Sealing device

Abstract

This invention can suppress the influence of usage conditions and usage time on conductivity, suppress the reduction of sealing performance, reduce sliding resistance, and further improve conductivity. The sealing device (1) includes a reinforcing ring (10), an elastomer portion (20), conductive grease (G), and an annular conductive fabric (30). The elastomer portion (20) has a dustproof lip (21) and a sealing lip (22). The sealing lip (22) has a cylindrical surface, i.e., a lip contact surface (24), formed to contact a shaft. The conductive fabric (30) has an annular inner peripheral contact portion (31) formed to contact a shaft and an annular outer peripheral contact portion (32) formed to contact an outer peripheral component. The conductive grease (G) is provided to be present in at least a portion of the lip contact surface (24) and at least a portion of the sealing lip (22) and the interlip space (S).

Description

Technical Field

[0001] This invention relates to sealing devices, and more particularly to sealing devices for shafts. Background Technology

[0002] In recent years, the electrification of automobiles has been continuously developing, with the development of electric vehicles such as EVs (Electric Vehicles) and HVs (Hybrid Vehicles) progressing steadily. These electric vehicles use a drive motor as a power source, and the induced current generated by this drive motor becomes electromagnetic noise, which can sometimes interfere with AM radios.

[0003] Therefore, there are known vehicle power transmission devices in which a grounding conductive path is formed between a shaft driven by a metal conductive brush and a housing, and leakage current from the drive motor, which is the cause of high-frequency noise, is discharged radially through the conductive path based on the conductive brush into the housing (for example, see Patent Document 1).

[0004] However, in the aforementioned vehicle power transmission device, metal powder is generated by the sliding between the shaft and the conductive brush. Therefore, in order to prevent the metal powder generated from the conductive brush from scattering, a cover is required to prevent scattering, and thus, sufficient space is needed to install the cover.

[0005] In order to save space, an electromagnetic noise suppression device has been proposed. This device is formed by a conductive rubber oil seal that seals the through hole of the housing grounded to the vehicle body and the rotating shaft of the motor. The housing and the rotating shaft are electrically connected through the conductive rubber, thereby releasing the electromagnetic noise induced by the rotating shaft to the metal housing (for example, see Patent Document 2).

[0006] Furthermore, as a sealing device for wheel hub bearings, there exists a bearing seal that uses a sealing lip component made of a rubber material containing conductive carbon to deal with electrical noise (for example, see Patent Document 3).

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: Japanese Patent Application Publication No. 2015-207534

[0010] Patent Document 2: Japanese Patent Application Publication No. 2000-244180

[0011] Patent Document 3: Japanese Patent Application Publication No. 2015-14296 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] In the electromagnetic noise suppression device disclosed in Patent Document 2, although space can be saved, the conductive oil seal may separate from the rotating shaft, for example, if the rotating shaft is eccentric or if the lip end of the conductive oil seal in contact with the rotating shaft becomes loose after prolonged use. As a result, the sealing performance may be reduced, or the electrical noise may not be adequately released into the housing.

[0014] Furthermore, in the sealing device disclosed in the aforementioned Patent Document 3, the generation of electrical noise can be suppressed, but the sliding resistance increases because the conductive lip contacts the hub ring.

[0015] Furthermore, for conventional seals with structures that suppress the effects of electrical noise as described above, there is a need to further improve conductivity.

[0016] Therefore, for seals with conventional structures designed to suppress electrical noise, the following requirements apply: in addition to further improving conductivity, conductivity should not be affected by usage conditions or usage time, and the seal performance should be able to be suppressed and sliding resistance reduced.

[0017] The present invention was made in view of the above-mentioned problems, and its purpose is to provide a sealing device that can suppress the influence of the use state and use time on the conductivity, suppress the reduction of sealing performance, reduce sliding resistance, and further improve the conductivity.

[0018] means for solving problems

[0019] To achieve the above objectives, the sealing device of the present invention seals the annular space between a shaft and an outer peripheral component. The sealing device includes: a reinforcing ring annularly shaped around an axis; an elastomer portion mounted on the reinforcing ring and formed of a conductive elastomer annularly shaped around the axis; a conductive grease; and a conductive fabric annularly shaped around the axis. The elastomer portion has: a dustproof lip extending toward the axis and annularly shaped around the axis; a sealing lip disposed inside the dustproof lip, extending toward the axis, and annularly shaped around the axis; and a gasket portion formed to be able to... The sealing lip has a lip contact surface, which is a cylindrical surface formed to contact the shaft and extend along the axis. The conductive fabric has: an inner peripheral contact portion, which is formed to contact the shaft and is annular about the axis; and an outer peripheral contact portion, which is formed to contact the outer peripheral component and is annular about the axis. The conductive grease is provided to be present in at least a portion of the lip contact surface and at least a portion of the interlip space, which is an annular space between the sealing lip and the dustproof lip.

[0020] In one aspect of the sealing device of the present invention, at least one groove is formed on the lip contact surface, the groove being annular about the axis.

[0021] In a sealing device according to one aspect of the present invention, the elastomer portion has a clamping force applying member, which is an annular elastic member, and the clamping force applying member is configured to apply a clamping force in the sealing lip to press the lip contact surface against the shaft.

[0022] In a sealing device according to one aspect of the present invention, the inner peripheral contact portion of the conductive fabric is formed as a cylindrical shape extending along the axial direction.

[0023] In one aspect of the sealing device of the present invention, the conductive fabric is mounted on the elastomer portion on the outside of the dustproof lip.

[0024] Invention Effects

[0025] The sealing device according to the present invention can suppress the influence of usage conditions and usage time on conductivity, suppress the reduction of sealing performance, reduce sliding resistance, and further improve conductivity. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view along the axis, showing the schematic structure of the sealing device according to an embodiment of the present invention.

[0027] Figure 2 It is Figure 1 The enlarged cross-sectional view of one side of the sealing device shown is a partial enlarged cross-sectional view.

[0028] Figure 3 It is Figure 1 The enlarged cross-sectional view of the interlip space of the elastomer portion in the sealing device shown is a partial enlarged view.

[0029] Figure 4 It means Figure 1 A partially enlarged cross-sectional view of the sealing device in use. Detailed Implementation

[0030] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0031] Figure 1 This is a cross-sectional view along the x-axis, showing the structure of the sealing device 1 according to an embodiment of the present invention. Figure 2 This is a partially enlarged cross-sectional view showing the structure of the sealing device 1 according to an embodiment of the present invention. Figure 2 In, it is shown Figure 1The sealing device 1 shown is on one side (top side) of its cross-section. For ease of explanation, in the x-axis direction, arrow a is designated as the outer side, and arrow b as the inner side. The outer side refers to the atmospheric side where foreign matter such as dust, sand, and mud exists, while the inner side refers to the sealed object space side opposite to the atmospheric side. Furthermore, in the direction perpendicular to the x-axis (hereinafter also referred to as "radial"), the direction away from the x-axis is designated as the outer circumferential side (arrow c direction), and the direction towards the x-axis is designated as the inner circumferential side (arrow d direction).

[0032] The sealing device 1 according to embodiments of the present invention is used to seal the annular space between a shaft (not shown in the figures) and an outer peripheral component, which are inner peripheral components. The sealing device 1, for example, as described later, is used in a motor drive unit of an electric vehicle. In this case, the shaft is the output shaft of an electric motor, and the outer peripheral component is a housing that accommodates the electric motor and has a through hole through which the output shaft of the electric motor passes. Alternatively, the inner peripheral component may be a component that reciprocates along an axis. Furthermore, the object to be sealed by the sealing device 1 is not limited to motor drive units for electric vehicles. For example, the sealing device 1 can also be used in motor drive units of in-wheel motors, motor drive units of hybrid vehicles, motor drive units of electric motorcycles, motor drive units of electric bicycles, and other various other motor drive units.

[0033] like Figure 1 , 2 As shown, the sealing device 1 includes a reinforcing ring 10 arranged in a ring around an axis x, an elastomer portion 20 formed of a conductive elastomer and mounted on the reinforcing ring 10 and arranged in a ring around the axis x, a conductive grease G, and a conductive fabric 30 arranged in a ring around the axis x. Additionally, in Figure 1 The conductive grease G is omitted from the illustration. The elastomer portion 20 includes: a dustproof lip 21 extending toward and annularly around the axis x; a sealing lip 22 disposed on the inner side of the dustproof lip 21 (in the direction of arrow b) extending toward and annularly around the axis x; and a washer portion 23. The washer portion 23 is formed to contact the outer peripheral component in the usage state described later (hereinafter also simply referred to as the "usage state"), where the sealing device 1 is installed in the space between the shaft and the outer peripheral component. The sealing lip 22 has a lip contact surface 24, which is a cylindrical surface extending along the axis x and formed to contact the shaft in the usage state described later. The conductive fabric 30 includes: an inner peripheral contact portion 31, which is formed to contact the shaft and annularly around the axis x in the usage state described later; and an outer peripheral contact portion 32, which is formed to contact the outer peripheral component and annularly around the axis x in the usage state described later. Conductive grease G is provided to be present in at least a portion of the lip contact surface 24 and at least a portion of the interlip space S, which is an annular space between the sealing lip 22 and the dustproof lip 21. The structure of the sealing device 1 will be described in detail below.

[0034] like Figure 1 , 2 As shown, the reinforcing ring 10 is a ring-shaped metal component centered or approximately centered on the axis x, and its cross-section (hereinafter also simply referred to as "cross-section") along the axis x is L-shaped or approximately L-shaped. The reinforcing ring 10 includes, for example, a cylindrical portion 11, which is a cylindrical or approximately cylindrical portion extending along the axis x; and a disc portion 12, which is a hollow disc-shaped portion extending from the outer end (arrow a direction side) of the cylindrical portion 11 towards the inner circumferential side (arrow d direction side). The cylindrical portion 11 is formed such that the sealing device 1 can engage with the inner circumferential surface of the through hole formed in the outer circumferential component (not shown in the figure), and can engage with the inner circumferential surface of the through hole via a portion of the elastic body portion 20. The cylindrical portion 11 can also be formed into a conical ring shape having a step formed midway along the axis x of the cylindrical portion 11, and a portion of the cylindrical portion 11 can directly engage with the inner circumferential surface of the through hole in the use state.

[0035] like Figure 1 , 2 As shown, the elastomer portion 20 is mounted on the reinforcing ring 10, and in this embodiment, it is integrally formed with the reinforcing ring 10 in a manner that covers the entire reinforcing ring 10. As described above, the elastomer portion 20 has a dustproof lip 21, a sealing lip 22 disposed inside the dustproof lip 21, and a gasket portion 23. In addition, the elastomer portion 20 has an annular lip waist portion 25 and a cover portion 26. The lip waist portion 25 is the portion located near the end of the inner circumferential side of the disc portion 12 in the reinforcing ring 10. The cover portion 26 is the portion mounted to the disc portion 12 from the outside and the inside between the lip waist portion 25 and the gasket portion 23.

[0036] The dustproof lip 21 extends obliquely outward from the lip waist 25 toward the axis x, and has a shape that narrows as it moves outward. The front end portion of the dustproof lip 21, namely the front end portion 21a of the dustproof lip, is formed such that, in the use state of the sealing device 1, the shaft can slide into contact with the surface of the outer peripheral side of the shaft.

[0037] The sealing lip 22 is located inside the dustproof lip 21 and extends inward along the axis x from the lip waist 25. Furthermore, the front end portion of the sealing lip 22, i.e., the sealing lip front end portion 22a, is a ring-shaped portion protruding towards the inner circumference. The cross-sectional shape of the sealing lip front end portion 22a is, for example, as shown below. Figure 2 The shape is approximately rectangular or approximately trapezoidal. The front end 22a of the sealing lip is formed such that the shaft can slide in contact with the outer peripheral surface of the shaft when the sealing device 1 is in use. Specifically, as shown... Figure 2 As shown, the sealing lip front end 22a has a lip contact surface 24 on the inner circumferential side, which is a cylindrical surface. In the use state, the sealing lip front end 22a is formed such that the shaft can slide freely in contact with the outer circumferential surface of the shaft on the lip contact surface 24.

[0038] The lip contact surface 24 is a cylindrical surface, for example, Figure 2 As shown, it is a cylindrical surface or approximately cylindrical surface with axis x as its central axis or approximately central axis. At least one annular groove 27 is formed on the lip contact surface 24 around axis x. In this embodiment, as... Figure 1 , 2 As shown, three grooves 27 are formed. The grooves 27 are seamless annular grooves, for example, grooves extending in an annular or approximately annular shape centered on or approximately centered on the axis x. Additionally, the grooves 27 form a space recessed from the lip contact surface 24 towards the outer periphery. The number of grooves 27 formed on the lip contact surface 24 is not limited to the above-described number. Furthermore, the shape of the grooves 27 is not limited to the shapes described above. The grooves 27 can also be formed by one or more arc-shaped grooves. For example, the grooves 27 can also be formed by multiple arc-shaped grooves spaced apart and arranged in an annular shape.

[0039] Additionally, the elastomer portion 20 includes a clamping force applying member 28, which is an annular elastic member. The clamping force applying member 28 is configured to apply a clamping force to the sealing lip 22 in use, pressing the lip contact surface 24 against the shaft. Specifically, the clamping force applying member 28 is a retaining spring 28, which is fitted into a recess 22b formed in the sealing lip 22. The recess 22b is a portion recessed towards the inner circumference and is located in the sealing lip 22 at a position opposite to the front end portion 22a of the sealing lip on the outer circumference side. The retaining spring 28 is, for example, a coil-shaped spring member made of metal, which pushes the front end portion 22a of the sealing lip in the direction toward the axis x, applying a clamping force of a predetermined magnitude relative to the shaft to the front end portion 22a of the sealing lip in such a way that the displacement of the lip contact surface 24 of the front end portion 22a relative to the shaft follows the outer circumferential surface of the shaft. Furthermore, the retaining spring 28 is not limited to being made of metal and can also be formed of various other materials such as resin.

[0040] The washer portion 23 is mounted on the cylindrical portion 11 of the reinforcing ring 10 in such a way that it surrounds the cylindrical portion 11 of the reinforcing ring 10 from both the outer and inner circumferential sides. It has an outer circumferential washer portion 23a covering the cylindrical portion 11 from the outer circumferential side and an inner circumferential washer portion 23b covering the cylindrical portion 11 from the inner circumferential side. The outer circumferential washer portion 23a has a radial thickness such that when the sealing device 1 is pressed into the inner circumferential surface (through hole) of the outer circumferential component, it is radially compressed between the through hole and the cylindrical portion 11 of the reinforcing ring 10, generating a predetermined engagement force, which is a radial force. The cylindrical portion 11 of the reinforcing ring 10 and the washer portion 23 of the elastomer portion 20 are respectively formed such that when the sealing device 1 is fitted into the through hole of the outer circumferential component, the axis x of the sealing device 1 is aligned with the axis of the shaft.

[0041] The conductive elastomer of the elastomer portion 20 can be, for example, a conductive rubber containing conductive fillers such as carbon black particles or metal powder. Such a conductive rubber, containing conductive fillers, has relatively low resistance. The volume resistivity of the conductive rubber is, for example, 10⁻⁶. 8 Below Ω·cm. More specifically, conductive rubber is formed by mixing any rubber material, conductive particles, and conductive fibers in desired amounts. Examples of rubber materials include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), fluororubber (FKM), and silicone rubber. Conductive particles, in addition to carbon black, can also be conductive metal oxides such as graphite, indium / tin oxide, and antimony / tin oxide. These materials can also be selected appropriately. Conductive fibers include stainless steel fibers, carbon fibers (carbon fibers, carbon nanotubes), or conductive fibers plated in potassium titanate. Furthermore, the thickness and length of the conductive fibers can be arbitrarily selected.

[0042] The metal material for the reinforcing ring 10 can be, for example, stainless steel or SPCC (cold-rolled steel). The reinforcing ring 10 is manufactured, for example, by stamping or forging, and the elastomer portion 20 is formed using a forming die through cross-linking (vulcanization). During this cross-linking process, the reinforcing ring 10 is disposed in the forming die, and the elastomer portion 20 is bonded to the reinforcing ring 10 through cross-linking bonding, thus the elastomer portion 20 and the reinforcing ring 10 are integrally formed.

[0043] Furthermore, as described above, the sealing device 1 is provided with conductive grease G, which is present in at least a portion of the lip contact surface 24 and at least a portion of the interlip space S, the interlip space S being an annular space between the sealing lip 22 and the dustproof lip 21. For example, as... Figure 3 As shown, conductive grease G adheres to the bottom surface 29 that forms the interlip space S. The bottom surface 29 is along... Figure 3 The surface extending from the imaginary line l shown is formed by the surfaces facing the inner circumferential sides of the sealing lip 22, the lip waist 25, and the dustproof lip 21, respectively. Specifically, the bottom surface 29 is the surface facing the inner circumferential side extending between the outer end (outer end 24a) of the lip contact surface 24 of the sealing lip front end 22a and the dustproof lip front end 21a of the dustproof lip 21. (As shown...) Figure 3 As shown, the bottom surface 29 is a surface that is concave to the outer periphery. The interlip space S is an annular space surrounded by the bottom surface 29, and the boundary B on the inner periphery is a conical or cylindrical surface that extends between the outer end 24a of the lip contact surface 24 and the front end 21a of the dustproof lip 21.

[0044] The conductive grease G is applied to the bottom surface 29 in such a way that it fills at least a portion of the interlip space S, for example, as shown in the image. Figure 3As shown in the example, the conductive grease G is arranged in a manner that does not completely fill the interlip space S. The conductive grease G can be arranged to partially fill the interlip space S, completely fill the interlip space S, or overflow from the interlip space S. Alternatively, the conductive grease G can be arranged to protrude from the interlip space S.

[0045] Additionally, a portion of the lip contact surface 24 of the sealing lip 22 is also coated with conductive grease G. For example, such as... Figure 3 As shown, conductive grease G adheres to the entire lip contact surface 24. The conductive grease G is adhered in a manner that fills the groove 27. The conductive grease G can be provided in a manner that covers a portion of the lip contact surface 24 as described above, or in a manner that covers the entire lip contact surface 24, or in a manner that exposes from the lip contact surface 24.

[0046] Conductive grease G can be any type of grease containing a conductive substance. There are no particular limitations on the base oil used in conductive grease G; any type of oil can be used as a base oil. Furthermore, any conductive substance is acceptable; there are no particular restrictions on its conductivity. Preferably, substances with good conductivity are preferred. The conductive substance can be a liquid or a solid. For example, carbon black is a conductive substance. The volume resistivity of conductive grease G is, for example, 10⁻⁶. 8 Below Ω·cm.

[0047] Additionally, as described above, the sealing device 1 includes a conductive fabric 30. The conductive fabric 30 is a component formed from conductive fibers, such as a woven fabric or nonwoven fabric made of conductive fibers. Examples of conductive fibers include stainless steel fibers, carbon fibers (carbon fibers, carbon nanotubes), or conductive fibers plated in potassium titanate. The conductive fabric 30 has: an inner peripheral contact portion 31, which is formed to contact the shaft in a manner that allows the shaft to slide in the operating state; and an outer peripheral contact portion 32, which is formed to contact an outer peripheral component.

[0048] Specifically, such as Figure 1 , 2As shown, the conductive fabric 30 is in the shape of a hollow disk, for example, having a disk portion 33 that extends between the inner peripheral contact portion 31 and the outer peripheral contact portion 32. The disk portion 33 is a portion having an annular shape extending radially in a flat or substantially flat shape, having an inner surface 33a and an outer surface 33b, which are a pair of annular surfaces facing away from each other. The inner peripheral contact portion 31 extends in a cylindrical shape from the outer surface 33b at its inner peripheral end (inner peripheral end 33c) of the disk portion 33, and the outer peripheral contact portion 32 extends in a cylindrical shape from the outer surface 33b at its outer peripheral end (outer peripheral end 33d) of the disk portion 33.

[0049] For example, the inner peripheral contact portion 31 Figure 2 The device is formed in a cylindrical or substantially cylindrical shape with the axis x as its central axis or approximately its central axis, and a flange is formed at the inner peripheral end 33c. The inner peripheral contact portion 31 has a contact surface 31a, which is an annular surface facing the inner peripheral side. The contact surface 31a is shaped such that the shaft can slide against the contact surface in the use state. The contact surface 31a is, for example, a cylindrical or substantially cylindrical surface with the axis x as its central axis or approximately its central axis. In this case, the contact surface 31a of the inner peripheral contact portion 31 is a cylindrical surface, thus increasing the contact area with the shaft. In addition, since the inner peripheral contact portion 31 is formed in a flange shape, it is easier to follow the outer peripheral surface of the shaft when it is eccentric with respect to the shaft in the use state.

[0050] For example, the peripheral contact portion 32 Figure 2 The portion shown is cylindrical or substantially cylindrical with the axis x as its central axis or approximately its central axis, and a flange is formed at the outer peripheral end 33d. The outer peripheral contact portion 32 has a contact surface 32a, which is an annular surface facing the outer peripheral side. The contact surface 32a is shaped to contact the inner peripheral surface of the through hole of the outer peripheral component in the use state. The contact surface 32a is, for example, a cylindrical or substantially cylindrical surface with the axis x as its central axis or approximately its central axis. In this case, the contact surface 32a of the outer peripheral contact portion 32 is a cylindrical surface, thus increasing the contact area with the through hole of the outer peripheral component.

[0051] The inner peripheral contact portion 31 can be any shape that allows it to contact the shaft in the usage state, or it can be any other shape. Similarly, the outer peripheral contact portion 32 can be any shape that allows it to contact the outer peripheral component in the usage state, or it can be any other shape. Furthermore, the conductive fabric 30 may not have the inner peripheral contact portion 31, and may instead be formed to contact the shaft at the inner peripheral end 33c of the disk portion 33. The conductive fabric 30 may also not have the outer peripheral contact portion 32, and may instead contact the outer peripheral component at the outer peripheral end 33d of the disk portion 33. Additionally, the conductive fabric 30 may not have the outer peripheral contact portion 32, and may not contact the outer peripheral component at the outer peripheral end 33d of the disk portion 33.

[0052] The conductive fabric 30 is fixed to the elastomer portion 20 by adhesive or the like. The conductive fabric 30 is attached to the elastomer portion 20 on the outside of the dustproof lip 21, for example... Figure 1 , 2 As shown, the inner surface 33a of the disc portion 33 is fixed to the cover portion 26 of the elastomer portion 20. Therefore, in the sealing device 1, the inner peripheral contact portion 31 and the outer peripheral contact portion 32 of the conductive fabric 30 extend outward. Furthermore, as described above, the conductive fabric 30 is fixed to the elastomer portion 20 such that, in the use state, the inner peripheral contact portion 31 and the outer peripheral contact portion 32 are in contact with the shaft and the outer peripheral component, respectively. The inner peripheral contact portion 31 and the outer peripheral contact portion 32 are fixed in a manner that does not interfere with the elastomer portion 20. Since the conductive fabric 30 is fixed to the elastomer portion 20 at the cover portion 26, the contact area between the conductive fabric 30 and the elastomer portion 20 can be increased.

[0053] The inner peripheral contact portion 31 and the outer peripheral contact portion 32 may extend in different directions relative to the disk portion 33, and both the inner peripheral contact portion 31 and the outer peripheral contact portion 32 may extend inward.

[0054] Next, the function of the sealing device 1 having the above structure will be explained. Figure 4 This is a partially enlarged cross-sectional view of the sealing device 1 in its operational state. Figure 4 This is an example of the usage state of the sealing device 1, which is installed in the motor drive unit 100 of an electric vehicle and is thus in use. For example... Figure 4 As shown, in use, the sealing device 1 is installed between the output shaft 102 and the opening 104 to seal the annular gap between the output shaft 102 of the electric motor 101 and the opening 104. The opening 104 forms a through hole 105 for the output shaft 102 to pass through. The opening 104 is formed in the housing 103 of the motor drive device 100, the electric motor 101 is housed in the housing 103, and the output shaft 102 is supported by a bearing (not shown in the figure).

[0055] Lubricating oil is sealed inside the housing 103. The sealing device 1 prevents the lubricating oil inside the housing 103 from leaking to the outside, and also prevents foreign objects such as dust, sand, mud and water from entering the housing 103.

[0056] like Figure 4 As shown, in use, the sealing device 1 is pressed into and installed in the opening 104 of the housing 103. The washer portion 23 of the elastomer portion 20 contacts the inner circumferential surface 104a of the opening 104, and is compressed between the opening 104 and the reinforcing ring 10. Thus, the sealing device 1 is sealed between itself and the opening 104 of the housing 103. Furthermore, the sealing lip tip 22a of the sealing lip 22 contacts the outer circumferential surface 102a of the output shaft 102 at the lip contact surface 24, allowing the output shaft 102 to slide, thereby sealing the sealing device 1 between itself and the output shaft 102.

[0057] In the operating state, the sealing lip 22 and dustproof lip 21 of the elastomer portion 20 contact the outer peripheral surface 102a of the output shaft 102 at the lip contact surface 24 and the front end 21a of the dustproof lip, respectively, forming a closed space (lip space S) between the bottom surface 29 and the outer peripheral surface 102a of the output shaft 102. Through this contact, the sealing lip 22 and dustproof lip 21 deform, and in the operating state, the lip space S deforms. In the operating state, the volume of the lip space S is smaller than the volume of the lip space S in the sealing device 1 in its free state when not installed on the motor drive device 100. Furthermore, in the operating state, the sealing lip 22 and dustproof lip 21 may not deform, or either one may remain undeformed.

[0058] As described above, the lip contact surface 24 forms an annular surface, becoming a cylindrical or approximately cylindrical surface extending along the x-axis. Therefore, the lip contact surface 24 contacts the outer peripheral surface 102a of the output shaft 102 with a large width in the x-axis direction. Furthermore, the lip contact surface 24 is subjected to a clamping force relative to the output shaft 102 by a clamping spring 28. Therefore, even in the case of eccentricity of the output shaft 102, the lip contact surface 24 follows the outer peripheral surface 102a of the output shaft 102 by the clamping spring 28, maintaining a large contact area.

[0059] As described above, the conductive grease G is attached to the bottom surface 29 of the sealing device 1 in a manner that fills a portion of the interlip space S. In the operating state, at least a portion of the bottom surface 29 is connected to a portion of the outer peripheral surface 102a of the output shaft 102 via the conductive grease G. The conductive grease G may also be attached to the bottom surface 29 of the sealing device 1 in a manner that fills the interlip space S of the sealing device 1 in the operating state. Figure 4 In the example, in the sealing device 1 under use, the interlip space S is filled with conductive grease G.

[0060] Furthermore, it is preferable to set the amount of conductive grease G adhering to the bottom surface 29 of the sealing device 1 in such a way that the volume of the conductive grease G is larger than the volume of the interlip space S, so that the conductive grease G does not expand during use. This is to prevent the conductive grease G from expanding during use and becoming larger than the volume of the interlip space S. As a result, it is possible to prevent the sealing lip 22 from floating up and releasing the contact between the lip contact surface 24 and the outer peripheral surface 102a of the output shaft 102. Similarly, it is possible to prevent the contact between the dustproof lip 21 and the outer peripheral surface 102a of the output shaft 102 from being released. Therefore, in the free state of the sealing device 1, the amount of conductive grease G adhering to the bottom surface 29 is preferably an amount that does not completely fill the interlip space S.

[0061] Furthermore, as described above, in the free state of the sealing device 1, conductive grease G is also adhered to the lip contact surface 24 of the sealing lip 22. Therefore, in the operating state, the conductive grease G is located between the lip contact surface 24 of the sealing lip 22 and the outer peripheral surface 102a of the output shaft 102. Figure 4 In the example, the conductive grease G is located between the entire surface of the lip contact surface 24 of the sealing lip 22 and the outer peripheral surface 102a of the output shaft 102. Therefore, in the free state of the sealing device 1, the conductive grease G adheres to the entire surface or substantially the entire surface of the lip contact surface 24 of the sealing lip 22. Furthermore, in the operating state, the conductive grease G may not be located between the entire surface of the lip contact surface 24 and the outer peripheral surface 102a of the output shaft 102, or it may be located between a portion of the lip contact surface 24 and the outer peripheral surface 102a of the output shaft 102. Therefore, in the free state of the sealing device 1, the conductive grease G may not adhere to the entire surface of the lip contact surface 24 of the sealing lip 22.

[0062] In addition, such as Figure 4 As shown, in the operating state, conductive grease G is also present in the groove 27 of the lip contact surface 24. Figure 4 In the example, conductive grease G is present throughout the groove 27 of the lip contact surface 24. The conductive grease G may also not be present throughout the groove 27 of the lip contact surface 24.

[0063] In addition, in use, the inner peripheral contact portion 31 of the conductive fabric 30 contacts the outer peripheral surface 102a of the output shaft 102 on the cylindrical or substantially cylindrical contact surface 31a, and the outer peripheral contact portion 32 of the conductive fabric 30 contacts the inner peripheral surface 104a of the opening 104 of the housing 103 on the cylindrical or substantially cylindrical contact surface 32a.

[0064] As described above, in use, the sealing device 1 electrically connects the output shaft 102 and the housing 103 via an elastomer portion 20 formed of conductive rubber, ensuring conductivity between the output shaft 102 and the housing 103. Thus, the elastomer portion 20 forms a conductive path electrically connecting the output shaft 102 and the housing 103 in use. Therefore, leakage current generated in the electric motor 101 can be discharged from the output shaft 102 to the housing 103, suppressing noise generation.

[0065] Furthermore, as described above, the lip contact surface 24 of the sealing lip 22 is a cylindrical or substantially cylindrical surface extending along the axis x, thus the lip contact surface 24 contacts the output shaft 102 with a large width in the axis x direction. Therefore, the lip contact surface 24 can improve the conductivity of the conductive path formed by the elastomer portion 20. As a result, the amount of leakage current generated in the electric motor 101 can be increased from the output shaft 102 to the housing 103, and the generation of noise can be further suppressed.

[0066] Furthermore, the clamping force of the clamping spring 28 causes the lip contact surface 24 to follow the output shaft 102, maintaining the posture of the lip contact surface 24 relative to the outer peripheral surface 102a of the output shaft 102. Therefore, even in cases of eccentricity of the output shaft 102, the reduction of the contact area of ​​the lip contact surface 24 relative to the outer peripheral surface 102a of the output shaft 102 can be suppressed. As a result, a large contact area of ​​the lip contact surface 24 relative to the outer peripheral surface 102a of the output shaft 102 can be stably maintained during use, the conductivity of the conductive path formed by the elastomer portion 20 can be stably maintained, and noise generation can be stably suppressed.

[0067] Furthermore, as described above, in use, the sealing device 1 electrically connects the output shaft 102 and the housing 103 via the conductive fabric 30, ensuring conductivity between the output shaft 102 and the housing 103. Thus, in use, the conductive fabric 30 forms a conductive path that electrically connects the output shaft 102 and the housing 103. Therefore, in addition to the elastomer portion 20, the conductive fabric 30 can also discharge leakage current generated in the electric motor 101 from the output shaft 102 to the housing 103, thereby further suppressing noise generation.

[0068] Thus, in addition to the conductive path formed by the elastomer portion 20, the sealing device 1 also has a conductive path formed by the conductive fabric 30. Therefore, the conductivity between the output shaft 102 and the housing 103 can be increased, and the conductivity of the sealing device 1 can be improved. As a result, the amount of leakage current generated in the electric motor 101 can be increased from the output shaft 102 to the housing 103, and the generation of noise can be further suppressed.

[0069] Furthermore, when the contact area between the inner peripheral contact portion 31 of the conductive fabric 30 and the outer peripheral surface 102a of the output shaft 102 is reduced due to eccentricity of the output shaft 102, or when the contact area between the inner peripheral contact portion 31 and the outer peripheral surface 102a of the output shaft 102 is reduced due to deformation of the conductive fabric 30 caused by use, the conductivity of the conductive path formed by the conductive fabric 30 decreases. However, since the sealing device 1 has a conductive path formed by the elastomer portion 20, it can maintain the conductivity of the sealing device 1 as a whole, and can maintain the function of suppressing noise generation regardless of the usage conditions or usage time.

[0070] Furthermore, since the inner peripheral contact portion 31 of the conductive fabric 30 is formed in a flange shape, it easily follows the outer peripheral surface 102a of the output shaft 102 even when eccentric relative to the output shaft 102 during use. Additionally, since the contact surface 31a of the inner peripheral contact portion 31 of the conductive fabric 30 is a cylindrical or substantially cylindrical surface, the contact area with the outer peripheral surface 102a of the output shaft 102 is increased. Furthermore, since the contact surface 32a of the outer peripheral contact portion 32 is a cylindrical or substantially cylindrical surface, the contact area with the inner peripheral surface 104a of the opening 104 is increased. Moreover, since the conductive fabric 30 is fixed to the elastomer portion 20 at the cover portion 26, the contact area between the conductive fabric 30 and the elastomer portion 20 is increased. Therefore, the conductive fabric 30 can increase conductivity, thereby effectively suppressing noise generation. Furthermore, it can stably maintain conductivity regardless of usage conditions, thereby stably maintaining the noise suppression effect.

[0071] In addition, conductive grease G is provided in the lip space S and the lip contact surface 24 of the sealing lip 22 of the sealing device 1. In use, the conductive grease G is located between the elastomer portion 20 and the output shaft 102. The conductive grease G reduces the resistance between the output shaft 102 and the housing 103, thereby further reducing noise generation.

[0072] In addition, the sealing device 1 has two lips, a sealing lip 22 and a dustproof lip 21. However, since conductive grease G is provided on the lip contact surface 24 and the lip space S, the sliding resistance can be reduced by the lubrication of the grease, and the increase in sliding resistance caused by the increase in the number of lips can be suppressed.

[0073] Furthermore, the lip contact surface 24 of the sealing lip 22 has a large contact area. Additionally, there is a concern that the sliding resistance generated by the sealing lip 22 might increase when a clamping force is applied by the clamping spring 28. However, as described above, a groove 27 is formed in the lip contact surface 24, which reduces the contact area of ​​the lip contact surface 24 while ensuring its width in the x-axis direction to maintain a stable posture. Therefore, the increase in sliding resistance caused by the sealing lip 22 can be suppressed. Furthermore, in use, conductive grease G can be retained within the groove 27, and the lubrication of the grease can reduce the sliding resistance, further suppressing the increase in sliding resistance caused by the sealing lip 22.

[0074] As described above, the lip contact surface 24 has an annular surface facing the outer peripheral surface 102a of the output shaft 102. Therefore, according to the sealing device 1, unlike conventional sealing devices, such as those with a wedge-shaped lip tip, the deformation of the sealing lip tip 22a when in contact with the outer peripheral surface 102a of the output shaft 102 is minimal. That is, the sealing lip 22 of the sealing device 1 has excellent durability and can increase the contact area with the output shaft 102.

[0075] In addition, as mentioned above, the sealing device 1 itself is conductive, so there is no need to prepare a metal brush or the like in order to achieve the connection between the output shaft 102 and the housing 103, which simplifies the structure of the motor drive device 100 and saves space in the motor drive device 100.

[0076] In addition, in the sealing device 1, even when the rubber of the elastomer part 20 is cured in a low temperature environment such as below 0°C, the clamping force of the clamping spring 28 can be used to press the lip contact surface 24 forcefully against the outer peripheral surface 102a of the output shaft 102. Therefore, the conductive state between the output shaft 102 and the housing 103 can be maintained, and the generation of noise can be stably reduced even in a low temperature environment.

[0077] Furthermore, in the sealing device 1, when the sealing lip 22 of the elastomer portion 20 becomes loose or wears down after prolonged use, the contact area between the lip contact surface 24 of the sealing lip front end 22a and the outer peripheral surface 102a of the output shaft 102 may be partially reduced. Even in such cases, in the sealing device 1, the posture of the lip contact surface 24 of the elastomer portion 20 relative to the outer peripheral surface 102a of the output shaft 102 is stabilized by the clamping force of the clamping spring 28. In addition, the lip contact surface 24 of the sealing lip 22 is kept firmly pressed against the outer peripheral surface 102a of the output shaft 102. Therefore, regardless of the usage time, the conduction state between the output shaft 102 and the housing 103 can be maintained, and the generation of noise is steadily reduced.

[0078] As described above, the sealing device 1 according to the embodiments of the present invention can suppress the influence of usage conditions and usage time on conductivity, suppress the reduction of sealing performance, reduce sliding resistance, and further improve conductivity.

[0079] The sealing device 1 according to the embodiments of the present invention has been described above. However, the sealing device according to the present invention is not limited to the sealing device 1 described above, but includes all the concepts of the present invention and all the embodiments included in the claims. In addition, in order to solve or achieve at least some of the above-mentioned problems and effects, the various structures may be appropriately and selectively combined. For example, the shape, material, arrangement, size, etc. of each component in the above embodiments can be appropriately changed according to the specific usage of the present invention.

[0080] Symbol Explanation

[0081] 1…Sealing device

[0082] 10…Reinforcing ring

[0083] 11…Cylindrical section

[0084] 12…Disc section

[0085] 20…Elastomer section

[0086] 21… Dustproof Lips

[0087] 21a… Dustproof lip front end

[0088] 22…Sealing Lip

[0089] 22a… sealing lip front end

[0090] 22b…concave part

[0091] 23…Washer section

[0092] 23a…Outer peripheral washer portion

[0093] 23b…Inner circumferential washer portion

[0094] 24…lip contact surface

[0095] 24a…outer end

[0096] 25…lips and waist

[0097] 26…covering

[0098] 27… slots

[0099] 28…Clamping spring (component for applying clamping force)

[0100] 29…Bottom

[0101] 30…conductive fabric

[0102] 31…Inner peripheral contact area

[0103] 31a…Contact Surface

[0104] 32…peripheral contact area,

[0105] 32a…Contact Surface

[0106] 33…Disc section

[0107] 33a…inner side

[0108] 33b…outer side

[0109] 33c…Inner circumferential end

[0110] 33d…peripheral end

[0111] 100…motor drive unit

[0112] 101… Electric Motor

[0113] 102… Output shaft

[0114] 102a…outer peripheral surface

[0115] 103…outer shell

[0116] 104…Opening

[0117] 104a…inner circumferential surface

[0118] 105… Through hole

[0119] B…boundary

[0120] G…conductive grease

[0121] S…lip space

[0122] x…axis

Claims

1. A sealing device for sealing an annular space between a shaft and an outer peripheral component, the sealing device being characterized by comprising: A reinforcing ring that is looped around the axis; The elastomer portion is mounted on the reinforcing ring and is formed of a conductive elastomer that is annular around the axis. Conductive grease; as well as A conductive fabric arranged in a ring around the axis. The elastomer portion has: A dustproof lip extends toward the axis and is looped around the axis; A sealing lip, disposed inside the dustproof lip and extending toward the axis, and forming a ring around the axis; and The washer portion is configured to contact the outer peripheral component. The sealing lip has a lip contact surface that is configured to contact the shaft. The lip contact surface is a cylindrical surface extending along the axis in the free state when the sealing device is not installed in the space between the shaft and the outer peripheral component. The conductive fabric has: The inner peripheral contact portion is formed to be able to contact the shaft and to be annular around the axis; as well as The outer peripheral contact portion is a portion formed to contact the outer peripheral component and to be annular around the axis. The conductive grease is configured to exist in at least a portion of the lip contact surface and at least a portion of the interlip space in the free state, the interlip space being an annular space between the sealing lip and the dustproof lip.

2. The sealing device as claimed in claim 1, characterized in that, At least one groove is formed on the lip contact surface, and the groove is annular around the axis.

3. The sealing device as described in claim 1, characterized in that, The elastic body portion has a clamping force applying component, which is a ring-shaped elastic component. The clamping force applying component is configured to apply a clamping force in the sealing lip to press the lip contact surface against the shaft.

4. The sealing device as described in claim 2, characterized in that, The elastic body portion has a clamping force applying component, which is a ring-shaped elastic component. The clamping force applying component is configured to apply a clamping force in the sealing lip to press the lip contact surface against the shaft.

5. The sealing device according to any one of claims 1 to 4, characterized in that, The inner peripheral contact portion of the conductive fabric is formed into a tubular shape extending along the axial direction.

6. The sealing device according to any one of claims 1 to 4, characterized in that, The conductive fabric is attached to the elastomer portion on the outside of the dustproof lip.

7. The sealing device as claimed in claim 5, characterized in that, The conductive fabric is attached to the elastomer portion on the outside of the dustproof lip.

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