooling such as air cooling by blowing air or water cooling by circulating cooling water.

[ First Reference Example ]
Below, the manufacturing method of the electric motor which concerns on the 1st reference example of this invention is demonstrated. Since this embodiment is obtained by changing a part of the electric motor manufacturing apparatus and manufacturing method of the first embodiment, the description of the same components and steps as those of the first embodiment is omitted. In the drawings to be referred to, FIG. 4 is a schematic sectional view showing a method for manufacturing an electric motor according to a first reference example .

As shown in FIG. 4, the electric motor manufacturing apparatus 40 ′ according to the first reference example is in a proper position near the tip of the centering jig 44 for centering the rotary shaft 13 on the second bearing 22 side. A point where the flange part 44 a is formed, a point where a spring member (holding means) 45 for holding the outer ring 31 of the second bearing 22 is provided between the flange part 44 a and the second bearing 22, and a bottom part of the holding device 43 This is different from the electric motor manufacturing apparatus 40 according to the first embodiment in that the escape hole 43a is formed in a size that does not interfere with the flange 44a. Here, the urging force (the amount of contraction) of the spring member 45 is set so that the end surface of the outer ring 31 of the second bearing 22 is maintained to be substantially parallel to the end surface of the inner ring 30.

Next, a method for manufacturing the electric motor 7 according to the first reference example will be described.
Similarly to the first embodiment, after performing the stator assembly process, the bearing assembly process, and the heating process, the first motor housing 20a and the second motor housing 20b are set on the base 41 and the holding device 43, respectively. . Then, after setting the first motor housing 20 a on the base 41, when setting the centering jig 44 on the upper end of the rotary shaft 13, the flange 44 a of the centering jig 44 and the upper end of the rotary shaft 13 are set. The centering jig 44 is set with the spring member 45 interposed between the second bearing 22 and the second bearing 22. Thereby, the outer ring 31 of the second bearing 22 is held by the spring member 45 in the arrangement step and the cooling step.

According to the above, the following effects can be obtained in the first reference example .
Since the outer ring 31 of the second bearing 22 is held by the spring member 45, the inclination of the outer ring 31 can be reliably suppressed.
Further, since the end surface of the outer ring 31 of the second bearing 22 and the end surface of the inner ring 30 are maintained substantially parallel by the spring member 45, the clearance between the outer ring 31 and the rolling element 32 in the axial direction, the inner ring 30 and the rolling element 32, The gap in the axial direction is always kept constant. That is, since the degree of close contact in the axial direction between the outer ring 31 or the inner ring 30 and the rolling element 32 is neither too large nor too small, an effect that the friction torque can be made constant can be obtained.

In the first reference example , the spring member 45 is used as the holding means. However, the present invention is not limited to this, and for example, a cylindrical collar (rigid body) or a cylindrical rubber having substantially the same diameter as the outer ring 31 is used. It may be a member.

[ Second Embodiment]
Below, the manufacturing method of the electric motor which concerns on the 2nd Embodiment of this invention is demonstrated. Since this embodiment is a modification of the manufacturing apparatus and manufacturing method of the electric motor according to the first embodiment, the same components as those of the electric motor according to the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. Omitted. In the drawings to be referred to, FIG. 5 is a diagram showing a method of manufacturing the electric motor according to the second embodiment, and is a schematic sectional view showing a process of setting the first motor housing and the second motor housing in the electric motor manufacturing apparatus. (A) and schematic sectional drawing (b) which shows the process of press-fitting a rotating shaft to a 2nd bearing.

As shown in FIG. 5A, in the electric motor manufacturing apparatus 50 according to the second embodiment, the larger opening of the second motor housing 20b in which the second bearing 22 is pre-assembled is directed upward. And a holding base 52 that holds the first motor housing 20a to which the rotary shaft 13 is attached via the first bearing 21 so as to be movable up and down. Yes. An engagement hole 51a is formed at the bottom of the base 51 so that a centering jig 53 for centering the rotary shaft 13 is slidably engaged with the base 51, and surrounds the engagement hole 51a. A cylindrical collar member (holding means) 54 is provided so as to be fitted on the centering jig 53 described above. The second motor housing 20b is fixed to the base 51 so that the second bearing 22 is separated from the bottom of the base 51 by a predetermined distance. By disposing the collar member 54 in a predetermined gap between the bottom of the base 51, the collar member 54 supports the inner ring 30 of the second bearing 22, and the end surface of the inner ring 30 and the end surface of the outer ring 31 are connected. It is designed to be approximately parallel.

  The holding device 52 includes a fixing base 52a to which the flange portion 20c of the first motor housing 20a is fixed by the bolt B, and engages with the upper end of the rotating shaft 13 to press the rotating shaft 13 downward and secondly. A pressing base 52b for press-fitting into the second bearing 22 of the motor housing 20b is provided. The holding device 52 is lowered in synchronism with the retreating (lowering) of the centering jig 53 described above, so that the rotation shaft 13 is moved in the first position without the shaft center of the rotation shaft 13 being shaken. The two bearings 22 are press-fitted into the inner ring 30.

Next, a method for manufacturing the electric motor 7 according to the second embodiment will be described.
Before setting the components of the electric motor 7 in the electric motor manufacturing apparatus 50 shown in FIG. 5A, the stator 24 is assembled to the second motor housing 20b in advance (stator assembly step), and the rotor 23 is assembled. The first bearing 21 is assembled to one end (upper end in the figure) of the rotating shaft 13 (rotating shaft side bearing assembling step), and the first bearing 21 is assembled to the first motor housing 20a. Further, the second bearing 22 is assembled in advance to the bearing mounting portion 20e of the second motor housing 20b (housing side bearing assembling step).

  Then, the second motor housing 20 b is attached to the inside of the base 51 set with the collar member 54 fitted on the centering jig 53, and the first motor housing 20 a is attached to the holding device 52. Here, when the second motor housing 20b is mounted inside the base 51 set as described above, the inner ring 30 of the second bearing 22 assembled to the second motor housing 20b is not inclined by the collar member 54. Is supposed to be retained. Thereafter, by lowering the holding device 52, the rotary shaft 13 is press-fitted into the inner ring 30 supported by the collar member 54 (press-fitting step), as shown in FIG. The manufacture of the electric motor 7 is completed by fitting the housing 20a and the second motor housing 20b.

According to the above, the following effects can be obtained in the second embodiment.
Since the inner ring 30 of the second bearing 22 is held so as not to be tilted by the collar member 54, the inner ring 30 of the second bearing 22 can be prevented from tilting in contact with the end of the rotating shaft 13 when the bearing is inserted. In addition, by suppressing the inclination of the inner ring 30 of the second bearing 22 in this way, the productivity of the electric motor 7 is improved, the quietness is excellent, the steering wheel returns well, and there is no torque fluctuation. An electric power steering apparatus 1 having a steering feeling can be provided.

Further, in the second embodiment, a heating furnace or the like (for example, a cooling device is included in the case of forced cooling) that is necessary in the first embodiment is not required, so that production facilities can be simplified. Became possible.

[ Third Embodiment]
Below, the manufacturing method of the electric motor which concerns on the 3rd Embodiment of this invention is demonstrated. Since this embodiment is a modification of the method of manufacturing the electric motor according to the first embodiment, the same components as those of the electric motor according to the first embodiment are denoted by the same reference numerals, and description thereof is omitted. In the drawings to be referred to, FIG. 6 is a view showing a method of manufacturing the electric motor according to the third embodiment, and a bearing mounting portion formed with a diameter larger than that of the second bearing is arranged around the second bearing. It is the schematic sectional drawing (a) which shows a process, and the schematic sectional drawing (b) which shows the process of caulking a bearing attaching part.

As shown in FIG. 6A, the electric motor 7 ′ according to the third embodiment includes a second motor housing 20b ′ having a slightly different structure from that of the first embodiment. The second motor housing 20b ′ has a bearing mounting portion 20e ′ whose inner surface is formed with a larger diameter than the outer surface of the second bearing 22, and the substantially bottomed cylindrical bearing mounting portion 20e. It has a structure different from that of the first embodiment in that the escape hole 20f (see FIG. 2) is not formed in the bottom of '.

Next, a method for manufacturing the electric motor 7 ′ according to the third embodiment will be described.
First, similarly to the first embodiment, the stator assembling step and the bearing assembling step are performed in advance, and the first bearing 21 assembled to the rotating shaft 13 is assembled to the first motor housing 20a. Then, as shown in FIG. 6A, the first motor housing 20a and the second motor housing 20b ′ are assembled by an apparatus such as the electric motor manufacturing apparatus 40 (see FIG. 3) of the first embodiment. At this time, since the bearing mounting portion 20e ′ of the second motor housing 20b ′ is formed larger than the outer surface of the second bearing 22, they are arranged via a predetermined gap in the radial direction. (Arrangement process). Thereafter, as shown in FIG. 6B, the second bearing 22 is fixed to the bearing mounting portion 20e ′ by caulking the bearing mounting portion 20e ′ in the radial direction, that is, plastically deforming (plastic deformation step). .

According to the above, the following effects can be obtained in the third embodiment.
Since the second bearing 22 is inserted into the bearing mounting portion 20e ′ with a predetermined gap between the bearing mounting portion 20e ′ of the second motor housing 20b and the second bearing 22, the second bearing 22 is inserted when the bearing is inserted. It is possible to prevent the outer ring 31 from tilting in contact with the bearing mounting portion 20e ′. In addition, by suppressing the inclination of the outer ring 31 of the second bearing 22 in this manner, the productivity of the electric motor 7 ′ is improved, the silence is excellent, the steering wheel returns well, and there is no torque fluctuation. It is possible to provide the electric power steering apparatus 1 having a steering feeling.

In addition, since there is a gap between the bearing mounting portion 20e ′ and the second bearing 22 before the bearing mounting portion 20e ′ is crimped, the alignment work (rotation) after the assembly of the motor housings 20a and 20b ′ is performed. There is also a merit that it becomes easier to check whether the rotating shaft 13 rotates smoothly by gripping the end portion of the shaft 13 on the first bearing 21 side and rotating the rotating shaft 13.
Furthermore, in the third embodiment, since the clearance hole 20f for preventing interference with the centering jig 44 as in the first embodiment is not formed in the bottom of the bearing mounting portion 20e ′, It is not necessary to prepare a separate lid for closing the escape hole 20f, and the electric power steering apparatus 1 can be manufactured at a lower cost.

[ Second Reference Example ]
Below, the manufacturing method of the electric motor which concerns on the 2nd reference example of this invention is demonstrated. Since this embodiment is a modification of the method of manufacturing the electric motor according to the third embodiment, the same components as those of the electric motor according to the third embodiment are denoted by the same reference numerals, and the description thereof is omitted. In the drawings to be referred to, FIG. 7 is a schematic cross-sectional view showing a method for manufacturing an electric motor according to a second reference example .

As shown in FIG. 7, the electric motor 7 ′ according to the second reference example has substantially the same structure as the electric motor 7 ′ according to the third embodiment before caulking.
Next, a method for manufacturing the electric motor 7 ′ according to the second reference example will be described.
Similarly to the third embodiment, the stator assembly process and the bearing assembly process are performed in advance, and the first bearing 21 assembled to the rotating shaft 13 is assembled to the first motor housing 20a. And after apply | coating the adhesive agent G to the outer peripheral surface of the outer ring | wheel 31 of the 2nd bearing 22 (application | coating process), the outer ring | wheel 31 and 2nd of the 2nd bearing 22 are combined by combining each motor housing 20a, 20b (arrangement process). The bearing mounting portion 20e ′ of the motor housing 20b ′ is coupled to the adhesive G by solidification. Even if the outer ring 31 of the second bearing 22 is inclined due to the influence of the adhesive G in the arranging step, the rotating shaft 13 can be easily aligned before the adhesive G is solidified. Therefore, the inclination of the outer ring 31 is suppressed.

According to the above, the following effects can be obtained in the second reference example .
By simply placing the bearing mounting portion 20e ′ of the second motor housing 20b ′ with respect to the second bearing 22 coated with the adhesive G and performing an appropriate alignment operation, the inclination of the outer ring 31 of the second bearing 22 can be easily performed. Can be suppressed. In addition, by suppressing the inclination of the outer ring 31 of the second bearing 22 in this manner, the productivity of the electric motor 7 ′ is improved, the silence is excellent, the steering wheel returns well, and there is no torque fluctuation. It is possible to provide the electric power steering apparatus 1 having a steering feeling.

Further, since the solidified adhesive G has a larger load-displacement hysteresis than metal, it has good vibration absorption. Therefore, it is possible to further reduce the vibration of the electric motor 7 ′. Further, since the escape hole 20f is not formed as in the third embodiment, it is not necessary to separately prepare a lid for closing the escape hole 20f, and the electric power steering apparatus 1 can be manufactured at a lower cost.

In the second reference example , the adhesive G is applied only to the outer ring 31 of the second bearing 22. However, the present invention is not limited to this, and only the bearing mounting portion 20e 'or the outer ring of the second bearing 22 is applied. The adhesive G may be applied to both 31 and the bearing mounting portion 20e ′.

In the second reference example , the adhesive G is applied before the arrangement step. However, the present invention is not limited to this, and the second bearing is formed from a hole formed in the second motor housing 20b ′ after the arrangement step. You may apply | coat so that the adhesive agent G may be poured between 22 outer ring | wheels 31 and bearing attaching part 20e '. When the coating process is performed before the arrangement process as in the second reference example , the first reference shown in FIG. 4 is used so that the outer ring 31 of the second bearing 22 does not tilt due to the viscosity of the adhesive G. You may hold | maintain the outer ring | wheel 31 of the 2nd bearing 22 suitably by the holding means (spring member 45 grade | etc.,) Like an example . However, in this case, it is necessary to appropriately provide a relief hole 20f in the bearing mounting portion 20e ′.

The present invention is not limited to the first to third embodiments, and can be implemented in various forms.
The order of the steps in each of the embodiments is not particularly limited. For example, either the stator assembly step or the bearing assembly step in the first embodiment or the like may be first.
In each of the above embodiments, only two bearings are provided, but the present invention is not limited to this, and three or more bearings may be provided.

In each of the above embodiments, the rolling bearing has been adopted in which the end surfaces of the outer ring and the inner ring are flush with each other. However, the present invention is not limited to this, and for example, the end surfaces of the outer ring and the inner ring are configured to be displaced. A bearing or the like may be employed.
The present invention may be applied to any electric motor, but the effect can be effectively utilized particularly when it is applied to an 8-pole 9-slot brushless motor. In other words, even in the case of an 8-pole 9-slot brushless motor that tends to generate a radial eccentric load with respect to the rotating shaft when the motor is driven, the present invention can be applied to improve the supporting accuracy of the rotating shaft and to generate vibration. In addition to being able to achieve suppression, fluctuations in friction torque (cogging torque) and increases in friction torque can be suppressed. Therefore, the torque fluctuation on the steering wheel is eliminated, the steering feeling is improved, and the electric power steering apparatus excellent in silence can be provided at low cost.

It is a schematic structure figure showing an electric power steering device provided with an electric motor manufactured with a manufacturing method concerning a 1st embodiment. It is a schematic sectional drawing which shows the electric motor of FIG. It is a figure which shows the manufacturing method of the electric motor which concerns on 1st Embodiment, The schematic sectional drawing (a) which shows the process of setting a 1st motor housing and a 2nd motor housing to an electric motor manufacturing apparatus, respectively, and thermally expanded It is the schematic sectional drawing (b) which shows the process of arrange | positioning the bearing attaching part of a 2nd motor housing around a 2nd bearing, and the schematic sectional drawing (c) which shows the process which cools and shrinks a bearing attaching part. It is a schematic sectional drawing which shows the manufacturing method of the electric motor which concerns on a 1st reference example . It is a figure which shows the manufacturing method of the electric motor which concerns on 2nd Embodiment, The schematic sectional drawing (a) which shows the process of setting a 1st motor housing and a 2nd motor housing in an electric motor manufacturing apparatus, and a 2nd bearing It is a schematic sectional drawing (b) which shows the process of press-fitting a rotating shaft. It is a figure which shows the manufacturing method of the electric motor which concerns on 3rd Embodiment, and is schematic sectional drawing (a) which shows the process of arrange | positioning the bearing attachment part formed in the diameter larger than a 2nd bearing around the 2nd bearing It is a schematic sectional drawing (b) which shows the process of crimping a bearing attaching part. It is a schematic sectional drawing which shows the manufacturing method of the electric motor which concerns on a 2nd reference example . It is a principal part expanded sectional view which shows the state in which the outer ring | wheel inclined with respect to the inner ring | wheel of a bearing.

DESCRIPTION OF SYMBOLS 1 Electric power steering apparatus 7, 7 'Electric motor 13 Rotating shaft 20a 1st motor housing 20b, 20b' 2nd motor housing 20d Bearing mounting part 20e, 20e 'Bearing mounting part 21 1st bearing (rolling bearing)
22 Second bearing (rolling bearing)
23 Rotor 24 Stator 27 Inner ring 28 Outer ring 29 Rolling body 30 Inner ring 31 Outer ring 32 Rolling body 40, 40 ', 50 Electric motor manufacturing apparatus 44a Hook 45 Spring member (holding means)
54 Color member (holding means)
G adhesive

Claims (5)

A rotor having a rotating shaft, a first bearing and a second bearing for supporting both ends of the rotating shaft, a first housing to which the rotating shaft is attached via the first bearing, and a stator are fixed. A method of manufacturing an electric motor having a second housing and a bearing mounting portion for mounting a second bearing to the second housing,
A stator assembling step of assembling the stator to the second housing;
A bearing assembling step for assembling the first bearing and the second bearing to the rotary shaft;
Assembling the first bearing into the first housing by press-fitting , and thereafter
A heating step of heating at least the bearing mounting portion of the second housing to expand in the radial direction is performed, and then the bearing mounting portion expanded and the second bearing held using holding means An arrangement step of arranging through a predetermined gap in the radial direction is performed, and then a cooling step of fixing the second bearing to the bearing mounting portion by contracting by cooling at least the bearing mounting portion. A method for manufacturing an electric motor characterized by the above.   The method of manufacturing an electric motor according to claim 1, wherein the heating step heats the entire second housing.   The method of manufacturing an electric motor according to claim 1, wherein the second housing is formed of a single member. A rotor having a rotating shaft, a first bearing and a second bearing for supporting both ends of the rotating shaft, a first housing to which the rotating shaft is attached via the first bearing, and a stator are fixed. A method of manufacturing an electric motor having a second housing and a bearing mounting portion for mounting a second bearing to the second housing,
A stator assembling step of assembling the stator to the second housing;
A rotary shaft side bearing assembly step of assembling the first bearing to one end of the rotary shaft;
A second housing side bearing assembly step of assembling the second bearing to the second housing;
The outer peripheral portion of the second housing to which the second bearing is assembled is held by the first holding means, and the inner ring of the second bearing assembled to the second housing is held by the second holding means , And a press-fitting step of press-fitting the other end of the rotary shaft into the inner ring of the second bearing in a held state. A rotor having a rotating shaft, a first bearing and a second bearing for supporting both ends of the rotating shaft, a first housing to which the rotating shaft is attached via the first bearing, and a stator are fixed. A method of manufacturing an electric motor having a second housing and a bearing mounting portion for mounting a second bearing to the second housing,
A stator assembling step of assembling the stator to the second housing;
A bearing assembling step for assembling the first bearing and the second bearing to the rotary shaft;
An arrangement step of arranging the bearing mounting portion and the second bearing in a radial direction with a predetermined gap therebetween;
A plastic deformation step of fixing only the second bearing to the bearing mounting portion by plastically deforming the bearing mounting portion in a radial direction so as to be in contact with the entire outer periphery of the outer ring of the second bearing. A method for manufacturing an electric motor.

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