Grounding structure for driving motor

Abstract

Disclosed is a grounding structure of a driving motor applied to an environmental protection vehicle, the driving motor including a rotating shaft rotatably supported by a bearing, a motor housing surrounding the bearing and the rotating shaft, the grounding structure disposed in a direction in which the rotating shaft extends, and a cover mounting the grounding structure therein and connected to the motor housing. Specifically, the grounding structure is in contact with the rotating shaft through a grounding unit, thereby grounding the rotating shaft.

Description

TECHNICAL FIELD

[0001] The present invention relates to a grounding structure of a driving motor for grounding a rotating shaft of the driving motor. BACKGROUND

[0002] The statements in this section merely provide background information related to the present invention and do not constitute prior art.

[0003] Recently, pure electric environmentally friendly vehicles such as electric vehicles, fuel cell vehicles, etc. have attracted attention. Such electric environmentally friendly vehicles are equipped with a motor (hereinafter referred to as a driving motor) that obtains rotational power from electric energy, not from an internal combustion engine or the like, as a driving source.

[0004] The driving motor used as a power source of an environmentally friendly vehicle includes a housing, a stator fixedly installed inside the housing, and a rotor arranged with a predetermined gap from the stator and rotating around a rotating shaft as a driving shaft. The driving motor used in the environmentally friendly vehicle is supplied with three-phase alternating current through an inverter. The inverter converts direct current of a battery into three-phase alternating current through a power module. At this time, the three-phase voltage is not a complete sinusoidal waveform, and the sum of the three-phase voltages is not zero. This is called a common-mode voltage. Due to the common-mode voltage applied to the coil of the driving motor, an axial voltage is generated in the rotating shaft due to a parasitic capacitance inside the driving motor. The axial voltage causes a potential difference between the inner and outer rings of a bearing that supports the rotating shaft, and causes electrical corrosion of the bearing through a discharge mechanism inside the bearing. Such electrical corrosion seriously affects the durability of the driving motor, for example, the electrical corrosion can damage the bearing or the like.

[0005] In the conventional art, in order to reduce the axial voltage generated on the rotating shaft of the driving motor, a grounding ring (shaft grounding ring) that applies current to both the housing and the rotating shaft is installed between the rotating shaft and the housing. However, the grounding ring provides electrical grounding connection of the rotating shaft that is rotating and the housing that is fixed. Therefore, friction is generated between the grounding ring and the rotating shaft, and the durability of the grounding ring is deteriorated due to the generated friction. In addition, the brush applied to the grounding ring has a disadvantage that the brush is low in oil resistance, and thus is easily damaged by automatic transmission fluid (ATF) oil. In addition, the grounding ring has a disadvantage that it is expensive.

[0006] The above statements are merely intended to help understand the background of the present invention, and do not mean that the present invention falls within the scope of prior art known to those skilled in the art. SUMMARY

[0007] The present invention provides a grounding structure of a driving motor for achieving application of current between a rotating shaft and a motor housing while reducing or minimizing friction with the rotating shaft.

[0008] In addition, the present application provides a grounding structure of a driving motor configured to prevent damage to the grounding structure due to rotation of a rotating shaft.

[0009] In one embodiment of the present application, a grounding structure of a driving motor applied to an environmentally friendly vehicle is provided, the driving motor including a rotating shaft rotatably supported by a bearing, a motor housing enveloping the bearing and the rotating shaft, a grounding structure disposed in a direction in which the rotating shaft extends, and a cover mounting the grounding structure therein and connected to the motor housing, wherein the grounding structure is in contact with the rotating shaft through a grounding unit, thereby grounding the rotating shaft.

[0010] In one embodiment, the grounding structure can include a grounding housing connected to the cover, a grounding unit extending from an inside of the grounding housing and in contact with the rotating shaft, and a spring fixedly coupled inside the grounding housing and electrically connected to the grounding unit.

[0011] In one embodiment, the grounding structure can further include a grounding plate disposed between the grounding unit and the spring, wherein the grounding unit is configured to rotate according to rotation of the rotating shaft, the grounding plate is in contact with the grounding unit, and functions to prevent damage to the spring due to rotation of the grounding unit.

[0012] In one embodiment, the grounding plate can reduce a rotational force transmitted to the spring due to sliding of a rotating body of the grounding unit.

[0013] In one embodiment, the grounding unit can include an extension portion extending toward the rotating shaft in the grounding housing, thereby being in contact with the rotating shaft, and a support portion preventing the grounding unit from being detached outward from the grounding housing and being in contact with the grounding plate.

[0014] In one embodiment, the grounding housing can have an opening in which one end of the grounding housing is open in a direction toward the rotating shaft, and a cross-sectional area of the support portion can be greater than an opening area of the opening, to prevent the grounding unit from being detached outward from the grounding housing.

[0015] In one embodiment, the support portion can be divided into a first region adjacent to the extension portion and a second region adjacent to the grounding plate, wherein the second region can be configured in a shape in which a cross-sectional area thereof decreases in a direction toward the grounding plate.

[0016] In one embodiment, the grounding housing can have an opening in which one end of the grounding housing is open in a direction toward the rotating shaft, and the grounding unit can be configured in a spherical shape having a diameter greater than a diameter of an opening area of the opening.

[0017] In one embodiment, the grounding structure can include a grounding case coupled to the cover, a grounding unit in contact with the rotating shaft and extending into the grounding case, a grounding plate electrically coupled to the grounding unit, and a spring fixedly coupled inside the grounding case and coupled to the grounding plate, wherein the grounding unit can include a grounding cover covering one end of the rotating shaft and an extension part extending from the grounding cover toward the grounding case.

[0018] In one embodiment, the grounding structure can further include an additional grounding plate disposed between the grounding unit and the grounding plate to prevent the spring from being damaged due to rotation of the rotating shaft.

[0019] In one embodiment, a cross-sectional area of the grounding unit can be smaller than a cross-sectional area of the rotating shaft.

[0020] In one embodiment, the grounding structure can be arranged to penetrate the cover, the grounding unit can be arranged inside the motor case, and an end of the grounding structure arranged in a direction opposite to the grounding unit can be arranged outside the motor case.

[0021] In one embodiment, the grounding unit can be in contact with a center of the rotating shaft.

[0022] According to embodiments of the present invention, since a grounding unit having a smaller cross-sectional area than a rotating shaft is used, an area in which the grounding unit and the rotating shaft cause friction can be reduced or minimized. Accordingly, when friction between the rotating shaft and the grounding unit is reduced, durability of a grounding structure including the grounding unit can be improved.

[0023] According to embodiments of the present invention, the grounding unit and the rotating shaft can be prevented from being damaged by a spring and a grounding plate constituting the grounding structure.

[0024] According to embodiments of the present invention, since an extension part of the grounding structure is in contact with a center of the rotating shaft, an area in which the grounding structure and the rotating shaft are in contact with each other can be reduced or minimized. Accordingly, durability of the grounding structure can be improved.

[0025] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific embodiments are intended for purposes of illustration only and are not intended to limit the scope of the present invention. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order for the present application to be better understood, various embodiments thereof will be described in detail by way of example with reference to the accompanying drawings, in which:

[0027] Figure 1is a schematic diagram showing a driving motor according to an embodiment of the present application;

[0028] Figure 2 is an exploded perspective view showing a grounding structure of a driving motor according to an embodiment of the present application;

[0029] Figure 3 is a schematic diagram showing a grounding structure of a driving motor grounding a rotating shaft according to an embodiment of the present application;

[0030] Figure 4 is a schematic diagram showing a grounding structure of a driving motor grounding a rotating shaft according to an embodiment of the present application;

[0031] Figure 5 is a schematic diagram showing a grounding structure of a driving motor grounding a rotating shaft according to an embodiment of the present application;

[0032] Figure 6 is a schematic diagram showing a grounding structure of a driving motor grounding a rotating shaft according to an embodiment of the present application;

[0033] Figure 7 is a schematic diagram showing a grounding structure of a driving motor grounding a rotating shaft according to an embodiment of the present application;

[0034] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the principles of the application. In the drawings: DETAILED DESCRIPTION

[0035] The following description is merely exemplary in nature and is not intended to limit the present application, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

[0036] Advantages and features of the present application and methods of accomplishing the same can be understood more readily by reference to the following detailed description of exemplary embodiments and the accompanying drawings. The present application may, however, be embodied in various different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the application to those skilled in the art, and no limitation of the scope of the application is intended by reference to the specific embodiments recited. In this regard, the description herein is merely exemplary in nature and is not intended to limit the present application, application, or uses. Throughout the specification, like reference numerals refer to like elements or features in various figures and embodiments of the application.

[0037] In the specification, terms such as “… part”, “… unit”, “… module” refer to a unit processing at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software.

[0038] Also, in the present specification, when components have the same names, the names of the components are classified as first, second, and so on to distinguish the components, but the names are not necessarily limited to the order in the following description.

[0039] The detailed description is intended to illustrate the present application. Also, the above description is to describe exemplary embodiments of the present application, and the present application can be used in various other combinations, modifications, and environments. That is, within the scope of the concept of the present application disclosed herein, the range equivalent to the disclosed disclosure, and / or the range of the art or the knowledge of the art, changes or modifications can be made. The described embodiments describe the best state for implementing the technical spirit of the present application, and various changes required in specific application fields and uses of the present application can be applied.

[0040] Therefore, the above detailed description of the present application is not intended to limit the present application to the disclosed embodiments. Also, the appended claims should be interpreted to include other embodiments.

[0041] Figure 1 is a schematic view showing a driving motor according to an embodiment of the present application.

[0042] Reference Figure 1 The driving motor 1 can include a stator (not shown) fixedly installed inside the motor housing 10 and generating a magnetic flux, and a rotor (not shown) arranged to be spaced apart from the stator and rotating around a rotation shaft 200 as a driving shaft. For example, the driving motor 1 can be applied to a synchronous motor of an inner rotor type in which the rotor (not shown) is arranged at the inner side of the stator (not shown).

[0043] A cover 15 for sealing the housing 10 can be installed at one side of the housing 10. Also, the cover 15 can be connected to the housing 10. The rotation shaft 200 can be rotatably supported by a bearing 300 arranged at one side of the housing 10.

[0044] The cover 15 can be provided with a grounding structure 100 for applying an electric current between the rotation shaft 200 and the housing 10. The grounding structure 100 can be made of an electrically conductive material. The grounding structure 100 can be arranged to penetrate the cover 15. The grounding structure 100 can move an electric charge (the electric charge causing an axial voltage generated in the rotation shaft 200) to the housing 10 by directly contacting the rotation shaft 200. That is, the grounding structure 100 can be in contact with the rotation shaft 200 through a grounding unit 130 as one component of the grounding structure 100, so that the rotation shaft 200 is grounded. The grounding unit 130 can be arranged inside the housing 10, and one end of the grounding structure 100 arranged in the opposite direction of the grounding unit 130 can be arranged outside the housing 10.

[0045] The cross-sectional area of the grounding unit 130 can be smaller than that of the rotating shaft 200. In addition, the grounding unit 130 can be disposed at a position corresponding to the rotational axis of the rotating shaft 200 to be in contact with the center of the rotating shaft 200. In this way, the area in which the grounding unit 130 and the rotating shaft 200 come into contact with each other can be reduced or minimized.

[0046] In general, a grounding ring applied to the driving motor 1 is in contact with the outer surface of the rotating shaft 200. Accordingly, the grounding ring and the rotating shaft 200 generate friction on an area equal to the product of the circumference with reference to the rotational axis of the rotating shaft 200 and the width of the grounding ring in the direction of the rotational axis. However, according to one embodiment of the present application, the grounding unit 130 is configured to have a smaller cross-sectional area than the rotating shaft 200, and thus the grounding unit 130 and the rotating shaft 200 can cause friction only in an area corresponding to the cross-sectional area of the grounding unit 130. In summary, when the friction between the rotating shaft 200 and the grounding unit 130 is reduced, the durability of the grounding structure 100 including the grounding unit 130 can be improved.

[0047] Figure 2 FIG. 1 is an exploded perspective view showing a grounding structure of a driving motor according to one embodiment of the present application, Figure 3 FIG. 2 is a schematic view showing a grounding structure of a driving motor in which a rotating shaft is grounded according to one embodiment of the present application.

[0048] Reference Figures 1 to 3 The grounding structure 100 can include a grounding case 110, a grounding unit 130, a spring 150, and a grounding plate 170.

[0049] The grounding case 110 is configured to be in contact with the cover 15, and can be divided into a first grounding case 111 and a second grounding case 113. The first grounding case 111 and the second grounding case 113 can be provided with a hollow portion for disposing the grounding unit 130, the spring 150, and the grounding plate 170. The first grounding case 111 can be configured to be in direct contact with the cover 15. The second grounding case 113 can be inserted into the hollow portion of the first grounding case 111. In the second grounding case 113, an opening 115, which is a passage through which the grounding unit 130 extends to the outside of the grounding structure 100, can be defined. The opening 115 can mean a region in which one end of the second grounding case 113 is open in a direction in which the second grounding case 113 faces the rotating shaft 200.

[0050] The grounding unit 130 can be configured to extend from the inside of the grounding housing 110 and contact the rotating shaft 200. The grounding unit 130 can include an extension portion 131 extending from the inside of the grounding housing 110 toward the rotating shaft 200 so as to directly contact the rotating shaft 200, and support portions 133 and 135 for preventing the grounding unit 130 from being detached outward from the grounding housing 110.

[0051] The extension portion 131 can have a pin shape extending toward the opening 115 defined in the second grounding housing 113. The support portions 133 and 135 can be connected to the extension portion 131. The support portions 133 and 135 can be electrically connected to the grounding plate 170. The support portions 133 and 135 can be configured not to be always physically connected to the grounding plate 170. However, by the movement of the spring 150, the support portions 133 and 135 can come into contact with the grounding plate 170, and the support portions 133 and 135 can transfer the electric charge transferred from the extension portion 131 to the spring 150 and / or the grounding housing 110. The cross-sectional area of the support portions 133 and 135 can be greater than the opening area of the opening 115. Since the cross-sectional area of the support portions 133 and 135 is greater than the opening area of the opening 115, the grounding unit 130 can be prevented from being detached outward from the grounding housing 110. The opening area can refer to the area of the hole provided by the opening 115 in the second grounding housing 113.

[0052] The support portions 133 and 135 can be divided into a first region 133 connected to the extension portion 131 and a second region 135 adjacent to the grounding plate 170. The second region 135 can denote a region in contact with the grounding plate 170. The first region 133 and the second region 135 can have different cross-sectional areas from each other, which are cut in a direction perpendicular to the rotating axis. The second region 135 can have a shape in which the cross-sectional area thereof gradually decreases in a direction toward the grounding plate 170. For example, the second region 135 can have a conical shape. Unlike the above-described example, the second region 135 can have the same cross-sectional area as the first region 133, and the second region 135 can have a smaller cross-sectional area than the first region 133.

[0053] The spring 150 is fixedly coupled inside the first grounding housing 111 to be electrically connected to the grounding unit 130 and the grounding plate 170. In the present embodiment, the spring 150 can be connected to the grounding plate 170. The spring 150 can change the position of the grounding unit 130 to prevent the grounding unit 130 from being damaged due to friction with the rotating shaft 200. For example, when the spring 150 is contracted, the grounding unit 130 can not be in contact with the rotating shaft 200. In addition, due to the elasticity of the spring 150, the grounding unit 130 and the rotating shaft 200 can not be in strong contact with each other, and thus the durability of the grounding unit 130 and the rotating shaft 200 can be improved.

[0054] The grounding plate 170 can be disposed between the grounding unit 130 and the spring 150. The grounding plate 170 is connected to the spring 150, but can not always be connected to the grounding unit 130. However, when the grounding plate 170 and the grounding unit 130 are connected to each other, the rotating shaft 200 can be grounded. Although the grounding plate 170 is not configured to be physically connected to the grounding unit 130, the grounding plate 170 and the grounding unit 130 can always be in contact with each other. When the grounding unit 130 is in contact with the rotating shaft 200, the grounding unit 130 can rotate in the same direction as the rotating shaft 200. However, due to a sliding phenomenon generated between the grounding unit 130 and the rotating shaft 200, the grounding unit 130 can rotate at a lower rotational speed than the rotating shaft 200. In addition, slippage can also occur between the grounding plate 170 and the grounding unit 130, and the grounding plate 170 can rotate at a lower rotational speed than the grounding unit 130. Accordingly, the grounding plate 170 can minimize the rotational force of the rotating shaft 200 transmitted to the spring 150, and thus the grounding plate 170 can prevent the spring 150 from being damaged due to the rotation of the grounding unit 130. That is, the grounding plate 170 can reduce the rotational force transmitted to the spring 150 through the sliding of the rotating body of the grounding unit 130 and the sliding of the grounding plate 170 itself.

[0055] According to one embodiment of the present application, since the area in which the grounding structure 100 and the rotating shaft 200 are in contact with each other is reduced or minimized, the durability of the grounding structure 100 can be improved. In addition, by the spring 150 and the grounding plate 170 of the grounding structure 100, the grounding unit 130 and the rotating shaft 200 can be prevented from being damaged.

[0056] According to another embodiment of the present application, when the extension portion 131 of the grounding structure 100 is in contact with the center of the rotating shaft 200, the area in which the grounding structure 100 and the rotating shaft 200 are in contact with each other can be reduced or minimized. Accordingly, the durability of the grounding structure 100 can be improved.

[0057] Figure 4 is a view showing a grounding structure of a driving motor that grounds a rotating shaft according to one embodiment of the present application. For simplicity, the description of the contents repeated in Figure 3 is omitted.

[0058] Referring to Figure 4 , the grounding structure 100 can include the grounding unit 130 and the spring 150. In comparison with Figure 3 , Figure 4 the grounding structure 100 of the driving motor according to one embodiment of the present application can have a structure in which the grounding plate 170 is omitted. Accordingly, the grounding structure 100 can be manufactured with a simple structure, and thus the cost of producing the grounding structure 100 can be reduced.

[0059] The ground unit 130 can be directly connected with the spring 150. Accordingly, the rotational force of the rotational shaft 200 can be relatively greatly transmitted to the spring 150.

[0060] Figure 5 FIG. 1 is a schematic view showing a ground structure of a driving motor grounding a rotational shaft according to an embodiment of the present application. Figure 3 Description of repeated content is omitted.

[0061] Referring to Figure 5 , the ground structure 100 can have a spherical ground unit 135. A portion of the ground unit 135 can be exposed through the opening 115, and the exposed portion of the ground unit 135 can be in contact with the rotational shaft 200. At this time, the ground unit 135 can be in contact with the center of the rotational shaft 200. For example, the opening 115 can have a circular opening area, and the diameter of the opening area can be smaller than the diameter of the spherical ground unit 135. Accordingly, the ground unit 135 can be prohibited or prevented from being detached outward from the ground housing 110. In addition, since the ground unit 135 has a spherical shape, the possibility that the ground unit 135 is damaged due to friction with the rotational shaft 200 can be reduced. In addition, since the ground unit 135 has a spherical shape, the ground unit 135 and the rotational shaft 200 can be in point contact with each other. For example, according to an embodiment of the present application, the area in which the ground unit 135 and the rotational shaft 200 are in contact with each other can be reduced compared to the embodiments of the Figure 5 Figure 3 and Figure 4 . The ground unit 135 can be electrically connected to the ground plate 170, and the ground plate 170 can be connected to the spring 150. The ground unit 135, the spring 150, and the ground plate 170 can be disposed inside the ground housing 110, and the ground unit 135 can be exposed only a portion thereof outside the ground housing 110.

[0062] Figure 6 FIG. 1 is a schematic view showing a ground structure of a driving motor grounding a rotational shaft according to an embodiment of the present application.

[0063] Referring to Figure 6 , the ground structure 100 can include a ground unit 140 including a ground cover 141 covering one end of the rotational shaft 200 and an extension portion 143 extending from the ground cover 141 toward the ground housing 110. The ground cover 141 can cover the end of the cylindrical rotational shaft 200. The extension portion 143 can be connected to the ground cover 141, and the extension portion 143 can be disposed at a position coinciding with the rotational axis and extend in a direction coinciding with the rotational axis. The extension portion 143 can rotate at the same rotational speed as the rotational shaft 200.

[0064] ​The extension portion 143 can be in contact with the grounding plate 170. The cross-sectional area of the extension portion 143 in a direction perpendicular to the rotation axis can be smaller than that of the grounding plate 170. Accordingly, the friction area causing friction with the grounding plate 170 can be determined according to the degree of the cross-sectional area of the extension portion 143. The slippage phenomenon can occur between the extension portion 143 and the grounding plate 170, and thus the rotational force of the extension portion 143 transmitted to the spring 150 can be reduced. Accordingly, the spring 150 can be prevented from being damaged due to the rotational force of the rotation shaft 200.

[0065] Figure 7 is a schematic view showing a grounding structure of a driving motor grounding a rotation shaft according to an embodiment of the present application. For simplicity, descriptions of contents repeated with Figure 6

[0066] Referring to Figure 7 , the grounding structure 100 can include a grounding unit 140 including a grounding cover 141 and an extension portion 143, a spring 150 fixedly coupled to the grounding housing 110, a grounding plate 170 in contact with the spring 150, and an additional grounding plate 175 disposed between the grounding plate 170 and the grounding unit 140. The additional grounding plate 175 can be provided to prevent the spring 150 from being damaged due to the rotational force of the rotation shaft 200. In contrast to Figure 6 , since two grounding plates 170 and 175 are provided between the grounding unit 140 and the spring 150, the rotational force of the rotation shaft 200 transmitted to the spring 150 can be reduced or minimized. Accordingly, the possibility of damaging the spring 150 can be reduced, and thus the durability of the grounding structure 100 can be improved.

[0067] Embodiments of the present application have been described above with reference to the accompanying drawings, but it will be understood by those skilled in the art related to the present application that the present application can be implemented in other specific embodiments without changing the technical spirit or essential characteristics thereof. Therefore, it should be understood that the above-described embodiments are illustrative in all aspects and are not restrictive.​

Claims

1. A grounding structure of a drive motor, the drive motor being applied to an eco-friendly vehicle, the drive motor comprising: a rotating shaft rotatably supported by a bearing; a motor housing surrounding the bearing and the rotating shaft; the grounding structure disposed in a direction in which the rotating shaft extends; and a cover in which the grounding structure is installed, the cover being connected to the motor housing, wherein the grounding structure is configured to contact the rotating shaft by a grounding unit, thereby grounding the rotating shaft, wherein the grounding structure comprises: a grounding housing connected to the cover, wherein the grounding unit extends from an inside of the grounding housing and is configured to contact the rotating shaft; a spring fixedly coupled inside the grounding housing and electrically connected to the grounding unit; and a grounding plate disposed between the grounding unit and the spring, wherein the grounding unit is configured to rotate only in a same direction as a rotational axis of the rotating shaft, the grounding plate is configured to contact the grounding unit and prevent the spring from being damaged due to rotation of the grounding unit. the grounding plate is configured to reduce a rotational force transmitted to the spring due to sliding of a rotating body of the grounding unit.

2. The ground structure of a drive motor according to claim 1, wherein, the grounding unit comprises:

3. The ground structure of a drive motor according to claim 1, wherein, an extension portion extending in the grounding housing toward the rotating shaft, thereby contacting the rotating shaft; and a support portion configured to prohibit the grounding unit from being outwardly detached from the grounding housing and to contact the grounding plate. 4.The grounding structure of the drive motor according to claim 3, wherein: the grounding housing has an opening in which one end of the grounding housing is open in a direction toward the rotating shaft, a cross-sectional area of the support portion is greater than an opening area of the opening to prevent the grounding unit from being outwardly detached from the grounding housing. 5.The grounding structure of the drive motor according to claim 3, wherein: the support portion is divided into a first region adjacent to the extension portion and a second region adjacent to the grounding plate, the second region includes a cross-sectional area that decreases in a direction toward the grounding plate. 6.The grounding structure of the drive motor according to claim 1, wherein: the grounding housing has an opening in which one end of the grounding housing is open in a direction toward the rotating shaft, the grounding unit is configured in a ball type having a diameter greater than a diameter of an opening area of the opening. the grounding structure comprises:

7. The ground structure of a drive motor according to claim 1, wherein, a grounding housing connected to the cover; the grounding unit configured to contact the rotating shaft and to extend into the grounding housing; a grounding plate electrically connected to the grounding unit; and a spring fixedly coupled inside the grounding housing and connected to the grounding plate, wherein the grounding unit includes a grounding cover covering one end of the rotating shaft and an extension portion extending from the grounding cover toward the grounding housing. the grounding structure further comprises an additional grounding plate disposed between the grounding unit and the grounding plate to prevent the spring from being damaged due to rotation of the rotating shaft.

8. The ground structure of a drive motor according to claim 7, wherein, a cross-sectional area of the grounding unit is less than a cross-sectional area of the rotating shaft.

9. The ground structure of a drive motor according to claim 1, wherein, 10.The grounding structure of the drive motor according to claim 1, wherein: the grounding structure is disposed to penetrate the cover, the grounding unit is disposed inside the motor housing, ​ The ground structure is arranged at one end in the direction opposite to the ground unit outside the motor housing.

11. The ground structure of a drive motor according to claim 1, wherein, The ground unit is configured to contact the center of the rotating shaft.

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