JP2018035817A - Constant velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure sealability of a boot and to reduce costs by reducing the number of components.SOLUTION: In a constant velocity universal joint which includes a cup-shaped outer joint member having an opening portion and an inner joint member transmitting rotating torque between the outer joint member and itself via a ball while permitting the displacement of an angle, in which a small-diameter end portion 25 of a boot 23 closing the opening portion of the outer joint member is fastened and fixed to a mounting region 29 of a shaft 17 extended from the inner joint member by a boot band 28, the mounting region 29 of the shaft 17 includes a recessed groove 30 formed on an outer peripheral face of the shaft 17, and projections 31 formed at axial both sides of the recessed groove 30, and taper portions 33 gradually reduced in diameter toward a direction separating from the projections 31, are connected to recessed groove outer sides of the projections 31.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 such as grease is sealed in the internal 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 of the boot is fastened and fixed to the outer peripheral surface of the opening of the outer joint member of the constant velocity universal joint by a boot band. The other end of the boot is fastened and fixed to the outer peripheral surface of the shaft extending from the inner joint member of the constant velocity universal joint by a boot band.

JP 2009-185908 A

  By the way, the above-mentioned constant velocity universal joint operates so that the outer joint member and the shaft rotate while taking an operating angle. Therefore, in the case of a resin boot which is a hard material, the seal between the shaft and the end of the boot is used. It may be difficult to maintain the property only by tightening the boot band. For this reason, there is a possibility that the lubricant enclosed in the joint leaks from between the shaft and the end of the boot.

  Therefore, in order to ensure the sealing performance of the boot even under severe conditions, in the constant velocity universal joint disclosed in Patent Document 1, a seal member made of an O-ring is mounted on the inner peripheral surface of the boot end, and this seal member is attached to the constant velocity universal joint. The seal between the shaft and the end of the boot is ensured by closely contacting the outer peripheral surface of the shaft.

  However, when a structure in which a seal member made of an O-ring is mounted on the inner peripheral surface of the boot end as in the constant velocity universal joint disclosed in Patent Document 1, the seal member made of an O-ring is a separate part. Necessary. This increases the number of parts, leading to an increase in the cost of the constant velocity universal joint.

  Accordingly, the present invention has been proposed in view of the above-described improvements, and an object of the present invention is to provide a constant velocity universal joint capable of ensuring the sealing performance of the boot and reducing the cost by reducing the number of parts. There is.

  The constant velocity universal joint according to the present invention includes a cup-shaped outer joint member having an opening, and an inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member. The end of the boot that closes the opening of the outer joint member is fastened and fixed to the mounting portion of the shaft member that extends from the inner joint member by a boot band.

  As technical means for achieving the above-described object, in the present invention, the shaft member mounting portion includes a groove formed on the outer peripheral surface of the shaft member, and protrusions formed on both axial sides of the groove. The taper part which diameter-reduces gradually toward the direction away from a processus | protrusion is provided in the outside of the ditch | groove of at least one processus | protrusion.

  In the present invention, a taper portion that gradually decreases in diameter in a direction away from the protrusion is continuously provided on the outer side of the groove of the protrusion, so that the pressure applied to the boot by tightening the boot band is applied to the groove of the attachment site. Can concentrate. This concentration of pressure makes it easier for the protrusions to bite into the inner peripheral surface of the boot, so that the adhesiveness of the boot becomes good and the sealing performance can be improved.

  The tapered portion in the present invention preferably has a structure having an axial dimension that protrudes outward in the axial direction from the width end portion of the boot band. By adopting such a structure, it becomes easy to concentrate the pressure applied to the boot by tightening the boot band in the concave groove of the attachment site.

  The tapered portion in the present invention preferably has a structure having an inclination angle of less than 10 ° with respect to the axis. By adopting such a structure, it becomes easy to form a tapered portion having an axial dimension that protrudes outward in the axial direction from the end portion of the boot.

  The boot in the present invention preferably has a resin structure. If such a structure is adopted, even if it is a resin boot which is a hard material, it becomes easy to improve the adhesiveness of the boot.

  According to the present invention, the pressure applied to the boot by tightening the boot band can be concentrated in the concave groove of the attachment site. This concentration of pressure makes it easier for the protrusions to bite into the inner peripheral surface of the boot, thereby improving the adhesion of the boot.

  As a result, it is possible to reliably prevent the lubricant from leaking from between the shaft and the end portion of the boot, and to ensure the sealing performance of the boot. Moreover, since a conventional sealing member made of an O-ring is not required, the cost can be reduced by reducing the number of parts.

It is sectional drawing which shows the whole structure of a constant velocity universal joint in embodiment of this invention. It is a principal part expanded sectional view which shows the state which clamped and fixed the small diameter edge part of the boot of FIG. 1 to the shaft with the boot band. It is principal part expanded sectional drawing which shows the state which clamped and fixed the small diameter edge part of the boot to the shaft with the boot band in other embodiment of this invention. It is principal part expanded sectional drawing which shows the state which clamped and fixed the small diameter edge part of the boot to the shaft with the boot band in other embodiment of this invention.

  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, a double offset type, a cross groove type constant velocity universal joint incorporated in an automobile propeller shaft.

  As shown in FIG. 1, 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, torque transmission, and the like. The main part is composed of a plurality of balls 14 and a cage 15 which are members.

  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 structure in which a rubber bellows-like boot 23 is mounted is provided.

  The boot 23 is fastened and fixed by the boot band 28 to the outer peripheral surface of the shaft 17 extending from the inner joint member 13 and the large-diameter end 24 fastened and fixed to the outer peripheral surface of the opening 11 of the outer joint member 12. The small-diameter end portion 25 is connected to the large-diameter end portion 24 and the small-diameter end portion 25, 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 a resin boot, the surface hardness of the boot 23 is preferably HDD38 to HDD50. The resin boot is formed of, for example, a thermoplastic elastomer such as ester, olefin, urethane, amide, or styrene, and a composition containing the thermoplastic elastomer. In the case of a resin boot, if the surface hardness is smaller than the HDD 38, the heat resistance is lowered, the cost of the boot is increased, and the strength is reduced. Conversely, if the surface hardness is larger than the HDD 50, the fatigue, flexibility and assembly are reduced. This will cause a decrease in dexterity.

  When the boot 23 is a rubber boot, the surface hardness of the boot 41 is preferably Hs50 to Hs70, and the rubber boot is formed of, for example, chloroprene rubber or silicon rubber. In the case of a rubber boot, if the surface hardness is smaller than Hs50, the strength of the boot 41 is reduced, and conversely, if the surface hardness is larger than Hs70, the fatigue property is reduced.

  The constant velocity universal joint having the above configuration easily secures the sealing performance between the small-diameter end 25 of the boot 23 and the shaft 17 even when the resin boot 23 which is a hard material is provided. The following seal structure is provided.

  As shown in FIG. 2, the attachment portion 29 where the small-diameter end portion 25 of the boot 23 is fastened and fixed to the outer peripheral surface of the shaft 17 by the boot band 28 includes an annular groove 30 formed on the outer peripheral surface of the shaft 17, It is comprised by the cyclic | annular protrusion 31 formed in the axial direction both sides of the ditch | groove 30. As shown in FIG. On the other hand, on the inner peripheral surface of the small-diameter end portion 25 of the boot 23, a bulging portion 32 for positioning that fits into the concave groove 30 of the shaft 17 is formed.

  The constant velocity universal joint of this embodiment has a tapered portion 33 that gradually decreases in diameter in a direction away from the projection 31 on the outer side of the concave groove of the two projections 31 at the attachment portion 29 of the small diameter end portion 25 of the boot 23. It has a continuous structure.

  The taper portion 33 has an axial dimension L (for example, about 8 to 10 mm) that protrudes outward in the axial direction from the width end portion of the boot band 28. Further, the taper portion 33 has an inclination angle θ of less than 10 ° with respect to the axis when defining the axial dimension L thereof. Moreover, you may have the axial direction dimension L which protrudes on the axial direction outer side rather than the small diameter edge part 25 of the boot 23. FIG.

  By providing such a tapered portion 33, the pressure applied to the boot 23 by tightening the boot band 28 can be concentrated in the concave groove 30 of the attachment portion 29. This concentration of pressure increases the surface pressure at the protrusion 31 so that the protrusion 31 can easily bite into the inner peripheral surface of the boot 23.

  As a result, the adhesion of the boot 23 to the outer peripheral surface of the shaft 17 is improved, so that the lubricant enclosed in the joint is reliably prevented from leaking from between the shaft 17 and the small diameter end portion 25 of the boot 23. This can improve the sealing performance by the boot 23.

  In addition, since a seal member made of an O-ring, which has been used in conventional constant velocity universal joints, is unnecessary, the cost of the constant velocity universal joint can be reduced by reducing the number of parts.

  Furthermore, it is not necessary to increase the height of the protrusion 31 of the attachment site 29 in order to improve the sealing performance. As a result, since it is not necessary to increase the outer diameter of the material for manufacturing the shaft 17, the cost of the constant velocity universal joint can be avoided without increasing the material cost of the shaft 17.

  In this embodiment, the tapered portion 33 having an axial dimension L that protrudes outward in the axial direction from the small-diameter end portion 25 of the boot 23 is used to attach pressure applied to the boot 23 by tightening the boot band 28. It becomes easy to concentrate on the concave groove 30 of the part 29.

  Further, by forming the tapered portion 33 having an inclination angle θ of less than 10 ° with respect to the axis, the tapered portion 33 having an axial dimension L that protrudes outward in the axial direction from the small diameter end portion 25 of the boot 23 is formed. Easy to do.

  If the inclination angle θ of the taper portion 33 is 10 ° or more, it is difficult to form the taper portion 33 having an axial dimension L that protrudes outward in the axial direction from the small diameter end portion 25 of the boot 23.

  By adopting the seal structure as described above, it is easy to improve the adhesion of the boot 23 to the outer peripheral surface of the shaft 17 even if the boot 23 is made of a resin and is a hard material.

  In the above embodiment, the case where the tapered portions 33 are provided on the outer sides of the concave grooves of the two protrusions 31, that is, on both sides in the axial direction of the concave groove 30, is described, but the present invention is not limited to this, The taper portion 33 may be provided on the outer side of the concave groove of one protrusion 31, that is, on one side in the axial direction of the concave groove 39.

  FIG. 3 illustrates a case where the tapered portion 33 is provided on one axial side (the left side in the drawing) of the concave groove 30. In this case, the one axial side (the right side in the figure) of the concave groove 30 is a cylindrical portion 34 that is flat in the axial direction. FIG. 4 illustrates a case where the tapered portion 33 is provided on one axial side (the right side in the drawing) of the concave groove 30. In this case, one axial side (the left side in the figure) of the groove 30 is a cylindrical portion 34 that is flat in the axial direction.

  In any embodiment, the pressure applied to the boot 2 by tightening the boot band 28 can be concentrated in the concave groove 30 of the attachment portion 29. Due to the concentration of pressure, one protrusion 31 (the protrusion on the left side in the embodiment shown in FIG. 3 and the protrusion on the right side in the embodiment shown in FIG. 4) easily bites into the inner peripheral surface of the boot 23.

  As a result, the adhesiveness of the boot 23 to the outer peripheral surface of the shaft 17 is improved, so that the lubricant enclosed in the joint is reliably prevented from leaking from between the shaft 17 and the small diameter end portion 25 of the boot 23. It is possible to improve the sealing performance.

  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.

DESCRIPTION OF SYMBOLS 11 Opening part 12 Outer joint member 13 Inner joint member 14 Torque transmission member (ball)
17 Shaft member
23 Boot 25 End (Small Diameter End)
28 Boot band 29 Attachment part 30 Groove 31 Projection 33 Tapered portion L Axial dimension θ Inclination angle

Claims (4)

A cup-shaped outer joint member having an opening, and an inner joint member that transmits rotational torque while allowing angular displacement between the outer joint member and the outer joint member, and opening the outer joint member A constant velocity universal joint in which an end portion of a boot that closes a portion is fastened and fixed to a mounting portion of a shaft member extending from the inner joint member by a boot band,
The mounting portion of the shaft member includes a recessed groove formed on the outer peripheral surface of the shaft member, and protrusions formed on both sides in the axial direction of the recessed groove, and at least one of the protrusions on the outer side of the recessed groove from the protrusion. A constant velocity universal joint characterized in that a tapered portion that gradually decreases in diameter toward a separating direction is provided continuously.   The constant velocity universal joint according to claim 1, wherein the tapered portion has an axial dimension that protrudes outward in an axial direction from a width end portion of the boot band.   The constant velocity universal joint according to claim 1, wherein the tapered portion has an inclination angle of less than 10 ° with respect to the axis.   The constant velocity universal joint according to any one of claims 1 to 3, wherein the boot is made of resin.

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