JP2014079054A - Motor and method for manufacturing motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor that improves ease of assembly.SOLUTION: A motor 10 includes: a first frame 11, and a second frame 12, that are mounted to two respective axial sides of a stator 13 and that sandwich the stator 13 axially therebetween; and a first ball bearing B1, and a second ball bearing B2, that are provided in respective bearing housings 25 and 31 of the first frame 11 and the second frame 12. The bearing housing 31 of the second frame 12 is configured so as to allow the second ball bearing B2 to be mounted from a side of the stator 13 in a direction of a rotation axis.

Description

  The present invention relates to a motor and a method for manufacturing the motor.

  Conventionally, as shown in Patent Document 1, for example, there is a motor including a first end frame and a second end frame that are assembled on both sides in the axial direction of the stator and sandwich the stator in the axial direction. The first and second end frames are formed with bearing housing portions that are recessed from the respective outer end surfaces in the axial direction (end surfaces on the side opposite to the stator) to the inside of the motor, and ball bearings are housed in the respective bearing housing portions. . And the rotor arrange | positioned at the inner peripheral side of the stator core is being fixed to the rotating shaft pivotally supported by each ball bearing so that integral rotation is possible.

JP 2011-239533 A

  In the assembly of the motor as described in Patent Document 1, the stator and the second end frame are assembled after the rotary shaft is press-fitted and fixed to the ball bearing accommodated and fixed in the bearing accommodating portion of the first end frame. Thereafter, a ball bearing is fitted between the bearing housing portion of the second end frame and the rotating shaft inserted through the bearing housing portion. At this time, it is difficult to assemble the ball bearing on the second end frame side because the ball bearing must be externally fitted to the rotating shaft and at the same time, the ball bearing must be internally fitted to the bearing housing portion.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor and a method of manufacturing the motor that can improve the assembling property.

  A motor that solves the above problems includes a stator having a cylindrical stator core, first and second end frames that are assembled on both sides of the stator in the axial direction and sandwich the stator in the axial direction, and the first A first ball bearing provided in the bearing housing portion of the end frame, a second ball bearing provided in the bearing housing portion of the second end frame, and a rotation shaft rotatably supported by each ball bearing; A motor including a rotor fixed to the rotary shaft so as to be integrally rotatable at an inner peripheral side position of the stator core, wherein the bearing housing portion of the second end frame moves the second ball bearing in the direction of the rotary shaft. It can be assembled from the stator side.

  According to this configuration, in the state where the first ball bearing housed and fixed in the bearing housing portion of the first end frame and the second ball bearing whose outer peripheral side is not fixed are fixed to the rotating shaft, the second ball bearing On the other hand, it is possible to externally fix and fix the bearing accommodating portion of the second end frame. As a result, it is not necessary to fix the second ball bearing to the rotating shaft and the second end frame to the bearing housing at the same time, so that the second ball bearing can be easily assembled. Can be improved.

  Furthermore, the bearing housing portion of the second end frame passes through the second end frame in the axial direction, and includes a housing hole in which the second ball bearing is fixed, and a non-stator side end portion of the housing hole. And an adjusting member that adjusts an axial clearance between the second ball bearing and the second ball bearing. The adjusting member and the second ball bearing are arranged in an axial direction with respect to the second ball bearing. An urging member for applying an urging force to the stator side is interposed.

  According to this configuration, by adjusting the fixing position of the adjustment member, the axial clearance between the adjustment member and the second ball bearing is constant even if the fixing position of the second ball bearing in the accommodation hole varies. It becomes possible. Thereby, it becomes possible to stabilize the urging force of the urging member with respect to the second ball bearing.

Furthermore, the stator core is formed by laminating plate-shaped core sheets along the axial direction of the rotation shaft.
According to this configuration, the dimensional tolerance in the rotation axis direction (core sheet stacking direction) is larger than that in the configuration in which the stator core is integrally formed by casting or the like. As a result, the variation in the interval between the end frames (that is, the fixed position in the accommodation hole of the second ball bearing) becomes more prominent, so the biasing force of the biasing member is stabilized by adjusting the position of the adjustment member. The effect is more remarkable.

  Further, the adjustment member has an abutting portion capable of abutting in the axial direction with respect to the second end frame, and the abutting portion and the second end frame contact the second end frame. Movement to the 2-ball bearing side is restricted.

  According to this configuration, the urging member can be prevented from being crushed by the second ball bearing and the adjusting member, and as a result, the urging member can be prevented from being damaged.

  A method of manufacturing a motor that solves the above problems includes a stator having a cylindrical stator core, a first end frame and a second end frame that are assembled on both sides of the stator in the axial direction and sandwich the stator in the axial direction, A first ball bearing provided in a bearing accommodating portion of the first end frame; a second ball bearing provided in a bearing accommodating portion of the second end frame; and a rotation supported rotatably on each of the ball bearings. A manufacturing method for manufacturing a motor including a shaft and a rotor fixed to the rotary shaft so as to be integrally rotatable at an inner peripheral side position of the stator core, wherein the motor is housed and fixed in a bearing housing portion of the first end frame. The first ball bearing and the second ball bearing whose outer peripheral side is not fixed are attached to the rotating shaft. The second end frame is sandwiched between the first end frame and the stator core is sandwiched between the second end frame and the second ball bearing. Assemble.

  According to this configuration, since it is not necessary to simultaneously fix the second ball bearing to the rotating shaft and the second end frame to the bearing accommodating portion, the second ball bearing can be easily assembled. The assembly property of the motor can be improved.

  Further, the first end frame to which the first ball bearing is fixed is used as a reference member, and the rotation shaft, the second ball bearing, the stator, and the second end frame are the same with respect to the first end frame. Assemble in the direction.

  According to this method, since the manufacturing process can be simplified, the assembling property of the motor can be further improved.

  According to the motor of the present invention, the assemblability can be improved.

It is sectional drawing which shows schematic structure of the motor of embodiment. It is a schematic diagram which shows the assembly | attachment aspect of the motor of the same form. It is sectional drawing which expands and shows a part of motor of another example. It is sectional drawing which expands and shows a part of motor of another example.

Hereinafter, an embodiment of a motor and a method for manufacturing the motor will be described with reference to the drawings.
As shown in FIG. 1, the motor 10 includes a first end frame 11 and a second end frame 12 (hereinafter simply referred to as the first frame 11 and the second frame 12). It is sandwiched and configured. The first and second frames 11 and 12 are provided with first and second ball bearings B1 and B2, respectively, so as to be coaxial with each other, and are supported by the first and second ball bearings B1 and B2. A rotor 15 is fixed to the shaft 14 so as to be integrally rotatable at an inner peripheral side position of the stator 13. The frame that holds the axial output side (lower side in FIG. 1) of the motor 10 is the first frame 11, and the frame that holds the axially opposite output side is the second frame 12. The frames 11 and 12 are fastened and fixed by through bolts 16 at positions on the outer peripheral side of the stator 13 so as not to be separated from each other.

  The stator 13 includes an annular stator core 17 and a coil 18 wound around the stator core 17. The stator core 17 is formed by laminating a plurality of core sheets 17a formed by stamping a steel plate by press working in the axial direction and integrating them by caulking.

  Each frame 11 and 12 is formed with metal materials, such as aluminum and steel. Each of the frames 11 and 12 includes a substantially disc-shaped main body portion 21 and a cylindrical stator holding portion 22 that extends from the main body portion 21 along the axial direction of the rotary shaft 14.

  The tip end portion (the axially inner end portion) of the stator holding portion 22 is externally fitted to both axial end portions of the stator core 17. Each stator holding portion 22 is formed with a contact surface 23 that contacts the stator core 17 in the axial direction of the rotary shaft 14.

  A plurality of bolt fastening portions 24 (only two are shown in FIG. 1) extending outward from the outer shape of the stator 13 are extended and formed on the main body portion 21 of each frame 11, 12. The parts 24 are connected and fixed to each other by through bolts 16. Thereby, each frame 11 and 12 is fixed in a state where the stator 13 is sandwiched by the stator holding portion 22.

  A first bearing accommodating portion 25 that accommodates the first ball bearing B <b> 1 is formed in the central portion of the main body portion 21 of the first frame 11. The first bearing housing portion 25 has a shape that is recessed from the axially outer end surface of the first frame 11 toward the motor inner side (stator 13 side). That is, the 1st bearing accommodating part 25 is comprised so that the 1st ball bearing B1 can be assembled | attached from the motor outer side (counter stator side), and cannot be assembled | attached from the motor inner side.

  A positioning bottom portion 26 that abuts the first ball bearing B1 in the axial direction is formed at an end portion of the first bearing housing portion 25 on the motor inner side, and the rotating shaft 14 is inserted into the positioning bottom portion 26. An insertion hole 27 is formed. The positioning bottom portion 26 is in contact with the first ball bearing B1 in the axial direction, thereby determining the position of the first ball bearing B1 in the axial direction.

  A second bearing housing portion 31 is formed at the central portion of the main body portion 21 of the second frame 12 so that the second ball bearing B2 can be assembled from the stator 13 side (motor internal side) in the rotation axis direction. Yes. The second bearing accommodating portion 31 closes the circular accommodating hole 32 penetrating the main body portion 21 of the second frame 12 in the rotation axis direction, and the motor outer side end (anti-stator side end) of the accommodating hole 32. The adjustment member 33 includes a wave washer 34 (biasing member) interposed between the second ball bearing B2 accommodated in the accommodation hole 32 and the adjustment member 33.

  A fixed recess 35 having a circular shape larger in diameter than the accommodation hole 32 is formed at the end of the accommodation hole 32 on the motor outer side, and the accommodation hole 32 and the fixed recess 35 are formed so as to be connected via a stepped portion 36. Yes.

  The adjustment member 33 includes a washer pressing portion 37 that is inserted into the accommodation hole 32 and contacts the wave washer 34 in the rotation axis direction, and a press-fit portion 38 that is press-fitted and fixed in the fixed recess 35. The washer pressing portion 37 and the press-fitting portion 38 have a circular shape that is coaxial with each other, and the outer diameter of the press-fitting portion 38 is formed larger than the outer diameter of the washer pressing portion 37. A through hole 39 is formed in the center of the adjustment member 33 so as to penetrate the washer pressing portion 37 and the press-fit portion 38 in the rotation axis direction. The fixing position of the press-fitting portion 38 of the adjustment member 33 can be adjusted in the axial direction of the rotary shaft 14.

  The rotating shaft 14 includes a cylindrical core fixing portion 42 to which a rotor core 41 constituting the rotor 15 is fixed, and cylindrical supported portions 43 and 44 respectively extending from both axial sides of the core fixing portion 42. Is formed. The core fixing portion 42 and the supported shaft portions 43 and 44 are coaxial with each other, and the outer diameters of the supported shaft portions 43 and 44 are smaller than the outer diameter of the core fixing portion 42.

  The rotor core 41 has a cylindrical shape and is externally fixed to the core fixing portion 42 of the rotating shaft 14. A plurality of magnets 45 constituting magnetic poles are fixed to the outer peripheral surface of the rotor core 41, and each magnet 45 faces the inner peripheral surface of the stator core 17 in the radial direction.

  The pivot shafts 43 and 44 are pivotally supported by the first and second ball bearings B1 and B2, respectively. The pivoted support portion 43 on the first frame 11 side is inserted into the insertion hole 27 of the first bearing housing portion 25 and protrudes from the first ball bearing B1 to the outside of the motor. The protruding portion includes an output portion. A joint (not shown) is attached.

  The supported portion 44 that is pivotally supported by the second ball bearing B <b> 2 is inserted through the wave washer 34 and the through hole 39 of the adjustment member 33. The second ball bearing B <b> 2 is in contact with the stepped portion 46 between the pivoted support portion 44 and the core fixing portion 42 in the axial direction. Further, the wave washer 34 applies a pressure toward the axial stator 13 to the second ball bearing B2 in order to suppress the shakiness of the rotating shaft 14 and the rotor 15 in the axial direction.

Next, the manufacturing method of the motor 10 of this embodiment is demonstrated.
As shown in FIG. 2, in the assembly method of this embodiment, the first frame 11 is used as a reference member for assembly, and other components are assembled in the same direction (downward in FIG. 2).

First, the first frame 11 in a state where the first ball bearing B1 is press-fitted and fixed in the first bearing housing portion 25 is installed on the work table S so as not to move.
Next, the supported portion 43 of the rotating shaft 14 with the rotor core 41 fixed to the core fixing portion 42 and the second ball bearing B2 press-fitted to the supported shaft portion 44 is press-fitted and fixed to the first ball bearing B1. . The second ball bearing B2 is fixed so as to contact the stepped portion 46 of the rotating shaft 14 in the axial direction.

Next, the stator core 17 is fitted into the distal end portion of the stator holding portion 22 of the first frame 11.
Next, the front end portion of the stator holding portion 22 of the second frame 12 is externally fitted to the stator core 17 assembled to the stator holding portion 22 of the first frame 11. At this time, the second ball bearing B2 fixed to the pivoted support portion 44 of the rotating shaft 14 is fitted into the accommodation hole 32 of the second frame 12 with a gap, and is in axial contact with the stepped portion 46 in the axial direction. It is prevented from shifting inward.

  Here, due to variations (tolerances) in the axial dimension of the stator core 17, the axial distance between the first and second frames 11 and 12 assembled on both axial sides of the stator core 17 (that is, the first frame 11 relative to the first frame 11). The axial position of the two frames 12 varies. Thereby, the axial position of the second frame 12 with respect to the second ball bearing B2 fixed to the rotating shaft 14 varies. Here, in this embodiment, since the second ball bearing B2 is not positioned with respect to the accommodation hole 32 of the second frame 12, the fixing position of the second ball bearing B2 within the accommodation hole 32 is the position of the second frame 12. It changes according to the variation of the axial position. That is, the accommodation hole 32 serves to absorb variations in the axial position of the second frame 12. The axial length of the accommodation hole 32 is set to a dimension that takes into account the tolerance of the stator core 17.

  Next, the bolt fastening portions 24 of the first and second frames 11 and 12 are fastened and fixed by the through bolts 16. Accordingly, the second frame 12 is fixed so as not to be separated from the first frame 11 in the axial direction.

  Next, the wave washer 34 is accommodated in the accommodation hole 32 of the second frame 12, and the wave washer 34 is brought into contact with the second ball bearing B2 in the axial direction. Thereafter, the washer pressing portion 37 of the adjustment member 33 is inserted into the accommodation hole 32, and the press-fitting portion 38 of the adjustment member 33 is press-fitted and fixed to the fixing recess 35 of the second frame 12. Thereby, the wave washer 34 is interposed between the washer pressing portion 37 of the adjustment member 33 and the second ball bearing B2.

  Here, the urging force that the wave washer 34 applies to the second ball bearing B2 is determined by the distance (axial gap) between the washer pressing portion 37 of the adjustment member 33 and the second ball bearing B2. As described above, the fixing position of the second ball bearing B2 in the accommodation hole 32 varies depending on the axial position of the second frame 12, but the press-fitting portion 38 of one of the adjustment members 33 is located in the fixing recess 35. On the other hand, it can be fixed at an arbitrary position. For this reason, by adjusting the fixing position of the adjusting member 33 according to the fixing position of the second ball bearing B2, the urging force of the wave washer 34 against the second ball bearing B2 is independent of the fixing position of the second ball bearing B2. It can be made constant.

Next, the operation of this embodiment will be described.
The housing hole 32 (second bearing housing portion 31) of the second frame 12 is configured such that the second ball bearing B2 can be assembled from the motor inner side (axial stator 13 side). Therefore, it is possible to externally fix the receiving hole 32 of the second frame 12 to the second ball bearing B2 in a state where the first and second ball bearings B1 and B2 are fixed to the rotating shaft 14. It has become. As a result, it is not necessary to fix the second ball bearing B2 to the rotating shaft 14 and to the accommodation hole 32 at the same time, so that the assembly of the motor 10 is improved.

  In addition, since the stator core 17 of the present embodiment has a laminated structure of the core sheets 17a, the dimensional tolerance in the axial direction of the rotating shaft 14 (stacking direction of the core sheets 17a) is larger than a configuration in which the stator core is integrally formed by casting or the like. large. Thereby, since the dispersion | variation in the axial direction position of the 2nd frame 12 becomes more remarkable, the effect which stabilizes the urging | biasing force of the wave washer 34 by position adjustment of the adjustment member 33 will be exhibited more notably.

Next, characteristic effects of the present embodiment will be described.
(1) The 2nd bearing accommodating part 31 of the 2nd flame | frame 12 is comprised so that the 2nd ball bearing B2 can be assembled | attached from the stator 13 side (motor inner side) of a rotating shaft direction. According to this configuration, in the state where the first ball bearing B1 fixed to the first frame 11 and the second ball bearing B2 whose outer peripheral side is not fixed are assembled to the rotary shaft 14, the second ball 12 The two-bearing accommodating portion 31 can be externally fitted and fixed to the second ball bearing B2. This eliminates the need for simultaneously fixing the second ball bearing B2 to the rotating shaft 14 and fixing the second ball bearing housing 31 to each other, so that the second ball bearing B2 can be easily assembled. Assembling property can be improved.

  (2) The second bearing housing portion 31 penetrates the main body portion 21 of the second frame 12 in the axial direction, the housing hole 32 in which the second ball bearing B2 is fixed, and the side opposite to the stator of the housing hole 32 And an adjusting member 33 that adjusts the axial clearance between the second ball bearing B2 and the second ball bearing B2. And between the adjustment member 33 and the 2nd ball bearing B2, the wave washer 34 which provides the urging | biasing force to the stator 13 side of the axial direction with respect to the 2nd ball bearing B2 is interposed.

  According to this configuration, by adjusting the fixing position of the adjusting member 33, the distance between the adjusting member 33 and the second ball bearing B2 is constant even if the fixing position of the second ball bearing B2 in the accommodation hole 32 varies. It becomes possible. Thereby, it is possible to stabilize the urging force of the wave washer 34 against the second ball bearing B2.

  (3) Since the stator core 17 is formed by laminating the plate-like core sheets 17a along the axial direction of the rotating shaft 14, the stator core 17 has a rotating shaft direction (core) compared to a configuration in which the stator core 17 is integrally formed by casting or the like. The dimensional tolerance in the sheet 17a stacking direction) is large. As a result, the variation in the distance between the frames 11 and 12 (that is, the fixed position of the second ball bearing B2 in the accommodation hole 32) becomes more prominent. Therefore, the position of the wave washer 34 is adjusted by adjusting the position of the adjustment member 33. The effect of stabilizing the urging force is more remarkable.

  (4) The adjustment member 33 has a press-fit portion 38 (contact portion) that can contact the stepped portion 36 of the second frame 12 in the axial direction, and the press-fit portion 38 and the stepped portion 36 are in contact with each other. The movement of the adjustment member 33 toward the second ball bearing B2 is restricted. According to this configuration, the wave washer 34 can be prevented from being crushed by the second ball bearing B2 and the adjustment member 33, and as a result, the wave washer 34 can be prevented from being damaged.

  (5) The first frame 11 to which the first ball bearing B1 is fixed is used as a reference member, and the rotating shaft 14, the second ball bearing B2, the stator 13, and the second frame 12 are in the same direction with respect to the first frame 11. Assemble to. According to this structure, since a manufacturing process can be simplified, the assembly | attachment property of the motor 10 can be improved more.

In addition, you may change the said embodiment as follows.
In the above embodiment, the step portion 36 is formed between the accommodation hole 32 of the second bearing housing portion 31 and the fixed recess 35, and the press-fitting portion 38 of the adjustment member 33 contacts the step portion 36 in the axial direction. Although it was set as the structure which can be contacted, it is not specifically limited to this. For example, as shown in FIG. 3, the fixing recess 35 and the stepped portion 36 may be omitted from the above-described embodiment, and the accommodation hole 32 may be formed to penetrate to the end portion outside the motor with a constant diameter.

  In the above embodiment, the second bearing housing portion 31 includes the adjustment member 33 (washer pressing portion 37) that is a separate member from the second frame 12, but is not particularly limited thereto. For example, as shown in FIG. 4, a washer pressing portion 32a is integrally formed at the motor outer end of the accommodation hole 32, and a wave washer 34 is interposed between the washer pressing portion 32a and the second ball bearing B2 in the axial direction. It is good also as a structure. Even with such a configuration, the assembling property of the motor can be improved as in the above embodiment.

  In the above embodiment, the adjustment member 33 is press-fitted and fixed to the fixing recess 35 of the second frame 12. However, for example, the adjustment member 33 is screwed into the accommodation hole 32 or the fixing recess 35. It is good also as a structure. Further, for example, after the adjustment member 33 is fitted into the accommodation hole 32 or the fixed recess 35 with a gap, a part of the peripheral wall of the accommodation hole 32 or the fixed recess 35 is caulked to form a locking claw that protrudes toward the inner diameter side. The movement of the adjustment member 33 to the outside of the motor may be prevented. By such screw screwing and caulking, it is possible to fix the adjusting member 33 at an arbitrary axial position, and to adjust the axial gap between the adjusting member 33 and the second ball bearing B2. Is possible.

  In the above embodiment, the wave washer 34 is used as the urging member that applies the urging force to the second ball bearing B2. However, for example, a spring washer or the like may be used.

  In the above embodiment, the first bearing housing portion 25 that houses the first ball bearing B1 has a shape that is recessed from the axially outer end surface of the first frame 11 toward the motor inner side (stator 13 side). It is not particularly limited. For example, the first bearing housing portion 25 may be recessed from the axially inner end surface (motor inner side end surface) of the first frame 11 to the motor outer side, and the first ball bearing B1 may be assembled from the motor inner side. .

-In the rotating shaft 14 of the said embodiment, it is good also considering the core fixing | fixed part 42 and the pivoted support parts 43 and 44 as the same diameter.
In the above embodiment, the stator holding portions 22 of the frames 11 and 12 are externally fitted to the stator core 17. However, for example, the stator holding portion 22 may be internally fitted to the stator core 17. .

  DESCRIPTION OF SYMBOLS 10 ... Motor, 11 ... 1st end frame, 12 ... 2nd end frame, 13 ... Stator, 14 ... Rotating shaft, 15 ... Rotor, 17 ... Stator core, 17a ... Core sheet | seat, 25 ... 1st bearing accommodating part, 31 ... 2nd bearing accommodating part, 32 ... accommodating hole, 33 ... adjusting member, 34 ... wave washer (biasing member), 38 ... press-fitting part (contacting part), B1 ... first ball bearing, B2 ... second ball bearing.

Claims (6)

A stator having a cylindrical stator core;
A first end frame and a second end frame that are respectively assembled on both axial sides of the stator and sandwich the stator in the axial direction;
A first ball bearing provided in a bearing housing portion of the first end frame;
A second ball bearing provided in a bearing housing portion of the second end frame;
A rotating shaft rotatably supported by each of the ball bearings;
A motor including a rotor fixed to the rotary shaft so as to be integrally rotatable at an inner peripheral side position of the stator core;
The motor is characterized in that the bearing housing portion of the second end frame is configured such that the second ball bearing can be assembled from the stator side in the rotation axis direction. The motor according to claim 1,
The bearing housing portion of the second end frame penetrates the second end frame in the axial direction, and is inserted and fixed to a housing hole in which the second ball bearing is fixed and an end of the housing hole opposite to the stator. And an adjusting member for adjusting an axial clearance between the second ball bearing,
A motor characterized in that a biasing member is provided between the adjusting member and the second ball bearing to apply a biasing force to the stator side in the axial direction with respect to the second ball bearing. . The motor according to claim 2,
The stator core is formed by laminating a plate-shaped core sheet along the axial direction of the rotating shaft. The motor according to claim 2 or 3,
The adjustment member has a contact portion that can contact the second end frame in the axial direction;
The motor, wherein movement of the adjustment member toward the second ball bearing is restricted by contact between the contact portion and the second end frame. A stator having a cylindrical stator core;
A first end frame and a second end frame that are respectively assembled on both axial sides of the stator and sandwich the stator in the axial direction;
A first ball bearing provided in a bearing housing portion of the first end frame;
A second ball bearing provided in a bearing housing portion of the second end frame;
A rotating shaft rotatably supported by each of the ball bearings;
A manufacturing method for manufacturing a motor including a rotor fixed to the rotating shaft so as to be integrally rotatable at an inner peripheral side position of the stator core,
In a state where the first ball bearing housed and fixed in the bearing housing portion of the first end frame and the second ball bearing whose outer peripheral side is not fixed are assembled to the rotating shaft, A motor manufacturing method comprising assembling the second end frame so as to sandwich the stator core with the first end frame while fixing a bearing housing portion to the second ball bearing. In the manufacturing method of the motor according to claim 5,
The first end frame to which the first ball bearing is fixed is used as a reference member, and the rotating shaft, the second ball bearing, the stator, and the second end frame are arranged in the same direction with respect to the first end frame. A method of manufacturing a motor, characterized by being assembled.