JP2021008929A - Constant velocity universal joint boot fitting structure - Google Patents

Abstract

To prevent deterioration in fixing force of a boot with respect to an outside joint member as much as possible.SOLUTION: A boot fitting structure fits and fixes a large diameter cylinder part 21 of a boot 21 to an outside joint member 2 of a boot fitting part 16 by tightening the large diameter cylinder part 21 with a boot band 15 to deform and contract the diameter thereof. The outside joint member 2 is integrated with an annular swollen part 17 that is disposed adjacent to one side in an axial direction of the boot fitting part 16 and hangs over on a radial outside relative to the boot fitting part 16, and satisfies a relational expression of D1>D2, where D1 represents an outer diameter dimension of the swollen part 17 and D2 represents an inner diameter dimension of the boot band 15 when tightening the large diameter cylinder part 21.SELECTED DRAWING: Figure 2

Description

The present invention relates to a mounting structure for boots for constant velocity universal joints.

An automobile equipped with an engine or an electric motor as a drive source on the chassis is equipped with a power transmission device such as a drive shaft or a propeller shaft in order to transmit the output of the drive source to the drive wheels. Of these, the drive shaft is arranged on the drive wheel side (outboard side) and has a fixed constant velocity universal joint that allows only angular displacement, and is arranged on the drive source side (inboard side), and has angular displacement and axial direction. A sliding type constant velocity universal joint that allows displacement and a shaft member (intermediate shaft) that connects the inner joint members of the above two constant velocity universal joints so as to be able to transmit torque are provided.

In the drive shaft, tubular boots are provided between the intermediate shaft and the outer joint member of the fixed constant velocity universal joint, and between the intermediate shaft and the outer joint member of the sliding constant velocity universal joint. As the boots, boots made of rubber or resin (thermoplastic elastomer) that can be elastically deformed according to the relative displacement of the outer joint member and the inner joint member (intermediate shaft) are adopted. The boot integrally has a tubular portion (large diameter tubular portion and a small diameter tubular portion) provided at one end and the other end in the axial direction, and a bellows portion connecting both tubular portions. The large-diameter tubular portion and the small-diameter tubular portion are mounted and fixed in close contact with the cup portion and the intermediate shaft of the outer joint member, respectively. This prevents the lubricant such as grease filled in the joint from leaking to the outside and foreign matter from entering the joint.

The boot is often attached and fixed to a mating member (outer joint member or intermediate shaft) by using a strip-shaped fastening member (boot band) as described in Patent Document 1 below.

Japanese Unexamined Patent Publication No. 2011-252594

By the way, when the outer joint member and the inner joint member are relatively displaced, the bellows portion of the boot is deformed in a manner that follows this, but as shown in FIG. 5, the constant velocity universal joint 100 with the boot operates greatly. When the outer joint member 101 and the inner joint member (intermediate shaft 102 connected to) rotate relative to each other in a state where the bellows portion 103b of the boot 103 is significantly compressed and deformed at a corner, the boot band 104 is formed as shown in FIG. The position of the boot band 104 is displaced in the axial direction with respect to the predetermined mounting position (the position of the boot band 104 shown by the broken line in the figure) (the boot band 104 is displaced from the predetermined mounting position), and the boot 103 has a sealing function to be guaranteed. It turns out that it can be compromised. The main reason for such a problem is that when the bellows portion 103b of the boot 103 is greatly compressed and deformed, the boot band 104 is axially unidirectional with respect to the boot band 104 from the bellows portion 103b (left side of paper in FIGS. 5 and 6). It is considered that this is because the boot band 104 slides to one side in the axial direction due to the axial load P that presses against the large diameter cylinder portion 103a, and the tightening force to be applied to the large diameter tubular portion 103a is reduced.

When the axial load P is applied to the boot band 104, the reaction force of the axial load P acts on the bellows portion 103b of the boot 103, so that the bellows portion 103b can be elastically deformed by receiving the reaction force. If so, it is considered that the axial load P applied to the boot band 104 is reduced. However, the rigidity of the boot 103 made of an elastic material such as rubber or resin tends to increase as the ambient temperature decreases. Therefore, when the constant velocity universal joint 100 with boots is placed in a low temperature environment, the load is sufficiently reduced. No effect can be expected and the above problems are more likely to occur.

In view of the above circumstances, a main object of the present invention is in a mounting structure for a boot for a constant velocity universal joint, in which a large diameter tubular portion of the boot is mounted and fixed to an outer joint member of the constant velocity universal joint using a boot band. It is an object of the present invention to prevent the boot band from being displaced in the axial direction with respect to a predetermined mounting position as much as possible, so that a desired sealing function can be stably maintained.

The present invention, which was conceived to achieve the above object, integrally forms a large-diameter tubular portion formed of an elastic material in a tubular shape and provided at one end in the axial direction, and a bellows portion connected to the large-diameter tubular portion. Among the boots for constant velocity universal joints, the large diameter tubular portion is tightened with a boot band to reduce the diameter, so that the large diameter tubular portion is attached to the annular boot mounting portion provided on the outer joint member of the constant velocity universal joint. In the mounting structure of a boot for a constant velocity universal joint that is mounted and fixed in a close contact state, the outer joint member is arranged adjacent to one side in the axial direction of the boot mounting portion, and is an annular shape that projects radially outward from the boot mounting portion. It has an integral bulge, and when the outer diameter of the bulge is D1 and the inner diameter of the boot band tightening the large diameter cylinder is D2, the relational expression D1> D2 is satisfied. And.

According to the above configuration, even if the boot band tightening the large-diameter tubular portion of the boot receives an axial load applied from the bellows portion of the boot and slides to one side in the axial direction, the boot band is a member of the outer joint member. Since it engages with the bulge in the axial direction, further sliding movement of the boot band can be restricted. Therefore, if the bulging portion is provided at an appropriate axial position, the boot band (large diameter tubular portion of the boot) can be placed in the predetermined mounting position regardless of the operating temperature conditions of the constant velocity universal joint and the rigidity of the boot. On the other hand, it is possible to prevent the position from being displaced in the axial direction (being out of the predetermined mounting position). As a result, it is possible to prevent the boot band from reducing the tightening force in the diameter-reducing direction that should be applied to the large-diameter tubular portion of the boot, so that the boot can stably exhibit the desired sealing function. A fast universal joint can be realized.

In the above configuration, among the outer joint members, the outer diameter surface of the bulging portion is a molded surface formed by forging, and the surface defining the boot mounting portion is a surface finished by machining after forging. be able to. According to such a configuration, the outer joint member having both the bulging portion and the boot mounting portion can be obtained by machining a part of the base material of the outer joint member obtained by the forging process. It is possible to obtain a constant velocity universal joint capable of exhibiting the effects of the above at low cost.

In order to increase the fixing force of the boot to the outer joint member, it is preferable to provide a plurality of annular protrusions on the boot mounting portion so as to be axially separated from each other. In such a configuration, the band width of the boot band is W, and the annular protrusion located on the other side in the axial direction of the plurality of annular protrusions and the end portion on the other side in the axial direction of the bulge (one side in the axial direction of the boot mounting portion). When the axial separation distance from the end of the outer joint member is X, if the relational expression W> X is satisfied, the boot band under the axial load will be in the bulging part of the outer joint member and in the axial direction. All of the plurality of annular protrusions can be covered with the boot band even when sliding to one side in the axial direction until they are engaged. As a result, it is possible to suppress or prevent a decrease in the fixing force of the boot to the outer joint member.

As the elastic material constituting the boot, a rubber material or a resin material (a material containing a thermoplastic elastomer as a main component) can be adopted. That is, the present invention can be applied without any problem when either so-called rubber boots or resin boots are used as the boots. However, since resin boots are lighter and more excellent in bending durability than rubber boots, it is preferable to use resin boots in order to realize a lightweight and durable constant velocity universal joint with boots.

The present invention determines whether the constant velocity universal joint is a fixed constant velocity universal joint that allows only angular displacement, or a sliding constant velocity universal joint that allows both angular displacement and axial displacement. Can be applied without.

As described above, according to the present invention, in the mounting structure of a boot for a constant velocity universal joint, the large diameter tubular portion of the boot is attached and fixed to the outer joint member of the constant velocity universal joint using a boot band. Since it is possible to prevent the band from being displaced in the axial direction with respect to a predetermined mounting position, it is possible to stably maintain the desired sealing function that the boot should ensure. As a result, it is possible to realize a power transmission device such as a constant velocity universal joint with boots and a drive shaft, which are highly durable and reliable.

It is a vertical cross-sectional view of the constant velocity universal joint with a boot which adopted the boot mounting structure which concerns on embodiment of this invention. It is an enlarged view of the part A of FIG. It is an enlarged view of the part A of FIG. 1 when an axial load is applied to a boot band. It is a partial vertical sectional view for demonstrating the manufacturing procedure of the outer joint member shown in FIG. It is a figure which shows the state which took the working angle of the constant velocity universal joint with boots. It is a partial vertical sectional view of FIG. 5, and is a figure for demonstrating the problem of the conventional structure.

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

FIG. 1 is a vertical cross-sectional view of a constant velocity universal joint (constant velocity universal joint with boots) adopting the boot mounting structure according to the embodiment of the present invention. More specifically, the operating angle of the equivalent velocity universal joint is 0 °. It is a vertical sectional view in the state of. The constant velocity universal joint 1 shown in the figure is, for example, a fixed constant velocity universal joint that constitutes a drive shaft of an automobile together with a sliding constant velocity universal joint (not shown), and the drive shaft is incorporated in the automobile. Is arranged on the drive wheel side (outboard side) and allows only angular displacement. The fixed constant velocity universal joint 1 is a barfield type (BJ) including an outer joint member 2, an inner joint member 3, a plurality of balls 4, and a cage 5, and its maximum operating angle (outside). The maximum value of the relative angular displacement of the joint member 2 and the inner joint member 3) is set to more than 40 ° (for example, 44 °). In FIG. 1, the left side of the paper surface (the bottom side of the cup portion 6 of the outer joint member 2) is the outboard side, and the right side of the paper surface (the opening side of the cup portion 6) is the inboard side. In the following description, the outboard side is referred to as "one side in the axial direction", and the inboard side is referred to as "the other side in the axial direction".

The outer joint member 2 is made of a metal material (steel material) such as carbon steel for machine structure (carbon steel that has been heat-treated such as quenching and tempering) such as S40C, SBM40C, and S53C. It integrally has a bottomed tubular cup portion 6 having an open end on the other side in the direction and a shaft portion 7 extending from the bottom of the cup portion 6 to one side in the axial direction. A plurality of (for example, six) arcuate track grooves 8 extending in the axial direction are formed on the spherical inner peripheral surface of the cup portion 6. Although not shown, the internal space of the cup portion 6 is filled with grease as a lubricant.

The inner joint member 3 is made of the same metal material as the outer joint member 2 and is formed in an annular shape (short cylindrical shape), and a plurality of circles paired with the track groove 8 of the outer joint member 2 are formed on the spherical outer peripheral surface thereof. An arcuate track groove 9 is formed. The inner joint member 3 has a central hole 3a opened on both end surfaces thereof, and an end portion of a metal shaft member 10 on one side in the axial direction is spline-fitted into the central hole 3a. An annular grooves 11 and 12 are formed on the outer peripheral surface of the shaft member 10, and the retaining rings 13 and 14 fitted to the annular grooves 11 and 12 prevent the shaft member 10 from coming off from the inner joint member 3. ing. The shaft member 10 is also referred to as an intermediate shaft, and its end on the other side in the axial direction is connected to an inner joint member of a sliding constant velocity universal joint (not shown) so as to be able to transmit torque by spline fitting or the like. To.

The balls 4 are interposed between the track grooves 8 of the outer joint member 2 and the track grooves 9 of the inner joint member 3 to transmit torque between the two joint members 2 and 3. The cage 5 is arranged between the spherical inner peripheral surface of the outer joint member 2 and the spherical outer peripheral surface of the inner joint member 3, and has a pocket portion 5a for holding the ball 4.

Between the cup portion 6 of the outer joint member 2 and the shaft member 10, a tubular shape is provided to prevent the grease filled in the internal space of the cup portion 6 (inside the joint) from leaking to the outside and foreign matter from entering the joint. Boots 20 are provided. The boot 20 of the present embodiment is a so-called resin boot made of a resin material containing a thermoplastic elastomer such as polyester, polyurethane, polyolefin, polyamide, polystyrene, and fluorine as a main component, and is axially one side. A large-diameter tubular portion 21 provided at the side end and attached and fixed to the cup portion 6 of the outer joint member 2 using a metal boot band 15, and a boot band provided at the other end in the axial direction. A small-diameter tubular portion (not shown) attached and fixed to the shaft member 10 using the above, and a bellows portion 22 that is interposed between the large-diameter tubular portion 21 and the small-diameter tubular portion and connects both tubular portions are integrally provided. .. The bellows portion 22 has peaks and valleys alternately arranged in the axial direction, and the constant velocity universal joint 1 takes an operating angle (the outer joint member 2 and the inner joint member 3 are relatively angularly displaced). ), It elastically expands and contracts and bends and deforms.

Hereinafter, the mounting mode of the large-diameter tubular portion 21 of the boot 20 to the outer joint member 2 will be described in detail with reference to FIG. 2, which is an enlarged view of the A portion of FIG.

As shown in FIG. 2, an annular band mounting groove 21a is formed on the outer diameter surface of the large diameter tubular portion 21 of the boot 20. The boot band 15 tightens the band mounting groove 21a (the bottom surface of the groove) to reduce the diameter of the large-diameter tubular portion 21 so that the large-diameter tubular portion 21 is formed on the outer diameter surface 6a of the cup portion 6 of the outer joint member 2. It is mounted and fixed in close contact with the boot mounting portion 16 provided. A rib 21b projecting outward in the radial direction is provided on one side of the band mounting groove 21a in the axial direction. The ribs 21b may be provided over the entire circumference of the large-diameter tubular portion 21 to form an annular shape, or may be provided intermittently in the circumferential direction to form an arc shape.

The boot mounting portion 16 is provided with a plurality of (two in this case) annular protrusions 16a and 16b, and the tops of the respective annular protrusions 16a and 16b bite into the inner diameter surface of the large diameter tubular portion 21. As a result, the outer joint member 2 and the large-diameter tubular portion 21 of the boot 20 are engaged in the axial direction, so that the fixing force of the boot 20 to the outer joint member 2 is increased.

On one side of the boot mounting portion 16 in the axial direction, an annular (short cylindrical) bulging portion 17 is provided adjacent to the boot mounting portion 16 so as to project radially outward from the boot mounting portion 16. The outer diameter surface 17a of the bulging portion 17 is formed on a cylindrical surface having a constant diameter without unevenness, and the outer diameter dimension (diameter dimension) D1 is a boot band 15 in which the large diameter tubular portion 21 of the boot 20 is tightened. It is set to be larger than the inner diameter dimension D2 of (D1> D2).

In the constant velocity universal joint 1 with boots having the above configuration, when this takes an operating angle (when the outer joint member 2 and the inner joint member 3 are relatively angularly displaced), the bellows portion of the boot 20 follows this. 22 elastically expands and contracts and bends and deforms. Then, when torque is transmitted between the outer joint member 2 and the inner joint member 3 in a state where the vicinity of the end portion on one side in the axial direction of the bellows portion 22 is significantly compressed and deformed, as shown in FIG. An axial load P that presses the boot band 15 that tightens the large-diameter tubular portion 21 of the boot 20 from the bellows portion 22 of the boot 20 to one side in the axial direction is applied, and the boot band 15 that receives this is predetermined. There is a possibility of sliding over the rib 21b by sliding from the mounting position (the position shown by the broken line in the figure) to one side in the axial direction.

However, when the axial load P is applied to the boot band 15, the reaction force of the axial load P acts on the bellows portion 22 of the boots 20, so that the bellows portion 22 receives the reaction force and elastically deforms. For example, it is considered that the axial load P applied to the boot band 15 is reduced. However, the boot 20 of the present embodiment is a so-called resin boot, and its rigidity increases as the ambient temperature of the boot 20 decreases. Further, the rigidity of the grease interposed in the internal space of the boot 20 tends to increase as the ambient temperature decreases. Therefore, particularly when the axial load P is applied to the boot band 15 while the constant velocity universal joint 1 is placed in a low temperature environment, the above load reducing effect cannot be sufficiently obtained, and the boot band 15 cannot be sufficiently obtained. Axial misalignment is likely to occur.

On the other hand, as in the present embodiment, between the outer diameter dimension D1 of the bulging portion 17 provided on the outer joint member 2 and the inner diameter dimension D2 of the boot band 15 tightening the large diameter tubular portion 21 of the boot 20. If the relational expression of D1> D2 is established, the boot band 15 and the outer joint member 2 bulge even if the boot band 15 that receives the axial load P slides to one side in the axial direction. The portion 17 engages in the axial direction, and further sliding movement of the boot band 15 is restricted. Therefore, if the bulging portion 17 is provided at an appropriate axial position, the boot band 15 is predetermined regardless of the usage environment of the constant velocity universal joint 1 and the rigidity of the boot 20 and the grease filled in the internal space thereof. It is possible to prevent the position from being displaced in the axial direction with respect to the mounting position of the. As a result, the large-diameter tubular portion 21 of the boot 20 can be tightened with a predetermined tightening force, so that a constant-velocity universal joint 1 with boots capable of stably exhibiting a desired sealing function can be realized.

In this embodiment, in order to increase the fixing force of the boot 20 to the outer joint member 2, a plurality of (two) annular protrusions 16a and 16b are provided on the boot mounting portion 16 of the outer joint member 2 so as to be axially separated from each other. , The axial distance X (see FIG. 2) between the top of the annular protrusion 16b located on the other side of the two annular protrusions 16a and 16b and the end of the bulge 17 on the other side in the axial direction, and the boot. A bulging portion 17 is provided between the band 15 and the band width W (see FIG. 2) so that the relational expression of W> X is established.

In this case, as shown in FIG. 3, even when the boot band 15 that has received the axial load P slides to one side in the axial direction until it engages with the bulging portion 17 in the axial direction, the annular protrusion 16a Since both 16b and 16b can be covered with the boot band 15, it is possible to prevent a decrease in the fixing force of the boot 20 to the outer joint member 2.

Further, in the outer joint member 2 of the present embodiment, the outer diameter surface 17a of the bulging portion 17 is forged (the outer diameter surface 17a is a molded surface formed by forging), and the bulging portion 17 and the outer diameter surface 17a are axially formed. The defined surface of the adjacent boot mounting portion 16 is a surface finished by machining (cutting or turning) after forging. That is, in the present embodiment, the boot mounting portion 16 and the bulging portion 17 to be provided on the outer diameter surface 6a of the cup portion 6 are forged by being mounted on a steel bar or extruded backward, as schematically shown in FIG. After obtaining a base material 2'in a substantially finished product shape, a part of the base material 2'(a cup-shaped part 6'finally finished in the cup part 6 has a constant diameter by forging. A part of the outer diameter surface 6a'formed on the cylindrical surface is obtained by machining (the portion to be forged by machining is shown by the broken line in the lower figure of FIG. 4). The part indicated by cross-hatching).

On the other hand, although detailed illustration is omitted, the conventional outer joint member 101 (see FIG. 6) which does not have the bulging portion 17 and has only the boot mounting portion is usually the base material 2 shown on the upper side of the paper surface of FIG. Since it is obtained by thinning the portion corresponding to the bulging portion 17 by machining after obtaining ‘’, it is necessary to increase the machining amount as compared with the case of obtaining the outer joint member 2 of the present embodiment. And the cost is high. Conversely, the outer joint member 2 of the present embodiment having the annular bulging portion 17 having the outer diameter surface 17a finished with a forged skin requires a smaller amount of machining than the conventional outer joint member 101. , Can be obtained at low cost.

Further, if the outer diameter surface 17a of the bulging portion 17 is forged skin finish, the surface layer portion of the bulging portion 17 becomes a layer having a high hardness due to work hardening accompanying the forging process. Therefore, when the metal boot band 15 engages with the bulging portion 17 in the axial direction, the possibility that the bulging portion 17 is deformed or the like is reduced. Therefore, the movement restricting portion of the boot band 15 included in the bulging portion 17 The function as is improved.

Although the mounting structure of the boots for the constant velocity universal joint (the constant velocity universal joint 1 with boots 1) according to the embodiment of the present invention has been described above, the embodiment of the present invention is not limited to this.

For example, the present invention can be preferably applied when a so-called rubber boot made of a rubber material is used instead of the so-called resin boot as the boot 20. However, since the resin boot is lighter than the rubber boot and has excellent bending durability and the like, it is advantageous in realizing the constant velocity universal joint 1 with boots which is lightweight and has excellent durability and reliability.

Further, the boot mounting portion 16 provided on the outer diameter surface 6a of the cup portion 6 of the outer joint member 2 may be provided with three or more annular protrusions separated from each other in the axial direction.

Further, in the above, the boot mounting structure according to the present invention is applied to the barfield type fixed constant velocity universal joint (BJ), but the boot mounting structure according to the present invention is the undercut free type (UJ). It is also possible to apply to other known fixed constant velocity universal joints. Further, the boot mounting structure according to the present invention can be applied not only to a fixed constant velocity universal joint that allows only angular displacement, but also to a sliding constant velocity universal joint that allows angular displacement and axial displacement. .. Examples of the sliding type constant velocity universal joint include a double offset type (DOJ), a tripod type (TJ), and a cross groove type (LJ).

The present invention is not limited to the embodiments described above, and it goes without saying that the present invention can be further implemented in various embodiments without departing from the gist of the present invention. The scope of the present invention is indicated by the scope of claims, and further includes the equal meaning described in the scope of claims, and all modifications within the scope.

1 Constant velocity universal joint (constant velocity universal joint with boots)
2 Outer joint member 3 Inner joint member 4 Ball 5 Cage 10 Shaft member (intermediate shaft)
15 Boot band 16 Boot mounting part 16a, 16b Ring protrusion 17 Protruding part 17a Outer diameter surface 20 Boot 21 Large diameter tubular part 21a Band mounting groove 22 Bellows part D1 (of bulging part) Outer diameter dimension D2 (of boot band) Inner diameter dimension W Band width X Axial separation distance

Claims (4)

Of the boots for constant velocity universal joints, which are formed of an elastic material and have a large-diameter tubular portion provided at one end in the axial direction and a bellows portion connected to the large-diameter tubular portion, the large-diameter tubular portion Is attached and fixed to the annular boot mounting portion provided on the outer joint member of the constant velocity universal joint by tightening with a boot band to reduce the diameter of the large diameter tubular portion. In the mounting structure of
The outer joint member is arranged adjacent to one side in the axial direction of the boot mounting portion, and integrally has an annular bulging portion that projects radially outward from the boot mounting portion.
When the outer diameter of the bulging portion is D1 and the inner diameter of the boot band to which the large diameter cylinder is tightened is D2, the boot for a constant velocity universal joint is characterized by satisfying the relational expression of D1> D2. Mounting structure. The first aspect of claim 1, wherein the outer diameter surface of the bulging portion is a molded surface formed by forging, and the surface defining the boot mounting portion is a surface finished by machining after the forging. Mounting structure for boots for constant velocity universal joints. The boot mounting portion has a plurality of annular protrusions provided apart from each other in the axial direction.
The band width of the boot band is W, and the axial separation distance between the annular protrusion located on the other side in the axial direction of the plurality of annular protrusions and the end on the other side in the axial direction of the bulge is X. When, the mounting structure of the boot for a constant velocity universal joint according to claim 1 or 2, which satisfies the relational expression of W> X. The mounting structure for boots for a constant velocity universal joint according to any one of claims 1 to 3, wherein the elastic material is a resin material.

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