JP2007239878A - Drive shaft boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive shaft including sliding-type constant velocity universal joints at both ends of an intermediate shaft, in which the position of the intermediate shaft is restricted without any newly added retainer members such as a spring. <P>SOLUTION: The drive shaft of the invention comprises the intermediate shaft 10, the pair of the sliding-type constant velocity universal joints 20, 40 attached to both the ends of the intermediate shaft 10, and boots 16, 18 arranged to extend between the outer peripheries of outer rings of the constant velocity universal joints and the outer periphery of the intermediate shaft so as to retain lubricant therein. The boot 16 (and/or the boot 18) is integrated with a spring 8a for urging the intermediate shaft 10 in one axial direction to thereby restrict the axial movement of the intermediate shaft 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boot for a drive shaft having a sliding constant velocity universal joint attached to both ends of a solid or hollow shaft used for power transmission of automobiles and various industrial machines.

  A drive axle for transmitting power from a final reduction gear device (differential) of an automobile to drive wheels is also called a drive shaft. The drive shaft shown in FIG. 5 includes an intermediate shaft 1 and sliding constant velocity universal joints 2 and 2 attached to both ends thereof. The constant velocity universal joint 2 includes an outer ring (outer joint member) 3 and an inner ring (inner joint member) 4. The outer ring 3 includes a cup-shaped mouth portion and a stem portion, and is coupled to, for example, an axle of a drive wheel at the stem portion. The mouse portion has three track grooves 5 equally arranged in the circumferential direction on the inner periphery, and the opposite side walls of each track groove 5 serve as a roller guide surface. The inner ring 4 is connected to the intermediate shaft 1 by spline or serration. Three trunnions 6 projecting in the radial direction are equally arranged in the inner ring 4 in the circumferential direction, and each trunnion 6 supports a roller 7 so as to be rotatable, slidable and swingable. The trunnion 6 of the inner ring 4 enters the track groove 5 of the outer ring 3. Then, when the inner ring 4 rotates with respect to the outer ring 3 in a state of axial displacement and / or angular displacement, the roller 7 rolls along the roller guide surface.

  Since each constant velocity universal joint is a sliding type, the outer ring 3 and the inner ring 4 can be relatively displaced in the axial direction. Therefore, the intermediate shaft 1 can also be displaced in the axial direction together with the inner ring 4 fixed at both ends. As a result, the intermediate shaft 1 and the outer ring 3 come into contact with each other to generate abnormal noise. In order to prevent this, a compression coil spring 8 is interposed between the end of the intermediate shaft 1 and the outer ring 3 (coil spring 32 in FIG. 4 of Patent Document 1 and spring 9 in FIG. 2 of Patent Document 2). . In this case, since the other end of the intermediate shaft 1 is in contact with the outer ring 3 of the other constant velocity universal joint 2, a receiving member 9 having a good friction characteristic is attached to the outer ring 3 side.

On the other hand, since the inside of the boot is a large-capacity closed space, there is a problem that the grease does not sufficiently spread to the joint portion requiring lubrication. In order to solve this problem, Patent Document 3 proposes a spiral bellows boot. This helical bellows boot reduces the filling amount of grease by controlling the flow of grease in the boot to the joint side by a spiral groove.
US Pat. No. 3,613,396 (FIGS. 1 and 4) No. 6-12258 (column 3, line 39-column 4, line 18, FIG. 2) JP-A-8-177875

  In the case of a drive shaft using sliding type constant velocity universal joints on both sides, it is necessary to constrain the axial position of the intermediate shaft as described above. If there is no holding member such as a spring for restraining the axial position of the intermediate shaft, the intermediate shaft may collide with the outer ring or the like during the rotation and break them. However, when the intermediate shaft is constrained by a member such as a spring, the cost of the drive shaft is increased due to an increase in the number of parts, an increase in machining parts, and an increase in assembly man-hours.

  An object of the present invention is to provide a drive shaft capable of restraining the position of an intermediate shaft in an existing component configuration without separately providing an arrangement space such as a spring.

  In order to solve the above-mentioned problems, the invention of claim 1 is directed to an intermediate shaft, a pair of sliding constant velocity universal joints attached to both ends of the intermediate shaft, an outer ring outer diameter of each constant velocity universal joint, In a boot used in a drive shaft having a boot disposed between and having a lubricant therein, the intermediate shaft is urged toward the boot in one of the axial directions. It is characterized by integrating a spring for restricting the axial movement of the.

  According to a second aspect of the present invention, in the first aspect of the present invention, a spiral groove is formed on the inner peripheral surface of the boot, and the intermediate shaft is urged toward one of the axial directions along the spiral groove. A coil spring for restricting the axial movement of the shaft is provided.

  The invention of claim 3 is characterized in that the coil spring is integrally formed with the boot.

  The invention of claim 4 is characterized in that the coil spring is assembled along the spiral peak or valley of the boot.

  A fifth aspect of the present invention is a drive shaft having the boot according to any one of the first to fourth aspects.

  The main function of the boot used in the drive shaft is to retain the lubricant, but the boot shape of the constant velocity universal joint is often bellows to cope with bending and expansion / contraction. The bellows-shaped boot functions as a spring element to some extent. On the other hand, a spiral bellows boot has also been proposed in order to save the grease filling amount by controlling the flow of grease in the boot as described above. In the present invention, the spring for positioning the intermediate shaft is integrated with the boot so that the spring mounting portion is omitted from the joint so that the processing of the spring mounting portion becomes unnecessary.

  In the present invention, when the flow of grease is also controlled by adopting a spiral bellows boot, a coil spring can be conveniently arranged along the spiral groove of the boot. The spiral shape of the coil spring can be formed in accordance with the spiral groove, and the coil spring can be integrally attached to the inside and outside of the boot without protruding.

  By adopting a boot with an integrated spring, even if thrust acts on the intermediate shaft due to the bending and expansion of the constant velocity universal joint, the thrust of the intermediate shaft is canceled out by the biasing force of the spring, and the intermediate shaft is restrained in the axial direction. Thus, the intermediate shaft should not move beyond the allowable stroke. Boots are usually molded from a single member such as rubber or resin, but in the present invention, the boot thickness, the number of bellows peaks, the curvature of the peaks, etc. are optimally designed to ensure a certain degree of spring rigidity by the boots themselves. Furthermore, by combining and molding a plurality of different materials (rubber, resin, metal, etc.), a function equivalent to or higher than that of a spring provided in a conventional constant velocity universal joint is ensured.

  According to the present invention, since the axial position of the intermediate shaft can be constrained without significantly changing the configuration of the drive shaft, an increase in the number of parts, the number of processing steps, and the number of assembly steps can be avoided. Further, since the rigidity of the boot is increased by the spring integrated with the boot, it is possible to prevent the boot from being damaged when a jumping stone or the like collides with the boot.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention applied to a drive shaft of a front wheel drive type vehicle. In this embodiment, the spring 8 is eliminated from the conventional drive shaft of FIG. That is, in the drive shaft in which the triport type constant velocity universal joints 2 and 2 are disposed on both sides, the spring 8 that has been conventionally provided for restricting the axial movement of the intermediate shaft 1 is eliminated, and instead, the spring 8 is replaced. The other spring 8 a having the same spring stiffness as is integrated with the boot 16 of one constant velocity universal joint 20. Although it is possible to integrate a spring not on the boot 16 but on the opposite boot 18 or both boots 16, 18, the spring 8 a is integrated only on the boot 16 in this embodiment. Details of the spring stiffness of the boot 16 will be described later.

  The drive shaft includes an intermediate shaft 10 and sliding constant velocity universal joints 20 and 40 attached to both ends thereof. In the following, the right side of FIG. 1 is the inboard side and the left side is the outboard side. Spline or serration (hereinafter simply referred to as spline) shaft portions are formed at both ends of the intermediate shaft 10. In FIG. 1, reference numerals 16 and 18 denote boots. One boot 16 has a substantially uniform cylindrical shape as shown in FIGS. The boot 16 has a large diameter portion 16 a attached to the outer ring outer diameter of the constant velocity universal joint 20 and a small diameter portion 16 b attached to the intermediate shaft 10. The boot 18 on the opposite side has the same shape as the conventional one as shown in FIGS. 2B (a) and 2 (b). The boot 18 has a large diameter portion 18 a attached to the outer ring outer diameter of the constant velocity universal joint 40 and a small diameter portion 18 b attached to the intermediate shaft 10. Here, a so-called tripod type constant velocity universal joint is illustrated as a sliding type constant velocity universal joint.

  The constant velocity universal joint 20 on the outboard side includes an outer ring 22 and an inner ring 30. The outer ring 22 has a cup shape and is coupled to the axle of the driving wheel at the stem portion 24, for example. The outer ring 22 has three track grooves 26 equally distributed in the circumferential direction on the inner periphery, and the opposite side walls of each track groove 26 serve as a roller guide surface. The inner ring 30 has a spline hole 32 for coupling with the spline shaft portion 12 of the intermediate shaft 10. Three trunnions 34 projecting in the radial direction are equally arranged in the inner ring 30 in the circumferential direction. In this embodiment, the cross-sectional shape of each trunnion 34 is an ellipse whose minor axis extends in the axial direction of the joint, and the generatrix on the inner peripheral surface of the roller 36 is a convex arc. Therefore, the roller 36 can rotate, slide and swing with respect to the trunnion 34. The trunnion 34 and the roller 36 of the inner ring 30 are accommodated in the track groove 26 of the outer ring 22. When the inner ring 30 rotates with respect to the outer ring 22 in a state of axial displacement and / or angular displacement, the roller 36 rolls along the roller guide surface.

  In the present invention, as described above, the coil spring 8a incorporated in the boot 16 interposed between the outer ring 22 of the constant velocity universal joint 20 on the outboard side and the intermediate shaft 10 has a predetermined spring rigidity. In the case of this embodiment, the intermediate shaft 10 is biased toward the inboard side by the spring rigidity of the coil spring 8a.

  The constant velocity universal joint 40 on the inboard side is the same as the constant velocity universal joint 20 on the outboard side with respect to the basic configuration. Accordingly, substantially the same parts or portions are denoted by the same reference symbols throughout the drawings. In the constant velocity universal joint 40 on the inboard side, a receiving member 9 for receiving the end surface of the intermediate shaft 10 pushed by the boot 16 is attached to the bottom of the outer ring 22. The receiving member 9 has a concave spherical surface 9a, and the end of the intermediate shaft 10 has a convex spherical surface 10a. The convex spherical surface 10a slidably contacts the concave spherical surface 9a by the spring stiffness of the boot.

ここで、中間軸１０が軸方向に移動しないよう安定させるには、中間軸１０の速度及び加速度を「０」に近づければよい。したがって上式を整理して、

となる。［数３］は釣合いの式である。 Next, the spring rigidity of the coil spring 8a will be described. In the case of the conventional drive shaft of FIG. 5, forces generated by bending and expansion / contraction of the constant velocity universal joint: F1 (t), F2 (t), rigidity of the spring 8: K, rigidity of the boots 16, 18: k1 (x (t)), k2 (x (t)), damping of boots 16 and 18: c1 (x (t)), c2 (x (t)), allowable axial movement of intermediate shaft 10: x (t) Then, the mechanical concept of the drive shaft is illustrated as in FIG. In this case, the equation of motion of the intermediate shaft 10 can be expressed as the following [Equation 1].

Here, in order to stabilize the intermediate shaft 10 from moving in the axial direction, the speed and acceleration of the intermediate shaft 10 may be brought close to “0”. Therefore, the above formula is arranged,

It becomes. [Equation 3] is an equation of balance.

  Looking at [Equation 1] to [Equation 3], the sum of the rigidity of the spring 8 and the boots 16 and 18 (K + k1 + k2) controls the amount of movement due to the thrust acting on the intermediate shaft 10 by bending or expansion / contraction of the constant velocity universal joint. I understand that For example, when the spring 8 is incorporated in the boot 16, the spring stiffness K of the spring 8 is simply added to the stiffness k 1 of the boot 16, and the same balance equation as [Equation 3] is obtained. To establish.

  The boots 16 and 18 are originally used for retaining the lubricant, but often have a bellows structure because they must follow the bending and sliding of the constant velocity universal joints 20 and 40. Therefore, the boots 16 and 18 have a certain spring function. Since the boots 16 and 18 are generally molded of rubber or resin, the damping rate is larger than that of a metal spring, and an effect of alleviating the rapid stroke movement of the intermediate shaft 10 can be expected. Since the resin boot has higher rigidity than the rubber boot, it is suitable for restraining the axial movement of the intermediate shaft 10. However, when compared with metal springs, both rubber and resin boots cannot be denied the lack of spring rigidity. Therefore, the present invention integrates a metal spring into the boot.

  As an integrated structure of the coil spring with respect to the boot 16, a plurality of structures are possible as shown in FIGS. 4 (A) shows an example in which a coil spring 8a is integrated on the outside of the peak portion of the boot 16, FIG. 4 (B) shows an example in which the coil spring 8b is integrated in the inside of the peak portion, and FIG. The spring 8c is integrated, (D) is the coil spring 8d integrated on the outside of the valley, (E) is the coil spring 8e integrated in the valley, and (F) is the valley. A coil spring 8f is integrated on the inside of the part.

  The constant velocity universal joint used in the drive shaft of the present invention is preferably a tripod joint or a cross groove joint. The resultant force F1 (t) + F2 (t) of the axial force acting on the intermediate shaft by these joints can be reduced by appropriately managing the mounting phases of the two joints. Then, in the use application of the automobile, the resultant force F1 (t) + F2 (t) is estimated by calculation, and the stiffness of the boot including the spring is calculated from the value. In the case of a normal automobile drive shaft, generally, if (K + k1 + k2) is 1.0 N / mm or more and 20.0 N / mm or less of rigidity can be secured, the intermediate shaft 10 is a constant velocity universal joint outer ring 22. The intermediate shaft 10 can be held in a state in which the axial movement is restricted so as not to collide with.

The longitudinal cross-sectional view of the drive shaft which shows embodiment of this invention. It is an example of the boot used for the outboard side of the drive shaft of this invention, Comprising: (a) A boot side view, (b) A boot perspective view. It is an example of the boot used for the inboard side of the drive shaft of this invention, Comprising: (a) A boot side view, (b) A boot perspective view. The dynamic concept figure of the drive shaft of this invention. (A)-(f) is a fragmentary sectional view of the boot which shows the pan portion integrated with the boot. The longitudinal cross-sectional view of the conventional drive shaft.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Intermediate shaft 2 Tripport type sliding constant velocity universal joint 3 Outer ring 4 Inner ring 5 Track groove 6 Trunnion 7 Roller 9 Receiving member 9a Concave spherical surface 10 Intermediate shaft 10a Convex spherical surface 12 Spline shaft part 16 Boot 18 Boot 20 Sliding constant velocity Universal joint 22 Outer ring 24 Stem portion 26 Track groove 30 Inner ring 32 Spline hole 34 Trunnion 36 Roller 40 Sliding constant velocity universal joint

Claims (5)

  An intermediate shaft, a pair of sliding type constant velocity universal joints attached to both ends of the intermediate shaft, and an outer ring outer diameter and an intermediate shaft outer diameter of each constant velocity universal joint are provided with lubricant inside. In a boot used for a drive shaft having a holding boot, the boot is integrated with a spring that urges the intermediate shaft toward one of the axial directions and restricts the axial movement of the intermediate shaft. Features a drive shaft boot.   A spiral groove is formed on the inner peripheral surface of the boot, and a coil spring is disposed along the spiral groove to urge the intermediate shaft toward one of the axial directions and restrict axial movement of the intermediate shaft. The boot for drive shafts of Claim 1 characterized by the above-mentioned.   3. The drive shaft boot according to claim 2, wherein the coil spring is integrally formed with the boot.   3. The drive shaft boot according to claim 2, wherein the coil spring is assembled along a spiral peak or valley of the boot.   A drive shaft having the boot according to claim 1.

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