Stator for electric motor
By incorporating sound-absorbing or structural damping elements into the stator body of the electric motor, the problem of noise generation during operation is solved, effective noise reduction is achieved, silent performance is improved, and the disadvantages of increasing volume and mass are avoided.
Patent Information
- Application Number
- CN202380072807.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-10-14
- Filing Date
- 2023-10-11
- Publication Date
- 2025-05-27
AI Technical Summary
Existing electric motors generate noise during operation, especially vibration and noise caused by high-frequency microdisplacement caused by the stator under the action of electromagnetic force. Existing solutions such as packaging stator or enhancing sound insulation but have the disadvantage of increasing volume and mass or not reducing noise diffusion.
A stator for electric motors is designed with a sound-absorbing or structural damping element built into the stator body, and a sound-absorbing or structural damping element is formed by injecting a filler material into the inner cavity of the stator body to reduce vibration and noise generated by the stator during operation.
With built-in sound-absorbing or structural damping elements, the noise generated by the electric motor during operation is effectively reduced, the silent performance of the motor is improved, while avoiding the disadvantages of increasing the motor volume and mass.
Smart Images
Figure CN120051913A_ABST
Abstract
Description
[0001] The invention relates to a stator for an electric motor. The invention also relates to an electric motor comprising such a stator.
[0002] In general, current electric motors comprise a rotor fixed to a shaft and a stator surrounding the rotor. The stator is mounted in a housing comprising bearings for the rotational mounting of the shaft. The rotor comprises a body formed by a stack of laminations or a pole wheel (claw pole) held in the form of a stack by means of a suitable fastening system. The body of the rotor comprises an inner cavity accommodating a permanent magnet. The stator comprises a body consisting of a stack of laminations forming a crown, the inner face of the body being provided with teeth, which define a plurality of slots two by two, which are open towards the inside of the stator body and are intended to receive phase windings. These phase windings pass through the slots of the stator body and are formed in winding heads protruding from both sides of the stator body. The phase windings may, for example, consist of a plurality of U-shaped conductor segments, the free ends of two adjacent segments being connected together by welding.
[0003] During their operation, electric motors often generate noises that can be irritating to people nearby. These noises can be mechanical and are caused by impacts or friction between mechanical parts during the rotation of the rotor. These noises can also be magnetic and are caused by the magnetic forces generated by the current flowing in the electric motor. In fact, these magnetic forces can make the structure of the electric motor vibrate at audible frequencies (from 20 Hz to 20 kHz), and these vibrations are transmitted through the structure to the ambient air, thus generating noise.
[0004] In particular, the stator can be subjected to micro-displacements at high frequencies and within the audible range of the human ear under the action of electromagnetic forces. These vibrations are then transmitted to the rest of the structure of the electric motor.
[0005] In order to reduce the noise pollution generated by the electric motor, one of the solutions currently under consideration consists in partially encapsulating the stator or in fully encapsulating the stator. Nevertheless, this solution has the disadvantage of increasing the volume and mass of the electric motor. Another possible solution consists in reinforcing the sound insulation between the motor compartment and the habitable interior of the vehicle. However, this solution has the disadvantage of not being able to reduce the noise diffused to the outside of the vehicle.
[0006] One of the objects of the present invention is therefore to propose a solution to the problem of noise pollution generated by an electric motor as described above, and in particular to propose a solution making it possible to reduce the noise generated by the stator.
[0007] To this end, the invention relates to a stator for an electric motor, the stator comprising:
[0008] - a stator body forming a crown extending along the axis between a front face and a rear face, said stator body comprising an outer peripheral face and an inner peripheral face provided with teeth defining, two by two, a plurality of slots open towards the inside of the stator body;
[0009] - a plurality of conductor segments at least partially inserted into the slots of the stator body;
[0010] Characterized in that the stator body is provided with at least one inner cavity, which accommodates at least one sound absorbing or structural damping element, and the at least one sound absorbing or structural damping element is capable of attenuating vibrations and / or mechanical noise and / or magnetic noise generated by the stator during its operation in the electric motor.
[0011] Thus constructed, the stator of the present invention makes it possible to reduce the noise generated during its operation due to the presence of elements capable of absorbing mechanical noise and / or magnetic noise and / or damping vibrations inside the inner cavity of the stator body.
[0012] The stator of the present invention may also include one or more of the following features:
[0013] - the at least one inner cavity comprises a main section forming an annulus around the axis of the stator body, a plurality of so-called first front sub-sections extending from the main section towards the front face of the stator body and a plurality of so-called second rear sub-sections extending from the main section towards the rear face of the stator body.
[0014] Each front and rear sub-section is rectilinear and oriented obliquely relative to the main section.
[0015] - Each front and rear sub-section is rectilinear and oriented perpendicularly to the main section.
[0016] The front and rear subsections form a tubular hole with a parallelepiped base.
[0017] - Each sub-segment is defined by a width B measured in an orthogonal radial direction and a length D measured in the radial direction. The width B is proportional to the width A of the segment formed by the teeth and the slots as measured in the orthogonal radial direction, the ratio between the width B and the width A being preferably comprised between 0.25 and 0.75, and the length D is proportional to the distance C separating the inner end edge of the slot from the outer peripheral surface of the stator body as measured in the radial direction, the ratio between the length D and the distance C being preferably comprised between 0.25 and 0.75.
[0018] The stator body comprises at least one radial opening which projects into a central section of the at least one inner cavity on one side and is located at the outer circumference of the stator body on the other side, the at least one radial opening allowing a filling material to be injected into the interior of the at least one inner cavity.
[0019] The stator comprises a plurality of through-bores which project into one of the front or rear subsections on one side and are located at the front or rear face on the other side, the through-bores being configured to allow the passage of air but not of filling material.
[0020] The through-going orifice is cylindrical in shape and has a diameter comprised between 0.02 mm and 0.2 mm.
[0021] - The at least one sound absorbing or structural damping element has a shape that is complementary to the shape of the at least one inner cavity.
[0022] - said at least one sound absorbing or structural damping element is made of a material selected from the group consisting of silicone materials, thermoplastic elastomers and heavy masses.
[0023] The invention also relates to an electric motor comprising a stator as defined above.
[0024] The invention will be better understood by reading the following non-limiting description given with reference to the accompanying drawings.
[0025] Figure 1 is a perspective view of an electric motor incorporating a stator according to the present invention.
[0026] Figure 2 yes Figure 1 A cross-sectional view of the motor is shown in FIG.
[0027] Figure 3 It is equipment Figure 1 A three-dimensional view of the stator of a motor.
[0028] Figure 4 yes Figure 3 Front axial view of the stator.
[0029] Figure 5 yes Figure 3 A cross-sectional view of the body of the stator along the section plane P.
[0030] Figure 6 According to the first embodiment Figure 3 A three-dimensional view of the body of a stator, the outer peripheral layer of the body has been removed to expose the inner cavity.
[0031] Figure 7 yes Figure 6 A top view of the stator is shown in FIG.
[0032] Figure 8 According to the second embodiment Figure 3 A three-dimensional view of the body of a stator, the outer peripheral layer of the body has been removed to expose the inner cavity.
[0033] Fig. 9 yes Figure 8 A top view of the stator is shown in FIG.
[0034] Fig.10 yes Figure 3 Front axial view of the structural details of the stator body.
[0035] Throughout the description and claims, the terms "axial" and "radial" and their derivatives are defined relative to a longitudinal axis along which the stator extends and through the center of the stator. Thus, an axial orientation refers to an orientation parallel to the longitudinal axis of the stator, and a radial orientation refers to an orientation perpendicular to the longitudinal axis of the stator. Furthermore, by convention, the terms "front" and "rear" refer to individual positions along the longitudinal axis of the stator. In particular, the term "front" corresponds to the portion of the stator adjacent to the end of the rotor shaft, to which a pulley, a pinion, a groove intended to transmit the rotational motion of the rotor to any other similar motion transmitting device can be fixed. Thus, the term "rear" corresponds to the portion of the stator adjacent to the other end of the rotor shaft.
[0036] Reference Figure 1 , shows an electric motor 1 embodied with a stator according to the invention. This electric motor 1 comprises in particular a housing 2 formed in two parts, housing a rotor 3, rotationally fixed to a shaft 4 mounted rotatably about an axis X, and an annular stator 5 surrounding the rotor 3 coaxially with the shaft 4. The housing 2 comprises in particular a front bearing 24 and a rear bearing 25 connected to each other by means of fixing screws 23. The bearings 24, 25 are hollow in shape and each of the bearings 24, 25 carries centrally a ball bearing 21 and 22, respectively, for the rotational mounting of the shaft 4.
[0037] The rear bearing 25 includes a bell-shaped cover, which is Figure 2 2 , the motor 200 is shown in the mounted position of the motor 200 , which completely covers the cylindrical portion 242 of the front bearing 24 extending axially from the end face 241 of said front bearing 24, said face 241 having the shape of a disk oriented in a plane perpendicular to the axis X of the shaft 4. The rear bearing 25 rests at the end edge 251 on a shoulder 243 defined by the end face 241.
[0038] The rear bearing 25 has a shape that is substantially complementary to that of the cylindrical portion 242 of the front bearing 24, so that in the mounted position of the motor, this portion 242 is in sealing contact with the inner wall 252 of the rear bearing 25, the sealing being ensured by two seals 8 of annular shape housed inside two annular grooves 7 formed on the periphery of the portion 242. The grooves 7 are arranged on either side of a region 244 of lower thickness of the part 242. The region 244 forms together with the inner wall 252 of the rear bearing 25 an internal channel 9 for the circulation of a liquid. Thus, the channel 9 allows a cooling liquid, such as, for example, water, glycol or oil, to circulate around the cylindrical portion 242 of the front bearing 24. Thus, during operation of the motor 1, the heat released by the stator 5 and transferred to the front bearing 24 can be transferred directly to the cooling liquid circulating in the internal channel 9. Thus, a faster cooling of the stator 5 can be obtained. In case the front bearing 24 is made of a material with high thermal conductivity, such as aluminum for example, and the rear bearing 25 is made of a material with low thermal conductivity, such as plastic material for example, the heat transfer to the cooling liquid is further improved. The cooling liquid supply will be through a liquid inlet pipe 26 formed at the periphery of the rear bearing 25, which leads to the internal channel 9. The cooling liquid outlet will be through a liquid outlet pipe 27 formed at the periphery of the rear bearing 25, which also extends into the internal channel 9.
[0039] Reference Figure 3 and Figure 4 , showing the equipment Figure 1 and Figure 2 The stator 5 of a motor. The stator 5 comprises a body 50 in the form of a crown, which extends along the axis X between a front face 51 and a rear face 52. The body 50 is made up of a stack of laminations held in the form of a stack by means of a suitable fixing system. The body 50 comprises a substantially cylindrical outer peripheral surface 53 and an inner peripheral surface 54, the inner peripheral surface 54 being provided with teeth 55 extending parallel to the axial direction X and regularly spaced around the circumference of the body 50. The teeth 55 delimit, two by two, a plurality of slots 56 intended to at least partially accommodate a plurality of U-shaped conductor segments 57. Thus, two consecutive slots 56 are separated by a tooth 55, as shown in FIG. Figure 5 The slots 56 open axially to the front end face 51 and the rear end face 52 of the stator body 50 , and open radially to the inner peripheral surface 54 of the body 50 .
[0040] like Figure 5As shown, the body 50 is also provided with a number of radial openings 58 on its outer circumferential surface 53. These radial openings 58 lead to an inner cavity 60 formed inside the stator body 50. These radial openings 58 will therefore make it possible to inject a filling material (not shown) inside the inner cavity 60. The filling material will in particular have specific properties that make it particularly suitable for attenuating vibrations and / or mechanical noise and / or magnetic noise generated by the stator during its operation in the electric motor.
[0041] Therefore, the filling material can be advantageously selected from silicone materials, thermoplastic elastomers (e.g. Type or PP / EPDM type thermoplastic elastomer) and heavy quality materials.
[0042] Once the injection operation is complete, the filling material will form a sound absorbing or structural damping element that will completely fill the inner cavity 60. Thus, the sound absorbing or structural damping element will have a shape that is complementary to the shape of the inner cavity 60. Therefore, the sound reduction effect obtained by means of the sound absorbing or structural damping element will depend on the shape of the inner cavity 60.
[0043] exist Figure 6 to Figure 7 and Figures 8 to 9 In the embodiment of the present invention, two preferred shapes of the inner cavity have been shown respectively. These preferred shapes obviously do not limit the invention. At this level, any other shape of the inner cavity that can effectively reduce the noise generated by the stator can be envisaged. In particular, several inner cavities separated from each other can be provided for the stator, each inner cavity accommodating a specific sound absorption or structural damping element.
[0044] Reference Figure 6 and Figure 7 , shows a first embodiment of a stator body according to the present invention. In this embodiment, the inner cavity 60 includes a main section 61 forming an annular member around the axis X of the stator body 50 and several sub-segments 62a, 62b extending from the main section 61 toward the end faces 51, 52 of the stator body 50, respectively, the one extending from the main section 61 toward the front end face 51 is called the front sub-segment 62a and the one extending from the main section 61 toward the rear end face 52 is called the rear sub-segment 62b. Each of the front sub-segment 62a and the rear sub-segment 62b is linear and oriented obliquely relative to the main section 61. In Figure 7 In the configuration shown, the front subsection 62a is parallel to the same direction D1 and the rear subsection 62b is parallel to the same direction D2, the direction D1 forming an angle α with the direction D2. This angle α will preferably be comprised between 30° and 120°.
[0045] exist Figure 6 In the configuration shown, the front subsection 62a and the rear subsection 62b comprise a tubular shape with a parallelepiped base. Fig.10, these sub-segments 62a, 62b will be defined by a width B measured in an orthogonal radial direction and a length D measured in a radial direction. The width B may be proportional to the width A of the segment formed by the teeth 55 and the slots 56 as measured in an orthogonal radial direction. In particular, the ratio between the width B and the width A may be comprised between 0.25 and 0.75. Similarly, the length D may be proportional to the distance C as measured in a radial direction separating the inner end edge of the slot 56 from the outer peripheral wall 53 of the stator body 50. In particular, the ratio between the length D and the distance C may be comprised between 0.25 and 0.75.
[0046] According to other configurations of the invention (not shown), the secondary section may also comprise a tubular shape with a circular base.
[0047] like Figure 6 As shown, the stator body 50 is also provided with a plurality of first through-holes 59a and second through-holes 59b. Each of the first through-holes 59a leads to one of the front sub-sections 62a on one side and is located at the front end face 51 on the other side, and each of the second through-holes 59b leads to one of the rear sub-sections 62b on one side and is located at the rear end face 52 on the other side. The first through-holes 59a and the second through-holes 59b will serve as vents during the operation of injecting the filling material into the interior of the inner cavity 60, thereby preventing the formation of air pockets inside the stator body. Therefore, the through-holes 59a, 59b must be wide enough to allow air to pass through, and must be narrow enough to prevent the filling material from passing through.
[0048] Reference Figure 8 and Fig. 9 , shows a second embodiment of the stator body according to the present invention. Figure 6 and Figure 7 The embodiment of is different in that each front sub-section 62 a and rear sub-section 62 b is oriented perpendicularly to the main section 61 .
[0049] exist Figure 8 In the configuration shown, the front subsection 62a and the rear subsection 62b comprise a tubular shape with a parallelepiped base. Fig.10, these sub-segments 62a, 62b will be defined by a width B measured in an orthogonal radial direction and a length D measured in a radial direction. The width B may be proportional to the width A of the segment formed by the teeth 55 and the slots 56 as measured in an orthogonal radial direction. In particular, the ratio between the width B and the width A may be comprised between 0.25 and 0.75. Similarly, the length D may be proportional to the distance C as measured in a radial direction separating the inner end edge of the slot 56 from the outer peripheral wall 53 of the stator body 50. In particular, the ratio between the length D and the distance C may be comprised between 0.25 and 0.75.
[0050] According to other configurations of the invention (not shown), the secondary section may also comprise a tubular shape with a circular base.
[0051] like Figure 8 As shown, the stator body 50 is also provided with a plurality of first through-holes 59a and second through-holes 59b. Each of the first through-holes 59a leads to one of the front sub-sections 62a on one side and is located at the front end face 51 on the other side, and each of the second through-holes 59b leads to one of the rear sub-sections 62b on one side and is located at the rear end face 52 on the other side. The first through-holes 59a and the second through-holes 59b will be used as exhaust holes during the operation of injecting the filling material into the inner cavity 60, thereby preventing the formation of air pockets inside the stator body. Therefore, the through-holes 59a, 59b must be wide enough to allow air to pass through, and must be narrow enough to prevent the filling material from passing through. In particular, the through-holes 59a, 59b can be cylindrical in shape and have a diameter included between 0.02mm and 0.2mm.
Claims
1. A stator (5) for an electric motor (1), the stator (5) include: - a stator body (50) forming a crown extending along the axis (X) between a front face (51) and a rear face (52), the stator body (50) comprising an outer peripheral face (53) and an inner peripheral face (54), the inner peripheral face (54) being provided with teeth (55) defining, two by two, a plurality of slots (56) open towards the inside of the stator body (50); - a plurality of conductor segments (57) which are at least partially inserted into the slots (56) of the stator body (50); The invention is characterized in that the stator body (50) is provided with at least one inner cavity (60), and the at least one inner cavity (60) accommodates at least one sound absorbing or structural damping element, and the at least one sound absorbing or structural damping element is capable of attenuating vibrations and / or mechanical noise and / or magnetic noise generated by the stator (5) during its operation in the electric motor (1).
2. The stator (5) according to claim 1, It is characterized in that The at least one inner cavity (60) comprises a main section (61) forming an annular member around the axis (X) of the stator body (50), a plurality of so-called first front sub-segments (62a) extending from the main section (61) toward the front end face (51) of the stator body (50), and a plurality of so-called second rear sub-segments (62b) extending from the main section (61) toward the rear end face (52) of the stator body (50).
3. The stator (5) according to claim 2, It is characterized in that Each of the front sub-section (62a) and the rear sub-section (62b) is linear and oriented obliquely relative to the main section (61).
4. The stator (5) according to claim 2, It is characterized in that Each of the front sub-section (62a) and the rear sub-section (62b) is rectilinear and oriented perpendicularly to the main section (61).
5. The stator (5) according to any one of claims 2 to 4, It is characterized in that The front subsection (62a) and the rear subsection (62b) form a tubular hole having a parallelepiped base.
6. The stator (5) according to claim 5, It is characterized in that Each sub-segment (62a, 62b) is defined by a width B measured in an orthogonal radial direction and a length D measured in a radial direction. Said width B is orthogonally proportional to a width A of the segment formed by the teeth (55) and the slots (56) as measured in an orthogonal radial direction, the ratio between said width B and said width A being preferably comprised between 0.25 and 0.75, and said length D is proportional to a distance C separating the inner end edge of the slots (56) from said outer peripheral surface (53) of said stator body (50) as measured in a radial direction, the ratio between said length D and said distance C being preferably comprised between 0.25 and 0.
75.
7. The stator (5) according to any one of claims 2 to 6, It is characterized in that The stator body (50) comprises at least one radial opening (58), which on one side extends into a central section (61) of the at least one inner cavity (60) and on the other side is located at the level of the outer peripheral surface (53) of the stator body (50), and the at least one radial opening (58) allows the injection of filling material into the interior of the at least one inner cavity (60).
8. The stator (5) according to claim 7, It is characterized in that The stator (5) comprises a plurality of through holes (59a, 59b) which project into one of the front subsection (62a) or the rear subsection (62b) on one side and are located at the level of the front face (51) or the rear face (52) on the other side, the through holes (59a, 59b) being configured to allow air to pass through without allowing the filling material to pass through.
9. The stator (5) according to claim 8, It is characterized in that Said through-going orifices (59a, 59b) are cylindrical in shape and have a diameter comprised between 0.02 mm and 0.2 mm.
10. Stator (5) according to any one of the preceding claims, It is characterized in that The at least one sound absorbing or structural damping element has a shape that is complementary to the shape of the at least one interior cavity (60).
11. Stator (5) according to any one of the preceding claims, It is characterized in that The at least one sound absorbing or structural damping element is made of a material selected from the group consisting of silicone materials, thermoplastic elastomers and heavy masses.
12. An electric motor (1) comprising a stator (5) according to any one of the preceding claims.