Sliding constant velocity universal joint

Abstract

In a sliding constant velocity universal joint equipped with a sealing mechanism for sealing the opening of the outer joint member on the outer circumference of the shaft, the maximum operating angle is increased. [Solution] A sliding constant velocity universal joint 1 is provided with a sealing mechanism 9 for sealing the opening 2a of the outer joint member 2 on the outer circumference of the shaft 6. The sealing mechanism 9 comprises a cover 10 connected to the outer joint member 2, a seal outer ring 13 that can be displaced relative to the cover 10, a seal inner ring 11 mounted on the outer circumference of the shaft 6, a seal middle ring 12 interposed between the seal outer ring 13 and the seal inner ring 11, and a compression coil spring 14 that pushes the seal outer ring 13 toward the opening 2a. In this joint 1, an increase in the outer diameter of the seal inner ring 11 and the seal middle ring 12 can be avoided, and when the joint 1 takes an operating angle, both rings 11 and 12 are less likely to interfere with the outer joint member 2 or the cover 10. As a result, a higher maximum operating angle θ can be achieved.

Description

Technical Field

[0001] The present disclosure relates to a sliding constant velocity joint.

Background Art

[0002] In a sliding constant velocity joint used as a power transmission mechanism for various industrial machines, as a seal structure for preventing the intrusion of foreign matter and water from the outside of the joint and the leakage of lubricant from the inside of the joint, it is common to adopt boots made of rubber or resin.

[0003] However, for example, a sliding constant velocity joint adopted in a steel manufacturing facility may be used in a harsh environment where radiant heat of 80°C or higher, high temperature and high humidity due to steam, and scattering of scale and chemicals occur. Therefore, the boots are likely to deteriorate, leading to premature breakage of the boots.

[0004] Therefore, in such a harsh environment as described above, instead of a sliding constant velocity joint provided with rubber or resin boots, it is preferable to use a sliding constant velocity joint provided with a metal seal structure as disclosed in Patent Document 1.

[0005] As shown in FIG. 5, the sliding constant velocity joint 100 disclosed in Patent Document 1 includes an outer joint member 200 in which an opening 200a is formed, an inner joint member 300 housed in the inner periphery of the outer joint member 200, a plurality of balls 400 for transmitting torque between the outer joint member 200 and the inner joint member 300, a cage 410 for holding the plurality of balls 400, and a shaft 500 having one end assembled to the inner periphery of the inner joint member 300.

[0006] The sliding constant velocity joint 100 includes, as its seal structure, a seal mechanism 600 for sealing the opening 200a of the outer joint member 200 on the outer peripheral side of the shaft 500 extending from the inner joint member 300.

[0007] The sealing mechanism 600 includes a cylindrical cover 610 connected to the outer joint member 200, a sealing outer ring 620 that can be displaced axially (left-right in Figure 5) along the inner circumference of the cover 610, a sealing inner ring 630 mounted on the outer circumference of the shaft 500 and in contact with the sealing outer ring 620 from the opening 200a side, and a compression coil spring 640 that pushes the sealing outer ring 620 toward the opening 200a side along the axial direction.

[0008] The inner ring 630 of the seal has a partially convex spherical surface 630a on its outer circumference. On the other hand, the outer ring 620 of the seal has a sealing portion 621 on its inner circumference that is slidable with the partially convex spherical surface 630a. The sliding surface of the sealing portion 621 with the partially convex spherical surface 630a is formed as a partially concave spherical surface 621a having the same spherical radius as the partially convex spherical surface 630a.

[0009] In the sliding constant velocity universal joint 100, as shown in Figure 6, when the joint 100 takes an operating angle, the inner seal ring 630, one of the components of the seal mechanism 600, changes its orientation. At this time, the state in which both the partially convex spherical surface 630a of the inner seal ring 630 and the partially concave spherical surface 621a of the outer seal ring 620 are in contact is maintained, thereby ensuring the sealing performance of the joint 100 by the seal portion 621. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] Patent No. 6356027 [Overview of the project] [Problems that the invention aims to solve]

[0011] The maximum operating angle θ in the sliding constant velocity universal joint 100 described above is the angle at which the shaft 500 and the seal outer ring 620 interfere, as shown enclosed in circle A in Figure 6. The maximum operating angle θ is limited to, for example, about 10°. However, depending on the industrial machinery employing the sliding constant velocity universal joint 100, a maximum operating angle θ higher than 10° may be required.

[0012] In order to increase the maximum operating angle θ, as shown in Figure 7, it is possible to accommodate the increased angle by enlarging the inner diameter of the seal outer ring 620 (from the dashed line to the solid line) and then extending the partial convex spherical surface 630a of the seal inner ring 630 (from the dashed line to the solid line) in accordance with the enlargement.

[0013] However, even when attempting to increase the maximum operating angle θ as described above, there is a problem in that the extended portion of the convex spherical surface 630a of the seal inner ring 630 interferes with the outer joint member 200 and the cover 610 at the location circled B in Figure 8. This problem arises because, as the portion of the convex spherical surface 630a is extended and enlarged, the outer diameter of the seal inner ring 630 also increases. As a result, when the joint 100 takes an operating angle, the seal inner ring 630, which has changed its orientation, is more likely to come into contact with the outer joint member 200 and the cover 610. Consequently, the maximum operating angle θ has not been increased as desired.

[0014] In light of the circumstances described above, the challenge to be addressed is to achieve a higher maximum operating angle in a sliding constant velocity universal joint equipped with a sealing mechanism for sealing the opening of the outer joint member on the outer circumference of the shaft. [Means for solving the problem]

[0015] A first sliding constant velocity universal joint for solving the above problems comprises: an outer joint member having an opening; an inner joint member housed on the inner circumference of the outer joint member in a state that allows angular and axial displacement relative to the outer joint member; a torque transmission member for transmitting torque between the outer joint member and the inner joint member; a shaft with one end attached to the inner circumference of the inner joint member; and a sealing mechanism that seals the opening of the outer joint member on the outer circumference side of the shaft extending from the inner joint member, wherein the sealing mechanism comprises a cylindrical portion connected to the outer joint member and a portion arranged along the inner circumference of the cylindrical portion, and the axial displacement relative to the cylindrical portion is The seal comprises a possible outer seal ring, an inner seal ring mounted on the outer circumference of a shaft extending from an inner joint member, a middle seal ring interposed between the outer seal ring and the inner seal ring, contacting the outer seal ring from the opening side and the inner seal ring from the opposite side of the opening, and an elastic member that pushes the outer seal ring toward the opening side along the axial direction, wherein the inner seal ring has a partially convex spherical surface on its outer circumference, the middle seal ring has a middle ring seal portion on its inner circumference that can slide against the partially convex spherical surface of the inner seal ring, and the outer seal ring has a partially convex spherical surface on its outer circumference, and the outer seal ring has an outer ring seal portion on its inner circumference that can slide against the partially convex spherical surface of the middle seal ring.

[0016] Here, "cylindrical portion connected to the outer joint member" includes both cases: one in which a cylindrical member separate from the outer joint member is arranged to connect to the outer joint member to constitute the cylindrical portion; and another in which a cylindrical portion formed integrally with the outer joint member connects to the outer joint member to constitute the cylindrical portion.

[0017] In the first sliding constant velocity universal joint, the sealing mechanism includes a sealing outer ring and a sealing inner ring, as well as a sealing intermediate ring interposed between the two rings. In this sealing mechanism, the sealing performance of the joint is ensured by maintaining a state in which the outer ring sealing portion of the sealing outer ring is in contact with the partially convex spherical surface of the sealing intermediate ring, and a state in which the intermediate ring sealing portion of the sealing intermediate ring is in contact with the partially convex spherical surface of the sealing inner ring. In the first sliding constant velocity universal joint, the sealing inner ring and the sealing intermediate ring change their positions when the joint takes an operating angle. Furthermore, in this joint, it is possible to avoid increasing the outer diameter of the sealing inner ring and sealing intermediate ring that change their positions. This is because, compared to the case where only the sealing outer ring and sealing inner ring exist, if a sealing intermediate ring is also present, even if the inner diameter of the sealing outer ring is enlarged to increase the maximum operating angle, sealing performance can be ensured without enlarging the partially convex spherical surfaces of the sealing inner ring and sealing intermediate ring in accordance with the enlargement. As described above, the first sliding constant velocity universal joint avoids increasing the outer diameter of the inner seal ring and the middle seal ring. Therefore, when the joint takes an operating angle, the partially convex spherical surfaces of the inner seal ring and the middle seal ring are less likely to interfere with the outer joint member or cylindrical part. Consequently, the first sliding constant velocity universal joint makes it possible to achieve a higher maximum operating angle.

[0018] The second sliding constant velocity universal joint is a configuration in which the spherical center of the partially convex spherical surface of the inner ring of the seal and the spherical center of the partially convex spherical surface of the middle ring of the seal are offset to the opposite side in the axial direction with respect to the joint center.

[0019] Here, the "joint center" refers to the position where the axis of the outer joint member and the axis of the shaft intersect when the joint is at its operating angle.

[0020] When the spherical center of the partial convex spherical surface of the seal inner ring coincides with the spherical center of the partial convex spherical surface of the seal middle ring (in the case of concentricity), when the joint takes the operating angle, the position of the seal middle ring is not determined, and there is a risk that the seal middle ring will move improperly along the partial convex spherical surface of the seal inner ring. On the other hand, if the spherical center of the partial convex spherical surface of the seal inner ring and the spherical center of the partial convex spherical surface of the seal middle ring are offset, like the second sliding constant velocity universal joint, the seal middle ring is positioned, and it becomes possible to reliably avoid the above-mentioned improper movement.

Effect of the Invention

[0021] According to the sliding constant velocity universal joint of the present disclosure, it is possible to realize an increase in the maximum operating angle.

Brief Description of the Drawings

[0022] [Figure 1] It is a cross-sectional view showing a sliding constant velocity universal joint. [Figure 2] It is a cross-sectional view showing a sliding constant velocity universal joint. [Figure 3] It is a cross-sectional view showing a sliding constant velocity universal joint. [Figure 4] It is a cross-sectional view showing a sliding constant velocity universal joint. [Figure 5] It is a cross-sectional view showing a conventional sliding constant velocity universal joint. [Figure 6] It is a cross-sectional view showing a conventional sliding constant velocity universal joint. [Figure 7] It is a cross-sectional view showing a conventional sliding constant velocity universal joint. [Figure 8] It is a cross-sectional view showing a conventional sliding constant velocity universal joint.

Mode for Carrying Out the Invention

[0023] Hereinafter, embodiments of the sliding constant velocity universal joint will be described with reference to the accompanying drawings. In this embodiment, a double offset type constant velocity universal joint (DOJ), which is a kind of sliding constant velocity universal joint, will be exemplified.

[0024] Figures 1 and 2 show the sliding constant velocity universal joint 1 (hereinafter simply referred to as constant velocity universal joint 1) in a state where it has not taken up an operating angle (operating angle is 0°). On the other hand, Figures 3 and 4 show the constant velocity universal joint 1 in a state where it has taken up its maximum operating angle θ. Note that Figure 4 shows the slide-out state. In this state, the internal components consisting of the inner joint member 3, multiple balls 4, cage 5, and shaft 6 are slid furthest toward the opening 2a side (right side in Figure 4) relative to the outer joint member 2.

[0025] Here, in the description of the following embodiments, "axial direction" means the direction in which the axis 2x of the outer joint member 2 and the axis 6x of the shaft 6 extend when the sliding constant velocity universal joint 1 is not operating (operating angle is 0°).

[0026] As shown in Figure 1, the constant velocity universal joint 1 comprises an outer joint member 2, an inner joint member 3, a plurality of balls 4, a cage 5, and a shaft 6.

[0027] The outer joint member 2 is cylindrical in shape, with an opening 2a formed at its end 2d. Multiple outer track grooves 2c extending in the axial direction are formed on the inner circumferential surface 2b of the outer joint member 2. The multiple outer track grooves 2c are formed at intervals in the circumferential direction of the inner circumferential surface 2b. A lubricant such as grease is sealed inside the internal space of the outer joint member 2.

[0028] The inner joint member 3 is housed within the inner circumference of the outer joint member 2, allowing for angular and axial displacement relative to the outer joint member 2. The outer circumferential surface 3b of the inner joint member 3 is formed as a partially convex spherical surface. Multiple inner track grooves 3c extending in the axial direction are formed on the outer circumferential surface 3b of the inner joint member 3. The multiple inner track grooves 3c are formed at intervals in the circumferential direction of the outer circumferential surface 3b so as to be paired with the outer track grooves 2c of the outer joint member 2. An axial hole 3a for inserting one end of the shaft 6 is formed on the inner circumference of the inner joint member 3.

[0029] Each of the multiple balls 4 functions as a torque transmission member that transmits torque between the outer joint member 2 and the inner joint member 3. Each ball 4 is capable of rolling along the outer track groove 2c of the outer joint member 2 and the inner track groove 3c of the inner joint member 3. The number of balls 4 is often 6 or 8, but it can be any number.

[0030] The cage 5 is formed in an annular shape and interposed between the outer joint member 2 and the inner joint member 3. The cage 5 has multiple pockets 5a formed along the circumferential direction of the ring, each of which accommodates multiple balls 4. The cage 5 is slidable with the inner circumferential surface 2b of the outer joint member 2 and the outer circumferential surface 3b of the inner joint member 3. The sliding surface 5b of the cage 5 with the inner circumferential surface 2b of the outer joint member 2 (part of the outer circumferential surface of the cage 5) is formed as a partially convex spherical surface. On the other hand, the sliding surface 5c of the cage 5 with the outer circumferential surface 3b of the inner joint member 3 (part of the inner circumferential surface of the cage 5) is formed as a partially concave spherical surface.

[0031] One end of the shaft 6 is assembled to the inner joint member 3. The other end of the shaft 6 is press-fitted into the axial hole 3a of the inner joint member 3 and spline-fitted. A pair of C-shaped retaining rings 7 and 8 are fitted around the outer circumference of the shaft 6, with the inner joint member 3 in between. The pair of C-shaped retaining rings 7 and 8 fix the axial position of the inner joint member 3 relative to the shaft 6.

[0032] As shown in Figures 3 and 4, the constant velocity universal joint 1 enters an operating angle state (operating angle greater than 0°) as an angular displacement occurs between the outer joint member 2 and the shaft 6 extending from the inner joint member 3. At this time, the multiple balls 4 housed in the multiple pockets 5a of the cage 5 are always positioned on the plane that bisects the angle of intersection between the axis 2x of the outer joint member 2 and the axis 6x of the shaft 6. This ensures the constant velocity of the constant velocity universal joint 1.

[0033] As can be seen from the comparison between Figure 3 and Figure 4, since this constant velocity universal joint 1 is of the sliding type, it is possible to displace (slide) the internal components, which consist of the inner joint member 3, multiple balls 4, cage 5, and shaft 6, in the axial direction on the inner circumference of the outer joint member 2.

[0034] As shown in Figure 1, the constant velocity universal joint 1 further comprises a metal sealing mechanism 9 for sealing the opening 2a of the outer joint member 2. The sealing mechanism 9 seals the opening 2a on the outer circumference of the shaft 6 extending from the inner joint member 3. The sealing mechanism 9 includes a cover 10 as a cylindrical part, a sealing inner ring 11, a sealing middle ring 12, a sealing outer ring 13, and a compression coil spring 14 as an elastic member.

[0035] The cover 10 is cylindrical in shape and is connected to the end 2d of the outer joint member 2 (the end on the side where the opening 2a is formed). One end of the cover 10 is fixed to the end 2d of the outer joint member 2 by a bolt 15. A disc-shaped plate 16 with a through hole (circular hole) in the center is fixed to the other end of the cover 10 by a bolt 17. The diameter of the through hole in the plate 16 is such that it does not come into contact with the shaft 6 even when the constant velocity universal joint 1 is at its maximum operating angle θ. The plate 16 supports one end of the compression coil spring 14.

[0036] Although not shown in the illustration, the cover 10 may be provided with a plug or the like for supplying lubricant to the internal space of the outer joint member 2.

[0037] As a modification of this embodiment, instead of providing a cover 10 connected to the outer joint member 2, a cylindrical portion formed integrally with the outer joint member 2 may be provided.

[0038] The seal inner ring 11 is formed in an annular shape with a through hole (circular hole) in the center. The seal inner ring 11 is mounted on the outer circumference of the shaft 6 extending from the inner joint member 3. The seal inner ring 11 is sandwiched between a step 6a formed on the outer circumference of the shaft 6 and the C-shaped retaining ring 8, and its axial position relative to the shaft 6 is fixed. This ensures that the relative positional relationship between the seal inner ring 11 and the joint center O is always maintained.

[0039] The seal inner ring 11 has a partially convex spherical surface 11a on its outer circumference. The partially convex spherical surface 11a is formed such that the outer diameter of the seal inner ring 11 gradually increases as it moves toward the opening 2a side (left side in Figure 1).

[0040] As shown in Figures 3 and 4, the inner seal ring 11 changes its orientation while sliding with the inner seal portion 12b of the inner seal ring 12, which will be described later, as the constant velocity universal joint 1 takes an operating angle. At this time, regardless of the magnitude of the operating angle taken by the constant velocity universal joint 1, the axis of the inner seal ring 11 is kept in a state that coincides with the axis 6x of the shaft 6. The partially convex spherical surface 11a of the inner seal ring 11 can enter the inner circumference side of the cage 5 when the constant velocity universal joint 1 takes an operating angle.

[0041] As shown in Figure 1, the seal inner ring 12 is formed in an annular shape with a through hole (circular hole) in the center. The outer diameter (maximum outer diameter) and inner diameter of the seal inner ring 12 are larger than the outer diameter (maximum outer diameter) and inner diameter of the seal inner ring 11, respectively, and smaller than the outer diameter and inner diameter of the seal outer ring 13. The seal inner ring 12 is interposed between the seal inner ring 11 and the seal outer ring 13. The seal inner ring 12 contacts the seal outer ring 13 from the side of the opening 2a, and contacts the seal inner ring 11 from the side opposite to the opening 2a (right side in Figure 1).

[0042] The seal inner ring 12 has a partially convex spherical surface 12a on its outer circumference. The partially convex spherical surface 12a is formed such that the outer diameter of the seal inner ring 12 gradually increases as it moves toward the opening 2a side.

[0043] The sealing ring 12 has a sealing ring portion 12b on its inner circumference that is slidable with the partially convex spherical surface 11a of the sealing inner ring 11. The sealing ring portion 12b has a tapered surface 12c that contacts the partially convex spherical surface 11a of the sealing inner ring 11. The tapered surface 12c is a partially conical surface whose inner diameter gradually increases as it moves toward the opening 2a side. The tapered surface 12c of the sealing ring portion 12b and the partially convex spherical surface 11a of the sealing inner ring 11 are in line contact along the entire circumference in the circumferential direction of the ring. As a result, the contact pressure between the sealing ring portion 12b and the partially convex spherical surface 11a can be increased compared to when the sealing ring portion 12b and the partially convex spherical surface 11a are in surface contact, thereby improving the sealing performance.

[0044] As shown in Figures 3 and 4, the seal ring 12 changes its orientation as the constant velocity universal joint 1 takes on an operating angle, sliding against the partially convex spherical surface 11a of the seal inner ring 11 and the outer ring seal portion 13b of the seal outer ring 13, which will be described later. At this time, the axis of the seal ring 12 is inclined with respect to the axis 6x of the shaft 6.

[0045] As shown in Figure 1, the seal ring 13 is formed in an annular shape with a through hole (circular hole) in the center. The seal ring 13 is positioned along the inner circumference of the cover 10. A small gap is formed between the outer circumferential surface 13a of the seal ring 13 and the inner circumferential surface 10a of the cover 10. This allows the outer circumferential surface 13a of the seal ring 13 to slide against the inner circumferential surface 10a of the cover 10, and the seal ring 13 can be displaced axially relative to the cover 10.

[0046] Although not shown in the diagram, an annular groove may be provided on the outer circumferential surface 13a of the seal outer ring 13, and an O-ring made of a material with a low coefficient of friction (for example, a fluororesin) may be fitted into the groove. In addition, to facilitate the axial displacement of the seal outer ring 13 relative to the cover 10, a groove for oil retention may be provided on the outer circumferential surface 13a of the seal outer ring 13.

[0047] The seal outer ring 13 has a support surface 13d that supports the other end of the compression coil spring 14. The support surface 13d faces a plate 16 fixed to the other end of the cover 10, with an axial gap between them.

[0048] The outer ring of the seal 13 has an outer ring sealing portion 13b on its inner circumference that is slidable with the partially convex spherical surface 12a of the inner ring of the seal 12. The inner diameter of the outer ring of the seal 13 is defined by this outer ring sealing portion 13b. The outer ring sealing portion 13b has a tapered surface 13c that contacts the partially convex spherical surface 12a of the inner ring of the seal 12. The tapered surface 13c is a partially conical surface whose inner diameter gradually increases as it moves toward the opening 2a side. The tapered surface 13c of the outer ring sealing portion 13b and the partially convex spherical surface 12a of the inner ring of the seal 12 are in line contact along the entire circumference in the circumferential direction of the ring. As a result, the contact pressure between the outer ring sealing portion 13b and the partially convex spherical surface 12a is increased compared to when the outer ring sealing portion 13b and the partially convex spherical surface 12a are in surface contact, thereby improving the sealing performance.

[0049] As shown in Figures 3 and 4, the outer seal ring 13 can be displaced axially while sliding against the inner circumferential surface 10a of the cover 10 and the partially convex spherical surface 12a of the inner seal ring 12 as the constant velocity universal joint 1 takes on an operating angle. The maximum operating angle θ of the constant velocity universal joint 1 is the angle at which the shaft 6 and the outer seal ring 13 (outer ring seal portion 13b) interfere.

[0050] As a variation of this embodiment, instead of the tapered surfaces 12c and 13c of the inner ring seal portion 12b and the outer ring seal portion 13b, a partially concave spherical surface that contacts the partially convex spherical surfaces 11a and 12a of the inner ring seal portion 11 and the inner ring seal portion 12 may be formed.

[0051] As shown in Figure 2, the partially convex spherical surface 11a of the seal inner ring 11 and the outer peripheral surface 3b of the inner joint member 3 share a common spherical center O1. Furthermore, the partially convex spherical surface 12a of the seal middle ring 12 and the sliding surface 5b of the cage 5 share a common spherical center O2. Both spherical centers O1 and O2 are offset by an equidistant distance on opposite sides in the axial direction with respect to the joint center O.

[0052] The spherical radius SR1 of the partially convex spherical surface 11a of the inner seal ring 11 is less than or equal to the spherical radius SR3 of the outer circumferential surface 3b of the inner joint member 3 (SR1 ≤ SR3). This prevents interference between the inner seal ring 11 and the cage 5 when the constant velocity universal joint 1 takes an operating angle. The spherical radius SR2 of the partially convex spherical surface 12a of the middle seal ring 12 is less than or equal to the spherical radius SR4 of the sliding surface 5b of the cage 5 (SR2 ≤ SR4). This ensures that interference between the middle seal ring 12 and the outer joint member 2 is prevented.

[0053] As shown in Figure 1, the compression coil spring 14 is capable of pushing the seal outer ring 13 toward the opening 2a in the axial direction due to the restoring force of the spring 14. The compression coil spring 14 is positioned so that the spiral of the spring 14 follows the inner circumferential surface 10a of the cover 10. Furthermore, the compression coil spring 14 is interposed between the support surface 13d of the seal outer ring 13 and the plate 16, with its axial length shortened from its natural length.

[0054] The compression coil spring 14 pushes the outer seal ring 13 toward the opening 2a, so that regardless of whether the constant velocity universal joint 1 is operating at an angle, the outer ring seal portion 13b of the outer seal ring 13 is always pressed against the partially convex spherical surface 12a of the inner seal ring 12. Furthermore, the inner ring seal portion 12b of the inner seal ring 12 is always pressed against the partially convex spherical surface 11a of the inner seal ring 11. In this way, the sealing performance of the constant velocity universal joint 1 is ensured by the outer ring seal portion 13b and the inner ring seal portion 12b.

[0055] In the constant velocity universal joint 1 described above, even if the inner diameter of the outer seal ring 13 is enlarged to increase the maximum operating angle θ, sealing performance can be ensured without increasing the length of the partial convex spherical surfaces 11a and 12a of the inner seal ring 11 and the middle seal ring 12 in accordance with the enlargement. In other words, it is possible to avoid increasing the outer diameter of the inner seal ring 11 and the middle seal ring 12. Therefore, when the constant velocity universal joint 1 takes an operating angle, the partial convex spherical surfaces 11a and 12a of the inner seal ring 11 and the middle seal ring 12 are less likely to interfere with the outer joint member 2 or the cover 10. As a result, a higher maximum operating angle θ can be achieved. The maximum operating angle θ is, for example, about 18°. [Explanation of Symbols]

[0056] 1. Sliding type constant velocity universal joint 2. Outer joint member 2a aperture 3. Inner joint member 4 balls 6 shafts 9. Seal mechanism 10 Covers 11 Seal inner ring 11a Partially convex spherical surface 12 Seal Inner Ring 12a Partially convex sphere 12b Central ring seal section 13 Seal outer ring 13b Outer ring seal section 14 Compression coil spring O joint center O1 center of sphere O2 center of sphere

Claims

1. An outer joint member with an opening formed therein, An inner joint member housed on the inner circumference of the outer joint member in a state that allows for angular and axial displacement relative to the outer joint member, A torque transmission member that transmits torque between the outer joint member and the inner joint member, A shaft with one end attached to the inner circumference of the aforementioned inner joint member, A sliding constant velocity universal joint comprising a sealing mechanism that seals the opening of the outer joint member on the outer circumference side of the shaft extending from the inner joint member, The aforementioned sealing mechanism A cylindrical portion connected to the outer joint member, A seal outer ring is positioned along the inner circumference of the cylindrical portion and is capable of axial displacement relative to the cylindrical portion, A seal inner ring is attached to the outer circumference of the shaft extending from the inner joint member, A seal ring interposed between the seal outer ring and the seal inner ring, contacting the seal outer ring from the opening side and contacting the seal inner ring from the opposite side of the opening, The seal outer ring is provided with an elastic member that pushes the seal outer ring toward the opening along the axial direction, The inner ring of the seal has a partially convex spherical surface on its outer circumference, The seal ring has a seal portion on its inner circumference that can slide against the partially convex spherical surface of the seal ring, and has a partially convex spherical surface on its outer circumference. A sliding constant velocity universal joint characterized in that the seal outer ring has an outer ring seal portion on its inner circumference that is capable of sliding with the partially convex spherical surface of the seal inner ring.

2. The sliding constant velocity universal joint according to claim 1, characterized in that the spherical center of the partial convex spherical surface of the inner ring of the seal and the spherical center of the partial convex spherical surface of the middle ring of the seal are offset on opposite sides in the axial direction with respect to the joint center.

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