JP2006266412A - Constant velocity universal joint and boots for constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability of boots 10 made of thermoplastic elastomer for a constant velocity universal joint by preventing deformation of a small diameter rising part of the boots or reducing degree of its deformation as much as possible. <P>SOLUTION: The boots 10 have a large diameter mounting part 12 mounted on an outer side joint member 2, a small diameter mounting part 14 mounted on a second rotary shaft, and a bellows part 16 for connecting the large diameter mounting part 12 and the small diameter mounting part 14 mutually. An outer peripheral face of the large diameter mounting part 12 has a cylindrical shape, and an inner peripheral face has a non-cylindrical shape along a profile of a boot mounting part of the outer side joint member 2. The whole capacity of the large diameter mounting part 12 is filled with a boot material. Wall thickness of the small diameter rising part from at least the small diameter mounting part 14 to a first adjacent crest m<SB>1</SB>is larger than that of the other parts. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint and a constant velocity universal joint boot used in power transmission systems of automobiles and various industrial machines.

  Constant velocity universal joints for automobiles and the like are used with boots attached for the purpose of preventing leakage of grease sealed inside and entry of foreign matter from the outside. This boot has a large-diameter mounting portion attached to the boot mounting portion provided at the end of the outer joint member of the constant velocity universal joint, and a boot mounting portion provided on the second rotating shaft connected to the constant velocity universal joint. And a bellows-like portion between the two attachment portions and connecting the two attachment portions. As materials for constant velocity universal joint boots, rubbers such as chloroprene and thermoplastic elastomers are widely used.

On the other hand, for 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. There is a sliding type constant velocity universal joint (for example, a double offset type, a tripod type, a cross groove type, etc.) having a mechanism that slides in the axial direction of the outer joint member. Some of the outer joint members of the constant velocity universal joint have a cylindrical shape in the opening and a non-cylindrical shape. From the viewpoint of weight reduction and workability of the constant velocity universal joint, there are many cases where it is more efficient to use a non-cylindrical shape considering the internal structure. Chloroprene rubber boots have been mainly used as constant velocity universal joint boots applied to such non-cylindrical outer joint members. Recently, the use of boots made of thermoplastic elastomer has been studied (see Patent Documents 1 to 5).
Japanese Patent Laid-Open No. 10-110738 Japanese Patent Laid-Open No. 10-196673 JP 2002-13546 A JP 2003-194093 A JP 2003-329057 A

  Constant velocity universal joint boots tend to replace chloroprene rubber boots with thermoplastic elastomer boots. However, chloroprene rubber boots are mainly used for constant velocity universal joints whose outer joint members have a non-cylindrical shape. This is because the boot made of thermoplastic elastomer is molded into a non-cylindrical shape in which the thick-walled part and the thin-walled part appear alternately in the circumferential direction, or in a complicated shape including the axial direction. This is because it is difficult. Alternatively, the thermoplastic elastomer is slightly poor in elasticity and high in material hardness in terms of material characteristics, so that it may be difficult to attach to the outer joint member or the sealing performance may be insufficient.

  When attaching the thermoplastic elastomer boot to the non-cylindrical outer joint member, between the non-cylindrical outer joint member and the large-diameter mounting portion of the cylindrical boot, or the non-cylindrical outer side A large-diameter mounting portion of the boot is formed into a non-cylindrical shape along the outer joint member with respect to the joint member, and an intermediate member (bushing) is interposed between the outer surface of the large-diameter mounting portion of the boot and the band. Conceivable. However, in this embodiment, the number of parts increases, which is not preferable in terms of management and assembly process. In addition, the cost increases. Alternatively, since the bushing requires a certain thickness, the outer diameter of the joint becomes large. Furthermore, the sealing performance at the contact portion between the outer joint member / boot and between the boot / bushing is insufficient.

  Although the large-diameter mounting portion of the boot is formed into a shape along the non-cylindrical outer joint member with a substantially constant thickness, the boot outer surface may be tightened with a band shaped along the non-cylindrical shape. Since the band has a complicated shape, the cost increases and the sealing performance is insufficient.

  In addition, the shape of the inner surface of the large-diameter mounting portion of the boot is a shape along the outer joint member having a non-cylindrical shape, and the outer surface of the large-diameter mounting portion of the boot is a cylindrical boot, and a thickened portion is provided in the thick wall portion. Although a thermoplastic elastomer boot having a different shape has been proposed (see, for example, FIG. 2 of Patent Document 5), there is a problem that sufficient sealing performance cannot be obtained with this shape.

  On the other hand, the tripod type constant velocity universal joint, which is a typical example of a constant velocity universal joint whose outer joint member has a non-cylindrical shape, is often used on the differential side of the drive shaft, and is affected by heat from the exhaust pipe, etc. There is a high possibility of receiving. In addition, since it is a sliding constant velocity universal joint, the amount of contraction / extension of the bellows is large. Due to this sliding and thermal influence, the boot made of thermoplastic elastomer requires a higher level of sealing performance, so the above-mentioned corresponding example is not sufficient.

  Also, with regard to boot durability, the stress distribution of the bellows is biased due to deformation, and the deformation from the small diameter mounting portion to the adjacent bellows portion, that is, the deformation of the small diameter rising portion becomes large, thereby reducing the boot life. There is. Alternatively, since it is thermoplastic, it has the property of softening at high temperatures, and if it undergoes deformation while being exposed to a high temperature of a certain temperature or more, it may leave a permanent deformation in its original shape and affect the boot life.

  The main object of the present invention is to improve the durability of the boot by preventing or minimizing the deformation of the small diameter rising portion of the thermoplastic elastomer boot for the constant velocity universal joint.

  The constant velocity universal joint of the present invention is a constant velocity universal joint that connects a first rotary shaft and a second rotary shaft, and an outer joint member that is coupled to the first rotary shaft so as to be able to transmit torque, Between the outer joint member and the second rotary shaft, the inner joint member coupled so as to be able to transmit torque, the torque transmission member interposed between the outer joint member and the inner joint member, and the second rotational shaft. A boot made of thermoplastic elastomer for preventing leakage of grease filled in the joint and entry of foreign matter from the outside, and the boot mounting portion of the outer joint member has a non-cylindrical outer peripheral surface. The boot includes a large-diameter attachment portion attached to the outer joint member, a small-diameter attachment portion attached to the second rotating shaft, and a bellows portion connecting the large-diameter attachment portion and the small-diameter attachment portion. The outer peripheral surface of the diameter mounting part is cylindrical and the inner peripheral surface is the outer joint. Non-cylindrical shape along the contour of the boot mounting part of the member, the entire volume of the large diameter mounting part is filled with the boot material, and at least the small diameter rising part from the small diameter mounting part to the adjacent first mountain is the other It is characterized by being thicker than the part.

  Here, the bellows part is composed of peaks and valleys that appear alternately, but from the small-diameter mounting part to the large-diameter mounting part, call it the first mountain, the first valley, the second mountain, and the second valley. And

  According to the present invention, when the boot is compressed in the axial direction by making at least the small-diameter rising portion of the boot thicker than other portions, the first mountain adjacent to the small-diameter mounting portion and the second adjacent next The stress is evenly distributed in the bellows part excluding Ichiya. As a result, the warping deformation as in the conventional case does not occur in any movable range of the constant velocity universal joint. Therefore, in combination with being made of a thermoplastic elastomer, the durability of the boot is improved.

  That is, by increasing the rigidity of at least the small-diameter rising portion of the boot, that is, the portion extending from the small-diameter mounting portion to the adjacent first mountain, it becomes difficult to deform even when stress is applied. By applying such a boot made of thermoplastic elastomer, it becomes possible to prevent a decrease in boot durability due to a change in internal pressure of the constant velocity universal joint or deformation caused by a high temperature. Since all the large-diameter mounting parts are filled with material, sufficient sealing performance can be secured. Therefore, the reliability of boot performance is improved. In addition, since the number of parts is not increased, the cost can be reduced. For example, a sliding type constant velocity universal joint used on the differential side of a drive shaft for an automobile is exposed to a high temperature atmosphere due to heat radiation from an exhaust pipe. The effect is particularly remarkable.

  Hereinafter, an embodiment will be described by taking as an example a case where it is applied to a tripod type constant velocity universal joint provided with a boot made of a thermoplastic elastomer.

  First, as shown in FIGS. 1 and 2, the tripod type constant velocity universal joint 1 includes an outer joint member 2, a tripod member 4 as an inner joint member, and a roller 6 as a torque transmission member as main components. In addition, a boot 10 is provided.

  In the illustrated embodiment, the outer joint member 2 includes a mouth portion 22 and a stem portion 26 that are integrally formed. The stem portion 26 is coupled to a first rotating shaft (not shown) by a spline shaft 28 formed at the end portion so that torque can be transmitted. The mouse portion 22 has a cup shape opened at one end, and a track groove 24 extending in the axial direction is formed at a position of the inner circumference in three equal parts. The outer peripheral surface of the mouse portion 22 has a non-cylindrical shape in which the large-diameter portions 22a and the small-diameter portions 22b appear alternately when viewed in cross section (FIG. 2). In this embodiment, the large-diameter portion 22 a is a convex arc-shaped portion corresponding to the track groove 24, and the small-diameter portion is a concave arc-shaped portion corresponding to a portion between the adjacent track grooves 24.

  The tripod member 4 includes a boss 42 and a leg shaft 46. The boss 42 is formed with a spline hole 44 that is coupled to the second rotary shaft 3 so that torque can be transmitted. The leg shaft 46 projects in the radial direction from the circumferentially divided position of the boss 42. Each leg shaft 46 of the tripod member 4 carries a roller 6. A plurality of needle rollers 8 are interposed between the leg shaft 46 and the roller 6, and the roller 6 is rotatable about the axis of the leg shaft 46. In FIG. 1, a retaining ring and a washer for preventing the roller 6 from falling off are omitted. Further, here, a structure in which one roller 6 is mounted on one leg shaft 46 is illustrated, but a structure having two rollers may be used.

  FIG. 3 shows a longitudinal section of the large diameter portion 22a of the mouse portion 22. As shown in FIG. As shown in the drawing, a boot groove 30 extending in the circumferential direction is formed in the vicinity of the end portion. The vicinity of the boot groove 30 is referred to as a boot mounting portion of the outer joint member. The bottom surface of the boot groove 30 has a partial cylindrical shape, and is a straight line parallel to the axis in the longitudinal section. A protruding portion 32 is formed over part or all of the circumferential direction of the large diameter portion 22a. The protrusion 32 is preferably located near the end surface 38 of the outer joint member 2.

  In the case of the illustrated embodiment, both sides of the protrusion 32 in the axial direction are inclined surfaces 34 and 36. The inclination angles of the inclined surfaces 34 and 36 with respect to the axis are 25 ° or more and 60 ° or less, preferably 25 ° or more and 45 ° or less. Thereby, the turning efficiency of the outer joint member 2 is improved, and at the same time, the mounting property when the large-diameter mounting portion 12 of the boot 10 is fitted to the outer joint member 2 is improved, and the outer joint member 2 after the boot is mounted. It is also possible to improve the action of preventing the boot 10 from coming off and the position stability.

  If the angle of the first inclined surface, that is, the inclined surface 34 opposite to the end surface 38 of the outer joint member 2 is larger than 60 °, the workability of the boot mounting portion of the outer joint member 2 is deteriorated. On the other hand, when the angle is less than 25 °, the action of preventing the boot 10 from coming off in the axial direction after being fitted to the outer joint member 2 and the position stability are lowered. Moreover, since it becomes a protrusion long in an axial direction, the full width of the boot attachment part of the outer joint member 2 will become large, and it is unpreferable on space efficiency or intensity | strength. When the angle of the second inclined surface, that is, the inclined surface 36 on the end surface 38 side of the outer joint member 2 is larger than 60 °, the boot mounting property is hindered. On the other hand, when the angle is less than 25 °, the protrusion 32 is elongated in the axial direction, so that the entire width of the boot mounting portion is increased, which is not preferable in terms of space efficiency and strength.

  The boot 10 is made of a thermoplastic elastomer, and every part is filled with the thermoplastic elastomer, and there are no voids. In particular, if there is a gap in the attachment portion, the tightening force of the band 13 (see FIG. 1) is not sufficiently transmitted to the boot attachment portion of the outer joint member 2, and the sealing performance is impaired. Examples of materials that can be employed include thermoplastic polyester elastomers having a type D durometer hardness of 35 to 50 in accordance with JIS K 6253. A rubber material having a type A durometer hardness of 50 or more and 70 or less according to JIS K 6253, such as chloroprene, is effective, but a type D durometer hardness according to JIS K 6253 is shown as 35 or more and 50 or less. In the case of a material having a high material hardness such as a thermoplastic polyester elastomer, the effect can be exhibited more.

As shown in FIG. 4, the overall appearance of the boot 10 has a truncated cone shape, and includes a large-diameter attachment portion 12, a small-diameter attachment portion 14, and a bellows portion 16 therebetween. In addition, the name of the mountain valley of the bellows portion 16 is the first mountain m ₁ , the first valley n ₁ , the second mountain m ₂ , and the second valley n _{2 in} order from the small diameter attachment portion 14 to the large diameter attachment portion 12. , We call it the third mountain m ₃ etc. The large-diameter mounting portion 12 is fitted to the outer joint member 2, and the small-diameter mounting portion 14 is fitted to the second rotating shaft 3 (FIG. 1), and is fastened and fixed by the boot bands 13 and 15, respectively. It has become. For this reason, the band groove 18 for receiving the boot bands 13 and 15 is formed in the outer periphery of each attaching part. The bottom surface of the band groove 18 has a cylindrical surface shape, and the longitudinal section is parallel to the axis.

  In addition to the mountability of the boot 10 to the outer joint member 2, the mountability of the bands 13, 15 to the boot 10 is an important factor to be considered in assembling the constant velocity universal joint. For example, both side walls of the band groove 18 may be continuously provided on the entire circumference, but in that case, the band mounting property may be lowered. Therefore, among the side walls of the band groove 18, in particular, the protrusion 19 that forms the side wall on the end face side that appears on the right side in FIG. 4 has no problem in the mountability of the band 13 and the position of the band 13 is stable. As the setting to be performed, the following configuration is preferable. That is, as can be seen from FIG. 5, the protrusions 19 are intermittently arranged in the circumferential direction, for example, at three equal positions, and the height of each protrusion 19 is 0.6 mm or more and 1.2 mm or less, and the axial dimension. Is 0.6 mm to 2.0 mm and the circumferential dimension is in the range of 10 ° to 25 ° from the boot axis.

  As shown in FIG. 5, the inner peripheral surface of the large-diameter mounting portion of the boot 10 has a shape that follows the outer peripheral surface shape of the mouth portion 22 of the outer joint member 2. That is, the thin part 12a corresponding to the large diameter part 22a of the mouse part 22 and the thick part 12b corresponding to the small diameter part 22b appear alternately.

  As shown in FIG. 6, the inner peripheral surface of the thin portion 12a of the large-diameter mounting portion 12 includes a chamfered portion A from the end surface side, a straight portion B parallel to the axis, a recess C, and a shoulder pad D as shown in FIG. It is formed continuously.

  The chamfered portion A is provided at least 1 mm from the end surface at an angle of 20 ° to 60 ° with respect to the axis. By providing such a chamfered portion A, the above-described boot mounting property can be further improved. The end surface side diameter of the chamfered portion A is set larger than the minimum diameter of the end surface side inclined surface 36 of the protruding portion 32 of the outer joint member 2. The meeting part of the end surface side slope 36 and the end surface 38 of the protrusion 32 of the outer joint member 2 is rounded and smoothly connected. Thus, when the boot 10 is mounted, the chamfered portion A of the boot 10 is guided by the rounded portion, so that the boot 10 can be mounted more smoothly.

The recess C has slopes C ₁ and C ₂ that contact the slopes 34 and 36 of the protrusion 32 in order to receive the protrusion 32 of the outer joint member 2. Assuming that these are the third slope C ₁ and the fourth slope C ₂ , the third slope C ₁ corresponds to the first slope 34 of the protrusion 32, and the fourth slope C 2 is the second slope of the protrusion 32. Corresponds to the slope 36. Since it is such a structure, the hollow C fits with the protrusion part 32 of the outer joint member 2, and generates the removal | prevention action to an axial direction.

  The large-diameter attachment portion 12 of the boot 10 is required to be easily attached to the boot attachment portion of the outer joint member 2 and exhibit a sufficient sealing property when tightened with the band 13. Therefore, the recess C provided on the inner surface of the large-diameter mounting portion 12 of the boot 10 has a shape along the protruding portion 32 of the outer joint member 2.

  The contour of the portion of the boot 10 from the recess C to the shoulder pad D substantially matches the contour of the portion of the outer joint member 2 from the protruding portion 32 to the end surface 38. The shoulder rest D abuts against the end face 38 of the outer joint member 2 and serves to stabilize the axial position of the boot 10.

  A shoulder 17 that connects the large-diameter mounting portion 12 and the bellows portion 16 is formed thicker than the thickness of the bellows portion 16 or the large-diameter mounting portion 12. Here, the shoulder portion 17 refers to a portion from the end surface 18 a on the bellows portion 16 side of the band groove 18 provided in the large-diameter mounting portion 12 of the boot 10 to the inclined surface 17 a connected to the final valley 16 a of the bellows portion 16. It is preferable that the thinnest wall thickness of the shoulder portion 17 is not less than twice the wall thickness of the hollow C portion which is the thinnest wall portion in the large-diameter mounting portion 12. Such a configuration is more effective in a boot having a thin boot thickness, specifically, a bellows thickness of about 0.5 mm to 2.0 mm.

  The inclined surface 17a may be an inclined surface whose diameter decreases toward the final valley 16a as illustrated in FIG. 6, or may have a cylindrical shape as illustrated in FIG. Alternatively, as shown in FIG. 9, it may have a shape that once expands in the outer diameter direction and then decreases in diameter. Further, as illustrated in FIG. 6, the shoulder portion 17 may be designed to come into contact with the projecting portion 32 or the end surface 38 in the boot mounting portion of the outer joint member 2, or may be designed to provide a space.

  As shown in FIG. 7, the inner peripheral surface of the thick-walled portion 12b of the large-diameter mounting portion 12 of the boot 10 is continuously formed with a chamfered portion A and a linear portion F parallel to the axis from the end surface side. . The chamfered portion A is the same as that of the thin portion already described. As is clear from a comparison between FIG. 6 and FIG. 7, the thick portion 12 b is inevitably thick even in the shoulder portion 17.

  Protrusions E that are continuous over the entire circumference are formed on the inner circumferential surface of the large-diameter mounting portion 12 of the boot 10. This protrusion E is located in the said linear part B and F in a thin part and a thick part. The cross-sectional shape of the protrusion E may be a semicircle or a semi-ellipse, but a triangle is more preferable. In the illustrated embodiment, the protrusion E has a triangular cross section, and the apex is directed radially inward of the boot, that is, toward the axial center. The protrusion E contacts the boot groove 30 of the outer joint member 2 and exhibits a sealing function. Two or more protrusions E may be provided. Alternatively, a discontinuous protrusion different from the protrusion E may be provided. By tightening with the band 13, the protrusion E uniformly adheres to the boot groove 30 of the non-cylindrical boot mounting portion of the outer joint member 2 on the circumference and exhibits a sufficient sealing property. The bottom surface of the boot groove 30 of the outer joint member 2 with which the protrusion E is in close contact is smooth. The bottom surface of the boot groove 30 may have various shapes such as providing a protrusion, but is preferably smooth from the viewpoint of the processing man-hour of the outer joint member 2.

  The protrusion E in the large-diameter mounting portion 12 of the boot 10 is smoothly connected by rounding a concave arc at the boundary between the thin portion 12a and the thick portion 12b. As a result, as shown in FIG. 10, the boot is connected to the outer joint member more than other portions of the normal tightening margin at the joint portion of the two different curved surfaces at the circumferential end portion of the boot groove 30 of the outer joint member 2. It becomes possible to bite in and the sealing performance is improved. However, if the radius of curvature is too large, the central portion is “bearing” and a gap is generated, resulting in a decrease in sealing performance. Therefore, the radius of curvature of the roundness is preferably 0.5 mm or more and 5 mm or less.

  As for the margin of the recess C and the protrusion E and the boot attachment portion of the outer joint member 2, the protrusion E part overcomes the protrusion 32 of the outer joint member 2 due to elastic deformation, and the protrusion E and the outer joint member 2 The setting which can maintain sufficient sealing performance between the boot grooves 30 is required.

  When the material of the boot is high, such as when the material of the boot is a thermoplastic elastomer, especially a thermoplastic polyester elastomer with a type D durometer hardness of 35 or more and 50 or less according to JIS K 6253, this tightening setting is important. is there. The margin for the protrusion 32 of the recess C provided in the large-diameter mounting portion 12 of the boot 10 attached thereto is 0.1 to 1.0 mm in radius and the boot groove 30 at the tip of the protrusion E It is preferable that the interference with respect to the radius is 0.1 mm or more and 1.5 or less. Furthermore, the height of the protrusion E is preferably 0.3 mm or greater and 1.0 mm or less.

  With the tightening setting as described above, the large-diameter mounting portion 12 of the boot 10 can be attached to the protrusion E beyond the protruding portion 32 of the outer joint member 2, and then tightened with the band 13, The large-diameter attachment portion 12 of the boot 10 can be attached in close contact with the boot attachment portion of the outer joint member 2. If it is set to be smaller than the above-mentioned tightening margin, there is a possibility that a gap is locally generated by the deformation of the boot 10 when the band 13 is tightened. On the other hand, if the setting is larger than the above-described tightening margin, it is difficult to attach the boot. Moreover, when the height of the protrusion E is less than 0.3 mm, the adhesion of the outer joint member 2 to the groove 30 is lowered, and sufficient sealing performance cannot be obtained. When the height of the protrusion E exceeds 1.0 mm, the volume of the protrusion becomes too large, which is not efficient in terms of design and sealing properties.

  The recess C and the protrusion E of the boot 10 are preferably positioned within the range of the width of the band groove 18. With such a configuration, the band tightening force is transmitted to the protrusion E in the vertical direction, and the restraint in the axial direction of the recess C fitted to the protrusion 32 is strengthened. Sex is obtained.

  By the way, when the ambient temperature becomes high due to the effect of heat dissipation from the exhaust pipe, such as a sliding type constant velocity universal joint on the differential side of the drive shaft for automobiles, it is used in an environment that is easily affected by the heat Or, when the constant velocity universal joint is affected by heat, such as when used in an environment where the constant velocity universal joint itself generates heat, the air in the joint expands to increase the internal pressure. At the same time, since the boot material affected by heat is softened more than at normal temperature, the boot rigidity is lowered, and the deformation amount of the part having low design rigidity is further increased than the other parts. The sliding-type constant velocity universal joint is more sensitive to deformation because the internal volume changes due to sliding (plunging). Normally, the bellows portion 16 of the boot 10 is designed so that the stress is evenly distributed to all parts from the small-diameter mounting portion 14 to the large-diameter mounting portion 12 in consideration of dispersion of stress at the time of boot deformation at room temperature. The

However, especially when the sliding type constant velocity universal joint is frequently exposed to a high temperature, stress is concentrated near the small-diameter mounting portion 14. In the conventional design in which the stress is uniformly distributed throughout the bellows portion 16, the small-diameter rising portion, that is, the slope portion from the small-diameter mounting portion 14 to the first mountain m ₁ is bent near the first mountain m ₁ toward the small-diameter mounting portion 14 side. Deformation such as warping tends to occur. As a result, the durability near the small-diameter mounting portion 14 may be reduced. Therefore, at least the small-diameter rising portion of the bellows portion 16 or the slope portion from the first mountain m ₁ to the first valley n ₁ is made thicker than the other portions, so that Increases rigidity and suppresses deformation. The remaining portion of the bellows portion 16, that is, the portion from the first mountain m ₁ or the first valley n ₁ to the large-diameter mounting portion 12 is designed so that the stress is evenly distributed. By setting it as such a structure, the fall of durability of the small diameter attaching part 14 vicinity can be suppressed.

  This is particularly effective when the boot material is a thermoplastic polyester elastomer having a type D durometer hardness of 35 or more and 50 or less according to JIS K 6253. In the conventional boot made of thermoplastic elastomer, when the boot is compressed in the axial direction, it initially shrinks evenly like a spring, but at a certain point, the small diameter rising part reverses toward the small diameter mounting part 14 side. However, by improving the rigidity in the vicinity of the small-diameter rising portion as in this embodiment, the small-diameter rising portion can be uniformly deformed to the end without inversion, and particularly improves the durability of the boot 10 at high temperatures. Can be made. Here, “to the last” means a state in which the boot 10 is compressed in the axial direction and the slopes of all adjacent mountains are in contact with each other.

  Table 1 compares the test results of durability and sealing performance of large-diameter mounting parts, which were carried out on conventional thermoplastic elastomer boots (comparative example) and thermoplastic elastomer boots according to the embodiment (examples). Show. Test conditions were determined by inspecting the state of the boot after a continuous operation for a predetermined time at an operating angle θ = 10 deg and a rotation speed of 1200 rpm. Regarding durability, “good” means that continuous operation is possible, and “bad” means that it has been damaged. As for sealing performance (large-diameter mounting portion), “good” means no grease leakage, and “bad” means that grease leakage occurred.

  Although the tripod type constant velocity universal joint is taken as an example in the above description, the present invention can be applied to all constant velocity universal joints in which the boot mounting portion of the outer joint member has a non-cylindrical shape. For example, as shown in FIGS. 11 to 13, the invention can be applied to a tripod type in which the boot attachment portion of the outer joint member is not cylindrical. Further, the present invention can be applied to a constant velocity universal joint using a ball as a torque transmission member other than the tripod type, such as a double offset type (see FIGS. 14 to 16) or a Zepper type (see FIG. 17).

It is a longitudinal cross-sectional view of a tripod type constant velocity universal joint. It is a cross-sectional view of the tripod type constant velocity universal joint of FIG. It is a principal part enlarged view of the outer joint member in FIG. It is a longitudinal cross-sectional view of boots. It is a right view of the boot of FIG. It is an enlarged view of the thin part of the boot of FIG. It is an enlarged view of the thick part of the boot of FIG. It is principal part sectional drawing of the boot which shows a modification, Comprising: (A) respond | corresponds to FIG. 6, (B) respond | corresponds to FIG. It is principal part sectional drawing of the boot which shows another modification, Comprising: (A) respond | corresponds to FIG. 6, (B) respond | corresponds to FIG. It is detail drawing of the contact part of an outer joint member and a boot, Comprising: (A) shows both separately and (B) shows the state which fitted the boot to the outer joint member. It is a perspective view of the outer joint member which shows another embodiment. It is a cross-sectional view of the outer joint member of FIG. FIG. 13 is an X-O-Y cross-sectional view of the outer joint member of FIG. 12. It is a perspective view of the outer joint member which shows another embodiment. It is a cross-sectional view of the outer joint member of FIG. It is a longitudinal cross-sectional view of the outer joint member of FIG. It is a perspective view of the outer joint member which shows another embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Tripod type constant velocity universal joint 2 Outer joint member 22 Mouse | mouth part 22a Large diameter part 22b Small diameter part 24 Track groove 30 Boot groove 32 Projection part 38 End surface 26 Stem part 28 Spline shaft 4 Tripod member 42 Boss
44 Spline hole 46 Leg shaft 6 Roller 8 Needle roller 10 Boot 12 Large diameter mounting portion 12a Thin portion 12b Thick portion 14 Small diameter mounting portion 16 Bellows portion 17 Shoulder portion 18 Band groove 19 Projection portion

Claims (10)

A constant velocity universal joint that connects the first rotary shaft and the second rotary shaft, the outer joint member that is coupled to the first rotary shaft so as to be able to transmit torque, and the second rotary shaft that is coupled so as to be able to transmit torque The inner joint member, the torque transmission member that transmits the torque interposed between the outer joint member and the inner joint member, and the outer joint member and the second rotating shaft are mounted to fill the inside of the joint. A thermoplastic elastomer boot for preventing leakage of grease and entry of foreign matter from the outside,
A boot mounting portion of the outer joint member has a non-cylindrical outer peripheral surface;
The boot has a large-diameter attachment portion that is attached to the outer joint member, a small-diameter attachment portion that is attached to the second rotating shaft, and a bellows portion that connects the large-diameter attachment portion and the small-diameter attachment portion. The outer peripheral surface of the outer peripheral member has a cylindrical shape, the inner peripheral surface has a non-cylindrical shape along the contour of the boot mounting portion of the outer joint member, the entire volume of the large-diameter mounting portion is satisfied with the boot material, and at least the small-diameter mounting portion A constant velocity universal joint characterized in that a small-diameter rising portion from a first to an adjacent first mountain is thicker than other portions.   The thickness of the slope portion from the small diameter rising portion and the first mountain to the first valley is made thicker than the thickness from the first valley to the large diameter mounting portion. 1 constant velocity universal joint.   The constant velocity universal joint according to claim 1 or 2, wherein the large-diameter mounting portion has a shape in which a thick portion and a thin portion appear alternately in a circumferential direction.   The constant velocity universal joint according to any one of claims 1 to 3, wherein the boot is made of a thermoplastic polyester elastomer having a type D durometer hardness of 35 to 50 according to JIS K 6253.   The constant velocity universal joint according to any one of claims 1 to 4, wherein the outer joint member and the inner joint member can take an angular displacement and an axial displacement.   It has a large-diameter mounting portion that is attached to the outer joint member, a small-diameter mounting portion that is attached to the second rotating shaft, and a bellows portion that connects the large-diameter mounting portion and the small-diameter mounting portion. A cylindrical shape, the inner peripheral surface is a non-cylindrical shape along the contour of the boot attachment portion of the outer joint member, and the entire volume of the large diameter attachment portion is filled with the boot material, and at least the first mountain adjacent from the small diameter attachment portion. A boot made of a thermoplastic elastomer for a constant velocity universal joint, characterized in that a small-diameter rising portion is thicker than other portions.   The thickness of the small-diameter rising portion and the slope portion from the first mountain to the first valley is made thicker than the portion from the first valley to the large-diameter mounting portion. Thermoplastic elastomer boots for quick universal joints.   The thermoplastic elastomer boot for a constant velocity universal joint according to claim 6 or 7, wherein the large-diameter mounting portion has a shape in which a thick portion and a thin portion appear alternately in the circumferential direction.   The boot made of thermoplastic elastomer for a constant velocity universal joint according to any one of claims 6 to 8, characterized in that the material of the boot is a thermoplastic polyester elastomer having a type D durometer hardness of 35 to 50 according to JIS K 6253. .   The thermoplastic elastomer boot for a constant velocity universal joint according to any one of claims 6 to 9, wherein the outer joint member and the inner joint member can take an angular displacement and an axial displacement.

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