Electric motor
By setting the circumferential angle of the rib on the motor housing between 0.5θ and 1.5θ, the electric motor addresses axial and circumferential vibration issues, achieving enhanced vibration reduction through structural alignment and rigidity.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- MITSUBISHI HEAVY IND LTD
- Filing Date
- 2025-08-13
- Publication Date
- 2026-07-02
AI Technical Summary
Existing electric motors with stator cores and stator holders face challenges in effectively reducing axial and circumferential vibrations caused by electromagnetic exciting forces, as the setting of rib angles in relation to vibration modes is not adequately addressed, leading to insufficient vibration reduction.
The electric motor incorporates ribs on the motor housing inclined at a predetermined angle, with the circumferential angle from the rib's start to end point set between 0.5θ and 1.5θ, where θ is the angle obtained by dividing 360 degrees by the greatest common divisor of the stator's slots and rotor's poles, enhancing the motor's structural rigidity and vibration cancellation.
This configuration effectively reduces both axial and circumferential vibrations by ensuring appropriate alignment of vibration wave components, leveraging the motor's structural rigidity at fastening points to enhance vibration reduction.
Smart Images
Figure JP2025028562_02072026_PF_FP_ABST
Abstract
Description
Electric motor
[0001] The present disclosure relates to an electric motor.
[0002] Conventionally, in an electric motor in which a stator core around which a stator coil is wound is composed of a plurality of stator pieces divided in the circumferential direction, and the plurality of stator pieces are held by a cylindrical stator holder, a technique for reducing the action of electromagnetic exciting force caused by radial attractive force and repulsive force due to magnetism is known (see, for example, Patent Document 1).
[0003] The electric motor disclosed in Patent Document 1 is provided with a plurality of inclined ribs extending while being inclined in the axial direction on the outer peripheral surface of the stator holder. By increasing the rigidity of the stator holder in the axial direction and the circumferential direction with the plurality of inclined ribs, it is possible to reduce the axial vibration and circumferential vibration of the electric motor caused by the action of the electromagnetic exciting force.
[0004] Japanese Patent No. 6364444
[0005] In a stator and a motor housing that holds the stator, due to the action of the electromagnetic exciting force, vibration of the number of vibration modes (the number of waveforms in the circumferential direction) determined by the number of slots of the stator (the number of grooves that accommodate the coils wound around the teeth) and the number of poles of the rotor occurs. However, in Patent Document 1, there is no disclosure regarding how to set the circumferential angle of the region from the start point to the end point of the rib in relation to the number of vibration modes.
[0006] For example, if the length of the rib is not appropriately set with respect to the wavelength in the circumferential direction of the vibration wave generated according to the number of vibration modes, the circumferential vibration cannot be appropriately reduced by the rib. Thus, in Patent Document 1, there is room for improvement in reducing the axial vibration and circumferential vibration of the electric motor caused by the action of the electromagnetic exciting force.
[0007] The present disclosure has been made in view of such circumstances, and an object thereof is to provide an electric motor capable of appropriately setting the circumferential angle of the region from the start point to the end point of the rib formed in the motor housing and reducing both the axial vibration and circumferential vibration of the electric motor.
[0008] An electric motor according to one aspect of the present disclosure comprises a motor housing that extends along an axis and is formed in a cylindrical shape, and a motor housed inside the motor housing, wherein the motor has a stator fixed inside the motor housing and a rotor disposed on the inner circumference side of the stator, and a rib is formed on the outer circumferential surface of the motor housing that is formed to rotate in the circumferential direction around the axis and extends in a direction inclined at a predetermined angle from the direction along the axis, and when the angle obtained by dividing 360 degrees of one rotation in the circumferential direction by the greatest common divisor of the number of slots of the stator and the number of poles of the rotor is defined as θ, the circumferential angle in the region from the start point to the end point of the rib is set to be greater than 0.5θ and less than 1.5θ.
[0009] According to this disclosure, it is possible to provide an electric motor that can reduce both axial and circumferential vibrations of the electric motor by appropriately setting the circumferential angle of the region from the starting point to the ending point of the rib formed in the motor housing.
[0010] This is a perspective view showing an electric compressor according to one embodiment of the present disclosure. This is a perspective view showing a motor included in an electric compressor according to one embodiment of the present disclosure. This is a perspective view showing a motor housing, a first end housing, and a second end housing included in an electric compressor according to one embodiment of the present disclosure. This is an exploded view showing the outer circumferential surface of the motor housing of the first embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the second embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the third embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the fourth embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the fifth embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the sixth embodiment. This is an exploded view showing the outer circumferential surface of the motor housing of the seventh embodiment.
[0011] Hereinafter, an electric compressor (motor) 100 according to one embodiment of the present disclosure will be described with reference to the drawings. Figure 1 is a perspective view showing an electric compressor 100 according to one embodiment of the present disclosure. The electric compressor 100 shown in Figure 1 is used, for example, in an air conditioning system for a vehicle that regulates the temperature of the air inside the vehicle, and is a device that compresses a refrigerant drawn in from the outside.
[0012] As shown in Figure 1, the electric compressor 100 of this embodiment comprises a motor housing 10, a first end housing 11, a second end housing 12, a motor 20 housed inside the motor housing 10, and a compressor 30.
[0013] The motor housing 10 is a cylindrical member that extends along the axis X. The first end housing 11 seals one side of the motor housing 10 in the axial direction along the axis X. The second end housing 12 seals the other side of the motor housing 10 in the axial direction along the axis X. The motor housing 10, the first end housing 11, and the second end housing 12 form a sealed space in which the motor 20 and the compressor 30 are housed. The motor 20 rotates the compressor 30 around the axis X. The compressor 30 obtains driving force from the motor 20 and rotates around the axis X to compress the refrigerant.
[0014] Figure 2 is a perspective view showing a motor 20 of an electric compressor 100 according to one embodiment of the present disclosure. As shown in Figure 2, the motor 20 has a stator 21 fixed inside the motor housing 10 and a rotor 22 arranged on the axis X on the inner circumference side of the stator 21. In Figure 2, the coils wound around the teeth 21a of the stator 21 are not shown. The stator 21 of the motor 20 of this embodiment has 12 slots 21b along the circumferential direction CD. The rotor 22 of this embodiment has, for example, two poles.
[0015] Figure 3 is a perspective view showing the motor housing 10, the first end housing 11, and the second end housing 12 of an electric compressor 100 according to one embodiment of the present disclosure. In Figure 3, the shapes of the motor housing 10, the first end housing 11, and the second end housing 12 are shown in a simplified manner.
[0016] As shown in Figure 3, one side of the motor housing 10 in the direction of the axis X and the first end housing 11 are fastened together by a first fastening bolt (first fastener) 10c1 at a first fastening position P1 in the circumferential direction CD around the axis X. The other side of the motor housing 10 in the direction of the axis X and the second end housing 12 are fastened together by a second fastening bolt (second fastener) 10c2 at a second fastening position P2 in the circumferential direction CD around the axis X.
[0017] As shown in Figure 3, a plurality of ribs 10b are formed on the outer circumferential surface 10a of the motor housing 10. Now, referring to Figures 4 to 10, an embodiment of the ribs 10b formed on the outer circumferential surface 10a of the motor housing 10 will be described. As shown in Figures 4 to 10, the ribs 10b are formed on the outer circumferential surface 10a of the motor housing 10 so as to extend linearly in a direction inclined at a predetermined angle α from the direction along the axis X, and to pivot in the circumferential direction CD around the axis X.
[0018] In the stator 21 and the motor housing 10 that holds the stator 21, the electromagnetic excitation force in the stator 21 generates vibrations of a number of vibration modes (number of waveforms in the circumferential CD) determined by the number of slots in the stator 21 (number of grooves that accommodate the coils wound around the teeth 21a) and the number of poles in the rotor 22. The angle θ obtained by dividing 360 degrees, which is one full rotation of the circumferential CD, by the greatest common divisor of the number of slots in the stator and the number of poles in the rotor 22, is the angle of one wavelength of the vibration wave in the circumferential CD that is generated according to the number of vibration modes.
[0019] In this embodiment, the angle φ of the circumferential CD in the region from the start point to the end point of the rib 10b is set to be greater than 0.5θ and less than 1.5θ. If the angle φ is 0.5θ or less, the vibration wave generated in one rib 10b will be less than half a wavelength, resulting in a state where only one of the vibration wave components, either directed radially outward or radially inward around the axis X, acts on one rib 10b.
[0020] In this state, focusing on a single rib 10b, the phenomenon of canceling out vibration wave components does not occur at that rib 10b due to the combined action of both the vibration wave component directed radially outward and the vibration wave component directed radially inward. Therefore, in this embodiment, the angle φ is set to be greater than 0.5θ.
[0021] Furthermore, if the angle φ is 1.5θ or greater, the vibration wave generated in one rib 10b will be 1.5 wavelengths or greater, resulting in a situation where either the component of the vibration wave directed radially outward around the axis X or the component directed radially inward acts strongly on the rib 10b.
[0022] In this state, focusing on one rib 10b, a phenomenon occurs where the vibration wave components cancel each other outward and inward in the radial direction act on that rib 10b. However, one of the vibration wave components acts more strongly than the other, weakening the effect of canceling each other out. Therefore, in this embodiment, the angle φ is set to be smaller than 1.5θ.
[0023] In the above, the angle φ of the circumferential CD in the region from the start point to the end point of the rib 10b is set to be greater than 0.5θ and less than 1.5θ, but other embodiments are also possible. For example, the angle φ of the circumferential CD in the region from the start point to the end point of the rib 10b may be set to be greater than 0.8θ and less than 1.2θ.
[0024] In this embodiment, the stator 21 of the motor 20 has 12 slots 21b along the circumferential direction CD. Also, the rotor 22 in this embodiment has, for example, 2 poles. Therefore, the angle θ obtained by dividing the 360 degrees of one rotation of the circumferential direction CD by the greatest common divisor of the number of slots in the stator 21 (12) and the number of poles in the rotor 22 (2) is 180 degrees. In this embodiment, the angle φ of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b is set to be greater than 0.5θ and less than 1.5θ. In this embodiment, since θ is 180 degrees, the angle φ is set to be greater than 90 degrees and less than 270 degrees.
[0025] [First Embodiment] Figure 4 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the first embodiment, unfolded in the circumferential direction CD. In this embodiment, the motor housing 10 and the first end housing 11 are fastened together by first fastening bolts 10c1 at a plurality of first fastening positions P1 in the circumferential direction CD. In addition, in this embodiment, the motor housing 10 and the second end housing 12 are fastened together by second fastening bolts 10c2 at a plurality of second fastening positions P2 in the circumferential direction CD.
[0026] In this embodiment, multiple first fastening positions P1 and multiple second fastening positions P2 are arranged at 60-degree intervals in the circumferential direction CD. The first fastening positions P1 and the second fastening positions P2 are at the same position in the circumferential direction CD. The angle φ is set to θ (180 degrees in this embodiment). Multiple ribs 10b are formed at six locations on the outer circumferential surface 10a along the circumferential direction CD at 60-degree intervals. The angle φ in the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b coincides with the angle of one wavelength of the vibration wave generated in one rib 10b. Therefore, focusing on one rib 10b, both the vibration wave component directed radially outward and the vibration wave component directed radially inward act on that rib 10b for half a wavelength each, canceling out the vibration wave components.
[0027] In this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1, and the ending point 10b2 of the rib 10b coincides with the second fastening position P2. Since the starting point 10b1 and ending point 10b2 of the rib are positioned at the first fastening position P1 and the second fastening position P2, which have higher rigidity compared to other positions, the effect of reducing vibrations in the axial direction X and circumferential direction CD of the electric compressor 100 can be enhanced.
[0028] [Second Embodiment] Figure 5 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the second embodiment, unfolded in the circumferential direction CD. The second embodiment is a modification of the first embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0029] In the first embodiment, the starting point 10b1 of the rib 10b coincided with the first fastening position P1, and the ending point 10b2 of the rib 10b coincided with the second fastening position P2. In contrast, in this embodiment, the starting point 10b1 of the rib 10b does not coincide with the first fastening position P1, and the ending point 10b2 of the rib 10b does not coincide with the second fastening position P2. Even when the starting point 10b1 and ending point 10b2 of the rib are not positioned at the first fastening position P1 and the second fastening position P2, which have higher rigidity compared to other positions, the rib 10b can reduce vibrations of the electric compressor 100 in the axial direction X and circumferential direction CD.
[0030] [Third Embodiment] Figure 6 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the third embodiment, unfolded in the circumferential direction CD. The third embodiment is a modification of the first embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0031] In this embodiment, the angle φ is set to 4θ / 3 (240 degrees in this embodiment). Multiple ribs 10b are formed at three locations on the outer surface 10a along the circumferential direction CD at intervals of 120 degrees. The angle φ of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b coincides with the angle of 4 / 3 wavelength of the vibration wave generated in one rib 10b. Therefore, focusing on one rib 10b, both the vibration wave component directed radially outward and the vibration wave component directed radially inward act on that rib 10b, causing the vibration wave components to cancel each other out.
[0032] In this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1, and the ending point 10b2 of the rib 10b coincides with the second fastening position P2. Since the starting point 10b1 and ending point 10b2 of the rib are positioned at the first fastening position P1 and the second fastening position P2, which have higher rigidity compared to other positions, the effect of reducing vibrations in the axial direction X and circumferential direction CD of the electric compressor 100 can be enhanced.
[0033] [Fourth Embodiment] Figure 7 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the fourth embodiment, unfolded in the circumferential direction CD. The fourth embodiment is a modification of the first embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0034] In this embodiment, the angle φ is set to 2θ / 3 (120 degrees in this embodiment). Multiple ribs 10b are formed at six locations on the outer circumferential surface 10a along the circumferential direction CD at 60-degree intervals. The angle φ of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b coincides with the angle of 2 / 3 wavelength of the vibration wave generated in one rib 10b. Therefore, focusing on one rib 10b, both the vibration wave component directed radially outward and the vibration wave component directed radially inward act on that rib 10b, causing the vibration wave components to cancel each other out.
[0035] In this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1, and the ending point 10b2 of the rib 10b coincides with the second fastening position P2. Since the starting point 10b1 and ending point 10b2 of the rib are positioned at the first fastening position P1 and the second fastening position P2, which have higher rigidity compared to other positions, the effect of reducing vibrations in the axial direction X and circumferential direction CD of the electric compressor 100 can be enhanced.
[0036] [Fifth Embodiment] Figure 8 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the fifth embodiment, unfolded in the circumferential direction CD. The fifth embodiment is a modification of the fourth embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0037] In the fourth embodiment, the starting point 10b1 of the rib 10b coincided with the first fastening position P1, and the ending point 10b2 of the rib 10b coincided with the second fastening position P2. In contrast, in this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1, while the ending point 10b2 of the rib 10b does not coincide with the second fastening position P2.
[0038] In this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1. Since the starting point 10b1 of the rib is positioned at the first fastening position P1, which has higher rigidity compared to other positions, the effect of reducing vibrations in the axial direction X and circumferential direction CD of the electric compressor 100 can be enhanced. Furthermore, even if the ending point 10b2 of the rib is not positioned at the second fastening position P2, which has higher rigidity compared to other positions, the rib 10b can still reduce vibrations in the axial direction X and circumferential direction CD of the electric compressor 100.
[0039] [Sixth Embodiment] Figure 9 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the sixth embodiment, unfolded in the circumferential direction CD. The sixth embodiment is a modification of the first embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0040] In this embodiment, the angle φ is set to 2θ / 3 (120 degrees in this embodiment). Multiple ribs 10b are formed at three locations on the outer surface 10a along the circumferential direction CD at intervals of 120 degrees. The angle φ of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b coincides with the angle of 2 / 3 wavelength of the vibration wave generated in one rib 10b. Therefore, focusing on one rib 10b, both the vibration wave component directed radially outward and the vibration wave component directed radially inward act on that rib 10b, causing the vibration wave components to cancel each other out.
[0041] In this embodiment, the starting point 10b1 of the rib 10b coincides with the first fastening position P1, and the ending point 10b2 of the rib 10b coincides with the second fastening position P2. Since the starting point 10b1 and ending point 10b2 of the rib are positioned at the first fastening position P1 and the second fastening position P2, which have higher rigidity compared to other positions, the effect of reducing vibrations in the axial direction X and circumferential direction CD of the electric compressor 100 can be enhanced.
[0042] [Seventh Embodiment] Figure 10 is an exploded view of the outer circumferential surface 10a of the motor housing 10 of the seventh embodiment, unfolded in the circumferential direction CD. The seventh embodiment is a modification of the first embodiment and is the same as the first embodiment unless otherwise specifically described below, so the following description will be omitted.
[0043] In this embodiment, a plurality of first fastening positions P1 and a plurality of second fastening positions P2 are arranged at intervals of 72 degrees in the circumferential direction CD. In this embodiment, the angle φ is set to 4θ / 5 (144 degrees in this embodiment). A plurality of ribs 10b are formed at five locations on the outer peripheral surface 10a along the circumferential direction CD at intervals of 72 degrees. The angle φ of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b coincides with the angle of 4 / 5 wavelengths of the vibration wave generated in one rib 10b. Therefore, focusing on one rib 10b, in that rib 10b, components of the vibration wave directed radially outward and components of the vibration wave directed radially inward both act, and the components of the vibration wave cancel each other out.
[0044] In this embodiment, the starting point 10b1 of the rib 10b is made to coincide with the first fastening position P1, and the ending point 10b2 of the rib 10b is made to coincide with the second fastening position P2. Since the starting point 10b1 and the ending point 10b2 of the rib are arranged at the first fastening position P1 and the second fastening position P2 where the rigidity is higher compared to other positions, the effect of reducing the vibration in the axial direction X and the vibration in the circumferential direction CD of the electric compressor 100 can be enhanced.
[0045] The electric compressor 100 of the present embodiment described above exhibits the following operations and effects. In the electric compressor 100 of the present embodiment, when the angle of the circumferential direction CD in the region from the starting point 10b1 to the ending point 10b2 of the rib 10b is 0.5θ or less, the vibration wave generated in one rib 10b becomes half wavelength or less, and a state occurs in which only one of the components of the vibration wave directed radially outward around the axis X and the components of the vibration wave directed radially inward acts on one rib 10b. In this state, when focusing on one rib 10b, a phenomenon in which the components of the vibration wave are canceled out by the action of both the components of the vibration wave directed radially outward and the components of the vibration wave directed radially inward does not occur in that rib 10b.
[0046] Therefore, in the electric compressor 100 of the present embodiment, the angle φ is set to be greater than 0.5θ. In one rib 10b, components of the vibration wave directed outward in the radial direction and components of the vibration wave directed inward in the radial direction both act, and the components of the vibration wave can cancel each other out. Thus, by appropriately setting the angle φ in the circumferential direction CD of the region from the starting point 10b1 to the ending point 10b2 of the rib 10b formed on the motor housing 10, both the axial vibration and the circumferential direction CD vibration of the electric compressor 100 can be reduced.
[0047] Further, according to the electric compressor 100 of the present embodiment, since the starting point 10b1 and the ending point 10b2 of the rib 10b are arranged at the first fastening position P1 and the second fastening position P2 where the rigidity is higher compared to other positions, the effect of reducing the axial vibration and the circumferential direction CD vibration of the electric compressor 100 can be enhanced.
[0048] Also, according to the electric compressor 100 of the present embodiment, since the plurality of ribs 10b are formed so as to overlap in the circumferential direction CD, at each position in the circumferential direction CD, both the axial vibration and the circumferential direction CD vibration of the electric compressor 100 can be more reliably reduced.
[0049] The electric motors described in the above-described embodiments can be understood as follows, for example.
[0050] The electric motor according to the first aspect of the present disclosure includes a motor housing (10) that extends along an axis (X) and is formed in a cylindrical shape, and a motor (20) housed inside the motor housing. The motor has a stator (21) fixed inside the motor housing and a rotor (22) disposed on the inner peripheral side of the stator. On the outer peripheral surface (10a) of the motor housing, ribs (10b) are formed so as to extend in a direction inclined at a predetermined angle from the direction along the axis and to turn in the circumferential direction (CD) around the axis. When the angle obtained by dividing 360 degrees of one round in the circumferential direction by the greatest common divisor of the number of slots of the stator and the number of poles of the rotor is θ, the circumferential angle (φ) of the region from the starting point (10b1) to the ending point (10b2) of the rib is set to be greater than 0.5θ and less than 1.5θ.
[0051] In the electric motor according to the first aspect of this disclosure, if the circumferential angle of the region from the start point to the end point of the rib is 0.5θ or less, the vibration wave generated in one rib becomes less than half a wavelength, and a state occurs in which only one of the vibration wave components directed radially outward or radially inward acts on one rib. In this state, focusing on one rib, the phenomenon of canceling out the vibration wave components by both the radially outward and radially inward vibration wave components acting on that rib does not occur.
[0052] Therefore, in the electric motor according to the first aspect of this disclosure, the angle φ is set to be greater than 0.5θ. In a single rib, both the vibration wave component directed radially outward and the vibration wave component directed radially inward act on it, canceling out the vibration wave components. Thus, by appropriately setting the circumferential angle of the region from the start point to the end point of the rib formed in the motor housing, both axial vibration and circumferential vibration of the electric motor can be reduced.
[0053] An electric motor according to a second aspect of the present disclosure further comprises the following configuration in the first aspect: a first end housing (11) that seals one side of the motor housing in the axial direction, and a second end housing (12) that seals the other side of the motor housing in the axial direction, wherein one side of the motor housing in the axial direction and the first end housing are fastened together by a first fastener (10c1) at a plurality of first fastening positions (P1) in the circumferential direction, the other side of the motor housing in the axial direction and the second end housing are fastened together by a second fastener (10c2) at a plurality of second fastening positions (P2) in the circumferential direction, the circumferential position of the starting point of the rib coincides with the first fastening position, and the circumferential position of the ending point of the rib coincides with the second fastening position.
[0054] According to the electric motor of the second aspect of this disclosure, the start and end points of the rib are positioned at the first and second fastening positions, which have higher rigidity compared to other positions, thereby enhancing the effect of reducing axial and circumferential vibrations of the electric motor.
[0055] An electric motor according to a third aspect of this disclosure further comprises the following configuration in the first or second aspect: that is, a plurality of ribs are formed on the outer circumferential surface of the motor housing so as to overlap in the circumferential direction.
[0056] According to the electric motor of the third aspect of this disclosure, since multiple ribs are formed to overlap in the circumferential direction, both axial vibration and circumferential vibration of the electric motor can be more reliably reduced at each position in the circumferential direction.
[0057] An electric motor according to a fourth aspect of this disclosure further comprises the following configuration in the first or second aspect: that the circumferential angle from the starting point (10b1) to the ending point (10b2) of the rib is set to be greater than 0.8θ and less than 1.2θ.
[0058] According to the electric motor of the fourth aspect of this disclosure, by setting the circumferential angle from the start point to the end point of the rib to be greater than 0.8θ and less than 1.2θ, both axial vibration and circumferential vibration of the electric motor can be reduced more reliably.
[0059] An electric motor according to a fifth aspect of the present disclosure further comprises the following configuration in a second aspect: a compressor (30) disposed inside a sealed space formed by the motor housing, the first end housing, and the second end housing, which rotates around the axis to compress a refrigerant, and the motor rotates the compressor around the axis.
[0060] According to the fifth aspect of this disclosure, in an electric motor equipped with a compressor that is rotationally driven by a motor to compress a refrigerant, both axial vibration and circumferential vibration of the electric motor can be reduced.
[0061] 10 Motor housing 10a Outer surface 10b Rib 10b1 Starting point 10b2 Ending point 10c1 First fastening bolt (first fastener) 10c2 Second fastening bolt (second fastener) 11 First end housing 12 Second end housing 20 Motor 21 Stator 21a Teeth 21b Slot 22 Rotor 30 Compressor 100 Electric compressor CD Circumferential direction P1 First fastening position P2 Second fastening position X axis
Claims
1. An electric motor comprising: a motor housing extending along an axis and formed in a cylindrical shape; and a motor housed inside the motor housing, wherein the motor has a stator fixed inside the motor housing and a rotor positioned on the inner circumference side of the stator, and ribs are formed on the outer surface of the motor housing to extend in a direction inclined at a predetermined angle from the direction along the axis and to pivot in the circumferential direction about the axis, and when the angle obtained by dividing 360 degrees of one rotation in the circumferential direction by the greatest common divisor of the number of slots of the stator and the number of poles of the rotor is defined as θ, the circumferential angle in the region from the starting point to the ending point of the ribs is set to be greater than 0.5θ and less than 1.5θ.
2. The electric motor according to claim 1, comprising: a first end housing that seals one side of the motor housing in the direction along the axis; and a second end housing that seals the other side of the motor housing in the direction along the axis, wherein one side of the motor housing in the direction along the axis and the first end housing are fastened together by a first fastener at a plurality of first fastening positions in the circumferential direction; the other side of the motor housing in the direction along the axis and the second end housing are fastened together by a second fastener at a plurality of second fastening positions in the circumferential direction; the circumferential position of the starting point of the rib coincides with the first fastening position; and the circumferential position of the ending point of the rib coincides with the second fastening position.
3. The electric motor according to claim 1 or claim 2, wherein a plurality of ribs are formed on the outer circumferential surface of the motor housing so as to overlap in the circumferential direction.
4. The electric motor according to claim 1 or claim 2, wherein the circumferential angle of the rib from the starting point to the ending point is set to be greater than 0.8θ and less than 1.2θ.
5. The electric motor according to claim 2, comprising a compressor disposed inside a sealed space formed by the motor housing, the first end housing, and the second end housing, which rotates around the axis to compress a refrigerant, wherein the motor rotates the compressor around the axis.