JP6765231B2 - Boots for constant velocity universal joints and power transmission structure equipped with these boots - Google Patents

Description

The present invention relates to a boot for a constant velocity universal joint and a power transmission structure provided with the boot.

For example, a drive shaft that transmits power from an automobile transmission to wheels needs to allow angular displacement and axial displacement due to changes in the relative positional relationship between the transmission and the wheels. Therefore, the drive shaft is generally provided with a sliding constant velocity universal joint on the transmission side (inboard side) and a fixed constant velocity universal joint on the wheel side (outboard side). The structure is such that the joints are connected by an intermediate shaft.

Further, in the sliding type constant speed universal joint or the fixed type constant speed universal joint, the above-mentioned constant speed universal joint is used in order to prevent leakage of a lubricant such as grease sealed inside the joint and prevent foreign matter from entering from the outside of the joint. Boots are mounted between the outer joint member of the joint and the intermediate shaft. For this boot, for example, using a metal boot band, the large-diameter side end of the boot is tightened and fixed to the outer joint member, and the small-diameter side end is tightened and fixed to the intermediate shaft to form each constant velocity universal joint. It can be attached (see, for example, Patent Document 1).

By the way, the longitudinal dimension (width direction dimension of the drive shaft) of these constant velocity universal joints and the intermediate shaft is generally designed as appropriate according to the size of the transmission mounted on the vehicle. Therefore, for example, when the width direction dimension of the transmission to be mounted is large, it is necessary to shorten the width direction dimension of the drive shaft in order to maintain the width direction dimension (distance between wheels) of the vehicle at a predetermined size.

More specifically, as shown in FIG. 4, in the configuration in which the transmission 200 is located substantially in the center of the vehicle 100 in the width direction, the current size constant velocity universal joints 120, 130, 160 are provided on both the outboard side and the inboard side. , 170 and drive shafts 110, 150 with intermediate shafts 140, 180 are applied. In this case, separate boots 151 and 152 are attached between the outboard side constant velocity universal joints 120 and 130 and the intermediate shaft 140, and the inboard side constant velocity universal joints 160 and 170 and the intermediate shaft 180 are attached. Separate boots 190 and 210 are attached between the two. On the other hand, as shown in FIG. 5, for example, the transmission 200 is arranged at a position biased to one side in the width direction of the vehicle 100 in consideration of other components such as an engine (not shown). In this case, a drive shaft 110 (constant velocity universal joint 120, 130 or intermediate shaft 140) having a relatively small width direction is arranged on the offset side (left side in this figure) of the transmission 200, and the opposite side (FIG. 5). It becomes necessary to arrange a drive shaft 150 (constant velocity universal joint 160, 170 or intermediate shaft 180) having a relatively large width direction dimension (on the right side of the). Alternatively, as shown in FIG. 6, it is conceivable that the transmission 200 itself becomes larger in the width direction of the vehicle 100. In this case, drive shafts 110, 150 (constant velocity universal joints 120, 130, 160, 170 or intermediate shafts 140, 180), which are smaller in width direction than the configuration shown in FIG. Need to be placed.

However, as described in Patent Document 1, when both ends of the boot are fastened with a boot band, the outboard side boot is applied not only to the outer joint member of each constant velocity universal joint but also to the intermediate shaft. A part (boot fastening portion) for fastening the small diameter side end portion of the above and the small diameter side end portion of the inboard side boot to the intermediate shaft is required. Therefore, in a boot having a conventional configuration having a small width direction, it is necessary to secure an area for two boot fastening portions on the intermediate shaft, and as a result, there is a problem that the intermediate shaft cannot be shortened. ..

On the other hand, in Patent Document 2, a pair of flexible portions covering the joint portions of the constant velocity universal joints and a straight portion connecting the pair of flexible portions and covering the shaft connecting the constant velocity universal joints are integrated. Boots have been proposed.

Japanese Unexamined Patent Publication No. 2016-175777 Japanese Unexamined Patent Publication No. 2001-140849

With the boot described in Patent Document 2, since the intermediate shaft can be covered only by inserting the intermediate shaft into the straight portion, it is not necessary to provide the boot fastening portion on the intermediate shaft. Therefore, even if the total length (width direction dimension) of the drive shaft is limited by shortening the straight portion of the boot in accordance with the shortening of the intermediate shaft as shown in FIG. 5, each constant velocity The joint part of the universal joint can be covered with boots. However, the boots described in Patent Document 2 have a mounting structure in which both ends (large-diameter side ends of each flexible portion) are fastened to the outer joint member and the straight portion is not fixed to the intermediate shaft. The boot may be fastened to the outer joint member when the flexed portion is not properly expanded and contracted. That is, when attaching such an integrated boot, first insert the intermediate shaft into the straight part of the boot, and then fasten the outboard side end of the boot to the same velocity universal joint on the outboard side with a boot band. After that, the inboard side end of the intermediate shaft is connected to the inboard side constant velocity universal joint to fasten the inboard side end of the boot. As described above, if the large-diameter side end portion is fastened in a state where the straight portion of the boot is not positioned and fixed to the intermediate shaft, the expansion / contraction state of each of the bellows-shaped flexible portions is not stable. Therefore, the so-called outboard side boot set length and the inboard side boot sliding length may not be properly obtained.

In view of the above circumstances, in the present specification, the total length of the drive shaft is shortened to increase the degree of freedom in designing the drive shaft or its surroundings while allowing it to be appropriately deformed by following a predetermined angular displacement and axial displacement. Providing a new type of boots that can be used is a technical issue to be solved.

The solution to the above problems is achieved by the boot for a constant velocity universal joint according to the present invention. That is, this boot is a boot applied to a power transmission structure in which an outboard side constant velocity universal joint and an inboard side constant velocity universal joint are connected by a shaft, and is an outboard side constant velocity universal joint. A first flexible portion that covers the joint portion, a second flexible portion that covers the joint portion of the inboard side constant velocity universal joint, and a connecting portion that connects the first flexible portion to the second flexible portion. The connecting portion has a small diameter with respect to both the first flexible portion and the second flexible portion, and is provided with a boot band on the outboard side of the first flexible portion. A first tightening and fixing part is provided, a second tightening and fixing part by a boot band is provided on the inboard side of the second flexible part, and a third tightening and fixing part by a boot band is provided at the connecting part. It is characterized by the points provided.

As described above, in the present invention, two conventional boot band fastening type boots are integrated at the small diameter side end portion thereof, thereby reducing the number of boots to one. Further, not only the large-diameter side end portion of the boot but also the connecting portion as the small-diameter side end portion is provided with a tightening and fixing portion (third tightening and fixing portion) by the boot band. By providing the tightening fixing portion by the boot band in the connecting portion in this way, not only the distance between the outboard side constant velocity universal joint and the inboard side constant velocity universal joint can be shortened, but also the shaft connecting these joints can be connected to the boot. A part (connecting part) can be positioned and fixed. Therefore, it is possible to avoid the situation where the elastic state of the flexible portion is not stable as described above, and to attach the boot in the elastic state of the flexible portion. Of course, reducing the distance between the joints leads to space saving, so that it is possible to increase the degree of freedom in designing the power transmission device around these joints. In addition, the number of boots can be reduced from two to one, and the number of boot bands can be reduced from four (two on the small diameter side) to three (one on the small diameter side) compared to the conventional configuration. be able to. From the above, since a total of two parts can be reduced, it is possible to reduce not only the parts cost but also the manufacturing cost including the management cost. Further, since the connecting portion can be fastened to the shaft with the boot band, the inner space of the boot can be divided into two with the fastening portion as a boundary. This makes it possible to select and use the optimum grease (lubricant) for each of the outboard side constant velocity universal joint and the inboard side constant velocity universal joint. Therefore, it is possible to further improve the performance of the constant velocity universal joint, or to reduce the cost while maintaining the required performance.

Further, in the boot for a constant velocity universal joint according to the present invention, the first flexible portion, the second flexible portion, and the connecting portion may be integrally molded of the same material.

In this way, by integrally molding the first and second flexible portions and the connecting portions with the same material, it is possible to save the trouble of separately manufacturing the flexible portions and fixing them to each other. Therefore, this also makes it possible to reduce the manufacturing cost.

Further, in the boot for a constant velocity universal joint according to the present invention, even if the first flexible portion, the second flexible portion, and the connecting portion are all formed of a thermoplastic polyester-based elastomer. Good.

By forming both the flexible portion and the connecting portion having the above configuration with the thermoplastic polyester-based elastomer in this way, the boot having the above configuration can be formed by means such as blow molding, and the means for producing the boot is free. The degree increases.

Further, in the boot for a constant velocity universal joint according to the present invention, the axial dimension of the contact region between the connecting portion and the shaft is 1.0 times or more and 1.5 times the axial dimension of the third tightening and fixing portion. It may be set as follows.

By setting the axial dimension of the contact region between the connecting portion and the shaft as a relative value to the axial dimension of the third tightening and fixing portion in this way, the boot substantially functions as a flexible portion. The longitudinal dimension of the portion can be as large as possible. As a result, even when the shaft or the constant velocity universal joint takes a predetermined operating angle, the flexible portion can smoothly follow and deform without resistance. Therefore, it is possible to exhibit an excellent sealing function without impeding the power transmission behavior of the constant velocity universal joint. Of course, the smaller the contact area between the connecting portion and the shaft, the smaller the sliding resistance when the shaft is inserted, so that the boot assembly work can be performed smoothly.

The solution to the above problems is also achieved by the power transmission mechanism according to the present invention. That is, this power transmission mechanism includes an outboard side constant velocity universal joint, an inboard side constant velocity universal joint, a shaft connecting the outboard side constant velocity universal joint and the inboard side constant velocity universal joint, and a boot. In those equipped with an outboard side constant velocity universal joint, an inboard side constant velocity universal joint, and a plurality of boot bands for tightening and fixing the boot to the shaft, the boot is a joint of the outboard side constant velocity universal joint. A first flexible portion that covers the portion, a second flexible portion that covers the joint portion of the inboard side constant velocity universal joint, and a connecting portion that connects the first flexible portion to the second flexible portion. In this integrally formed boot, the outboard side of the first flexible portion is fastened and fixed by the first boot band to the outer periphery of the outer joint member of the outboard side constant velocity universal joint. , The inboard side of the second flexible part is tightened and fixed to the outer circumference of the outer joint member of the inboard side constant velocity universal joint by the second boot band, and the connecting part is tightened to the outer circumference of the shaft by the third boot band. It is characterized by a fixed point.

As described above, also in the power transmission structure according to the present invention, by providing the tightening fixing portion by the boot band in the connecting portion, the distance between the outboard side constant velocity universal joint and the inboard side constant velocity universal joint can be shortened. Instead, a part of the boot (connecting portion) can be positioned and fixed to the shaft connecting these joints. Therefore, it is possible to avoid the situation where the elastic state of the flexible portion is not stable as described above, and to attach the boot in the elastic state of the flexible portion. Of course, reducing the distance between the joints leads to space saving, so that it is possible to increase the degree of freedom in designing the power transmission device around these joints. Further, since the number of boots and the number of boot bands can be reduced as compared with the conventional configuration, it is possible to reduce not only the component cost but also the manufacturing cost including the management cost. Further, since the connecting portion can be fastened to the shaft with the boot band, the inner space of the boot can be divided into two with the fastening portion as a boundary. This makes it possible to select and use the optimum grease (lubricant) for each of the outboard side constant velocity universal joint and the inboard side constant velocity universal joint. Therefore, it is possible to further improve the performance of the constant velocity universal joint, or to reduce the cost while maintaining the required performance.

Of course, in this case, for the reason described above, in the power transmission structure according to the present invention, the first flexible portion, the second flexible portion, and the connecting portion are all formed of a thermoplastic polyester-based elastomer. Is preferable.

Further, for the reasons described above, in the power transmission structure according to the present invention, the axial dimension of the contact region between the connecting portion and the shaft is 1.0 times or more the axial dimension of the third tightening and fixing portion, and 1. It is preferably set to 5 times or less.

As described above, according to the present invention, the total length of the drive shaft is shortened while the drive shaft can be appropriately deformed according to a predetermined angular displacement and axial displacement, and the degree of freedom in designing the drive shaft or its surroundings is increased. It is possible to provide a new type of boot that can be used, or a power transmission structure equipped with this boot.

It is a figure which shows typically the structure of the main part of the front wheel drive system provided with the drive shaft which concerns on one Embodiment of this invention. It is sectional drawing of the drive shaft shown in FIG. It is sectional drawing of the boot for a constant velocity universal joint shown in FIG. It is a figure which shows typically the structure of the main part of the front wheel drive system which concerns on one conventional form. It is a figure which shows typically the structure of the main part of the front wheel drive system which concerns on other form. It is a figure which shows typically the structure of the main part of the front wheel drive system which concerns on other form.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The constant velocity universal joint in the following embodiment is incorporated in the drive shaft of an automobile, connects two shafts on the drive side and the driven side, and transmits rotational torque at a constant speed regardless of the operating angle of the two shafts. Examples thereof include a fixed constant velocity universal joint and a sliding constant velocity universal joint having such a structure.

FIG. 1 is a diagram schematically showing a configuration of a main part of a front wheel drive system according to an embodiment of the present invention. As shown in FIG. 1, the front-wheel drive system includes a transmission 200 arranged adjacent to an engine (not shown) of the vehicle 100 and both sides of the transmission 200 in the width direction (the width direction here is the vehicle 100). The drive shafts 10 and 150 are provided so as to correspond to the width direction of the above and correspond to the left-right direction in FIG. Since the transmission 200 is unevenly arranged in one of the width directions of the vehicle 100, the total lengths (width direction dimensions) of the drive shafts 10 and 150 connected to the transmission 200 are different. Hereinafter, the details of the drive shaft 10 on the left side in the width direction (the side having a relatively short total length) according to the present invention will be described.

FIG. 2 is a partial cross-sectional view of the drive shaft 10 according to the embodiment of the present invention. As shown in FIG. 2, the drive shaft 10 corresponds to the power transmission structure referred to in the present invention, and has a constant velocity universal joint 20 on the outboard side (wheel side), an inboard side (transmission 200 side), and the like. It has a structure in which a speed universal joint 30, an intermediate shaft 40 connecting the outboard side constant velocity universal joint 20 and the inboard side constant velocity universal joint 30, and a boot 50 are arranged. In the present embodiment, the outboard side constant velocity universal joint 20 is a fixed constant velocity universal joint, and the inboard side constant velocity universal joint 30 is a sliding constant velocity universal joint. Further, the intermediate shaft 40 referred to here corresponds to the shaft referred to in the present invention. The outboard side end 40a of the intermediate shaft 40 is connected to the inner joint member 26 that constitutes the outboard side constant velocity universal joint 20, and the inner joint member that constitutes the inboard side constant velocity universal joint 30 (here). Then, the inboard side end portion 40b of the intermediate shaft 40 is connected to the boss 36) of the tripod member 32. First, the configuration of the outboard side constant velocity universal joint 20 will be described.

As shown in FIG. 2, the outboard side constant velocity universal joint 20 includes an outer joint member 23 in which arcuate track grooves 21 extending in the axial direction are formed at a plurality of locations in the circumferential direction of the spherical inner peripheral surface 22. An inner joint member 26 in which arcuate track grooves 24 extending in the axial direction in pairs with the track groove 21 of the outer joint member 23 are formed at a plurality of locations in the circumferential direction of the spherical outer peripheral surface 25, and the outer joint member 23. A ball 27 that transmits torque between the track groove 21 and the track groove 24 of the inner joint member 26, a spherical inner peripheral surface 22 of the outer joint member 23, and a spherical outer peripheral surface 25 of the inner joint member 26. It is provided with a cage 28 arranged between the two to hold the ball 27.

As shown in FIG. 3, the inboard side constant velocity universal joint 30 is a so-called double roller type tripod type constant velocity universal joint, and mainly includes an outer joint member 31, a tripod member 32, and a roller unit 33. ..

On the inner peripheral surface of the outer joint member 31, three linear track grooves 34 extending in the axial direction (only one track groove 34 is displayed in FIG. 2) are formed at equal intervals in the circumferential direction. To. Each track groove 34 has a pair of roller guide surfaces 35 (only one roller guide surface 35 is displayed in FIG. 3) facing each other on both inner walls thereof. The roller guide surface 35 has an arcuate cross section and extends linearly in the axial direction of the outer joint member 31.

Although not shown, the tripod member 32 has three leg shafts 37 extending in the radial direction of the boss 36 integrally on the outer peripheral surface of the cylindrical boss 36 at equal intervals (120 ° intervals) in the circumferential direction. It is formed. The tip of the leg shaft 37 extends radially to the vicinity of the bottom of the track groove 34. The inboard side end 40b of the intermediate shaft 40 is connected to the shaft hole of the boss 36 by spline fitting or the like.

In the inboard side constant velocity universal joint 30 having the above configuration, the leg shaft 37 of the tripod member 32 and the roller guide surface 35 of the outer joint member 31 engage with each other in the rotational direction of the two shafts via the roller unit 33. , The rotational torque is transmitted from the drive side to the driven side at a constant speed. Further, since the roller unit 33 rolls on the roller guide surface 35 while rotating with respect to the leg shaft 37, relative axial displacement and angular displacement between the outer joint member 31 and the tripod member 32 are allowed. Will be done.

As shown in FIG. 3, the boot 50 integrally has a pair of flexible portions 51 and 52 and a connecting portion 53 connecting the pair of flexible portions 51 and 52. Here, as shown in FIG. 2, the first flexible portion 51 includes the joint portion (mainly the opening side of the outer joint member 23) of the outboard side constant velocity universal joint 20 and the outboard side of the intermediate shaft 40. In addition to covering, the second flexible portion 52 covers the joint portion (mainly the opening side of the outer joint member 31) of the inboard side constant velocity universal joint 30 and the inboard side of the intermediate shaft 40. Further, the connecting portion 53 arranged between the pair of flexible portions 51 and 52 covers the portion (center in the width direction) of the intermediate shaft 40 that is not covered by the pair of flexible portions 51 and 52. ..

As shown in FIG. 3, each of the flexible portions 51 and 52 has a so-called bellows shape, and has a form in which a plurality of peak portions 51a and 52a and valley portions 51b and 52b are alternately connected. As shown in FIGS. 2 and 3, the outer diameter of the mountain portion 51a of the first flexible portion 51 covering the outboard side constant velocity universal joint 20 is one end side in the longitudinal direction of the boot 50 (here, out). It shrinks from the board side) toward the center side (inboard side) in the longitudinal direction. As shown in FIGS. 2 and 3, the outer diameter dimension of the mountain portion 52a of the second flexible portion 52 that covers the inboard side constant velocity universal joint 30 is the other end side in the longitudinal direction of the boot 50 (here, here). It shrinks from the inboard side to the center side in the longitudinal direction (outboard side). Further, as shown in FIGS. 2 and 3, the inner diameter dimension of the valley portion 51b of the first flexible portion 51 is from one end side in the longitudinal direction (here, the outboard side) to the center side in the longitudinal direction (inboard) of the boot 50. It is shrinking toward the side). As shown in FIGS. 2 and 3, the inner diameter of the valley portion 52b of the second flexible portion 52 is from the other end side in the longitudinal direction (here, the inboard side) to the center side in the longitudinal direction (outboard side) of the boot 50. ), It is shrinking.

Further, in relation to the connecting portion 53, the outer diameter dimension of the connecting portion 53 is set so as to be smaller than the outer diameter dimension of the mountain portions 51a and 52a of the flexible portions 51 and 52 described above.

As shown in FIG. 2, a first tightening and fixing portion by a corresponding boot band (referred to as the first boot band 57) is attached to the outboard side end portion of the first flexible portion 51 located on the outboard side. 54 is provided. A second tightening and fixing portion 55 by a corresponding boot band (referred to as the second boot band 58) is provided at the inboard side end portion of the second flexible portion 52 located on the inboard side. Further, the connecting portion 53 arranged between the pair of flexible portions 51 and 52 is provided with a third tightening fixing portion 56 by a corresponding boot band (referred to as a third boot band 59). .. In the present embodiment, as shown in FIG. 2, the first tightening and fixing portion 54 is the inner surface 29 of the outer peripheral surface 29 of the outer joint member 23 of the outboard side constant velocity universal joint 20 by tightening the first boot band 57. It is fixed to the board side. Further, the second tightening and fixing portion 55 is fixed to the outboard side of the outer peripheral surface 38 of the outer joint member 31 of the inboard side constant velocity universal joint 30 by tightening the second boot band 58. Further, the third tightening and fixing portion 56 is fixed to the outer peripheral surface 41 of the large diameter portion 42 located at the center in the longitudinal direction of the intermediate shaft 40 by tightening the third boot band 59.

At this time, as shown in FIG. 3, a state in which the third tightening and fixing portion 56 is tightened and fixed to the large diameter portion 42 of the intermediate shaft 40 by the third boot band 59 (see FIG. 2) (FIG. 3). In the state indicated by the alternate long and short dash line), the axial dimension L1 of the contact region between the connecting portion 53 and the intermediate shaft 40 is, for example, 1.0 times or more the axial dimension L2 of the third tightening and fixing portion 56. It is set to 1.5 times or less.

As the boot bands 57 to 59 used here, those having any known configuration can be used. However, the boot band (third boot band 59) used for tightening the connecting portion 53 (third tightening fixing portion 56) having a relatively small outer diameter dimension has one end from the viewpoint of mounting workability. It is preferable that the structure is formed in an open band shape (or a ring shape that is not closed) and can approach the large diameter portion 42 of the intermediate shaft 40 from a direction (radial direction) orthogonal to the longitudinal direction thereof.

The boot 50 ensures flexibility enough to follow the behavior (angle displacement, axial displacement) of the constant velocity universal joints 20 and 30 when the constant velocity universal joints 20 and 30 rotate while taking a predetermined operating angle. It is made of, for example, rubber or resin because it needs to be. As the rubber material, those having a surface hardness of Hs50 or more and Hs70 or less are preferable. Specific examples include chloroprene rubber and silicone rubber. Further, as the resin material, a resin material having a surface hardness of HD38 or more and HD50 or less is preferable. Specific examples include a thermoplastic polyester-based elastomer or a composition containing a thermoplastic polyester-based elastomer. In particular, in the case of a thermoplastic elastomer as described above, by utilizing its property (thermoplasticity), the degree of freedom of the molding means is relatively high as compared with rubber, so that the center in the longitudinal direction (connecting portion 53) is at both ends thereof. Even boots 50 having a diameter smaller than that of the side (flexible portions 51 and 52) can be integrally molded relatively easily by, for example, blow molding.

As described above, in the present invention, the first flexible portion 51 that covers the joint portion of the outboard side constant velocity universal joint 20 and the second flexible portion 52 that covers the joint portion of the inboard side constant velocity universal joint 30. And were integrated by the connecting portion 53, thereby reducing the number of boots 50 to one. Further, the first and second tightening fixing portions 54 and 55 by the first and second boot bands 57 and 58 are provided at the large diameter side end portion of the boot 50, and the connecting portion as the small diameter side end portion of the boot 50. The 53 is provided with a third tightening fixing portion 56 by a third boot band 59. By providing the third tightening fixing portion 56 by the third boot band 59 in the connecting portion 53 in this way, not only can the distance between the outboard side constant velocity universal joint 20 and the inboard side constant velocity universal joint 30 be shortened. A part of the boot 50 (connecting portion 53) can be positioned and fixed to the intermediate shaft 40 connecting these constant velocity universal joints 20 and 30. Therefore, as described above, it is possible to avoid the situation where the elastic states of the flexible portions 51 and 52 are not stable, and to attach the boots 50 in an appropriate elastic state of the flexible portions 51 and 52. Of course, reducing the distance between the constant velocity universal joints 20 and 30 leads to space saving, so the degree of freedom in designing the power transmission device (transmission 200, engine, etc.) around these constant velocity universal joints 20 and 30. Can be increased. Further, since the number of boots and the number of boot bands can be reduced by one as compared with the conventional configuration, it is possible to reduce not only the parts cost but also the manufacturing cost including the management cost. Further, since the connecting portion 53 can be fastened to the intermediate shaft 40 by the third boot band 59, the inner space of the boot 50 can be divided into two with the fastening portion as a boundary (see FIG. 2). This makes it possible to select and use the optimum grease (lubricant) for each of the outboard side constant velocity universal joint 20 and the inboard side constant velocity universal joint 30. Therefore, it is possible to further improve the performance of each of the constant velocity universal joints 20 and 30, or to reduce the cost while maintaining the required performance.

Although one embodiment of the present invention has been described above, of course, the boot 50 can take other forms within the scope of the present invention.

That is, in the above embodiment, the boot 50 in which the pair of flexible portions 51 and 52 and the connecting portion 53 are integrally molded with the same material is illustrated, but of course, other configurations can be adopted. For example, a part or all of the first to third tightening fixing portions 57 to 59 may be made of metal, and the rest may be integrally molded (insert molded) with the above-mentioned resin or elastomer.

Further, in the above description, the zipper type constant velocity universal joint is exemplified as the outboard side constant velocity universal joint 20 according to the present invention, but of course, other types of fixed constant velocity universal joints such as the undercut free type can be used. It is also possible to apply. Similarly, in the above description, the double roller type tripod type constant velocity universal joint is exemplified as the inboard side constant velocity universal joint 30 according to the present invention, but of course, the single roller type tripod type constant velocity universal joint is also used. It can also be applied to sliding type constant velocity universal joints other than tripod type, such as double offset type constant velocity universal joints and cross group type constant velocity universal joints.

Further, in the above description, the case where the boots according to the present invention are applied to the constant velocity universal joints 20 and 30 forming a part of the drive shaft 10 has been illustrated, but the boots according to the present invention have other rotations such as a propeller shaft. It can be applied to various power transmission structures as well as shafts.

10, 110, 150 Drive shaft 20, 120, 160 Outboard side constant velocity universal joint 23 Outer joint member 30, 130, 170 Inboard side constant velocity universal joint 30 Sliding constant velocity universal joint 31 Outer joint member 40, 140 , 180 Intermediate shaft 50 boots (invention)
51, 52 Flexible part 53 Connecting part 54, 55, 56 Tightening fixing part 57, 58, 59 Boot band 100 Vehicle 151,152,190,210 Boots (conventional)
200 transmission

Claims (4)

An outboard side constant velocity universal joint, an inboard side constant velocity universal joint, a shaft connecting the outboard side constant velocity universal joint and the inboard side constant velocity universal joint, boots, the outboard side, etc. In a power transmission structure including a speed universal joint, the inboard side constant speed universal joint, and a plurality of boot bands for tightening and fixing the boot to the shaft.
The shaft has a large diameter portion at an intermediate position in the longitudinal direction thereof.
The boot includes a first flexible portion that covers the joint portion of the outboard side constant velocity universal joint, a second flexible portion that covers the joint portion of the inboard side constant velocity universal joint, and the first. It integrally has a connecting portion that connects the flexible portion to the second flexible portion.
The connecting part has a small diameter with respect to both the first flexible part and the second flexible part.
In the integrally formed boot, the outboard side of the first flexible portion is fastened and fixed to the outer periphery of the outer joint member of the outboard side constant velocity universal joint by the first boot band.
The inboard side of the second flexible portion is tightened and fixed to the outer periphery of the outer joint member of the inboard side constant velocity universal joint by a second boot band, and the connecting portion is attached to the large diameter portion of the shaft. A power transmission structure characterized by being tightened and fixed by three boot bands. The power transmission structure according to claim 1, wherein the first flexible portion, the second flexible portion, and the connecting portion are integrally molded of the same material . The power transmission structure according to claim 1 or 2 , wherein the first flexible portion, the second flexible portion, and the connecting portion are all formed of a thermoplastic polyester-based elastomer. Claims 1 to 3 in which the axial dimension of the contact region between the connecting portion and the shaft is set to 1.0 times or more and 1.5 times or less the axial dimension of the third tightening and fixing portion. The power transmission structure according to any one of the above.

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