JP2016035277A - Constant-velocity universal joint boot and constant-velocity universal joint - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate attaching a boot band to a band groove without degrading a boot band detachment prevention function.SOLUTION: A constant-velocity universal joint boot 40 comprises: a bellows portion 42; a small-diameter attachment portion 44 provided in a small-diameter-side end portion of the bellows portion 42; and a large-diameter attachment portion 46 provided in a large-diameter-side end portion of the bellows portion 42, a band groove 48 being formed on an outer circumference of each of the attachment portions 44 and 46, the constant-velocity universal joint boot 40 being configured so that a protrusion portion 50 rising from an outer end portion of the band groove 48 toward an outside diameter is provided, and an external shape of the protrusion portion 50 is a circular shape about a center decentralized from a center of a cylindrical bottom surface 48a of the band groove 48.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a constant velocity universal joint boot and a constant velocity universal joint.

  The constant velocity universal joint is used to transmit power by connecting the first rotating shaft and the second rotating shaft, and the fixed constant velocity universal joint capable of only angular displacement and axial displacement (plunging) It can also be broadly classified as a slidable motion type constant velocity universal joint. In either case, the inner joint member connected to the second rotating shaft (shaft), the outer joint member connected to the first rotating shaft, and the inner joint member and the outer joint member are interposed to transmit torque. It is comprised with a torque transmission member. The torque transmission member consists of balls and rollers as rolling elements and other multiple members, and the torque transmission member is interposed between the inner joint member and the outer joint member, so that the angular displacement and axial displacement between them are smooth. To do. In order to perform such lubrication of the torque transmission member and lubrication between the members that move relative to the displacement, the constant velocity universal joint is filled with a lubricant such as grease.

  In order to prevent leakage of the lubricant to the outside and to prevent foreign matter from entering from the outside, the constant velocity universal joint is generally used with a boot. This constant velocity universal joint boot includes a bellows-shaped bent portion (bellows portion), a large-diameter attachment portion provided at the large-diameter side end portion of the bellows portion, and a small-diameter attachment portion provided at the small-diameter side end portion of the bellows portion. It consists of. Fit the large-diameter mounting part to the boot mounting part provided at the open end of the outer joint member of the constant velocity universal joint, and the small-diameter mounting part to the boot mounting part provided on the shaft connected to the inner joint member of the constant velocity universal joint. Fit and fasten each with a boot band.

  Constant velocity universal joints have a function to rotate while taking an operating angle, and in order to ensure flexibility to follow the behavior, constant velocity universal joint boots are devised in terms of material and shape. ing. Conventionally, rubber boots such as chloroprene rubber have been used, but resin boots using a thermoplastic elastomer material that is superior in durability compared to rubber boots have been widely used.

  Regardless of whether it is a rubber boot or a resin boot, the boot is fixed to the outer joint member or shaft by attaching a boot band to the cylindrical band groove formed on the outer periphery of the large-diameter mounting portion or small-diameter mounting portion of the boot. Then, the boot band is contracted to tighten the large-diameter mounting portion or the small-diameter mounting portion of the boot. In addition, the side wall on the boot end face side of the band groove is expected to have an action of restraining the boot band in the band groove from coming off in the axial direction. The side wall on the boot end face side is formed by a protrusion that rises from the bottom surface of the band groove to the outer diameter side. As the aspect of the protrusion, a flange-like one that is continuous in the circumferential direction (see FIG. 5), There is known one in which a plurality of independent protrusions are equally arranged in the circumferential direction (see FIGS. 6 and 7) (see Patent Document 1).

  FIG. 5 shows an example in which a flange-shaped projecting portion 150 concentric with the small-diameter mounting portion 144 of the boot is provided, FIG. 6 shows an example in which four projecting portions 150 are equally arranged in the circumferential direction, and FIG. 7 shows three projecting portions. An example in which 150 is equally distributed in the circumferential direction is shown. As shown in FIG. 5, the flange-like protrusion 150 is continuously present over the entire circumference, so that not only the side wall 148b on the bellows part side but also the side wall 148c on the boot end face side is continuously present over the entire circumference. To do. Therefore, once the boot band 152 is attached to the band groove 148, it can be prevented from being displaced in the axial direction or coming off the band groove 148.

  5A shows a state before the boot band 152 is attached to the band groove 148, and FIG. 5B is an end view of the small-diameter attaching portion 144 shown in FIG. 5A. Shows a state before the boot band 152 is attached to the band groove 148 and tightened. The relationship between FIG. 6 (a) and FIG. 6 (b) is similar to the relationship between FIG. 5 (a) and FIG. 5 (b), and the relationship between FIG. 7 (a) and FIG. Since it is the same as the relationship of the above-mentioned FIG. 5 (a) and FIG.5 (b) and only the number of the protrusion parts 150 differs, description is abbreviate | omitted. The symbol φA represents the outer diameter of the bottom surface 148a of the band groove 148, and the symbol t2 represents the height of the protruding portion 150 from the bottom surface 148a.

8 to 10 show typical examples of existing boot bands. In the figure, the symbol D ₁ represents the inner diameter before tightening, and the symbol D ₂ represents the inner diameter after tightening.

The boot band shown in FIG. 8 is constituted by a cylindrical annular member. Usually, the annular member is plastically deformed to reduce the diameter (D ₁ → D ₂ ) so as to obtain a tightening force.

The boot band shown in FIG. 9 is provided with a plurality of claws and holes at both ends of the belt member, and the diameter is reduced (D ₁ → D ₂ ) by hooking holes on different claws before and after tightening. A tightening force is obtained.

The boot band shown in FIG. 10 is designed to obtain a tightening force by applying plastic deformation to a portion called an Ω portion and reducing the diameter (D ₁ → D ₂ ).

To obtain the binding force necessary to seal ensuring, it is desirable to be able to reduce the internal diameter D ₂ after tightening of the boot band. In the case of the boot band shown in FIG. 10, since the maximum inner diameter difference (D ₁ −D ₂ ) before and after tightening is determined by the circumferential width of the Ω portion, the inner diameter D ₁ before tightening is set smaller. It is desirable. Even if the circumferential width of the Ω part is designed to be larger than the appropriate dimension in order to increase the maximum inner diameter difference (D ₁ -D ₂ ), the Ω part is temporarily increased to the limit due to insufficient rigidity of the Ω part. will also spread again tightened, it is difficult to maintain small inner diameter D ₂ after tightening. On the other hand, if the boot band as shown in FIGS. 8 and 9, may also be designed large before the inner diameter D ₁ clamped against the inner diameter D ₂ after tightening, when too large, the mounting of the band groove easily On the other hand, dropouts are more likely to occur. Furthermore, in the tightening process, the workability is reduced because of the large amount of movement until the tightening is completed. Accordingly, even in a boot band 8 and 9, it is desirable to set a small inner diameter D ₁ of the front fastening.

JP 2002-213484 A

  In patent document 1, the said protrusion part is arrange | positioned in three places (odd number) of the circumferential direction, and the circumferential direction length of the protrusion part is set so that a center angle may be 90 degrees or less. However, this structure is troublesome because when the boot band is small in inner diameter before tightening, the boot band must be tilted with respect to the band groove when the boot band is fitted into the band groove. Is required, and workability is poor.

  Or, even if you try to install the boot band obliquely with respect to one of the plurality of protrusions, there will be a region where other protrusions and the boot band interfere with each other. Is limited depending on the height of the protrusion. When the height of the protruding portion is high, the inner diameter of the boot band before tightening must be increased, which may affect the diameter reduction of the boot band, in other words, the inner diameter difference before and after tightening. On the other hand, if the height of the projecting portion is lowered in order to set the inner diameter dimension before tightening of the boot band, the ability to prevent the boot band from coming off axially decreases.

  In addition, in the technology of Patent Document 1 or earlier, such as a flange-like protrusion or a four-protrusion part on the circumference, even if the boot band is inclined and mounted, the larger boot band is tightened. The previous inner diameter dimension is necessary, or the height of the protruding portion needs to be set smaller.

  Therefore, an object of the present invention is to make it easy to attach a boot band to a band groove without impairing the boot band retaining function.

In order to achieve the above object, the present invention includes a bellows portion, a small diameter attachment portion provided at a small diameter side end portion of the bellows portion, and a large diameter attachment portion provided at a large diameter side end portion of the bellows portion. In the constant velocity universal joint boot in which a band groove is formed on the outer periphery of the small-diameter mounting portion and / or the large-diameter mounting portion, a protrusion rising from the outer end of the band groove to the outer diameter side is provided, and The outer shape of the projecting portion is a circular shape having a center decentered from the center of the cylindrical bottom surface of the band groove.
The small-diameter mounting portion and / or the large-diameter mounting portion means a small-diameter mounting portion, a large-diameter mounting portion, or both a small-diameter mounting portion and a large-diameter mounting portion.

  Here, the outer shape of the protrusion does not necessarily have to be continuous, and may be a plurality of protrusions that fall within the range of a virtual circle. In addition, the simple attachment portion includes both the small diameter attachment portion provided at the small diameter side end portion of the bellows portion and the large diameter attachment portion provided at the large diameter end portion of the bellows portion.

According to the present invention, it is easy to attach the boot band to the band groove of the boot, and the ability to prevent the axial drop-out after the installation is excellent.
Furthermore, the inner diameter dimension (D ₁ ) before tightening of the boot band can be set small, which works favorably for securing the tightening force of the boot band, in other words, the amount of diameter reduction (D ₁ -D ₂ ) before and after tightening.

FIG. 1A shows a small-diameter mounting portion at the small-diameter side end of the boot of the first embodiment, FIG. 1A shows a front view, FIG. 1B shows an end view, and FIG. 1C shows a state after wearing a boot band (before tightening). Is a front view similar to FIG. The small diameter attaching part of the small diameter side edge part of the boot of 2nd Example is shown, (a) is a front view, (b) is an end view. The small diameter attaching part of the small diameter side edge part of the boot of 3rd Example is shown, (a) is a front view, (b) is an end view. It is a partially broken front view of the common constant velocity universal joint of the state which mounted | wore with the boot. FIG. 5A shows a small-diameter mounting portion at a small-diameter side end portion of a boot according to the prior art, FIG. 5A shows a front view, FIG. 5B shows an end view, and FIG. 5C shows a state after wearing a boot band (before tightening). FIG. The small diameter attaching part of the small diameter side edge part of the boot by another prior art is shown, (a) is a front view, (b) is an end view. Furthermore, the small diameter attaching part of the small diameter side edge part of the boot by another prior art is shown, (a) is a front view, (b) is an end view. It is a front view of a boot band, (a) shows before tightening, (b) shows after tightening. It is a front view of another bootband, Comprising: (a) shows before fastening, (b) shows after fastening. It is a front view of another boot band, (a) is before tightening, (b) shows after tightening.

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

  First, the overall configuration of a constant velocity universal joint equipped with boots will be described. The constant velocity universal joint, as already mentioned, can be fixed type constant velocity universal joints (Zepper type, undercut free type, etc.) that can only be angularly displaced, as well as angular displacement (plunging) as well as angular displacement. Although it is roughly classified into sliding type constant velocity universal joints (double offset type, tripod type, cross groove type, etc.), the present invention is applicable to any constant velocity universal joint as long as it uses boots. Can do.

  The constant velocity universal joint illustrated in FIG. 4 is a fixed type constant velocity universal joint, and includes an inner joint member 10, an outer joint member 20, a ball 30 that is a torque transmission member, and a cage 32. It is attached.

The inner joint member 10 has a spline (or serration, hereinafter the same) hole 14 that is connected to the second rotating shaft (shaft) 12 so that torque can be transmitted, and a plurality of axially extending outer peripheral surfaces 16 extend in the axial direction. Are formed at equal intervals in the circumferential direction.
On the outer periphery of the shaft 12, an annular boot mounting portion 13 for attaching the small diameter mounting portion 44 at the small diameter side end portion of the boot 40 is formed.

The outer joint member 20 includes a cup portion 22 and a first rotating shaft 24, and a second rotating shaft (shaft) (not shown) capable of transmitting torque with a spline shaft formed on the first rotating shaft 24. It comes to connect. A plurality of ball grooves 28 extending in the axial direction are formed at equal intervals in the circumferential direction on the spherical inner peripheral surface 26 of the cup portion 22.
An annular boot mounting portion 23 for attaching a large diameter attachment portion 46 at the large diameter side end portion of the boot 40 is provided on the outer periphery of the cup portion 22 on the opening end portion side.

  The inner joint member 10 is accommodated in the cup portion 22 of the outer joint member 20, and a cage 32 is interposed between the inner joint member 10 and the outer joint member 20. The ball groove 18 of the inner joint member 10 and the ball groove 28 of the outer joint member 20 form a pair, and a ball 30 as a torque transmission member is disposed between each pair of ball grooves 18, 28. The cage 32 has pockets 34 arranged at predetermined intervals in the circumferential direction, and the balls 30 are accommodated in the pockets 34 to hold all the balls 30 in the same plane.

  The spherical inner peripheral surface 36 of the cage 32 is in spherical contact with the outer peripheral surface 16 of the inner joint member 10, and the spherical outer peripheral surface 38 is in spherical contact with the inner peripheral surface 26 of the outer joint member 20. The joint member 20 can take an angular displacement (operation angle) around the joint center. The center of curvature of the spherical inner peripheral surface 36 of the cage 32 and the center of curvature of the spherical outer peripheral surface 38 may be offset equidistantly on the opposite side in the axial direction across the joint center.

  FIG. 4 shows a state of zero angular displacement in which the central axis of the inner joint member 10 and the central axis of the outer joint member 20 are in a straight line. Even when the joint takes an angular displacement (operating angle), it is already described. As shown, all the balls 30 are held in the same plane by the cage 32. As a result, the lengths of the perpendiculars dropped from the center of the ball 30 to the central axes of the inner joint member 10 and the outer joint member 20 are equal, and the angular velocity of the ball 30 during joint rotation is always constant.

  The boot 40 includes a bellows portion 42, a small diameter attachment portion 44 provided at the small diameter side end portion of the bellows portion 42, and a large diameter attachment portion 46 provided at the large diameter side end portion of the bellows portion 42. The small-diameter mounting portion 44 is attached to the boot mounting portion 13 of the shaft 12, and the large-diameter mounting portion 46 at the large-diameter side end is mounted to the boot mounting portion 23 of the outer joint member 20.

  FIG. 1 shows a first embodiment of a boot. The small diameter attachment portion 44 on the small diameter end portion side of the boot 40 will be described with reference to FIG. 1, but the same applies to the large diameter attachment portion 46 on the large diameter end portion side.

  An annular band groove 48 is formed on the outer periphery of the small-diameter mounting portion 44. The bottom surface 48a of the band groove 48 has a cylindrical shape, and the side walls 48b and 48c rise in the radial direction from both axial ends of the bottom surface 48a. The boot band 52 is axially positioned by these side walls 48b and 48c. That is, as shown in FIG. 1C, once the boot band 52 is mounted in the band groove 48, the axial movement of the boot band 52 is restricted by the side walls 48b and 48c. Specifically, the side wall 48b prevents the boot band 52 from moving inward in the axial direction (left side in FIG. 1C), and the side wall 48c extends outward in the axial direction of the boot band 52 (in FIG. 1C). Stop moving to the right). In particular, the side wall 48c on the boot end face side plays a role of preventing the boot band 52 from slipping outward in the axial direction and coming off the band groove 48.

  As shown in FIG. 1A, among the side walls 48b and 48c of the band groove 48, the side wall 48b on the bellows portion 42 side is continuously present over the entire circumference, whereas the side wall 48c on the boot end surface side is There is no partial area in the circumferential direction. As can be seen from FIG. 1B, the boot end face side wall 48c is formed by a protrusion 50 protruding radially outward from the bottom surface 48a, and the outline of the protrusion 50 is circular (outer diameter φB). The center of the circle (outer diameter φB) is eccentric from the center of the cylindrical bottom surface 48 a of the band groove 48. The symbol t1 represents the amount of eccentricity. As a result, the height t2 of the protrusion 50 from the bottom surface 48a is the highest at the center of the outer diameter φB of the protrusion 50 from the center of the bottom surface 48a (the uppermost part in FIG. 1B) (t2 = φB−φA), it gradually decreases as it moves away from it, and finally merges with the bottom surface 48a. In this case, geometrically, the height t2 becomes 0 at one point in the circumferential direction, that is, at the lowermost part in FIG.

  In the second embodiment shown in FIG. 2, the height t2 from the bottom surface 48a of the band groove 48 gradually changes in the circumferential direction, but the protruding portion 50 exists over the entire circumference. However, since the amount of eccentricity is smaller than that in the first embodiment, the maximum value of the height t2 from the bottom surface 48a is lower than that in the first embodiment. Since the outer diameter φB of the protrusion 50 is the same as that in the embodiment of FIG. 1, the mounting property of the boot band 52 is the same.

  The height t2 of the protrusion 50 from the bottom surface 48a of the band groove 48 changes according to the amount of eccentricity between the center of the circle drawn by the outer shape of the protrusion 50 and the center of the bottom surface 48a of the band groove 48. Then, when the outer diameter φB of the protrusion 50 is constant, the maximum value of the height t2 of the protrusion 50 is increased or the maximum value of the height t2 of the protrusion 50 is slightly reduced, but the protrusion 50 (side wall) 48c) should be present over the entire circumference or should be selected in consideration of various conditions.

When the outer diameter of the bottom surface 48a of the band groove 48 is φA, the outer diameter of the protrusion 50 is φB, the amount of eccentricity is t1, and the maximum height of the protrusion 50 is t2.
φB> φA and t2 ≧ 2 × t1
Is preferable. Furthermore, t1 = t2 / 2 is desirable.

Further, the inner diameter φD ₁ (see FIGS. 8 to 10) of the boot band 52 to be attached before tightening is:
φD ₁ > φA
But preferably,
φD ₁ ≧ φB
It is. More preferably,
φA + 4mm ≧ φD _1> φB
It is. Although the setting (φD ₁ > (φA + 4 mm)) where the inner diameter φD ₁ before tightening of the boot band 52 exceeds (φA + 4 mm) is possible, the design of the boot band 52 is restricted and the eccentricity t1 in the present invention And the intention of setting the protrusion height t2 is not sufficiently exhibited.

  Note that the outer shape of the protruding portion 50 viewed in a plane perpendicular to the central axis of the small-diameter mounting portion 44 is not necessarily a perfect circle as long as it is within a circular range in which the center is eccentric. For example, as in the third embodiment shown in FIG. 3, a plurality of protrusions 50A and 50B having different heights, each having a circle indicated by a two-dot chain line as a circumscribed circle, may be arranged.

  In addition, the cross-sectional shape of the protruding portion 50 as viewed in the vertical cross-section of the small-diameter mounting portion 44 is selected from a rectangular, triangular, semi-circular or other arbitrary shape in consideration of the manufacturing (molding) surface of the boot 40. Can be adopted. Also, the thickness is not particularly limited, but is practically about 0.5 mm to 3 mm.

When the boot band is mounted with the conventional projecting portion 150 (see FIGS. 5 to 7), the inner diameter φD ₁ of the boot band before tightening is the outer diameter φA of the bottom surface 148a of the boot band groove 148 + the height of the projecting portion. A dimension of t2 × 2 or more is required. However, when t1 = t2 / 2, which is the most desirable case of the present invention (FIG. 1), the outer diameter φA of the bottom surface 48a of the band groove 48 of the boot 40 + the protruding portion height t2 = the inner diameter not less than the protruding portion outer diameter φB. A boot band having φD ₁ can be mounted.

  Further, if the operation is to attach the boot band 52 obliquely from the phase of the protruding portion 50 and then to install the phase opposite to 180 degrees (the phase without the protruding portion 50), the inner diameter dimension of the boot band 52 is changed. It is also possible to set a smaller value. This is more advantageous than the method in which the boot band is obliquely attached to the cylindrical portion provided with the three protruding portions 150 described in Patent Document 1.

  Although it is desired to increase the protrusion height t2 from the standpoint of preventing the bootband from falling off, according to the embodiment, the protrusion height t2 that is higher than the conventional example with respect to the inner diameter before the bootband 52 is tightened. Can be set.

The boot 40 according to the embodiment is more effective when a boot band designed so that the state before tightening is circular and the diameter reduction amount before and after tightening (D ₁ -D ₂ ) is not so large is used. For example, a boot band (FIG. 10) having a structure in which a portion called an Ω portion is subjected to plastic deformation to reduce the diameter, or a plurality of claws and holes are provided at both ends of the belt member, and holes are formed in different claws before and after tightening. A boot band having a structure in which the diameter is reduced (D ₁ → D ₂ ) by hooking (FIG. 9) or a boot band having a structure in which the annular member is plastically deformed to reduce the diameter (D ₁ → D ₂ ) (FIG. 8). Etc. A boot band having a reduced diameter (D ₁ -D ₂ ) before and after tightening of the inner diameter of the boot band is 4 mm or less, more preferably 3 mm or less. When this diameter difference exceeds 4 mm, the effect of the present invention becomes poor.

  The material of the boot 40 is not particularly limited. However, according to the present invention, a material having a tendency that the wearability of the boot band 52 tends to be disadvantageous due to high rigidity, for example, a thermoplastic polyester elastomer having a hardness by a type D durometer (JIS K 6253) of 35 or more is used as the material. If applied to a resin boot, the effect becomes even more remarkable.

  The boot 40 is attached by the following procedure. As a premise, the shaft 12 is passed through the boot 40 when the constant velocity universal joint is assembled. Further, the case where the small diameter attachment portion 44 on the small diameter end portion side is attached to the boot mounting portion 13 of the shaft 12 will be described, but the case where the large diameter attachment portion 46 on the large diameter end portion side is attached to the boot attachment portion 23 of the outer joint member 20. The same is true for.

First, the small-diameter mounting portion 44 at the small-diameter side end of the boot 40 is aligned with the boot mounting portion 13 of the shaft 12, and the inner periphery of the small-diameter mounting portion 44 is fitted to the boot mounting portion 13.
Next, the boot band 52 is attached to the band groove 48 of the small diameter attachment portion 44. At that time, the boot band 52 is aligned with the protruding portion 50 of the small-diameter mounting portion 44 of the boot 40, and the boot band 52 is moved in the axial direction as indicated by a white arrow in FIG. Then, since there is no portion protruding from the outer shape of the protrusion 50, the boot band 52 can be smoothly attached to the band groove 48 while avoiding interference between the inner periphery of the boot band 52 and the protrusion 50.

After performing the above operation, the diameter of the boot band 52 is reduced (D ₁ → D ₂ ), and the small diameter attaching portion 44 is tightened to the inner diameter side. As a result, as shown in FIG. 4, the small-diameter mounting portion 44 is deformed and is in close contact with the boot mounting portion 13, and a good sealing property and a reliable fixing effect of the small-diameter mounting portion 44 are ensured.

  In this manner, the work of attaching the boot band 52 to the band groove 48 can be smoothly performed while setting the outer diameter φB and the height t2 of the protrusion 50 to values necessary and sufficient to prevent the boot band 52 from coming off. Thus, it is possible to achieve both the effect of preventing the fall off of the boot band 52 and the improvement in workability of the mounting work. Further, since the inner diameter dimension of the boot band 52 can be made smaller than that of the conventional product, a greater binding force can be generated, and the design freedom of the boot band 52 is increased.

  In the above description, after the small diameter mounting portion 44 of the boot 40 is fitted to the boot mounting portion 13 of the shaft 12, the boot band 52 is mounted on the band groove 48 of the small diameter mounting portion 44 and tightened. However, the boot band 52 may be mounted in advance in the band groove 48 of the small-diameter mounting portion 44 and the small-diameter mounting portion 44 with a boot band may be fitted to the boot mounting portion 13.

  It is as follows if the effect of the above-mentioned embodiment is summarized and listed.

  The constant velocity universal joint boot according to the embodiment includes a bellows portion 42, a small diameter attachment portion 44 provided at a small diameter side end portion of the bellows portion 42, and a large diameter attachment portion provided at a large diameter side end portion of the bellows portion 42. 46, and a constant velocity universal joint boot 40 having a band groove 48 formed on the outer periphery of the small diameter mounting portion 44 and / or the large diameter mounting portion 46, rises from the outer end of the band groove 48 to the outer diameter side. The projecting portion 50 is provided, and the outer shape of the projecting portion 50 is a circle having a center eccentric from the center of the cylindrical bottom surface 48 a of the band groove 48.

  By adopting such a configuration, when the boot band 52 is mounted in the band groove 48 of the boot 40, the interference between the inner periphery of the boot band 52 and the protrusion 50 is avoided, and the boot band 52 is smoothly banded. It can be mounted in the groove 48. Therefore, the height t2 of the protruding portion 50 is increased to reliably prevent the boot band 52 from coming off from the band groove 48, while the work of attaching the boot band 52 to the band groove 48 can be performed smoothly. In this way, it is possible to achieve both the effect of preventing the boot band 52 from falling off and the improvement in workability of the mounting work. Further, the inner diameter of the boot band 52 before tightening can be made smaller than that of the conventional product, so that a larger binding force can be generated, and the design freedom of the boot band 52 is improved.

  The protrusion 50 exists over the entire circumference of the band groove 48, and the height t <b> 2 from the bottom surface 48 a of the band groove 48 continuously changes, so that the side wall 48 c on the boot end surface side exists over the entire circumference. Therefore, it is possible to reliably prevent the boot band 52 from falling off.

  The protrusion 50 includes a plurality of protrusions 50A and 50B that are independent of each other, and the height t2 from the groove bottom 48a is within a circle having a center that is eccentric from the center of the bottom surface 48a of the band groove 48. It may change gradually. Although the case where the said circle turns into the circumscribed circle of protrusion part 50A, 50B is a typical example, as long as it falls within the range of a circle, a protrusion part does not necessarily need to touch a circle.

  Uses a resin boot made of a thermoplastic polyester elastomer that has a hardness of 35 or more according to the type D durometer stipulated in JIS K 6253. This is especially noticeable. Since the resin boot is higher in rigidity and inferior in rubber-like elasticity than the rubber boot, when the boot band 52 is mounted on the band groove 48, if the boot band 52 interferes with the protruding portion 50, the mounting workability tends to be lowered. Because.

The boot band 52 whose diameter reduction (D ₁ -D ₂ ) before and after tightening is 4 mm or less can be attached to the band groove 48. Thereby, it becomes possible to use the boot band 52 having a small inner diameter φD ₁ before tightening, and the design freedom of the boot band is increased.

  In the constant velocity universal joint using the boot 40, the small-diameter mounting portion 44 at the small-diameter side end is fitted to the shaft 12, the large-diameter mounting portion 46 at the large-diameter side end is fitted to the outer joint member 20, and the mounting portion 44, The boot band 52 is attached to the band groove 48 of 46 and fixed by tightening. Even in the constant velocity universal joint with the boot, the effect of the boot 40 can be obtained.

  The embodiment of the present invention has been described above with reference to the accompanying drawings, but the present invention is not limited to the embodiment described here and illustrated in the accompanying drawings, and the scope of the claims is defined as follows. Various modifications can be made without departing from the scope.

DESCRIPTION OF SYMBOLS 10 Inner joint member 12 Shaft 13 Boot mounting part 14 Spline hole 16 Outer peripheral surface 18 Ball groove 20 Outer joint member 22 Cup part 23 Boot mounting part 24 Stem part 26 Inner peripheral surface 28 Ball groove 30 Ball (torque transmission member)
32 Cage 34 Pocket 36 Inner peripheral surface 38 Outer peripheral surface 40 Boot 42 Bellows portion 44 Small-diameter mounting portion (small-diameter end side)
46 Large-diameter mounting part (large-diameter end side)
48 Band groove 48a Bottom surface 48b Side wall (bellows part side)
48c Side wall (Boot end face side)
50 Protruding part 52 Boot band

Claims (6)

  A bellows portion, a small diameter attachment portion provided at a small diameter side end portion of the bellows portion, and a large diameter attachment portion provided at a large diameter side end portion of the bellows portion, the small diameter attachment portion and / or the large diameter A boot for a constant velocity universal joint in which a band groove is formed on the outer periphery of the mounting portion, and a protrusion that rises from the outer end of the band groove to the outer diameter side is provided, and the outer shape of the protrusion is the cylindrical bottom surface of the band groove A constant-velocity universal joint boot characterized by having a circular shape with a center eccentric from the center.   2. The constant velocity universal joint boot according to claim 1, wherein the protruding portion exists over the entire circumference of the band groove, and a height from the bottom surface of the band groove continuously changes.   The protrusion is composed of a plurality of protrusions independent of each other, and the height from the groove bottom is gradually changed so as to fall within a circle having a center eccentric from the center of the bottom surface of the band groove. The constant velocity universal joint boot according to claim 1.   The boot for a constant velocity universal joint according to claim 1, 2, or 3, comprising a thermoplastic polyester elastomer having a hardness of 35 or more as measured by a type D durometer specified in JIS K 6253.   The boot for a constant velocity universal joint according to any one of claims 1 to 4, wherein a boot band having an inner diameter difference between before and after tightening of 4 mm or less is attached to the band groove. A constant velocity universal joint that connects the first rotary shaft and the second rotary shaft, and an inner joint member that is connected to the shaft that is the second rotary shaft so as to be able to transmit torque, and the first rotary shaft and torque transmission 6. A constant velocity universal joint according to any one of claims 1 to 5, further comprising an outer joint member that can be connected, and a torque transmission member that is interposed between the inner joint member and the outer joint member to transmit torque. The small-diameter mounting portion of the small-diameter side end of the boot is fitted to the shaft, the large-diameter mounting portion of the large-diameter side end is fitted to the outer joint member, and the boot is inserted into the band groove of the small-diameter mounting portion and the large-diameter mounting portion. A constant velocity universal joint fixed by attaching and tightening a band.

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