JP2023168666A - sealing device - Google Patents

Abstract

To provide a sealing device capable of suppressing a large amount of leakage of a fluid.SOLUTION: A sealing device 10 is mounted on an annular space S formed between a shaft 7 and a housing 8, and prevents a liquid on one side in an axial direction from leaking to the other side in the axial direction. The sealing device 10 includes: a fixing part 14 fixed to the housing 8; a first lip 11 having a first lip tip part 16 which comes into contact by having a crush margin on an outer peripheral surface 7a of the shaft; a second lip 12 having a second lip tip part 17 positioned further on the other side in the axial direction than the first lip tip part 16; and a third lip 13 having a third lip tip part 18 positioned further on the other side in the axial direction than the second lip tip part 17. A crush margin on the outer peripheral surface 7a of the shaft of the second lip tip part 17 is smaller than the crush margin on the outer peripheral surface 7a of the shaft of the first lip tip part 16. The third lip tip part 18 comes into non-contact with the outer peripheral surface 7a of the shaft. Between the second lip 12 and the third lip 13, a recess part 19 recessed to the outside in a radial direction is provided.SELECTED DRAWING: Figure 1

Description

The present invention relates to a sealing device.

A sealing device is provided between the rotating shaft and a portion of the housing that supports the shaft to prevent fluid such as lubricating oil from leaking to the outside. The sealing device has a fixed part attached to the housing and a lip extending from the fixed part and capable of elastic deformation. Patent Document 1 discloses a sealing device as described above.

Japanese Patent Application Publication No. 2019-210998

The lip of the sealing device has a lip tip that slides into contact with the outer peripheral surface of the rotating shaft. Particularly when the shaft rotates at high speed, surface burn or abnormal wear may occur at the tip of the lip, and lubricating oil, which is the object of sealing, may seep out from between the lip tip and the shaft, resulting in leakage. Although such leakage of lubricating oil is slight, if it continues, the amount of leakage will gradually increase and may lead to a large amount of leakage.

Therefore, an object of the present disclosure is to provide a sealing device that can suppress a large amount of fluid from leaking.

(1) The sealing device of the present disclosure is a sealing device that is installed in an annular space formed between a shaft and a housing and prevents liquid on one side in the axial direction from leaking to the other side in the axial direction. a first lip extending from the fixing part toward the shaft and having a first lip tip that contacts an outer peripheral surface of the shaft; and a first lip extending from the fixing part toward the shaft. a second lip provided and having a second lip tip located on the other side in the axial direction than the first lip tip; a third lip having a third lip tip located on the other side in the direction, the third lip tip is not in contact with the outer circumferential surface of the shaft, and the second lip and the third lip A recessed portion recessed radially outward is provided between them.

According to the sealing device, even if the liquid passes through the first lip tip, the liquid can be retained in the space formed between the first lip and the second lip. Further, even if the liquid passes through the tip of the second lip, the recess between the second lip and the third lip makes it difficult for the liquid to flow beyond the third lip to the other side in the axial direction.
The third lip tip is spaced apart from the outer peripheral surface of the shaft. Therefore, although the liquid that has passed through the second lip may adhere to the second lip due to surface tension, for example, it is less likely to adhere to the third lip than the second lip. Therefore, it is difficult for the liquid to flow beyond the third lip to the other side in the axial direction.
As described above, it is possible to suppress a large amount of fluid from leaking.

(2) Preferably, the second lip has, on its inner periphery, a second protrusion or a second groove that guides the liquid to one side in the axial direction as the shaft rotates. According to the configuration, even if liquid passes through the second lip tip and remains in the recess, the liquid can be returned to one side in the axial direction.

(3) Preferably, the first lip has, on its inner periphery, a first protrusion or a first groove that guides the liquid to one side in the axial direction as the shaft rotates. According to the configuration, even if liquid passes through the first lip tip and remains in the space between the first lip and the second lip, it is possible to return the liquid to one side in the axial direction. Become.

(4) Preferably, in the sealing device according to any one of (1) to (3), the first lip tip contacts the outer peripheral surface of the shaft with a crushing margin, and The second lip tip contacts the outer peripheral surface of the shaft with a crushing margin, has a crushing margin of zero on the outer peripheral surface of the shaft, or does not contact the outer peripheral surface of the shaft. According to the above configuration, when the crushing margin of the second lip tip is zero or the second lip tip is not in contact with the shaft, the increase in rotational resistance of the shaft due to the second lip tip is particularly prevented. It is possible to suppress it. The third lip tip is not in contact with the outer circumferential surface of the shaft, and no rotational resistance of the shaft is caused by the third lip tip. In particular, if the crushing margin at the tip of the second lip is zero, it is possible to make it difficult for the liquid in the space between the first lip and the second lip to flow toward the other side in the axial direction.

(5) Preferably, in the sealing device according to any one of (1) to (4), the fixing portion includes a metal ring and a rubber coating that covers at least an inner peripheral portion of the metal ring. The second lip and the third lip each extend from the common covering part. According to the configuration, the radial positions of the second lip tip and the third lip tip with respect to the outer circumferential surface of the shaft are easily determined.

(6) Preferably, in the sealing device according to (5) above, the third lip is located on one side in the axial direction from the side surface on the other side in the axial direction of the covering portion. According to the configuration, the third lip does not protrude beyond the covering portion toward the other side in the axial direction. The sealing device is prevented from interfering with other members.

(7) Preferably, in the sealing device according to (5) or (6), the second lip tip portion is radially inside a portion of the covering portion of the fixing portion to which the first lip is connected. exists in According to the configuration, a space recessed toward the other side in the axial direction is formed between the portion of the covering portion that is connected to the first lip and the second lip tip. When liquid passes through the first lip tip and exists in the recessed space, it is difficult for the liquid to flow to the other side in the axial direction.

According to the sealing device of the present disclosure, even if fluid oozes out between the first lip and the shaft, it is possible to suppress a large amount of fluid from leaking.

FIG. 1 is a sectional view of a sealing device according to a first embodiment. FIG. 2 is an explanatory diagram showing a cross section and a part of the inner peripheral side of the sealing device. FIG. 3 is a sectional view showing another embodiment (second embodiment) of the sealing device. FIG. 4 is a sectional view showing still another embodiment (third embodiment) of the sealing device. FIG. 5 is an enlarged view illustrating the functions of the second lip and the third lip. FIG. 6 is an enlarged view illustrating the functions of the second lip and the third lip. FIG. 7 is an enlarged view showing a comparative example.

[About the first embodiment]
FIG. 1 is a sectional view of a sealing device according to a first embodiment. FIG. 1 shows the shaft 7 viewed from the side. FIG. 1 is a sectional view taken along a plane including the centerline C of the shaft 7. The sealing device 10 is installed in an annular space S formed between the shaft 7 and a part of the housing 8 .

The shaft 7 has a cylindrical shape and is rotatably supported by a bearing or the like (not shown) provided in the housing 8. The shaft 7 rotates around the center line C. The center line C of the shaft 7 and the center line of the sealing device 10 coincide. The sealing device 10 is used for, for example, a motor, a transmission, etc., but is also applicable to other devices.

Each direction of the sealing device 10 of the present disclosure will be defined. The direction along the center line C and the direction parallel to the center line C are defined as axial directions. The direction perpendicular to the center line C is defined as the radial direction. The direction along the circle centered on the center line C is defined as the circumferential direction.
In the annular space S, the right side in FIG. 1 is defined as one axial side (first axial side), and the left side in FIG. 1 is defined as the other axial side (second axial side). In this embodiment, lubricating oil is present on one side of the sealing device 10 in the axial direction. The other axial side of the sealing device 10 is on the atmosphere side. In the following description, one axial side will be referred to as the "sealed fluid side", and the other axial side will be referred to as the "atmospheric side".

The sealing device 10 prevents the lubricating oil on the sealed fluid side from leaking into the atmosphere in the annular space S. For this purpose, the sealing device 10 includes a fixing part 14, a first lip 11, a second lip 12, and a third lip 13. Note that the liquid to be prevented from leaking by the sealing device 10 may be other than lubricating oil.

The fixed part 14 is an annular part fixed to the housing 8. In the embodiment shown in FIG. 1, the fixing part 14 includes a first metal ring 21, a first covering part 23 made of rubber that covers the first metal ring 21, a second metal ring 22, and a second metal ring 22. It has a second covering part 24 made of rubber that covers the. One first seal 26 is constituted by the first metal ring 21, the first covering portion 23, and the first lip 11. One second seal 27 is constituted by the second metal ring 22, the second covering portion 24, the second lip 12, and the third lip 13. One sealing device 10 is configured by combining the first seal 26 and the second seal 27.

The cylindrical outer peripheral part 21a of the first metal ring 21 is fitted into the housing 8 via the outer peripheral part 23b of the first covering part 23, and the first seal 26 is fixed to the housing 8. The cylindrical outer peripheral portion 22b of the second metal ring 22 is fitted into the housing 8, and the second seal 27 is fixed to the housing 8. The first covering part 23, the second covering part 24, the first lip 11, the second lip 12, and the third lip 13 are made of an elastic material such as rubber.

The first lip 11 is annular. The first lip 11 is provided to extend from the inner circumferential portion 23a of the first covering portion 23 of the fixing portion 14 toward the shaft 7 side. The first lip 11 has a first lip tip 16 that contacts the outer circumferential surface 7a of the shaft 7 with a crushing margin. An annular spring 30 is provided on the outer peripheral side of the first lip tip 16. The spring 30 presses the first lip tip 16 against the shaft 7 by its elastic restoring force. The first lip 11 has a lip base 15 that connects the inner peripheral part 23a of the first covering part 23 and the first lip tip 16.

The first lip tip portion 16 has a first inclined surface 31 whose diameter increases toward the sealed fluid side, and a second inclined surface 32 whose diameter increases toward the atmosphere side. The lip base 15 has a third inclined surface 33 extending from the second inclined surface 32 . The intersection of the first inclined surface 31 and the second inclined surface 32 becomes the lip tip 16a of the first lip tip 16. The lip tip 16a contacts the outer circumferential surface 7a of the shaft 7, and the crushing margin is generated at the lip tip 16a.

FIG. 2 is an explanatory diagram showing a cross section and a part of the inner peripheral side of the sealing device 10. The first lip 11 has a first protrusion 38 on its inner periphery that guides the lubricating oil L toward the sealing fluid side as the shaft 7 rotates. The first protrusion 38 is provided on the inner peripheral side of the first lip 11 in a range excluding the lip tip 16a and the first inclined surface 31. In the form shown in FIG. 2, the first protrusion 38 is formed on the second inclined surface 32 (excluding the lip tip 16a), the third inclined surface 33, and the inner circumferential surface 23c of the first covering portion 23. ing. The function of the first protrusion 38 will be explained later.

The second lip 12 will be explained with reference to FIGS. 1 and 2. The second lip 12 is annular. The second lip 12 is provided to extend from the inner circumferential portion 24a of the second covering portion 24 of the fixing portion 14 toward the shaft 7 side. The second lip 12 has a second lip tip 17 located closer to the atmosphere than the first lip tip 16 . The second lip tip portion 17 has a fourth inclined surface 34 whose diameter increases toward the sealed fluid side, and a fifth inclined surface 35 whose diameter increases toward the atmosphere side.

The intersection of the fourth inclined surface 34 and the fifth inclined surface 35 becomes the lip tip 17a of the second lip tip 17. The lip tip 17a is close to the outer peripheral surface 7a of the shaft 7. The second lip tip 17 (lip tip 17a) can come into contact with the outer circumferential surface 7a of the shaft 7. However, the crushing allowance on the outer peripheral surface 7a of the shaft 7 of the second lip tip 17 is smaller than the crushing allowance on the outer peripheral surface 7a of the shaft 7 of the first lip tip 16. Specifically, in this embodiment, the crushing margin of the second lip tip portion 17 on the outer circumferential surface 7a of the shaft 7 is zero. Note that the crushing allowance is zero, but before the sealing device 10 starts to be used, the crushing allowance may exist at a small positive value, and after a while after the rotation of the shaft 7 is started, the lip tip 17a may be worn out, and the crushing allowance may become zero.

Alternatively, the crushing margin of the second lip tip portion 17 on the outer circumferential surface 7a of the shaft 7 may be a negative value. In other words, the second lip tip 17 is not in contact with the outer circumferential surface 7a of the shaft 7, and there may be a gap between the lip tip 17a and the outer circumferential surface 7a of the shaft 7. However, it is preferable that a minute gap (a gap of less than 1 mm in the radial direction) be formed between the lip tip 17a and the outer circumferential surface 7a of the shaft 7.

The second lip tip portion 17 exists on the radially inner side of the first covering portion 23 (inner peripheral portion 23a) to which the first lip 11 is connected. With this configuration, a space K3 recessed toward the atmosphere is formed between the first covering portion 23 (inner peripheral portion 23a) and the second lip tip portion 17.

The second lip 12 has a second protrusion 39 on its inner periphery that guides lubricating oil toward the sealing fluid side as the shaft 7 rotates. As shown in FIG. 2, the second protrusion 39 is provided on the fifth inclined surface 35 on the inner peripheral side of the second lip 12. As shown in FIG. The second protrusion 39 is provided in a range from the lip tip 17a to the recess 19. The function of the second protrusion 39 will be explained later.

The third lip 13 is annular. The third lip 13 is provided to extend from the inner circumferential portion 24a of the second covering portion 24 of the fixed portion 14 toward the shaft 7 side. The third lip 13 has a third lip tip 18 located closer to the atmosphere than the second lip tip 17 . The third lip tip portion 18 has a sixth inclined surface 36 whose diameter increases toward the sealed fluid side, and a seventh inclined surface 37 whose diameter increases toward the atmosphere side.

The intersection of the sixth inclined surface 36 and the seventh inclined surface 37 becomes the lip tip 18a of the third lip tip 18. The lip tip 18a is not in contact with the outer peripheral surface 7a of the shaft 7. A gap is provided between the lip tip 18a and the outer peripheral surface 7a of the shaft 7 over the entire circumference. The third lip tip 18 does not contact the outer circumferential surface 7a of the shaft 7 even if a manufacturing error occurs within the dimensional tolerance of the third lip 13.

A recess 19 is provided between the second lip 12 and the third lip 13. The recess 19 is a portion recessed outward in the radial direction, and is a V-shaped groove continuous in the circumferential direction. The recessed portion 19 is a portion between the fifth inclined surface 35 and the sixth inclined surface 36.

In the embodiment shown in FIG. 1, the fixing part 14 includes a second metal ring 22 and a second covering part 24 made of rubber that covers at least an inner peripheral part 22a of the second metal ring 22. Each of the second lip 12 and the third lip 13 is provided extending from one common second covering portion 24 (inner peripheral portion 24a). Specifically, the second lip 12 is provided to protrude from the first portion of the inner peripheral portion 24a located on the sealing fluid side. The third lip 13 is provided to protrude from a second portion of the inner peripheral portion 24a located on the atmosphere side.

With this configuration, the radial positions of the second lip tip 17 and the third lip tip 18 with respect to the outer circumferential surface 7a of the shaft 7 are easily determined. In other words, if the fixing part 14 is fixed to the housing 8, the positional relationship between the second lip tip part 17 and the outer circumferential surface 7a of the shaft 7 (the relationship in which the crushing margin is zero) is appropriately set, and the The three lip tip portions 18 are not in contact with the outer circumferential surface 7a of the shaft 7.

The third lip 13 is located closer to the sealing fluid side than the side surface 41 of the second covering part 24 on the atmosphere side. That is, the third lip 13 does not protrude further toward the atmosphere than the second covering portion 24 .

[About the functions of the first protrusion 38 and the second protrusion 39]
In FIG. 2, the first protrusion 38 is schematically shown by a line, and the second protrusion 39 is schematically shown by a line.
A plurality of first protrusions 38 are provided on the inner periphery of the first lip 11 at intervals in the circumferential direction. The first protrusion 38 has a shape that protrudes radially inward from the second inclined surface 32.
A plurality of second protrusions 39 are provided on the inner periphery of the second lip 12 at intervals in the circumferential direction. The second protrusion 39 has a shape that protrudes radially inward from the fifth inclined surface 35.

When the shaft 7 rotates, air around the shaft 7 flows in the same direction as the rotation direction of the shaft 7. When the lubricating oil L is attached to the first protruding ridge 38, the lubricating oil L is pushed by the air flowing in the circumferential direction, and the sealing oil L moves along the first protruding ridge 38 to approach the lip tip 16a. (see dotted arrow in Figure 2). Thereby, the lubricating oil L adhering to the second inclined surface 32 is guided to the vicinity of the lip tip 16a.

By continuing the pumping action by the first protrusion 38, the lubricating oil L can be returned to the sealing fluid side from the lip tip 16a. The first protrusion 38 is arranged circumferentially and axially in accordance with the rotating direction of the shaft 7 so that the lubricating oil L is guided to the sealed fluid side by being pushed by the air flowing circumferentially as described above. It is provided at an angle with respect to the direction.

When the shaft 7 rotates, air around the shaft 7 flows in the same direction as the rotation direction of the shaft 7. When the lubricating oil L adheres to the second protruding rim 39, the lubricating oil L is pushed by the air flowing in the circumferential direction, and the sealing fluid moves along the second protruding rim 39 to approach the lip tip 17a. (see dotted arrow in Figure 2). Thereby, the lubricating oil L adhering to the recess 19 and the fifth inclined surface 35 is guided to the vicinity of the lip tip 17a.

By continuing the pumping action of the second protrusion 39, the lubricating oil L can be returned to the sealing fluid side from the lip tip 17a. The second protrusion 39 is arranged circumferentially and axially in accordance with the rotating direction of the shaft 7 so that the lubricating oil L is guided to the sealed fluid side by being pushed by the air flowing circumferentially as described above. It is provided at an angle with respect to the direction.

In the case of the sealing device 10 shown in FIG. They overlap in the radial direction with the parts in between. In the first embodiment shown in FIG. 1, the first seal 26 and the second seal 27 are integrally attached to the housing 8.

[About other forms of sealing device 10]
FIG. 3 is a sectional view showing another form (second embodiment) of the sealing device 10. In the case of the second embodiment, the cylindrical outer peripheral portion 22b of the second metal ring 22 does not overlap the first metal ring 21 in the radial direction. The outer peripheral portion 22b of the second metal ring 22 is provided extending from the annular portion 22c of the second metal ring 22 toward the atmosphere. A rubber covering portion 42 covers the outer peripheral portion 22b. The outer peripheral portion 22bc is fitted into the housing 8 via the covering portion 42.

In the case of the second embodiment, the first seal 26 and the second seal 27 can be attached to the housing 8 separately. Alternatively, the sealing device 10 can be configured by adding the second seal 27 to the existing first seal 26.

[About another form of sealing device 10]
FIG. 4 is a sectional view showing still another form (third embodiment) of the sealing device 10. In the case of the third embodiment, the fixing part 14 includes one metal ring 28 and a rubber covering part 29 that covers the metal ring 28. A first lip 11 , a second lip 12 , and a third lip 13 are provided extending from the inner peripheral portion 29 a of the covering portion 29 . In the case of the third embodiment, handling of the sealing device 10 and attachment to the housing 8 is facilitated.

In the third embodiment, the second lip tip portion 17 exists on the radially inner side of the covering portion 29 (inner peripheral portion 29a) to which the first lip 11 is connected. A space K3 recessed toward the atmosphere is formed between the covering portion 29 (inner peripheral portion 29a) and the second lip tip portion 17.

In each of the second embodiment and the third embodiment, the same components as in the first embodiment are given the same reference numerals, and descriptions of the same components will be omitted.

[About the sealing device 10 of each embodiment]
The sealing device 10 of each of the first to third embodiments includes a first lip 11, a second lip 12, and a third lip 13, which are provided extending from a fixed part 14 fixed to the housing 8 toward the shaft 7. Be prepared. The first lip 11 has a first lip tip 16 that contacts the outer peripheral surface 7a of the shaft 7. The second lip 12 has a second lip tip 17 located closer to the atmosphere than the first lip tip 16 . The third lip 13 has a third lip tip 18 located closer to the atmosphere than the second lip tip 17 . The third lip tip 18 is not in contact with the outer peripheral surface 7a of the shaft 7. A recess 19 recessed radially outward is provided between the second lip 12 and the third lip 13.

According to the sealing device 10 having the above-mentioned configuration, even if lubricating oil present on the sealing fluid side of the sealing device 10 passes through the first lip tip 16, there is no leakage between the first lip 11 and the second lip 12. It becomes possible to retain the lubricating oil in the first space K1 formed in the first space K1. Further, even if the lubricating oil passes through the second lip tip 17, the recess 19 between the second lip 12 and the third lip 13 prevents the lubricating oil from flowing beyond the third lip 13 to the atmosphere.

5 and 6 are enlarged views illustrating the functions of the second lip 12 and the third lip 13. FIG. 5 shows a state where the rotation of the shaft 7 is stopped (stopped state). FIG. 6 shows a state in which the shaft 7 is rotating. As shown in FIG. 5, the lubricating oil L that has passed through the second lip tip 17 toward the atmosphere (left side in FIG. 5) is captured by the recess 19. As shown in FIG. 6, when the shaft 7 rotates, the lubricating oil L in the recess moves toward the lip tip 17a of the second lip tip 17 due to the function of the second protrusion 39. As shown in FIG. Therefore, the lubricating oil L is difficult to leak beyond the third lip 13 to the atmosphere side.

FIG. 7 is an enlarged view showing a comparative example. FIG. 7 shows a case where the third lip tip 18 contacts the outer circumferential surface 7a of the shaft 7 similarly to the second lip tip 17. In the case of this comparative example, the lubricating oil L that has passed through the second lip tip 17 to the atmosphere side (left side in FIG. 7) is moved between the lip tip 18a of the third lip tip 18 and the outer circumferential surface 7a of the shaft 7 due to surface tension. It may be caught between. Then, there is a high possibility that the lubricating oil L will eventually leak out of the sealing device 10 over the lip tip 18a to the atmosphere side.

On the other hand, as shown in FIGS. 5 and 6, according to the sealing device 10 of each of the first to third embodiments, the third lip tip 18 is separated from the outer circumferential surface 7a of the shaft 7. . Therefore, as shown in FIG. 6, although the lubricating oil L that has passed through the second lip tip 17 may adhere to the second lip 12 due to surface tension, for example, It is more difficult to adhere than No. 17. Therefore, the lubricating oil L is difficult to flow beyond the third lip 18 to the atmosphere.
As described above, it is possible to suppress a large amount of lubricating oil from leaking.

According to the sealing device 10 of each of the first to third embodiments, since the crushing allowance of the second lip tip 17 is smaller than the crushing allowance of the first lip tip 16, the axis of the second lip tip 17 is It is possible to suppress an increase in rotational resistance and heat generation. The third lip tip 18 is not in contact with the outer circumferential surface 7a of the shaft 7, and rotational resistance of the shaft 7 by the third lip tip 18 does not occur.

In the sealing device 10 of each of the first to third embodiments (for example, see FIG. 1), as described above, the crushing margin of the second lip tip portion 17 on the outer circumferential surface 7a of the shaft 7 is zero. Alternatively, the second lip tip 17 is not in contact with the outer circumferential surface 7a of the shaft 7. Therefore, the function of suppressing an increase in the rotational resistance of the shaft 7 by the second lip tip portion 17 is further enhanced. In particular, if the crushing margin of the second lip tip 17 is set to zero, it is possible to make it difficult for the lubricating oil in the first space K1 between the first lip 11 and the second lip 12 to flow toward the atmosphere.
Alternatively, the second lip tip portion 17 may contact the outer circumferential surface 7a of the shaft 7 with a crushing margin. Also in this case, it is possible to make it difficult for the lubricating oil in the first space K1 to flow toward the atmosphere.

As explained with reference to FIG. 2, the second lip 12 has a second protrusion 39 on its inner periphery that guides the lubricating oil L toward the sealing fluid side as the shaft 7 rotates. As shown in FIGS. 5 and 6, even if the lubricating oil L in the first space K1 passes through the second lip tip 17 and remains in the recess 19, if the shaft 7 rotates, the lubricating oil L will be lubricated. It becomes possible to return the oil L to the sealing fluid side.

Note that instead of the second protrusion 39, a second groove may be formed on the inner periphery of the second lip 12. In this case as well, when the shaft 7 rotates, the lubricating oil is pushed by the air flowing in the circumferential direction and returned to the sealing fluid side along the second groove.

As explained with reference to FIG. 2, the first lip 11 has a first protrusion 38 on its inner periphery that guides the lubricating oil L toward the sealing fluid side as the shaft 7 rotates. Even if the lubricating oil present on the sealing fluid side of the sealing device 10 passes through the first lip tip 16 and remains in the first space K1 between the first lip 11 and the second lip 12, When the shaft 7 rotates, the lubricating oil can be returned to the sealing fluid side of the lip tip 16a of the first lip tip portion 16.

Note that instead of the first protrusion 38, a first groove portion may be formed on the inner periphery of the first lip 11. In this case as well, when the shaft 7 rotates, the lubricating oil is pushed by the air flowing in the circumferential direction and returned to the sealing fluid side along the first groove.

In the sealing device 10 of the first embodiment (FIG. 1) and the second embodiment (FIG. 3), the fixing part 14 includes the second metal ring 22 and the rubber covering at least the inner peripheral part 22a of the second metal ring 22. It has a second covering part 24 made of. Each of the second lip 12 and the third lip 13 is provided extending from one common second covering portion 24 . According to this configuration, the radial positions of the second lip tip 17 and the third lip tip 18 with respect to the outer circumferential surface 7a of the shaft 7 are easily determined.

In the sealing device 10 of the third embodiment (FIG. 4), the fixing portion 14 includes a metal ring 28 and a rubber covering portion 29 that covers at least an inner peripheral portion 28a of the metal ring 28. Each of the second lip 12 and the third lip 13 is provided extending from one common covering portion 29 . A first lip 11 is also provided extending from the covering portion 29 . According to this configuration, the radial positions of the first lip tip 11, the second lip tip 17, and the third lip tip 18 with respect to the outer circumferential surface 7a of the shaft 7 are easily determined.

In the sealing device 10 of the first embodiment (FIG. 1) and the second embodiment (FIG. 3), the third lip 13 is located closer to the sealing fluid than the side surface 41 on the atmosphere side of the second covering portion 24 (FIGS. 1 and 3). 3, it is located on the right side). In the sealing device 10 of the third embodiment (FIG. 4), the third lip 13 is located closer to the sealing fluid side (on the right side in FIG. 4) than the side surface 41 of the covering portion 29 on the atmosphere side. According to this configuration, the third lip 13 does not protrude further toward the atmosphere than the second covering portion 24 (covering portion 29). The sealing device 10 is prevented from interfering with other members.

In the sealing device 10 of each of the first to third embodiments, the second lip tip portion 17 is located radially inside the portion of the second covering portion 24 (covering portion 29) to which the first lip 11 is connected. . Therefore, a space K3 recessed toward the atmosphere is formed between the portion of the second covering portion 24 (covering portion 29) that is connected to the first lip 11 and the second lip tip portion 17. For example, in FIG. 1, when lubricating oil on the sealing fluid side of the sealing device 10 passes through the first lip tip 16 and exists in the recessed space K3 of the first space K1, the lubricating oil is on the atmosphere side. It is difficult to flow.

As described above, according to the sealing device 10 of each of the embodiments, even if lubricant oil oozes between the first lip 11 and the shaft 7, it is possible to suppress a large amount of lubricant oil from leaking. It is possible.

〔others〕
A third protrusion similar to the second protrusion 39 may be provided on the inner periphery of the third lip 13. The third protrusion is provided on at least one of the sixth inclined surface 36 and the seventh inclined surface 37. In this case, when the shaft 7 rotates, the lubricating oil present on the inner periphery of the third lip 13 is pushed by the air flowing in the circumferential direction and returned to the sealing fluid side along the third protrusion. Note that a third groove may be provided instead of such a third protrusion.

The above embodiments are illustrative in all respects and are not restrictive. The scope of rights of the present invention is indicated by the claims rather than the embodiments described above, and includes all modifications within the scope of equivalents to the configurations described in the claims.

7 Shaft 7a Outer peripheral surface 8 Housing 10 Sealing device 11 First lip 12 Second lip 13 Third lip 14 Fixed part 16 First lip tip 17 Second lip tip 18 Third lip tip 19 Recess 21 First metal ring 22 Second metal ring 23 First covering portion 24 Second covering portion 28 Metal ring 29 Covering portion 38 First protrusion 39 Second protrusion 41 Side surface S Annular space

Claims (7)

A sealing device installed in an annular space formed between a shaft and a housing to prevent liquid on one axial side from leaking to the other axial side,
a fixing part fixed to the housing;
a first lip extending from the fixing part toward the shaft and having a first lip tip that contacts an outer circumferential surface of the shaft;
a second lip extending from the fixing part toward the axis and having a second lip tip located on the other side in the axial direction than the first lip tip;
a third lip extending from the fixing part toward the axis and having a third lip tip located on the other side in the axial direction than the second lip tip;
Equipped with
The third lip tip is not in contact with the outer peripheral surface of the shaft,
A recessed portion recessed radially outward is provided between the second lip and the third lip.
Sealing device. The sealing device according to claim 1, wherein the second lip has, on its inner periphery, a second protrusion or a second groove that guides the liquid to one side in the axial direction as the shaft rotates. The first lip has, on its inner periphery, a first protrusion or a first groove that guides the liquid to one side in the axial direction as the shaft rotates. Sealing device. the first lip tip contacts the outer circumferential surface of the shaft with a crushing margin;
The second lip tip contacts the outer circumferential surface of the shaft with a crushing margin, has a crushing margin of zero on the outer circumferential surface of the shaft, or does not contact the outer peripheral surface of the shaft. The sealing device according to claim 1 or claim 2. The fixing part includes a metal ring and a rubber covering part that covers at least an inner peripheral part of the metal ring,
The sealing device according to claim 1 or 2, wherein each of the second lip and the third lip extends from the common covering portion. The sealing device according to claim 5, wherein the third lip is located on one side in the axial direction rather than the other side surface in the axial direction of the covering portion. 6. The sealing device according to claim 5, wherein the second lip tip portion is located inside in the radial direction of a portion of the covering portion of the fixing portion to which the first lip is connected.

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