Conductive sealing device

Abstract

To provide a sealing device which can maintain conductivity with respect to even an internal peripheral side member which rotates at a high speed.SOLUTION: A sealing device (1) comprises a conductive elastic body part (2) being an annular member, and having a portion which is formed of an elastic material having conductivity. The conductive elastic body part (2) can contact with a shaft (101) of an electric motor and a housing (102). In the conductive elastic body part (2), a conductive circuit (3) can be formed between the shaft (101) of the electric motor and the housing (102). An impedance of the conductive circuit (3) at the rotation of the shaft (101) of the electric motor whose peripheral speed is equal to or lower than 60 m / s is equal to or higher than 0.01 Ω, and equal to or lower than 100 Ω.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to an electrically conductive sealing device. [Background technology]

[0002] For example, in a vehicle equipped with an electric motor such as an electric vehicle (EV), electromagnetic noise may be generated by induced currents generated by the motor. Such electromagnetic noise may cause communication problems in AM radios and other wireless communication devices. In addition, such electromagnetic noise may cause electrolytic corrosion in metal parts such as bearings. For this reason, efforts have been made to remove such electromagnetic noise. For example, a technology has been disclosed in which an oil seal that seals the rotating shaft of a motor is made of conductive rubber, and electromagnetic noise is released from the rotating shaft to a housing (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2000-244180 A Summary of the Invention [Problem to be solved by the invention]

[0004] For conventional oil seals that have such conductive rubber, which are intended to address problems caused by electromagnetic noise, there is a demand for a configuration that can maintain conductive performance even when the shaft is rotating at higher speeds.

[0005] An object of the present invention is to provide a sealing device that can maintain electrical conductivity even when an inner peripheral member rotates at high speed. [Means for solving the problem]

[0006] In order to solve the above problems, the sealing device of the present invention is a sealing device for sealing an annular space between an inner side member and an outer side member which rotate relative to each other, and is characterized in that it comprises a conductive elastic body part which is an annular member around an axis and has a portion formed from an elastic material having conductivity, the conductive elastic body part is capable of contacting the inner side member and the outer side member and is capable of forming a conductive circuit between the inner side member and the outer side member, and the impedance of the conductive circuit during the relative rotation at a peripheral speed of 60 m / s or less is 0.01 Ω or more and 100 Ω or less.

[0007] In a sealing device according to one embodiment of the present invention, the conductive circuit is configured to maintain electrical contact with the inner side member even when subjected to a force that causes contact between the conductive elastic body portion and the inner side member to be broken based on the relative rotation.

[0008] In the sealing device according to one aspect of the present invention, the conductive elastic body portion has heat resistance of -40° or more and 200° or less.

[0009] In a sealing device according to one embodiment of the present invention, the conductive elastic body portion has an annular conductive lip around the axis that is formed so as to be in contact with the inner peripheral member, and the sealing device further has a conductive lubricant interposed between the conductive lip and the inner peripheral member.

[0010] In a sealing device according to one embodiment of the present invention, the conductive lip has at least one groove for retaining the lubricant, the groove being annular about the axis and formed in a portion of the conductive lip that contacts the inner peripheral member.

[0011] A sealing device according to one embodiment of the present invention further includes a sealing device main body which is an annular member around the axis for sealing the annular space, and the conductive elastic body is attachable to the sealing device main body.

[0012] In a sealing device according to one embodiment of the present invention, the conductive elastic body portion has a ring-shaped reinforcing ring and a main body portion formed from the conductive elastic material attached to the reinforcing ring, and the main body portion has a ring-shaped conductive lip around the axis formed so as to be able to contact the inner side member, and the conductive lip is provided on the inner side of the inner portion of the reinforcing ring. Effect of the Invention

[0013] According to the sealing device of the present invention, electrical conductivity can be maintained even with respect to an inner peripheral member rotating at high speed. [Brief description of the drawings]

[0014] [Figure 1] 1 is a partial cross-sectional view of a sealing device according to a first embodiment of the present invention, which is disposed in an annular space between an inner peripheral side member and an outer peripheral side member which rotate relatively to each other. [Diagram 2] FIG. 2 is a partial perspective view of the sealing device shown in FIG. [Diagram 3] 4 is a diagram showing a part of the contact surface of the conductive lip as viewed from the inner circumferential side. FIG. [Figure 4] 4A and 4B are cross-sectional views of the conductive lip, FIG. 4A being a cross-sectional view taken along line AA in FIG. 3, and FIG. 4B being a cross-sectional view taken along line BB in FIG. [Diagram 5] 1. FIG. 4 is a diagram showing a thread projection as a modified example of the thread groove of the sealing device shown in FIG. [Figure 6] 1 is a graph showing electrical conductivity performance versus circumferential speed of a rotating shaft of a sealing device according to an embodiment of the present invention; [Figure 7] FIG. 2 is a diagram showing an example of an impedance measuring device for measuring the impedance of a conductive circuit of a sealing device. [Figure 8] 6 is a partial cross-sectional view of a sealing device according to a second embodiment of the present invention, which is disposed in an annular space between an inner peripheral side member and an outer peripheral side member which rotate relatively to each other. FIG. [Figure 9] FIG. 9 is a partial perspective view of the sealing device shown in FIG. 8. [Figure 10]11 is a cross-sectional view taken along an axis to show a schematic configuration of a sealing device according to a third embodiment of the present invention. FIG. [Figure 11] 11 is a cross-sectional view of a cross section taken along the axis of a conductive elastic body portion of the sealing device shown in FIG. 10. [Figure 12] 11 is a partial cross-sectional view of the sealing device shown in FIG. 10, which is disposed in an annular space between an inner peripheral side member and an outer peripheral side member which rotate relatively to each other. [Figure 13] FIG. 11 is a partial perspective view of a sealing device according to a fourth embodiment of the present invention. [Figure 14] FIG. 13 is a partial perspective view of a sealing device according to a fifth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] FIG. 1 is a partial cross-sectional view of a sealing device 1 according to a first embodiment of the present invention, which is disposed in an annular space between an inner peripheral member and an outer peripheral member which rotate relatively to each other, and FIG. 2 is a partial perspective view of the sealing device 1 shown in FIG. 1. Note that FIG. 1 shows one side of a cross section (hereinafter, simply referred to as a cross section) of the sealing device 1 along the axis x, and FIG. 2 shows a state in which a part of the sealing device 1 is cut along a plane along the axis x. The sealing device 1 according to this embodiment is intended to seal an annular space between an inner peripheral member and an outer peripheral member which rotate relatively to each other in, for example, an electric vehicle (EV) such as a battery electric vehicle (BEV), a hybrid vehicle (HV), or a fuel cell vehicle (FCV). The inner peripheral member and the outer peripheral member are, for example, members of a drive device equipped with an electric motor, the inner peripheral member is, for example, a rotating shaft of the electric motor, and the outer peripheral member is, for example, a housing of the drive device through which the rotating shaft of the electric motor passes. In this embodiment, as shown in Fig. 1, the sealing device 1 is intended to seal an annular space 104 between a shaft 101, which is a rotating shaft of an electric motor (not shown) of a drive device (not shown), and a housing 102 of the drive device. Note that application of the sealing device 1 is not limited to such drive devices.

[0017] As shown in Figs. 1 and 2, the sealing device 1 includes a conductive elastic body part 2 that is an annular member around an axis x and has a portion formed from a conductive elastic material. The conductive elastic body part 2 is capable of contacting a shaft 101 and a housing 102 of an electric motor. The conductive elastic body part 2 is also capable of forming a conductive circuit 3 between the shaft 101 and the housing 102 of the electric motor. The impedance of the conductive circuit 3 during rotation of the shaft 101 of the electric motor at a peripheral speed of 60 m / s or less is 0.01 Ω or more and 100 Ω or less. The configuration of the sealing device 1 will be specifically described below.

[0018] The conductive elastic body part 2 is designed to maintain electrical contact with the shaft 101 even when it receives a force that breaks the contact between the conductive elastic body part 2 and the shaft 101 based on the rotation of the shaft 101 of the electric motor. When the rotating shaft to which the conductive lip is applied rotates at high speed, the conductive lip made of a conventional elastic material having a conductive radial type receives a force from the rotating shaft rotating at high speed that acts to break the contact between the conductive lip and the rotating shaft. When the rotating shaft rotates at a high speed such as a peripheral speed of 30 m / s or more, it is considered that the contact area of ​​the conventional radial type conductive lip with the rotating shaft may become small due to the force that breaks the contact. For this reason, when the rotating shaft rotates at a high speed such as a peripheral speed of 30 m / s or more, it is considered that the conductivity between the conductive lip and the rotating shaft may decrease in the conventional radial type conductive lip. The peripheral speed of the rotating shaft is the distance that the outer circumferential surface of the rotating shaft moves per unit time. More specifically, the peripheral speed of the rotating shaft is the distance that one point on the outer circumferential surface of the rotating shaft moves per unit time.

[0019] In contrast, the sealing device 1 maintains electrical contact between the conductive elastic body part 2 and the shaft 101 even when the shaft 101 rotates at high speed by using a lubricant such as conductive grease, and the impedance of the conductive circuit 3 formed by the conductive elastic body part 2 is set to 0.01 Ω or more and 100 Ω or less even when the electric motor shaft 101 rotates at a peripheral speed of 60 m / s or less. In this way, the sealing device 1 can keep the impedance in the range of 0.01 Ω or more and 100 Ω or less, even when the electric motor shaft 101 rotates at high speed, and is able to suppress a decrease in conductivity.

[0020] As shown in Figs. 1 and 2, the sealing device 1 has an annular shape around an axis x, and is attached to an annular space 104 between a through hole 103 provided in a housing 102 and a shaft 101 of an electric motor that passes through the through hole 103 and exits from the housing 102, thereby sealing the space 104. In this way, the sealing device 1 prevents a sealed object such as lubricating oil in the housing 102 from leaking to the atmosphere. In the illustrated example, as shown in Fig. 1, the side indicated by the symbol I is the sealed object side, and the side indicated by the symbol O is the atmosphere side. Also, as shown in Fig. 1, the axis x of the sealing device 1 attached to the space 104 coincides or approximately coincides with the axis of the shaft 101. In the illustrated example, the axis x of the sealing device 1 coincides with the axis of the shaft 101.

[0021] The sealing device 1 has a reinforcing ring 10, which is a metal member annular around an axis x, and a seal body 20 as a conductive elastic body portion 2, which is a member attached to the reinforcing ring 10. As shown in Figs. 1 and 2, for example, the reinforcing ring 10 has a cylindrical portion 11 that is a cylindrical portion extending along the axis x, a bent portion 12 that is a ring-shaped portion folded back from an end portion (end portion 11a) on the atmosphere side O of the reinforcing ring 11 to the sealed object side I, and an annular portion 13 that is a ring-shaped portion extending from an end portion (end portion 12a) on the inner periphery side of the bent portion 12 to the inner periphery side. The cylindrical portion 11, the bent portion 12, and the annular portion 13 are parts of the reinforcing ring 10 that are integrally formed from the same metal material. The reinforcing ring 10 is formed, for example, by pressing an annular metal plate. 1, the tubular portion 11 is a cylindrical or approximately cylindrical portion with the axis x as its central axis or approximately central axis, and is shaped to fix the sealing device 1 to the through hole 103 in a use state in which the sealing device 1 is attached to the through hole 103 of the housing 102. Note that the material of the reinforcing ring 10 is not limited to a metal material.

[0022] The seal body 20 is formed from a conductive elastic material, and this conductive elastic material is cross-linked and bonded to the reinforcing ring 10 to be integrally molded. The seal body 20 is, for example, a molded body obtained by insert molding using the reinforcing ring 10 as an insert part. The conductive elastic material forming the seal body 20 is, for example, conductive rubber. The conductive elastic material forming the seal body 20 is, for example, a material having heat resistance of -40° to 200°, for example, conductive fluororubber (FKM). As shown in, for example, Figs. 1 and 2, the seal body 20 is attached to the reinforcing ring 10 so as to cover the entire reinforcing ring 10, and has a seal portion 21, a base portion 22, a gasket portion 23, and a cover portion 24. The seal portion 21 has a conductive lip portion 30 and a seal lip portion 40. The seal portion 21, the base portion 22, the gasket portion 23, and the cover portion 24 are parts of the seal body 20 integrally formed from the same material.

[0023] The base portion 22 is a portion located at and near the end on the inner periphery side of the annular portion 13 of the reinforcing ring 10, the gasket portion 23 is a portion that covers the outer periphery surface 11b of the tubular portion 11 of the reinforcing ring 10, and the cover portion 24 is a portion that covers the reinforcing ring 10 between the base portion 22 and the gasket portion 23. The outer diameter of the gasket portion 23 is equal to or larger than the diameter of the inner periphery surface 103a of the through hole 103 of the housing 102. Therefore, when the sealing device 1 is attached to the space 104 of the housing 102, the gasket portion 23 is compressed in the radial direction between the tubular portion 11 of the reinforcing ring 10 and the housing 102, the sealing device 1 is fixed to the housing 102, and the gap between the inner periphery surface 103a of the through hole 103 of the housing 102 and the sealing device 1 is sealed.

[0024] As described above, as shown in Figs. 1 and 2, the seal portion 21 is a bifurcated portion from the base portion 22, and has the conductive lip portion 30 and the seal lip portion 40 extending back to back along the axis x. The conductive lip portion 30 extends from the end of the atmosphere side O of the base portion 22 toward the atmosphere side O so as to be able to come into contact with the outer circumferential surface 101a of the shaft 101. The seal lip portion 40 extends from the end of the sealed object side I of the base portion 22 toward the sealed object side I so as to be able to come into contact with the outer circumferential surface 101a of the shaft 101. The conductive lip portion 30 extends, for example, parallel or approximately parallel to the axis x, and the seal lip portion 40 extends, for example, parallel or approximately parallel to the axis x.

[0025] 1 and 2, the seal lip portion 40 has a seal lip 41 at the end on the sealed object side I. The seal lip 41 is a portion extending along a circular ring or an approximately circular ring centered or approximately centered on the axis x, and has a cross-sectional shape of a wedge convex toward the inner periphery. The seal lip portion 40 has a shape such that the seal lip 41 comes into contact with the outer periphery 101a of the shaft 101.

[0026] Specifically, for example, the seal lip 41 has a sealed object side surface 42 and an atmosphere side surface 43 which form the above-mentioned wedge-shaped cross section, as shown in Fig. 2. The sealed object side surface 42 is an annular surface facing the inner periphery side and the sealed object side I, and the atmosphere side surface 43 is an annular surface facing the inner periphery side and the atmosphere side O. As shown in Figs. 1 and 2, the sealed object side surface 42 and the atmosphere side surface 43 intersect with each other on the inner periphery side, forming a tip 44 which describes a circle or a nearly circle at the intersection.

[0027] The air side surface 43 is provided with a plurality of screw grooves 45 as fluid return sections. These screw grooves 45 are grooves recessed from the air side surface 43 and inclined in the rotation direction of the shaft 101 starting from the tip 44. The screw grooves 45 generate an airflow from the air side surface 43 toward the sealed object side surface 42 as the shaft 101 rotates, and generate a screw pump action that returns the sealed object (not shown) that has leaked beyond the tip 44 to the air side O to the sealed object side I. Note that the air side surface 43 may have a screw protrusion 46 shown in FIG. 5 instead of the screw groove 45. The screw protrusion 46 is a protrusion protruding from the air side surface 43 and inclined in the rotation direction of the shaft 101 starting from the tip 44.

[0028] 1 and 2, the seal lip portion 40 is formed so that the seal lip 41 contacts the outer peripheral surface 101a of the shaft 101 with a predetermined interference at the tip 44 and its vicinity. In addition, the seal lip portion 40 is provided with a garter spring 47 at a position facing away from the seal lip 41. The garter spring 47 applies a tension force to the seal lip portion 40 that presses the seal lip 41 inward, thereby increasing the tension force that presses the seal lip 41 against the outer peripheral surface 101a of the shaft 101.

[0029] 1 and 2, the conductive lip 30 has a conductive lip 31 at the end on the atmosphere side O. The conductive lip 31 is a portion extending along a circular ring or an approximately circular ring centered or approximately centered on the axis x, and has a cross-sectional shape of, for example, a rectangular or trapezoidal shape convex toward the inner periphery. The conductive lip 30 has a shape such that the conductive lip 31 comes into contact with the outer periphery 101a of the shaft 101.

[0030] Specifically, for example, the conductive lip 31 has an annular contact surface 32 that forms the above-mentioned rectangular or trapezoidal cross section, as shown in Figs. 1 and 2. The contact surface 32 is adapted to be in surface contact with the outer circumferential surface 101a of the shaft 101, and is, for example, a cylindrical surface or an approximately cylindrical surface with the axis x as the central axis or approximately central axis. The contact surface 32 is not limited to a cylindrical surface or an approximately cylindrical surface, and may be a surface of another shape. The contact surface 32 may be, for example, an annular surface that draws a curved line that is convex toward the inner circumferential side in the cross section. In this case, the contact surface 32 deforms along the outer circumferential surface 101a of the shaft 101 in the usage state, so that the contact area with the outer circumferential surface 101a of the shaft 101 can be expanded or maintained.

[0031] FIG. 3 is a diagram showing a part of the contact surface 32 of the conductive lip 31 as seen from the inner circumferential side, FIG. 4(A) is a cross-sectional view along the line AA in FIG. 3, and FIG. 4(B) is a cross-sectional view along the line BB in FIG. 3. As shown in FIGS. 2, 3, 4(A), and 4(B), the contact surface 32 is provided with a plurality of annular grease grooves 33 around the axis x. As shown in FIGS. 4(A) and (B), the grease grooves 33 are grooves recessed from the contact surface 32 to the outer circumferential side, and are, for example, annular grooves extending along a circular ring or a substantially circular ring with the axis x as the central axis or substantially central axis. In addition, the grease grooves 33 are provided, for example, at equal or substantially equal intervals in the direction of the axis x. In the illustrated example, three grease grooves 33 are provided, but the number of grease grooves 33 is not limited to three, and may be one, two, or four or more.

[0032] As shown in Figs. 3, 4(A) and 4(B), grease G is accommodated and held in the grease groove 33 as a lubricant. The grease G held in the grease groove 33 is conductive grease. The shape of the grease groove 33 is preferably a shape suitable for holding the grease G. For example, the depth of the grease groove 33 is preferably a depth capable of holding the grease G. The cross-sectional shape of the grease groove 33 is, for example, a parabolic shape as shown in Figs. 4(A) and (B). Note that the cross-sectional shape of the grease groove 33 is not limited to this parabolic shape, and may be another shape such as a rectangular shape or a curved shape.

[0033] 2, 3, and 4(B), a plurality of communication grooves 34 are provided on the contact surface 32 of the conductive lip 31. The communication grooves 34 are grooves that extend along the axis x over the entire width of the contact surface 32 in the axis x direction, that are recessed from the contact surface 32 toward the outer periphery, and that intersect and communicate with the grease grooves 33 to communicate the space S (see FIG. 1) generated between the shaft 101, the conductive lip portion 30, and the seal lip portion 40 with the space on the atmosphere side O. The communication grooves 34 extend, for example, parallel or approximately parallel to the axis x, and are provided at equal or approximately equal angular intervals around the axis x.

[0034] For example, the grease G is filled only in the grease groove 33, and is not filled in the communication groove 34. As a result, the grease G remains in the grease groove 33 and is less likely to enter the communication groove 34. Although the grease G may be carried to the communication groove 34 by the rotation of the shaft 101, it is possible to prevent the grease G from clogging the communication groove 34 by forming the communication groove 34 to be somewhat wider or deeper in the circumferential direction. For this reason, for example, the groove width and depth of the communication groove 34 are set to values ​​that prevent the grease G from clogging the communication groove 34. The groove width of the communication groove 34 is the width of the communication groove 34 in the circumferential direction, which is the direction around the axis x.

[0035] As described later, the communication groove 34 acts to prevent the space S (see FIG. 1) generated between the shaft 101, the conductive lip portion 30, and the seal lip portion 40 from becoming negative pressure. The form of the communication groove 34, such as the shape, size, number, etc. of the communication groove 34, may be various forms as long as it has the effect of preventing the space S from becoming negative pressure.

[0036] 1, 2, 4(A), and 4(B), the conductive lip portion 30 is provided with a garter spring 35 at a position facing away from the conductive lip 31. The garter spring 35 applies a tension force to the conductive lip portion 30 that presses the conductive lip 31 inward, thereby increasing the tension force that presses the conductive lip 31 against the outer circumferential surface 101a of the shaft 101.

[0037] As described above, the contact surface 32 of the conductive lip 31 is in surface contact with the outer circumferential surface 101a of the shaft 101. As a result, as described below, the grease G held in the grease groove 33 is filled between the contact surface 32 and the outer circumferential surface 101a of the shaft 101 when the contact surface 32 contacts the outer circumferential surface 101a of the shaft 101. For this reason, it is preferable that the width (axial length) of the contact surface 32 of the conductive lip 31 in the direction of the axis x is set to a value such that the spread (area) and filling rate of the grease G filled between the contact surface 32 and the outer circumferential surface 101a of the shaft 101 provide favorable conductivity between the conductive lip 31 and the shaft 101, which will be described below.

[0038] For example, the axial length of the contact surface 32 is set based on the groove width, number, or shape of the grease grooves 33 arranged in the direction of the axis x. As shown in Figures 1, 2, 4(A), and 4(B), in the illustrated example, the axial length of the contact surface 32 of the conductive lip 31 is equal to or longer than the diameter of the garter spring 35. The axial length of the contact surface 32 may be the same as the diameter of the garter spring 35, or may be shorter than the diameter of the garter spring 35, as long as the grease grooves 33 can be provided.

[0039] The sealing device 1 uses grease G as an essential element when in use. For this reason, for example, the grease groove 33 holds the grease G in advance so that the grease G can be filled between the contact surface 32 and the outer circumferential surface 101a of the shaft 101. Therefore, the sealing device 1 holds the grease G in advance in the grease groove 33 provided in the contact surface 32, and constitutes a grease supplying section 36 that fills the gap between the contact surface 32 and the outer circumferential surface 101a of the shaft 101 with the grease G.

[0040] The seal body 20 of the sealing device 1 is an integral structure molded from conductive rubber, and covers the reinforcing ring 10. In addition, a film of grease G is interposed between the contact surface 32 of the conductive lip 31 and the outer circumferential surface 101a of the shaft 101, and the grease G has electrical conductivity. Therefore, in the sealing device 1, a conductive circuit 3 (see FIG. 1 ) is formed that passes through the seal body 20 including the grease G and the reinforcing ring 10, from the conductive lip 31 and the seal lip 41 that contact the shaft 101 via the grease G, through the gasket portion 23, and reaches the housing 102. In other words, the conductive conductive circuit 3 formed by the conductive elastic body portion 2 (seal body 20) of the sealing device 1 is formed by the grease G and the seal body 20, and in addition, by the grease G, the reinforcing ring 10, and the seal body 20.

[0041] Next, the operation of the sealing device 1 having the above-mentioned configuration will be described. In the sealing device 1 in use, which is attached between the through hole 103 of the housing 102 of the drive device and the shaft 102, the conductive lip 31 and the seal lip 41 contact the outer circumferential surface 101a of the shaft 101 to seal the object to be sealed to the object to be sealed side I, and prevent the object to be sealed from leaking from the object to be sealed side I. In this sealing, the seal lip 41 performs a primary sealing function of preventing the object to be sealed from leaking from the object to be sealed side I. The conductive lip 31 performs a secondary sealing function of blocking the object to be sealed by sealing between the contact surface 32 and the outer circumferential surface 101a of the shaft 101 when the object to be sealed leaks from the seal lip 41. The conductive lip 31 also functions as a dust lip to prevent the ingress of foreign matter such as rainwater, muddy water, and dust from the atmosphere side O to the object to be sealed side I.

[0042] In a vehicle equipped with an electric motor, such as an electric vehicle (EV), electromagnetic noise may be generated by induced current generated by the motor. Electromagnetic noise may also be generated by the on / off operation of an inverter for controlling the current supplied to an electric motor, such as an electric motor, or by induced voltage of the electric motor itself. The electromagnetic noise may be transmitted to, for example, the shaft 101, and radiated using the shaft 101 as an antenna. The electromagnetic noise thus radiated may cause communication failure in an in-vehicle radio or an in-vehicle wireless device, and may also cause various electronic devices to malfunction. Such electromagnetic noise may also cause electrolytic corrosion in metal parts.

[0043] In the sealing device 1, the seal body 20 made by molding conductive rubber constitutes the conductive circuit 3, and electromagnetic noise transmitted to the shaft 101 is passed to the housing 102. This makes it possible to prevent communication failures and malfunctions in electronic devices, and electrolytic corrosion in metal parts.

[0044] As described above, the grease G is filled between the contact surface 32 of the conductive lip 31 and the shaft 101, and a coating of the grease G is interposed between the contact surface 32 and the shaft 101, and this coating of the grease G constitutes a part of the conductive circuit 3. Therefore, it is possible to reduce or eliminate the gap between the contact surface 32 of the conductive lip 31 and the shaft 101, and it is possible to increase the conductivity between the contact surface 32 of the conductive lip 31 and the shaft 101. As a result, the conductive circuit 3 can increase the flow rate of the electromagnetic noise transmitted to the shaft 101 to the housing 102, and it is possible to further reduce the occurrence of malfunctions due to the electromagnetic noise.

[0045] In addition, when the shaft 101 rotates at high speed, the conductive lip portion 30 receives a force that breaks the contact between the conductive lip 31 and the shaft 101 due to the rotation of the shaft 101. Therefore, when the shaft 101 rotates at high speed, for example, when the shaft 101 rotates at a peripheral speed of 30 m / s or more, the contact surface 32 of the conductive lip 31 may separate from the outer circumferential surface 101a of the shaft 101, causing a gap. In contrast, in the sealing device 1, grease G is filled between the contact surface 32 of the conductive lip 31 and the outer circumferential surface 101a of the shaft 101, and a coating of grease G is interposed between the contact surface 32 and the outer circumferential surface 101a of the shaft 101. Therefore, even if a gap that cuts off electrical conduction occurs between the contact surface 32 of the conductive lip 31 and the outer circumferential surface 101a of the shaft 101 during high speed rotation of the shaft 101, the gap is filled with the grease G. Therefore, even when the shaft 101 rotates at high speed, the conductive performance between the contact surface 32 of the conductive lip 31 and the shaft 101 is maintained, and the flow rate of electromagnetic noise transmitted to the shaft 101 to the housing 102 can be maintained.

[0046] 6, in the sealing device 1, the impedance of the conductive circuit 3 can be set to 0.01 Ω or more and 100 Ω or less when the electric motor shaft 101 rotates at a peripheral speed of 60 m / s or less. As a result, even when the electric motor shaft 101 rotates at high speed, the sealing device 1 can keep the impedance of the conductive circuit 3 in the range of 0.01 Ω or more and 100 Ω or less, and can suppress a decrease in conductivity.

[0047] The impedance of the conductive circuit 3 of the sealing device 1 can be measured by, for example, an impedance measuring device 200 as shown in FIG. 7. The impedance measuring device 200 has an impedance analyzer 201. In the impedance measuring device 200, one terminal of the impedance analyzer 201 is in contact with the shaft 101 via a conductive member 202 such as a copper plate, and the other terminal of the impedance analyzer 201 is fixed to the housing 102 via a conductive member 203. The shaft 101 is slidable relative to the conductive member 202. In the impedance measuring device 200, the shaft 101 may be replaced by a member that imitates the shape of the shaft 101, and similarly, the housing 102 may be replaced by a member that imitates the shape of the housing 102.

[0048] Measurement of the impedance of the conductive circuit 3 of the sealing device 1 using the impedance measuring device 200 is performed by rotating the shaft 101 at a rotation speed between a circumferential speed of 0 to 60 m / s and detecting the impedance of the conductive circuit 3 at this rotation speed by the impedance analyzer 201. This allows the impedance of the conductive circuit 3 at a rotation speed of the shaft 101 of a circumferential speed of 0 to 60 m / s to be obtained. As described above, the measured value of the impedance of the conductive circuit 3 at a rotation speed of the shaft 101 of a circumferential speed of 0 to 60 m / s is 0.01 Ω to 100 Ω, as shown in FIG. 6.

[0049] The conditions for measuring the impedance of the conductive circuit 3 by the impedance measuring device 200 are, for example, a measurement frequency of the impedance analyzer 201 of 500 kHz and a voltage amplitude of 5V.

[0050] In addition, the tip 44 of the seal lip 41 and its vicinity are lubricated by the sealed object, such as lubricating oil, present on the sealed object side I. In contrast, the contact surface 32 of the conductive lip 31 cannot be expected to be lubricated by the sealed object on the sealed object side I. Therefore, the conductive lip 31 of the sealing device 1 is provided with a grease groove 33 on the contact surface 32 to hold grease G, and when the shaft 101 rotates, the grease G in the grease groove 33 is filled between the contact surface 32 and the shaft 101. This allows the contact surface 32 to be lubricated by the grease G, and the contact surface 32 and the shaft 101 to be protected from wear and damage.

[0051] In addition, when the shaft 101 rotates, the screw groove 45 or the screw projection 46 provided on the seal lip 41 returns the sealed object that has seeped out from the sealed object side I beyond the tip 44 to the atmosphere side O to the sealed object side I by the screw pump action. On the other hand, the screw pump action tries to create a negative pressure in the space S between the shaft 101, the conductive lip portion 30, and the seal lip portion 40. If it is assumed that the space S becomes negative pressure, the conductive lip 31 and the seal lip 41 are pressed more strongly against the shaft 101. At this time, abnormal friction may occur particularly at the tip 44 of the seal lip 41 and its vicinity, which, unlike the conductive lip 31, does not have a coating of grease G formed between the seal lip 41 and the shaft 101.

[0052] In the sealing device 1, when a screw pump action occurs due to the screw groove 45 or the screw protrusion 46, air on the atmosphere side O is introduced into the space S through the communication groove 34 provided in the contact surface 32 of the conductive lip 31. This prevents the space S from becoming negative pressure or prevents the negative pressure in the space S from increasing, thereby preventing abnormal friction of the seal lip 41 that would occur if the space S became negative pressure.

[0053] Next, a sealing device 4 according to a second embodiment of the present invention will be described. FIG. 8 is a partial cross-sectional view of the sealing device 4 according to the second embodiment of the present invention arranged in an annular space between an inner peripheral side member and an outer peripheral side member which rotate relatively to each other, and FIG. 9 is a partial perspective view of the sealing device 4 shown in FIG. 8. In this embodiment, the sealing device 4, like the sealing device 1, seals an annular space 104 between a shaft 101 which is a rotating shaft of an electric motor (not shown) of a drive device (not shown) and a housing 102 of the drive device, as shown in FIG. 8. Note that the application of the sealing device 4 is not limited to such a drive device. Hereinafter, regarding the sealing device 4, the same reference numerals as those of the sealing device 1 will be used for the same configuration or configuration having the same function as the above-mentioned sealing device 1, and the description thereof will be omitted.

[0054] 8 and 9, the sealing device 4 has a reinforcing ring 15 having a different shape from the reinforcing ring 10 of the sealing device 1, and the cross-sectional shape of the reinforcing ring 15 is L-shaped. Specifically, the reinforcing ring 15 has, for example, a cylindrical portion 11 and an annular portion 16 that is a circular portion extending from an end portion 11c of the cylindrical portion 11 on the sealed object side I to the inner circumferential side.

[0055] In addition, in accordance with the shape of the reinforcing ring 15, the sealing device 4 has a seal body 25 having a shape different from that of the seal body 20 of the sealing device 1. Specifically, for example, as shown in Figs. 8 and 9, in the seal body 25 of the sealing device 4, the seal portion 21 does not have a seal lip portion 40 extending from the base portion 22 to the sealed object side I, unlike the seal portion 21 of the sealing device 1. In the seal lip portion 40 of the sealing device 4, the seal lip 48 is formed at the end portion on the inner circumferential side of the base portion 22. In addition, the seal lip portion 40 of the sealing device 4 does not have a garter spring 47.

[0056] The seal lip 48 of the sealing device 4 has a planar seal surface 49 formed to be able to come into contact with the shaft 101, similar to the conductive lip 31. The seal surface 49 is a cylindrical surface or a substantially cylindrical surface with the axis x as a central axis or a substantially central axis, as shown in FIG. 9, for example. The seal lip 48 does not have a grease groove 33 or a communication groove 34, unlike the contact surface 32 of the conductive lip 31. The seal lip 48 does not have a screw groove 45 or a screw protrusion 46, unlike the seal lip 41 of the sealing device 1. That is, the seal lip 48 does not have a fluid return portion that exerts a screw pump action. For this reason, in the sealing device 4, the space S generated between the conductive lip portion 30 and the seal lip 48 does not become negative pressure, so the contact surface 32 of the conductive lip 31 does not have a communication groove 34. The contact surface 32 of the conductive lip 31 of the sealing device 4 may have a communication groove 34.

[0057] The sealing device 4 having the above-mentioned configuration functions in the same manner as the sealing device 1 in terms of electromagnetic noise countermeasures and lubrication functions. That is, the seal portion 21 of the sealing device 4 prevents leakage of the sealed object from the sealed object side I by contacting the conductive lip 31 and the seal lip 48 with the shaft 101. At this time, the seal lip 48 performs a primary sealing function of preventing leakage of fluid from the sealed object side I by the seal surface 49. The conductive lip 31 performs a secondary sealing function of blocking the fluid leaking from the seal lip 48 by the contact surface 32. The conductive lip 31 also functions as a dust lip that prevents foreign matter from entering from the atmosphere side O to the sealed object side I.

[0058] Also in the sealing device 4, similarly to the sealing device 1, the conductive conductive circuit 3 formed by the conductive elastic body portion 2 (seal body 25) is composed of the grease G and the seal body 25, and in addition, the grease G, the reinforcing ring 15, and the seal body 25, and electromagnetic noise transmitted to the shaft 101 is guided to the housing 102. This makes it possible to prevent communication failure or malfunction in electronic devices and electrolytic corrosion in metal parts.

[0059] In the sealing device 4, as in the sealing device 1, grease G is filled between the contact surface 32 of the conductive lip 31 and the shaft 101, and a coating of grease G is interposed between the contact surface 32 and the shaft 101. This makes it possible to reduce or eliminate a gap that blocks electrical conduction between the contact surface 32 of the conductive lip 31 and the shaft 101, and to increase the conductivity between the contact surface 32 of the conductive lip 31 and the shaft 101. This allows the conductive circuit 3 to increase the flow rate of the electromagnetic noise transmitted to the shaft 101 to the housing 102, and further reduces the occurrence of malfunctions due to electromagnetic noise.

[0060] Also in the sealing device 4, grease G is filled between the contact surface 32 of the conductive lip 31 and the outer circumferential surface 101a of the shaft 101, and a coating of grease G is interposed between the contact surface 32 and the outer circumferential surface 101a of the shaft 101. Therefore, even if a gap occurs between the contact surface 32 of the conductive lip 31 and the outer circumferential surface 101a of the shaft 101 when the shaft 101 rotates at high speed, this gap is filled with grease G. Therefore, even when the shaft 101 rotates at high speed, the conductive performance between the contact surface 32 of the conductive lip 31 and the shaft 101 is maintained, and the flow rate of the electromagnetic noise transmitted to the shaft 101 to the housing 102 can be maintained.

[0061] Therefore, in the sealing device 4, the impedance of the conductive circuit 3 can be set to 0.01 Ω or more and 100 Ω or less when the electric motor shaft 101 rotates at a peripheral speed of 60 m / s or less, as shown in Fig. 6. As a result, even when the electric motor shaft 101 rotates at high speed, the sealing device 4 can keep the impedance of the conductive circuit 3 in the range of 0.01 Ω or more and 100 Ω or less, and can suppress a decrease in conductivity.

[0062] Next, a sealing device 5 according to a third embodiment of the present invention will be described. FIG. 10 is a cross-sectional view taken along the axis x to show a schematic configuration of the sealing device 5 according to the third embodiment of the present invention, and FIG. 11 is a cross-sectional view taken along the axis x of the conductive elastic body portion 6 of the sealing device 5. FIG. 12 is a partial cross-sectional view of the sealing device 5 disposed in an annular space between an inner peripheral side member and an outer peripheral side member which rotate relatively to each other. In this embodiment, the sealing device 5, like the sealing device 1, is intended to seal an annular space 104 between a shaft 101, which is a rotating shaft of an electric motor (not shown) of a drive device (not shown), and a housing 102 of the drive device, as shown in FIG. 12. Note that the application of the sealing device 5 is not limited to such a drive device.

[0063] 10, 11, and 12, the side in the direction of the arrow a in the direction of the axis x (one side in the axial direction) is the atmosphere side O (outside), and the side in the direction of the arrow b in the direction of the axis x (the other side in the axial direction) is the sealed fluid side I (inside). In addition, in the direction perpendicular to the axis x (radial direction), the side in the direction away from the axis x (direction of the arrow c) is the outer circumferential side, and the side in the direction approaching the axis x (direction of the arrow d) is the inner circumferential side.

[0064] As shown in Figs. 10 to 12, the sealing device 5 includes a conductive elastic body part 6 which is an annular member around an axis x and is made of a conductive elastic material. The conductive elastic body part 6 is capable of coming into contact with a shaft 101 and a housing 102 of the electric motor. The conductive elastic body part 6 is also capable of forming a conductive circuit 8 between the shaft 101 and the housing 102 of the electric motor. The impedance of the conductive circuit 8 during rotation of the shaft 101 of the electric motor at a peripheral speed of 60 m / s or less is 0.01 Ω or more and 100 Ω or less. The configuration of the sealing device 5 will be specifically described below.

[0065] The conductive elastic body 6 is designed to maintain electrical contact with the shaft 101 even when it receives a force that breaks the contact between the conductive elastic body 6 and the shaft 101 due to the rotation of the shaft 101 of the electric motor. As described above, when the rotating shaft to which the conductive lip is applied rotates at high speed, the conductive lip made of a conventional elastic material having a conductive radial type receives a force from the rotating shaft that rotates at high speed to break the contact between the conductive lip and the rotating shaft. When the rotating shaft rotates at a high speed, such as a peripheral speed of 30 m / s or more, it is considered that the contact area of ​​the conventional radial type conductive lip with the rotating shaft may become smaller due to the force that breaks the contact. For this reason, it is considered that when the rotating shaft rotates at a high speed, such as a peripheral speed of 30 m / s or more, the conductivity between the conductive lip and the rotating shaft may decrease in the conventional radial type conductive lip.

[0066] In contrast, the conductive elastic part 6 of the sealing device 5 maintains electrical contact between the conductive elastic part 6 and the shaft 101 even when the shaft 101 rotates at high speed, and the impedance of the conductive circuit 8 formed by the conductive elastic part 6 is set to be 0.01 Ω or more and 100 Ω or less even when the shaft 101 of the electric motor rotates at a peripheral speed of 60 m / s or less. In this way, the sealing device 5 can keep the impedance in the range of 0.01 Ω or more and 100 Ω or less even when the shaft 101 of the electric motor rotates at high speed, and is able to suppress a decrease in conductivity.

[0067] As shown in FIG. 10, the sealing device 5 includes a sealing device main body 7. The sealing device main body 7 includes a reinforcing ring 50 and a seal main body 60 that is a member formed of a rubber-like elastic body attached to the reinforcing ring 50. The reinforcing ring 50 includes a cylindrical portion 51 that is a cylindrical portion extending along the axis x, a bent portion 52 that is a ring-shaped portion folded back from an end portion (end portion 51a) of the cylindrical portion 51 on the atmosphere side O to the atmosphere side O, and an annular portion 53 that is a ring-shaped portion extending from an end portion (end portion 52a) on the inner periphery side of the bent portion 52 to the inner periphery side. The cylindrical portion 51, the bent portion 52, and the annular portion 53 are portions of the reinforcing ring 50 that are integrally formed from the same metal material. The reinforcing ring 50 is formed, for example, by pressing an annular metal plate. 10 and 12, for example, the tubular portion 51 has a cylindrical or approximately cylindrical portion with the axis x as its central axis or approximately central axis, and is shaped to fix the sealing device 5 to the through hole 103 in a use state in which the sealing device 5 is attached to the through hole 103 of the housing 102. The material of the reinforcing ring 50 is not limited to a metal material.

[0068] The seal body 60 is formed from an elastic material having a lower electrical conductivity than the elastic material having electrical conductivity, specifically, an elastic material having no electrical conductivity, and this elastic material is bonded to the reinforcing ring 50 by cross-linking and integrally molded. The seal body 60 is, for example, a molded body obtained by insert molding using the reinforcing ring 50 as an insert part. As shown in FIG. 10, for example, the seal body 60 is attached to the reinforcing ring 50 so as to cover the entire reinforcing ring 50, and has a seal portion 61, a base portion 62, a gasket portion 63, and a cover portion 64. The seal portion 61 also has a seal lip portion 65 and a dust lip portion 66. The seal portion 61, the base portion 62, the gasket portion 63, and the cover portion 64 are parts of the seal body 60 integrally formed from the same material.

[0069] The base portion 62 is a portion located at and near the end on the inner periphery side of the annular portion 53 of the reinforcing ring 50, the gasket portion 63 is a portion that covers the outer periphery surface 51b of the tubular portion 51 of the reinforcing ring 50, and the cover portion 64 is a portion that covers the reinforcing ring 50 between the base portion 62 and the gasket portion 63. The gasket portion 63 has a portion (contact portion 63a) whose outer diameter is the same as or larger than the inner diameter of the inner periphery surface 103a of the through hole 103 of the housing 102. Therefore, when the sealing device 5 is attached to the space 104 of the housing 102, the contact portion 63a of the gasket portion 63 is compressed in the radial direction between the tubular portion 51 of the reinforcing ring 50 and the housing 102, so that the sealing device 5 is fixed to the housing 102, and the gap between the inner periphery surface 103a of the through hole 103 of the housing 102 and the sealing device 5 is sealed.

[0070] In the seal portion 61, the seal lip portion 65 and the dust lip portion 66 extend back to back from each other along the axis x from the base portion 62 as shown in Figs. 10 and 12. The seal lip portion 65 extends from the end of the base portion 62 on the sealed object side I toward the sealed object side I so as to be able to contact, for example, the outer circumferential surface 101a of the shaft 101. The dust lip portion 66 extends from the end of the atmosphere side O of the base portion 62 toward the atmosphere side O and the inner circumferential side so as to be able to contact, for example, the outer circumferential surface 101a of the shaft 101. The seal lip portion 65 is adapted to prevent leakage of the sealed object, and the dust lip portion 66 is adapted to prevent the ingress of foreign matter such as rainwater, muddy water, and dust from the atmosphere side O to the sealed object side I. In addition, a garter spring 67 is attached to the seal lip portion 65 to increase the tension force that presses the seal lip portion 65 against the outer circumferential surface 101a of the shaft 101.

[0071] As shown in Figs. 10 and 11, the conductive elastic body 6 has a reinforcing ring 70 and a main body 80 which is a member attached to the reinforcing ring 70. The main body 80 is a member formed from a rubber-like conductive elastic material. The conductive elastic material of the main body 80 is, for example, conductive rubber. The conductive elastic material forming the main body 80 is, for example, a material having heat resistance of -40° or more and 200° or less, for example, conductive fluororubber (FKM). The main body 80 is integrally molded by cross-linking and bonding this conductive elastic material to the reinforcing ring 70. The main body 80 is, for example, a molded body obtained by insert molding using the reinforcing ring 70 as an insert part.

[0072] As shown in Figs. 10 and 11, the reinforcing ring 70 has a cylindrical portion 71 that is a cylindrical portion extending along the axis x, and an annular portion 72 that is an annular portion extending from an end (end 71a) of the cylindrical portion 71 on the atmosphere side O to the inner periphery side. The cylindrical portion 71 and the annular portion 72 are parts of the reinforcing ring 70 that are integrally formed from the same metal material. The reinforcing ring 70 is formed, for example, by pressing an annular metal plate. As shown in Figs. 10 and 11, the cylindrical portion 71 has a cylindrical or approximately cylindrical portion with the axis x as its central axis or approximately central axis, and is shaped to fix the conductive elastic body portion 6 between the sealing device main body portion 7 and the through hole 103 in a usage state in which the sealing device 5 is attached to the through hole 103 of the housing 102. The material of the reinforcing ring 70 is not limited to a metal material.

[0073] Specifically, as shown in Figs. 10 and 12, the cylindrical portion 71 is located on the outer circumferential side of the cylindrical portion 51 of the reinforcing ring 50 of the sealing device main body 7 in the sealing device 5, and has a shape such that the gasket portion 63 of the seal main body 60 is sandwiched and compressed between the cylindrical portion 51 of the reinforcing ring 50 and the cylindrical portion 71. The annular portion 72 has a shape such that the annular portion 72 comes into contact with the cover portion 64 on the atmosphere side O of the seal main body 60 of the sealing device main body 7 from the atmosphere side O in a state in which the conductive elastomer portion 6 is assembled to the sealing device main body 7 (assembled state) as shown in Figs. 10 and 12. In addition, the annular portion 72 extends more inward than the annular portion 53 of the reinforcing ring 50 of the sealing device main body 7, for example, as shown in Figs. 10 and 12.

[0074] Moreover, the reinforcing ring 70 has a sealing device joint 73 formed so as to be able to join the conductive elastic body portion 6 to the sealing device main body portion 7 in the portion on the atmosphere side O of the sealing device 5. The sealing device joint 73 has, for example, a cylindrical portion joint portion 74 and an annular portion joint portion 75.

[0075] The cylindrical joint portion 74 is formed so as to be joined to a part of the gasket portion 63 of the seal body 60 of the sealing device body 7. Specifically, for example, as shown in Figs. 10 and 12, in an assembled state in which the conductive elastic body portion 6 is assembled to the sealing device body 7, the cylindrical joint portion 74 has a shape such that the cylindrical joint portion 63b, which is a portion formed in a portion on the atmosphere side O from the contact portion 63a of the gasket portion 63, can be compressed between the cylindrical portion 51 of the reinforcing ring 50 and joined to the sealing device body 7. As shown in Figs. 10 and 12, for example, the cylindrical joint portion 63b protrudes outward from a portion (engaged portion 63c) between the contact portion 63a and the cylindrical joint portion 63b of the gasket portion 63, and does not protrude outward from the contact portion 63a.

[0076] Further, for example, the cylindrical portion joint portion 74 is formed with a cylindrical portion engaging portion 76 that engages with the gasket portion 63 at the engaged portion 63c of the gasket portion 63. In an assembled state, the cylindrical portion engaging portion 76 contacts or faces the engaged portion 63c of the gasket portion 63 from the outer circumferential side, and engages with the cylindrical portion joint portion 63b in the direction of the axis x.

[0077] The annular portion joint portion 75 is formed so as to be joinable to, for example, the part (atmosphere-side cover portion 64a) on the atmosphere side O of the cover portion 64 of the seal body 60 of the sealing device main body 7. Specifically, for example, as shown in Figs. 10 to 12, the annular portion joint portion 75 has a shape so as to be joinable to the annular portion jointed portion 68 formed on the atmosphere-side cover portion 64a. Specifically, for example, as shown in Figs. 10 to 12, the annular portion joint portion 75 is a portion that protrudes from the surface (surface 72a) of the annular portion 72 of the reinforcing ring 70 facing the sealed object side I to the sealed object side I, and the annular portion jointed portion 68 is a portion that is recessed to the sealed object side I formed on the atmosphere-side cover portion 64a so as to accommodate the annular portion joint portion 75 so as to be engageable with the annular portion joint portion 75, as shown in Figs. 10 and 12. The annular portion joining portion 75 is received in the annular portion to be joined 68 and engaged with the annular portion to be joined 68 .

[0078] 11, the main body 80 has a conductive lip 81, a base 82, and a connecting portion 83. The conductive lip 81, the base 82, and the connecting portion 83 are all parts of the main body 80 made of the same material. The base 82 is attached to the inner circumferential end (end 72b) of the annular portion 72 of the reinforcing ring 70 and its vicinity, and the conductive lip 81 extends from the base 82 toward the inner circumferential side.

[0079] As shown in Fig. 12, the conductive lip 81 is formed so as to come into contact with the outer circumferential surface 101a of the shaft 101 in the sealing device 5 attached between the through hole 103 of the housing 102 of the drive device and the shaft 102. The conductive lip 81 has a shape that increases rigidity against an external force toward the outer circumferential side in the radial direction. For example, as shown in Fig. 12, the conductive lip 81 is formed so as to be located radially between the end portion 72b or the base portion 82 of the annular portion 72 of the reinforcing ring 70 and the outer circumferential surface 101a of the shaft 101, and has a shape that increases rigidity against an external force toward the outer circumferential side in the radial direction. 10 and 11, in a free state not attached to a drive device, the conductive lip 81 extends from a base 82 toward the atmosphere side O (the side in the direction of arrow a) and the inner circumferential side (the side in the direction of arrow d), and a tip portion (tip portion 81a) of the conductive lip 81 extends so as to face the end portion 72b of the annular portion 72 of the reinforcing ring 70 or the base 82 in the radial direction. Note that the conductive lip 81 may have irregularities on the contact surface with the outer circumferential surface 101a of the shaft 101.

[0080] The connecting portion 83 is a portion formed in the sealing device 5 attached between the through hole 103 of the housing 102 of the drive device and the shaft 102 so that the conductive lip 81 is connected to the housing 102 via the base portion 82. As shown in FIG. 11, for example, the connecting portion 83 extends over a surface (surface 72c) facing the atmosphere side O of the annular portion 72 of the reinforcing ring 70 and a part of the atmosphere side O of a surface (surface 71b) facing the outer periphery side of the tubular portion 71 of the reinforcing ring 70. In addition, the connecting portion 83 is capable of contacting the inner circumferential surface 103a of the through hole 103 of the housing 102 at an end portion (end portion 83a) on the outer periphery side. As shown in FIG. 11, for example, the end portion 83a protrudes outward from the tubular portion 71 of the reinforcing ring 70, or protrudes outward to the same radial position as the tubular portion 71 of the reinforcing ring 70.

[0081] As described above, the main body 80 formed from a conductive elastic material has the conductive lip 81 in contact with the outer peripheral surface 101a of the shaft 101 and the end 83a of the connecting portion 83 in contact with the inner peripheral surface 103a of the through hole 103 in the housing 102, thereby forming a conductive circuit 8 by the conductive elastic body portion 6 between the shaft 101 and the housing 102.

[0082] Next, the operation of the sealing device 5 having the above-mentioned configuration will be described. In the sealing device 5 in use, which is attached between the through hole 103 of the housing 102 of the drive device and the shaft 102, the seal lip portion 65 contacts the outer circumferential surface 101a of the shaft 101, seals the sealed object to the sealed object side I, and prevents the sealed object from leaking from the sealed object side I. In addition, in the sealing device 5 in use, the dust lip portion 66 contacts the outer circumferential surface 101a of the shaft 101, and prevents foreign matter such as rainwater, muddy water, and dust from entering from the atmosphere side O to the sealed object side I.

[0083] As described above, in vehicles equipped with electric motors such as electric vehicles (EVs), electromagnetic noise may be generated by induced currents generated by the motor. Electromagnetic noise may also be generated by the on / off operation of an inverter for controlling the current supplied to an electric motor such as an electric motor, or by the induced voltage of the electric motor itself. In the sealing device 5, the main body 80 formed by molding the conductive elastic material of the conductive elastic body 6 forms a conductive circuit 8, and the electromagnetic noise transmitted to the shaft 101 flows to the housing 102. This makes it possible to prevent communication failures and malfunctions in electronic devices and electrolytic corrosion in metal parts.

[0084] When the shaft 101 rotates at high speed, the conducting lip 81 receives a force acting in a direction to break the contact between the conducting lip 81 and the shaft 101 due to the rotation of the shaft 101, but as described above, the conducting lip 81 has a shape that increases rigidity against an external force toward the outer periphery in the radial direction. Therefore, when the shaft 101 rotates at high speed, for example, when the shaft 101 rotates at a peripheral speed of 30 m / s or higher, a force acting in a direction to create a gap between the tip 81a of the conducting lip 81 and the outer periphery 101a of the shaft 101 may be generated, but in the sealing device 5, the conducting lip 81 has high rigidity against an external force toward the outer periphery in the radial direction. Therefore, when the shaft 101 rotates at high speed, a gap that interrupts electrical conduction is prevented from being generated between the contact surface (tip 81a) of the conducting lip 81 and the outer periphery 101a of the shaft 101. In this way, even when the shaft 101 rotates at high speed, the conductive performance between the tip 81a of the conductive lip 81 and the shaft 101 is maintained, and the flow rate of electromagnetic noise transmitted to the shaft 101 to the housing 102 can be maintained.

[0085] Therefore, as shown in Fig. 6, in the sealing device 5, the impedance of the conductive circuit 8 can be set to 0.01 Ω or more and 100 Ω or less when the shaft 101 of the electric motor rotates at a peripheral speed of 60 m / s or less. As a result, even when the shaft 101 of the electric motor rotates at high speed, the sealing device 5 can keep the impedance of the conductive circuit 8 in the range of 0.01 Ω or more and 100 Ω or less, and can suppress a decrease in conductivity. The impedance of the conductive circuit 8 of the sealing device 5 can also be measured in the same manner as the sealing device 1, and can be measured, for example, by an impedance measuring device 200 as shown in Fig. 7.

[0086] Moreover, according to the sealing device 5, when the sealing device 5 is installed in the annular space 104 between the shaft 101 and the housing 102, the sealing device 5 can be installed with the conductive elastic body portion 6 and the sealing device main body portion 7 assembled. The main body portion 80 including the conductive lip 81 of the conductive elastic body portion 6 is a molded body made of an elastic material having conductivity, so that deformation of the main body portion 80 is suppressed compared to a conventional conductive sliding member formed of a conductive brush or fiber. Therefore, the conductive elastic body portion 6 is easily attached to the sealing device main body portion 7, and is easily attached to the annular space 104 between the shaft 101 and the housing 102. Furthermore, since the conductive elastic body portion 6 has the cylindrical portion joint portion 74 and the annular portion joint portion 75, it is easy to attach and position the conductive elastic body portion 6 to the sealing device main body portion 7.

[0087] As described above, according to the sealing device 5 according to the third embodiment of the present invention, it is possible to maintain electrical conductivity even for the shaft 101 rotating at high speed.

[0088] Next, a sealing device 5A according to a fourth embodiment of the present invention will be described. Hereinafter, components having the same or similar functions as the conductive elastic body part 6 and the sealing device main body part 7 of the sealing device 5 according to the above-mentioned third embodiment will be denoted by the same reference numerals, and the description thereof will be omitted, and different components will be described.

[0089] FIG. 13 is a partial perspective view of a sealing device 5A according to a fourth embodiment of the present invention. The sealing device 5A includes a conductive elastic body portion 6A and a sealing device main body portion 7A. As shown in FIG. 13, the sealing device 5A is different from the above-mentioned sealing device 5 mainly in the configuration of the annular portion joining portion and the configuration of the annular portion joined portion. Specifically, the annular portion joining portion 75A of the conductive elastic body portion 6A is provided closer to the inner periphery side in the conductive elastic body portion 6A. Specifically, for example, as shown in FIG. 13, the annular portion joining portion 75A is formed in a position facing the cylindrical portion joining portion 74 or the cylindrical portion engaging portion 76 in the base portion 82 of the main body portion 80, and protrudes from the outer periphery side of the end portion I of the base portion 82 on the sealed object side. The sealing device main body portion 7A is in a form that can be joined to the annular portion joining portion 75A of the main body portion 80. 13, the base 62 of the seal body 60 of the sealing device main body 7A has a shape that is pressed against the annular portion joining portion 75A of the main body 80 toward the inner circumferential direction (arrow d direction) when the conductive elastic body portion 6A and the sealing device main body 7A are assembled. That is, the base 62 of the seal body 60 of the sealing device main body 7A is provided with an annular portion joined portion 68A that is formed to be pressed against the annular portion joining portion 75A of the main body 80 toward the inner circumferential direction (arrow d direction) when the conductive elastic body portion 6A and the sealing device main body 7A are assembled. Also, the seal body 60 of the sealing device main body 7A is not provided with a dust lip.

[0090] In a sealing device 5A according to a fourth embodiment of the present invention, as shown in Fig. 13, the base 62 of the seal body 60 of the sealing device main body 7A and the atmosphere side cover portion 64a are housed and engaged between the cylindrical portion joint portion 74 and the cylindrical portion engagement portion 76 of the conductive elastic body portion 6A and the annular portion joint portion 75A of the conductive elastic body portion 6A, so that the conductive elastic body portion 6A and the sealing device main body portion 7A are assembled to each other. The sealing device 5A according to the fourth embodiment of the present invention also functions in the same way as the above-mentioned sealing device 5, and can obtain the same effects.

[0091] Next, a sealing device 5B according to a fifth embodiment of the present invention will be described. Hereinafter, components having the same or similar functions as the conductive elastic body parts 6, 6A and the sealing device main body parts 7, 7A of the sealing devices 5, 5A according to the third and fourth embodiments will be denoted by the same reference numerals, and the description thereof will be omitted, and different components will be described.

[0092] FIG. 14 is a partial perspective view of a sealing device 5B according to a fourth embodiment of the present invention. The sealing device 5B includes a conductive elastic body portion 6B and a sealing device main body portion 7B. As shown in FIG. 14, the sealing device 5B is different from the above-mentioned sealing devices 5 and 5A mainly in the configuration of the main body portion of the conductive elastic body portion, the annular portion joining portion, and the annular portion joined portion configuration. For example, as shown in FIG. 14, the main body portion 80B of the conductive elastic body portion 6B is attached to the surface 72c of the reinforcing ring 70 facing the sealed object side I. Specifically, for example, as shown in FIG. 14, the connecting portion 83B of the main body portion 80B is attached to the inner peripheral portion of the surface 72c of the reinforcing ring 70, and an annular space (space 69) is formed between the outer peripheral end of the connecting portion 83B and the cylindrical portion 71 of the reinforcing ring 70. Also, as shown in FIG. 14, the main body portion 80B does not have a base portion, and a conductive lip 81 extends from the inner peripheral end of the connecting portion 83B.

[0093] 14, an annular recess is formed on the inner periphery of the atmosphere-side cover part 64a of the sealing device main body 7B, which is capable of accommodating the connecting part 83B of the main body 80B, and a lower part of the cylindrical part joined part 63b of the gasket part 63 protrudes to the atmosphere side O, forming a protruding part 64b, which is an annular protruding part, between the gasket part 63 and the atmosphere-side cover part 64a. As shown in FIG. 14, this protruding part 64b has a shape capable of being accommodated in the annular space 69 between the outer periphery side end (end 83b) of the connecting part 83B of the conductive elastic part 6B and the cylindrical part 71 of the reinforcing ring 70 when the conductive elastic part 6B and the sealing device main body 7B are assembled. Also, no dust lip is provided on the seal main body 60 of the sealing device main body 7B.

[0094] 14, the annular portion joining portion 75B is formed by an end 83b facing the outer periphery of the connecting portion 83B of the main body portion 80B of the conductive elastic body portion 6B, and the annular portion joining portion 68B is formed by an annular surface facing the inner periphery of the annular protruding portion 64b of the seal main body 60 of the sealing device main body portion 7B. In other words, when the conductive elastic body portion 6B and the sealing device main body portion 7B are assembled, the protruding portion 64b is accommodated in the space 69, and the end 83b (annular portion joining portion 75B) facing the outer periphery of the connecting portion 83B of the main body portion 80B radially compresses the inner periphery surface (annular portion joining portion 68B) of the protruding portion 64b between the cylindrical portion 71 of the reinforcing ring 70 of the conductive elastic body portion 6B. In this way, the annular portion joining portion 75B is in a form that can be joined to the annular portion joining portion 68B.

[0095] In the sealing device 5B according to the fifth embodiment of the present invention, as shown in Fig. 14, the protruding portion 64b of the seal body 60 of the sealing device main body 7B is accommodated and engaged between the cylindrical portion joint portion 74 and the cylindrical portion engaging portion 76 of the conductive elastic body portion 6B and the annular portion joint portion 75B of the conductive elastic body portion 6B (space 69), so that the conductive elastic body portion 6B and the sealing device main body 7B are assembled to each other. The sealing device 5B according to the fifth embodiment of the present invention also functions in the same way as the above-mentioned sealing device 5, and can obtain the same effects.

[0096] In the sealing device 5B, the material of the reinforcing ring 70 of the conductive elastomer portion 6B is a metal material, and the tubular portion 71 of the reinforcing ring 70 is configured to contact the inner surface 103a of the through hole 103 of the housing 102 when in use, and the conductive circuit 8 is formed by the main body portion 80B and the metallic reinforcing ring 70, as shown in Figure 14.

[0097] Although the embodiment of the present invention has been described above, the present invention is not limited to the sealing devices 1, 4, 5, 5A, and 5B according to the above-mentioned embodiment of the present invention, but includes all aspects included in the concept and scope of the claims of the present invention. In addition, each configuration may be appropriately and selectively combined so as to achieve at least a part of the above-mentioned problems and effects. For example, the shape, material, arrangement, size, etc. of each configuration in the above-mentioned embodiment may be appropriately changed depending on the specific use mode of the present invention. [Explanation of symbols]

[0098] 1,4,5,5A,5B...sealing device, 2,6,6A,6B...conductive elastic body portion, 3,8...conductive circuit, 7,7A,7B...sealing device main body portion, 10,15,50...reinforcing ring, 11,51...tubular portion, 11a,11c,51a...end portion, 11b,51b...outer peripheral surface, 12,52...bent portion, 12a,52a...end portion, 13,16,53...ring portion, 20,25,60...seal body, 21,61...seal portion, 22,62...base portion, 23, 63...gasket portion, 63a...contact portion, 63b...tubular portion to be joined, 63c...engaged portion, 24, 64...cover portion, 64a...atmospheric side cover portion, 64b...projection portion, 66...dust lip portion, 68, 68A, 68B...annular portion to be joined, 69...space, 30...conductive lip portion, 31...conductive lip, 32...contact surface, 33...grease groove, 34...connecting groove, 35...garter spring, 36...grease supply portion, 40, 65...seal lip , 41, 48... seal lip, 42... sealed object side, 43... atmospheric side, 44... tip, 45... thread groove, 46... thread projection, 47, 67... garter spring, 49... seal surface, 70... reinforcing ring, 71... cylindrical portion, 71a... end, 71b... surface, 72... annular portion, 72a, 72c... surface, 72b... end, 73... sealing device joint, 74... cylindrical portion joint, 75, 75A, 75B... annular portion joint, 76... cylindrical portion engagement portion, 80, 80 B...main body, 81...conductive lip, 81a...tip, 82...base, 83, 83B...connecting portion, 83a...end, 83b...end, 101...shaft, 101a...outer circumferential surface, 102...housing, 103...through hole, 103a...inner circumferential surface, 104...space, 200...impedance measuring device, 201...impedance analyzer, 202, 203...conductive member, I...sealed object side, G...grease, O...atmospheric side, S...space, x...axis

Claims

[Claim 1] A sealing device for sealing an annular space between an inner circumferential member and an outer circumferential member that rotate relative to each other, It comprises a conductive elastic body portion having an annular member around its axis, which is formed from a conductive elastic material, The conductive elastic body portion is capable of contacting the inner circumferential member and the outer circumferential member, and is capable of forming a conductive circuit between the inner circumferential member and the outer circumferential member. In the relative rotation at a peripheral speed of 60 m / s or less, the impedance of the conductive circuit is 0.01 Ω or more and 100 Ω or less. A sealing device characterized by the following features.

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