JP4794867B2 - Constant velocity universal joint with boots - Google Patents

Description

  The present invention relates to a constant velocity universal joint with a boot used in a power transmission system of an automobile or various industrial machines.

  The constant velocity universal joint is equipped with a boot for the purpose of preventing leakage of grease enclosed inside to the outside and preventing foreign matter from entering the constant velocity universal joint. This boot is generally mounted on the large-diameter mounting portion that is mounted on the boot mounting portion provided at the end of the outer joint member of the constant velocity universal joint, and on the boot mounting portion that is provided on the shaft connected to the constant velocity universal joint. A small-diameter mounting portion and a bent portion that integrally connects both mounting portions. As a boot for a constant velocity universal joint, a boot molded with rubber such as chloroprene, a boot molded with a thermoplastic elastomer, and the like are widely used.

  On the other hand, the constant velocity universal joint is a fixed type (Zepper type, Barfield type) that can take a large operating angle of θ = 45 to 50 deg. The operating angle cannot be so large, but the axis of the outer joint member There are sliding types (double offset type, tripod type, cross groove type) that have a mechanism that slides in the direction. As for the shape of the outer joint member, the contour shape of the opening part may be a cylindrical shape or the non-cylindrical shape may be used. There are many cases where it is more efficient to apply the non-cylindrical shape considering the internal structure from the viewpoint of weight reduction and workability of the constant velocity universal joint. Chloroprene rubber has been mainly used for boots applied to such non-cylindrical outer joint members.

In recent years, the application of thermoplastic elastomer boots has also been studied (Japanese Patent Laid-Open Nos. 10-110738, 10-196673, 2002-13546, 2003-194093, 2003). -329057).
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

  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). However, since it may not be sufficient depending on the use conditions, it tends to be replaced with a thermoplastic elastomer boot having better performance.

  However, a boot made of chloroprene rubber is mainly used for a constant velocity universal joint using an outer joint member whose contour shape forms a non-cylindrical shape. This is because it is difficult for a thermoplastic elastomer boot to form a large-diameter mounting portion into a non-cylindrical shape or a complicated shape. Alternatively, since the thermoplastic elastomer is somewhat poor in elastic properties and high in material hardness in terms of material characteristics, there are cases where the boot mounting property to the outer joint member is difficult, and the sealing performance may be insufficient.

  When the thermoplastic elastomer boot is applied to the non-cylindrical outer joint member, the non-cylindrical outer joint member is provided between the non-cylindrical outer joint member and the large-diameter mounting portion of the cylindrical boot, or the non-cylindrical outer joint member. In contrast, the large-diameter mounting portion of the boot is formed into a shape along the outer periphery of the outer joint member, and an elastic member (referred to as a bushing) is interposed between the outer surface of the large-diameter mounting portion of the non-cylindrical boot and the band. It is conceivable to use a type. However, this configuration increases the number of parts, which is not preferable for management and assembly processes. Moreover, the cost increases. Or since a certain amount of thickness is required for a bushing, an outer diameter dimension becomes large. Furthermore, the sealability at the contact portion between the outer ring / boot and between the boot / bushing is insufficient.

  On the other hand, it is also considered that the large-diameter mounting portion of the boot is formed with a substantially constant thickness along the non-cylindrical outer joint member, and the boot outer surface is tightened with a band shaped along the non-cylindrical shape. However, since the band has a complicated shape, the cost increases and the sealing performance is insufficient.

The constant velocity universal joint with a boot of the present invention is a constant velocity universal joint that connects the first rotating shaft and the second rotating shaft, and an outer joint member that is coupled to the first rotating shaft so as to be able to transmit torque, An inner joint member coupled to the second rotating shaft so as to be able to transmit torque; a torque transmitting member for transmitting torque interposed between the outer joint member and the inner joint member; an outer joint member and a second rotating shaft; In a constant velocity universal joint equipped with a boot made of a thermoplastic elastomer for preventing leakage of grease filled inside the joint and preventing entry of foreign matter from outside,
The outer peripheral surface of the boot mounting portion of the outer joint member is a non-cylindrical shape in which a large diameter portion and a small diameter portion appear alternately when viewed in a cross section, and when viewed in a vertical cross section, the large diameter portion is a boot groove, The outer joint member is located on the end face side and has a protruding portion having a diameter larger than that of the boot groove. The protruding portion has a first slope gradually expanding from the end face and a second slope gradually reducing in diameter as the distance from the end face increases. And the small diameter portion is linear,
The boot includes a large-diameter attachment portion that fits into the boot attachment portion of the outer joint member, a small-diameter attachment portion that fits into the second rotating shaft, and a bent portion between the large-diameter attachment portion and the small-diameter attachment portion. The large-diameter mounting portion is a shape in which the outer peripheral surface is circular and the inner peripheral surface conforms to the outer peripheral surface shape of the boot mounting portion of the outer joint member, and the thin-walled portion and the thick-walled portion appear alternately when viewed in cross section. Yes, all of the large-diameter mounting parts are filled with material, and when viewed in a longitudinal section, a band groove for receiving the boot band is formed on the outer periphery, and the inner periphery is from the end face to the chamfered part and the axis in the thin part Parallel straight portions, depressions, shoulder pads are formed continuously, and in the thick wall portion, chamfered portions and straight portions parallel to the axis are formed continuously,
The end surface side diameter of the chamfered portion of the thin portion is larger than the minimum diameter of the first slope,
The recess has a third slope and a fourth slope contacting the first slope and the second slope of the protrusion to receive the protrusion of the outer joint member;
A protrusion is formed on the inner peripheral surface of the large-diameter mounting portion of the boot over the entire circumference.
The protrusion and the recess are positioned within the range of the width of the band groove.

  According to the present invention, sufficient durability and sufficient sealing performance can be achieved at the same time, the number of components can be minimized, workability during assembly can be improved, and cost can be reduced. That is, since durability is improved and sufficient sealing performance can be ensured as compared with a boot made of chloroprene rubber, reliability of boot performance is improved. In addition, the number of parts can be kept to a minimum, and the cost can be reduced. Furthermore, according to the present invention, the boot mounting and positioning stability with respect to the outer joint member, and the mounting of the boot band to the band groove are facilitated, and the workability during assembly is improved.

  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 at the same time 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 material, 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 to 70 according to JIS K 6253, such as chloroprene, is effective, but a thermoplastic material having a type D durometer hardness of 35 to 50 according to JIS K 6253. In the case of a material having a high material hardness such as a polyester-based 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 bent portion 16 therebetween. In the illustrated embodiment, a bellows portion is shown as the bent portion 16, but the present invention can also be applied to boots other than the bellows type. 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 | channel 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 at the right end in FIG. 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 first slope of the protrusion 32. Corresponds to the second 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, and the shoulder pad D comes into contact with the end surface 38 of the outer joint member 2 in the axial direction. Positioning.

  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.

  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 in a concave arc shape 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.

  The area of the recess C and the protrusion E and the tightening margin of the outer joint member 2 with respect to the boot mounting portion is such that 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 tightening margin for the protrusion 32 of the recess C in the large-diameter mounting portion 12 of the boot 10 attached thereto is 0.1 mm or more and 1.0 mm or less in radius, and the tightening margin for the boot groove 30 at the tip of the protrusion E Is preferably from 0.1 mm to 1.5 mm in radius. 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.

  In the above description, the tripod type constant velocity universal joint is taken as an example, but 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 FIG. 11 thru | or FIG. 13, it can apply also to the thing where the boot attachment part of an outer joint member is not cylindrical shape among tripod type. Further, it can be applied to a constant velocity universal joint using a ball as a torque transmitting member other than the tripod type, for example, 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 13 Boot band 14 Small diameter mounting portion 15 Boot band 16 Bellow portion (bending portion)
18 Band groove 19 Projection

Claims (1)

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. In a constant velocity universal joint equipped with a thermoplastic elastomer boot for preventing leakage of grease and entry of foreign matter from the outside,
The outer peripheral surface of the boot mounting portion of the outer joint member is a non-cylindrical shape in which a large diameter portion and a small diameter portion appear alternately when viewed in a cross section, and when viewed in a vertical cross section, the large diameter portion is a boot groove, The outer joint member is located on the end face side and has a protruding portion having a diameter larger than that of the boot groove. The protruding portion has a first slope gradually expanding from the end face and a second slope gradually reducing in diameter as the distance from the end face increases. And the small diameter portion is linear,
The boot includes a large-diameter attachment portion that fits into the boot attachment portion of the outer joint member, a small-diameter attachment portion that fits into the second rotating shaft, and a bent portion between the large-diameter attachment portion and the small-diameter attachment portion. The large-diameter mounting portion is a shape in which the outer peripheral surface is circular and the inner peripheral surface conforms to the outer peripheral surface shape of the boot mounting portion of the outer joint member, and the thin-walled portion and the thick-walled portion appear alternately when viewed in cross section. Yes, all of the large-diameter mounting parts are filled with material, and when viewed in a longitudinal section, a band groove for receiving the boot band is formed on the outer periphery, and the inner periphery is from the end face to the chamfered part and the axis in the thin part Parallel straight portions, depressions, shoulder pads are formed continuously, and in the thick wall portion, chamfered portions and straight portions parallel to the axis are formed continuously,
The end surface side diameter of the chamfered portion of the thin portion is larger than the minimum diameter of the first slope,
The recess has a third slope and a fourth slope contacting the first slope and the second slope of the protrusion to receive the protrusion of the outer joint member;
A protrusion is formed on the inner peripheral surface of the large-diameter mounting portion of the boot over the entire circumference.
A constant velocity universal joint with a boot, wherein the protrusion and the depression are positioned within the width of the band groove.

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