JP2013087885A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a constant velocity universal joint in which a thermoplastic elastomer boot having an outer joint member mounting section is formed in a cylindrical shape while reducing a maximum outer diameter, and which is excellent in durability and sealing property.SOLUTION: In the opening of the mouth of an outer joint member 1, a circumferential protrusion 35 and a circumferential recess 36 are formed in a large-diameter section 4a, and a small-diameter section 4b is formed to have a linear vertical sectional shape in the entire circumferential range. An intermediate member 50 is a short cylindrical body having a cylindrical outer peripheral surface. The intermediate member 50 includes a thick-walled section 50 fitted in the small-diameter section 4b and a circular arc-shaped connection section 61 which connects the thick-walled sections 60. The intermediate member 50 further includes a cutout formed at a portion corresponding to the circumferential protrusion 35 to which the circumferential protrusion is fitted.

Description

  The present invention relates to a constant velocity universal joint.

Constant velocity universal joints used in power transmission devices such as automobiles and various industrial machines are fitted with boots to prevent leakage of grease sealed inside the joints and to prevent foreign matters such as dust from entering the joints. The The boot generally has a large-diameter mounting portion attached to the opening of the outer joint member of the constant velocity universal joint, and a small-diameter mounting portion attached to a shaft connected to the inner joint member of the constant velocity universal joint. And a bent portion (bellows portion) that connects the large-diameter mounting portion and the small-diameter mounting portion.

  As a constant velocity universal joint, a fixed type constant velocity universal joint (for example, a Rzeppa type, a barfield type, etc.) that can take a large operating angle of θ = 45 to 50 deg, or an operating angle that cannot be taken so large. There are slidable constant velocity universal joints (for example, double offset type, tripod type, cross groove type, etc.) that can slide in the axial direction of the outer joint member. And as an outer joint member, there exists a cylindrical surface shape or a non-cylindrical surface shape in the outer-diameter surface shape of the opening part by which a boot is mounted | worn (fixed by external fitting).

  Such boots include resin boots (thermoplastic elastomer boots) and rubber boots (chloroprene rubber boots).

  Chloroprene rubber boots have relatively good performance as boots for constant velocity universal joints, but have aspects such as fatigue resistance, wear resistance, low temperature resistance, heat aging resistance, and grease resistance (oil resistance). Depending on the use conditions, it may not be sufficient. For this reason, it tends to be replaced by a boot made of thermoplastic elastomer having better performance.

  When the outer peripheral surface shape of the opening of the outer joint member is a non-cylindrical surface shape, the inner peripheral surface of the large-diameter mounting portion of the boot attached to the outer joint member needs to be formed into a non-cylindrical shape along the outer peripheral surface shape. There is. However, with thermoplastic elastomer boots, a non-cylindrical shape consisting of a thick portion and a thin portion requires a relatively high level of molding technology, so that the contour of the outer joint member is a non-cylindrical constant velocity universal joint. The use of is delayed compared to the cylindrical one.

  Therefore, conventionally, an interposing member (intermediate member) is externally fitted to a non-cylindrical opening, and a large-diameter mounting portion of a boot is externally fixed to the intermediate member ( Patent Documents 1 to 3).

  That is, the intermediate member is formed of a ring body in which an outer peripheral surface is a cylindrical surface, and an inner bulging portion that fits into a concave portion of a non-cylindrical shape portion of the outer joint member is formed on the inner peripheral surface. Therefore, a boot having a cylindrical large-diameter mounting portion can be used as it is by fitting (externally fitting) such an intermediate member into the opening of the outer joint member of the constant velocity universal joint. That is, the thermoplastic elastomer boot need not have a shape corresponding to the non-cylindrical opening.

JP-A-2005-240962 JP 2005-221078 A JP 2007-120580 A

  However, if the intermediate member as described above is used, the intermediate member is a ring body. Therefore, if the large-diameter mounting portion of the boot is externally fitted to such an intermediate member, the outer diameter of the mounting portion to this outer joint member The size becomes large, which inevitably increases the outermost diameter.

  Therefore, in view of such circumstances, the present invention can suppress the increase in the outermost diameter, and can use a boot made of a thermoplastic elastomer having a large-diameter mounting portion of the boot in a cylindrical shape. And a constant velocity universal joint excellent in sealing performance.

  The constant velocity universal joint according to the present invention includes an outer joint member, an inner joint member accommodated in the outer joint member, and a torque transmission member interposed between the outer joint member and the inner joint member. The joint member has a mouth portion in which the inner joint member is accommodated, and the mouth portion has a non-cylindrical shape in which a large-diameter portion and a small-diameter portion appear alternately when viewed in a cross section. A constant velocity universal joint to which a boot made of a thermoplastic polyester elastomer is fitted and fixed via an intermediate member, wherein the mouth portion opening portion of the outer joint member has a peripheral portion on the opening end side at a large diameter portion. A thick-walled portion that fits into the small-diameter portion when the intermediate member is externally fitted to the mouth portion opening portion. And fit in the circumferential recess of the large diameter part An arc-shaped connecting portion that connects adjacent thick-walled portions, and a portion corresponding to the circumferential convex portion of the large-diameter portion is formed with a notch that fits the circumferential convex portion, With the boot fitted on the intermediate member, the inner peripheral surface of the large-diameter mounting portion of the boot comes into contact with the circumferential convex portion via the notch.

  According to the constant velocity universal joint of the present invention, the intermediate member has its thick portion fitted into the small diameter portion of the outer joint member, and its arcuate connection portion fits into the circumferential recess of the large diameter portion. It can be stably mounted on the boot mounting portion (open end portion) of the mouse portion of the outer joint member. Moreover, since the outer peripheral surface of the intermediate member is a short cylindrical body having a cylindrical surface shape, the large-diameter mounting portion can be obtained by externally fitting the large-diameter mounting portion of the boot, which is a short cylindrical portion, to the intermediate member. Can be brought into close contact with the outer peripheral surface of the intermediate member. In addition, since the intermediate member has a notch for fitting the circumferential convex portion at a portion corresponding to the circumferential convex portion of the large diameter portion, the large diameter mounting portion of the boot is attached to the intermediate member. In the fitted state, the inner peripheral surface of the large-diameter mounting portion can be brought into contact with the circumferential convex portion, and in this state, the arc-shaped connecting portion is fitted in the circumferential concave portion of the large-diameter portion. . For this reason, even when the boot is mounted, the outermost diameter can be kept small.

  In a state where the intermediate member is externally fitted to the mouth portion opening, the outer diameter of the outer peripheral surface of the intermediate member is the same as the outer diameter of the circumferential protrusion of the large diameter portion or the circumferential protrusion of the large diameter portion. It can be set to be slightly larger than the outer diameter dimension. By setting in this way, the binding force can be stabilized when the large-diameter mounting portion of the boot is tightened with the boot band.

  In the state in which the intermediate member is externally fitted to the mouth portion opening, the outer diameter of the thick portion of the intermediate member may be slightly larger than the outer diameter of the arcuate connection portion of the intermediate member. By setting in this way, when the large-diameter mounting portion of the boot is tightened with the boot band, the deformation amount of the thick-walled portion becomes large, so that the binding force can be stabilized.

  Even if the inner circumferential surface of the intermediate member is provided with at least one circumferential inner ridge that presses against the bottom surface of the circumferential groove, the inner circumferential surface of the large-diameter mounting portion of the boot is provided on the outer circumferential surface of the intermediate member. There may be provided at least one circumferential outer ridge that presses against the outer circumferential surface.

  In addition, two circumferential inner ridges that are pressed against the bottom surface of the circumferential groove are provided at predetermined intervals in the axial direction on the inner circumferential surface of the intermediate member, and one circumferential outer ridge is provided on the outer circumferential surface of the intermediate member. You may provide in the site | part corresponding to the intermediate site | part of the said 2 circumferential direction internal protrusion. The circumferential inner ridge and the circumferential outer ridge are ridges continuous in the circumferential direction of the outer joint member. Furthermore, you may provide a circumferential inner convex line in the axial direction corresponding | compatible part of the circumferential convex part of the outer joint member in the inner peripheral surface of the thick part of an intermediate member. This circumferential inner convex portion is discontinuous in the circumferential direction.

  The large-diameter mounting portion of the boot is formed with a circumferential concave groove in which a boot band is mounted on the outer peripheral surface thereof, and is circumferentially bulged in an axial intermediate corresponding portion of the circumferential concave groove on the inner peripheral surface thereof. A first circumferential groove is formed between the circumferential convex portion of the outer joint member and the arc-shaped coupling portion of the intermediate member, and the first circumferential groove on the outer circumferential surface of the thick portion of the intermediate member is formed. A second circumferential groove is formed at a position corresponding to the axial direction of the one circumferential groove, and the first circumferential groove and the second circumferential groove constitute a circumferential fitting groove that is continuous in the circumferential direction. It is preferable that a circumferential bulge portion of the large-diameter mounting portion of the boot is fitted in the groove. At this time, the vertical cross-sectional shape of the outer peripheral surface of the thick portion of the intermediate member and the vertical cross-sectional shape of the outer peripheral surface of the outer circumferential member of the outer joint member or the arc-shaped connecting portion of the intermediate member seem to be substantially the same shape. Can be.

  The circumferential concave portion and the small diameter portion of the large-diameter portion of the outer joint member are joined via an edge portion, and the edge portion is connected to the arcuate connection portion and the thick-walled portion in the intermediate member with the intermediate member attached. It is preferable to bite into the boundary part.

  In the present invention, a thermoplastic elastomer boot having a cylindrical shape of the large-diameter mounting portion of the boot can be attached to the outer joint member of the constant velocity universal joint while the outermost diameter is minimized. For this reason, it is easy to improve the mounting property and positioning stability of the large-diameter mounting portion of the boot with respect to the outer joint member, and to ensure stable sealing performance. And since the boot made from a thermoplastic elastomer can be applied, durability improves compared with the boot made from a chloroprene rubber, and the reliability of boot performance improves.

It is a longitudinal cross-sectional view of the constant velocity universal joint which shows embodiment of this invention. It is a cross-sectional view of the constant velocity universal joint shown in FIG. It is a longitudinal cross-sectional view of the outer joint member of the constant velocity universal joint shown in the said FIG. It is the XX sectional view taken on the line of FIG. It is the YY sectional view taken on the line of the said FIG. The intermediate member used for the constant velocity universal joint shown in the said FIG. 1 is shown, (a) is a front view, (b) is a side view. It is a principal part expanded sectional view of the constant velocity universal joint shown in the said FIG. It is a principal part expanded sectional view of the site | part different from FIG. 7 of the constant velocity universal joint shown in the said FIG. It is a principal part expanded sectional view of the intermediate member used for the constant velocity universal joint shown in the said FIG. It is a principal part expanded sectional view of the site | part different from FIG. 9 of the intermediate member used for the constant velocity universal joint shown in the said FIG. It is a principal part expanded horizontal sectional view before mounting | wearing of the intermediate member shown in the said FIG. FIG. 2 is an enlarged cross-sectional view of a main part after the intermediate member shown in FIG. 1 is mounted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  1 and 2 show a tripod type constant velocity universal joint according to the present invention. The tripod type constant velocity universal joint includes an outer joint member 1, a tripod member 2 as an inner joint member, and a torque transmission member 3. .

  The outer joint member 1 has a cup-shaped mouth portion 4 opened at one end, and a stem portion 5 projecting from the bottom wall of the mouth portion 4, and is axially located at a three-way position in the circumferential direction of the inner circumference. An extending track groove 6 is formed. The mouse part 4 has a non-cylindrical shape in which the large diameter part 4a and the small diameter part 4b appear alternately when viewed in cross section. That is, the mouse portion 4 is formed with the large-diameter portion 4a and the small-diameter portion 4b, whereby the three track grooves 6 extending in the axial direction are formed on the inner peripheral surface thereof.

  Roller guide surfaces (roller contact surfaces) 7 and 7 are formed on the side walls of each track groove 6 facing each other in the circumferential direction. Further, the inner peripheral surface has a three-valve corollary shape in which the small inner diameter portion 12 and the large inner diameter portion 13 that appear alternately in the circumferential direction are connected by the roller guide surface 7. That is, in the outer joint member 1, the track groove 6 composed of the roller guide surface 7 facing in the circumferential direction and the large inner diameter portion 13 provided between the roller guide surfaces 7, 7 is formed at three locations on the inner periphery. Is.

  The tripod member 2 includes a boss 8 and a leg shaft 9. The boss 8 is formed with a female spline 11 coupled to the shaft 10 so as to be able to transmit torque. The leg shaft 9 protrudes in the radial direction from the circumferentially divided position of the boss 8.

  Each leg shaft 9 includes a cylindrical outer peripheral surface 14 and an annular ring groove 16 formed near the shaft end. A roller member 20 constituting the torque transmission member 3 is externally fitted to the outer periphery of the leg shaft 9 via a plurality of needle rollers 17. The cylindrical outer peripheral surface 14 of the leg shaft 9 provides the inner raceway surface of the needle roller 17. The inner peripheral surface of the roller member 20 is cylindrical and provides the outer raceway surface of the needle roller 17.

  The needle roller 17 is in contact with the outer washer 21 at the outer end face of the leg shaft 9 as viewed in the radial direction, and is in contact with the inner washer 22 at the opposite end face. Since the outer washer 21 is restricted from moving in the axial direction by the circlip 23 attached to the ring groove 16, the needle roller 17 is also restricted from moving in the axial direction.

  An end male spline 25 of the shaft (shaft member) 10 is fitted into the female spline 11 of the tripod member 2, and the female spline 11 and the end male spline 25 are fitted. Further, a retaining ring 26 for retaining is attached to the distal end portion and the proximal end portion of the end male spline 25.

  By the way, the opening of the outer joint member 1 is sealed by the boot 30. Therefore, a boot mounting portion 31 is formed on the opening side of the outer peripheral surface of the outer joint member 1 (opening portion of the mouse portion 4). Then, the boot 30 is fitted on the boot mounting portion 31 via an intermediate member 50 described later, and is tightened by the boot band 32.

  The boot 30 includes a large-diameter portion attaching portion 30a, a small-diameter attaching portion 30b, and a bellows portion (connecting portion) 30c capable of bending and expanding / contracting connecting the large-diameter attaching portion 30a and the small-diameter attaching portion 30b. The boot 30 is made of a thermoplastic polyester elastomer having a hardness of 35 or more and 50 or less according to a type D durometer defined in JIS K 6253. A thermoplastic polyester elastomer is a material having an elastic modulus intermediate between a very flexible material such as vulcanized rubber and a highly rigid material such as a thermoplastic resin. This thermoplastic polyester-based elastomer has the characteristics of both vulcanized rubber and thermoplastic resin. Even when it is deformed, it has rubber elasticity that restores its original shape, higher mechanical strength than vulcanized rubber, It is a material exhibiting characteristics such as thermoplasticity to which a molding method applied to a thermoplastic resin can be applied.

  By the way, on the outer peripheral surface of the mouth portion opening of the outer joint member 1, the large-diameter portion 4 a has a circumferential convex portion 35 on the opening end side and the circumferential convex portion 35, as shown in FIGS. 3 and 7. Also, the boot mounting portion 31 is formed by forming a circumferential recess 36 on the back side of the joint.

  In this case, as shown in FIG. 7, a chamfered portion 38 composed of a tapered surface (inclined surface) 38a and a rounded portion 38b is formed on the outer diameter side of the large diameter portion 4a, and the large diameter portion 4a. A circumferential recess 36 is formed on the outer peripheral surface of the opening end side, and a circumferential projection 35 is formed between the circumferential recess 36 and the chamfered portion 38. The circumferential recess 36 includes a bottom surface 37 having a predetermined depth, an opening-side taper portion 36b, and a joint back-side taper surface 36c. For this reason, the circumferential projection 35 has a trapezoidal longitudinal cross-sectional shape. The taper angle θ (inclination angle with respect to the joint axis) of the tapered surface 38a is preferably set to 25 ° or more and 60 ° or less, and more preferably set to 25 ° or more and 45 ° or less. Further, in the small diameter portion 4b, the entire circumferential range has a straight vertical cross section, and the cross sectional shape has an arc shape.

  The large-diameter mounting portion 30a of the boot 30 has a short cylindrical shape, and as shown in FIGS. 1 and 7, a circumferential concave groove 40 in which the boot band 32 is mounted is formed on the outer peripheral surface thereof. On the inner peripheral surface of the large-diameter mounting portion 30a, a circumferential bulging portion 42 is formed at the axially corresponding intermediate portion.

  The small-diameter mounting portion 30b of the boot 30 has a short cylindrical shape, and a circumferential groove 43 in which the boot band 32 is mounted is formed on the outer peripheral surface thereof as shown in FIG. On the inner peripheral surface of the small-diameter mounting portion 30b, a circumferential bulging portion 44 is formed at the axially corresponding intermediate portion. The small-diameter mounting portion 30 b is fitted on the boot mounting portion 45 of the shaft (shaft member) 10. The boot mounting portion 45 includes a circumferential groove 46 and circumferential ridges 47 provided at both ends of the circumferential groove 46. For this reason, if the boot band 32 is attached to the circumferential groove 43 and the boot band 32 is tightened with the small-diameter attachment portion 30b externally fitted to the boot attachment portion 45 of the shaft (shaft member) 10, The circumferential bulging portion 44 is fitted into the directional groove 46, and the circumferential ridges 47 and 47 bite into the inner diameter surface of the small diameter mounting portion 30b, so that the small diameter mounting portion 30b is fixed to the boot mounting portion 45. Is done.

  By the way, on the large-diameter attachment portion 30a side, the intermediate member 50 is fitted into the large-diameter attachment portion 30a and attached to the boot attachment portion 31 of the outer joint member 1. The intermediate member 50 can be made of resin or rubber thermoplastic elastomer. In other words, any material can be selected because it can be used even if it does not maintain performances such as fatigue, wear and low temperature required for the boot. Of course, you may select the material which can be used for boots. In addition, the intermediate member 50 may be integrally formed, or may be applied in combination with a form divided in the circumferential direction. For example, when the intermediate member 50 is mounted on the boot mounting portion 31 of the outer joint member 1 and a material that cannot be deformed for mounting is selected, the intermediate member 50 divided in the circumferential direction is applied. Good.

  As shown in FIG. 6, the intermediate member 50 includes a ring portion 50 a including a thin arc-shaped connecting portion 61 and protrusions 50 b disposed at a 120 ° pitch along the circumferential direction. In this case, the taper part 51a is formed in one axial direction edge part of the ring part 50a, and the said protrusion part 50b is provided in a row by this axial direction end surface. The projecting portion 50b has an inner circumferential surface that has an arc shape that fits into the small-diameter portion 4b of the outer joint member 1, and an outer circumferential surface that includes the first tapered arc portion 52a on the outer end side and the first tapered arc. A first arcuate surface part 52b provided continuously with the part 52a, a second taper arcuate part 52c on the opposite side of the first taper arcuate part 52a via the first arcuate surface part 52b, the second taper arcuate part 52c and the taper. A second arcuate surface part 52d between the part 51a and the part 51a is formed. Further, a rounded portion 52e (see FIG. 8 and the like) is formed at a corner portion between the first tapered arc portion 52a and the outer end surface of the protruding portion 50b.

  When the intermediate member 50 configured as described above is mounted (externally fitted) to the boot mounting portion 31 of the outer joint member 1, each protruding portion 50b is fitted to each small diameter portion 4b. Further, as shown in FIG. 7, in the large diameter portion 4 a, the arc-shaped connecting portion 61 of the ring portion 50 a is fitted into the circumferential recess 36. At this time, the arc-shaped connecting portion 61 of the ring portion 50a is formed with a tapered portion 51b at the other axial end, as shown in FIG. 7, and this tapered portion 51b is a tapered surface 36c of the circumferential recess 36. Close to. In addition, a circumferential groove 53 is formed between the arc-shaped connecting portion 61 of the ring portion 50 a and the circumferential convex portion 35. That is, the circumferential groove 53 is formed by the tapered portion 36b, the bottom surface 37, and the tapered portion 51a.

  In the state where the intermediate member 50 is mounted on the boot mounting portion 31 of the outer joint member 1, the small diameter portion 4b includes a second tapered arc portion 52c, a second arc surface portion 52d, and a tapered portion 51a as shown in FIG. Thus, the circumferential groove 54 is formed. The circumferential groove 54 and the circumferential groove 53 constitute a circumferential fitting groove 55 that is continuous in the circumferential direction. As described above, the intermediate member 50 includes the protruding portion 50b and a part of the ring portion 50a corresponding to the axial direction, and the intermediate member 50 is fitted to the small diameter portion 4b when the intermediate member 50 is externally fitted to the mouth portion opening. A portion 60 is formed. In addition, between the thick portions 60 in the ring portion 50a, an arcuate connecting portion 61 is formed which is fitted in the circumferential recess 36 of the large diameter portion 4a and connects the thick portions adjacent in the circumferential direction. . For this reason, there is no member on the joint opening side between the protrusions 50b adjacent in the circumferential direction. In a state in which the intermediate member 50 is mounted on the boot mounting portion 31 of the outer joint member 1, a notch 62 in which the circumferential convex portion 35 of the outer joint member 1 is fitted is provided.

  In this case, the vertical cross-sectional shape of the outer peripheral surface of the thick portion 60 of the intermediate member 50 and the vertical cross-sectional shape of the outer peripheral surface where the arc-shaped connecting portion 61 of the intermediate member 50 continues are substantially the same shape. It can be set to be.

  If the large-diameter mounting portion 30a of the boot 30 is externally fitted to the intermediate member 50 in a state where the thus configured intermediate member 50 is mounted on the boot mounting portion 31 of the outer joint member 1, the large-diameter mounting portion The circumferential bulging portion 42 of 30 a is fitted into a circumferential fitting groove 55 constituted by a circumferential groove 53 and a circumferential groove 54.

  In this case, in the state where the intermediate member 50 is externally fitted to the mouth portion opening, the outer diameter dimension D1 (see FIG. 5) of the outer peripheral surface of the intermediate member 50 is the outer diameter dimension of the circumferential convex portion 35 of the large-diameter mounting portion 4a. It is the same as D2 (see FIG. 7) or is set to be slightly larger than the outer diameter D2 of the circumferential convex portion 35 of the large-diameter portion 4a. In this case, the outer diameter D3 (see FIG. 5) of the thick portion 60 of the intermediate member 50 and the outer diameter D4 (see FIG. 5) of the arc-shaped connecting portion 61 of the intermediate member 50 are set to be the same.

  Further, in the state in which the intermediate member 50 is externally fitted to the mouth portion opening, the outer diameter dimension D3 of the thick portion 60 of the intermediate member 50 is slightly smaller than the outer diameter dimension D4 of the arc-shaped connecting portion 61 of the intermediate member 50. You may set so that it may be large.

  In a state in which the large-diameter mounting portion 30a of the boot 30 is externally fitted, the inner peripheral surface of the large-diameter mounting portion 30a and the outer peripheral surface of the arc-shaped connecting portion 61 of the intermediate member 50 are in direct contact. Therefore, in this state, when the boot band 32 is tightened (reduced in diameter) in the circumferential concave groove 40 on the outer peripheral surface of the large-diameter mounting portion 30 a, the circumferential bulge portion 42 is fixed to the circumferential fitting groove 55. At the same time, the inner peripheral surface of the large-diameter mounting portion 30 a is in close contact (pressure contact) with the outer peripheral surface of the arc-shaped connecting portion 61 of the intermediate member 50. For this reason, the large-diameter mounting portion 30 a of the boot 30 is fixed in a stable state to the boot mounting portion 31 of the outer joint member 1 via the intermediate member 50.

  Since the outer joint member 1 is made of metal such as iron, and the intermediate member 50 is made of resin, rubber, thermoplastic elastomer, or the like, the deformation amount of the intermediate member 50 is increased. For this reason, when the boot 30 is mounted and fixed with a fastening member such as the boot band 32, the outer diameter D1 of the outer peripheral surface of the intermediate member 50 is equal to the outer diameter D2 of the circumferential convex portion 35 of the large diameter portion 4a. It was set to be slightly larger than the outer diameter D2 of the circumferential convex portion 35 of the same or large diameter portion 4a. That is, the outer diameter of the outer peripheral surface of the intermediate member 50 is preferably 1 to 1.02 times the outer diameter of the circumferential protrusion 35 of the outer joint member 1.

  In addition, the thick portion 60 has a larger deformation amount when the boot 30 is mounted and fixed with a fastening member such as the boot band 32 than the arcuate connection portion 61 of the intermediate member 50. Accordingly, the binding force is kept uniform by making the outer diameter D3 slightly larger than the outer diameter D4. Accordingly, the outer shape of the intermediate member 50 in this case is not a perfect circle but a substantially cylindrical shape such as a mussel shape. The outer diameter (maximum) of the thick part 60 is preferably 1 to 1.05 times the outer diameter of the arcuate connecting part 61. If it exceeds 1.05 times, non-uniformity of the binding force applied to the arc-shaped connecting part 61 and the thick part 60 occurs. The outer shape of the thick portion 60 may be a cylinder, or may be a convex shape with a thick central portion and thin end portions (joined portions with the arc-shaped connecting portion 61).

  According to the constant velocity universal joint of the present invention, the intermediate member 50 has a thick-walled portion 60 fitted into the small-diameter portion 4b of the outer joint member 1, and an arc-shaped connecting portion 61 formed in the circumferential recess of the large-diameter portion 4a. Since it fits in 36, it can mount | wear to the boot mounting part (opening edge part) 31 of the mouse | mouth part 4 of the outer joint member 1 stably. Moreover, since the outer peripheral surface of the intermediate member 50 is a short cylindrical body having a cylindrical surface shape, by fitting the large-diameter mounting portion 30a of the boot 30 that is a short cylindrical portion to the intermediate member 50, The inner peripheral surface of the large-diameter mounting portion 30a and the outer peripheral surface of the intermediate member 50 can be brought into close contact with each other. In addition, the intermediate member 50 is provided with a notch 62 in which the circumferential convex portion 35 is fitted at a portion corresponding to the circumferential convex portion 35 of the large-diameter portion 4a. In the state where the large-diameter mounting portion 30a is externally fitted, the inner peripheral surface of the large-diameter mounting portion 30a of the boot 30 can be brought into contact with the circumferential convex portion 35. Further, in this state, the arc-shaped connecting portion 61 Is fitted in the circumferential recess 36 of the large diameter portion 4a. For this reason, even when the boot 30 is mounted, the maximum outer diameter can be kept small.

  Thus, in the present invention, the outermost diameter is minimized and the thermoplastic elastomer boot 30 having the cylindrical shape of the large-diameter mounting portion 30a is attached to the outer joint member 1 of the constant velocity universal joint. Can do. For this reason, it is easy to improve the mounting property and positioning stability of the large-diameter mounting portion 30a of the boot 30 with respect to the outer joint member 1, and to ensure a stable sealing property. Since the thermoplastic elastomer boot 30 can be applied, the durability is improved as compared with the chloroprene rubber boot and the reliability of the boot performance is improved. In particular, by using a thermoplastic polyester elastomer having a hardness of 35 or more and 50 or less according to JIS K6253 as a boot material, the boot 30 has fatigue, wear and high speed rotation ( It can be used for a long time with a stable function as the boot 30. In addition, when the hardness by the type D durometer prescribed in JIS K6253 is less than 35 or more than 50, the fatigue and wear properties are not so excellent.

  Since the circumferential bulging portion 42 of the large-diameter mounting portion 30a is fitted into the circumferential fitting groove 55 constituted by the circumferential groove 53 and the circumferential groove 54, a stable mounting state can be maintained. When rotating, the attached boot is difficult to come off, preventing leakage of grease enclosed in the joint and preventing foreign matter such as dust from entering the joint.

  Since the tapered surface 38a is formed at the end of the mouth portion opening of the outer joint member 1, the turning joint efficiency of the outer joint member 1 is improved and the outer joint member of the large-diameter mounting portion 30a of the boot 30 is improved. It is possible to improve the mountability of the first boot mounting portion 31. In this case, when the taper angle θ of the taper surface 38a exceeds 60 °, the boot mounting property is hindered. When the taper angle θ is less than 25 °, the axial length of the outer joint member 1 becomes large, and space efficiency and strength are increased. Not preferable.

  By the way, in the intermediate member 50, as shown in FIGS. 9 and 10, a pair of circumferential inner ridges 65, 66 may be provided on the inner circumferential surface over the entire circumferential direction. In this case, each of the circumferential inner ridges 65 and 66 has a triangular cross section. Further, on the inner peripheral surface of the thick portion 60, arc-shaped circumferential inner ridges 67 different from the circumferential inner ridges 65, 66 may be provided. The circumferential inner protrusion 67 also has a triangular cross section.

  Moreover, you may make it provide the circumferential direction outer protruding item | line 70 in the outer peripheral surface of the intermediate member 50 over the circumferential direction perimeter. Further, an arcuate outer circumferential ridge 71 having an arc shape different from the circumferential outer ridge 70 may be provided on the outer circumferential surface of the thick portion 60. It is preferable to provide the circumferential outer ridge 70 at a position corresponding to an intermediate portion between the circumferential inner ridges 65 and 66. By providing in this way, the intermediate member 50 exhibits stable adhesion on the outer peripheral side and the inner peripheral side. In this embodiment, the outer circumferential ridges 70 and 71 have a triangular cross section.

  As described above, when the circumferential inner ridges 65, 66, 67 and the like are provided, the circumferential inner ridges 65, 66, 67 become crushed when they are mounted, and the intermediate member 50 and the outer joint member 1 The sealing performance between the two is improved. Further, when the circumferential outer ridges 70 and 71 are provided, the circumferential outer ridges 70 and 71 are crushed when mounted, and between the intermediate member 50 and the large-diameter mounting portion 30 a of the boot 30. Improves the sealing performance. The circumferential inner ridge 67 is preferably provided at a position corresponding to the circumferential projection 35 of the outer joint member 1. By setting in this way, the tight binding force when the boot band 32 is fastened is reduced. Uniformity can be prevented.

  The circumferential inner ridges 65, 66, 67 and the outer circumferential ridges 70, 71 are not limited to a triangular shape in cross section, and may have various shapes such as a semicircle, a semi-ellipse, and a rectangle. Things can be adopted. In this case, it is preferable that the cross-sectional shape is a triangular shape as shown in the figure by considering the sealing property.

  The height T (see FIGS. 11 and 12) of the circumferential inner ridges 65, 66, 67 and the circumferential outer ridges 70, 71 is preferably 0.3 mm or more and 1 mm or less. If it is less than 0.3 mm, it is difficult to obtain the effect of this ridge (seal improvement effect), and if it exceeds 1 mm, the adhesion to the mating surface is reduced or the binding force is uneven when the boot band 32 is fastened. Is more likely to occur.

  Further, as shown in FIG. 11, the circumferential inner ridges 65 and 66 corresponding to the circumferential recess 36 of the outer joint member 1 are formed at the joint portion between the arc-shaped connecting portion 61 and the thick portion 60 of the intermediate member 50. A concave arc-shaped portion 75 is formed. A boundary portion (a boundary portion corresponding to the concave arc-shaped portion) between the large diameter portion 4 a and the small diameter portion 4 b of the outer joint member 1 is an edge portion 76.

  For this reason, when the intermediate member 50 is attached to the outer joint member 1, as shown in FIG. 12, the boundary portion (edge portion) 76 of the outer joint member 1 bites into the concave arc-shaped portion 75 of the intermediate member 50. become. Thereby, an improvement in sealing performance can be achieved. If the radius of curvature (R dimension) of the concave arcuate portion 75 of the intermediate member 50 is too large, a space is created by the central portion of the concave member 75 and the sealing performance is lowered. On the other hand, if the radius of curvature (R dimension) is too small, the biting property of the edge portion 76 is lowered. For this reason, this radius of curvature (R dimension) is preferably about R0.5 mm to R5 mm.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to the above-described embodiments, and various modifications are possible. For example, the circumferential inner ridges 65, 66, 67 and the circumferential directions When the outer ridges 70 and 71 are provided, the cross-sectional shape is not limited to a triangular shape, and various shapes such as a semicircle, a semi-ellipse, and a rectangle can be employed. However, considering the sealing property, the cross-sectional shape is preferably a triangular shape as shown in the figure. Moreover, when setting it as a triangular shape, it may be a regular triangle or an isosceles triangle. The numbers of the circumferential inner ridges 65, 66, 67 and the circumferential outer ridges 70, 71 are not limited to those in the illustrated example, and can be arbitrarily set.

  The constant velocity universal joint is a single roller type tripod type constant velocity universal joint in the above embodiment, but may be a double roller type tripod type constant velocity universal joint. Further, it may be a sliding type constant velocity universal joint other than the tripod type constant velocity universal joint, or may be a fixed type constant velocity universal joint.

1 Outer joint member 2 Tripod member (inner joint member)
3 Torque transmitting member 4 Mouse portion 4b Small diameter portion 4a Large diameter portion 10 Shaft 12 Small inner diameter portion 13 Large inner diameter portion 30 Boot 31 Boot mounting portion 32 Boot band (tightening band)
35 circumferential convex portion 36 circumferential concave portion 40 circumferential concave groove 53, 54 circumferential groove 55 circumferential fitting groove 60 thick portion 61 arc-shaped coupling portion (thin coupling portion)
62 Notch 65, 66 Circumferential inner ridge 67 Circumferential inner ridge 70, 71 Circumferential outer ridge 75 Concave arc-shaped part (boundary part)
76 Edge

Claims (9)

An outer joint member, an inner joint member accommodated in the outer joint member, and a torque transmission member interposed between the outer joint member and the inner joint member. The mouse part has a non-cylindrical shape in which a large-diameter part and a small-diameter part appear alternately when viewed in a cross section, and the thermoplastic polyester is inserted through an intermediate member at the mouth part opening part. A constant velocity universal joint to which a boot made of an elastomer is fitted and fixed,
In the mouth portion opening of the outer joint member, in the large-diameter portion, a circumferential convex portion on the opening end side and a circumferential concave portion on the joint deeper side than the circumferential convex portion are formed, and the intermediate member is An arcuate shape that connects a thick portion that fits into the small diameter portion and a thick portion adjacent to the circumferential direction by fitting into the circumferential concave portion of the large diameter portion when externally fitted to the mouth portion opening. In a state where a notch portion into which the circumferential convex portion is fitted is formed at a portion corresponding to the circumferential convex portion of the large diameter portion, and the boot is externally fitted to the intermediate member. The constant velocity universal joint, wherein an inner peripheral surface of the outer joint member mounting portion of the boot is in contact with the circumferential convex portion of the outer joint member through the notch portion.   In a state where the intermediate member is externally fitted to the mouth portion opening, the outer diameter of the outer peripheral surface of the intermediate member is the same as the outer diameter of the circumferential protrusion of the large diameter portion or the circumferential protrusion of the large diameter portion. The constant velocity universal joint according to claim 1, wherein the constant velocity universal joint is slightly larger than an outer diameter of the joint.   The outer diameter dimension of the thick part of the intermediate member is slightly larger than the outer diameter dimension of the arc-shaped connecting portion of the intermediate member in a state in which the intermediate member is externally fitted to the mouth portion opening. The constant velocity universal joint according to claim 1.   The constant velocity according to any one of claims 1 to 3, wherein at least one circumferential inner ridge that presses against a bottom surface of the circumferential groove is provided on an inner circumferential surface of the intermediate member. Universal joint.   5. The outer circumferential surface of the intermediate member is provided with at least one circumferential outer ridge that presses against the inner circumferential surface of the outer joint member mounting portion of the boot. 6. Constant velocity universal joint.   Two circumferential inner ridges that press against the bottom surface of the circumferential groove are provided on the inner circumferential surface of the intermediate member at predetermined intervals in the axial direction, and one circumferential outer ridge is disposed on the outer circumferential surface of the intermediate member. The constant velocity universal joint according to any one of claims 1 to 3, wherein the constant velocity universal joint is provided at a portion corresponding to an intermediate portion of the two inner circumferential ridges.   The circumferential inner ridge is provided in the axially corresponding portion of the circumferential convex portion on the inner circumferential surface of the thick portion of the intermediate member, or the like according to any one of claims 1 to 6, etc. Fast universal joint. The outer joint member mounting portion of the boot is formed with a circumferential groove in which a tightening band is mounted on the outer circumferential surface thereof, and in the circumferential direction on the axial intermediate corresponding portion of the circumferential groove on the inner circumferential surface thereof. A bulge is formed,
A first circumferential groove is formed between the circumferential convex portion on the outer joint member side and the arc-shaped coupling portion of the intermediate member, and the first circumferential groove on the outer peripheral surface of the thick portion of the intermediate member A second circumferential groove is formed at a position corresponding to the axial direction of the first circumferential groove, and the first circumferential groove and the second circumferential groove constitute a circumferential fitting groove that is continuous in the circumferential direction. The constant velocity universal joint according to any one of claims 1 to 7, wherein a circumferential bulge portion of the outer joint member mounting portion is fitted.   The circumferential concave portion and the small diameter portion of the large-diameter portion of the outer joint member are joined via an edge portion, and the edge portion is connected to the arcuate connection portion and the thick-walled portion in the intermediate member with the intermediate member attached. The constant velocity universal joint according to any one of claims 1 to 8, wherein the constant velocity universal joint is bitten into a boundary portion between the constant velocity universal joint and the constant velocity universal joint.

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