JP2020063792A - Sealing device - Google Patents

Abstract

To secure conduction between an electric motor housing and a rotating shaft in an electric motor at low volume resistivity.SOLUTION: A sealing device is an oil seal (1) having a conductive elastic body part (30) having lips (32, 33) slidably contacting with a rotating shaft (41), arranged between the rotating shaft (41) and a housing (42), and sealing a lubrication material in the device while suppressing the intrusion of foreign matters from the outside of the device, and a conductive reinforcing ring (20) formed at the elastic body part (30) integrally therewith, and contacting with an internal peripheral face of the housing (42). The reinforcing ring (20) has a first conduction face (101) contacting with the elastic body part (30) at the rotating shaft (41) side, and a second conduction face (102) contacting with the reinforcing ring (20) at the housing (42) side, and conductivity between the first conduction face (101) and the second conduction face (102) is higher than that of the elastic body part (30).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealing device that seals between a rotating shaft connected to a motor and a housing.

Generally, in EVs (Electric Vehicles) and HVs (Hybrid Vehicles), an oil seal is provided between the rotary shaft of the motor and the housing in order to prevent leakage of the lubricant sealed inside the machine to the outside. A sealing device is provided.
In such EV and HV, electromagnetic noise is generated by the induced current generated in the motor, which may affect the AM radio of the car audio.

Patent Document 1, which is an example of a conventional technique, aims to reduce generation of electromagnetic noise from an electric motor, and in a power transmission system of an electric vehicle, a metal electric motor housing and a rotating shaft in the electric motor are electrically connected to each other. There is disclosed a technique in which electromagnetic noise induced in a rotating shaft is released to a metal motor housing by conducting the electric field.
In particular, in FIG. 4 of Patent Document 1, the electric motor housing (14) and the rotating shaft (18) in the electric motor (10) are electrically connected by an oil seal (86) made of conductive rubber. , A technique of releasing electromagnetic noise induced in a rotating shaft to a metal motor housing is disclosed.

JP-A-2000-244180

  According to the above-mentioned conventional technique, it is possible to ensure electrical conduction between the rotary shaft connected to the motor and the housing, but there is room for improvement in volume resistivity.

  The present invention has been made in view of the above, and an object of the present invention is to smoothly conduct electricity between a rotary shaft connected to a motor and a housing at low cost and in a small space.

  The present invention which solves the above-mentioned problems and achieves the object is a sealing device which is arranged between a rotary shaft connected to a motor and a housing and seals the inside and the outside of the machine. A conductive elastic body portion that has a lip that movably contacts and that is disposed between the rotary shaft and the housing and that seals a lubricant inside the machine while suppressing the intrusion of foreign matter from the outside of the machine; A conductive reinforcing ring formed integrally with the elastic body portion and in contact with the inner peripheral surface of the housing, wherein the reinforcing ring has a first conducting surface in contact with the elastic body portion on the rotating shaft side and the housing. The sealing device has a second conductive surface that is in contact with the reinforcing ring on the side, and the conductivity between the first conductive surface and the second conductive surface is higher than that of the elastic body portion.

  In the sealing device having the above structure, it is preferable that the first conducting surface is surrounded by a joint surface between the reinforcing ring and the elastic body portion.

  In the sealing device having the above configuration, the metal of the reinforcing ring is in contact with the elastic body portion on the first conductive surface, and the metal of the reinforcing ring is in contact with the housing on the second conductive surface. It is preferable.

  Advantageous Effects of Invention According to the present invention, there is an effect that conduction between a rotary shaft connected to a motor and a housing can be smoothly performed at low cost and in a small space.

It is sectional drawing which shows the mounting state of the oil seal which is the sealing device which concerns on embodiment. It is a figure explaining the flow of the induced current from a rotating shaft to a housing in the oil seal which is a sealing device concerning an embodiment. It is a figure which shows the example of the part which exposes the metal of a reinforcement ring in the oil seal which is the sealing device which concerns on embodiment.

Embodiments of the present invention will be described below with reference to the drawings.
However, the present invention should not be limitedly interpreted by the description of the following embodiments.

<Embodiment>
FIG. 1 is a cross-sectional view showing a mounted state of an oil seal 1 which is a sealing device according to this embodiment.
The oil seal 1 shown in FIG. 1 is a sealing device that is arranged between the rotary shaft 41 and the housing 42 to seal the inside A and the outside B of the machine.
The rotating shaft 41 shown in FIG. 1 is connected to a motor (not shown) to rotate, and the housing 42 is grounded.
The oil seal 1 shown in FIG. 1 is provided with a seal portion 10 to prevent foreign matter from entering the inside A from the outside B and prevent the lubricant in the inside A from leaking to the outside B while at the same time preventing rotation of the rotary shaft. Conduction between 41 and the housing 42 can be smoothly performed.

The seal portion 10 includes a reinforcing ring 20 and an elastic body portion 30, and the reinforcing ring 20 and the elastic body portion 30 are integrally formed.
Further, the seal portion 10 is attached to an inner peripheral surface 42a which is a surface on the inner peripheral side (in the direction of arrow d) of the housing 42.

The reinforcing ring 20 is a conductive metal ring formed of metal with the axis x of the rotating shaft 41 as the center.
Examples of the material of the reinforcing ring 20 include stainless steel and cold rolled steel (SPCC).
The reinforcing ring 20 can be formed by pressing or forging.

The elastic body portion 30 is a substantially annular conductive elastic body formed of an elastic material with the axis x of the rotating shaft 41 as the center.
As a material of the elastic body portion 30, synthetic rubber can be exemplified.
Here, examples of the synthetic rubber include nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM).

Further, the elastic body portion 30 can be molded by crosslinking using a molding die.
More specifically, the elastic body portion 30 has an uncrosslinked rubber material placed in contact with the reinforcing ring 20 provided in the molding die, and heats the closed space in the molding die while being sandwiched by the molding die. And, by applying pressure, it is formed integrally with the reinforcing ring 20 by crosslinking.
An adhesive is applied between the reinforcing ring 20 and the elastic body portion 30.

The reinforcing ring 20 includes a cylindrical portion 20a, an outer peripheral side disc portion 20b, a taper portion 20c, and an inner peripheral side disc portion 20d, and the cylindrical portion 20a, the outer peripheral side disc portion 20b, the tapered portion 20c, and the inner peripheral side disc. The part 20d is integrally formed.
Further, the outer peripheral side disc portion 20b, the taper portion 20c, and the inner peripheral side disc portion 20d form a flange portion having a substantially S-shape as a whole.

The cylindrical portion 20a is a cylindrical portion that extends in a direction substantially parallel to the axis x, and is fitted so as to contact the inner peripheral surface 42a of the housing 42.
The outer peripheral side disc portion 20b is a hollow disc-shaped portion formed from the outer end (direction of arrow a) of the cylindrical portion 20a toward the inner peripheral side (direction of arrow d).
The taper portion 20c is a hollow disc-shaped portion formed from the inner peripheral side (arrow d direction) end of the outer peripheral disc portion 20b toward the inner peripheral side (arrow d direction) and the inner side (arrow b direction). Is.
The inner peripheral side disc portion 20d is a hollow disc-shaped portion formed from the inner peripheral side (arrow d direction) end of the tapered portion 20c toward the inner peripheral side (arrow d direction).
It should be noted that the cylindrical portion 20a may have a shape that bulges toward the outer peripheral side (direction of arrow c) in the unmounted state.

Further, before mounting the reinforcing ring 20, the metal on the outer contact surface 20d1 of the inner peripheral side disk portion 20d and the outer peripheral surface 20a2 of the cylindrical portion 20a is exposed by mechanical means or chemical means.
This is because a part of the adhesive applied between the reinforcing ring 20 and the elastic body portion 30 also remains on the outer peripheral surface 20a2 of the reinforcing ring 20, and conduction is obstructed by this adhesive. .
Here, polishing and cutting can be exemplified as the mechanical means, and immersion in a solution capable of removing the adhesive can be exemplified as the chemical means.
Examples of the solution capable of removing such an adhesive material include an alkaline cleaner or a solvent.
As a result, the metal of the reinforcing ring 20 is in contact with the elastic body portion 30 at the outer contact surface 20d1 to ensure conduction between the reinforcing ring 20 and the elastic body portion 30, and the metal of the reinforcing ring 20 is connected to the housing 42 at the outer peripheral surface 20a2. The reinforcement ring 20 and the housing 42 are electrically connected to each other.

In addition, in FIG. 1, the surface of the reinforcing ring 20 where the base metal and the elastic body portion 30 contact is not limited to the outer contact surface 20d1 shown in FIG. It is preferably surrounded by the joint surface.
When the surface of the reinforcing ring 20 where the base metal and the elastic body portion 30 are in contact is not surrounded by the joint surface between the reinforcing ring 20 and the elastic body portion 30, the reinforcing ring 20 and the elastic body portion 30 are separated from each other. This is because there is a fear that this may be prevented.

  The elastic body portion 30 includes lip covering portions 30a, 30b, 30c, 30d, a lip waist portion 30e, and lips 31, 32, 33, and the reinforcing ring 20 is outside (arrow a direction) and outer peripheral side (arrow c direction). Is formed integrally with the reinforcing ring 20 so as to cover a part thereof and the inner peripheral side (direction of arrow d).

The lip coating portion 30a covers a part of the cylindrical portion 20a of the reinforcing ring 20 on the outer peripheral side (direction of arrow c).
The lip covering portion 30b covers the outer peripheral disk portion 20b of the reinforcing ring 20 from the outside (direction of arrow a).
The lip covering portion 30c covers the taper portion 20c of the reinforcing ring 20 and is a base portion of the lip 31.
The lip covering portion 30d covers the inner peripheral side disk portion 20d of the reinforcing ring 20 from the outside (direction of arrow a).
The lip waist portion 30e is a base portion of the lips 32 and 33, which is located in the vicinity of an end portion of the inner peripheral side disk portion 20d of the reinforcing ring 20 on the inner peripheral side (arrow d direction).
Further, the lip 31 slidably contacts a structure (not shown), the lips 32 and 33 slidably contact the rotary shaft 41, and the lips 31 and 32 prevent foreign matter from entering the machine A from outside the machine B. While suppressing, the lip 33 prevents the lubricant in the in-machine A from leaking to the outside B.
If the elastic body portion 30 can prevent foreign matter from entering the inside A from the outside B while preventing the lubricant in the inside A from leaking to the outside B, the lips 31, 32 ,. Not all 33 may be provided, and the elastic body portion 30 may include at least one lip.

FIG. 2 is a diagram illustrating the flow of the induced current from the rotary shaft 41 to the housing 42 in the oil seal 1 that is the sealing device according to the present embodiment.
Here, the surface where the reinforcing ring 20 on the rotary shaft 41 side is in contact with the lip waist portion 30e is the first conducting surface 101, and the surface where the reinforcing ring 20 on the housing side is in contact with the housing 42 is the second conducting surface 102. And
Further, the metal of the reinforcing ring 20 is in contact with the elastic body portion 30 on the first conductive surface 101, and the metal of the reinforcing ring 20 is in contact with the housing 42 on the second conductive surface 102.
As shown in FIG. 2, an induced current generated by a motor (not shown) connected to the rotary shaft 41 flows from the lips 32, 33 of the elastic body portion 30 to the lip waist portion 30e, and the current reaching the lip waist portion 30e is The current flowing from the first conducting surface 101 to the reinforcing ring 20 having a volume resistivity lower than that of the elastic body portion 30, that is, having higher conductivity, and flowing through the reinforcing ring 20 flows from the second conducting surface 102 to the housing 42. .

As described above, in FIG. 1, the surface of the reinforcing ring 20 where the metal and the elastic body portion 30 are in contact with each other is surrounded by the joint surface between the reinforcing ring 20 and the elastic body portion 30, so that the first conducting surface is formed. 101 is surrounded by the joint surface between the reinforcing ring 20 and the elastic body portion 30.
With such a configuration, peeling between the reinforcing ring 20 and the elastic body portion 30 can be prevented.

In the conventional configuration, the induced current generated in the motor flows through the elastic body portion 30 from the rotating shaft 41 to the housing 42, so that the elastic body portion 30 has a large volume resistivity.
Therefore, electromagnetic noise may be generated by this induced current and the car audio AM radio may be affected.
However, as described above, the volume resistivity of the induced current can be lowered by providing the conduction path passing through the reinforcing ring 20.
Since the conductive path can be provided by exposing the bare metal of the existing reinforcing ring 20, the conductive path can be secured at low cost and in a small space.

In addition, in the present embodiment, the metal of the reinforcing ring 20 is exposed by mechanical means or chemical means, but the present invention is not limited to this.
Conduction may be secured by covering the exposed bare metal portion of the reinforcing ring 20 with a masking tape before applying the adhesive and peeling off the masking tape before the subsequent mounting.
By using the masking tape, electrical continuity can be secured without using mechanical means and chemical means.

  In the present embodiment, the portion of the reinforcing ring 20 where the bare metal is exposed is limited to a specific portion as long as it is a contact surface where the inner peripheral side disk portion 20d and the elastic body portion 30 come into contact with each other, as described above. It is not something that will be done.

FIG. 3 is a diagram showing an example of a portion of the reinforcing ring 20 that exposes the base metal in the oil seal 1 that is the sealing device according to the present embodiment.
FIG. 3 shows an outer contact surface 20d1, an inner peripheral contact surface 20d2, and an inner contact surface 20d3.
The outer contact surface 20d1 is a contact surface where the inner peripheral disk portion 20d and the elastic body portion 30 contact outside the inner peripheral disk portion 20d.
The inner peripheral side contact surface 20d2 is a contact surface where the inner peripheral side disk portion 20d and the elastic body portion 30 contact on the inner peripheral side of the inner peripheral side disk portion 20d.
The inner contact surface 20d3 is a contact surface where the inner peripheral disk portion 20d and the elastic body portion 30 contact each other inside the inner peripheral disk portion 20d.

  When the bare metal of the reinforcing ring 20 is exposed at the outer contact surface 20d1, the outer contact surface 20d1 is surrounded by the joint surface between the reinforcing ring 20 and the elastic body portion 30, so that the adhesive strength is strong and the rotating contact Since the position is less likely to be affected by the movement of the lips 31, 32, 33, it is possible to maintain high adhesive strength between the inner peripheral side disc portion 20d and the elastic body portion 30.

  When the metal of the reinforcing ring 20 is exposed at the inner peripheral side contact surface 20d2, the inner peripheral side contact surface 20d2 is affected by the movements of the lips 31, 32, 33 during the rotation operation, but the reinforcing ring 20 and the elastic body are not affected. Since it is surrounded by the joint surface with the portion 30, the adhesive strength is strong.

When the base metal of the reinforcing ring 20 is exposed at the inner contact surface 20d3, the inner contact surface 20d3 is affected by the movement of the lips 31, 32, 33 during the rotation operation, and the reinforcing ring 20 and the elastic body portion 30 are joined together. Not surrounded by faces.
Therefore, the portion of the reinforcing ring 20 where the metal is exposed is preferably the inner peripheral contact surface 20d2 rather than the inner contact surface 20d3, and more preferably the outer contact surface 20d1 than the inner peripheral contact surface 20d2.

  As described above, according to the present embodiment, conduction between the rotary shaft connected to the motor and the housing can be smoothly performed at low cost and in a small space.

1 Oil seal 10 Seal part 20 Reinforcement ring 20a Cylindrical part 20a2 Outer peripheral surface 20b Outer peripheral side disk part 20c Tapered part 20d Inner peripheral side disk part 20d1 Outer contact surface 20d2 Inner peripheral contact surface 20d3 Inner contact surface 30 Elastic body parts 30a, 30b , 30c, 30d Lip coating portion 30e Lip waist portions 31, 32, 33 Lip 41 Rotating shaft 42 Housing 42a Inner peripheral surface 101 First conducting surface 102 Second conducting surface

Claims (3)

A sealing device arranged between a rotary shaft connected to a motor and a housing to seal the inside and outside of the machine,
A conductive elastic member which has a lip slidably contacting the rotary shaft and is disposed between the rotary shaft and the housing to seal foreign matter from the outside of the machine while sealing a lubricant inside the machine. Body part,
A conductive reinforcing ring formed integrally with the elastic body portion and in contact with the inner peripheral surface of the housing,
The reinforcing ring has a first conducting surface that contacts the elastic body portion on the rotating shaft side and a second conducting surface that contacts the reinforcing ring on the housing side,
A sealing device in which conductivity between the first conductive surface and the second conductive surface is higher than that of the elastic body portion.   The sealing device according to claim 1, wherein the first conductive surface is surrounded by a joint surface between the reinforcing ring and the elastic body portion. In the first conductive surface, the metal of the reinforcing ring contacts the elastic body portion,
The sealing device according to claim 1 or 2, wherein the metal of the reinforcing ring is in contact with the housing on the second conductive surface.

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