JP2020183776A - Sealing device - Google Patents

Abstract

To provide a sealing device which is small in wear of a lip, and small in torque imparted to a rotating body.SOLUTION: The sealing device seals a clearance between a housing and a rotating body 4 arranged in a hole of the housing, and partitions an internal space of the housing and an atmosphere side. The sealing device has an attachment cylinder portion attached to the housing, a seal cylinder portion 12 arranged inside the attachment cylinder portion in a radial direction, a connecting cylinder portion 14 connecting the attachment cylinder portion and the seal cylinder portion to each other, a main-seal lip 16, and a sub-seal lip 18. These seal lips protrude from an internal circumferential surface of the seal cylinder portion. The main seal lip is constantly brought into slidable contact with an external circumferential surface of the rotating body, however, the sub-seal lip is brought into slidable contact with the external circumferential surface of the rotating body when pressure is imparted to the seal cylinder portion from the outside. A minimum thickness A of an end of the seal cylinder portion at the atmosphere side is equal to or less than a half of a length B from the connecting cylinder portion in an axial line direction of the sealing device up to a lip edge of the main lip.SELECTED DRAWING: Figure 2

Description

The present invention relates to a sealing device.

The link (for example, arm) of the articulated robot can be rotated directly by a motor, but can also be rotated from the motor via a gear reducer. An oil seal used in a gear reducer for driving a link of an articulated robot is known (Patent Document 1). This oil seal seals the gap between the rotating shaft located on the case and the case.

Japanese Unexamined Patent Publication No. 2011-89609

For this type of oil seal, it is desirable that the lip wear is small and the torque applied to the rotating body is small.

Therefore, the present invention provides a sealing device in which the wear of the lip is small and the torque applied to the rotating body is small.

The sealing device according to an aspect of the present invention seals a gap between a housing and a rotating body arranged in a hole provided in the housing, and seals the internal space of the housing and the atmosphere side. A device, which is a mounting cylindrical portion mounted on the housing, a sealed cylindrical portion arranged radially inside the mounting cylindrical portion, an end portion of the mounting cylindrical portion on the atmospheric side, and an atmospheric side of the sealed cylindrical portion. A connecting ring portion that connects the ends of the seal cylinder portion in the radial direction, a main seal lip that protrudes from the inner peripheral surface of the seal cylinder portion and is slidably contacted with the outer peripheral surface of the rotating body, and the seal cylinder portion. It has a sub-seal lip that protrudes from the inner peripheral surface, is arranged on the atmosphere side of the main seal lip, and has an inner diameter larger than that of the main seal lip. The sub-seal lip does not come into contact with the outer peripheral surface of the rotating body when no pressure is applied, and can slide on the outer peripheral surface of the rotating body when pressure is applied to the seal cylindrical portion from the outside. Be brought into contact. The seal cylindrical portion, the main seal lip and the sub seal lip are formed only from an elastic material. The mounting cylindrical portion and the connecting annular portion are formed of the elastic material and the rigid material. The minimum thickness of the end portion of the seal cylinder portion on the atmosphere side is ½ or less of the length from the connecting annular portion to the lip edge of the main seal lip in the axial direction of the sealing device.

In this embodiment, the secondary seal lip does not contact the outer peripheral surface of the rotating body when no pressure is applied, but can slide on the outer peripheral surface of the rotating body when pressure is applied to the seal cylinder portion from the outside. The main seal lip, which is brought into contact with the rotating body and is always slidably contacted with the outer peripheral surface of the rotating body, suppresses an increase in the binding force applied to the rotating body. Therefore, the wear of the main seal lip is reduced, and the increase in torque applied to the rotating body is suppressed. The connecting ring portion is formed of an elastic material and a rigid material and has high rigidity, but the seal cylindrical portion supported by the connecting ring portion is formed only of the elastic material and has low rigidity and has a seal. The thickness of the end of the cylinder on the atmosphere side is small. Therefore, when pressure is applied to the seal cylindrical portion from the outside, the seal cylindrical portion is likely to be deformed radially inward together with the sub-seal lip, and is easily brought into slidable contact with the outer peripheral surface of the rotating body. Therefore, it is possible to effectively suppress an increase in the binding force exerted by the main seal lip on the rotating body.

It is a partial cross-sectional view of the sealing device which concerns on 1st Embodiment of this invention. It is an enlarged cross-sectional view of the seal cylinder part, the main seal lip and the sub seal lip of the sealing device of FIG. It is the enlarged sectional view of the seal cylinder part, the main seal lip and the sub seal lip in the state of applying pressure. A table showing the parameters and simulation results used in the analysis simulation that calculated the relationship between the position of the secondary seal lip with respect to the main seal lip in the initial state and the contact width of the main seal lip with the rotating shaft in the pressure-applied state. is there. It is a graph which shows the result of the analysis simulation. It is a partial cross-sectional view of the sealing device which concerns on 2nd Embodiment of this invention.

Hereinafter, various embodiments according to the present invention will be described with reference to the accompanying drawings. Drawing scales are not always accurate and some features may be exaggerated or omitted.

The sealing device according to the embodiment is used to seal grease in the internal space of the housing of the gear reducer for driving the link of the articulated robot.

First Embodiment As shown in FIG. 1, the sealing device 1 according to the first embodiment includes a housing 2 of a gear reducer and a rotating shaft (rotating body) 4 arranged in a hole 2A provided in the housing 2. The gap between the housing 2 and the housing 2 is sealed to separate the internal space of the housing 2 from the atmosphere side. The rotating shaft 4 is a shaft for driving a robot link (for example, an arm). The rotary shaft 4 is rotatably supported by a bearing (not shown) and is coaxially arranged in the hole 2A. The rotating shaft 4 may be the final final output shaft of the gear reducer, but may be another rotating body.

The rotary shaft 4 has a columnar shape, the holes 2A have a circular cross section, and the sealing device 1 has an annular shape, but only the left half of them is shown in FIG.

The housing 2 and the rotating shaft 4 are shown by virtual lines. In the used state in which the sealing device 1 is installed in the gap between the housing 2 and the rotating shaft 4, the sealing device 1 is compressed and deformed in the radial direction.

The sealing device 1 has a composite structure having an elastic ring 6 and a rigid ring 8. The elastic ring 6 is made of an elastic material, for example, an elastomer. The rigid ring 8 is made of a rigid material, for example metal, to reinforce the elastic ring 6. The rigid ring 8 has an L-shaped cross section, and has a sleeve 8A and an annular portion 8B extending radially inward from the end of the sleeve 8A on the atmosphere side.

The sealing device 1 has a mounting cylindrical portion 10, a sealing cylindrical portion 12, a connecting ring portion 14, a main sealing lip 16, a secondary sealing lip 18, and a dust strip 20.

The mounting cylindrical portion 10 is mounted on the housing 2. The mounting method is not limited, but for example, the mounting cylindrical portion 10 may be tightly fitted into the hole 2A. The mounting cylindrical portion 10 is composed of an elastic ring 6 and a rigid ring 8. More specifically, in the mounting cylindrical portion 10, the elastic ring 6 is fixed to the entire outer peripheral surface of the sleeve 8A of the rigid ring 8 and is also fixed to the entire inner peripheral surface of the sleeve 8A of the rigid ring 8. Therefore, the mounting cylindrical portion 10 has an elastic portion 10a that covers the entire outer peripheral surface of the sleeve 8A and an elastic portion 10b that covers the entire inner peripheral surface of the sleeve 8A. However, it is not essential to cover the inner peripheral surface of the sleeve 8A with an elastic material.

The seal cylindrical portion 12 is composed of only the elastic ring 6, and is arranged radially inside the mounting cylindrical portion 10. The seal cylindrical portion 12 overlaps the mounting cylindrical portion 10 in the radial direction.

The connecting annular portion 14 connects the end portion of the mounting cylindrical portion 10 on the atmospheric side and the end portion of the seal cylindrical portion 12 on the atmospheric side in the radial direction. The connecting annular portion 14 is composed of an elastic ring 6 and a rigid ring 8. More specifically, in the connecting annulus portion 14, the elastic ring 6 is fixed to the entire surface of the annulus portion 8B of the rigid ring 8 on the atmosphere side, and the surface of the annulus portion 8B of the rigid ring 8 on the internal space side. It is also stuck to a part of. Therefore, the connecting annular portion 14 has an elastic portion 14a that covers the entire surface of the annular portion 8B on the atmosphere side, and an elastic portion 14b that covers a part of the surface of the annular portion 8B on the internal space side.

The main seal lip 16 is a protrusion protruding from the inner peripheral surface of the seal cylindrical portion 12, and has a grease-side inclined surface 16a arranged on the internal space side, an atmospheric-side inclined surface 16b arranged on the atmospheric side, and a grease side. It has a lip edge 16c extending in the circumferential direction at the boundary between the inclined surface 16a and the atmospheric side inclined surface 16b. The grease-side inclined surface 16a has the shape of the side surface of the truncated cone, and is inclined so as to be separated from the rotating shaft 4 as the distance from the lip edge 16c increases. The atmospheric side inclined surface 16b also has the shape of the side surface of the truncated cone, and is inclined so as to be separated from the rotation axis 4 as the distance from the lip edge 16c increases. In the used state in which the sealing device 1 is installed in the gap between the housing 2 and the rotating shaft 4, the lip edge 16c of the main seal lip 16 and its vicinity are always slidably contacted with the outer peripheral surface of the rotating shaft 4. Be done.

Spiral ribs 17a and 17b are formed on the atmospheric side inclined surface 16b of the main seal lip 16. As described in Japanese Patent No. 4702517, the spiral ribs 17a and 17b provide a pumping action of returning the grease leaking from the lip edge 16c to the atmosphere side to the internal space as the rotating shaft 4 rotates. However, the spiral ribs 17a and 17b are not indispensable.

The secondary seal lip 18 is also a protrusion protruding from the inner peripheral surface of the seal cylindrical portion 12. The secondary seal lip 18 is arranged closer to the atmosphere than the main seal lip 16, and has an inner diameter larger than the inner diameter of the main seal lip 16. The secondary seal lip 18 is located at the boundary between the grease-side inclined surface 18a arranged on the internal space side, the atmospheric-side inclined surface 18b arranged on the atmospheric side, and the grease-side inclined surface 18a and the atmospheric-side inclined surface 18b. It has a lip edge 18c extending in the circumferential direction. The grease-side inclined surface 18a has the shape of the side surface of the truncated cone, and is inclined so as to be separated from the rotating shaft 4 as the distance from the lip edge 18c increases. The atmospheric side inclined surface 18b also has the shape of the side surface of the truncated cone, and is inclined so as to be separated from the rotation axis 4 as the distance from the lip edge 18c increases. When the sealing device 1 is installed in the gap between the housing 2 and the rotating shaft 4 and no pressure is applied, the secondary seal lip 18 does not come into contact with the outer peripheral surface of the rotating shaft 4. That is, there is a gap between the sub-seal lip 18 and the outer peripheral surface of the rotating shaft 4. However, when pressure is applied to the seal cylindrical portion 12 from the outside, the lip edge 18c of the sub-seal lip 18 and its vicinity are slidably brought into contact with the outer peripheral surface of the rotary shaft 4.

The dust strip 20 is a truncated cone-shaped plate that extends obliquely inward in the radial direction and toward the atmosphere from the inner peripheral surface of the connecting annular portion 14. The dust strip 20 has a role of suppressing the invasion of foreign matter (including water or dust) from the atmosphere side to the internal space side. In this embodiment, the dust strip 20 is not brought into contact with the rotating shaft 4 in order to reduce the torque applied to the rotating shaft 4 by the sealing device 1. However, in order to further reduce the intrusion of foreign matter, the tip of the dust strip 20 may be slidably brought into contact with the outer peripheral surface of the rotary shaft 4.

The main seal lip 16, the secondary seal lip 18, and the dust strip 20 are composed of only the elastic ring 6.

A peripheral groove 21 is formed on the outer peripheral surface of the seal cylindrical portion 12, and a garter spring 22 is arranged in the peripheral groove 21. The garter spring 22 presses the main seal lip 16 and the dust strip 20 inward in the radial direction.

Each of FIGS. 2 and 3 is an enlarged cross-sectional view of the seal cylindrical portion 12, the main seal lip 16, and the sub seal lip 18. FIG. 2 shows an initial state in which the sealing device 1 is not installed in the gap between the housing 2 and the rotating shaft 4, and no pressure is applied to the sealing cylindrical portion 12 from the outside.

On the other hand, FIG. 3 shows a state in which the sealing device 1 is installed in the gap between the housing 2 and the rotating shaft 4, and a pressure is applied to the sealing cylindrical portion 12 from the outside (hereinafter, this). The state is called "pressure applied state"). Specifically, in FIG. 3, the seal cylindrical portion 12, the main seal lip 16 and the sub seal lip 18 in the initial state (state in FIG. 2) are shown by imaginary lines, and are displaced inward in the radial direction by the pressure P. The seal cylinder portion 12, the main seal lip 16, and the sub seal lip 18 in the state are shown by solid lines. When the pressure of the grease in the internal space increases, the pressure P is applied to the seal cylindrical portion 12 from the outside. Specifically, when grease is present around the seal cylindrical portion 12, pressure P is applied from the grease to the seal cylindrical portion 12. Even when there is no grease around the seal cylindrical portion 12, pressure P is applied to the seal cylindrical portion 12 from the air around the seal cylindrical portion 12 pressed by the grease.

When the sealing device 1 is deployed in the gap between the housing 2 and the rotating shaft 4, the main seal lip 16 is always in contact with the outer peripheral surface of the rotating shaft 4, so that even if there is no pressure P, compared to the initial state. Transforms. Further, the main seal lip 16 is pressed against the outer peripheral surface of the rotating shaft 4 by the pressure P and is greatly deformed. Therefore, the binding force exerted by the main seal lip 16 on the rotating shaft 4 increases. The secondary seal lip 18 does not come into contact with the outer peripheral surface of the rotary shaft 4 when the pressure P is not applied even in the used state, but when the pressure P is applied to the seal cylindrical portion 12 from the outside, the rotary shaft 4 It is slidably contacted with the outer peripheral surface of the main seal lip 16 and suppresses an increase in the binding force applied to the rotating shaft 4. Therefore, the wear of the main seal lip 16 is reduced, and the increase in torque applied to the rotating shaft 4 is suppressed.

As shown in FIG. 2, the minimum thickness A of the end portion of the seal cylindrical portion 12 on the atmosphere side is the main seal lip 16 from the connecting annular portion 14 (specifically, the elastic portion 14b) in the axial direction of the sealing device 1. It is less than 1/2 of the length B up to the lip edge 16c. The connecting annular portion 14 is formed of an elastic material and a rigid material and has high rigidity, but the sealed cylindrical portion 12 supported by the connecting annular portion 14 is formed only of the elastic material and has low rigidity. The minimum thickness A of the end portion of the seal cylindrical portion 12 on the atmospheric side is small. Therefore, when the pressure P is applied to the seal cylindrical portion 12 from the outside, the seal cylindrical portion 12 is easily deformed inward in the radial direction together with the sub-seal lip 18, and is slidably brought into contact with the outer peripheral surface of the rotary shaft 4. Cheap. Therefore, it is possible to effectively suppress an increase in the binding force exerted by the main seal lip 16 on the rotating shaft 4.

Further, as shown in FIGS. 2 and 3, the sub-seal lip 18 is arranged in a region overlapping the garter spring 22 in the radial direction. In FIG. 2, the region C overlaps the garter spring 22 in the radial direction, and the lip edge 18c of the sub-seal lip 18 is arranged in this region C. The compressive force of the garter spring 22 causes the secondary seal lip 18 to slidably contact the outer peripheral surface of the rotating shaft 4, as compared to the case where the secondary seal lip 18 is not arranged in a region that overlaps the garter spring 22 in the radial direction. Easy to get. Therefore, it is possible to effectively suppress an increase in the binding force exerted by the main seal lip 16 on the rotating shaft 4.

In order to investigate the suitable positional relationship of the sub-seal lip 18 with respect to the main seal lip 16, the inventor performed an analysis simulation using the finite element method (FEM) to perform the main seal lip 16 in the initial state (state of FIG. 2). The relationship between the position of the secondary seal lip 18 and the contact width W of the main seal lip 16 with respect to the rotating shaft 4 in the pressure-applied state (state of FIG. 3) was calculated. Considering the torque applied to the rotating shaft 4 by the sealing device 1 and the wear of the main sealing lip 16, it is preferable that the contact width W is small.

In the analysis simulation, the pressure P in the pressure-applied state was set to 0.04 MPa. The outer diameter D of the rotating shaft 4 was set to 49.8 mm. The inner diameter d ₁ of the lip edge 16c of the main seal lip 16 in the initial state was set to 49.4 mm, which is smaller than the outer diameter D of the rotating shaft 4.

Then, the distance (inter-lip distance) L between the lip edge 16c of the main seal lip 16 and the lip edge 18c of the sub-seal lip 18 in the axial direction of the sealing device 1 in the initial state, and the sub-seal lip 18 in the initial state. The inner diameter d ₂ of the lip edge 18c was changed. The boundary between the atmospheric side inclined surface 16b of the main seal lip 16 and the grease side inclined surface 18a of the sub seal lip 18 in the initial state, that is, the inner diameter d _{3 of the} valley portion 24 is changed to be larger than the inner diameter d ₂ of the lip edge 18c. did.

FIG. 4 shows the parameters used in the analysis simulation and the simulation results. With the change of the inner diameter d ₂ of the lip edge 18c in the initial state, the radial distance g between the lip edge 16c and the lip edge 18c in the initial state changes, and the lip edge 18c and the rotating shaft 4 in the initial state change. The gap G between them also changes. The ratio of the radial distance g between the lip edge 16c and the lip edge 18c to the axial distance L in the initial state also changes. θ is the inclination angle of the generatrix of the virtual cone connecting the lip edge 16c and the lip edge 18c in the initial state with respect to the axis of the sealing device 1.

As is clear from FIG. 4, the larger the distance L between the lips in the axial direction in the initial state, the larger the contact width W of the main seal lip 16 with the rotating shaft 4 in the pressure-applied state. The relationship between the change in tan θ and the contact width W was not clear.

FIG. 5 shows the relationship between the distance between lips in the axial direction in the initial state and the contact width W in the pressure-applied state. As is clear from FIG. 5, the rate of increase of the contact width W is small when the distance L between lips is 0.8 mm to 1.2 mm, but the rate of increase of the contact width W increases when the distance L between lips exceeds 1.2 mm. large. That is, when the distance L between lips exceeds 1.2 mm, the contact width W of the main seal lip 16 with the rotating shaft 4 in the used state becomes remarkably large, and the torque applied to the rotating shaft 4 and the main seal lip 16 Wear increases significantly. When the distance L between lips is 1.2 mm or less, it is possible to suppress an increase in torque applied to the rotating shaft 4 and wear of the main seal lip 16. Therefore, it is preferable that the distance from the lip edge 16c of the main seal lip 16 to the lip edge 18c of the secondary seal lip 18 in the axial direction of the sealing device 1 in the initial state is 1.2 mm or less.

Second Embodiment FIG. 6 is a partial cross-sectional view of the sealing device 30 according to the second embodiment of the present invention. In FIG. 6, the same reference numerals are used to show the components already described, and these components will not be described in detail.

The sealing device 30 has an auxiliary seal 32 in addition to the basic configuration similar to that of the sealing device 1 according to the first embodiment. The auxiliary seal 32 is removable from the basic configuration and is arranged inside the mounting cylindrical portion 10 of the basic configuration.

The auxiliary seal 32 has a composite structure having an elastic ring 34 and a rigid ring 36. The elastic ring 34 is made of an elastic material, such as an elastomer. The rigid ring 36 is made of a rigid material, for example metal, to reinforce the elastic ring 34. The rigid ring 36 has a substantially L-shaped cross section, and has a sleeve 36A and an annular portion 36B extending radially inward from an end portion of the sleeve 36A on the internal space side. The sleeve 36A of the rigid ring 36 is fitted into the elastic portion 10b of the mounting cylindrical portion 10 by a tightening method.

The elastic ring 34 has an auxiliary lip 38 arranged radially inside the annular portion 36B of the rigid ring 36. The auxiliary lip 38 is arranged on the internal space side of the main seal lip 16 having the basic configuration. The tip of the auxiliary lip 38 is slidably brought into contact with the outer peripheral surface of the rotating shaft 4.

According to this embodiment, the auxiliary seal 32 prevents the grease arranged in the internal space from leaking to the atmosphere side. However, since there may be a minute gap between the auxiliary lip 38 and the outer peripheral surface of the rotating shaft 4, when the pressure of the grease in the internal space increases, the pressure P may be applied to the seal cylindrical portion 12 from the outside. Further, as the auxiliary lip 38 is worn, the grease in the internal space can get over the auxiliary lip 38 and enter the atmosphere side, so that the pressure P can be applied to the seal cylindrical portion 12 from the outside also in this case. Similar to the first embodiment, by forming the seal cylindrical portion 12, the main seal lip 16, and the sub seal lip 18, the increase in the binding force exerted by the main seal lip 16 on the rotating shaft 4 is suppressed, and the main seal lip 16 is suppressed. It is possible to reduce the wear of the rotating shaft 4 and suppress an increase in the torque applied to the rotating shaft 4.

Modified Examples Although the present invention has been illustrated and described with reference to preferred embodiments of the present invention, those skilled in the art can change the form and details without departing from the scope of the invention described in the claims. It will be understood that it is possible. Such changes, modifications and modifications should be within the scope of the present invention.

For example, in the above embodiment, the sealing device is applied to the gear reducer housing 2 and the housing 2 in order to seal the grease in the internal space of the gear reducer housing for driving the link of the articulated robot. The gap between the rotating shaft 4 arranged in the provided hole 2A is sealed. However, the sealing device may be used to seal the grease in the interior space of the housing of another gear reducer.

Further, the sealing device seals a gap between the housing and a rotating body that rotates at a low speed in a hole provided in the housing in order to seal the grease in the internal space of the housing of the device other than the gear reducer. May be used. For example, a sealing device may be used to seal the gap between the rotating shaft of the turntable of a precision machine and the housing of the rotating shaft. Alternatively, a sealing device may be used to seal the gap between the rotating shaft of the swivel camera or swivel blower and the housing of the swivel shaft.

Another component (eg, a sleeve) may be placed around the rotating shaft 4 so that the main seal lip 16 is slidably contacted with the outer peripheral surface of this component, and the secondary seal lip 18 is pressured. When not in contact with the outer peripheral surface of the component, the seal cylindrical portion 12 may be slidably contacted with the outer peripheral surface of the component when pressure is applied from the outside. In this case, the combination of the rotating shaft 4 and this component can be regarded as a rotating body.

Aspects of the invention are also described in the numbered clauses below.

Clause 1. A sealing device that seals a gap between a housing and a rotating body arranged in a hole provided in the housing and separates the internal space of the housing from the atmosphere side.
The mounting cylinder to be mounted on the housing and
A seal cylindrical portion arranged radially inside the mounting cylindrical portion,
A connecting ring portion that connects the end portion of the mounting cylinder portion on the atmosphere side and the end portion of the seal cylinder portion on the atmosphere side in the radial direction,
A main seal lip that protrudes from the inner peripheral surface of the seal cylindrical portion and is slidably contacted with the outer peripheral surface of the rotating body.
It has a secondary seal lip that protrudes from the inner peripheral surface of the seal cylindrical portion, is arranged on the atmosphere side of the main seal lip, and has an inner diameter larger than that of the main seal lip.
The sub-seal lip does not come into contact with the outer peripheral surface of the rotating body when no pressure is applied, and is slidable on the outer peripheral surface of the rotating body when pressure is applied to the seal cylindrical portion from the outside. Be contacted,
The seal cylinder, the main seal lip and the sub seal lip are made of elastic material only.
The mounting cylindrical portion and the connecting annular portion are formed of the elastic material and the rigid material.
The minimum thickness of the end portion of the seal cylinder portion on the atmosphere side is ½ or less of the length from the connecting ring portion to the lip edge of the main seal lip in the axial direction of the sealing device. Sealing device.

Clause 2. It further has a garter spring arranged around the seal cylinder.
The sealing device according to Clause 1, wherein the secondary seal lip is arranged in a region that overlaps the garter spring in the radial direction.

According to this clause, the compressive force of the garter spring causes the secondary seal lip to slidably contact the outer peripheral surface of the rotating body, as compared to the case where the secondary seal lip is not located in the area where it radially overlaps the garter spring. Easy to be forced. Therefore, it is possible to effectively suppress an increase in the binding force exerted by the main seal lip on the rotating body.

Clause 3. The sealing device according to Clause 1 or 2, wherein the distance from the lip edge of the main sealing lip to the lip edge of the secondary sealing lip in the axial direction of the sealing device is 1.2 mm or less.

When this distance exceeds 1.2 mm, the contact width of the main seal lip with the rotating body in the used state becomes remarkably large, and the torque applied to the rotating body and the wear of the main seal lip increase remarkably. When this distance is 1.2 mm or less, an increase in torque applied to the rotating body and wear of the main seal lip can be suppressed.

Clause 4. It also has an auxiliary seal located inside the mounting cylinder.
The auxiliary seal is arranged on the sleeve fitted in the mounting cylinder portion in the radial direction from the sleeve and on the internal space side from the main seal lip, and is slidably brought into contact with the outer peripheral surface of the rotating body. The sealing device according to any one of Articles 1 to 3, wherein the sealing device has a lip.

According to this clause, the auxiliary seal prevents the grease placed in the internal space from leaking to the atmosphere.

1 Sealing device 2 Housing 2A Hole 4 Rotating shaft (rotating body)
10 Mounting Cylindrical Part 12 Seal Cylindrical Part 14 Connecting Ring Part 16 Main Seal Lip 16c Lip Edge 18 Secondary Seal Lip 18c Lip Edge 22 Garter Spring 30 Sealing Device 32 Auxiliary Seal 38 Auxiliary Lip

Claims (4)

A sealing device that seals a gap between a housing and a rotating body arranged in a hole provided in the housing and separates the internal space of the housing from the atmosphere side.
The mounting cylinder to be mounted on the housing and
A seal cylindrical portion arranged radially inside the mounting cylindrical portion,
A connecting ring portion that connects the end portion of the mounting cylinder portion on the atmosphere side and the end portion of the seal cylinder portion on the atmosphere side in the radial direction,
A main seal lip that protrudes from the inner peripheral surface of the seal cylindrical portion and is slidably contacted with the outer peripheral surface of the rotating body.
It has a secondary seal lip that protrudes from the inner peripheral surface of the seal cylindrical portion, is arranged on the atmosphere side of the main seal lip, and has an inner diameter larger than that of the main seal lip.
The sub-seal lip does not come into contact with the outer peripheral surface of the rotating body when no pressure is applied, and can slide on the outer peripheral surface of the rotating body when pressure is applied to the seal cylindrical portion from the outside. Be contacted,
The seal cylinder, the main seal lip and the sub seal lip are made of elastic material only.
The mounting cylindrical portion and the connecting annular portion are formed of the elastic material and the rigid material.
The minimum thickness of the end portion of the seal cylinder portion on the atmosphere side is ½ or less of the length from the connecting ring portion to the lip edge of the main seal lip in the axial direction of the sealing device. Sealing device. It further has a garter spring arranged around the seal cylinder.
The sealing device according to claim 1, wherein the sub-seal lip is arranged in a region overlapping the garter spring in the radial direction. The sealing device according to claim 1 or 2, wherein the distance from the lip edge of the main sealing lip to the lip edge of the secondary sealing lip in the axial direction of the sealing device is 1.2 mm or less. It also has an auxiliary seal located inside the mounting cylinder.
The auxiliary seal is arranged on the sleeve fitted in the mounting cylinder portion in the radial direction from the sleeve and on the internal space side from the main seal lip, and is slidably brought into contact with the outer peripheral surface of the rotating body. The sealing device according to any one of claims 1 to 3, further comprising a lip.

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