Shaft ground ring to prevent bearing corrosion

Abstract

A shaft ground ring and an assembly thereof are disclosed. According to the present invention, there is provided a shaft ground ring that is fastened to the shaft of an electric motor to prevent electrolytic corrosion caused by leakage current, and includes a ring body that extends to surround the outer circumferential surface of the shaft, and a plurality of ground protrusions that protrude from the inner circumferential surface of the ring body and contact the outer circumferential surface of the shaft, the plurality of ground protrusions being spaced apart with a predetermined gap along the ring body. The present invention maintains a proper grounding state in an oil-cooled environment and can function properly even in a high-capacity electric motor.

Description

[Technical field]

[0001] The present invention relates to a shaft ground ring that prevents electrical corrosion of bearings due to leakage current. [Background technology]

[0002] With the electrification of vehicles, existing internal combustion engines are being replaced by electric motors. As electric motors become the main driving source, problems due to electrical erosion of bearings have come to light. Bearing erosion is a phenomenon in which leakage current from an electric motor flows along the shaft, generating sparks and damaging the bearing surface. Bearing erosion can cause damage to the bearing itself and shorten its lifespan, and can even lead to damage to electric motors, reducers, etc. due to bearing breakage. In particular, as electric motors become the main driving source, the operating voltage is continually increasing to improve performance, which is a factor that further promotes bearing erosion.

[0003] A shaft ground ring is known as one of the means for preventing bearing electrolytic corrosion. The shaft ground ring is a means for reducing bearing electrolytic corrosion by directing the current flowing along the shaft to the outside through the housing.

[0004] Shaft ground rings used in dry environments are known to be of the pad type or brush type, mainly made of carbon. As an example, Korean Patent Publication No. 10-2314718 discloses a brush-type "bearing electrolytic corrosion prevention device."

[0005] However, conventional shaft ground rings designed for dry environments have the disadvantage that they do not function properly in vehicle electric motors, which are becoming increasingly powerful. Specifically, pad-type ground rings used in dry environments must come into close contact with the shaft to deal with unbalancing of the electric motor, which can cause relatively large friction at the contact points and lead to wear problems due to friction. As a result, they are not suitable for large-capacity electric motors used as main driving sources. In addition, pad-type ground rings have the disadvantage that it is difficult to deal with poor contact because they come into contact at a single point.

[0006] The brush type using carbon fiber was developed to solve the problems of friction and poor contact that the pad type has. However, although the brush type can function properly in a dry environment, in large-capacity electric motors that use an oil cooling method, the brush fiber is coated with oil, which causes a problem of reduced insulation performance.

[0007] Meanwhile, electric motors used as driving sources for vehicles have recently adopted an oil cooling method that uses oil as a cooling medium due to the high operating voltage. As a result, shaft ground rings designed for conventional dry environments are being supplemented with various methods. As an example, Korean Patent Publication No. 10-2019-0050559 discloses a "ground ring mounting structure for drive motor" that uses cooling oil. The above-mentioned published patent focuses on the problem of oil flowing to both ends of the shaft flowing into the ground ring (shaft ground ring) and reducing the grounding performance of the ground ring, and prevents the flow of oil into the ground ring through a blocking unit. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent No. 10-2314718 [Patent Document 2] Korean Patent Publication No. 10-2019-0050559 Summary of the Invention [Problem to be solved by the invention]

[0009] SUMMARY OF THE PRESENT EMBODIMENTS The present invention seeks to provide a shaft ground ring and assembly therefor that can prevent electrical corrosion of bearings due to leakage currents.

[0010] Additionally, embodiments of the present invention seek to provide a shaft ground ring and assembly therefor that maintains proper grounding in an oil cooled environment and can function properly with high capacity electric motors.

[0011] However, the technical problems to be achieved by the embodiments of the present invention are not necessarily limited to the technical problems mentioned above. Other technical problems not mentioned will be clearly understood by those having ordinary skill in the art to which the embodiments of the present invention pertain from other descriptions in the specification, such as the detailed description. [Means for solving the problem]

[0012] According to a first aspect of the present invention, there may be provided a shaft ground ring that is fastened to a shaft of an electric motor to prevent electrolytic corrosion due to leakage current, the shaft ground ring including: a ring body extending to surround an outer circumferential surface of the shaft; and ground protrusions protruding from an inner circumferential surface of the ring body to contact the outer circumferential surface of the shaft, the ground protrusions being spaced apart with a predetermined gap along the ring body.

[0013] According to a second aspect of the present invention, there may be provided a shaft ground ring assembly including: the shaft ground ring; and a housing fastened to receive the shaft ground ring therein.

[0014] According to a third aspect of the present invention, there may be provided a shaft ground ring including: a shaft ground ring fastened to a shaft of an electric motor to prevent electrolytic corrosion due to leakage current; and a housing fastened to the shaft to support the shaft ground ring at an outer circumferential portion of the shaft; the shaft ground ring including a plurality of ground protrusions formed to protrude from an outer circumferential surface of the shaft ground ring and spaced apart from each other in a circumferential direction with a predetermined gap therebetween. Effect of the Invention

[0015] In the shaft ground ring and the assembly thereof according to the embodiment of the present invention, the ground protrusions come into contact with the shaft, and the leakage current flowing along the shaft can be discharged to the outside, thereby preventing electrolytic corrosion of the bearing.

[0016] In addition, the shaft ground ring and the assembly thereof according to the embodiment of the present invention may have flow passages in the front-rear or left-right direction while a plurality of contact points are maintained in contact. The first flow passage in the circumferential direction is connected to the outer circumferential surface of the shaft through a gap, and the second flow passage in the front-rear direction is directly connected to the outer circumferential surface of the shaft. Therefore, oil for cooling can be quickly discharged to the outside, and deterioration of insulation performance due to oil can be effectively prevented.

[0017] In addition, the shaft ground ring and assembly according to the present invention can better address misalignment and shaft imbalance during assembly by using a method of contacting the shaft at multiple contact points.

[0018] Furthermore, due to the above-mentioned characteristics, the shaft ground ring and assembly according to the embodiment of the present invention can maintain a proper grounding condition even in an oil-cooled environment where oil is used as a cooling medium, and can be adapted to be suitable for use in high-capacity electric motors.

[0019] However, the technical effects obtained through the embodiments of the present invention are not necessarily limited to the effects mentioned above. Other technical effects not mentioned will be clearly understood by those having ordinary skill in the art to which the present invention pertains from other descriptions in the specification, such as the detailed description. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a front perspective view of a shaft ground ring assembly according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a rear perspective view of the shaft ground ring assembly illustrated in FIG. 1. [Diagram 3] FIG. 2 is a cross-sectional view of the shaft ground ring assembly illustrated in FIG. 1. [Figure 4] 4A to 4C show first to third modified examples of the housing shown in FIG. [Diagram 5] FIG. 2 is a rear view of the shaft ground ring illustrated in FIG. 1. [Figure 6] FIG. 6 is an enlarged view of the ground protrusion shown in FIG. 5. [Figure 7] 6 is an enlarged view of the ground protrusion shown in FIG. 5, seen from another direction. [Figure 8] 7 is a first cross-sectional view of the ground protrusion shown in FIG. 6. [Figure 9] 7 is a second cross-sectional view of the ground protrusion shown in FIG. 6. [Figure 10] FIG. 10 is a diagram showing an installation state of the ground protrusion shown in FIG. 9; [Figure 11] FIG. 11 is a front perspective view of a shaft ground ring according to a second embodiment of the present invention. [Figure 12] FIG. 12 is an enlarged view of the shaft ground ring shown in FIG. [Figure 13] FIG. 10 is a partial cross-sectional perspective view of a shaft ground ring according to a third embodiment of the present invention. [Figure 14] FIG. 10 is a front view of a shaft ground ring assembly according to a fourth embodiment of the present invention. [Figure 15] FIG. 15 is a cross-sectional view of the shaft ground ring illustrated in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The following embodiments may be provided to more completely explain the present invention to those skilled in the art. However, the following embodiments are provided to aid in the understanding of the present invention, and the technical idea of ​​the present invention is not necessarily limited to the following embodiments. In addition, detailed descriptions of configurations that may obscure the technical gist of the present invention or are well known will be omitted.

[0022] Figure 1 is a front perspective view of a shaft ground ring assembly according to one embodiment of the present invention. Figure 2 is a rear perspective view of the shaft ground ring assembly shown in Figure 1.

[0023] 1 and 2, a shaft ground ring assembly 100 (hereinafter, referred to as "assembly 100") of this embodiment can be used to prevent electrical corrosion of a bearing caused by leakage current. The assembly 100 of this embodiment can function more appropriately in an oil cooling system that uses oil as a cooling medium. However, the assembly 100 of this embodiment is not necessarily limited to use in the oil cooling system.

[0024] The assembly 100 of this example may include a housing 110 and a shaft ground ring 120 .

[0025] The housing 110 and the shaft ground ring 120 may extend circumferentially around the outer periphery of the shaft 10. Illustratively, the housing 110 and the shaft ground ring 120 are generally annular in shape.

[0026] The shaft 10 may be formed to extend in a lengthwise direction. In this description, the lengthwise direction of the shaft 10 is referred to as the front-rear direction. The assembly 100 of this embodiment may be used in an electric motor for a vehicle, in which case the shaft 10 may be configured as a rotating shaft of the electric motor. However, this is not necessarily limited thereto. As an example, the assembly 100 of this embodiment may be used in a generator for a vehicle having a structure similar to that of an electric motor, in which case the shaft 10 may be configured as a rotating shaft of the generator.

[0027] The shaft ground ring 120 may be fastened to an inner periphery of the housing 110. The shaft ground ring 120 may be supported by the housing 110 through a predetermined coupling structure.

[0028] The shaft ground ring 120 may have an inner end disposed toward the central axis S1 of the shaft 10. The inner end of the shaft ground ring 120 may be supported in contact with the outer surface of the shaft 10. This allows leakage current flowing along the shaft 10 to be discharged to the outside of the housing, etc., through the shaft ground ring 120.

[0029] The shaft ground ring 120 may include a number of ground prongs 122 .

[0030] The ground protrusion 122 may be formed to extend a predetermined distance from the inner circumferential portion of the shaft ground ring 120 toward the central axis S1. The ground protrusion 122 is intended to be in direct contact with the outer surface of the shaft 10.

[0031] A plurality of ground protrusions 122 may be provided. The plurality of ground protrusions 122 may be arranged in a circumferential direction along an inner circumferential portion of the shaft ground ring 120. A predetermined gap G1 may be formed between the ground protrusions 122 arranged adjacent to each other in the circumferential direction.

[0032] The shaft ground ring 120 may be formed of a unitary piece with the plurality of ground prongs 122. That is, the plurality of ground prongs 122 may be integrally formed with the shaft ground ring 120.

[0033] The shaft ground ring 120 may be partially or entirely made of a plastic material. Preferably, the shaft ground ring 120 may be entirely made of a plastic material. Or, the shaft ground ring 120 may be partially or entirely made of a conductive plastic material. Preferably, the shaft ground ring 120 may be entirely made of a conductive plastic material. As an example, the shaft ground ring 120 may be partially or entirely made of a conductive plastic material containing a metal or a carbon-based filler such as carbon black, carbon fiber, or carbon nano tube.

[0034] Figure 3 is a cross-sectional view of the shaft ground ring assembly shown in Figure 1. Figure 3 illustrates a cross-section along line C1-C1 indicated in Figure 1.

[0035] Referring to FIG. 3, the housing 110 of this embodiment may include a housing body 111 .

[0036] The housing body 111 may have a predetermined cross section and may be formed to extend in a circumferential direction so as to correspond to the outer circumferential surface of the shaft 10 .

[0037] The housing body 111 may have a ring support surface 111a on its inner surface facing the shaft 10. The shaft ground ring 120 and the housing cover 112 described below may be contacted and supported on the ring support surface 111a. The ring support surface 111a may be extended a predetermined width in the front-rear direction to correspond to the thickness of the shaft ground ring 120 and the housing cover 112.

[0038] A swaging 111b may be formed behind the ring support surface 111a. The swaging 111b may be formed with an inclination so as to approach the central axis S1 of the shaft 10 as it goes rearward. The swaging 111b may support the rearward removal of the housing cover 112. This allows the shaft ground ring 120 to be properly supported between the housing body 111 and the housing cover 112.

[0039] A part or the whole of the housing 110 including the swaging 111b may be made of an elastic material, so that the housing cover 112 may be assembled to or separated from the ring support surface 111a through appropriate elastic deformation of the housing 110 or the swaging 111b.

[0040] Meanwhile, the housing 110 of this embodiment may include a housing cover 112 .

[0041] The housing cover 112 may be formed to extend in a circumferential direction so as to correspond to the housing body 111. The housing cover 112 may have a generally annular shape.

[0042] The housing cover 112 may have a radially outer peripheral surface fastened to the ring support surface 111a. The housing cover 112 may be suitably secured between the rear surface of the shaft ground ring 120 and the swaging 111b.

[0043] FIG. 4 shows first to third modified examples of the housing shown in FIG.

[0044] FIG. 4(a) illustrates a housing 110-1 according to a first modified example.

[0045] Referring to FIG. 4(a), a housing 110-1 of this modified example can include a housing main body 111-1.

[0046] The housing body 111-1 corresponds to the housing body 111 of the above-described embodiment. The housing body 111-1 of this modification may be formed to be generally similar to the housing body 111 of the above-described embodiment. That is, the housing body 111-1 may include a ring support surface 111a-1 on which the shaft ground ring 120 is contacted and supported.

[0047] However, the housing body 111-1 of this modification may omit the swaging 111b of the above-described embodiment, and the swaging 111b may be replaced by a fastening member 111c-1.

[0048] Specifically, the housing body 111-1, the shaft ground ring 120, and the housing cover 112-1 may each have a fastening hole formed in the front-rear direction. The fastening member 111c-1 may be inserted from the housing cover 112-1 side and inserted into the fastening hole of the housing body 111-1 through the shaft ground ring 120 and fastened. The shaft ground ring 120 may be fixedly installed between the housing cover 112-1 and the housing body 111-1 by the fastening member 111c-1.

[0049] The fastening member 111c-1 may include various types of fastening means known in the art. For example, the fastening member 111c-1 may be a bolt that is screwed into a fastening hole.

[0050] Meanwhile, the housing 110-1 of this modification may include a housing cover 112-1.

[0051] The housing cover 112-1 may be formed to be substantially the same as or similar to the housing cover 112 of the above-described embodiment, except for the fastening holes for fastening the fastening members 111c-1.

[0052] FIG. 4(b) illustrates a housing 110-2 according to a second modified example.

[0053] 4(b), the housing 110-2 of this modification may include a housing body 111-2 and a housing cover 112-2, and the housing body 111-2 and the housing cover 112-2 may be fastened by a fastening member 112c-2 sandwiching the shaft ground ring 120. This modification has some differences in the form of the fastening member 111c-2 compared to the first modification described above.

[0054] FIG. 4(c) illustrates a housing 110-3 according to a third modified example.

[0055] 4(c), the housing 100-3 of this modified example may include a housing body 111-3. The housing body 111-3 may have a fastening hole for fastening the fastening member 111c-3. The housing body 111-3 of this modified example may be formed to be substantially the same as or similar to the modified example described above.

[0056] However, in the case of this modification, the housing covers 112-1 and 112-2 of the above-described modification may be omitted. In this modification, the functions of the housing covers 112-1 and 112-2 may be replaced by a fastening member 111c-3.

[0057] Meanwhile, the housing 110-3 of this modified example may include a fastening member 111c-3. The fastening member 111c-3 may be fastened to the shaft ground ring 120 and the housing body 111-3 to fix the shaft ground ring 120 to the housing body 111-3.

[0058] In this modification, the fastening member 111c-3 can have both the functions of the housing covers 112-1 and 112-2 of the modification described above. Specifically, the fastening member 111c-3 can be formed in a form in which one end is supported in contact with the housing main body 111-3 and the opposite end is supported in contact with the shaft ground ring 120, and the housing main body 111-3 and the shaft ground ring 120 are compressed and fixed together. As an example, the fastening member 111c-3 of this modification can be formed of a rivet having heads on both ends.

[0059] FIG. 5 is a rear view of the shaft ground ring illustrated in FIG.

[0060] 5, the shaft ground ring 120 may be formed in a generally circular ring shape. The shaft ground ring 120 may be disposed between the housing body 111 and the housing cover 112 and fixed to the housing 110.

[0061] The shaft ground ring 120 of this embodiment may include a ring body 121 .

[0062] The ring body 121 may have a predetermined cross-sectional shape and may be formed to have an elongated ring shape. In this embodiment, it is assumed that the ring body 121 has a substantially rectangular cross-sectional shape (see FIG. 3).

[0063] Meanwhile, the shaft ground ring 120 of this embodiment may include a plurality of ground protrusions 122 .

[0064] The ground projection 122 may be formed to protrude from an inner circumferential portion of the ring body 121 toward the shaft 10. An end of the ground projection 122 may be disposed in contact with the outer surface of the shaft 10.

[0065] A plurality of ground protrusions 122 may be provided, and the plurality of ground protrusions 122 may be spaced apart from each other at a predetermined distance in the circumferential direction from the inner circumferential portion of the ring body 121. That is, the plurality of ground protrusions 122 may be spaced apart from each other in the circumferential direction based on the central axis S1 in the front-rear direction. This allows the shaft 10 to appropriately contact the ground protrusions 122 over the entire circumferential area.

[0066] A gap G1 may be formed between the circumferentially adjacent ground protrusions 122. The gap G1 may be defined as an empty space between the circumferentially adjacent ground protrusions 122. The gap G1 may provide a flow path in the front-rear direction between the circumferentially adjacent ground protrusions 122. This allows oil or the like present on the outer surface of the shaft 10 to flow forward and backward through the gap G1.

[0067] In this embodiment, a total of 16 ground projections 122 are illustrated, and the gap G1 is illustrated as being formed to be approximately a predetermined amount smaller than the circumferential width of the ground projections 122. However, the number of ground projections 122 and the width of the gap G1 are not necessarily limited to those illustrated.

[0068] Meanwhile, the shaft ground ring 120 may be fastened to an outer periphery of the shaft 10. Specifically, the shaft ground ring 120 may be fastened to the shaft 10 in a form in which a plurality of ground protrusions 122 contact the outer periphery of the shaft 10.

[0069] In an initial state, a first radius R1 formed by the ground protrusions 122 may be formed slightly smaller than a second radius R2 formed by the outer circumferential surface of the shaft 10. Here, the initial state refers to a state before the shaft ground ring 120 is installed on the shaft 10 and no separate external force is applied. Also, the first radius R1 refers to the radius of an imaginary circle connecting the ends of the ground protrusions 122 toward the central axis S1.

[0070] In this case, the ground protrusions 122 may be elastically deformed to a certain degree from an initial state having a first radius R1 to be fastened to the shaft 10 having a second radius R2.

[0071] FIG. 6 is an enlarged view of the ground protrusion shown in FIG.

[0072] Referring to FIG. 6, the ground protrusion 122 may be formed to extend from the ring body 121 toward the central axis S1.

[0073] Here, first to fourth contact points 122a to 122d may be formed at the end of the ground protrusion 122 facing the central axis S1.

[0074] Specifically, the ground protrusion 122 may have first and second contact points 122a, 122b arranged on one side in the circumferential direction (the right side in the drawing) and third and fourth contact points 122c, 122d arranged on the opposite side (the left side in the drawing). Although not clearly shown in FIG. 5, the first and second contact points 122a, 122b may be spaced apart from each other in the front-rear direction along the direction of the central axis S1. Also, the third and fourth contact points 122c, 122d may be spaced apart from each other in the front-rear direction along the direction of the central axis S1 (see FIG. 7).

[0075] The first to fourth contact points 122a to 122d may be formed to protrude a predetermined amount from the end of the ground projection 122 toward the central axis S1. In an ideal installation state, the first to fourth contact points 122a to 122d are intended to come into contact with the outer circumferential surface of the shaft 10. That is, the ground projection 122 of this embodiment is intended to come into contact with the shaft 10 at four locations, the first to fourth contact points 122a to 122d, in an ideal installation state.

[0076] Meanwhile, the ground protrusion 122 may include a second flow passage 122e.

[0077] The second flow passage 122e may be formed between the first and second contact points 122a, 122b and the third and fourth contact points 122c, 122d. That is, the first to fourth contact points 122a to 122d may protrude in a predetermined shape at each position, so that the second flow passage 122e may be formed in a recessed shape between the first and second contact points 122a, 122b and the third and fourth contact points 122c, 122d. The second flow passage 122e may be formed to extend in the front-rear direction by the central axis S1.

[0078] 7 is an enlarged view of the ground protrusion shown in FIG 5 from another direction, and shows the ground protrusion from the C2 direction shown in FIG 5.

[0079] 7, the first and second contact points 122a, 122b and the third and fourth contact points 122c, 122d may be spaced apart from each other at a predetermined distance along the circumferential direction. Also, the first and fourth contact points 122a, 122d may be spaced apart from the second and third contact points 122b, 122c at a predetermined distance along the central axis S1. That is, the first and second contact points 122a, 122b may be spaced apart from each other at a predetermined distance on one side in the circumferential direction (the right side in the drawing), and the third and fourth contact points 122c, 122d may be spaced apart from each other at a predetermined distance on the opposite side (the left side in the drawing).

[0080] In this description, for convenience, the contact points 122b to 122d are named second to fourth contact points 122b to 122d in sequence in the clockwise direction with the first contact point 122a as a reference.

[0081] The second flow passage 122e may be formed to extend back and forth between the first contact point 122a and the fourth contact point 122d and between the second contact point 122b and the third contact point 122c.

[0082] Additionally, the ground protrusion 122 may include a first passage 122f.

[0083] The first flow passage 122f may be formed between the first and fourth contact points 122a, 122d and the second and third contact points 122b, 122c. That is, the first to fourth contact points 122a to 122d may protrude in a predetermined shape at each position, so that the first flow passage 122f having a recessed shape may be formed between the first and fourth contact points 122a, 122d and the second and third contact points 122b, 122c. The first flow passage 122f may be formed to extend in the circumferential direction at an end of the ground protrusion 122.

[0084] The first flow passage 122f may intersect with the above-mentioned second flow passage 122e to form a "cross"-shaped flow passage. As a result, the first flow passage 122f in the circumferential direction and the second flow passage 122e in the front-rear direction may be formed by the first to fourth contact points 122a to 122d at the end of the ground protrusion 122. Such first and second flow passages 122f, 122e may provide a flow path through which the cooling oil can flow in the front-rear or left-right direction of the shaft 10.

[0085] Meanwhile, the first to fourth contact points 122a to 122d may have a gently curved surface shape at their contact portions with the shaft 10. Also, the first to fourth contact points 122a to 122d may contact the shaft 10 in a type of point contact or a correspondingly small surface contact form. This is to reduce friction with the shaft 10 and induce a smooth flow of the cooling oil.

[0086] Figure 8 is a first cross-sectional view of the ground protrusion shown in Figure 6. Figure 9 is a second cross-sectional view of the ground protrusion shown in Figure 6. Figure 8 illustrates a cross-section along line C3-C3 shown in Figure 6. Figure 9 illustrates a cross-section along line C4-C4 shown in Figure 6.

[0087] 8 and 9, the ground protrusion 122 may include a vertical extension 122g extending from the ring body 121 and a lateral extension 122h extending further in the lateral direction from an end of the vertical extension 122g.

[0088] The vertical extension 122g may be formed to extend radially inward from the ring body 121 toward the central axis S1 by a predetermined amount. The ratio of a first width W1 at an upper end of the vertical extension 122g to a second width W2 at a lower end may be formed to be smaller by a predetermined amount so as to more appropriately accommodate the rotation and surface shape of the shaft 10. In addition, the vertical extension 122g may have a shape in which the width generally decreases from the first width W1 to the second width W2.

[0089] The vertical extension 122g may have one or more guide grooves 122i, 122j formed therein. The guide grooves 122i, 122j may guide the ground protrusion 122 to be elastically deformed appropriately in response to the shaft 10.

[0090] Preferably, the vertical extension 122g may have a first guide groove 122i and a second guide groove 122j formed therein. The first and second guide grooves 122i and 122j may be spaced apart from each other by a predetermined distance along the length of the vertical extension 122g.

[0091] More preferably, the first guide groove 122i is disposed on one side (upper side in the drawing) of the vertical extension portion 122g adjacent to the ring body 121 to induce elastic deformation of the vertical extension portion 122g relative to the ring body 121. Also, the second guide groove 122j is disposed on the other side (lower side in the drawing) of the vertical extension portion 122g adjacent to the horizontal extension portion 122h to induce elastic deformation of the horizontal extension portion 122h relative to the vertical extension portion 122g.

[0092] The first guide groove 122i may be recessed to a predetermined extent on one side of the vertical extension portion 122g adjacent to the ring body 121. Also, the second guide groove 122j may be recessed to a predetermined extent on the other side of the vertical extension portion 122g adjacent to the horizontal extension portion 122h.

[0093] If necessary, the first guide groove 122i may be recessed with a curvature m1 greater than the second guide groove 122j by a predetermined amount. That is, the first guide groove 122i may be recessed with a first curvature m1, and the second guide groove 122j may be recessed with a second curvature m2 smaller than the first curvature m1 by a predetermined amount. Such first and second guide grooves 122i and 122j can induce elastic deformation corresponding to the surface of the shaft 10 while ensuring an appropriate adhesion force to the shaft 10.

[0094] Meanwhile, the lateral extension 122h may be formed to extend rearward from an end of the vertical extension 122g. In an initial state where it is not in contact with the shaft 10, the lateral extension 122h may be formed to extend and incline so as to approach the central axis S1. This allows the second and third contact points 122b and 122c at the rear end of the lateral extension 122h to be in close contact with the shaft 10 with appropriate elasticity.

[0095] 9 illustrates an initial state before the ground protrusion 122 contacts the shaft 10. In the initial state, the first and fourth contact points 122a, 122d and the first flow passage 122f may be arranged to form a generally corresponding plane. The first flow passage 122f between the first and fourth contact points 122a, 122d and the second and third contact points 122b, 122c may be more clearly formed as the lateral extension 122h is elastically deformed by contact with the shaft 10.

[0096] Figure 10 is a diagram showing the installation state of the ground prongs shown in Figure 9. Figure 10 shows an ideal installation state of the ground prongs.

[0097] 10, the ground protrusion 122 in the state shown in Fig. 9 may contact the outer circumferential surface of the shaft 10 and be elastically deformed to a predetermined extent into the shape shown in Fig. 10. Due to the elastic deformation of the ground protrusion 122, the second and third contact points 122b and 122c may elastically contact the outer circumferential surface of the shaft 10, and the first and fourth contact points 122a and 122d may elastically contact the outer circumferential surface of the shaft 10 at positions spaced a predetermined distance forward from the above.

[0098] Due to the above-mentioned contact configuration, a first passage 122f may be formed between the first and fourth contact points 122a, 122d and the second and third contact points 122b, 122c. The first passage 122f may extend in the circumferential direction of the shaft ground ring 120 (see FIG. 7).

[0099] In the assembly 100 of this embodiment as described above, the grounding protrusion 122 comes into contact with the shaft 10, and the leakage current flowing along the shaft 10 can be discharged to the outside. This can prevent electrical corrosion of the bearing.

[0100] In addition, in the assembly 100 of this embodiment, flow paths 122f, 122e in the front-rear or left-right directions (circumferential directions) may be formed with the contact points 122a-122d maintaining contact with each other. The first flow path 122f in the circumferential direction is connected to the outer circumferential surface of the shaft 10 through a gap G1, and the second flow path 122e in the front-rear direction is directly connected to the outer circumferential surface of the shaft 10. Therefore, oil for cooling or the like is quickly discharged to the outside, and deterioration of insulation performance due to oil can be effectively prevented.

[0101] In addition, the assembly 100 of this embodiment uses a method in which a plurality of contact points 122a to 122d contact the shaft 10, so that it can more appropriately deal with misalignment during assembly or imbalance of the shaft 10.

[0102] Furthermore, due to the above-mentioned characteristics, the assembly 100 of this embodiment can maintain a proper grounding condition even in an oil-cooled environment where oil is used as a cooling medium, and can be adapted to be suitable for use in high-capacity electric motors.

[0103] Figure 11 is a front perspective view of a shaft ground ring according to another embodiment of the present invention, and Figure 12 is an enlarged view of the shaft ground ring shown in Figure 11.

[0104] 11 and 12 illustrate another embodiment of the above-mentioned shaft ground ring 120. Specifically, the shaft ground ring 220 of this embodiment may include a ring body 221 and a plurality of ground protrusions 222 formed on the ring body 221. This is similar to the above-mentioned embodiment.

[0105] Here, the ground protrusion 222 according to this embodiment may include a first ground protrusion 223 and a second ground protrusion 224 .

[0106] The first and second ground protrusions 223, 224 may be formed similarly to each other, but may have different directions, i.e., the first ground protrusion 223 may be formed toward the front, and the second ground protrusion 224 may be formed toward the rear.

[0107] Specifically, the first ground protrusion 223 may include a first vertical extension 223a extending from the ring body 221 and a first horizontal extension 223b extending forward from an end of the first vertical extension 223a. The first vertical extension 223a may have first and second guide grooves 223c and 223d formed on a front surface thereof, similar to the ground protrusion 122 of the above-mentioned embodiment. The second ground protrusion 224 may include a second vertical extension 224a extending from the ring body 221 and a second horizontal extension 224b extending rearward from an end of the second vertical extension 224a. The second vertical extension 224a may have first and second guide grooves 224c and 224d formed on a rear surface thereof, similar to the ground protrusion 122 of the above-mentioned embodiment.

[0108] Meanwhile, the first and second ground protrusions 223, 224 may each be provided in a plurality. Also, the plurality of first and second ground protrusions 223, 224 may be arranged in a circumferential direction with one or more of them alternately repeated. In this embodiment, the first and second ground protrusions 223, 224 are alternately arranged one by one. As another example, the first and second ground protrusions 223, 224 may each be alternately arranged in twos, or different numbers of the first and second ground protrusions 223, 224 may be alternately arranged, such as two first ground protrusions 223 and three second ground protrusions 224.

[0109] The shaft ground ring 220 of the above embodiment has an advantage that the assembly direction is not specified, that is, since the first and second ground protrusions 223 and 224 extending forward or backward are provided on one ring body 221, the shaft ground ring 220 can be assembled without being limited to a specific assembly direction.

[0110] FIG. 13 is a partial cross-sectional perspective view of a shaft ground ring according to a third embodiment of the present invention.

[0111] 13, the shaft ground ring 320 of this embodiment may include a ring body 321 and a plurality of ground protrusions 322 formed on the ring body 321. This is similar to the above-described embodiment.

[0112] The shaft ground ring 320 of this embodiment may have differences in the shape of the ground protrusions 322.

[0113] Specifically, in this embodiment, the ground protrusion 322 may be formed to protrude toward the central axis S1 from the ring body 321. A plurality of ground protrusions 322 may be provided, and the plurality of ground protrusions 322 may be spaced apart from each other at a predetermined interval G1 along the inner circumference of the ring body 321.

[0114] Here, unlike the above-mentioned embodiment, the ground protrusion 322 of this embodiment does not have a direction in the front-rear direction. That is, the ground protrusion 322 may be formed to be substantially flush with the ring body 321 and extend toward the central axis S1. In other words, the ground protrusion 322 may be formed to extend in a direction substantially perpendicular to the central axis S1.

[0115] As described above, the shaft ground ring 320 of this embodiment can be assembled to the shaft 10 without specifying the front-to-back assembly direction. This is similar to the second embodiment described above.

[0116] In addition, the ground protrusion 322 of this embodiment may have guide grooves 322i, 322i' formed at a base end portion extending from the ring body 321. In this embodiment, the guide grooves 322i, 322i' may be formed at radially outer portions of the ground protrusion 322 generally adjacent to the ring body 321.

[0117] The guide grooves 322i, 322i' may be recessed to a predetermined extent inward in the thickness direction of the ground protrusion 322. Also, in this embodiment, the guide grooves 322i, 322i' may be formed on both the front and rear surfaces of the ground protrusion 322. As a result, the ground protrusion 322 may have a relatively thin thickness at the base end portion connected to the ring body 321 compared to other portions.

[0118] The guide grooves 322 i and 322 i ′ guide the elastic deformation of the ground protrusion 322 so that the ground protrusion 322 can be properly attached to the shaft 10 .

[0119] Here, in this embodiment, a pair of guide grooves 322i, 322i' are formed on the front and rear surfaces, and can appropriately correspond to the front and rear assembly direction of the shaft ground ring 320. That is, when the shaft ground ring 320 is inserted into the shaft 10 in the forward direction in the illustrated state, the rear guide groove 322i' induces elastic deformation of the ground protrusions 322, and proper assembly can be performed. Conversely, when the shaft ground ring 320 is inserted into the shaft 10 in the backward direction, the front guide groove 322i induces elastic deformation of the ground protrusions 322, and proper assembly can be performed.

[0120] Meanwhile, the ground protrusion 322 of this embodiment may have a first contact point 322a and a fourth contact point 322d formed at the end facing the shaft 10.

[0121] In the ground protrusion 322 of this embodiment, the second contact point 122b and the third contact point 122c are omitted when compared with the above-described embodiment. The first contact point 322a and the fourth contact point 322d may be spaced apart from each other by a predetermined distance in the circumferential direction, and a second flow passage 322e may be provided therebetween. The second flow passage 322e may provide a flow passage in the front-rear direction. In this embodiment, the first flow passage 122f in the circumferential direction may be omitted.

[0122] Fig. 14 is a front view of a shaft ground ring assembly according to a fourth embodiment of the present invention. Fig. 15 is a cross-sectional view of the shaft ground ring shown in Fig. 14. Fig. 15 is a cross-sectional view taken along line C4-C4 shown in Fig. 14.

[0123] 14 and 15, the shaft ground ring assembly 400 of this embodiment may include a housing 410 and a shaft ground ring 420.

[0124] Here, this embodiment is different from the above-described embodiments in that the ground protrusions 422 of the shaft ground ring 420 are formed on the outer periphery of the shaft ground ring 420 .

[0125] Specifically, the housing 410 of this embodiment may include a housing body 411 and a housing cover 412 , and the shaft ground ring 420 may be supported between the housing body 411 and the housing cover 412 .

[0126] Here, the housing 410 may be installed on a shaft. That is, in this embodiment, the housing 410 may be fastened to the shaft and directly grounded. The shaft may be press-fitted into the housing 410. Also, the shaft ground ring 420 may be fastened to the housing 410 so that the housing 410 and the shaft ground ring 420 may rotate together with the shaft.

[0127] Also, the shaft ground ring 420 may have a ground protrusion 422 formed on the radially outer side. A plurality of ground protrusions 422 may be formed, and the plurality of ground protrusions 422 may be spaced apart along the outer periphery of the shaft ground ring 420 with a predetermined gap therebetween. Each ground protrusion 422 may be formed in a manner similar to the above-described embodiments, but may be arranged in the opposite direction toward the radially outer side. This embodiment may function in the same or similar manner as the above-described embodiments, except that the relative rotation subjects are reversed.

[0128] Although the embodiments of the present invention have been described above, a person having ordinary knowledge in the relevant technical field may modify or change the present invention in various ways by adding, changing, deleting or adding components within the scope of the technical idea of ​​the present invention described in the claims, and this may also be considered to be within the scope of the claims of the present invention.

Claims

1. The device is fastened to the shaft (10) of an electric motor to prevent electrolytic corrosion caused by leakage current, A ring body (121) extending around the outer circumferential surface of the shaft (10); and a plurality of ground protrusions (122) protruding from an inner circumferential surface of the ring body (121) to contact an outer circumferential surface of the shaft (10), the ground protrusions (122) being spaced apart from each other with a predetermined gap (G1) along the ring body (121); Each of the plurality of ground prongs (122) comprises: A plurality of contact points (122a-122d) that contact the outer circumferential surface of the shaft (10); and a shaft ground ring including one or more channels (122e, 122f) in a recessed form extending in a front-to-rear direction or in a circumferential direction of the ring body (121) between the plurality of contact points (122a-122d).

2. The gap (G1) is The shaft ground ring of claim 1 , further comprising a groove formed in the shaft (10) and a groove formed in the shaft (10).

3. The plurality of contact points (122a to 122d) are a first contact point (122a) contacting one side of the outer circumferential surface of the shaft (10); a second contact point (122b) spaced apart from the first contact point (122a) in the front-rear direction; a third contact point (122c) circumferentially spaced from the second contact point (122b); and 2. The shaft ground ring of claim 1, further comprising: a fourth contact point (122d) spaced apart in the fore-aft direction from the third contact point (122c) so as to correspond to the first contact point (122a).

4. The flow paths (122e, 122f) are a first flow passage (122f) extending circumferentially between the first and fourth contact points (122a, 122d) and the second and third contact points (122b, 122c); and 4. The shaft ground ring of claim 3, further comprising: a second flow passage (122e) extending in a front-to-rear direction between the first and second contact points (122a, 122b) and the third and fourth contact points (122c, 122d).

5. The ground protrusion (122) is a longitudinal extension (122g) extending from the ring body (121) toward the central axis (S1) of the shaft (10); and 2. The shaft ground ring of claim 1, further comprising: a lateral extension portion (122h) that extends forward or rearward from an end of the longitudinal extension portion (122g) but is formed to extend and tilt toward a central axis (S1) of the shaft (10) in an initial state in which the lateral extension portion (122h) is not in contact with the shaft (10).

6. The lateral extension (122h) a first contact point (122a) contacting one side of the outer circumferential surface of the shaft (10); a second contact point (122b) spaced apart from the first contact point (122a) in the front-rear direction; and 6. The shaft ground ring of claim 5, further comprising: a first flow passage (122f) formed in a circumferential direction between the first contact point (122a) and the second contact point (122b) by elastically deforming the lateral extension (122h) upon installation on the shaft (10).

7. A device for preventing electrolytic corrosion caused by leakage current by being fastened to a shaft (10) of an electric motor, A ring body (121) extending around the outer circumferential surface of the shaft (10); and a ground protrusion (122) formed on an inner peripheral surface of the ring body (121) to contact an outer peripheral surface of the shaft (10), the ground protrusion (122) being spaced apart from each other with a predetermined gap (G1) along the ring body (121); The ground protrusion (122) is a longitudinal extension (122g) extending from the ring body (121) toward the central axis (S1) of the shaft (10); a lateral extension portion (122h) extending forward or backward from an end of the longitudinal extension portion (122g) but extending in an inclined manner so as to approach the central axis (S1) of the shaft (10) in an initial state in which the lateral extension portion (122h) does not contact the shaft (10); a first guide groove (122i) having a first curvature (m1) between the ring body (121) and the longitudinal extension (122g) and recessed to guide elastic deformation of the longitudinal extension (122g); and a second guide groove (122j) recessed between the vertical extension portion (122g) and the horizontal extension portion (122h) with a second curvature (m2) smaller than the first curvature (m1) to guide elastic deformation of the horizontal extension portion (122h).

8. The ring body (121) and the ground protrusion (122) are 10. The shaft ground ring of claim 1, which is integrally formed and is formed in whole or in part from a conductive plastic material.

9. A device for preventing electrolytic corrosion caused by leakage current by being fastened to a shaft (10) of an electric motor, A ring body (121) extending around the outer circumferential surface of the shaft (10); and a ground protrusion (122) formed on an inner peripheral surface of the ring body (121) to contact an outer peripheral surface of the shaft (10), the ground protrusion (122) being spaced apart from each other with a predetermined gap (G1) along the ring body (121); The ground protrusion is a plurality of first ground prongs (223); and a plurality of second ground protrusions (224) arranged alternately with the plurality of first ground protrusions (223); The first ground protrusion (223) is a first longitudinal extension (223a) extending from said ring body; and a first horizontal extension (223b) extending forward from an end of the first vertical extension (223a); The second ground protrusion (224) is a second longitudinal extension (224a) extending from said ring body; and a second lateral extension (224b) extending rearwardly from an end of said second longitudinal extension (224a).

10. A device for preventing electrolytic corrosion caused by leakage current, which is fastened to a shaft (10) of an electric motor, A ring body (121) extending around the outer circumferential surface of the shaft (10); and a ground protrusion (122) formed on an inner peripheral surface of the ring body (121) to contact an outer peripheral surface of the shaft (10), the ground protrusion (122) being spaced apart from each other with a predetermined gap (G1) along the ring body (121); The ground protrusion is a first contact point (322a) and a fourth contact point (322d) spaced apart in the circumferential direction of the shaft and each contacting the outer circumferential surface of the shaft to define a second forward / backward flow passage (322e) therebetween; and A shaft ground ring including: a guide groove (322i, 322i') formed so that the front and rear surfaces are recessed at the connection portion with the ring body, and which induces elastic deformation forward or backward when inserted and fastened to the shaft.

11. A shaft ground ring (120) according to claim 1; and a housing (110) fastened to receive the shaft ground ring (120) therein.

12. The housing (110) comprises: A housing body (111) having a predetermined cross section and extending in a circumferential direction; and a housing cover (112) fastened to the housing body (111) to restrict the shaft ground ring (120) from coming off; The housing body (111) is A ring support surface (111a) that contacts and supports the outer circumferential surface of the shaft ground ring (120); and 12. The shaft ground ring assembly of claim 11, further comprising: a swaging (111b) formed rearward of the ring support surface (111a) and extending at an incline so as to approach the central axis (S1) of the shaft (10) as it goes rearward, to limit rearward removal of the housing cover (112).

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