Sealing device and sealing structure

Abstract

To enable a plurality of sealing devices to be stacked easily and stably with sufficient sealing effect by the sealing devices maintained.SOLUTION: A sealing device 30 seals an annular gap between a housing 10 and a shaft body 20. The sealing device 30 includes a first seal part 40 and a second seal part 50 arranged along an axial direction. The first seal part 40 includes: a first reinforcement ring 41; a first annular elastic body 42 installed at the first reinforcement ring 41, the first annular elastic body 42 including a first seal lip 421 having an inner peripheral surface formed with a tip part 427; and a first annular spring 43 which presses the first seal lip 421 against the shaft body 20. The second seal part 50 includes: a second reinforcement ring 51; a second elastic body 52 installed at the second reinforcement ring 51, the second elastic body 52 including a second seal lip 521 having an inner peripheral surface formed with a tip part 527; and a second annular spring 53 which presses the second seal lip 521 against the shaft body 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a sealing device and a sealing structure. [Background technology]

[0002] Sealing devices that seal an annular gap between a shaft such as a rotating shaft and a housing into which the shaft is inserted have been proposed. For example, Patent Document 1 discloses a sealing device that includes a metal ring, an elastic body, and a garter spring. The elastic body includes a main lip and a dust lip that contact the shaft member, and a side lip that contacts a mating member fixed to the outer peripheral surface of the shaft member. The side lip extends elongatedly in the axial direction from the metal ring. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2020-8096 Summary of the Invention [Problem to be solved by the invention]

[0004] In the configuration of Patent Document 1, the side lip protrudes locally and elongatedly from the reinforcing ring. Therefore, for example, when storing or transporting multiple sealing devices, it is difficult to stably stack multiple sealing devices without a dedicated jig that accommodates the side lip. On the other hand, in a configuration that omits the side lip, it is difficult to maintain a sufficient sealing effect. In consideration of the above circumstances, one aspect of the present disclosure aims to enable multiple sealing devices to be easily and stably stacked while sufficiently maintaining the sealing effect of the sealing devices. [Means for solving the problem]

[0005] In order to solve the above problems, a sealing device according to one embodiment of the present disclosure is a sealing device that seals an annular gap between a housing and a shaft body, and includes a first seal portion and a second seal portion arranged along the axial direction, wherein the first seal portion includes a first reinforcing ring, a first elastomer installed on the first reinforcing ring, the first elastomer being an annular first elastomer having a first seal lip with a tip portion formed on the inner circumferential surface, and a first annular spring that presses the first seal lip against the shaft body, and the second seal portion includes a second reinforcing ring, a second elastomer installed on the second reinforcing ring, the second elastomer being an annular second elastomer having a second seal lip with a tip portion formed on the inner circumferential surface, and a second annular spring that presses the second seal lip against the shaft body.

[0006] A sealing structure according to one embodiment of the present disclosure is a sealing structure comprising a housing having an axial hole, a shaft inserted into the axial hole, and a sealing device that seals an annular gap between the housing and the shaft, wherein the sealing device comprises a first seal portion and a second seal portion arranged along the axial direction, the first seal portion comprising a first reinforcing ring, a first elastomer disposed on the first reinforcing ring, the first elastomer being an annular first elastomer having a first seal lip with a tip formed on its inner circumferential surface, and a first annular spring that presses the first seal lip against the shaft, and the second seal portion comprises a second reinforcing ring, a second elastomer disposed on the second reinforcing ring, the second elastomer being an annular second elastomer having a second seal lip with a tip formed on its inner circumferential surface, and a second annular spring that presses the second seal lip against the shaft. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view of the sealing structure according to the first embodiment. [Figure 2] FIG. 10 is an explanatory diagram of a state in which a plurality of sealing devices are stacked. [Figure 3] FIG. 6 is a cross-sectional view of a sealing structure according to a second embodiment. [Figure 4] FIG. 11 is an enlarged cross-sectional view of the vicinity of a first seal lip in a third embodiment. [Figure 5]FIG. 10 is an explanatory diagram of a configuration for generating a transfer action in the third embodiment. [Figure 6] FIG. 10 is a cross-sectional view of a sealing structure according to a modified example. [Figure 7] FIG. 10 is a cross-sectional view of a sealing structure according to a modified example. [Figure 8] FIG. 10 is a cross-sectional view of a sealing structure according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0008] The embodiments for carrying out the present disclosure will be described with reference to the drawings. Note that the dimensions and scale of each element in each drawing may differ from those of the actual product. Furthermore, the embodiment described below is an exemplary embodiment that may be envisioned when carrying out the present disclosure. Therefore, the scope of the present disclosure is not limited to the embodiment exemplified below.

[0009] A: First embodiment 1 is a cross-sectional view of a sealing structure 100 according to a first embodiment of the present disclosure. The sealing structure 100 according to the first embodiment is used in various mechanisms (e.g., differential side) mounted on a moving body such as an automobile. However, the use of the sealing structure 100 is arbitrary and is not limited to the above examples.

[0010] As illustrated in FIG. 1 , the sealing structure 100 includes a housing 10, a shaft 20, and a sealing device 30. The housing 10 is a hollow structure in which a shaft hole 11 is formed. The shaft hole 11 is an opening with a circular cross section. The shaft 20 is a cylindrical shaft that is inserted into the shaft hole 11. The shaft 20 rotates or reciprocates within the shaft hole 11. An annular gap δ is formed between the inner circumferential surface of the shaft hole 11 in the housing 10 and the outer circumferential surface of the shaft 20. The sealing device 30 is an annular structure that seals the gap δ.

[0011] 1 illustrates a central axis Z of the sealing device 30. In the following description, one direction along the central axis Z is referred to as the Z1 direction, and the direction opposite to the Z1 direction is referred to as the Z2 direction. Furthermore, the direction of the circumference of an imaginary circle of any diameter centered on the central axis Z is referred to as the "circumferential direction," and the direction of the radius of the imaginary circle is referred to as the "radial direction." In the radial direction, the direction toward the central axis Z is referred to as the "inner side," and the direction opposite the central axis Z is referred to as the "outer side."

[0012] The gap δ between the housing 10 and the shaft body 20 is divided into an external space S1 and an internal space S2 by the sealing device 30. The external space S1 is a space located in the Z1 direction of the sealing device 30. Specifically, the external space S1 is a space outside the housing 10, and is, for example, a space open to the atmosphere. The external space S1 contains, for example, muddy water. On the other hand, the internal space S2 is a space located in the Z2 direction of the sealing device 30. Specifically, the internal space S2 is a space inside the housing 10. The internal space S2 contains, for example, lubricating oil. The sealing device 30 is a structure for preventing leakage of lubricating oil from the internal space S2 to the external space S1 and intrusion of muddy water from the external space S1 into the internal space S2.

[0013] The sealing device 30 includes a first seal portion 40 and a second seal portion 50. The first seal portion 40 and the second seal portion 50 are annular structures disposed in the gap δ between the housing 10 and the shaft body 20 and surrounding the shaft body 20. The first seal portion 40 and the second seal portion 50 are stacked in the direction of the central axis Z. Specifically, the first seal portion 40 is positioned in the Z1 direction of the second seal portion 50. That is, the first seal portion 40 is positioned between the second seal portion 50 and the external space S1, and the second seal portion 50 is positioned between the first seal portion 40 and the internal space S2. The first seal portion 40 and the second seal portion 50 are fixed to each other with their central axes aligned (i.e., concentric).

[0014] The first seal portion 40 includes a first reinforcing ring 41, a first elastic body 42, and a first spring 43. The first reinforcing ring 41 and the first elastic body 42 are integrally formed by, for example, insert molding. Similarly, the second seal portion 50 includes a second reinforcing ring 51, a second elastic body 52, and a second spring 53. The first reinforcing ring 41 and the first elastic body 42 are integrally formed by, for example, insert molding. As described above, the sealing device 30 includes the first reinforcing ring 41 and the second reinforcing ring 51, which are separate bodies, and the first elastic body 42 and the second elastic body 52, which are separate bodies.

[0015] The first elastic body 42 and the second elastic body 52 are annular structures that are elastically deformable. The first elastic body 42 and the second elastic body 52 are formed of an elastic material such as a rubber material. Examples of rubber materials that can be used for the first elastic body 42 and the second elastic body 52 include various rubber materials such as chloroprene rubber (CR), silicone rubber (SR), acrylic rubber (ACM), urethane rubber (U), polyurethane rubber (PUR), vinyl methyl silicone rubber (VMQ), ethylene propylene diene rubber (EPDM), and fluororubber (FKM). The materials of the first elastic body 42 and the second elastic body 52 may be the same or different.

[0016] The first reinforcing ring 41 is an annular structure having higher rigidity than the first elastomer 42 and reinforces the mechanical strength of the first seal portion 40. Similarly, the second reinforcing ring 51 is an annular structure having higher rigidity than the second elastomer 52 and reinforces the mechanical strength of the second seal portion 50. The first reinforcing ring 41 and the second reinforcing ring 51 are formed, for example, from a metal material. Examples of metal materials used for the first reinforcing ring 41 and the second reinforcing ring 51 include stainless steel, SPCC (Steel Plate Cold Commercial), and SPHC (Steel Plate Hot Commercial). The first reinforcing ring 41 and the second reinforcing ring 51 may be formed, for example, from a high-rigidity resin material. The materials of the first reinforcing ring 41 and the second reinforcing ring 51 may be the same or different.

[0017] [First seal portion 40] The first reinforcing ring 41 of the first seal portion 40 includes a first tubular portion 411 and a first annular portion 412. The first tubular portion 411 is a cylindrical portion centered on the central axis Z. The first annular portion 412 is an annular portion that protrudes radially inward from the inner circumferential surface of the first tubular portion 411. Specifically, the first annular portion 412 protrudes inward from the end of the first tubular portion 411 in the Z1 direction. In other words, the first reinforcing ring 41 is formed to have an L-shaped cross section.

[0018] The first elastic body 42 is installed in the first reinforcing ring 41. The first elastic body 42 is an elastic member including a first seal lip 421, an auxiliary lip 422, a first covering portion 423, and a first connecting portion 424. The first seal lip 421, the auxiliary lip 422, the first covering portion 423, and the first connecting portion 424 are integrally formed.

[0019] The first seal lip 421 is an annular protrusion that contacts the outer peripheral surface of the shaft body 20. The inner peripheral surface of the first seal lip 421 that faces the shaft body 20 includes inclined surfaces 425 and 426 that intersect with each other. The inclined surface 425 is a conical surface that is inclined with respect to the central axis Z so that the distance between the end portion in the Z1 direction and the central axis Z is greater than the distance between the end portion in the Z2 direction and the central axis Z. On the other hand, the inclined surface 426 is a conical surface that is inclined with respect to the central axis Z so that the distance between the end portion in the Z1 direction and the central axis Z is less than the distance between the end portion in the Z2 direction and the central axis Z. Therefore, the inclined surfaces 425 and 426 form an angular cross-sectional shape.

[0020] The portion of the first seal lip 421 where the inclined surface 425 and the inclined surface 426 intersect is the tip end 427 of the first seal lip 421. In other words, the annular tip end 427 is formed on the inner circumferential surface of the first seal lip 421. The tip end 427 of the first seal lip 421 comes into contact with the outer circumferential surface of the shaft body 20.

[0021] The auxiliary lip 422 is an annular protrusion located in the Z1 direction of the first seal lip 421. The auxiliary lip 422 is located between the first seal lip 421 and the external space S1. That is, the first seal lip 421 is located between the auxiliary lip 422 and the second seal portion 50. The auxiliary lip 422 extends from the base end of the first seal lip 421 toward the shaft body 20. The tip end of the auxiliary lip 422 contacts the outer peripheral surface of the shaft body 20. With the above configuration, it is possible to reduce the possibility of muddy water entering the internal space S2 from the external space S1.

[0022] The first covering portion 423 is a cylindrical portion that covers the outer peripheral surface of the first cylindrical portion 411 of the first reinforcing ring 41. That is, the first covering portion 423 is located between the outer peripheral surface of the first cylindrical portion 411 and the inner peripheral surface of the axial hole 11. The outer peripheral surface of the first covering portion 423 contacts the inner peripheral surface of the axial hole 11. As described above, in the first embodiment, the first covering portion 423 of the first elastic body 42 that covers the outer peripheral surface of the first cylindrical portion 411 is in close contact with the inner peripheral surface of the housing 10, thereby effectively sealing the gap between the inner peripheral surface of the housing 10 and the sealing device 30.

[0023] The first connecting portion 424 is a portion that connects the first seal lip 421, the auxiliary lip 422, and the first covering portion 423. Specifically, the first connecting portion 424 is continuous across the outer circumferential surface of the first cylindrical portion 411 and the surface (specifically, the lower surface) of the first annular portion 412 that faces the Z1 direction.

[0024] The first spring 43 is an annular elastic body that presses the first seal lip 421 against the shaft body 20. Specifically, the first spring 43 is a coil spring (i.e., a garter spring) formed in an annular shape that surrounds the first seal lip 421. The first spring 43 presses the outer peripheral surface of the first seal lip 421 radially inward over the entire circumference. As a result of the tightening by the first spring 43, an appropriate contact pressure is ensured between the first seal lip 421 (tip end portion 427) and the shaft body 20.

[0025] [Second seal portion 50] The second reinforcing ring 51 of the second seal portion 50 includes a second tubular portion 511 and a second annular portion 512. The second tubular portion 511 is a cylindrical portion centered on the central axis Z. The second annular portion 512 is an annular portion that protrudes radially inward from the inner circumferential surface of the second tubular portion 511. Specifically, the second annular portion 512 protrudes inward from the end of the second tubular portion 511 in the Z1 direction. In other words, the second reinforcing ring 51 is formed to have an L-shaped cross section.

[0026] The dimension of the first cylindrical portion 411 in the direction of the central axis Z is greater than the dimension of the second cylindrical portion 511 in the direction of the central axis Z. In the above configuration, the first cylindrical portion 411 surrounds the second cylindrical portion 511. In other words, the first cylindrical portion 411 and the second cylindrical portion 511 overlap each other in the radial direction.

[0027] The second elastic body 52 is installed in the second reinforcing ring 51. The second elastic body 52 is an elastic member including a second seal lip 521, a second covering portion 522, and a second connecting portion 523. The second seal lip 521, the second covering portion 522, and the second connecting portion 523 are integrally formed.

[0028] The second seal lip 521 is an annular protrusion that contacts the outer peripheral surface of the shaft body 20. The inner peripheral surface of the second seal lip 521 that faces the shaft body 20 includes inclined surfaces 525 and 526 that intersect with each other. The inclined surface 525 is a conical surface that is inclined with respect to the central axis Z so that the distance between the end portion in the Z1 direction and the central axis Z is greater than the distance between the end portion in the Z2 direction and the central axis Z. On the other hand, the inclined surface 526 is a conical surface that is inclined with respect to the central axis Z so that the distance between the end portion in the Z1 direction and the central axis Z is less than the distance between the end portion in the Z2 direction and the central axis Z. Therefore, the inclined surfaces 525 and 526 form an angular cross-sectional shape.

[0029] The portion of the second seal lip 521 where the inclined surface 525 and the inclined surface 526 intersect is the tip end 527 of the second seal lip 521. In other words, an annular tip end 527 is formed on the inner circumferential surface of the first seal lip 421. The tip end 527 of the second seal lip 521 contacts the outer circumferential surface of the shaft 20 in the Z2 direction of the tip end 427 of the first seal lip 421.

[0030] A transfer mechanism 528 is formed on the inclined surface 525 of the second seal lip 521. The transfer mechanism 528 is a mechanism for transferring lubricating oil leaked from the internal space S2 in the Z1 direction of the second seal lip 521 to the internal space S2. Specifically, the transfer mechanism 528 is composed of a plurality of protrusions 529. The plurality of protrusions 529 exert a pumping action to transfer lubricating oil leaked from the internal space S2 in the Z1 direction of the second seal lip 521 to the internal space S2 by utilizing the relative rotation between the housing 10 and the shaft body 20. The shape of each protrusion 529 is arbitrary. For example, a protrusion with a triangular cross section or a spiral rib is used as the protrusion 529. As can be seen from FIG. 1 , the second seal lip 521 (inclined surface 525) has a plurality of protrusions 529 formed thereon, whereas the first seal lip 421 does not have a plurality of protrusions 529 formed thereon.

[0031] The Z1 direction mentioned above can also be expressed as the direction from the second seal lip 521 to the first seal lip 421. Similarly, the Z2 direction can also be expressed as the direction from the first seal lip 421 to the second seal lip 521.

[0032] The second connecting portion 523 is a portion that connects the second seal lip 521 and the second covering portion 522. Specifically, the second connecting portion 523 covers the surface (specifically, the lower surface) of the second annular portion 512 that faces the Z1 direction.

[0033] The second covering portion 522 is a cylindrical portion that covers the outer peripheral surface of the second cylindrical portion 511 of the second reinforcing ring 51. That is, the second covering portion 522 is located between the outer peripheral surface of the second cylindrical portion 511 and the inner peripheral surface of the axial hole 11. As described above, the first cylindrical portion 411 surrounds the second cylindrical portion 511. In the above configuration, the outer peripheral surface of the second covering portion 522 contacts the inner peripheral surface of the first cylindrical portion 411. Specifically, the second covering portion 522 contacts the inner peripheral surface of the first cylindrical portion 411 in a state where it is compressed radially over its entire circumference. That is, the outer peripheral surface of the second covering portion 522 contacts the inner peripheral surface of the first cylindrical portion 411 with an appropriate contact pressure.

[0034] As described above, the first seal portion 40 and the second seal portion 50 are fixed to each other by a configuration in which the first cylindrical portion 411 of the first seal portion 40 surrounds the second cylindrical portion 511 of the second seal portion 50. Specifically, the first seal portion 40 and the second seal portion 50 are fixed to each other by inserting the second seal portion 50 into the first cylindrical portion 411 of the first seal portion 40. As described above, according to the first embodiment, the first seal portion 40 and the second seal portion 50 can be fixed to each other by a simple configuration in which the second cylindrical portion 511 of the second reinforcing ring 51 is fitted into the first cylindrical portion 411 of the first reinforcing ring 41.

[0035] The second spring 53 is an annular elastic body that presses the second seal lip 521 against the shaft 20. Specifically, the second spring 53 is a coil spring (i.e., a garter spring) formed in an annular shape that surrounds the second seal lip 521. The second spring 53 presses the outer peripheral surface of the second seal lip 521 radially inward over the entire circumference. As a result of the tightening by the second spring 53, an appropriate contact pressure is ensured between the second seal lip 521 (tip end portion 527) and the shaft 20.

[0036] The space Q shown in FIG. 1 is the space between the first annular portion 412 of the first seal portion 40 and the second seal portion 50. Specifically, the space Q is a sealed space surrounded by the first cylindrical portion 411, the first annular portion 412, the first seal lip 421, and the second annular portion 512 of the second seal portion 50. The first spring 43 is located within the space Q. That is, the first annular portion 412 is located between the external space S1 and the first spring 43. Therefore, muddy water flowing from the external space S1 in the Z2 direction is blocked by the first annular portion 412. That is, the possibility that muddy water flowing from the external space S1 in the Z2 direction will adhere to the first spring 43 can be reduced. Therefore, deterioration of the first spring 43 due to, for example, adhesion of muddy water can be suppressed.

[0037] As described above, in the first embodiment, the first sealing action due to contact of the first seal lip 421 with the outer peripheral surface of the shaft body 20 and the second sealing action due to contact of the second seal lip 521 with the outer peripheral surface of the shaft body 20 are established in parallel. Therefore, it is possible to effectively seal the annular gap δ between the housing 10 and the shaft body 20 without requiring a portion that locally and elongates and protrudes from the reinforcing ring, as in the side lip of Patent Document 1, for example.

[0038] In the first embodiment, since a localized and elongated protruding portion (the side lip in Patent Document 1) is not necessary, a plurality of sealing devices 30 can be stably stacked, for example, in storage or transportation, as illustrated in Fig. 2. As described above, according to the first embodiment, a plurality of sealing devices 30 can be stacked simply and stably while the sealing action of the sealing devices 30 is sufficiently maintained.

[0039] In the configuration of Patent Document 1, the mating member with which the elongated side lip comes into contact needs to be fixed to the shaft member. In the first embodiment, the first seal lip 421 and the second seal lip 521 come into contact with the outer peripheral surface of the shaft body 20, making the side lip of Patent Document 1 unnecessary. Therefore, there is no need to install the mating member of Patent Document 1 on the shaft body 20. In other words, the first embodiment has the advantage of being able to simplify the configuration of the shaft body 20 compared to Patent Document 1.

[0040] Furthermore, in the first embodiment, the second covering portion 522 of the second elastic body 52 is interposed between the first cylindrical portion 411 and the second cylindrical portion 511. Therefore, compared to a configuration in which the inner circumferential surface of the first cylindrical portion 411 and the outer circumferential surface of the second cylindrical portion 511 are in direct contact with each other (for example, the configuration illustrated in FIG. 6), the gap between the first seal portion 40 and the second seal portion 50 can be sealed more effectively.

[0041] B: Second embodiment A second embodiment will be described. In the following embodiments, elements that have the same functions as those in the first embodiment will be denoted by the same reference numerals as those in the first embodiment, and detailed descriptions thereof will be omitted as appropriate.

[0042] 3 is a cross-sectional view of a sealing structure 100 according to the second embodiment. In the sealing structure 100 of the second embodiment, the configurations of the first seal portion 40 and the second seal portion 50 are different from those of the first embodiment.

[0043] In the second embodiment, the first elastomer 42 of the first seal portion 40 includes a first seal lip 421 and an auxiliary lip 422. The first covering portion 423 and the first connecting portion 424 illustrated in the first embodiment are omitted in the first embodiment. Therefore, the outer peripheral surface of the first cylindrical portion 411 of the first reinforcing ring 41 is exposed from the first elastomer 42.

[0044] The second reinforcing ring 51 of the second seal portion 50 includes a second tubular portion 511 and a second annular portion 512. The second tubular portion 511 is a cylindrical portion centered on the central axis Z. The second annular portion 512 is an annular portion extending from the base end of the second seal lip 521 toward the end of the second tubular portion 511 in the Z2 direction. Specifically, the second annular portion 512 includes a portion that is inclined with respect to the central axis Z so as to increase in diameter from the end in the Z1 direction (near the base end of the second seal lip 521) toward the end in the Z2 direction (the end in the Z2 direction of the second tubular portion 511).

[0045] In the second embodiment, the dimension of the second cylindrical portion 511 in the direction of the central axis Z is greater than the dimension of the first cylindrical portion 411 in the direction of the central axis Z. In the above configuration, the second cylindrical portion 511 surrounds the first cylindrical portion 411. In other words, the first cylindrical portion 411 and the second cylindrical portion 511 overlap each other in the radial direction.

[0046] Furthermore, the second elastic body 52 of the second seal portion 50 includes a second seal lip 521, a second covering portion 522, and a second connecting portion 523. The shape of the second seal lip 521 is the same as in the first embodiment. The second connecting portion 523 is a portion that connects the second seal lip 521 and the second covering portion 522. Specifically, the second connecting portion 523 covers the surface (specifically, the upper surface) of the second annular portion 512 that faces the Z2 direction.

[0047] The second covering portion 522 is a cylindrical portion that covers the outer peripheral surface of the second cylindrical portion 511 of the second reinforcing ring 51. That is, the second covering portion 522 is located between the outer peripheral surface of the second cylindrical portion 511 and the inner peripheral surface of the axial hole 11. The outer peripheral surface of the second covering portion 522 contacts the inner peripheral surface of the axial hole 11. As described above, in the second embodiment, the second covering portion 522 of the second elastic body 52 that covers the outer peripheral surface of the second cylindrical portion 511 is in close contact with the inner peripheral surface of the housing 10, thereby effectively sealing the gap between the inner peripheral surface of the housing 10 and the sealing device 30.

[0048] In the above configuration, the outer peripheral surface of the first cylindrical portion 411 and the inner peripheral surface of the second cylindrical portion 511 are in contact with each other. That is, the first cylindrical portion 411 made of a metal material is fitted (i.e., metal fitting) into the second cylindrical portion 511 made of a metal material.

[0049] As described above, the first seal portion 40 and the second seal portion 50 are fixed to each other by a configuration in which the second cylindrical portion 511 of the second seal portion 50 surrounds the first cylindrical portion 411 of the first seal portion 40. Specifically, the first seal portion 40 and the second seal portion 50 are fixed to each other by inserting the first seal portion 40 into the first cylindrical portion 411 of the second seal portion 50. As described above, according to the second embodiment, the first seal portion 40 and the second seal portion 50 can be fixed to each other by a simple configuration in which the first cylindrical portion 411 of the first reinforcing ring 41 is fitted into the second cylindrical portion 511 of the second reinforcing ring 51.

[0050] As explained above, in the second embodiment, as in the first embodiment, a first sealing action due to contact of the first seal lip 421 with the outer peripheral surface of the shaft body 20 and a second sealing action due to contact of the second seal lip 521 with the outer peripheral surface of the shaft body 20 are established in parallel. Therefore, the annular gap δ between the housing 10 and the shaft body 20 can be effectively sealed without requiring a portion that locally and elongates and protrudes from the reinforcing ring, as in the side lip of Patent Document 1, for example.

[0051] Furthermore, in the second embodiment, since a locally and elongated protruding portion (the side lip in Patent Document 1) is not necessary, a plurality of sealing devices 30 can be stably stacked, for example, in storage or transportation, as illustrated in Fig. 2. As described above, according to the second embodiment, similar to the first embodiment, a plurality of sealing devices 30 can be stacked simply and stably while the sealing action of the sealing devices 30 is sufficiently maintained.

[0052] C: Third embodiment The third embodiment relates to the shape of the first seal lip 421. The third embodiment is applicable to the first seal lip 421 of both the first and second embodiments.

[0053] Fig. 4 is an enlarged cross-sectional view of the vicinity of the tip end 427 of the first seal lip 421 in the third embodiment. Fig. 4 shows the center C of the cross section of the first spring 43 (hereinafter referred to as the "cross-sectional center"). Angle θ1 in Fig. 4 is the angle between the inclined surface 425 of the first seal lip 421 and the direction of the central axis Z. Angle θ1 can also be expressed as the angle between the inclined surface 425 and the outer peripheral surface of the shaft 20. Angle θ2 in Fig. 4 is the angle between the inclined surface 426 of the first seal lip 421 and the direction of the central axis Z. Angle θ2 can also be expressed as the angle between the inclined surface 426 and the outer peripheral surface of the shaft 20.

[0054] In the third embodiment, the position of the tip 427 of the first seal lip 421 in the direction of the central axis Z, the position of the cross-sectional center C of the first spring 43 in the direction of the central axis Z, and the angles θ1 and θ2 of the first seal lip 421 are selected so as to generate an action of moving liquid present near the tip 427 of the first seal lip 421 in the Z1 direction (hereinafter referred to as the "transfer action").

[0055] Fig. 5 is an explanatory diagram of a configuration that generates a transfer action. The contact range R shown in Fig. 5 is the range in the direction of the central axis Z where the first seal lip 421 contacts the outer peripheral surface of the shaft body 20. That is, the contact range R is defined as a result of the tip end 427 of the first seal lip 421 being deformed by pressure from the outer peripheral surface of the shaft body 20. Fig. 5 also shows the center Rc of the contact range R. Fig. 5 also shows the pressure distribution D of the first seal lip 421 within the contact range R and the peak P of the pressure distribution D. The pressure distribution D is the distribution of the contact pressure of the first seal lip 421 with the outer peripheral surface of the shaft body 20.

[0056] 5, the peak P of the pressure distribution D within the contact range R is located in the Z1 direction relative to the center Rc of the contact range R (hereinafter referred to as the "transfer condition"). In other words, the peak P of the pressure distribution D is located between the center Rc of the contact range R and the external space S1. As a result of the transfer condition being met, a transfer action is achieved that moves the liquid (e.g., muddy water) present near the tip 427 in the Z1 direction.

[0057] In the third embodiment, the shape of the first seal lip 421 and the position of the cross-sectional center C of the first spring 43 are selected so that the transfer conditions described above are met. For example, in the direction of the central axis Z, the tip end 427 of the first seal lip 421 and the cross-sectional center C of the first spring 43 are at different positions. Specifically, in the direction of the central axis Z, the tip end 427 is located in the Z1 direction from the cross-sectional center C. Furthermore, the angle θ1 of the inclined surface 425 of the first seal lip 421 is greater than the angle θ2 of the inclined surface 426 (θ1 > θ2). As a result of the above-mentioned exemplary conditions being satisfied, the transfer conditions described above are met.

[0058] The third embodiment also achieves the same effects as the first or second embodiment. Furthermore, according to the third embodiment, the peak P of the pressure distribution D within the contact range R is located in the Z1 direction relative to the center Rc of the contact range R, so a transfer action occurs in which the liquid near the tip end 427 of the first seal lip 421 moves toward Z1. This reduces the possibility that muddy water that has reached the first seal portion 40 from the external space S1 will infiltrate the second seal portion 50.

[0059] In the configuration in which the transfer condition is satisfied for the first seal lip 421 of the second embodiment, the air in the space Q between the first seal portion 40 and the second seal portion 50 is transferred to the external space S1 by the transfer action of the first seal lip 421. Therefore, there is a possibility that the space Q becomes negative pressure. If the space Q is maintained at an excessively negative pressure, there is a possibility that leakage of lubricating oil from the internal space S2 to the space Q will be promoted.

[0060] In the second embodiment, the first seal portion 40 and the second seal portion 50 are fixed together by a metal fitting in which the first metallic cylindrical portion 411 and the second metallic cylindrical portion 511 are in direct contact with each other. In the above configuration, a small gap is formed between the first cylindrical portion 411 and the second cylindrical portion 511 due to minute irregularities formed on the outer peripheral surface of the first cylindrical portion 411 and the inner peripheral surface of the second cylindrical portion 511. That is, the space Q communicates with the external space S1 through the small gap between the outer peripheral surface of the first cylindrical portion 411 and the inner peripheral surface of the second cylindrical portion 511. This reduces the possibility that the space Q will be maintained at an excessively negative pressure.

[0061] D: Modification Specific modified embodiments that can be added to the embodiments exemplified above are shown below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not being mutually contradictory.

[0062] (1) In the above-described embodiments, the first elastic body 42 includes the auxiliary lip 422, but the auxiliary lip 422 may be omitted. Similarly, the first connecting portion 424 may be omitted from the first elastic body 42. Furthermore, the first elastic body 42 may be composed of a plurality of portions spaced apart from one another. Similarly, the second connecting portion 523 may be omitted from the second elastic body 52. ​​Furthermore, the second elastic body 52 may be composed of a plurality of portions spaced apart from one another.

[0063] (2) In the first embodiment, the second covering portion 522 covers the outer peripheral surface of the second cylindrical portion 511. However, as illustrated in Fig. 6, the second covering portion 522 may be omitted from the second elastic body 52. ​​That is, in the first embodiment, the inner peripheral surface of the first cylindrical portion 411 and the outer peripheral surface of the second cylindrical portion 511 may be in direct contact with each other. Specifically, the first cylindrical portion 411 made of a metal material is fitted (i.e., metal fitting) into the second cylindrical portion 511 made of a metal material.

[0064] (3) In the second embodiment, the outer circumferential surface of the first cylindrical portion 411 and the inner circumferential surface of the second cylindrical portion 511 are in contact with each other. However, as illustrated in FIG. 7 , the first covering portion 423 of the first elastic body 42 may be interposed between the first cylindrical portion 411 and the second cylindrical portion 511. The first covering portion 423 in FIG. 7 covers the outer circumferential surface of the first cylindrical portion 411. The outer circumferential surface of the first covering portion 423 is in contact with the inner circumferential surface of the second cylindrical portion 511.

[0065] (4) In each of the above-described embodiments, the second seal portion 50 may include an auxiliary lip 524. For example, FIG. 8 illustrates an embodiment in which an auxiliary lip 524 is added to the second elastic body 52 in the first embodiment. The annular auxiliary lip 524 is provided in the Z1 direction of the second seal lip 521. That is, the auxiliary lip 524 is located between the second seal lip 521 and the first seal portion 40.

[0066] (5) In each of the above embodiments, the following configurations are exemplified. Configuration 1: Configuration in which the sealing device 30 includes a first seal portion 40 and a second seal portion 50 Configuration 2: A configuration in which the peak P of the pressure distribution D is located in the Z1 direction from the center Rc of the contact area R Configuration 1 and Configuration 2 are established independently of each other. That is, one of Configuration 1 and Configuration 2 is not essential for the other. For example, in a configuration in which the sealing device 30 is configured with only one of the first seal portion 40 and the second seal portion 50, Configuration 2 may be adopted for the seal lip of the sealing device 30 (for example, the first seal lip 421 of the first seal portion 40 or the second seal lip 521 of the second seal portion 50).

[0067] (6) The term "nth" (n is a natural number) in this application is used only as a formal and convenient label to distinguish each element in the description and does not have any substantive meaning. Therefore, there is no room for restrictive interpretation of the position of each element or the order of manufacture, etc., based on the term "nth."

[0068] E: Notes From the above-described exemplary embodiments, the following configurations can be understood, for example.

[0069] A sealing device according to one aspect (aspect 1) of the present disclosure is a sealing device that seals an annular gap between a housing and a shaft body, and includes a first seal portion and a second seal portion arranged along the axial direction, wherein the first seal portion includes a first reinforcing ring, a first elastomer installed on the first reinforcing ring, the first elastomer being an annular first elastomer having a first seal lip with a tip portion formed on the inner circumferential surface, and a first annular spring that presses the first seal lip against the shaft body, and the second seal portion includes a second reinforcing ring, a second elastomer installed on the second reinforcing ring, the second elastomer being an annular second elastomer having a second seal lip with a tip portion formed on the inner circumferential surface, and a second annular spring 53 that presses the second seal lip against the shaft body.

[0070] In the above-described embodiment, the first sealing action due to contact of the first seal lip with the outer peripheral surface of the shaft and the second sealing action due to contact of the second seal lip with the outer peripheral surface of the shaft are established in parallel. Therefore, the annular gap between the shaft and the housing can be effectively sealed without requiring a localized, elongated protrusion, such as a side lip, extending axially from the reinforcing ring. Furthermore, because a localized, elongated protrusion is not required, multiple sealing devices can be stably stacked, for example, during storage or transportation.

[0071] In a specific example (Aspect 2) of Aspect 1, the first reinforcing ring includes a first cylindrical portion, and the second reinforcing ring includes a second cylindrical portion, and the first seal portion and the second seal portion are fixed to each other by a configuration in which one of the first cylindrical portion and the second cylindrical portion surrounds the other. In the above aspect, the first seal portion and the second seal portion can be fixed to each other by a simple configuration in which one of the first cylindrical portion of the first reinforcing ring and the second cylindrical portion of the second reinforcing ring is fitted with the other.

[0072] In a specific example (Aspect 3) of Aspect 2, the first reinforcing ring includes a first annular portion that protrudes inward from the inner circumferential surface of the first cylindrical portion, and the first spring is located in the space between the first annular portion and the second seal portion. In the above aspect, the first annular portion is located between the first spring and a first space that is located on the opposite side of the first seal portion from the second seal portion. Therefore, fluid (e.g., muddy water) flowing from the first space toward the sealing device is blocked by the first annular portion. In other words, the possibility of fluid flowing from the first space toward the sealing device adhering to the first spring can be reduced.

[0073] In a specific example (Aspect 4) of Aspect 3, the first elastic body includes a first covering portion that covers the outer peripheral surface of the first cylindrical portion, and the first cylindrical portion surrounds the second cylindrical portion. In the above aspect, the first covering portion of the first elastic body that covers the outer peripheral surface of the first cylindrical portion is in close contact with the inner peripheral surface of the housing, thereby effectively sealing the gap between the inner peripheral surface of the housing and the sealing device.

[0074] In a specific example (Aspect 5) of Aspect 4, the second elastic body includes a second covering portion that covers the outer peripheral surface of the second cylindrical portion, and the outer peripheral surface of the second covering portion contacts the inner peripheral surface of the first cylindrical portion. In the above aspect, the second covering portion of the second elastic body is interposed between the first cylindrical portion and the second cylindrical portion. Therefore, compared to, for example, an aspect in which the inner peripheral surface of the first cylindrical portion and the outer peripheral surface of the second cylindrical portion are in direct contact, the gap between the first seal portion and the second seal portion can be sealed more effectively.

[0075] In a specific example (Aspect 6) of Aspect 3, the second elastic body includes a second covering portion that covers the outer peripheral surface of the second cylindrical portion, and the second cylindrical portion surrounds the first cylindrical portion. In the above aspect, the second covering portion of the second elastic body that covers the outer peripheral surface of the second cylindrical portion is in close contact with the inner peripheral surface of the housing, thereby effectively sealing the gap between the inner peripheral surface of the housing and the sealing device.

[0076] In a specific example (Aspect 7) of Aspect 6, the first cylindrical portion and the second cylindrical portion are formed of a metal material, and the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion are in contact with each other. In this aspect, the space between the first annular portion and the second seal portion communicates with the first space through a small gap between the outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion. This reduces the possibility that the space will be maintained at a negative pressure.

[0077] In a specific example (Aspect 8) of any of Aspects 1 to 7, the first elastic body includes an auxiliary lip that contacts the outer peripheral surface of the shaft, and the first seal lip is located between the auxiliary lip and the second seal portion. In the above aspect, it is possible to reduce the possibility that liquid (e.g., muddy water) in the first space will infiltrate from a first space (e.g., an external space) located on the opposite side of the first seal portion from the second seal portion to a second space (e.g., the second space) located on the opposite side of the second seal portion from the first seal portion.

[0078] In a specific example (Aspect 9) of any of Aspects 1 to 8, the sealing device divides the gap between the housing and the shaft into a first space and a second space, and the peak of the pressure distribution within the contact area where the first seal lip contacts the outer circumferential surface of the shaft is located closer to the first space than the center of the contact area. In the above aspects, since the peak of the pressure distribution within the contact area is located closer to the first space than the center of the contact area, a transfer action occurs in which liquid near the tip of the first seal lip moves toward the first space. This reduces the possibility that liquid reaching the first seal portion from the first space will infiltrate the second seal portion.

[0079] A sealing structure according to one aspect (aspect 10) of the present disclosure is a sealing structure comprising a housing having an axial hole, a shaft inserted into the axial hole, and a sealing device that seals an annular gap between the housing and the shaft, wherein the sealing device comprises a first seal portion and a second seal portion arranged along the axial direction, the first seal portion comprising a first reinforcing ring, a first elastomer installed on the first reinforcing ring, the first elastomer being an annular first elastomer having a first seal lip with a tip portion formed on the inner circumferential surface, and a first annular spring that presses the first seal lip against the shaft, and the second seal portion comprises a second reinforcing ring, a second elastomer installed on the second reinforcing ring, the second elastomer being an annular second elastomer having a second seal lip with a tip portion formed on the inner circumferential surface, and a second annular spring that presses the second seal lip against the shaft.

[0080] In a configuration in which a sealing device divides the annular space between a housing and a shaft into a first space and a second space, when liquid (e.g., muddy water) is present in the first space, it is necessary to sufficiently prevent the liquid in the first space from passing through the gap between the sealing device and the shaft and reaching the second space. While ensuring sufficient contact pressure of the sealing device against the outer circumferential surface of the shaft can sufficiently prevent the liquid from entering the second space from the first space, problems such as an increase in the torque required to rotate the shaft or the tendency of the sealing device's portion in contact with the shaft to wear may be anticipated. In consideration of the above circumstances, one aspect of the present disclosure aims to prevent the liquid from entering the second space from the first space without excessively increasing the contact pressure of the sealing device against the shaft.

[0081] To solve the above problems, one aspect of the present disclosure provides a sealing device installed in an annular space between a housing and a shaft, dividing the space into a first space and a second space. The sealing device includes an annular elastic body including a seal lip, and the peak of the pressure distribution within the contact area where the seal lip contacts the outer circumferential surface of the shaft is located closer to the first space than the center of the contact area. In the above aspect, the peak of the pressure distribution within the contact area is located closer to the first space than the center of the contact area, causing a transfer action in which liquid near the tip of the first seal lip moves toward the first space. This reduces the possibility of liquid reaching the first seal portion from the first space infiltrating into the second seal portion. In other words, it is possible to prevent liquid from infiltrating from the first space to the second space without excessively increasing the contact pressure of the sealing device against the shaft. [Explanation of symbols]

[0082] 100...sealing structure, 10...housing, 11...shaft hole, 20...shaft body, 30...sealing device, 40...first seal portion, 41...first reinforcing ring, 411...first cylindrical portion, 412...first annular portion, 42...first elastomer, 421...first seal lip, 422...auxiliary lip, 423...first covering portion, 424...first connecting portion, 425...inclined surface, 426...inclined surface, 427...tip portion, 43...first spring, 50...second seal portion, 51...second reinforcing ring, 511...second cylindrical portion, 512...second annular portion, 52...second elastomer, 521...second seal lip, 522...second covering portion 2, 523...second connecting portion, 525...inclined surface, 526...inclined surface, 527...tip portion, 528...transfer mechanism, 529...protrusion.

Claims

1. A sealing device that seals an annular gap between a housing and a shaft body, a first seal portion and a second seal portion arranged along an axial direction; The first seal portion is A first reinforcing ring; a first elastic body disposed on the first reinforcing ring, the first elastic body being annular and including a first seal lip having a tip end formed on an inner circumferential surface; an annular first spring that presses the first seal lip against the shaft; The second seal portion is A second reinforcing ring; a second elastic body disposed on the second reinforcing ring, the second elastic body being annular and including a second seal lip having a tip end portion formed on an inner peripheral surface; and a second annular spring that presses the second seal lip against the shaft. Sealing device.

2. the first reinforcing ring includes a first cylindrical portion, the second reinforcing ring includes a second cylindrical portion, The first seal portion and the second seal portion are fixed to each other by a configuration in which one of the first cylindrical portion and the second cylindrical portion surrounds the other. The sealing device of claim 1.

3. the first reinforcing ring includes a first annular portion protruding inward from an inner circumferential surface of the first cylindrical portion, The first spring is located in a space between the first annular portion and the second seal portion. The sealing device of claim 2.

4. the first elastic body includes a first covering portion that covers an outer peripheral surface of the first cylindrical portion, The first cylindrical portion surrounds the second cylindrical portion. The sealing device of claim 3.

5. the second elastic body includes a second covering portion that covers an outer peripheral surface of the second cylindrical portion, The outer circumferential surface of the second covering portion contacts the inner circumferential surface of the first cylindrical portion. The sealing device of claim 4.

6. the second elastic body includes a second covering portion that covers an outer peripheral surface of the second cylindrical portion, The second cylindrical portion surrounds the first cylindrical portion. The sealing device of claim 3.

7. the first cylindrical portion and the second cylindrical portion are formed of a metal material, The outer peripheral surface of the first cylindrical portion and the inner peripheral surface of the second cylindrical portion are in contact with each other. The sealing device of claim 6.

8. the first elastic body includes an auxiliary lip that contacts an outer circumferential surface of the shaft body, The first seal lip is located between the auxiliary lip and the second seal portion. The sealing device of claim 1.

9. the sealing device divides a gap between the housing and the shaft into a first space and a second space, The peak of the pressure distribution within the contact area where the first seal lip contacts the outer peripheral surface of the shaft is located closer to the first space than the center of the contact area. The sealing device of claim 1.

10. a housing in which an axial hole is provided; a shaft inserted into the shaft hole; a sealing device that seals an annular gap between the housing and the shaft; A sealing structure comprising: The sealing device is a first seal portion and a second seal portion arranged along an axial direction; The first seal portion is A first reinforcing ring; a first elastic body disposed on the first reinforcing ring, the first elastic body being annular and including a first seal lip having a tip end formed on an inner circumferential surface; an annular first spring that presses the first seal lip against the shaft; The second seal portion is A second reinforcing ring; a second elastic body disposed on the second reinforcing ring, the second elastic body being annular and including a second seal lip having a tip end portion formed on an inner peripheral surface; and a second annular spring that presses the second seal lip against the shaft. Sealed structure.

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