Motor and car seat comprising the same

Abstract

The present application relates to a motor with high electromagnetic compatibility level, comprising a stator assembly, a rotor assembly and an end cover assembly, the stator assembly comprises a metal shell, the rotor assembly comprises a rotor core and a rotor shaft, the end cover assembly comprises an end cover, the shell comprises a first end provided with a bearing chamber and an open second end opposite to the first end, the motor is further provided with a metal cover, the cover is provided with a plurality of retaining tabs on its peripheral edge, the end cover is provided with a plurality of positioning protrusions on its peripheral outer surface, a positioning notch for cooperating with the positioning protrusions and a retaining notch for cooperating with the retaining tabs are arranged at the end edge of the second end of the shell, so that the rotor assembly and the end cover assembly are completely encapsulated in the shell by the cover, so that the motor as a whole is in a metal closed structure. The present application also relates to an automobile seat comprising the above motor. By using the motor according to the present application, electromagnetic radiation of the motor can be more effectively suppressed, and a very high EMC level can be obtained.

Description

Technical Field

[0001] This invention relates to the field of motor technology, and more specifically to a motor with a high level of electromagnetic compatibility (EMC) and an automotive seat including such a motor. Background Technology

[0002] With the development of science and technology, car seats are integrating more and more functions. To realize these functions, motors are being used more and more widely in the automotive field, especially in car seats. As seat motors used in automobiles, the working environment places very high demands on their electromagnetic compatibility (EMC). However, most known motors in the current technology cannot meet the high EMC requirements, especially in the automotive seat field, because these motors, especially DC brushed motors, cannot reduce the impact of electromagnetic waves through shielding during commutation and electromagnetic propagation.

[0003] An electric motor typically comprises a stator assembly with a metal casing, a rotor assembly including the rotor (composed of a rotor core and a rotor shaft), and end cover assemblies. For example, it is currently known that the end covers of motors are arranged primarily on the outside of the motor casing. This clearly fails to create a fully enclosed metal space for the entire motor, thus hindering the suppression of electromagnetic radiation. Furthermore, most brushed motors, due to significant rotor vibration during operation, instability during commutation resulting in substantial commutation sparks, and their conventional air gap structure, all contribute to negatively impacting electromagnetic radiation suppression.

[0004] Therefore, there is a need to propose an improved motor that can suppress electromagnetic radiation from one or more of the aforementioned aspects to a greater extent, thereby obtaining a motor with a high EMC level, which can then be better applied in the automotive field. Summary of the Invention

[0005] This invention is proposed against this background. According to one aspect of the invention, a motor with a high level of electromagnetic compatibility is provided, comprising a stator assembly, a rotor assembly, and an end cover assembly. The stator assembly includes a metal housing, the rotor assembly includes a rotor core and a rotor shaft, and the end cover assembly includes an end cover. The housing includes a first end with a bearing chamber and an open second end opposite to the first end. The motor is further provided with a metal cover, the cover having a plurality of retaining tabs on its periphery, and the end cover having a plurality of positioning protrusions on its circumferential outer surface. At the end edge of the second end of the housing, there are positioning notches for engaging with the positioning protrusions of the end cover and retaining notches for engaging with the retaining tabs, so that the rotor assembly and the end cover assembly are completely enclosed within the housing by the cover, thereby making the motor an overall metal enclosed structure.

[0006] Advantageously, the retaining tab includes an anti-detachment structure that prevents the cap from detaching from the housing in a direction away from the housing when the retaining tab is placed in the corresponding retaining notch.

[0007] Advantageously, the bearing chamber is provided with a bearing for rotatably supporting one end of the rotor shaft, the circumferential outer surface of the bearing including a first length section and a second length section, wherein the first length section is designed to mate with the inner wall of the bearing chamber, and the second length section extends beyond the bearing chamber.

[0008] Advantageously, a plurality of protruding teeth spaced apart from each other are provided on the circumferential outer surface of the bearing along the first length segment.

[0009] Advantageously, a circuit board is fixed to the end cap, on which a plurality of grounding wires are provided, the plurality of grounding wires being designed to contact the metal housing to achieve multiple grounding points.

[0010] Advantageously, the motor is a DC brushed motor, the stator assembly further includes a plurality of magnets arranged circumferentially within the housing, the end cover assembly further includes a brush assembly, and the rotor assembly further includes a commutator fixed to the rotor shaft.

[0011] Advantageously, the rotor assembly defines a rotor center, and the magnetic tile defines an arc-shaped inner edge that defines an arc center, wherein an eccentricity is defined between the arc center and the rotor center, such that an air gap is formed between the magnetic tile and the rotor core that gradually increases from the middle of the magnetic tile to both sides (i.e., thinner in the middle and thicker at both sides).

[0012] Advantageously, the brush assembly includes a brush holder and carbon brushes fixed to the brush holder. The brush holder includes a swing arm for holding the carbon brushes and a spring clip fixed to the end cap. The spring clip is provided with a material removal section, the size of which can be adjusted to adjust the force exerted by the carbon brushes on the commutator surface.

[0013] Advantageously, the material removal portion is an elongated hole formed on the spring and / or a notch formed at the outer periphery of the spring.

[0014] According to another aspect of the invention, a car seat is also provided, which includes the aforementioned motor.

[0015] Compared with the prior art, the structure for motors according to the present invention can achieve at least one of the following technical effects: The end cap and rotor assembly can be completely enclosed within the metal shell using a metal cover and an elongated metal outer shell structure, making the motor as a whole a metal-enclosed structure, effectively reducing the electromagnetic radiation emitted by the motor; the use of eccentric magnets creates an air gap between the magnets and the rotor that is thin in the middle and thick on both sides, forming a specific shape of surface magnetic curve after magnetization, reducing cogging torque fluctuations during motor rotation, and helping to suppress electromagnetic radiation; the advantageous structural design of the bearings and brush holders reduces rotor vibration, making the motor movement smoother during commutation and improving commutation sparking during motor operation; and the use of multiple grounding points on the circuit board helps to suppress electromagnetic radiation. Attached Figure Description

[0016] The above and other features and advantages of the present invention will become more readily understood from the following description with reference to the accompanying drawings, in which:

[0017] Figure 1 An exploded view and an assembly view of a motor in the prior art are shown;

[0018] Figure 2 An exploded view and an assembly view of a motor according to an embodiment of the present invention are shown;

[0019] Figures 3a to 3c The diagrams show the metal cap before the retaining tab is bent, after the retaining tab is bent, and when the entire assembly is placed on the housing.

[0020] Figure 4a The structure of the outer shell is shown in a three-dimensional diagram; Figure 4b The structure of the end cap is shown in a 3D diagram;

[0021] Figure 5 It shows that it includes Figure 2A cross-sectional schematic diagram of the motor housing and a partially enlarged schematic diagram of the bearing chamber (containing the bearing) located at one end of the housing;

[0022] Figures 6a-6b They are respectively shown in the container Figure 5 The diagram shows a perspective view and a cross-sectional view of the bearing inside the bearing chamber.

[0023] Figure 7a A cross-sectional schematic diagram of a magnetic tile fixedly arranged inside a housing is shown; Figure 7b The positional relationship between the rotor core and the magnetic tiles is shown; Figure 7c The eccentric setting between the rotor center and the arc center of the magnetic tile is shown;

[0024] Figure 8 A schematic diagram of the structure of the brush holder on which the carbon brush is fixed is shown; and

[0025] Figure 9a A schematic diagram of the circuit board designed to be fixed to the end cap is shown; and Figure 9b A schematic diagram of the assembly between the circuit board and the end cap is shown.

[0026] All accompanying drawings are schematic only and are not necessarily drawn to scale. Furthermore, they only show those parts necessary to illustrate the invention; other parts are omitted or merely mentioned. That is, the invention may include other parts besides those shown in the drawings. Detailed Implementation

[0027] In the following description, numerous specific details are set forth to enable those skilled in the art to fully understand the invention. However, it will be apparent to those skilled in the art that implementation of the invention may not include some of these specific details. The various aspects, features, embodiments, and advantages described below are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims. Terms such as "first," "second," etc., are used hereinafter to describe elements of this application; these terms are used only to distinguish individual elements and are not intended to limit the nature, sequence, order, or number of these elements. Furthermore, it should be noted that in this specification, identical and / or functionally identical technical features are represented by the same or similar reference numerals.

[0028] like Figure 1The diagram shows an exploded view and an assembly view of a prior art motor 1' (specifically, a permanent magnet DC brushed motor). The motor 1' includes a stator assembly, a rotor assembly, and an end cap assembly. The stator assembly includes a metal housing 2' and four magnets 3' fixed within the housing 2'. The rotor assembly includes a rotor core 4', a rotor shaft 6', and a commutator 7' fixed to the rotor shaft 6'. The end cap assembly includes an end cap 5' and a brush holder 9' that can be fixed to the end cap 5', on which carbon brushes 8' are fixedly held, intended to contact the commutator 7' on the rotor shaft 6'. However, by… Figure 1 As can be seen from the motor 1' shown (especially the assembly diagram of the motor), after the stator assembly, rotor assembly and end cover assembly are finally assembled, the end cover 5' is generally located outside the housing 2'. This prevents the motor from forming a fully enclosed metal space, resulting in the motor radiating strong electromagnetic waves, which affects the normal operation of electronic instruments in the car. This greatly limits the application of motors in the automotive field.

[0029] Therefore, this invention proposes a design scheme that optimizes the structure of the motor from multiple different aspects. The motor according to this invention is not only compact and easy to install, but also meets the requirements for high EMC ratings.

[0030] See details Figure 2 It illustrates a motor 1 according to an embodiment of the present invention, particularly a DC brushed motor. Figure 1 The motors shown have similar structures. Figure 2 The motor according to the invention shown includes a stator assembly, a rotor assembly, and an end cap assembly. The stator assembly includes a metal housing 2 and four magnets 3 circumferentially fixed within the housing. It should be understood that, depending on the motor structure, the number of magnets can be two, four, or other suitable quantities. The rotor assembly includes a rotor core 4, a rotor shaft 6, and a commutator 7 fixed to the rotor shaft 6. The end cap assembly includes an end cap 5 and a brush holder 9 fixed to the end cap 5, on which carbon brushes 8 are fixedly held, intended to contact the commutator 7 on the rotor shaft 6.

[0031] Compared to existing motors, the motor according to the present invention significantly improves and enhances the EMC level by reducing commutation sparking and by adopting a fully enclosed metal structure to maximize shielding against external electromagnetic radiation. The structural improvements to various aspects of the motor will be described in detail below.

[0032] See especially Figure 4a as well as Figure 5The motor housing 2 includes a first end with a bearing chamber 13 and an open second end opposite the first end. The bearing chamber 13 houses a bearing 12 (e.g., an oil-impregnated bearing) for rotatably supporting one end of a rotor shaft. The outer surface of the bearing 12 includes a first length segment L1 and a second length segment L2, wherein the first length segment is designed to mate with the inner wall of the bearing chamber 13, and the second length segment extends beyond the bearing chamber 13 (see [link to relevant documentation]). Figures 6a-6b A stop portion 14 is formed between the first length segment L1 and the second length segment L2 due to the change in the outer surface diameter of the bearing to provide a stop for the bearing 12 received in the bearing chamber 13. Compared with ordinary oil-impregnated bearings known in the prior art, the bearing of the present invention has an extended segment that extends beyond the bearing chamber. This increases the support area between the motor rotor shaft 6 and the bearing 12 when the space of the bearing chamber is limited, thereby increasing the overall contact stiffness, changing the natural frequency of the rotor under constrained conditions, helping the rotor avoid the resonant frequency, thereby reducing rotor vibration, making the movement during the motor commutation process smoother, improving commutation sparks during motor operation, and advantageously suppressing the electromagnetic radiation of the motor. Furthermore, advantageously, in order to make the bearing 12 more stably held in the bearing chamber 13, a plurality of protruding teeth 15 spaced apart from each other are provided on the circumferential outer surface of the bearing 12 along the first length segment L1 (see... Figure 6a ).

[0033] As discussed above, Figure 1 In the motor shown, the end of the end cap 5' is encapsulated by a metal cover 10', which has two lugs 10a' on its periphery, designed to be press-fitted into the slot of the end cap 5'. However, due to Figure 1 The outer casing 2' cannot completely cover the end cap 5', resulting in the end cap being mostly outside the outer casing, which is very detrimental to suppressing the electromagnetic radiation of the motor.

[0034] Therefore, the present invention proposes an improved structure. See especially... Figures 3a-3c as well as Figures 4a-4b According to the present invention, the motor is provided with a metal cover 10. The outer dimensions of the cover 10 are close to the internal space dimensions of the housing 2, so that the cover 10 can be embedded in the end of the housing 2 and can form a sealed space after assembly with the housing. Specifically, the cover 10 is provided with a plurality of retaining tabs 10a on its periphery, and the end cap 5 is provided with a plurality of positioning protrusions 5a on its circumferential outer surface (see...). Figure 4bAt the second end of the outer casing 2 (i.e., the end opposite to the first end where the bearing chamber is located), a positioning notch 2a is provided for engaging with the positioning protrusion 5a of the end cover 5, and a retaining notch 2b is provided for engaging with the retaining tab 10a, so that the rotor assembly and the end cover assembly are completely enclosed within the outer casing 2 by the cover 10 (e.g., Figure 2 (as shown in the image).

[0035] See especially Figures 3a-3b The cover 10 and its retaining tab 10a are preferably integrally formed plates. When installing the cover 10 onto the housing 2, the retaining tab 10a on the cover 10 only needs to be bent and snapped into the corresponding retaining notch 2b in the housing 2. The retaining tab 10a includes an anti-detachment structure, which prevents the cover 10 from falling off the housing 2 in a direction away from the housing 2 when the retaining tab 10a is placed in the corresponding retaining notch 2b. As an example, the anti-detachment structure can be a circular protrusion. Of course, other forms of anti-detachment structures are also feasible, as long as they can prevent the cover from accidentally falling off.

[0036] Since the end cap 5 can be held on the housing 2 by means of the positioning protrusion 5a, and since the cover 10 can abut against the end surface of the end cap 5 to firmly hold the end cap 5, the housing 2 and the cover 10 as a whole, the motor as a whole has a metal enclosed structure, which advantageously reduces or suppresses the electromagnetic radiation of the motor to the outside.

[0037] See also Figures 7a-7c The rotor assembly defines the rotor center O1. Each magnet 3, arranged circumferentially inside the outer casing 2, defines an arc-shaped inner edge, which defines an arc center O2 with a radius R1. The rotor core 4 has a radius R2. An eccentricity e is defined between the arc center O2 and the rotor center O1, creating an air gap 20 between the magnet 3 and the rotor core 4 that gradually increases in size from the center of the magnet 3 to both sides (i.e., thinner in the middle and thicker at the edges). Unlike the uniform air gaps often used in existing technologies, this air gap structure allows for the formation of a specific shaped surface magnetic curve after magnetization, reducing cogging torque fluctuations during motor rotation and significantly suppressing electromagnetic radiation. This is highly beneficial for improving the motor's EMC level.

[0038] As discussed above, as a DC brushed motor, the end cap assembly of this motor may include a brush assembly. Figure 8As shown, the brush assembly includes a brush holder 9 and carbon brushes 8 fixed to the brush holder 9. The brush holder 9 includes a swing arm 9a for holding the carbon brushes 8 and a spring piece 9b fixed to the end cap 5. For example, the spring piece 9b is provided with a through hole 16 for a pin (not shown) to pass through so as to fix the brush holder 9 to the end cap 5 using the pin. Advantageously, the spring piece 9b is also provided with a material removal part. Preferably, the material removal part is an elongated hole 17 formed on the spring piece and / or a notch 18 formed at the outer periphery of the spring piece. For example, by changing the size of the elongated hole, the elasticity of the swing arm can be adjusted to adjust the force of the carbon brush acting on the commutator surface, thereby improving the commutation spark of the motor.

[0039] See also Figures 9a-9b A circuit board 11 is fixed or soldered onto the end cover 5 of the motor. This circuit board has multiple grounding wires 19, which are designed to contact the metal casing 2 to achieve multiple grounding points. This differs from the circuit board structure with a single grounding wire commonly used in the prior art. By using multiple (two or more) grounding points on the circuit board, electromagnetic radiation can be better suppressed. Furthermore, multiple grounding points allow for a greater common reference zero potential across all circuit units, thus ensuring stable operation of the circuit system.

[0040] In the actual assembly process of the motor, after the stator assembly (press-fitting of bearings and installation of magnets in the housing, etc.), rotor assembly (installation of the commutator and winding of the rotor, etc.), and end cover assembly (press-fitting of bearings, installation and fixing of brush holder assembly, and circuit board soldering, etc.) are completed, the rotor assembly and end cover assembly are installed into the housing. Finally, a metal cover (such as an iron cover) is used to tightly adhere to the surface of the end cover and fix it to the housing, completing the overall sealing of the motor. The resulting integrated metal enclosed structure, along with the beneficial structural improvements to the motor components, greatly shields the motor from external electromagnetic radiation, improves commutation sparking, and significantly enhances the motor's EMC rating.

[0041] It should be noted that the embodiments described above should be considered exemplary only, and the present invention is not limited to these embodiments. By considering the content of this specification, those skilled in the art can make various changes and modifications without departing from the scope or spirit of the invention. The true scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An electric motor (1) comprising a stator assembly, a rotor assembly, and an end cover assembly, the stator assembly comprising a metal housing (2), the rotor assembly comprising a rotor core (4) and a rotor shaft (6), the end cover assembly comprising an end cover (5), the housing (2) comprising a first end having a bearing chamber (13) and an open second end opposite the first end, characterized in that, The motor (1) is also provided with a metal cover (10), the cover is provided with a plurality of retaining tabs (10a) on its periphery, the end cover (5) is provided with a plurality of positioning protrusions (5a) on its circumferential outer surface, and the end edge of the second end of the housing (2) is provided with a positioning notch (2a) for cooperating with the positioning protrusions (5a) of the end cover and a retaining notch (2b) for cooperating with the retaining tabs (10a), so that the rotor assembly and the end cover assembly are completely enclosed in the housing by the cover (10), thereby making the motor as a whole a metal enclosed structure; The bearing chamber (13) is provided with a bearing (12) for rotatably supporting one end of the rotor shaft (6); the bearing is an oil-impregnated bearing; the outer surface of the bearing includes a first length section (L1) and a second length section (L2), wherein the first length section is designed to mate with the inner wall of the bearing chamber, and the second length section extends beyond the bearing chamber and extends out of the housing of the motor; a plurality of protruding teeth (15) spaced apart from each other are provided on the circumferential outer surface of the bearing (12) along the first length section (L1); The motor is a square DC brushed motor, and the stator assembly also includes a plurality of magnetic tiles (3) arranged circumferentially inside the housing; the magnetic tiles have a structure that is thick in the middle and thin at both sides, and define three planar outer surfaces and one curved inner surface; the rotor assembly defines a rotor center (O1), and the inner surface of the magnetic tile (3) defines an arc-shaped inner edge, which defines an arc center (O2), wherein an eccentricity (e) is defined between the arc center and the rotor center, so that an air gap (20) gradually increases from the middle of the magnetic tile to both sides is formed between the magnetic tile and the rotor core; The end cap assembly further includes a brush assembly, and the rotor assembly further includes a commutator (7) fixed on the rotor shaft (6). The brush assembly includes a brush holder (9) and carbon brushes (8) fixed to the brush holder. The brush holder includes a swing arm (9a) for holding the carbon brushes and a spring piece (9b) fixed to the end cap. The spring piece is provided with a material removal part, the size of which can be adjusted to adjust the force exerted by the carbon brushes on the commutator surface. The material removal part consists of an elongated hole (17) formed on the spring piece (9b) and a notch (18) formed at the outer periphery of the spring piece.

2. The motor (1) according to claim 1, characterized in that, The retaining tab (10a) includes an anti-detachment structure that prevents the cap (10) from falling out of the housing (2) in a direction away from the housing when the retaining tab (10a) is placed in the corresponding retaining notch (2b).

3. The motor (1) according to claim 1, characterized in that, A circuit board (11) is fixed on the end cap (5), on which a plurality of grounding wires (19) are provided, the plurality of grounding wires being intended to contact the metal housing (2) to achieve multiple grounding points.

4. A car seat, characterized in that, The car seat includes a motor (1) according to any one of claims 1 to 3.

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