JP2018123898A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent floating of an end part of a boot to improve sealability.SOLUTION: A constant velocity universal joint includes an outside joint member, and an inside joint member configured to transmit rotational torque with angular displacement allowed via a ball between itself and the outside joint member, wherein on an outer peripheral surface of a shaft 17 extending from the inside joint member, a small-diameter end part 25 extending from a bellows part 26 of a boot 23 is fastened and fixed by a boot band 28. On an inner peripheral surface of a boundary portion between the bellows part 26 of the boot 23 and the small-diameter end part 25, an annular projection 32 is provided, and an annular concave groove 33 engaged with the projection 32 is formed on the outer peripheral surface of the shaft 17.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a constant velocity universal joint provided with a boot that is used in a power transmission system of an automobile or various industrial machines, for example, a drive shaft or a propeller shaft of an automobile and prevents lubricant leakage from the inside of the joint.

  For example, there are two types of constant velocity universal joints that are used as means for transmitting a rotational force from an automobile engine to wheels at a constant velocity: a fixed constant velocity universal joint and a sliding constant velocity universal joint. Both of these constant velocity universal joints have a structure in which two shafts on the driving side and the driven side are connected so that rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle.

  A drive shaft that transmits power from the engine to the wheels needs to cope with angular displacement and axial displacement caused by a change in the relative positional relationship between the engine and the wheels. Therefore, the drive shaft is generally equipped with a sliding type constant velocity universal joint on the engine side (inboard side) and a fixed type constant velocity universal joint on the wheel side (outboard side). It has a structure in which universal joints are connected by a shaft.

  This type of constant velocity universal joint includes a cup-shaped outer joint member, an inner joint member, and a torque transmission member, and has a structure in which a lubricant is sealed in the inner space of the outer joint member. By enclosing the lubricant, the lubricity at the sliding portion inside the joint is ensured when the joint is operated.

  In this way, the constant velocity universal joint in which the lubricant is enclosed has a shaft extending from the outer joint member and the inner joint member in order to prevent the leakage of the lubricant from the inside of the joint and to prevent foreign matter from entering from the outside of the joint. A structure in which a rubber or resin bellows-like boot is mounted is provided (for example, see Patent Document 1).

  One end portion extending from the bellows portion of the boot is fastened and fixed to the outer peripheral surface of the opening portion of the outer joint member by a boot band. The other end portion extending from the bellows portion of the boot is fastened and fixed to the outer peripheral surface of the shaft extending from the inner joint member by a boot band.

JP 2008-95815 A

  By the way, the constant velocity universal joint disclosed in Patent Document 1 has a structure in which a bulging portion is formed on the inner peripheral surface of the end portion of the boot and a concave portion is formed on the outer peripheral surface of the shaft. Thus, the end portion of the boot is fastened and fixed to the outer peripheral surface of the shaft by the boot band by fitting the bulging portion of the boot into the concave portion of the shaft.

  By adopting such a structure, the end of the boot can be stably attached to the shaft, the position of the end of the boot with respect to the shaft is prevented from being displaced, and the sealability of the boot is ensured. ing.

  However, during operation of the constant velocity universal joint, the shaft may swing significantly (angular displacement) or slide (axial displacement) with respect to the outer joint member. In that case, the bellows portion of the boot is also greatly oscillated or slid with the movement of the shaft.

  Therefore, a force that lifts the end of the boot fastened and fixed by the boot band acts. In this way, if the boot bellows part swings or slides repeatedly, the lubricant enclosed in the joint may enter between the end part of the boot and the shaft and the lubricant may leak to the outside. There is.

  Therefore, the present invention has been proposed in view of the above-mentioned problems, and the object of the present invention is to provide a constant velocity universal joint that can prevent the end of the boot from being lifted and improve the sealing performance. is there.

  A constant velocity universal joint according to the present invention includes an outer joint member and an inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member via the torque transmission member. The end part extended from the bellows part of a boot is fastened and fixed to the outer peripheral surface of the shaft member extended from a boot band.

  As a technical means for achieving the above-described object, the present invention provides an annular protrusion on the inner peripheral surface of the boundary portion between the bellows portion and the end portion of the boot, and an annular concave groove with which the protrusion engages. It was formed on the outer peripheral surface of the shaft member.

  In the present invention, during operation of the constant velocity universal joint, even if the shaft member greatly oscillates or slides with respect to the outer joint member, the accordion portion of the boot greatly oscillates or slides. By engaging the protrusion of the boot with the concave groove of the shaft member, it is possible to prevent the end of the boot from being lifted.

  Thereby, it can suppress that the lubricant enclosed inside the joint penetrates between the end portion of the boot and the shaft member, and the lubricant leaks to the outside, and the sealing performance of the boot can be secured.

  The protrusion and the groove in the present invention desirably have a structure that is arranged so as to overlap the boot band in the axial direction.

  If such a structure is adopted, it becomes easy to maintain the engagement state between the protrusion of the boot and the concave groove of the shaft member by tightening with the boot band. Therefore, it is possible to reliably prevent the boot end from being lifted, and it is easy to prevent the leakage of the lubricant and ensure the boot sealing performance.

  The protrusion and the groove in the present invention preferably have a structure in which the cross section along the axial direction is rectangular.

  If such a structure is adopted, the engagement state between the protrusion of the boot and the groove of the shaft member becomes strong with the cross-sectional shape of the protrusion and the groove. Therefore, it is possible to reliably prevent the boot end from being lifted, and it is easy to prevent the leakage of the lubricant and ensure the boot sealing performance.

  According to the present invention, during the operation of the constant velocity universal joint, the movement in which the bellows portion of the boot greatly swings or slides as the shaft member swings or slides greatly with respect to the outer joint member is repeated. However, it is possible to prevent the end of the boot from being lifted by engaging the protrusion of the boot with the concave groove of the shaft member.

  Thereby, it can suppress that the lubricant enclosed inside the joint penetrates between the end portion of the boot and the shaft member, and the lubricant leaks to the outside, and the sealing performance of the boot can be secured. As a result, a constant velocity universal joint with a long life and high reliability can be provided.

In embodiment of this invention, it is a principal part expanded sectional view which shows the state before attaching the edge part of a boot to a shaft. In embodiment of this invention, it is a principal part expanded sectional view which shows the state after attaching the edge part of a boot to a shaft. It is sectional drawing which shows the whole structure of a constant velocity universal joint in embodiment of this invention. It is sectional drawing which shows the state which took the operating angle of the constant velocity universal joint of FIG.

  An embodiment of a constant velocity universal joint according to the present invention will be described in detail below based on the drawings.

  In the following embodiments, a fixed type constant velocity universal joint that is incorporated in a drive shaft for an automobile, connects two shafts on the driving side and the driven side, and transmits rotational torque at a constant speed even when the two shafts have an operating angle. An example is a Rzeppa type constant velocity universal joint.

  The present invention can be applied to other fixed type constant velocity universal joints such as an undercut free type constant velocity universal joint in addition to the Rzeppa type constant velocity universal joint. Further, the present invention can also be applied to a sliding type constant velocity universal joint such as a tripod type or a double offset type constant velocity universal joint. Furthermore, the present invention can also be applied to a fixed type constant velocity universal joint and a sliding type constant velocity universal joint incorporated in an automobile propeller shaft.

  As shown in FIG. 3, a fixed type constant velocity universal joint (hereinafter, simply referred to as a constant velocity universal joint) of this embodiment includes a cup-shaped outer joint member 12 having an opening 11, an inner joint member 13, and torque transmission. The main part is composed of a plurality of balls 14 and a cage 15 which are members.

  This constant velocity universal joint has a structure in which an internal part composed of an inner joint member 13, a ball 14 and a cage 15 can be angularly displaced with respect to the outer joint member 12.

  One end of a shaft 17 that is a shaft member is connected to the shaft hole 16 of the inner joint member 13 so that torque can be transmitted by spline fitting. The shaft 17 extending from the inner joint member 13 is prevented from coming off from the inner joint member 13 by a retaining ring 18.

  In the outer joint member 12, arc-shaped track grooves 19 extending in the axial direction are formed at equal intervals in a plurality of locations in the circumferential direction of the spherical inner peripheral surface 20. In the inner joint member 13, arc-shaped track grooves 21 that extend in the axial direction in pairs with the track grooves 19 of the outer joint member 12 are formed at a plurality of positions in the circumferential direction of the spherical outer peripheral surface 22 at equal intervals.

  The ball 14 is interposed between the track groove 19 of the outer joint member 12 and the track groove 21 of the inner joint member 13 to transmit rotational torque. The cage 15 is disposed between the inner peripheral surface 20 of the outer joint member 12 and the outer peripheral surface 22 of the inner joint member 13 to hold the ball 14. The number of balls 14 may be 6, 8, or any number, and the number is arbitrary.

  In the constant velocity universal joint having the above-described configuration, a lubricant such as grease (not shown) is sealed in the inner space of the outer joint member 12, so that the sliding portion inside the joint, that is, the outer With respect to the joint member 12, the lubricity at the sliding portion of the internal part composed of the inner joint member 13, the ball 14 and the cage 15 is ensured.

  This constant velocity universal joint is made of resin between the opening 11 of the outer joint member 12 and the shaft 17 in order to prevent leakage of the lubricant enclosed in the joint and prevent foreign matter from entering from the outside of the joint. Alternatively, a seal structure equipped with a rubber bellows-like boot 23 is provided.

  The boot 23 includes a large-diameter end 24 fastened and fixed to the outer peripheral surface of the opening 11 of the outer joint member 12 by a boot band 27, and a small-diameter end 25 fixed to the outer peripheral surface of the shaft 17 by a boot band 28. The large-diameter end portion 24 and the small-diameter end portion 25 are connected to each other, and the telescopic bellows portion 26 is reduced in diameter from the large-diameter end portion 24 toward the small-diameter end portion 25.

  When the boot 23 is made of resin, the surface hardness is preferably HDD38-50. Examples of the material of the boot 23 include thermoplastic elastomers such as ester, olefin, urethane, amide, and styrene.

  If the surface hardness is smaller than that of the HDD 38, the heat resistance is reduced, the cost of the boot 23 is increased, and the strength is reduced. On the contrary, if the surface hardness is larger than that of the HDD 50, the fatigue property, flexibility, and assembling property are lowered.

  When the boot 23 is made of rubber, the surface hardness is preferably Hs 50 to 70. Examples of the material of the boot 23 include chloroprene rubber and silicon rubber.

  If the surface hardness is smaller than Hs50, the strength of the boot 23 is reduced. On the other hand, if the surface hardness is higher than Hs70, the fatigue property is reduced.

  In this embodiment, a boot mounting structure in which the small-diameter end portion 25 of the boot 23 is mounted on the shaft 17 will be exemplified and described in detail below.

  As shown in FIGS. 1 and 2, the bulging portion 29 is formed on the inner peripheral surface of the small diameter end portion 25 of the boot 23, and the concave portion 30 is formed on the outer peripheral surface of the shaft 17. On the other hand, a groove 31 for positioning the boot band 28 with respect to the small diameter end portion 25 of the boot 23 is formed on the outer peripheral surface of the small diameter end portion 25 of the boot 23.

  When the small-diameter end portion 25 of the boot 23 is attached to the shaft 17, the bulging portion 29 of the small-diameter end portion 25 of the boot 23 is fitted into the concave portion 30 of the shaft 17, so The end 25 is positioned in the axial direction.

  In this state, the boot band 28 is fitted into the concave groove 31 of the small diameter end portion 25 of the boot 23, and the small diameter end portion 25 of the boot 23 is tightened by the boot band 28. 17 is fixed.

  As shown in FIGS. 1 and 2, the characteristic configuration of the constant velocity universal joint in this embodiment is provided with an annular protrusion 32 on the inner peripheral surface of the boundary portion between the bellows portion 26 and the small diameter end portion 25 of the boot 23. At the same time, an annular concave groove 33 with which the protrusion 32 engages is formed on the outer peripheral surface of the shaft 17.

  The protrusion 32 of the boot 23 and the concave groove 33 of the shaft 17 have a rectangular cross section along the axial direction. For example, it is effective to set the axial dimension t of the protrusion 32 to 3 mm and the radial dimension d to 2 mm (see FIG. 1).

  Further, the protrusion 32 of the boot 23 and the concave groove 33 of the shaft 17 are arranged so as to overlap the boot band 28 in the axial direction (see L portion in FIG. 2). For example, the overlapping portion L is effective when less than 10% of the axial dimension of the bootband 28 is effective.

  During operation of the constant velocity universal joint, as shown in FIG. 4, the shaft 17 may swing significantly (angular displacement) with respect to the outer joint member 12. In that case, the bellows portion 26 of the boot 23 also swings greatly with the movement of the shaft 17.

  At this time, a force is applied so that the boundary portion between the bellows portion 26 and the small diameter end portion 25 of the boot 23 is lifted (see the portion X in FIG. 4).

  However, in this embodiment, even when the bellows portion 26 of the boot 23 is repeatedly swung, the protrusion 32 of the boot 23 and the groove 33 of the shaft 17 exhibit the following stopper function.

  That is, as shown in FIG. 2, the axial end surface 34 of the protrusion 32 of the boot 23 is formed in the concave groove of the shaft 17 even if a force that lifts the boundary portion between the bellows portion 26 and the small diameter end portion 25 of the boot 23 acts. It is caught on the 33 axial wall surface 35.

  As described above, the protrusion 32 of the small diameter end portion 25 of the boot 23 is engaged with the concave groove 33 of the shaft 17, thereby preventing the boundary portion between the bellows portion 26 and the small diameter end portion 25 of the boot 23 from being lifted. be able to.

  Accordingly, even if the bellows portion 26 of the boot 23 is repeatedly swung, the lubricant enclosed in the joint enters between the small diameter end portion 25 of the boot 23 and the shaft 17 and the lubricant is externally applied. It is possible to suppress leakage of the boot 23 and to secure the sealing performance of the boot 23.

  In the above structure, since the protrusion 32 of the boot 23 and the concave groove 33 of the shaft 17 are arranged so as to overlap the boot band 28 in the axial direction, the protrusion 32 of the boot 23 and the shaft 17 of the shaft 17 are tightened by the boot band 28. It becomes easy to maintain the engaged state with the concave groove 33.

  Therefore, it is possible to reliably prevent the boundary portion between the bellows portion 26 and the small-diameter end portion 25 of the boot 23 from being lifted, and it is easy to prevent the lubricant from leaking and ensure the sealing performance of the boot 23.

  Further, the protrusion 32 of the boot 23 and the concave groove 33 of the shaft 17 have a structure in which the cross section along the axial direction forms a rectangular shape, so that the protrusion 32 of the boot 23 and the shaft have the sectional shape of the protrusion 32 and the concave groove 33. The engagement state with the 17 concave grooves 33 becomes strong.

  Therefore, it is possible to reliably prevent the boundary portion between the bellows portion 26 and the small-diameter end portion 25 of the boot 23 from being lifted, and it is easy to prevent the lubricant from leaking and ensure the sealing performance of the boot 23.

  In the above embodiment, the case where the protrusion 32 was provided on the inner peripheral surface of the small diameter end portion 25 of the boot 23 and the concave groove 33 was formed on the outer peripheral surface of the shaft 17 was illustrated. The present invention is not limited to this, and a projection can be provided on the inner peripheral surface of the large-diameter end 24 of the boot 23 and a concave groove can be formed on the outer peripheral surface of the opening 11 of the outer joint member 12. is there. Moreover, although the case where the protrusion 32 and the ditch | groove 33 were one was illustrated, not only this but a some protrusion and ditch | groove may be sufficient.

  The present invention is not limited to the above-described embodiments, and can of course be implemented in various forms without departing from the gist of the present invention. It includes the equivalent meanings recited in the claims and the equivalents recited in the claims, and all modifications within the scope.

12 outer joint member 13 inner joint member 14 torque transmission member (ball)
17 Shaft member
23 Boot 25 End (Small Diameter End)
26 Bellows 28 Boot band 32 Protrusion 33 Groove

Claims (3)

An outer joint member, and an inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member, and an outer peripheral surface of a shaft member that extends from the inner joint member. A constant velocity universal joint in which an end extending from the bellows portion of the boot is fastened and fixed by a boot band,
An annular protrusion is provided on the inner peripheral surface of the boundary portion between the bellows portion and the end portion of the boot, and an annular concave groove to be engaged with the protrusion is formed on the outer peripheral surface of the shaft member. Universal joint.   The constant velocity universal joint according to claim 1, wherein the protrusion and the groove are arranged so as to overlap the boot band in the axial direction.   The constant velocity universal joint according to claim 1, wherein the protrusion and the groove have a rectangular cross section along the axial direction.

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