JP6477313B2 - Electric motor - Google Patents

Description

  The present invention relates to an electric motor.

  The electric motor has a rotor, a stator, and a housing that houses them. The rotor is rotatably supported by the housing, and the stator is fixed to the housing. Vibration suppression is an important issue for motors. For example, Patent Document 1 discloses one of vibration suppression techniques for an electric motor. In the technique disclosed in Patent Document 1, the mass of the coil end near the cover covering the opening of the cylindrical housing is made larger than that of the coil end far from the cover. By adopting such a structure, the coil end functions as a mass damper near an opening having low rigidity in the housing, and vibration of the entire electric motor is suppressed.

JP 2006-345601 A

  By the way, from the viewpoint of assembly efficiency, there is a demand for the stator to be cantilevered to the housing at one end in the axial direction thereof. Specifically, if one end of the stator in the axial direction is fixed to the bottom of the cylindrical housing and the other end of the stator cannot be fixed, it is easy to attach a cover that covers the opening of the housing. However, it was found that when the stator is cantilevered, a torsional vibration is generated in the circumferential direction of the stator due to the interaction of the electromagnetic force between the rotor and the rotating rotor, and this torsional vibration is transmitted to the housing. . The present specification provides a technique for suppressing torsional vibration of a stator transmitted to a housing in a structure in which the stator is cantilevered.

In the electric motor disclosed in this specification, the stator is fixed to the housing via a flat intermediate ring. The stator is cantilevered by the housing via an intermediate ring arranged coaxially with the axis at one end in the axial direction. The intermediate ring includes six fastening portions provided at equal intervals in the circumferential direction of the intermediate ring and a bent portion provided at an intermediate position between adjacent fastening portions. Among these fastening portions, three fastening portions provided at intervals of 120 degrees are fastened to the stator, and the remaining three fastening portions are fastened to the housing. The bent portion is bent in the out-of-plane direction of the flat plate of the intermediate ring.

  According to such a configuration, the three fastening portions of the intermediate ring are fastened to the stator, and the remaining three fastening portions of the intermediate ring are fastened to the housing. That is, the stator is fixed to the housing via the intermediate ring, and the stator is not directly fixed to the housing. Therefore, the torsional vibration generated from the stator is not transmitted directly to the housing, but is transmitted to the housing via the intermediate ring. Here, the torsional vibration is generated in the circumferential direction of the stator. Since the intermediate ring is arranged coaxially with the axis of the stator, torsional vibration acts on the intermediate ring in the circumferential direction. According to said structure, the intermediate | middle ring is provided with the 6 fastening parts of the circumferential direction, and the bending part is provided in the intermediate position of the adjacent fastening part. This bent portion reduces the rigidity of the intermediate ring in the circumferential direction. Therefore, the torsional vibration transmitted from the stator to the intermediate ring is reduced by the intermediate ring having low circumferential rigidity and transmitted to the housing. That is, the torsional vibration of the stator transmitted to the housing can be suppressed.

  Details and further improvements of the technology disclosed in this specification will be described in the following “DETAILED DESCRIPTION”.

It is the top view seen from the axial direction of the electric motor of an example (state which removed the cover). It is sectional drawing in the II-II line of FIG. It is a top view of an intermediate ring. It is sectional drawing in the IV-IV line of FIG.

  The electric motor of the embodiment will be described with reference to the drawings. In FIG. 1, the top view of the electric motor 2 of an Example is shown. The electric motor 2 is mounted on a hybrid vehicle. The electric motor 2 includes a motor housing 20, a cylindrical stator 30, an intermediate ring 40, and a rotor 50. The motor housing 20 is provided on a part of the side surface of a transmission case mounted on the hybrid vehicle. In FIG. 1, only the part in which the motor housing 20 is provided among the side surfaces of the transmission case is shown. The stator 30 is fixed to the motor housing 20 via the intermediate ring 40. The rotor 50 is housed inside the stator 30 and is supported by the motor housing 20 so as to be rotatable about the shaft 51 of the rotor 50 as a rotation axis. The electric motor 2 also includes a housing cover that closes the opening of the motor housing 20, but the housing cover is not shown in FIG.

  The motor housing 20 includes a side wall 21 that surrounds each part (stator 30, intermediate ring 40, rotor 50, etc.) of the electric motor 2, and three fixing portions 22a-22c. The fixing portions 22 a to 22 c are portions for fixing the intermediate ring 40 to the motor housing 20. The fixing portion 22a is provided so as to protrude from the bottom surface of the motor housing 20, and the fixing portion 22a is provided with a fastening hole for fastening a bolt. The same applies to the fixing portions 22b and 22c. The fastening holes of the fixing portions 22a-22c are arranged at equal intervals at 120 ° intervals in the circumferential direction around the rotation axis of the rotor 50 (the axis of the cylindrical stator 30).

  The stator 30 is configured by winding a coil around a stator core 31 assembled in a cylindrical shape by laminating ring-shaped electromagnetic steel plates in the ring-shaped axial direction. In FIG. 1, illustration of the coil is omitted. An inner peripheral surface 34 of the cylindrical stator core 31 has a columnar shape, and a rotor 50 is accommodated inside the inner peripheral surface 34. Three bolt penetration parts 32 a-32 c are provided on the outer peripheral surface of the stator core 31. The bolt penetration portions 32 a to 32 c are ear-shaped portions that protrude outward in the radial direction of the stator 30. The three bolt penetration portions 32a to 32c are arranged at equal intervals of 120 degrees in the circumferential direction around the axis (center axis) of the cylindrical inner peripheral surface 34 of the stator 30. Each of the bolt through portions 32a-32c is provided with a through hole 33a-33c.

  The intermediate ring 40 is a flat ring. Six fastening portions 42a to 42c and 44a to 44c are provided on the outer edge of the intermediate ring 40 at equal intervals in the circumferential direction. The fastening portions 42a-42c, 44a-44c are ear-shaped portions that protrude outward in the radial direction of the intermediate ring. Of the six fastening portions, the three fastening portions 42a-42c are arranged at equal intervals at intervals of 120 degrees, and the remaining three fastening portions 44a-44c are also arranged at equal intervals at intervals of 120 degrees. . Each of the three fastening portions 42a-42c is provided with each of three through holes 43a-43c, and each of the three fastening portions 44a-44c also has three through holes 45a-45c. Each is provided. That is, the intermediate ring is provided with six through holes 43a-43c, 45a-45c at equal intervals in the circumferential direction. Of the six through holes, three through holes 43a-43c are provided at equal intervals of 120 degrees, and the remaining three through holes 45a-45c are also provided at equal intervals of 120 degrees. ing. A bent portion 46 is provided at an intermediate position between adjacent fastening portions of the intermediate ring 40. The bending part 46 is provided in each of the six intermediate positions in the adjacent fastening part.

  As shown in FIG. 1, the motor housing 20, the intermediate ring 40, and the stator 30 are assembled in this order toward the positive direction of the Z axis. Here, as shown in FIG. 1, the rotor 50 is arranged such that the axis of the shaft 51 of the rotor 50 and the axis of the cylindrical inner peripheral surface 34 of the stator 30 are coaxial. The intermediate ring 40 is arranged such that the axis of the circular center hole 47 of the intermediate ring 40 and the axis of the inner peripheral surface 34 of the stator 30 are coaxial.

  The relationship among the fixing portions 22a-22c of the motor housing 20, the fastening portions 42a-42c, 44a-44c of the intermediate ring 40, and the bolt through portions 32a-32c of the stator 30 will be described. Each of the three fastening portions 44a to 44c arranged at equal intervals in the intermediate ring 40 is fixed to each of the three fixing portions 22a to 22c arranged at equal intervals in the same manner as the motor housing 20. Specifically, a bolt passes through the through hole 45a of the fastening portion 44a of the intermediate ring 40, and the fastening portion 44a is fixed to the fixing portion 22a by fastening the bolt to a fastening hole of the fixing portion 22a of the motor housing 20. Is done. The same applies to the remaining fastening portions 44b and 44c and the fixing portions 22b and 22c. Hereinafter, the fastening portions 44a to 44c may be collectively referred to as a housing fastening portion 44. Further, the bolt through portions 32a-32c arranged at equal intervals in the stator 30 are fixed to the three fastening portions 42a-42c arranged at equal intervals in the same manner as the intermediate ring 40, respectively. Specifically, a bolt penetrates the through hole 33a of the bolt penetration part 32a of the stator 30, the bolt penetrates the through hole 43a of the fastening part 42a of the intermediate ring, and a nut is fastened to the tip of the penetrated bolt. . Thereby, the bolt penetration part 32a of the stator 30 is fixed to the fastening part 42a of the intermediate ring 40. The same applies to the remaining bolt through portions 32b and 32c and the fastening portions 42b and 42c. Hereinafter, the fastening portions 42a to 42c may be collectively referred to as the stator fastening portion 42. With this configuration, the fastening portion of the stator 30 with respect to the intermediate ring 40 and the fastening portion of the motor housing 20 with respect to the intermediate ring 40 are arranged at different positions. That is, the stator 30 is fixed to the motor housing 20 via the intermediate ring 40, and the stator 30 is not directly fixed to the motor housing 20.

  The electric motor 2 will be further described with reference to FIG. 2 is a cross-sectional view taken along line II-II in FIG. As shown in FIG. 2, the stator 30 has a motor via an intermediate ring 40 on one side in the direction of the axis CL of the stator 30 (that is, the axis of the inner peripheral surface 34). It is supported by the housing 20. The stator 30 is supported by the motor housing 20 via the intermediate ring 40 at one end on the Z axis negative direction side, and the other end on the Z axis positive direction side of the stator 30 is a free end. That is, the stator 30 is cantilevered by the housing 20. Specifically, the fastening portion 44 b of the intermediate ring 40 is fixed to the fixing portion 22 b of the motor housing 20 on the Z axis negative direction side of the stator 30 using the bolt 63. And the fastening part 42a is located on the opposite side of the fastening part 44b across the axis CL of the intermediate ring 40, and the fastening part 42a uses a bolt 61 and a nut 62 for the bolt penetration part 32a of the stator 30. 30 is fixed on the Z-axis negative direction side. In FIG. 2, other fixing portions of the motor housing 20, other bolt penetration portions of the stator 30, and other fastening portions of the intermediate ring 40 are not illustrated. Other fastening locations are also located on the Z axis negative direction side of the stator 30. Further, the coil ends 70 of the coils wound around the stator core 31 are located on both end surfaces of the stator core 31 in the axial direction.

  As shown in FIG. 2, bearings 53 and 54 are provided on both sides of the rotor core 52 in the axial direction (that is, the Z-axis direction) of the shaft 51 of the rotor 50. One bearing 53 is fitted in a bearing housing 23 provided on the bottom surface of the motor housing 20. The other bearing 54 is fitted in a bearing housing 25 provided on the housing cover 24 that covers the opening of the motor housing 20. The shaft 51 of the rotor 50 is supported by the motor housing 20 and the housing cover 24 via the bearings 53 and 54, so that the rotor 50 is rotatably supported by the motor housing 20. Note that one end of the shaft 51 in the negative Z-axis direction penetrates from the through hole provided in the bottom surface of the bearing housing 23 to the outside of the motor housing 20. As described above, the motor housing 20 is provided on a part of the side surface of the transmission case. One end of the shaft 51 in the negative Z-axis direction is connected to a gear built in the transmission. The driving force generated from the electric motor 2 is supplied to a gear built in the transmission.

  The intermediate ring 40 will be described with reference to FIG. FIG. 3 is a plan view of the intermediate ring 40. As shown in FIG. 3, the three fastening portions 42a to 42c of the intermediate ring 40 are arranged at equal intervals at intervals of 120 degrees. Similarly, the three fastening portions 44a to 44c of the intermediate ring 40 are also arranged at equal intervals at intervals of 120 degrees. The three stator fastening portions 42 and the three housing fastening portions 44 are alternately arranged one by one in the circumferential direction. A bent portion 46 is provided at an intermediate position between the adjacent fastening portions 42a and 44a. A similar bent portion 46 is also provided at an intermediate position between the adjacent fastening portions 44a and 42b. That is, each of the six bent portions 46 is provided at each of the six intermediate positions between the adjacent fastening portions. In other words, the bent portion 46 is provided between the adjacent housing fastening portion 44 and the stator fastening portion 42.

  With reference to FIG. 4, the bending part 46 of the intermediate | middle ring 40 is demonstrated. 4 is a cross-sectional view of the bent portion 46 taken along line IV-IV in FIG. The bent part 46 is a part bent in a trapezoidal shape. The bent portion 46 is provided by bending an intermediate position between adjacent fastening portions of the intermediate ring 40. All six bent portions 46 have the same shape. The bent portion 46 is provided so as to protrude in the negative Z-axis direction. That is, the bent portion 46 protrudes on the side opposite to the end surface of the stator 30 on the Z axis negative direction side. By providing the bent portion 46, the rigidity of the six intermediate positions of the intermediate ring 40 is lowered. Thereby, the rigidity of the circumferential direction of the whole intermediate ring 40 becomes low. That is, the bent portion 46 has a function of a spring that connects between the adjacent housing fastening portion 44 and the stator fastening portion 42 in the circumferential direction.

  The effect of the electric motor 2 will be described. As described above, the stator 30 of the electric motor 2 is cantilevered by the motor housing 20 at one end in the axial direction thereof. In this case, during the rotation of the rotor 50, torsional vibration is generated in the stator 30 in the circumferential direction due to the interaction of electromagnetic force between the rotor 50 and the stator 30. Here, as described above, the stator 30 is fixed to the motor housing 20 via the intermediate ring 40, and the stator 30 is not directly fixed to the motor housing 20. Therefore, the torsional vibration is not transmitted directly to the motor housing 20 but is transmitted to the motor housing 20 via the intermediate ring 40. Since the intermediate ring 40 and the stator 30 are arranged so that the axis of the center hole 47 of the intermediate ring 40 and the axis of the inner peripheral surface 34 of the stator 30 are coaxial, the intermediate ring 40 is twisted in the circumferential direction thereof. Vibration acts. As described above, the intermediate ring 40 includes six fastening portions 42a to 42c and 44a to 44c in the circumferential direction, and the bent portion 46 is provided at an intermediate position between adjacent fastening portions. The bending portion 46 reduces the circumferential rigidity of the intermediate ring 40. Therefore, the torsional vibration transmitted from the stator 30 to the intermediate ring 40 is reduced by the intermediate ring 40 having low circumferential rigidity and transmitted to the motor housing 20. That is, the torsional vibration of the stator 30 transmitted to the motor housing 20 by the intermediate ring 40 can be suppressed.

  The above-described configuration can be expressed as a system in which the stator 30 is cantilevered by the motor housing 20 via an intermediate ring 40 having a predetermined spring constant. The spring constant of the intermediate ring 40, particularly the circumferential spring constant (that is, rigidity) is designed so that the vibration transmissibility from the stator 30 to the motor housing 20 in the system is less than a desired value. In particular, the shape of the bent portion 46 of the intermediate ring 40 is designed so that the vibration transmissibility in the system is not more than a desired value. As a result of the experiment, it has been found that the frequency of torsional vibration is about 1 kHz. Vibration having a frequency of about 1 kHz tends to overlap with the resonance frequency of the housing cover 24 of the motor housing 20, and becomes a main cause of noise of the electric motor 2. The shape of the intermediate ring 40 is designed so as to obtain a desired vibration transmissibility based on the frequency of this torsional vibration. At this time, the design is made in consideration of the fastening rigidity between the stator 30 and the intermediate ring 40 and the fastening rigidity between the intermediate ring 40 and the motor housing 20. By designing the intermediate ring 40 so that the vibration transmissibility in the above system is not more than a desired value, an effect of reducing the noise of the electric motor 2 by about 10 dB is obtained compared to the case where the intermediate ring 40 is not provided. .

  Moreover, it is desired that the electric motor mounted on the hybrid vehicle is small. According to the above-described configuration, it is only necessary to add the flat intermediate ring 40 between the stator 30 and the motor housing 20. Therefore, the torsional vibration transmitted to the motor housing 20 can be suppressed without greatly changing the physique in the axial direction (that is, the Z-axis direction) of the electric motor 2.

  Points to be noted regarding the technology described in the embodiments will be described. The bent portion only needs to be provided at an intermediate position between at least one adjacent fastening portion. Moreover, the shape of the bending part 46 is not restricted to the shape of an Example. For example, it may be a triangle shape or a wave shape.

  In the embodiment, the shape of the stator 30 is not a strict cylindrical shape. Further, the shape of the intermediate ring 40 is not a strict ring shape. In the case where the stator 30 and the intermediate ring 40 do not have such a strict shape, the stator 30 and the intermediate ring 40 may be disposed substantially coaxially. For example, in the embodiment, that the axis of the inner peripheral surface 34 of the stator 30 and the axis of the center hole 47 of the intermediate ring 40 are coaxial is an example of the stator 30 and the intermediate ring 40 being arranged coaxially.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Electric motor 20: Motor housing 21: Side walls 22a-22c: Fixing portion 23, 25: Bearing housing 24: Housing cover 30: Stator 31: Stator core 32a-32c: Bolt penetration portion 33a-33c: Through hole 34: Inner peripheral surface 40: Intermediate rings 42a-42c, 44a-44c: Fastening portions 43a-43c, 45a-45c: Through hole 46: Bending portion 47: Center hole 50: Rotor 51: Shaft 52: Rotor core 53, 54: Bearing CL: Axis

Claims (1)

An electric motor in which a stator is fixed to a housing via a flat intermediate ring,
The stator is cantilevered on the housing via the intermediate ring disposed coaxially with the axis at one end in the axial direction thereof,
The intermediate ring is
Six fastening portions provided at equal intervals in the circumferential direction of the intermediate ring, and of the six fastening portions, three fastening portions provided at intervals of 120 degrees are connected to the stator. A fastening portion that is fastened and the remaining three fastening portions are fastened to the housing;
A bent portion that is provided at an intermediate position between adjacent fastening portions and is bent in the out-of-plane direction of the flat plate of the intermediate ring ;
An electric motor characterized by comprising:

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