sealing device

Abstract

To provide a sealing device capable of actualizing long-time continuity between a rotary shaft and a housing in a low-cost and space-saving manner.SOLUTION: A sealing device 40 is arranged in a space 107 between an outer face 20a of a rotary shaft 20 and an inner face 38s of a housing 38 having a shaft hole into which the rotary shaft is inserted, as part of the shaft hole, for sealing the space. When the rotary shaft is rotated, the sealing device is pushed against the inner face as part of the shaft hole of the housing to actualize continuity between the rotary shaft and the housing.SELECTED DRAWING: Figure 3

Description

【Technical Field】 【0001】 The present invention relates to a sealing device. 【Background Art】 【0002】 Generally, in an EV (Electric Vehicle) or HEV (Hybrid Electric Vehicle), a sealing device, which is an oil seal, is provided between the rotating shaft of a motor and a housing to prevent leakage of lubricant sealed inside the machine to the outside. In such EVs and HEVs, electromagnetic noise is generated by the induced current generated in the motor, and there is concern about the adverse effect on electronic devices. 【0003】 As a related conventional method, for example, Patent Document 1 describes an oil seal in which a rubber-like elastic material oil lip and a dust lip are adhered to a reinforcing ring having a substantially L-shaped cross section. The dust lip is made of a woven or non-woven fabric mixed with a conductive material, and at least a part of the fitting surface of the reinforcing ring is exposed. Such an oil seal is described as avoiding the problem of noise generation seen when using a normal oil seal because the conductivity between the housing and the shaft is ensured via the dust lip and the reinforcing ring. 【0004】 Furthermore, Patent Document 2 describes a sealing device disposed between a rotating shaft connected to a motor and a housing to seal the inside and outside of the machine, comprising: a conductive elastic body portion having a lip that slidably contacts the rotating shaft and is disposed between the rotating shaft and the housing to seal lubricant into the machine while suppressing the intrusion of foreign matter from the outside; a conductive reinforcing ring integrally formed with the elastic body portion and having a conductive surface that contacts the inner circumferential surface of the housing; and a conductive metal ring having a first conductive surface that contacts the elastic body portion on the rotating shaft side and a second conductive surface that contacts the reinforcing ring on the housing side, wherein the conductivity between the first conductive surface and the second conductive surface is higher than that of the elastic body portion. It is stated that with such a sealing device, electrical conductivity between the rotating shaft connected to the motor and the housing can be achieved smoothly, at low cost and in a space-saving manner. 【0005】 Patent Document 3 discloses a technique for electrically connecting the rotating shaft of a motor to a metal motor housing, thereby dissipating electromagnetic noise induced in the rotating shaft into the motor housing. In particular, Figure 4 of Patent Document 3 discloses the manufacture of a sealing device, which is an oil seal placed between the rotating shaft of the motor and the housing, from conductive rubber. [Prior art documents] [Patent Documents] 【0006】 [Patent Document 1] Japanese Utility Model Publication No. 60-167263 [Patent Document 2] Japanese Patent Publication No. 2020-60240 [Patent Document 3] Japanese Patent Publication No. 2000-244180 [Overview of the project] [Problems that the invention aims to solve] 【0007】 When a conductive sealing device is placed around the rotating shaft of a motor to allow electromagnetic noise to escape from the rotating shaft to the housing, it is desirable to ensure contact between the conductive sealing device and the rotating shaft (made of metal, etc.), and between the sealing device and the housing (made of metal, etc.). The same applies when a conductive sealing device is placed around the rotating shaft of a generator. Furthermore, the same applies when a conductive sealing device is placed around the rotating shaft that is rotated by the rotating shaft of a motor, and the rotating shaft that rotates the rotating shaft of a generator. 【0008】 The present invention provides a sealing device that can achieve electrical conductivity between a rotating shaft and a housing for a long period of time, at low cost, and in a space-saving manner. [Means for solving the problem] 【0009】 The inventors diligently studied and conducted research to solve the above problems, and have completed the present invention. The present invention is as follows (1) to (3). (1) A sealing device that is placed in the gap between the outer surface of a rotating shaft and the inner surface constituting the shaft hole in a housing having a shaft hole into which the rotating shaft is inserted, and that seals this gap, A sealing device that allows electrical communication between the rotating shaft and the housing, which is pressed against the inner surface constituting the shaft hole in the housing when the rotating shaft rotates. (2) An annular sheath tube portion fixed to the outer surface of the rotating shaft, A conductive portion which is ring-shaped, with the outer circumference of the ring in contact with the inner surface of the housing and the main surface fixed to the sheath tube portion, A sealing device as described in (1) above, having the following: (3) The sealing device according to (2) above, wherein the force pressing the conductive portion against the inner surface of the housing increases due to the centrifugal force generated by the rotation of the rotating shaft. [Effects of the Invention] 【0010】 According to the present invention, a sealing device can be provided that can achieve electrical conductivity between the rotating shaft and the housing for a long period of time, at low cost, and in a space-saving manner. [Brief explanation of the drawing] 【0011】 [Figure 1] This figure shows a power transmission system for an electric vehicle equipped with a conductive device according to an embodiment of the present invention. [Figure 2] This figure shows a power transmission system for another electric vehicle equipped with a conductive device according to an embodiment of the present invention. [Figure 3] This is a schematic cross-sectional view showing a preferred embodiment of the sealing device of the present invention. [Figure 4] This is a schematic cross-sectional view showing another preferred embodiment of the sealing device of the present invention. [Figure 5] A schematic cross-sectional view showing yet another preferred embodiment of the sealing device of the present invention. [Figure 6] A schematic cross-sectional view showing yet another preferred embodiment of the sealing device of the present invention. [Modes for carrying out the invention] 【0012】 The present invention will now be described. The present invention relates to a sealing device that is placed in the gap between the outer surface of a rotating shaft and the inner surface constituting the shaft hole in a housing having a shaft hole into which the rotating shaft is inserted, and seals this gap, wherein when the rotating shaft rotates, the sealing device is pressed against the inner surface constituting the shaft hole in the housing, and is capable of electrical communication between the rotating shaft and the housing. Such a sealing device will also be referred to as "the sealing device of the present invention" below. 【0013】 The sealing device of the present invention is preferably attached to the outer surface of the rotating shaft. In this case, as the rotating shaft rotates, centrifugal force is applied to the sealing device of the present invention, causing the sealing device to be pressed against the inner surface of the housing. As a result, the sealing device of the present invention stably adheres to the inner surface of the housing, thereby ensuring electrical contact between the rotating shaft and the housing. The sealing device of the present invention has an electrical conduction function (i.e., the sealing device of the present invention functions as an electrical conduction device), and in addition, it also has a sealing function to a certain extent or more. Even when the sealing device of the present invention cannot necessarily ensure the sealing between the rotating shaft and the housing, the electrical conduction between the rotating shaft and the housing is ensured. 【0014】 First, the parts where the sealing device of the present invention can be used will be described with reference to FIGS. 1 and 2. In the following, a plurality of embodiments and the like according to the present invention will be described while referring to the accompanying drawings (FIG. 1, FIG. 2, and other figures). However, the scales of the drawings are not necessarily accurate, and some features may be exaggerated or omitted. 【0015】 As shown in FIG. 1, the power transmission system of an electric vehicle equipped with a sealing device 40 (the sealing device of the present invention) according to an embodiment has an electric motor (motor) 2, a gear train 4, a differential gear device 6, a left axle structure 8, a right axle structure 10, a left drive wheel 12, and a right drive wheel 14. 【0016】 The motor 2 has a stator 16 and a rotor 18, and a rotating shaft 20 is fixed to the rotor 18. The rotating shaft 20 is made of a metal such as cast iron, steel, or aluminum alloy, and is rotatably supported by bearings 21 to 24. The rotation of the rotating shaft 20 is transmitted to the differential gear device 6 by the gear train 4, that is, a gear reducer. The differential gear device 6 rotates the axle structures 8 and 10 while distributing torque to the left and right axle structures 8 and 10 according to the loads acting on the left and right drive wheels 12 and 14. 【0017】 The left axle structure 8 has a shaft 8a, a universal joint 8b, a shaft 8c, a universal joint 8d, and an axle 8e. The shaft 8a is rotated by the differential gear device 6, and the rotation is transmitted to the axle 8e to which the left drive wheel 12 is fixed through the universal joint 8b, the shaft 8c, and the universal joint 8d. The left axle structure 8 is supported by bearings 26 and 27 that rotatably support the shaft 8a and a suspension mechanism 28 that rotatably supports the axle 8e. 【0018】 The right axle structure 10 includes a shaft 10a, a universal joint 10b, a shaft 10c, a universal joint 10d, and an axle 10e. The differential gear device 6 rotates the shaft 10a, and this rotation is transmitted to the axle 10e, to which the right drive wheel 14 is fixed, via the universal joint 10b, shaft 10c, and universal joint 10d. The right axle structure 10 is supported by a bearing 32 that rotatably supports the shaft 10a, and a suspension mechanism 34 that rotatably supports the axle 10e. 【0019】 The motor 2, gear train 4, differential gear 6, and shafts 8a and 10a are housed inside a common housing 38. The housing 38 is made of metal such as cast iron, steel, or aluminum alloy. 【0020】 An annular sealing device 40 is positioned around one end of the rotating shaft 20 of the motor 2, extending across the entire gap between the end 38a of the metal housing 38 and the rotating shaft 20. The sealing device 40 is fixed to the rotating shaft 20 and contacts the inner circumferential surface of the shaft hole in the end 38a of the housing 38. 【0021】 Furthermore, the sealing device 40 according to the above embodiment is arranged around the rotating shaft 20 of the motor 2. However, the sealing device 40 may also be arranged around rotating shafts (shafts 8a, 10a) that are rotated on the rotating shaft 20 of the motor 2 via a power transmission mechanism (for example, a gear train 4 and a differential gear device 6). For example, the sealing device 40 may be arranged in the gap between the housing 38 and shaft 8a, as shown in Figure 2, or in the gap between the housing 38 and shaft 10a. Moreover, the sealing device 40 may be arranged in the gap between the rotating shaft 4A of the intermediate gear of the gear train 4 and the housing 38. Further sealing devices 80, which will be described later, may be arranged near the sealing device 40. 【0022】 Alternatively, the sealing device 40 may be placed in the gap between the rotating shaft of the generator and the housing of the rotating shaft, where lubricating oil is used. Alternatively, the sealing device 40 may be placed in the gap between the rotating shaft that rotates the rotating shaft of the generator and the housing. 【0023】 Instead of the sealing device 40, another sealing device corresponding to the sealing device of the present invention (for example, the sealing device 60 or sealing device 201 described later) can be placed in the same location. 【0024】 The sealing device of the present invention preferably has a sheath tube portion and a conductive portion. Specifically, the sealing device of the present invention preferably has an annular sheath tube portion fixed to the outer surface of the rotating shaft and a conductive portion that is ring-shaped, with the outer circumference of the ring in contact with the inner surface of the housing and the main surface fixed to the sheath tube portion. Preferred embodiments of the sealing device of the present invention will be explained with reference to Figures 3 to 6. 【0025】 The sealing device 40 shown in Figures 3 to 6 corresponds to a preferred embodiment of the sealing device of the present invention. Figures 3 to 6 show a preferred embodiment of the sealing device 40, as well as schematic cross-sectional views (schematic cross-sectional views) of the rotating shaft 20 and housing 38, obtained by cutting across a plane containing the axis ω of the rotating shaft 20. 【0026】 In Figures 3 to 6, the sealing device 40 is positioned in the gap 107 between the outer surface 20s of the rotating shaft 20 and the inner surface 38s that constitutes the shaft hole in the housing 38 into which the rotating shaft 20 is inserted. 【0027】 As mentioned above, an example of a rotating shaft 20 is the motor shaft of a drive motor in an EV (Electric Vehicle) or HEV (Hybrid Electric Vehicle). Typically, the rotating shaft 20 is rod-shaped (cylindrical), and its cross-section is usually circular. 【0028】 Housing 38 is normally grounded. 【0029】 The sealing device 40, which is a preferred embodiment shown in Figures 3 to 6, has a sheath tube portion 110 and a conductive portion 120. 【0030】 <Sheath tube section> The sheath tube portion 110 of the sealing device 40 shown in Figures 3 to 6 will be described below. The sheath tube portion 110 is an annular portion that is directly or indirectly fixed to the outer surface 20s of the rotating shaft 20. In Figures 3, 5, and 6, the sheath tube portion 110 is directly fixed to the outer surface 20s of the rotating shaft 20. In Figure 4, the sheath tube portion 110 is fixed to the outer surface 20s of the rotating shaft 20 via the conductive portion 120, which will be described later. In other words, the sheath tube portion 110 is indirectly fixed to the outer surface 20s of the rotating shaft 20. In the configuration shown in Figure 4, the conductive portion 120 encloses a part of the sheath tube portion 110. 【0031】 The means for fixing the sheath tube portion 110 to the outer surface 20s of the rotating shaft 20 are not particularly limited. For example, the sheath tube portion 110 and the outer surface 20s of the rotating shaft 20 may be fitted together in a tightening-fit manner to fix the sheath tube portion 110 to the outer surface 20s of the rotating shaft 20. Alternatively, the sheath tube portion 110 may be fixed to the outer surface 20s of the rotating shaft 20 using adhesive or the like. 【0032】 The sheath tube portion 110 preferably comprises a fixed portion 110a extending in a direction parallel to the axis ω of the rotation shaft 20, and a support portion 110b connected to the end of the fixed portion 110a and extending toward the inner surface 38s of the housing 38, as shown in Figures 3 to 6. 【0033】 Here, the fixing portion 110a and the support portion 110b are preferably plate-shaped, as shown in the embodiments in Figures 3 to 6. In other words, the fixing portion 110 is preferably cylindrical, and the support portion 110b is preferably disc-shaped with a through hole in the center. Furthermore, it is preferable that the fixed portion 110a and the support portion 110b are substantially perpendicular in a cross-section obtained by cutting with a plane containing the axis ω of the rotation axis 20, as shown in the embodiments in Figures 3 to 6. In the preferred embodiments shown in Figures 3 to 6, the fixed portion 110a and the support portion 110b are substantially perpendicular in the cross-section obtained by cutting with a plane containing the axis ω of the rotation axis 20. Therefore, the sheath tube portion 110 in the preferred embodiments shown in Figures 3 to 6 has a substantially L-shaped cross-section. Here, "approximately vertical" means that it does not have to be perfectly vertical. In other words, in Figures 3 to 6, it is preferable that the fixing part 110a and the support part 110b form a 90-degree angle, but this angle may be 75 to 105 degrees (preferably 80 to 100 degrees, more preferably 85 to 95 degrees). 【0034】 The sheath tube portion 110 is preferably electrically conductive. If the inner circumference 120b of the conductive portion 120, which will be described later, does not come into contact with the outer surface 20s of the rotating shaft 20, the sheath tube portion 110 is always conductive. On the other hand, if the inner circumference 120b of the conductive portion 120, which will be described later, is in contact with the outer surface 20s of the rotating shaft 20, the sheath tube portion 110 does not necessarily need to be conductive. 【0035】 The sheath tube portion 110 is preferably made of metal, and more preferably of a conductive metal. Examples of such metals include stainless steel, cold-rolled steel (SPCC), brass, and aluminum. The sheath tube portion 110 does not have to be made of metal. For example, it may be made of resin. 【0036】 The sheath tube portion 110 can be formed by pressing or forging. 【0037】 The number of sheath tube sections 110 is not limited. For example, in the embodiment shown in Figure 5, two sheath tube sections overlap with the conductive section 120 in between. 【0038】 <Conductive section> The conductive portion 120 of the sealing device 40 shown in Figures 3 to 6 will be described below. The conductive portion 120 is ring-shaped, with its outer circumference 120a in contact with the inner surface 38s of the housing 38, and its main surface 120s fixed to the sheath tube portion 110. As shown in the embodiments in Figures 3 to 6, it is preferable that the main surface 120s of the conductive portion 120 is fixed to the support portion 110b of the sheath tube portion 110. 【0039】 The conductive portion 120 is preferably in the form of a sheet or plate, as shown in the embodiments in Figures 3, 5, and 6, and is flexible or elastic and easily deformable, as will be described later. Figures 3, 5, and 6 show the conductive portion 120 deformed to have a roughly L-shaped cross-section. The main surface 120s of the conductive portion 120 is in contact with the main surface of the plate-shaped support portion 110b in the sheath tube portion 110. It is preferable that the main surface 120s of the conductive portion 120 is in close contact with the main surface of the support portion 110b. Furthermore, the main surface 120s on the outer circumference 120a of the ring is in contact with the inner surface 38a of the housing 38. It is preferable that the rotation of the rotating shaft 20 applies centrifugal force to the sealing device 40, causing the main surface 120s on the outer circumference 120a of the ring to be in close contact with the inner surface 38a of the housing 38. Furthermore, in the embodiment shown in Figure 6, the main surface 120s of the inner circumference 120b of the conductive portion 120 is in contact with the outer surface 20s of the rotating shaft 20. 【0040】 In the conductive portion 120 shown in Figures 3, 5, and 6, which is deformed to have a roughly L-shaped cross-section, the outer ring portion 120a is cylindrical, and the remaining portion is disc-shaped with a through hole in the center. 【0041】 It is preferable that the force pressing the conductive portion 120 against the inner surface 38s of the housing 38 by the centrifugal force F generated by the rotation of the rotating shaft 20 increases compared to before the rotating shaft 20 began to rotate. In the preferred embodiment shown in Figures 3 to 6, when the rotating shaft 20 rotates, a centrifugal force F is applied to the conductive portion 120, and the outer ring portion 120a of the conductive portion 120 is pressed against the inner surface 38s of the housing 38. As a result, the outer ring portion 120a of the conductive portion 120a is stably in close contact with the inner surface 38s of the housing 38, ensuring electrical contact between the rotating shaft 20 and the housing 38. 【0042】 Furthermore, in the preferred embodiments shown in Figures 4 and 6, the inner ring portion 120b of the conductive portion 120 is in contact with the outer surface 20s of the rotating shaft 20. In the preferred embodiments shown in Figures 4 and 6, the outer ring portion 120a of the conductive portion 120 is in contact with the main surface 20s of the rotating shaft 20. It is preferable that the inner circumference 120b of the ring in the conductive portion 120 is in contact with the outer surface 20b of the rotating shaft 20. This is because it facilitates electrical connection between the rotating shaft 20 and the housing 38. In this case, even if the aforementioned sheath tube portion 110 is not conductive, electrical connection is maintained between the rotating shaft 20 and the housing 38. 【0043】 The method for fixing the main surface 120s of the conductive portion 120 to the main surface of the support portion 110b of the sheath tube portion 110 is not particularly limited, and for example, they can be fixed using an adhesive. However, fixing them using metal bolts and nuts without using an adhesive is preferable because it is easier to ensure electrical conductivity between the conductive portion 120 and the sheath tube portion 110, and as a result, electrical conductivity between the rotating shaft 20 and the housing 38 is easier to achieve. 【0044】 The conductive portion 120 is preferably both conductive and flexible. The conductive portion 120 may consist of a rubber material such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), or fluororubber (FKM), and a conductive powder dispersed in the rubber material, such as conductive carbon black powder or metal powder. Furthermore, the conductive portion 120 may be made of a conductive resin such as PTFE. Furthermore, the conductive portion 120 may be a conductive woven fabric or a conductive nonwoven fabric. Examples of materials for conductive nonwoven fabrics or conductive woven fabrics include copper, silver, iron, and carbon. [Explanation of symbols] 【0045】 2. Electric motor 8a, 10a axes (rotation axes) 20 Rotation axis 20s Outer surface of the rotating shaft 38 Housing 38s Housing interior 38b shaft hole 40 Sealing device 41 Cylindrical section 42 Flange 43 Annular section 44 Seal Lip 45 Dust Trip 50 Elastic ring 52 Rigid ring 107 Gap 110 Sheath pipe section 110a Fixing part in the sheath tube section 110b Support part in the sheath tube section 120 Conductive section 120a Outer circumference of the ring in the conductive portion 120b Inner circumference of the ring in the conductive section 120s Main surface of conductive part ω is the axis of rotation.

Claims

[Claim 1] A sealing device that is placed in the gap between the outer surface of a rotating shaft and the inner surface constituting the shaft hole in a housing having a shaft hole into which the rotating shaft is inserted, and that seals this gap, An annular sheath tube portion fixed to the outer surface of the rotating shaft, A conductive portion which is ring-shaped, with the outer circumference of the ring in contact with the inner surface of the housing and the main surface fixed to the sheath tube portion, It has, The inner circumference of the ring of the conductive portion is in contact with the outer surface of the rotating shaft, A sealing device that allows electrical communication between the rotating shaft and the housing, which is pressed against the inner surface constituting the shaft hole in the housing when the rotating shaft rotates. [Claim 2] The sealing device according to claim 1, wherein the centrifugal force generated by the rotation of the rotating shaft increases the force pressing the conductive portion against the inner surface of the housing.

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