Shaft ground ring and motor

Abstract

The utility model relates to a shaft grounding ring and motor. The utility model relates to a kind of shaft grounding ring for preventing bearing electric corrosion caused by leakage current, and more specifically, the shaft grounding ring of the utility model includes brush and a pair of shell;The brush contacts the outer peripheral surface of shaft to discharge leakage current flowing through shaft to outside;The pair of shell is arranged opposite each other relative to brush so as to surround brush;Wherein, the shaft grounding ring is facilitated to manufacture and assembly of component by reducing the number of components, and also includes flow path that cooling fluid can flow through.

Description

Technical Field

[0001] This utility model relates to a shaft grounding ring for preventing bearing electro-corrosion caused by leakage current generated in an electric motor. Background Technology

[0002] In recent years, electric vehicles have received considerable attention due to various factors, including environmental protection, a focus on renewable energy, and energy efficiency. Electric vehicles are typically equipped with an electric motor as a drive source to replace a conventional internal combustion engine; this electric motor generates rotational power from electrical energy.

[0003] An electric motor may include a housing, a stator fixedly mounted inside the housing, and a rotor that rotates about a shaft that serves as the drive shaft. Typically, the motor is driven in pulse-width modulation (PWM) mode via an inverter switch. In this configuration, a shaft voltage may be induced in the shaft, and leakage current from the motor may flow along the shaft, generating voltage spikes and causing bearing electro-corrosion, thereby damaging the bearing surface.

[0004] As electric motors are used as the primary drive source for electric vehicles, bearing electro-corrosion has become an increasingly significant problem. Bearing electro-corrosion can damage the bearing itself or shorten its service life, and in addition, bearing failure can lead to damage to the electric motor, reducer, and other components.

[0005] While the operating voltage of electric motors has been continuously increased to improve performance, this increase exacerbates bearing galvanic corrosion. Methods to prevent bearing galvanic corrosion include blocking current flow or venting current to the outside through a grounding system. One such method is using a shaft grounding ring (SGR), a component located near the bearing that contacts the shaft; it prevents bearing galvanic corrosion by allowing current flowing through the shaft to be vented to the outside through a housing.

[0006] However, conventional shaft grounding rings have the following limitations: they consist of multiple components, each with relatively high material costs, and the complexity of these components increases manufacturing costs. Furthermore, conventional shaft grounding rings may include structures that impede the flow of cooling fluid along the shaft, thereby degrading cooling performance. Utility Model Content

[0007] This invention was conceived to solve the above-mentioned problems, and its purpose is to provide a shaft grounding ring that can prevent bearing electro-corrosion. Unlike conventional structures, this shaft grounding ring has a simpler and easier-to-manufacture construction to reduce material costs and facilitate production, and forms a flow path for cooling fluid to improve the cooling performance of the motor.

[0008] According to the present invention, a shaft grounding ring attached to the shaft of an electric motor to block leakage current includes: a brush that contacts the outer peripheral surface of the shaft to discharge leakage current flowing through the shaft to the outside; and a pair of housings arranged facing each other relative to the brush and surrounding the brush.

[0009] In addition, the brush and housing are formed in a ring shape.

[0010] In addition, the brush and housing are formed in a C shape, which defines a portion of the circumference of a predetermined length.

[0011] In addition, the housing includes at least one connecting portion, which includes a pin protruding toward the brush and a hole corresponding to the pin, the connecting portion being arranged circumferentially.

[0012] Furthermore, the two housings are arranged facing each other on opposite sides of the brush, and a pin on the connecting part of one housing is fitted into a hole on the connecting part of the opposite housing, and the housings are assembled by press fitting.

[0013] In addition, the housing includes at least one through hole formed along the circumference of the housing to allow fluid to pass through the housing.

[0014] In addition, the housing includes a recess formed to a predetermined depth along the inner circumferential surface on the surface in contact with the brush, the recess accommodating a portion of the outer circumference of the brush.

[0015] In addition, the housing also includes at least one through hole formed through the housing along the outer circumferential surface.

[0016] In addition, the housing also includes at least one connecting portion located outside the area of ​​the through hole along the outer circumferential surface, the at least one connecting portion including a pin protruding toward the brush and a hole correspondingly recessed to the pin.

[0017] In addition, the brush is formed of at least one of conductive rubber, conductive carbon, or conductive fabric, and the housing is formed of a metallic material. Attached Figure Description

[0018] Figure 1 This is a partial cross-sectional view of a motor equipped with a conventional shaft grounding ring;

[0019] Figure 2 This is an exploded 3D view of a conventional shaft grounding ring;

[0020] Figure 3 This is a partial perspective view of an electric motor equipped with a shaft grounding ring according to an embodiment of the present invention;

[0021] Figure 4It is a cross-sectional view of an electric motor equipped with a shaft grounding ring according to an embodiment of the present invention;

[0022] Figure 5 This is a perspective view illustrating the overall structure of the shaft grounding ring according to an embodiment of the present invention;

[0023] Figure 6 This is an exploded perspective view of the shaft grounding ring according to an embodiment of the present invention;

[0024] Figure 7 This is a perspective view of a shaft grounding ring according to another embodiment of the present invention;

[0025] Figure 8 This is an exploded perspective view illustrating the overall structure of a shaft grounding ring according to another embodiment of the present invention;

[0026] Figure 9 This is a side view of the connecting portion of the shaft grounding ring according to the present invention; and

[0027] Figure 10 This is a conceptual diagram illustrating the flow of working fluid generated by a shaft grounding ring according to an embodiment of the present invention.

[0028] Explanation of reference numerals in the attached figures

[0029] 1: Shaft

[0030] 2: Bearings

[0031] 3: Outer shell

[0032] 4: Axis grounding ring

[0033] 110: Shell

[0034] 111: Through hole

[0035] 112: Depression

[0036] 120: Brush

[0037] 130: Connecting part

[0038] 131: Sales

[0039] 132: Kong Detailed Implementation

[0040] The technical aspects of this utility model will now be described in more detail with reference to the accompanying drawings. Prior to this, the terms and words used in the following description and claims should not be limited to their ordinary or dictionary meanings, but should be interpreted according to the principle that the inventor can appropriately define terms to best describe the utility model, and in accordance with the meaning and concept consistent with the technical concept of this utility model.

[0041] Therefore, the embodiments described in this specification and the structures shown in the accompanying drawings are only the most preferred embodiments of this utility model and do not fully represent the technical concept of this utility model. It should be understood that at the time of filing this application, there may be various modifications and equivalents that can replace them.

[0042] The technical aspects of this utility model will now be described in more detail with reference to the accompanying drawings. The drawings illustrate examples and are intended only to explain the technical spirit of this utility model more specifically, and the technical spirit of this utility model is not limited to the structures shown in the drawings.

[0043] This utility model relates to a shaft grounding ring 100, which is used to prevent electrical corrosion of bearing 2 caused by leakage current in motor. The shaft grounding ring 100 may be a component that is in contact with shaft 1 and is located adjacent to bearing 2, and is configured to discharge leakage current flowing through shaft 1 to the outside through housing 3.

[0044] Reference Figure 1 and Figure 2 A conventional shaft grounding ring 10 typically includes a brush 12, a housing 13, and a cover 11. The brush 12 directly contacts the shaft 1 and conducts electricity. The housing 13 houses the brush 12 and is assembled onto the motor housing 3. The cover 11 is press-fitted into the housing 13 to secure the brush 12. Here, the housing 13 and the cover 11 are formed in different shapes to perform different functions. Because the conventional shaft grounding ring 10 is assembled from three components of different shapes, it has many parts, resulting in a complex manufacturing process and relatively high cost, which limits its wide applicability. Furthermore, the cover 11 and the housing 13 block the space between the shaft 1 and the housing 3, partially hindering the flow of cooling fluid in the motor, thereby reducing cooling performance.

[0045] The shaft grounding ring 100 of this invention is designed to solve the above-mentioned problems, and is characterized by reducing the number of components and constructing each component to be easy to manufacture, thereby simplifying production and reducing costs. Furthermore, by forming a flow path that allows cooling fluid to pass through, the shaft grounding ring 100 of this invention improves cooling performance compared to conventional designs.

[0046] Reference Figure 3 and Figure 4 The shaft grounding ring 100 of this utility model is installed on the shaft 1 of an electric motor to block leakage current. The shaft grounding ring includes a brush 120 and a pair of housings 110. The brush 120 contacts the outer peripheral surface of the shaft 1 to discharge the leakage current flowing through the shaft 1 to the outside. The pair of housings 110 are arranged opposite to each other and around the brush 120.

[0047] The shaft grounding ring 100 of this invention is configured to discharge the leakage current generated in the motor to the housing 3 through the brush 120, and as... Figure 3 and Figure 4 As shown, the shaft grounding ring is formed to contact the shaft 1 to allow leakage current flowing through the shaft 1 to be discharged outward via the brush 120. The brush 120 is preferably formed of a conductive material to transmit the current flowing through the shaft 1; and since the brush 120 is in contact with the rotating outer peripheral surface of the shaft 1, it can be formed of a softer material to prevent surface damage. According to an embodiment of the present invention, the brush 120 is preferably formed of a soft and conductive material (such as conductive rubber obtained by mixing black pigment or metal fibers into insulating rubber, conductive carbon fibers formed by the same or different methods, or conductive fabric) to provide conductivity while maintaining surface softness.

[0048] Reference Figure 5 and Figure 6 The shaft grounding ring 100 of this invention is achieved by assembling a pair of housings 110, each housing 110 having the same shape and housing a brush 120, while connecting the brush 120 to the motor housing 3. The housing 110 consists of a first housing 110a and a second housing 110b, which are formed to the same shape but arranged facing each other relative to the brush 120. In other words, the first housing 110a and the second housing 110b, having the same shape, are located on opposite sides of the brush 120 facing each other, and by combining the first housing 110a and the second housing 110b, a housing 110 surrounding the brush 120 is formed.

[0049] With this construction, the shaft grounding ring 100 can be manufactured simply by forming the brush 120 and the first housing 110a and the second housing 110b, thereby reducing the number of parts compared to conventional designs. Furthermore, since the first housing 110a and the second housing 110b have the same shape, the housing 110 can be manufactured using a single production unit, thus simplifying both the manufacturing and assembly processes of the shaft grounding ring 100.

[0050] Reference Figure 6 and Figure 7 The housing 110 preferably connects the brush 120 to the motor housing 3 and is configured to conduct the current transmitted through the brush 120 to the housing 3. That is, the housing 110 is preferably arranged to contact both the brush 120 and the housing 3. The housing 110 is preferably formed of a conductive material capable of transmitting current and can be made of a relatively rigid material to serve as the housing 3 for housing and fixing the position of the brush 120. According to an embodiment of the present invention, the housing 110 can be formed of a metallic material.

[0051] The shaft grounding ring 100 of this invention can be mounted as a component on a motor. According to an embodiment, the shaft grounding ring 100 is formed in an annular shape and can be assembled onto the outer peripheral surface of the shaft 1. Therefore, as... Figure 6 and Figure 7 As shown, the brush 120 and housing 110 constituting the shaft grounding ring 100 have annular shapes. Since the inner circumferential surface of the brush 120 contacts the shaft 1, the inner diameter of the brush 120 is preferably equal to or greater than the outer diameter of the shaft 1. By forming the shaft grounding ring 100 into annular shape, it can be more stably mounted on the motor.

[0052] Reference Figure 8 and Figure 9 According to another embodiment of the present invention, the shaft grounding ring 100' has a C-shape forming a partial circumference. In other words, the shaft grounding ring 100' is constructed as a curved shape that contacts only a portion of the circumference of the shaft 1. Therefore, the brush 120' and housing 110' constituting the shaft grounding ring 100' also have a C-shaped bend of a predetermined length. Since the brush 120' only needs to make sufficient contact with the shaft 1 to conduct leakage current, the C-shaped design of the shaft grounding ring 100' reduces material costs while providing sufficient performance. The curvature of the shaft grounding ring 100' is preferably matched to the curvature of the shaft 1, and considering the characteristics of the brush 120', the bending length can be set to a minimum sufficient to transmit current.

[0053] The housing 110 of this invention is constructed as a pair of housings having the same shape. To form the shaft grounding ring 100, the brush 120 needs to be assembled with the housing 110. This invention is characterized in that the housing 110 includes a connecting device, and when a pair of housings 110 are assembled facing each other, they are connected by the connecting device formed on the housing 110. Figure 6 , Figure 8 and Figure 9 As shown, the housing 110 includes a connecting portion 130, which has a circumferentially arranged pin 131 protruding toward the brush 120, and a corresponding recessed hole 132. Specifically, as Figure 6 and Figure 8As shown, a connecting portion 130 is formed on a housing 110 (e.g., a first housing 110a and a second housing 110b, or a first housing 110a' and a second housing 110b'), and in a pair of housings 110 (e.g., a first housing 110a and a second housing 110b, or a first housing 110a' and a second housing 110b') arranged facing each other, the connecting portion 130 may be formed on the inner surface of the housings 110 that contacts each other. Here, this inner surface may correspond to the portion of the housing 110 that contacts the brush 120. The connecting portion 130 is configured as a collection of protruding pins 131 and recessed holes 132, and the pins 131 and holes 132 are arranged side by side along the circumference of the housing 110. Depending on the circumferential length of the housing 110 or as needed, the connecting portion 130 may be formed at one or more locations on the housing 110. In other words, to ensure a more robust connection between the housings 110, multiple connecting portions 130 may be arranged taking into account their area.

[0054] Reference Figure 9 The method of assembling a pair of housings 110 using a connecting portion 130 is described in more detail below. The pair of housings 110 may include a first housing 110a and a second housing 110b, which have the same shape and are arranged facing each other on opposite sides of a brush 120, thereby contacting each corresponding side of the brush 120. Each of the first housings 110a and the second housing 110b includes a number and shape of connecting portions 130. When the first housings 110a and the second housing 110b, each having a connecting portion 130, are positioned facing each other, the pins 131 and holes 132 of the connecting portions 130 are aligned in their relative positions. In this state, by assembling the first housings 110a and the second housing 110b into contact with each other, the connecting portions 130a of the first housing 110a and the connecting portions 130b of the second housing 110b are interlocked and assembled. In other words, the pin 131a of the connecting portion 130a of the first housing 110a is inserted into the hole 132b of the connecting portion 130b of the second housing 110b, or vice versa; the pin 131b of the connecting portion 130b of the second housing 110b is inserted into the hole 132a of the connecting portion 130a of the first housing 110a, or vice versa, thereby assembling the housing 110 and the brush 120. This assembly method using housings 110 formed with the same shape reduces the number of parts required to constitute the shaft grounding ring 100, simplifies both the manufacturing and assembly processes, and provides ease of assembly.

[0055] The housing 110 is configured to hold the brush 120, and preferably includes a portion therein where the brush 120 can be housed. (Refer to...) Figure 6 and Figure 8In this invention, the housing 110 has a recess 112 formed along its inner circumferential surface in the inner surface region where it contacts the brush 120. This recess 112 has a predetermined thickness and height. Here, the inner surface may correspond to the portion of the housing 110 that contacts the brush 120. The recess 112 is configured to accommodate the brush 120, and at least a portion of the outer periphery of the brush 120 is accommodated within the recess 112. That is, the outer periphery of the brush 120 contacts and is disposed within the inner circumferential surface of the housing 110. The depth of the recess 112 may be approximately half the thickness of the brush 120, and it is formed recessed from the inner surface region of the housing 110. Furthermore, the recess 112 is formed along the inner circumferential surface of the housing 110, and its height is determined according to the width of the brush 120 to be accommodated, and may occupy half or more or less than half the width of the housing 110.

[0056] Furthermore, the shaft grounding ring 100 of this invention is characterized by including a flow path through which cooling fluid can pass. The shaft grounding ring 100 contacts and connects to the housing 3 of the motor at the outer peripheral surface of the shaft 1. In the case of a conventional shaft grounding ring 100, the space between the shaft 1 and the housing 3 is blocked, which hinders the flow of cooling fluid and leads to a decrease in cooling performance. To solve this problem, the shaft grounding ring 100 of this invention is configured such that the housing 110 includes at least one through hole 111 of a predetermined length formed along the circumference of the housing 110.

[0057] Reference Figure 6 , Figure 8 and Figure 10 The through-hole 111 is a hole formed in the housing 110 in a direction parallel to the longitudinal direction of the shaft 1, through which cooling fluid can flow. The through-hole 111 may have a circular cross-section of a predetermined area and a predetermined length along the circumference of the housing 110, and its shape and number can be adjusted as needed. Since the brush 120 is mounted on the inner circumferential surface of the housing 110, it is preferable that the through-hole 111 for fluid flow is formed along the outer circumferential surface of the housing 110. In other words, at least one through-hole 111 is provided in the outer portion of the recess 112 that accommodates the brush 120. The housing 110 also includes a connecting portion 130. Preferably, the connecting portion 130 is formed at the portion where a pair of housings 110 contact, and therefore preferably in a region other than the portion accommodating the brush 120. Accordingly, the connecting portion 130 may be formed on the outer portion of the recess 112 and arranged in a region other than the through-hole 111. In other words, at least one connecting portion 130 and at least one through hole 111 may be provided along the outer circumferential surface of the housing 110, and they may be arranged at the desired positions along the circumference of the housing 110 to ensure that they do not overlap with each other.

[0058] The shaft grounding ring of this invention with the above-described structure has the following advantages: it can effectively ground and discharge leakage current generated in the shaft to prevent bearing electro-corrosion, thereby reducing bearing wear and damage, and extending the maintenance cycle and service life of the motor; it provides a simpler and easier-to-manufacture structure with fewer parts to reduce costs; it can be assembled and installed without additional expensive or complex devices, making it suitable for large-capacity motors; and it improves the cooling performance of the motor through a flow path that allows cooling fluid to pass through.

[0059] As described above, although the present invention has been described with reference to specific components and limited embodiments illustrated in the accompanying drawings, this description is provided only to facilitate a better understanding of the present invention, and the present invention is not limited to the illustrated embodiments. Those skilled in the art can make various modifications and variations based on the present disclosure.

[0060] Therefore, the spirit of this utility model is not limited to the described embodiments, and all elements covered by the appended claims, as well as any equivalents or variations thereof, fall within the scope of this utility model.

[0061] Cross-references to related applications

[0062] This application claims priority to Korean Patent Application No. 10-2024-0135339, filed on October 7, 2024, the entire contents of which are incorporated herein by reference for all purposes.

Claims

1. A shaft grounding ring, said shaft grounding ring being attached to the shaft of a motor to block leakage current, characterized in that, The shaft grounding ring includes: A brush, the brush contacting the outer peripheral surface of the shaft to discharge leakage current flowing through the shaft to the outside; and A pair of housings, the pair of housings being arranged facing each other relative to the brush, the pair of housings surrounding the brush.

2. The shaft grounding ring according to claim 1, characterized in that, The brush and the housing are formed in an annular shape.

3. The shaft grounding ring according to claim 1, characterized in that, The brush and the housing are formed in a C-shape, the C-shape defining a portion of a circumference of a predetermined length.

4. The shaft grounding ring according to claim 1, characterized in that, One of the pair of housings includes at least one connecting portion, the at least one connecting portion including a pin protruding toward the brush, and the other of the pair of housings includes at least one connecting portion, the at least one connecting portion of the other housing including a hole recessed corresponding to the pin, the at least one connecting portion of the one housing and the at least one connecting portion of the other housing being arranged along the circumference of the axial grounding ring.

5. The shaft grounding ring according to claim 4, characterized in that, The pair of housings are disposed facing each other on opposite sides of the brush, and the pin of the at least one connecting portion on one housing is fitted into the hole of the at least one connecting portion on the other housing, and the pair of housings are assembled by press fitting.

6. The shaft grounding ring according to claim 1, characterized in that, Each housing includes at least one through-hole formed along the circumference of each housing to allow fluid to pass through each housing.

7. The shaft grounding ring according to claim 1, characterized in that, Each housing includes a recess of a predetermined depth formed along the inner circumferential surface of each housing on the surface in contact with the brush, the recess accommodating a portion of the outer circumference of the brush.

8. The shaft grounding ring according to claim 7, characterized in that, Each housing also includes at least one through hole formed through each housing along the outer circumferential surface of each housing.

9. The shaft grounding ring according to claim 8, characterized in that, Each housing also includes at least one connecting portion located outside the region of the at least one through hole along the outer circumferential surface, the at least one connecting portion including a pin protruding toward the brush and a hole recessed in the at least one connecting portion.

10. The shaft grounding ring according to claim 9, characterized in that, The pin of at least one connecting portion on one of the pair of housings is fitted into the hole of at least one connecting portion on the other housing, and wherein the pin of at least one connecting portion on the other housing is fitted into the hole of at least one connecting portion on the first housing.

11. The shaft grounding ring according to claim 1, characterized in that, The brushes are formed of one of conductive rubber, conductive carbon, or conductive fabric, and each housing is formed of a metallic material.

12. An electric motor comprising a shaft, a housing, a stator disposed within the housing, and a rotor, characterized in that, The electric motor include: According to claim 1, the shaft grounding ring is in contact with the shaft.

Images