Shaft grounding ring based on capacitance principle and motor

Abstract

The utility model discloses a shaft grounding ring based on a capacitance principle and a motor. The shaft grounding ring comprises an outer skeleton, at least one inner skeleton and at least one conductor. An assembly hole is formed in the center of the outer framework, and a motor rotating shaft penetrates through the assembly hole; the outer framework is also provided with a groove around the assembly hole; in the groove, the conductors and the inner frameworks are alternately arranged in sequence, and the inner frameworks are used for being matched with the outer framework to fix the conductors; the electric conductor at least partially extends into the assembly hole along the radial direction of the assembly hole; when the shaft grounding ring sleeves the motor rotating shaft, an insulating medium is arranged between contact areas of the electric conductor and the motor rotating shaft, and the insulating medium is used for forming insulation between the electric conductor and the motor rotating shaft. According to the shaft grounding ring based on the capacitance principle and the motor provided by the utility model, the voltage level on the bearing is reduced, and the risk of electric corrosion damage to the bearing is reduced.

Description

Technical Field

[0001] This utility model relates to the field of motor technology, and in particular to a shaft grounding ring and motor based on the principle of capacitance. Background Technology

[0002] When a motor is working, a shaft voltage is usually generated between the motor shaft and the motor housing. If the shaft voltage exceeds a certain value, it is easy to break down, generating a large instantaneous shaft current, which leads to electro-corrosion of the motor bearing. This electro-corrosion further aggravates the damage to the motor bearing during motor operation.

[0003] In existing technologies, a low-resistance shaft grounding ring is typically added near the motor shaft to conduct shaft charge to the housing for grounding. However, in high-voltage oil-cooled motors, the charge conduction is unstable due to the influence of the oil, and the motor shaft still suffers from electro-corrosion. Utility Model Content

[0004] This invention provides a shaft grounding ring and motor based on the principle of capacitance, which reduces the voltage level on the bearing and reduces the risk of electrical corrosion damage to the bearing.

[0005] In a first aspect, this utility model provides a shaft grounding ring, comprising: an outer frame, at least one inner frame, and at least one conductor;

[0006] The outer frame has a mounting hole at its center for the motor shaft to pass through; the outer frame also has a groove around the mounting hole; the conductor and the inner frame are alternately arranged in the groove, and the inner frame is used to cooperate with the outer frame to fix the conductor; the conductor extends at least partially into the mounting hole along the radial direction of the mounting hole.

[0007] When the grounding ring is fitted onto the motor shaft, an insulating medium is provided between the contact area between the conductor and the motor shaft. The insulating medium is used to form insulation between the conductor and the motor shaft.

[0008] Optionally, the conductor includes a fixing portion and an interference portion; the fixing portion and the interference portion are integrally connected; the fixing portion is disposed between adjacent inner frames and / or between the inner frames and the bottom of the groove; the interference portion extends at least partially into the mounting hole along the radial direction of the mounting hole.

[0009] Optionally, the side of the interference fit away from the fixing part forms a through hole; the through hole is coaxial with the mounting hole, and the through hole is used to pass through the motor shaft.

[0010] Optionally, the interference fit includes conductive teeth with gaps between adjacent conductive teeth.

[0011] Optionally, the diameter of the through hole is smaller than the diameter of the motor shaft.

[0012] Optionally, the interference fit between the interference fit and the motor shaft has an interference amount ranging from 2 to 6 mm.

[0013] Optionally, the outer frame includes a first peripheral wall radially along the mounting hole and a second peripheral wall perpendicular to the first peripheral wall; the first peripheral wall and the second peripheral wall form the groove; the inner frame includes a third peripheral wall radially along the mounting hole, and the first peripheral wall and the third peripheral wall press together to clamp the conductor.

[0014] Optionally, the inner frame further includes a fourth peripheral wall perpendicular to the third peripheral wall; the diameter of the fourth peripheral wall enclosing the assembly hole is greater than the diameter of the second peripheral wall enclosing the assembly hole.

[0015] Optionally, the conductor is polytetrafluoroethylene or conductive rubber.

[0016] Secondly, this utility model embodiment also provides a motor, including a motor shaft, a motor housing, and a shaft grounding ring as described in any embodiment of this utility model; the motor shaft is located inside the motor housing, and the shaft grounding ring is sleeved on the motor shaft.

[0017] The technical solution provided by this utility model embodiment involves alternately arranging conductors and inner frames within the groove of the outer frame. When the shaft grounding ring is fitted onto the motor shaft, an insulating medium is provided between the contact area between the conductor and the motor shaft, thereby coupling to form a shaft-oil-conductor capacitor. After the grounding shaft ring is assembled with the electrode shaft, the shaft grounding ring and the bearing are connected in parallel. This utilizes the coupled capacitor to reduce the voltage distribution in the branch, thereby reducing the voltage level on the bearing and lowering the risk of electrical corrosion damage to the bearing. Attached Figure Description

[0018] Figure 1 This invention provides a schematic diagram of the structure of a shaft grounding ring according to an embodiment of the present invention;

[0019] Figure 2 This invention provides a cross-sectional view of a shaft grounding ring according to an embodiment of the present invention.

[0020] Figure 3 This invention provides a schematic diagram of the circuit coupling model of a shaft grounding ring according to an embodiment of the present invention.

[0021] Figure 4 A schematic diagram of another type of shaft grounding ring is provided for embodiments of this utility model;

[0022] Figure 5This provides a cross-sectional structural schematic diagram of another type of shaft grounding ring for embodiments of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0024] With the development of new energy electric drive systems, high-voltage oil-cooled motors have gradually become the mainstream design solution. This not only reduces the size of the motor, but also provides a cooling effect that is far superior to the traditional water-cooling method. However, in an oil-cooled environment, since the motor shaft is in contact with the cooling oil, a layer of "oil film" inevitably adheres to its surface. The thickness of this film depends on the amount of oil in different areas. Due to the insulating properties of the cooling oil, a stable low-resistance connection cannot be established between the shaft grounding ring and the motor shaft, which can lead to electro-corrosion of the motor shaft in some cases.

[0025] In view of this, Figure 1 This is a schematic diagram of the structure of a shaft grounding ring provided in an embodiment of the present invention. Figure 2 A cross-sectional view of a shaft grounding ring is provided in an embodiment of this utility model. See [reference needed]. Figure 1 and Figure 2 It includes: an outer skeleton 110, an inner skeleton 120 and a conductor 130;

[0026] The outer frame 110 has a mounting hole 140 at its center for the motor shaft to pass through; the outer frame 110 also has a groove 150 around the mounting hole 140; within the groove 150, the conductor 130 and the inner frame 120 are alternately arranged, and the inner frame 120 is used to cooperate with the outer frame 110 to fix the conductor 130; the conductor 130 extends at least partially into the mounting hole 140 along the radial direction of the mounting hole 140.

[0027] When the shaft grounding ring is fitted on the motor shaft, an insulating medium is provided between the contact area of ​​the conductor 130 and the motor shaft. The insulating medium is used to form insulation between the conductor 130 and the motor shaft.

[0028] Specifically, the outer frame 110 is the main frame of the shaft grounding ring. A mounting hole 140 is provided at the center of the outer frame 110. The outer frame 110 is circular in shape, allowing the shaft grounding ring to be fitted onto the motor shaft through the mounting hole 140. A groove 150 is also provided inside the outer frame 110 along the circumference of the mounting hole 140. A conductor 130 is placed within the groove 150, and an inner frame 120 is provided on the side adjacent to the conductor 130. The conductor 130 is clamped and fixed by the bottom of the groove 150 of the outer frame 110 and the inner frame 120. The outer frame 110 and the inner frame 120 can be fixedly connected by methods such as fit-fit, riveting, hemming, or hook bending. The conductor 130 has a partial extension area extending into the mounting hole 140. When assembling the electrode shaft, the motor shaft passes through the mounting hole 140, and the conductor 130 contacts the motor shaft, causing the conductor 130 to bend axially. An insulating medium is provided between the contact area between the conductor 130 and the motor shaft. For example, the insulating medium can be cooling oil or lubricating fluid, forming an insulating oil film layer between the contact area of ​​the conductor 130 and the motor shaft. After the grounding ring is assembled with the electrode shaft, the grounding ring and the bearing are connected in parallel. The oil film between the conductor 130 and the electrode shaft acts as the insulating medium, thereby coupling to form a capacitor device of shaft-oil-conductor 130. This capacitor device reduces voltage distribution in the branch circuit, thereby lowering the voltage level on the bearing and reducing the risk of electrical corrosion damage to the bearing.

[0029] For example, Figure 3 A schematic diagram of the circuit coupling model of an axis grounding ring is provided for an embodiment of this utility model. See [link / reference]. Figure 3 It can be seen that a first coupling capacitor C is formed between the stator 210 and the winding 220. WS A second coupling capacitor C is formed between the winding 220 and the motor shaft 230. WR A third coupling capacitor C is formed between the stator 210 and the motor shaft 230. RS A fourth coupling capacitor C is formed between the first bearing 240 and the stator 210. B,BS A fifth coupling capacitor C is formed between the second bearing 250 and the stator 210. B,AS A sixth coupling capacitor C is formed between the motor shaft 230 and the stator 210. RS A seventh coupling capacitor C is formed between the grounding shaft ring and the stator 210. SGR Because the coupling forms a capacitor component of shaft-oil-conductor 130, the coupling capacitance of this branch in the model is increased; that is, a seventh coupling capacitance C is added. SGR The capacitance value. Furthermore, the grounding collar and bearing are connected in parallel, so according to the model, the fourth coupling capacitance C... B,BS Fifth coupling capacitor C B,AS The voltage u of the seventh coupling capacitorB It can be represented as:

[0030]

[0031] u cm This refers to the total shaft voltage. Therefore, by adding a grounding shaft ring, the grounding shaft ring can form a coupling capacitance with the motor shaft 230, thereby reducing the voltage level on the bearing and thus reducing the risk of electrical corrosion damage to the bearing.

[0032] Figure 4 This invention provides a schematic diagram of another type of shaft grounding ring. Figure 5 A cross-sectional view of another type of shaft grounding ring is provided for embodiments of this utility model. See also... Figure 4 and Figure 5 It includes: an outer skeleton 110, at least one inner skeleton 120, and at least one conductor 130; within the groove 150, the conductor 130 and the inner skeleton 120 are alternately arranged, thereby forming a multilayer of conductor 130, for example. Figure 4 To form a two-layer conductor 130, Figure 5 The conductor 130 forms a three-layer structure. Therefore, after assembling the electrode shaft, the multiple layers of conductor 130 couple to form a shaft-oil-conductor 130 capacitor structure. In other words, the multiple layers of conductor 130 form parallel coupling capacitors, further increasing the capacitance value of this branch in the model. Therefore, the voltage Ub can be further reduced, thereby further lowering the voltage level on the bearing and reducing the risk of electrical corrosion damage to the bearing.

[0033] See also Figure 2 , Figure 4 and Figure 5 Optionally, the conductor 130 includes a fixing portion 131 and an interference portion 132; the fixing portion 131 and the interference portion 132 are integrally connected; the fixing portion 131 is disposed between adjacent inner frames 120 and / or between the inner frame 120 and the bottom of the groove 150; the interference portion 132 extends at least partially into the mounting hole 140 along the radial direction of the mounting hole 140.

[0034] Specifically, the conductor 130 includes an integrally formed fixing part 131 and an interference fit part 132. In the structure of a single-layer conductor 130, the fixing part 131 is disposed between the inner skeleton 120 and the bottom of the groove 150, and is clamped and fixed by the inner skeleton 120 and the bottom of the groove 150. In the structure of a multi-layer conductor 130, the fixing part 131 is disposed between the inner skeleton 120 and the bottom of the groove 150, and between adjacent inner skeletons 120, to achieve fixation of the multi-layer conductor 130. The inner skeleton 120 is annular to facilitate the assembly of the motor shaft 230. The interference fit part 132 extends into the assembly hole 140. Therefore, the motor shaft 230 bends during assembly due to contact with the interference fit part 132. By adjusting the extension dimension of the interference fit part 132, the contact area between the interference fit part 132 and the surface of the motor shaft 230 can be adjusted, thereby adjusting the capacitance value of the coupling capacitor formed by the shaft-oil-conductor 130.

[0035] Optionally, the interference fit 132 forms a through hole on the side away from the fixing part 131; the through hole is coaxial with the mounting hole 140 and is used to pass through the motor shaft 230. That is, the conductor 130 is generally annular, and a through hole is provided at the center of the conductor 130, wherein the through hole can be formed by the interference fit 132. The diameter of the through hole can be smaller than the diameter of the mounting hole 140, so that in the assembled state, the interference fit 132 can make contact with the motor shaft 230, causing the interference fit 132 to bend. For example, the interference fit 132 can be a continuous and complete annulus. In some embodiments, the interference fit 132 can also be a discontinuous annulus, for example, the interference fit 132 includes conductive teeth with gaps between adjacent conductive teeth. The gaps between the conductive teeth can prevent excessive stress from acting on the motor shaft 230, reducing wear of the conductive teeth in the contact area with the motor shaft 230. In this embodiment of the utility model, the shaft grounding ring allows the conductive teeth to directly contact the motor shaft 230 in traditional applications, enabling the direct discharge of the shaft current generated by the motor shaft 230. However, in cases with a high oil content, the coupling capacitance formed by the shaft, oil, and conductor 130 can be utilized to reduce the voltage level on the bearing, thus improving the application flexibility of the shaft grounding ring. It should be noted that the shape and size of the conductive teeth are not limited here; for example, the shape of the conductive teeth can be T-shaped, square, or trapezoidal, etc.

[0036] In some embodiments, the capacitance value of the coupling capacitor can be adjusted by adjusting the design of the conductor 130, for example, by different interference fits or the number of conductors 130. When there is an interference fit between the interference fit 132 and the motor shaft 230, that is, when the diameter of the through hole formed by the interference fit 132 is smaller than the diameter of the mounting hole 140, contact can occur between the interference fit 132 and the motor shaft 230. The interference fit 132 may bend, and there may be different contact areas between the interference fit 132 and the motor shaft 230, thereby adjusting the capacitance value of the coupling capacitor. By matching with the coupling capacitor in the model, the bearing pressure is derived. For example, the interference fit between the interference fit 132 and the motor shaft 230 ranges from 2 to 6 mm.

[0037] See also Figure 2 Optionally, the outer frame 110 includes a first peripheral wall 111 radially along the mounting hole 140 and a second peripheral wall 112 perpendicular to the first peripheral wall 111; the first peripheral wall 111 and the second peripheral wall 112 form a groove 150; the inner frame 120 includes a third peripheral wall 121 radially along the mounting hole 140. The first peripheral wall 111 and the third peripheral wall 121 press and clamp the conductor 130.

[0038] Specifically, the first peripheral wall 111 and the second peripheral wall 112 form a groove 150. One end of the first peripheral wall 111 encloses and forms a mounting hole 140, and one end of the third peripheral wall 121 of the inner frame 120 encloses and forms a mounting hole 140. The conductor 130 is pressed and fixed by the first peripheral wall 111 and the third peripheral wall 121, wherein the pressed portion of the conductor 130 is the fixing portion 131, and the portion within the mounting hole 140 is the interference portion 132 of the conductor 130. The circular diameter enclosed by the end of the third peripheral wall 121 near the second peripheral wall 112 is larger than the circular diameter enclosed by the second peripheral wall 112 along the direction of the mounting hole 140. Therefore, an interference fit can be provided between the inner frame 120 and the outer frame 110, and the inner frame 120 and the outer frame 110 can be fixed in the groove 150 by interference fit.

[0039] See Figure 2In some embodiments, the inner frame 120 further includes a fourth wall 122 perpendicular to the third peripheral wall 121; the diameter of the fourth peripheral wall 122 enclosing the assembly hole 140 is larger than the diameter of the second peripheral wall 112 enclosing the assembly hole 140. Specifically, the axial width of the third peripheral wall 121 can be smaller than the axial width of the second peripheral wall 112, thereby preventing the inner frame 120 from protruding after the inner frame 120 and the outer frame 110 are assembled. The larger diameter of the fourth peripheral wall 122 enclosing the assembly hole 140 also provides an interference fit between the inner frame 120 and the outer frame 110, allowing the inner frame 120 and the outer frame 110 to be fixed in the groove 150 by interference fit. Furthermore, the fourth peripheral wall 122 can provide support for the inner frame 120, improving the pressing stability of the inner frame 120.

[0040] Optionally, the conductor 130 is made of an elastic conductive material, such as polytetrafluoroethylene (PTFE) or conductive rubber. Therefore, the interference fit 132 can not only bend elastically, but also has its own restoring force to return to its initial shape, which can, to a certain extent, ensure the stable shape between the conductor 130 and the motor shaft 230 during the service life.

[0041] This utility model embodiment also provides a motor, including a motor shaft 230, a motor housing, and a shaft grounding ring according to any embodiment of this utility model. The motor shaft 230 is located inside the motor housing, and a motor bearing is sleeved on the motor shaft 230 to support the motor shaft 230 and ensure stable installation of the motor shaft 230 within the motor housing. The shaft grounding ring is sleeved on the motor shaft 230, and can be considered as the shaft grounding ring and the motor bearing being connected in parallel. An insulating medium is provided between the contact area between the conductor 130 and the motor shaft 230. For example, the insulating medium can be cooling oil, and an insulating oil film layer will be formed between the contact area between the conductor 130 and the motor shaft 230. In the circuit model, the cooling oil between the conductor 130 and the electrode shaft serves as the insulating medium, thereby coupling to form a capacitor device of shaft-oil-conductor 130. The capacitor device reduces the voltage distribution of the branches, thereby reducing the voltage level on the bearing and reducing the risk of electrical corrosion damage to the bearing. This solves the problem of high resistance and poor voltage reduction effect of the shaft grounding ring when there is a lot of oil and the oil film is thick.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. A shaft grounding ring, characterized in that, include: An exoskeleton, at least one inner skeleton, and at least one conductor; The outer frame has a mounting hole at its center for the motor shaft to pass through; the outer frame also has a groove around the mounting hole; the conductor and the inner frame are alternately arranged in the groove, and the inner frame is used to cooperate with the outer frame to fix the conductor; the conductor extends at least partially into the mounting hole along the radial direction of the mounting hole. When the grounding ring is fitted onto the motor shaft, an insulating medium is provided between the contact area between the conductor and the motor shaft. The insulating medium is used to form insulation between the conductor and the motor shaft.

2. The shaft grounding ring according to claim 1, characterized in that, The conductor includes a fixing part and an interference part; the fixing part and the interference part are integrally connected; the fixing part is disposed between adjacent inner frames and or between the inner frames and the bottom of the groove; the interference part extends at least partially into the assembly hole along the radial direction of the assembly hole.

3. The shaft grounding ring according to claim 2, characterized in that, The interference fit portion forms a through hole on the side away from the fixing portion; the through hole is coaxial with the mounting hole and is used to pass through the motor shaft.

4. The shaft grounding ring according to claim 3, characterized in that, The interference fit includes conductive teeth, with gaps between adjacent conductive teeth.

5. The shaft grounding ring according to claim 4, characterized in that, The diameter of the through hole is smaller than the diameter of the motor shaft.

6. The shaft grounding ring according to claim 5, characterized in that, The interference fit between the interference fit and the motor shaft is 2-6 mm.

7. The shaft grounding ring according to claim 1, characterized in that, The outer frame includes a first peripheral wall radially along the assembly hole and a second peripheral wall perpendicular to the first peripheral wall; the first peripheral wall and the second peripheral wall form the groove; the inner frame includes a third peripheral wall radially along the assembly hole, and the first peripheral wall and the third peripheral wall are pressed together to clamp the conductor.

8. The shaft grounding ring according to claim 7, characterized in that, The inner frame also includes a fourth circumferential wall perpendicular to the third circumferential wall; the diameter of the fourth circumferential wall enclosing the assembly hole is greater than the diameter of the second circumferential wall enclosing the assembly hole.

9. The shaft grounding ring according to any one of claims 1-8, characterized in that, The conductor is polytetrafluoroethylene or conductive rubber.

10. An electric motor, characterized in that, It includes a motor shaft, a motor housing, and a shaft grounding ring as described in any one of claims 1-9; the motor shaft is located inside the motor housing, and the shaft grounding ring is sleeved on the motor shaft.

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