End cap assembly for an electric machine and electric machine

Abstract

The utility model relates to a kind of end cover assembly for motor, and motor comprising the end cover assembly of this end cover assembly.End cover assembly includes the first end cover made of plastic material and the second end cover made of metal material;Wherein, the second end cover has closed end and open end defined with opening;Second end cover is set to first end cover via opening cover and completely covers first end cover and with first end cover each other fixedly assembled together;End cover assembly aims at cooperation with motor housing to jointly define an electromagnetic shielding structure;Formed with the stop structure for limiting the axial displacement of the bearing of motor at the closed end of the second end cover.According to the end cover assembly of the utility model can cooperate with motor housing to jointly define an electromagnetic shielding structure, improve electromagnetic compatibility level, while also can limit the axial displacement of bearing by means of the stop structure on the second end cover, improve the service life of motor.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and more specifically to an end cover assembly for a motor and a motor including the end cover assembly. Background Technology

[0002] With the advancement of technology, the degree of electronic integration is increasing, and in fields such as automobiles and aerospace, the requirements for the electromagnetic interference resistance of electronic components in electronic systems are becoming increasingly stringent. As for brushed DC motors used in automobiles, the operating environment places extremely high demands on their electromagnetic compatibility.

[0003] A typical permanent magnet brushed DC motor usually consists of a stator with fixed main magnetic poles and brushes, and a rotor with armature windings and a commutator. The stator is integrated into the motor housing. Electrical energy from a DC power supply enters the armature windings through the brushes and commutator, generating armature current. The magnetic field generated by the armature current interacts with the main magnetic field to produce electromagnetic torque, causing the motor to rotate and drive the load. For brushed DC motors, the presence of brushes and the commutator causes commutation sparks during commutation, resulting in significant electromagnetic interference (EMI) during motor operation.

[0004] However, most existing brushed DC motors use plastic end caps, and the metal casing of the motor alone cannot achieve satisfactory electromagnetic shielding, making the motor unable to meet the high electromagnetic compatibility (EMC) requirements of certain applications. Furthermore, the plastic end caps of existing motors use a multi-lobed fixing structure with barbed hooks or stop protrusions to limit the ball bearings on the rotor shaft. Under extreme axial forces or abnormal operation, the fixing lobes can open, causing undesirable axial displacement of the motor armature and ball bearings, affecting the normal operation of the motor. Utility Model Content

[0005] The purpose of this utility model is to solve at least one of the above-mentioned problems and / or other problems existing in the prior art.

[0006] To achieve the above objectives, this utility model provides an end cap assembly for a motor, the motor including a motor housing made of a metal material, the end cap assembly including a first end cap made of a plastic material and a second end cap made of a metal material; wherein the second end cap has a closed end and an open end defining an opening; the second end cap is disposed on the first end cap via the open end cap and completely covers the first end cap and is fixedly assembled with the first end cap; the end cap assembly is intended to cooperate with the motor housing to jointly define an electromagnetic shielding structure; wherein a stop structure for limiting axial displacement of the motor bearing is formed at the closed end of the second end cap.

[0007] In one embodiment, the first end cap extends partially into the motor housing and is fixed to the motor housing with an interference fit, and the second end cap is fitted onto the first end cap with an overfit and at least completely covers the joint between the first end cap and the motor housing.

[0008] In one embodiment, the first end cap includes a first end cap body and at least two stop claws extending axially away from the outer end wall of the first end cap body. The at least two stop claws are arranged circumferentially spaced along the first end cap body to define an installation space for receiving the bearing, and the bearing is mounted to stop on the stop protrusions of the stop claws. The second end cap includes a second end cap body and a limiting boss, the limiting boss constituting the stop structure and extending axially away from the outer end wall of the second end cap body to form a receiving chamber. The receiving chamber is used to receive the at least two stop claws and prevent the at least two stop claws from expanding radially outward and prevent axial displacement of the bearing.

[0009] In one embodiment, the at least two stop claws together define a circumferential outer surface and an end outer surface, and the limiting boss includes a circumferential section and an end section respectively covering the circumferential outer surface and the end outer surface.

[0010] In one embodiment, the limiting boss is integrally formed with the second end cap body.

[0011] In one embodiment, a threaded hole is provided on the outer end wall of the first end cap body, and a through hole is provided on the outer end wall of the second end cap body, so that fasteners can pass through the through hole on the second end cap body and be threaded into the threaded hole of the first end cap body, thereby fixing the second end cap and the first end cap to each other.

[0012] In one embodiment, an opening is provided on the outer end wall of the second end cover body, and the circuit board of the motor is arranged at the opening.

[0013] In one implementation, the second end cap is in the form of an iron cap.

[0014] According to another aspect of the present invention, an electric motor is provided, wherein the second end cover is in the form of an iron cover.

[0015] According to another aspect of the present invention, an electric motor is provided, the electric motor comprising a motor housing having a housing opening at one end and an end cap assembly as described above, wherein a first end cap in the end cap assembly is connected to the motor housing at the housing opening, and a second end cap is connected to the first end cap and the motor housing.

[0016] In one implementation, the motor is a permanent magnet brushed DC motor.

[0017] The end cap assembly according to this utility model, by providing a second end cap made of metal material and covering it over the first end cap, completely covers the first end cap and the joint between the first end cap and the motor housing, thereby jointly defining an electromagnetic shielding structure. This prevents the electromagnetic energy released by components such as brushes and commutators during operation from causing electromagnetic interference to other electronic systems in the vehicle, thus improving electromagnetic compatibility. Furthermore, by forming a stop structure at the closed end of the second end cap, any axial displacement or even dislodgement of the bearings for the motor rotor shaft installed in the first end cap can be prevented. Attached Figure Description

[0018] The features and advantages of this utility model will become clear from the following detailed description provided with reference to the accompanying drawings. It should be understood that the following drawings are merely schematic and not necessarily drawn to scale, and therefore should not be considered as limitations on this utility model, wherein:

[0019] Figure 1 A perspective view of a motor according to an embodiment of the present invention is shown;

[0020] Figure 2 It shows Figure 1 An exploded view of the motor in the image;

[0021] Figure 3 A schematic diagram is shown of the bearing for the motor rotor shaft being stopped by a stop pawl in a plastic end cap (hereinafter referred to as "first end cap").

[0022] Figure 4 It shows Figure 3 A schematic diagram showing the axial displacement of a bearing due to the radial outward expansion of the stop claw; and

[0023] Figure 5 It shows Figure 3 A schematic diagram showing the bearing being installed in a plastic end cap and the stop claws being prevented from expanding outward and the bearing from shifting axially by the limiting boss of the metal shielding cap (hereinafter referred to as the "second end cap"). Detailed Implementation

[0024] Embodiments of the present invention are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement the present invention. However, it will be apparent to those skilled in the art that implementations of the present invention may not include some of these specific details. Furthermore, it should be understood that the present invention is not limited to the specific embodiments described. Rather, the present invention can be conceived to be implemented with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.

[0025] The terms "first" and "second" are used below to describe the elements of this application. These terms are used only to distinguish the individual elements and not to limit the nature, order, or number of these elements. The terms "comprising" and "having" are used to indicate an open-ended inclusion and mean that there may be additional elements / components besides those listed.

[0026] To prevent the motor from radiating excessive electromagnetic waves during operation, which could affect the normal operation of electronic systems in vehicles, the motor preferably adopts an overall enclosed metal structure. Specifically, this invention proposes an optimized end cap assembly, which mainly achieves electromagnetic shielding by fixing the end cap assembly to the motor housing in a suitable manner, forming a fully enclosed metal space with the motor's metal housing, effectively improving the motor's EMC level. Furthermore, this improved end cap assembly effectively prevents bearing displacement under extreme conditions, thus preventing disruption to the motor's normal operation. Therefore, the motor of this invention has a long lifespan and a high level of electromagnetic compatibility.

[0027] Specifically, Figure 1 and Figure 2 A perspective view and an exploded view of a motor according to an embodiment of the present invention are shown respectively. For example... Figures 1-2 As shown, the motor according to this embodiment may include a motor body, an end cover assembly 20, and a bearing 30 (e.g., ...). Figures 3 to 5 (As shown). The motor body may include a motor housing 10 made of metal material and a rotor assembly (not specifically shown) with armature windings and a commutator mounted within the motor housing 10. The motor housing 10 defines a housing cavity with a housing opening, in which an oil-impregnated bearing may be press-fitted and a magnet may be fixedly mounted. Two carbon brushes (not shown) intended to contact the commutator may be provided inside the end cover assembly. Therefore, this motor is preferably a permanent magnet brushed DC motor.

[0028] Reference Figure 1 and Figure 2According to this embodiment, the end cap assembly 20 can be used in a motor (especially a permanent magnet brushed DC motor) and may include a plastic end cap made of plastic material, i.e., a first end cap 1, and a metal shielding cover made of metal material, i.e., a second end cap 2. Two carbon brushes are disposed inside the first end cap 1. The first end cap 1 extends into the motor housing 10 through the housing opening of the motor housing 10 and is fixed to the motor housing 10 to form the motor body, while at least a portion of the first end cap 1 is disposed outside the motor housing 10.

[0029] The second end cap 2 has a generally closed end (except for the gap at the mounting hole) and an open end that are opposite each other along its axial direction. The open end defines an opening 23, which allows the second end cap 2 to be placed on the first end cap 1 through the opening 23 after the first end cap 1 is assembled to the motor housing 10, completely covering the portion of the first end cap 1 exposed in the motor housing 10, and then fixedly assembled together with the first end cap 1. At the same time, the end cap assembly 20 can cooperate with the motor housing 10 to jointly define a metal closed structure (except for the gap at the mounting hole), forming an electromagnetic shielding structure, thereby effectively reflecting and absorbing the radiated noise generated during motor operation, achieving good internal shielding of electromagnetic waves and suppressing the outward radiation of electromagnetic waves.

[0030] Optionally, the first end cover 1 can be fixed to the motor housing 10 by an interference fit. For example, the outer periphery of the first end cover 1 is also provided with sealing grooves spaced circumferentially. When the first end cover 1 is partially inserted into the motor housing 10 and the two are in an interference fit, under the stamping action of the sealing machine, the motor housing 10 can be punched out with four bending surfaces (which constitute the "sealing part") and pressed into the sealing grooves of the first end cover 1. In this way, the first end cover 1 is firmly formed as an integral part with the motor housing 10. Figure 2 As shown.

[0031] The inner diameter of the second end cover 2 at the opening 23 is approximately equal to or slightly larger than the outer diameter of the first end cover 1, thereby allowing the second end cover 2 to be fitted onto the first end cover 1 in a transition fit manner. The second end cover 2 can extend on the motor housing 10 to completely cover the joint between the first end cover 1 and the motor housing 10, thereby improving the electromagnetic compatibility of the motor.

[0032] Figure 3 and Figure 4 A specific example is shown where the motor bearing 30 is mounted on the first end cover 1. (Refer to reference...) Figure 2 and Figure 4The first end cap 1 may include a first end cap body 11 and at least two stop claws 12. The first end cap body 11 is generally cylindrical and has an outer end wall 111 at its end exposed above the motor housing 10, on which an end cap hole 13 is provided. At least two stop claws 12 are arranged circumferentially around the end cap hole 13 along the first end cap body 11 and extend axially away from the outer end wall of the first end cap body 11 to define a mounting space for the bearing 30 together with the stop claws 12 and other sections located between the stop claws. Each stop claw 12 has a stop protrusion at its end for providing axial stop restraint on the bearing 30.

[0033] When assembling the bearing 30, only an axial force needs to be applied to the bearing 30 toward the first end cover body 11. At this time, the bearing 30 will force the stop pawl 12 to expand radially outward so that it can enter the installation space and one end abuts against the outer end wall 111, while the other end abuts against the stop protrusion of the stop pawl 12. Figure 3 As shown, at least two stop claws 12 together define a circumferential outer surface α and an end outer surface β. When at least two stop claws 12 are in a normal, undeformed state, i.e., when the bearing 30 is stopped within the installation space, the outer diameter of the circumferential outer surface α is d1.

[0034] However, see Figure 4 Under extreme axial force or abnormal operation, the motor may experience radial outward expansion of the stop claws 12, causing the maximum outer diameter defined by at least two stop claws 12 to become d2. In this case, the bearing 30 may move axially beyond the stop protrusions, or even fall out of the mounting space. To prevent any undesirable axial displacement of the bearing, a stop structure is formed at the closed end of the second end cover 2.

[0035] Specifically, in conjunction with reference Figure 2 and Figure 5 The second end cap 2 may include a second end cap body 21 and a limiting boss 22. The second end cap body 21 includes a peripheral wall 211 and an outer end wall 212 connected to one axial end of the peripheral wall 211. The limiting boss 22 extends from the outer end wall 212 of the second end cap body 21 in an axial direction away from the second end cap body 21 and includes a circumferential section 221 and an end section 222. The end section 222 is connected to an axial end of the circumferential section 221 opposite to the first end cap 1, such that the limiting boss 22 forms a generally cap-shaped receiving chamber and covers the circumferential outer surface α via the circumferential section 221 and the end outer surface β via the end section 222. Thus, the circumferential section 221 can prevent the stop pawl 12 from expanding radially outward along the first end cap body 11. Furthermore, the end section 222 can provide axial stopping for the bearing 30.

[0036] Optionally, the limiting boss 22 and the second end cap body 21 can be formed as a single piece by stamping or other integral molding methods. Furthermore, the second end cap 2 is preferably made of iron.

[0037] See back Figure 1 and Figure 2 A threaded hole (not shown) may be provided on the outer end wall 111 of the first end cover body 11, and a through hole 213 corresponding to the threaded hole is provided on the outer end wall 212 of the second end cover body 21, so that the fastener 40 can pass through the through hole 213 of the first end cover body 11 and be threaded into the threaded hole of the second end cover body 21, thereby keeping the second end cover 2 and the first end cover 1 fixed, and further fixing the second end cover 2 and the motor housing 10.

[0038] Continue to refer to Figure 2 As shown, the motor according to this embodiment of the present invention may further include a circuit board 50. An opening 214 is also provided on the outer end wall 212 of the second end cover body 21, allowing the circuit board 50 to be arranged in a detachable or non-detachable manner at the opening 214. For example, the circuit board 50 can be placed inside the opening 214 and fixed to the second end cover body 21 by a non-detachable method (e.g., soldering). Alternatively, the circuit board 50 can be placed inside the opening 214 and fixed to the second end cover body 21 via other fixing structures (e.g., elastic fixing pieces). The shape and size of the opening 214 can be determined according to the actual needs of the circuit board 50.

[0039] When assembling the entire motor, first press-fit the oil-impregnated bearing into the motor housing 10 and fix the magnets in place. Then, install the commutator onto the rotor and complete the winding. Finally, install the entire rotor assembly into the motor housing 10. Next, insert the first end cover 1 into the motor housing 10 and cover the first end cover 1 with the second end cover 2. Then, fix the wiring harness and circuit board to the hole 214 by soldering or other means, and finally use fasteners 40 (such as fastening screws) to fasten the second end cover 2 to the first end cover 1 and the motor housing 10 to complete the assembly.

[0040] The end cap assembly of this invention features a second end cap made of metal that covers the first end cap, completely enclosing the first end cap and the joint between the first end cap and the motor housing. This collectively defines an electromagnetic shielding structure, preventing electromagnetic energy released by components such as brushes and commutators during operation from causing electromagnetic interference to other electronic systems in the vehicle, thus improving electromagnetic compatibility (EMC). Furthermore, a stop structure formed at the closed end of the second end cap prevents any axial displacement or even dislodgement of the bearings for the motor rotor shaft mounted in the first end cap. Therefore, the motor according to this invention has a long lifespan and a high EMC level.

[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 contents of this specification, those skilled in the art can make various changes and modifications without departing from the scope or spirit of the present invention. The true scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. An end cap assembly for an electric motor, the electric motor comprising a motor housing (10) made of a metallic material, characterized in that, The end cap assembly (20) includes a first end cap (1) made of plastic material and a second end cap (2) made of metal material; The second end cap has a closed end and an open end defining an opening (23); the second end cap is disposed on the first end cap via the open end cap and completely covers the first end cap and is fixedly assembled with the first end cap; the end cap assembly is intended to cooperate with the motor housing to jointly define an electromagnetic shielding structure; Among them, a stop structure for limiting the axial displacement of the bearing (30) of the motor is formed at the closed end of the second end cover.

2. The end cap assembly according to claim 1, characterized in that, The first end cap (1) extends partially into the motor housing (10) and is fixed to the motor housing in an interference fit manner. The second end cap (2) is fitted onto the first end cap in an overfit manner and at least completely covers the joint between the first end cap and the motor housing.

3. The end cap assembly according to claim 1 or 2, characterized in that, The first end cap (1) includes a first end cap body (11) and at least two stop claws (12) extending axially away from the first end cap body from the outer end wall (111) of the first end cap body. The at least two stop claws are arranged circumferentially spaced along the first end cap body to define an installation space for receiving the bearing (30), which is mounted to stop on the stop protrusions of the stop claws. The second end cap (2) includes a second end cap body (21) and a limiting boss (22). The limiting boss (22) constitutes the stop structure and extends axially away from the second end cap body from the outer end wall (212) of the second end cap body to form a receiving chamber. The receiving chamber is used to receive the at least two stop claws and prevent the at least two stop claws from expanding radially outward and prevent the bearing from shifting axially.

4. The end cap assembly according to claim 3, characterized in that, The at least two stop claws (12) together define the circumferential outer surface (α) and the end outer surface (β), and the limiting boss (22) includes a circumferential section (221) and an end section (222) respectively covering the circumferential outer surface and the end outer surface.

5. The end cap assembly according to claim 3, characterized in that, The limiting boss (22) is integrally formed with the second end cap body (21).

6. The end cap assembly according to claim 3, characterized in that, The outer end wall (111) of the first end cap body is provided with a threaded hole, and the outer end wall (212) of the second end cap body is provided with a through hole (213), so that the fastener (40) can pass through the through hole on the second end cap body and be threaded into the threaded hole of the first end cap body, thereby keeping the second end cap and the first end cap fixed to each other.

7. The end cap assembly according to claim 3, characterized in that, An opening (214) is also provided on the outer end wall (212) of the second end cover body, and the circuit board (50) of the motor is arranged at the opening.

8. The end cap assembly according to claim 1 or 2, characterized in that, The second end cap is made of iron.

9. An electric motor, characterized in that, The device includes a motor housing (10) having a housing opening at one end and an end cap assembly (20) according to any one of claims 1 to 8, wherein a first end cap (1) in the end cap assembly is connected to the motor housing (10) at the housing opening, and a second end cap (2) is connected to the first end cap (1) and the motor housing.

10. The motor according to claim 9, characterized in that, The motor is a permanent magnet brushed DC motor.

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