TWI843847B - Sealing structure - Google Patents

Abstract

A sealing structure (1) includes a first member (11) having a cylindrical portion, a second member (6) and an annular sealing member (7) configured to seal a space between the first member (11) and the second member (6), the space being supplied with a lubricant. The annular sealing member (7) includes: a fixing portion fixed to the first member (11); a rubber lip portion (31) having a base portion (31a) extending in a first axial direction from the fixing portion and a contacting portion (31c) configured to contact the sealing surface (41); a pressing member provided between the base portion (31a) and the contacting portion (31c) to press the contacting portion (31c) toward the sealing surface (41); and a supporting portion (45) provided along the base portion (31a) and having higher rigidity than the base portion (31a).

Description

Sealing structure

The present invention relates to a sealing structure disposed between two components that rotate relative to each other, such as a shaft portion and a bearing cup in a cross joint.

For example, in a main shaft device of a steel rolling machine or a drive shaft of an automobile, a cross joint is used as a universal joint at a connection portion between shafts. The cross joint has a cross shaft, a bearing cup, and a plurality of needle rollers. The cross shaft has four shaft portions arranged in a cross shape. The bearing cup has a bottomed cylindrical shape and covers each shaft portion. The needle roller is arranged between the outer peripheral surface of the shaft portion and the inner peripheral surface of the bearing cup so as to be able to roll relative to the shaft portion and the bearing cup. A shaft provided at the end of each shaft portion is connected to the bearing cup. A sealing structure is provided between the base end of the shaft portion and the end of the bearing cup. This inhibits water and the like from entering the roller accommodation space provided between the shaft portion and the bearing cup, and also inhibits the lubricant from leaking from the accommodation space to the outside (for example, see Japanese Unexamined Patent Application Announcement No. 2018-80828 (JP 2018-80828 A)).

The sealing structure disclosed in JP 2018-80828A includes an annular sealing member 107, which is attached to the bearing cup 111 and contacts the oil baffle 106 so as to be slidable relative to the oil baffle 106, as shown in FIG. 11. The oil baffle 106 has a sealing surface 141 with a radial surface facing inward. The sealing member 107 includes a metal member 134, a lip 131, and an annular spring 151. The metal member 134 is fixed to the bearing cup 111. The lip 131 is attached to the metal member 134 and contacts the sealing surface 141. The annular spring 151 presses the lip 131 toward the sealing surface 141.

When the space (lubricating space) between the oil baffle 106 and the bearing cup 111 is lubricated with lubricant (grease), an operation of replacing the lubricant in the lubricating space with new lubricant is performed during maintenance, etc. Therefore, it is necessary to supply new lubricant from the oil filling hole and discharge the old lubricant from the space between the lip 131 and the sealing surface 141 to the outside. However, in the case of the sealing structure shown in FIG. 11, when new lubricant is supplied to the lubricating space, the internal pressure of the lubricant causes a force that presses the lip 131 against the sealing surface 141, as shown in arrow c in FIG. 12. Then, substantially the entire side surface 131c2 of the lip 131 facing the sealing surface 141 strongly contacts the sealing surface 141. Therefore, it is difficult to discharge the lubricant to the outside of the lubrication space through the space between the lip 131 and the sealing surface 141.

The invention disclosed herein provides a sealing structure for sealing a space (lubricating space) supplied with lubricant, and when new lubricant is supplied, the sealing structure can improve the discharge performance of old lubricant.

The sealing structure according to the aspect of the present invention includes: a first member having a cylindrical portion; a second member having a main body, the main body being located radially inward of the cylindrical portion and being arranged concentrically with the first member so as to rotate relative to the first member; and an annular sealing member attached to the first member and configured to seal a space between the first member and the second member, and supplying the space with a lubricant. The second member further includes a first extension portion and a second extension portion, the first extension portion extending radially outwardly from a portion of the main body on a first axial side, and the second extension portion extending from a radially outer end of the first extension portion in a second axial direction and having a sealing surface facing radially inward. The annular sealing member includes: a fixing portion fixed to a first member; a rubber lip having a base portion, a contact portion, and a connecting portion, wherein the base portion extends from the fixing portion in a first axial direction, the contact portion is provided with a gap between the contact portion and the base portion radially outward of the base portion, and is constructed to form a contact sealing surface, and the connecting portion connects a portion of the base portion on the first axial side and a portion of the contact portion on the first axial side; a pressing member provided between the base portion and the contact portion to press the contact portion toward the sealing surface; and a supporting portion provided along the base portion and having a higher rigidity than the base portion.

In the sealing structure, a high-rigidity support portion is provided along the base of the rubber lip. Thus, it is possible to suppress the lip from strongly pressing the sealing surface due to the pressure of the lubricant supplied to the space between the first member and the second member. Therefore, the discharge performance of the old lubricant can be improved when the new lubricant is supplied.

In the above aspect, the fixing portion may have a metal member attached to the first member, and the supporting portion may be separated from the metal member. Even when one or both of the metal member and the supporting portion have/have a bent portion, the metal member and the supporting portion may be manufactured separately, which facilitates the manufacturing.

In the above embodiment, the support portion may have a cylindrical support body portion and an auxiliary portion, wherein the cylindrical support body portion extends along the base portion in the axial direction, and the auxiliary portion is formed integrally with the cylindrical support body portion and is constructed to contact a portion of the metal member in the axial direction. In this case, when the rubber lip, the support portion, and the sealing member including the metal member are molded for integration, the support portion axially contacts a portion of the metal member, thereby facilitating the support portion and the metal portion to be supported in the axial direction.

In the above embodiment, the metal member may have a cylindrical portion attached to the first member and an annular portion extending radially inward from the cylindrical portion. The auxiliary portion may extend radially inward from the second axial end of the cylindrical support body portion and have an annular shape. The radial inner end of the auxiliary portion may further protrude radially inward relative to the radial inner end of the annular portion. In this case, when the rubber lip, the support portion, and the sealing member including the metal member are integrally formed using a mold, a portion of the mold may be brought into contact with the radially inwardly protruding end of the auxiliary portion. This helps to position the support portion in the radial direction.

In the above aspect, the contact portion may have a facing surface facing the sealing surface; and the facing surface may have a full contact area and a partial contact area, the full contact area being provided in a portion of the facing surface on the second axial side corresponding to the outer side of the space and being constructed to contact the sealing surface on the entire circumference of the full contact area, and the partial contact area being provided in a portion of the facing surface on the first axial side corresponding to the space side and being constructed to contact the sealing surface discontinuously in the circumferential direction of the partial contact area. According to the above configuration, even when the lip is pressed against the sealing surface by the lubricant supplied to the space, there is a portion in the partial contact area of the facing surface that does not contact the sealing surface. Therefore, when the lubricant enters the portion, the lubricant pushes the complete contact area upward and is discharged to the outside of the space. Therefore, the discharge performance of the old lubricant can be further improved when the new lubricant is supplied. Furthermore, since the facing surface has a complete contact area, the sealing performance is ensured.

In the above embodiment, the pressing member may be an annular spring; and the boundary between the full contact area and the partial contact area may be in the axial range between the end of the annular spring located on the first axial side and the center of the annular spring. According to the above structure, when the boundary is located closer to the lubricating space side relative to the center of the annular spring, the surface pressure of the full contact area relative to the first sealing surface indicates a peak at the end of the full contact area outside the lubricating space. Therefore, water or the like can be properly inhibited from entering from the space outside the lubricating space, and the sealing performance can be properly maintained.

According to the sealing structure of the above aspect, in the sealing structure for sealing a space supplied with lubricant, it is possible to improve the discharge performance of the old lubricant when supplying new lubricant.

1: Sealing structure

2: Cross shaft

3: Base

3a: Oil filling hole

4: Shaft part

5: Rolling bearing part

6: Oil retaining ring

6a: Oil retaining ring body

6b: First extension part

6c: Second extension part

6d: The third extension

7: Sealing components

8: Roller guide

9: Rolling needle

10: Gasket

11: Bearing cup

11a: Oil filling hole

13: Oil filling path

14: Cylindrical part

15: Disc-shaped part

17:Yoke

20: Cross joint

31: Lips

31a: Base part

31b: Connection part

31c: Contact part

31c2: Surface facing

32: Lips

32a: Concave part

33: Lips

34:Metal components

34a: First metal component

34a1: first cylindrical part

34a2: First annular part

34b: Second metal component

34b1: Second cylindrical part

34b2: Second annular part

35: Cylindrical part

41: Sealing surface

42: Sealing surface

43: Sealing surface

45: Support part

46: Support the main body

46a: End

47: Auxiliary part

47a: Inner end

48a: Inner end

51: Ring spring

51a: Center

51b: End

52: Ring spring

61: Groove

61a: Deep groove part

61b: Shallow groove part

65: Partial

66: Partial

106: Oil retaining ring

107: Sealing component

111: Bearing cup

131: Lips

131c2: Side surface

134:Metal components

141: Sealing surface

151: Ring spring

R1: Full contact area

R2: Partial contact area

S: Accommodation space

The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which similar symbols indicate similar elements, and in which: [FIG. 1] is a partially exploded three-dimensional view of a cross joint applying a sealing structure; [FIG. 2] is a side view (partial cross-sectional view) of the cross joint; [FIG. 3] is a cross-sectional view of the sealing structure; [FIG. 4] is a cross-sectional view of a sealing member of the sealing structure; [FIG. 5] is a cross-sectional view showing the function of the first lip of the sealing member; [FIG. 6A] is a schematic view as viewed from arrow E in FIG. 5; [FIG. 6B] is a schematic view as viewed from arrow F in FIG. 5; [FIG. 7A] is a cross-sectional view showing the first lip with supply pressure without lubricant applied; [FIG. 7B] is a cross-sectional view showing the first lip with supply pressure applied ; [FIG. 8A] is an explanatory diagram showing changes in surface pressure in a full contact area relative to the first sealing surface of the sealing structure; [FIG. 8B] is an explanatory diagram showing changes in surface pressure in a full contact area relative to the first sealing surface of the sealing structure; [FIG. 9A] is a schematic diagram corresponding to FIG. 6A, and shows a modification of the groove of the first lip; [FIG. 9B] is a schematic diagram corresponding to FIG. 6B, and shows a modification of the groove of the first lip; [FIG. 10] is an explanatory diagram showing a state where the support portion is fixed to the mold; [FIG. 11] is a sectional diagram of a sealing structure according to the related art; and [FIG. 12] is a sectional diagram of a sealing structure according to the related art, which shows a lip applying a supply pressure of a lubricant.

Sealing structure and cross joints

FIG. 1 is a partially exploded perspective view of a cross joint to which a sealing structure is applied, and FIG. 2 is a side view (partial cross-sectional view) of the cross joint. For example, a cross joint 20 is used in a main shaft device (not shown) of a steel rolling mill. As shown in FIG. 1 , the cross joint 20 includes a cross shaft 2, a rolling bearing portion 5, and a pair of axles 17. The cross shaft 2 has four shaft portions 4. Each rolling bearing portion 5 is disposed on each shaft portion 4.

The cross shaft 2 has a base 3 and four shaft portions 4. The base 3 is provided at the center of the cross shaft 2. The shaft portions 4 extend from the base 3 in four directions along the axes X and Z that are orthogonal to each other. The cross shaft 2 can rotate around the center axis C together with the shaft 17. The center axis C passes through the center of the base 3 and is orthogonal to the axes X and Z of the shaft portions 4. An oil injection path 13 for supplying a lubricant to the inner side of the rolling bearing portion 5 is provided in the cross shaft 2 and in a cross shape along the axes X and Z.

As shown in FIG. 2 , an oiling hole 3a is provided in the base 3 of the cross shaft 2, and an oiling hole 11a is provided in the bearing cup 11 of the rolling bearing portion 5 described later. The oiling holes 3a, 11a are connected to the oiling path 13. The lubricant is supplied into the rolling bearing portion 5 through the oiling holes 3a, 11a and the oiling path 13. In the present embodiment, grease is used as the lubricant. The grease may be supplied during the operation of the device including the cross joint 20, or may be supplied periodically (e.g., every 1-3 months).

Each rolling bearing portion 5 includes the above-mentioned shaft portion 4, a plurality of needle rollers 9, and a bearing cup 11. The needle rollers 9 are arranged along the outer peripheral surface of each shaft portion 4 so as to be able to roll thereon. The bearing cup 11 has a bottomed cylindrical shape. That is, the bearing cup 11 has a cylindrical portion 14 and a disc-shaped portion 15 as a bottom. The bearing cup 11 is mounted on the outer peripheral surface of the shaft portion 4 via the needle rollers 9. The needle rollers 9 roll with the inner peripheral surface (cylindrical portion 14) of the bearing cup 11 as an outer roller and the outer peripheral surface of the shaft portion 4 as an inner roller. This allows the bearing cup 11 to swing about the axis Z of the shaft portion 4. Similarly, the bearing cup 11 adjacent to the above-mentioned bearing cup 11 can swing about the axis X.

As shown in FIG. 1 , a washer 10 is provided between the distal end surface of the shaft portion 4 and the bottom surface of the bearing cup 11. A roller guide 8, a sealing member 7, and an oil baffle 6 are provided in the axial Z direction relative to the needle roller 9 in a position closer to the base 3. The sealing member 7, the oil baffle (second member) 6, and the bearing cup (first member) 11 constitute a sealing structure 1 according to the present disclosure. The oil baffle 6 and the bearing cup 11 are concentrically arranged and rotate relative to each other.

Sealing structure 1

FIG. 3 is a cross-sectional view of the sealing structure 1. FIG. 4 is a cross-sectional view showing the sealing member 7 in a natural state, that is, in a state where the sealing member 7 is not in contact with the oil baffle 6. A lubricating space is provided between the shaft portion 4 and the cylindrical portion 14 of the bearing cup 11. The needle roller 9 is arranged in the lubricating space, and the lubricating space is supplied with grease used as a lubricant. The sealing structure 1 is provided for inhibiting water and the like from entering the lubricating space, and inhibiting the lubricant from leaking out of the lubricating space to the outside. In the present disclosure, the lower side in FIG. 3 is defined as the "first axial direction", and the upper side in FIG. 3 is defined as the "second axial direction". The right side in FIG. 3 is defined as the "first radial direction", and the left side in FIG. 3 is defined as the "second radial direction". These directions do not indicate an absolute specific direction in the axis, but indicate relative directions. Therefore, the terms "first" and "second" can be used interchangeably. The "first radial direction" and "second radial direction" are also the same.

The oil baffle 6 is formed in a ring shape and is fitted and attached to the outer peripheral surface of the shaft portion 4 at its base end. The oil baffle 6 has a cylindrical main body located radially inward of the cylindrical portion 14 of the bearing cup 11. The main body is referred to as an "oil baffle body 6a". The oil baffle body 6a is formed in a cylindrical shape along the outer peripheral surface of the shaft portion 4. The oil baffle 6 has sealing surfaces 41, 42, 43, and the lips 31, 32, 33 of the sealing member 7 are in contact with the sealing surfaces 41, 42, 43, respectively. In addition to the oil baffle body 6a, the oil baffle 6 has a first extension portion 6b and a second extension portion 6c. The first extension portion 6b extends radially outward from the oil baffle body 6a on the first axial side (the lower side in FIG. 3). The second extension portion 6c extends from the radial outer end of the first extension portion 6b in the second axial direction (the upper side in FIG. 3). The oil baffle body 6a, the first extension portion 6b, and the second extension portion 6c are integrally formed as a single component.

On the outer peripheral surface of the oil baffle body 6a, a second sealing surface 42 and a third sealing surface 43 are provided in sequence from the second axial side to the first axial side. The second extension portion 6c has a cylindrical shape and has a first sealing surface 41 on its inner peripheral surface. That is, the second extension portion 6c is provided with a first sealing surface 41 with a radial surface facing inward. The first sealing surface 41 has a cylindrical shape extending along the axial direction. That is, in the present invention, the direction along the center line of the first sealing surface 41 is consistent with the axial direction.

The oil baffle 6 has a third extension portion 6d extending radially outward from the second extension portion 6c. The outer peripheral surface of the second extension portion 6c and the surface of the third extension portion 6d on the second axial side face the end of the cylindrical portion 14 of the bearing cup 11, and there is a gap between them. This gap is used as a sealing gap to prevent water and the like from entering between the oil baffle 6 and the cylindrical portion 14 of the bearing cup 11.

The sealing member 7 has a generally annular shape and is attached to the cylindrical portion 14 of the bearing cup 11. The sealing member 7 seals the space between the bearing cup 11 and the oil baffle 6 and supplies the space with grease (lubricant). To achieve the sealing function, the sealing member 7 has a fixed portion, rubber lips 31, 32, 33, an annular spring (first pressing member) 51, and a supporting portion 45. The fixed portion is composed of a metal member 34.

The metal member (fixing portion) 34 is fitted to the inner peripheral surface of the cylindrical portion 14 of the bearing cup 11 so as to be fixed to the cylindrical portion 14 of the bearing cup 11. The metal member 34 has a first metal member 34a and a second metal member 34b. The first metal member 34a has a first cylindrical portion 34a1 and a first annular portion 34a2. The first annular portion 34a2 extends radially inward from the end of the first cylindrical portion 34a1 on the second axial side. The second metal member 34b has a second cylindrical portion 34b1 and a second annular portion 34b2. The second annular portion 34b2 extends radially inward from the end of the second cylindrical portion 34b1 on the second axial side. The first cylindrical portion 34a1 is fitted to the inner peripheral surface of the cylindrical portion 14 of the bearing cup 11 to be fixed to the cylindrical portion 14 of the bearing cup 11. The second cylindrical portion 34b1 overlaps the radial inner side of the first cylindrical portion 34a1 and is pressed onto the end of the first axial side of the first cylindrical portion 34a1, so that the second metal member 34b is fixed to the first metal member 34a.

The lips 31, 32, 33 include a first lip 31, a second lip 32, and a third lip 33 joined to the metal member 34. The first lip 31 and the third lip 33 are fixed to the second annular portion 34b2 of the second metal member 34b, and the second lip 32 is fixed to the first annular portion 34a2 of the first metal member 34a.

First lip 31

The first lip 31 has a base portion (first portion) 31a, a connecting portion (second portion) 31b, and a contact portion (third portion) 31c. The base portion 31a has a substantially cylindrical shape and extends from the metal member (fixing portion) 34 in the first axial direction. More specifically, the base portion 31a extends in the first axial direction from the side surface of the second annular portion 34b2 on the first axial side. The connecting portion 31b has a substantially annular shape and extends radially outward from the extended end of the base portion 31a (the end of the base portion 31a on the first axial side). The connecting portion 31b connects the end of the base portion 31a on the first axial side and the end of the contact portion 31c on the first axial side. The contact portion 31c has a substantially cylindrical shape and extends in the second axial direction from the extension end of the connecting portion 31b (the radial outer end of the connecting portion 31b). The contact portion 31c is provided with a gap radially outwardly from the base portion 31a and contacts the first sealing surface 41 of the oil retaining ring 6.

The side surface of the contact portion 31c on the radially outer side (the outer peripheral surface of the contact portion 31c) is defined as a facing surface 31c2 facing the first sealing surface 41, and at least a portion of the facing surface 31c2 contacts the first sealing surface 41. Relative to the first sealing surface 41, the base portion 31a is disposed on the side of the contact portion 31c opposite to the first sealing surface 41.

The band spring (first pressing member) 51 is provided between the base portion 31a and the contact portion 31c. More specifically, the band spring 51 is accommodated in a space (accommodation space) S surrounded by the base portion 31a, the connecting portion 31b, and the contact portion 31c. An opening A for inserting the band spring 51 into the accommodation space S is provided between the base portion 31a and the contact portion 31c. The opening A is opened in the second axial direction. The band spring 51 is a coil spring formed in a ring shape. The annular spring 51 elastically deforms in the contraction direction so as to be accommodated in the accommodation space S, and presses the contact portion 31c toward the first sealing surface 41 by elastically returning in the extension direction.

Supporting portion 45 and metal member 34

Here, as described above, the metal member 34 of the present disclosure is composed of a first metal member 34a and a second metal member 34b. The first cylindrical portion 34a1 of the first metal member 34a and the second cylindrical portion 34b1 of the second metal member 34b constitute the cylindrical portion 35 of the metal member 34. The second annular portion 34b2 extends radially inward from the end of the second cylindrical portion 34b1 on the first axial side, which is a part of the cylindrical portion 35. From above, the metal member 34 includes a cylindrical portion 35 attached to the cylindrical portion 14 of the bearing cup 11, and a second annular portion 34b2 extending radially inward from a part of the cylindrical portion 35 (the second cylindrical portion 34b1). The metal member 34 is used as a core material for fixing the sealing member 7 to the bearing cup 11.

The support portion 45 is used as the core material of the first lip 31 of the sealing member 7. That is, the support portion 45 is provided along the base portion 31a of the first lip 31, and suppresses the base portion 31a from deforming radially outward. The support portion 45 of the present disclosure is composed of a metal member separated from the metal member 34. To be used as a core material, the support portion 45 only needs to be made of a material having higher rigidity than the first lip 31 (base portion 31a), which is made of rubber.

The support portion 45 has a support body portion 46 and an auxiliary portion 47. The support body portion 46 is a cylindrical portion extending in the axial direction along the base portion 31a. The support body portion 46 is substantially provided along the entire base portion 31a. More specifically, the support body portion 46 extends from the second annular portion 34b2 in the first axial direction, and the end of the support body portion 46 on the first axial side is located radially inward of the annular spring 51.

The auxiliary portion 47 is used to position the support portion 45. Therefore, the auxiliary portion 47 extends radially inward from the end 46a of the cylindrical support body portion 46 on the second axial side. That is, the auxiliary portion 47 has an annular shape. The auxiliary portion 47 is integral with the support body portion 46, and the surface of the auxiliary portion 47 contacts a portion of the metal member 34 in the axial direction. The support portion 45 has a substantially annular shape and has an L-shape in a cross section including the center line of the sealing structure 1.

The radial inner end 47a of the auxiliary portion 47 protrudes radially inwardly more than the radial inner end 48a of the second annular portion 34b2 of the metal member 34. This structure is provided for accurately positioning the support portion 45 when the sealing member 7 is formed by a mold. This molding by a mold will be described later.

Second lip 32 and third lip 33

The second lip 32 extends from the first annular portion 34a2 in the first axial direction. The second lip 32 contacts the second sealing surface 42 of the oil baffle ring 6 on the radially inner side of the side surface. The recess 32a is provided on the side surface on the radially outer side of the second lip 32. The annular spring (second pressing member) 52 is provided in the recess 32a. The annular spring 52 is provided by forming the coil spring into a circular ring shape. The annular spring 52 elastically deforms in the extension direction so as to be accommodated in the recess 32a, and by elastically returning in the contraction direction, the second lip 32 is pressed against the second sealing surface 42.

The third lip 33 extends in the first axial direction from the end of the second annular portion 34b2 on the radial inner side. The third lip 33 contacts the third sealing surface 43 of the oil retaining ring 6 on the radial inner side of the side surface. The third sealing surface 43 is formed as an inclined surface (conical surface) whose outer diameter gradually decreases from the first axial side to the second axial side. Note that the third lip 33 can be omitted. In the present embodiment, the third sealing surface 43 is formed into a cone shape. However, for example, the third sealing surface 43 may be a cylindrical surface parallel to the axial direction.

Sealing structure 1 and sealing member 7

As shown in FIG. 3 , in the sealing member 7 of the present embodiment, the first lip 31 contacts the first sealing surface 41 disposed in a manner with the radial surface facing inward, and the second lip 32 and the third lip 33 contact the second sealing surface 42 and the third sealing surface 43 disposed in a manner with the radial surface facing outward. Therefore, even if the shaft portion 4 moves in the axial direction relative to the bearing cup 11, the sealing performance will not be reduced.

When the shaft portion 4 moves in a radial direction (for example, to the right side in FIG. 3 ) relative to the bearing cup 11, on the first radial side (the portion shown in FIG. 3 ) of the shaft portion 4, the first lip 31 moves in a direction away from the first sealing surface 41, but the second lip 32 and the third lip 33 move in a direction approaching the second and third sealing surfaces 42, 43. On the second radial side of the shaft portion 4 opposite to the first radial side of the shaft portion 4, the second and third lips 32, 33 move in a direction away from the second and third sealing surfaces 42, 43, but the first lip 31 moves in a direction approaching the first sealing surface 41. Therefore, it is possible to ensure the sealing performance on both sides of the sealing member 7 in the radial direction.

In the oil baffle 6, the second and third sealing surfaces 42, 43 are arranged on the outer peripheral surface of the oil baffle body 6a, and the first sealing surface 41 located radially outward of the second and third sealing surfaces 42, 43 is arranged on the inner peripheral surface of the second extension portion 6c. Therefore, the second sealing surface 42 and the third sealing surface 43, and the first sealing surface 41 are arranged so as to substantially face each other in the radial direction, and there is a space therebetween. The space is used as a space for configuring the sealing member 7 (lips 31, 33). The sealing member 7 is arranged in the space, and the lips 31 to 33 contact the first sealing surface 41 and the second and third sealing surfaces 42, 43 arranged facing each other in the radial direction. Since the third sealing surface 43 is arranged radially inward of the first sealing surface 41, the axial dimension of the sealing structure 1 can be minimized to the greatest extent.

As described above, the sealing structure 1 of the present disclosure seals the inner space (lubricating space) of the rolling bearing portion 5 to be lubricated with grease. Hereinafter, as shown in FIG. 3 , the inner side of the rolling bearing portion 5 relative to the first lip 31 relative to the direction along the first sealing surface 41 (axial direction) is also referred to as the "lubricating space side", and the outer side of the rolling bearing portion 5 relative to the first lip 31 is also referred to as the "lubricating space outer side".

FIG. 7A shows the contact portion 31c of the first lip 31 contacting the first sealing surface 41 in a state before grease is supplied. In this state, a portion of the facing surface 31c2 of the contact portion 31c on the second axial side (outside the lubrication space) contacts the first sealing surface 41, and a portion of the contact portion 31c on the first axial side (lubrication space side) faces the first sealing surface 41 with a small gap s therebetween.

FIG. 7B shows the first lip 31 in a state where lubricant is supplied to the lubrication space. When grease is supplied to the lubrication space, the first lip 31 made of rubber is pressed in the direction of arrow c by the grease supply pressure (internal pressure). Therefore, the portion of the facing surface 31c2 of the contact portion 31c facing the first sealing surface 41 with a small gap s therebetween is driven to contact the first sealing surface 41.

In view of the above, in the sealing structure 1 of the present disclosure, a high-rigidity support portion 45 is provided along the base portion 31a of the first lip 31. This makes it possible to suppress the first lip 31 from strongly pressing the sealing surface 41 due to the pressure of the grease supplied to the lubrication space. The portion of the facing surface 31c2 of the contact portion 31c facing the first sealing surface 41 with a small gap s therebetween is restricted from contacting the first sealing surface 41 through its surface. Therefore, the grease pushes the contact portion 31c upward with the supply pressure and is discharged from the gap between the contact portion 31c and the first sealing surface 41 (refer to arrow d). In this way, old grease can be appropriately replaced with new grease in the lubrication space.

As described above, during maintenance, etc., the grease in the lubrication space is replaced with new grease. The sealing structure 1 of the present disclosure provides a structure in which grease is easily discharged from the gap between the contact portion 31c and the first sealing surface 41. In the sealing structure 1 of the present disclosure, in addition to the function of the support portion 45 as described above, a groove 61 is provided in the contact portion 31c of the first lip 31, so that the grease discharge performance can be further improved. Hereinafter, it will be described.

Function of the groove 61 of the first lip 31

As shown in FIG. 5 , the contact portion 31c of the first lip 31 has a side surface (hereinafter, also referred to as a "facing surface") 31c2 facing the first sealing surface 41. A groove 61 is provided in the facing surface 31c2. The groove 61 extends in the axial direction from the end of the contact portion 31c on the lubricating space side toward the outside of the lubricating space. As shown in FIGS. 6A and 6B , the grooves 61 are provided at a plurality of positions at certain intervals in the circumferential direction of the first lip 31. For example, the grooves 61 are formed at 16 positions at equal intervals in the circumferential direction of the first lip 31. The cross section (cross section in a direction perpendicular to the axis) of the bottom surface of each groove 61 of the present embodiment has a substantially arcuate shape.

Each groove 61 includes a deep groove portion 61a on the lubricating space side and a shallow groove portion 61b on the outer side of the lubricating space. The bottom surfaces of the deep groove portion 61a and the shallow groove portion 61b are inclined relative to the first sealing surface 41, so that the axial depth thereof is deeper on the lubricating space side. The inclination of the bottom surface of the deep groove portion 61a is greater than the inclination of the bottom surface of the shallow groove portion 61b. As shown in FIGS. 6A and 6B, the circumferential width W3 of the deep groove portion 61a and the shallow groove portion 61b is substantially the same. As described above, the groove 61 has a larger cross-sectional area on the lubricating space side and a smaller cross-sectional area on the outside of the lubricating space.

As described above, FIG. 7A shows the contact portion 31c of the first lip 31 contacting the first sealing surface 41. In this state, a portion of the facing surface 31c2 of the contact portion 31c on the second axial side (outside the lubrication space) contacts the first sealing surface 41, and a portion of the facing surface 31c2 of the contact portion 31c on the first axial side (lubrication space side) faces the first sealing surface 41, with a small gap s therebetween.

As described above, FIG. 7B shows the first lip 31 in a state where grease is supplied to the lubrication space. When grease is supplied to the lubrication space, the first lip 31 is pressed in the direction of arrow c by the supply pressure (internal pressure) of the grease. At this time, the support portion 45 suppresses deformation of the first lip 31. However, it is assumed here that the facing surface 31c2 of the contact portion 31c, which faces the first sealing surface 41 and has a small gap s therebetween, contacts the first sealing surface 41.

At this time, as shown in FIG. 6B , the area of the facing surface 31c2 of the contact portion 31c located further in the second axial direction of the position L corresponds to the full contact area R1. The end of the groove 61 on the second axial side (outer side of the lubrication space) is arranged at the position L. In the full contact area R1, the entire circumference (entire surface) of the facing surface 31c2 of the contact portion 31c contacts the first sealing surface 41. Furthermore, the area of the facing surface 31c2 of the contact portion 31c on the first axial side of the position L is a partial contact area R2, in which the facing surface 31c2 of the contact portion 31c contacts the first sealing surface 41 discontinuously (intermittently) in the circumferential direction due to the groove 61. That is, the facing surface 31c2 of the contact portion 31c has a complete contact area R1 and a partial contact area R2.

Therefore, as shown in FIG. 7B , even when the first lip 31 is pressed in the direction of arrow c by grease, the surface of the groove 61 of the partial contact area R2 does not contact the first sealing surface 41. Therefore, the grease in the lubrication space enters the groove 61, pushes the contact portion 31c upward by its supply pressure, and is discharged from the gap between the full contact area R1 of the contact portion 31c and the first sealing surface 41 (refer to arrow d). In this way, the old grease can be properly replaced with new grease in the lubrication space.

As described above, since the cross-sectional area of the groove 61 on the lubrication space side is larger than the cross-sectional area on the outside of the lubrication space, grease can easily flow into the groove 61, and the grease discharge performance during grease supply is improved.

As shown in FIG. 7B , in the facing surface 31c2 of the contact portion 31c, the boundary L between the full contact area R1 and the partial contact area R2 is located in the axial range D between the end 51b of the endless spring 51 on the first axial side (lubricating space side) and the center 51a of the endless spring 51. This structure is provided for the following reason. That is, if the boundary L is located on the first axial side relative to the end 51b, it is difficult for grease to enter the groove 61 to push the full contact area R1 of the facing surface 31c2. If the boundary L is set on the second axial side (outside the lubrication space) relative to the center 51a, the sealing performance of the contact portion 31c is reduced due to the surface pressure of the complete contact area R1.

Figures 8A and 8B show that the surface pressure of the full contact area R1 on the first sealing surface 41 changes when the grease supply pressure acts on the first lip 31. As shown in Figure 8A, when the boundary L between the full contact area R1 and the partial contact area R2 coincides with the center 51a of the annular spring 51, the surface pressure of the full contact area R1 on the first sealing surface 41 indicates the peak value of the end on the lubricating space side (see point P1). Therefore, water and the like easily enter from the gap between the facing surface 31c2 and the first sealing surface 41 on the outer side of the lubricating space.

As shown in FIG. 8B , when the boundary L between the full contact area R1 and the partial contact area R2 is located closer to the lubricating space side relative to the center 51a of the annular spring 51, the surface pressure of the full contact area R1 on the first sealing surface 41 indicates the peak value of the end on the outside of the lubricating space (see point P2). Therefore, water or the like can be properly suppressed from entering the gap between the facing surface 31c2 on the outside of the lubricating space and the first sealing surface 41, and the sealing performance can be properly maintained.

9A and 9B are schematic diagrams corresponding to FIGS. 6A and 6B and show the modification of the groove 61 of the first lip 31. In the modified groove 61, the width W4 of the deep groove portion 61a in the circumferential direction is greater than the width W3 of the shallow groove portion 61b. The cross-sectional shape of the deep groove portion 61a has a substantially circular arc shape. According to the modification, the cross-sectional shape of the deep groove portion 61a can be made larger, which enables grease to flow into the groove 61 easily.

Molding seals with molds7

The sealing member 7 (refer to FIG. 4 ) includes rubber lips 31, 32, 33, a metal member (fixing portion) 34 for fixing the lips 31, 32, 33, and a supporting portion 45 used as a core material of the first lip 31. The sealing member 7 having this structure is formed by a mold. More specifically, in a state where the first metal member 34a is fixed to a part of the mold, the second lip 32 is vulcanized and molded in the mold, and the first metal member 34a and the second lip 32 are integrated. Furthermore, in a state where the second metal member 34b is fixed to another part of the mold, the first lip 31 and the third lip 33 are vulcanized and molded in the mold, and the second metal member 34b, the first lip 31, and the third lip 33 are integrated. When the first lip 31 is vulcanized and molded, the supporting portion 45 is fixed to the mold.

FIG. 10 is an explanatory diagram showing a state where the support portion 45 is fixed to the mold. As shown in FIG. 10 , a portion 65 of the mold contacts the radial inner end 47a of the auxiliary portion 47 of the support portion 45. When the support portion 45 is embedded in the first lip 31, the support portion 45 is positioned in the radial direction. Note that the portion 65 of the mold partially contacts the radial inner end 47a of the auxiliary portion 47 in the circumferential direction. Therefore, a rubber portion is formed in a portion other than the portion 65.

When the mold is used to integrally form the sealing member 7 including the rubber lips 31, 33, the support portion 45, and the second metal member 34b, the surface of the auxiliary portion 47 is brought into contact with a portion of the second metal member 34b in the axial direction. This facilitates the positioning of the support portion 45 and the second metal member 34b in the axial direction. Furthermore, another portion 66 of the mold contacts the surface of the auxiliary portion 47 on the first axial side. This ensures the positioning of the support portion 45 in the axial direction. Another portion 66 of the mold partially contacts the surface of the auxiliary portion 47 in the circumferential direction. Therefore, a rubber portion is formed in a portion other than portion 66.

other

As described above, the support portion 45 has an L-shape in a cross section including the center line of the sealing structure 1. The metal member 34 is substantially U-shaped as a whole, and is constructed by overlapping the first metal member 34a and the second metal member 34b. Each of the support portion 45, the first metal member 34a, and the second metal member 34b has an L-shape in a cross section including the center line of the sealing structure 1. As described above, in the present disclosure, the support portion 45 is provided separately from the metal member 34. In the metal member 34, the first metal member 34a and the second metal member 34b are provided separately. In the present disclosure, the first metal member 34a, the second metal member 34b, and the support portion 45 have a shape with a curved portion. However, the first metal member 34a, the second metal member 34b, and the supporting portion 45 can be manufactured separately, which facilitates the manufacturing thereof.

The present invention is not limited to the above embodiments and can be modified within the scope of the present invention described in the claims. For example, the support portion 45 can be integrated with the metal member 34 (the second metal member 34b). For example, the number, axial length, circumferential width, and cross-sectional shape of the grooves 61 provided in the contact portion 31c of the first lip 31 can be appropriately changed. The sealing structure 1 of the present disclosure can be applied to a portion other than the portion between the shaft portion 4 and the bearing cup 11 in the cross joint 20.

1: Sealing structure

4: Shaft part

6: Oil retaining ring

6a: Oil retaining ring body

6b: First extension part

6c: Second extension part

6d: The third extension

7: Sealing components

8: Roller guide

9: Rolling needle

11: Bearing cup

14: Cylindrical part

31: Lips

31a: Base part

31b: Connection part

31c: Contact part

31c2: Surface facing

32: Lips

32a: Concave part

33: Lips

34:Metal components

34a: First metal component

34a1: first cylindrical part

34a2: First annular part

34b: Second metal component

34b1: Second cylindrical part

34b2: Second annular part

35: Cylindrical part

41: Sealing surface

42: Sealing surface

43: Sealing surface

45: Support part

46: Support the main body

47: Auxiliary part

51: Ring spring

52: Ring spring

A: Opening

S: Accommodation space

Claims (4)

A sealing structure (1) is characterized by comprising: a first component (11) having a cylindrical portion; a second component (6) having a main body (6a), the main body (6a) being located radially inward of the cylindrical portion and being arranged concentrically with the first component (11) so as to rotate relative to the first component (11); and an annular sealing component (7) attached to the first component (11) and constructed to seal the space between the first component (11) and the second component (6) so as to supply a lubricant to the space, wherein: the second component (6) further comprises a first extension portion (6b) and a second extension portion (6c), the first extension portion (6b) extending radially outward from a portion of the main body (6a) on a first axial side, the second extension portion (6c) extending radially outward from a portion of the main body (6a) on a first axial side, The first extension portion (6c) extends from the radial outer end of the first extension portion (6b) in the second axial direction and is provided with a sealing surface (41) with a radial surface facing inward; and the annular sealing member (7) includes: a fixing portion fixed to the first member (11), a rubber lip (31) having a base portion (31a), a contact portion (31c), and a connecting portion (31b), wherein the base portion (31a) extends from the fixing portion in the first axial direction, the contact portion (31c) is provided with a gap between the contact portion (31c) and the base portion (31a) at a radially outer portion of the base portion (31a) and is constructed to contact the sealing surface (41), and the connecting portion (31b) is connected to a portion of the base portion (31a) on the first axial side. The first axial side of the contact portion (31c) is provided with a pressing member disposed between the base portion (31a) and the contact portion (31c) to press the contact portion (31c) toward the sealing surface (41); and a supporting portion (45) is disposed along the base portion (31a) and has a higher rigidity than the base portion (31a). The fixing portion comprises a metal member (34) attached to the first member (11); the supporting portion (45) is separated from the metal member (34), and the supporting portion (45) comprises a cylindrical supporting body portion (46) and an auxiliary portion (47), wherein the cylindrical supporting body portion (46) extends along the base portion (31a) in an axial direction, and the auxiliary portion (47) The auxiliary portion (47) is integrally formed with the cylindrical supporting body portion (46) and is constructed to contact a portion of the metal member (34) in the axial direction, the auxiliary portion (47) extends radially inwardly in the second axial direction from the end portion (46a) of the cylindrical supporting body portion (46), and the lubricant is supplied to the cylindrical portion of the first member (11) and the second member ( 6) and is supplied from the second axial side of the space, and due to the pressure of the lubricant supplied, the lubricant in the space is discharged from the gap between the contact portion (31c) and the sealing surface (41) of the second extension portion (6c) through the gap between the connecting portion (31b) and the first extension portion (6b). A sealing structure (1) as claimed in claim 1, wherein: the metal member (34) has a cylindrical portion attached to the first member (11) and an annular portion extending radially inward from the cylindrical portion; the auxiliary portion (47) extends radially inward from the second axial end of the cylindrical supporting body portion (46) and has an annular shape; and the radial inner end of the auxiliary portion (47) further protrudes radially inward relative to the radial inner end of the annular portion. A sealing structure (1) is characterized by comprising: a first component (11) having a cylindrical portion; a second component (6) having a main body (6a), the main body (6a) being located radially inward of the cylindrical portion and being arranged concentrically with the first component (11) so as to rotate relative to the first component (11); and an annular sealing component (7) attached to the first component (11) and constructed to seal the space between the first component (11) and the second component (6) so as to supply a lubricant to the space, wherein: the second component (6) further comprises a first extension portion (6b) and a second extension portion (6c), the first extension portion The first extension portion (6b) extends radially outward from a portion of the main body (6a) on the first axial side, the second extension portion (6c) extends from the radial outer end of the first extension portion (6b) in the second axial direction, and is provided with a sealing surface (41) with a radial surface facing inward; and the annular sealing member (7) comprises: a fixing portion fixed to the first member (11), a rubber lip (31) having a base portion (31a), a contact portion (31c), and a connecting portion (31b), the base portion (31a) extending from the fixing portion in the first axial direction, the contact portion (31c) being provided radially outward from the base portion (31a) The contact portion (31c) has a gap between the contact portion (31c) and the base portion (31a) and is constructed to contact the sealing surface (41), and the connecting portion (31b) connects a portion of the base portion (31a) on the first axial side and a portion of the contact portion (31c) on the first axial side, a pressing member is provided between the base portion (31a) and the contact portion (31c) to press the contact portion (31c) toward the sealing surface (41), and a supporting portion (45) is provided along the base portion (31a) and has a higher rigidity than the base portion (31a), wherein the contact portion (31c) has a surface The facing surface (31c2) faces the sealing surface (41); and the facing surface (31c2) has a full contact area (R1) and a partial contact area (R2), the full contact area (R1) is arranged in a portion of the facing surface (31c2) on a second axial side corresponding to the outer side of the space, and is constructed to contact the sealing surface (41) on the entire circumference of the full contact area (R1), and the partial contact area (R2) is arranged in a portion of the facing surface (31c2) on a first axial side corresponding to the space side, and is constructed to contact the sealing surface (41) discontinuously in the circumferential direction of the partial contact area (R2). The sealing structure (1) of claim 3, wherein: the pressing member is an annular spring (51); and the boundary (L) between the full contact area (R1) and the partial contact area (R2) is located in the axial range between the end of the annular spring (51) on the first axial side and the center (51a) of the annular spring (51).

Images