JP2007113706A - Joint boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the moldability of a bush fitted into a large diameter side attachment part of a boot body in a joint boot attached to an outer case having a non-circular outer periphery. <P>SOLUTION: The joint boot 10 comprises the boot body 18 having the large diameter side attachment part 12 attached to the outer case 6 side, a cylindrical small diameter side attachment part 14 attached to a shaft 1, and a bellows 16 connecting both of them integrally; and a bush 20 intervening between the outer case and the large diameter side attachment part and having a plurality of protrusions 26 on an inner peripheral part. The bush is provided with an axially projected tongue-shaped piece 58 on the end face 20B of an arc-shaped wall 28 positioned between the protrusions 26 adjacent with each other along the peripheral direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bellows-shaped joint boot mainly used for a constant velocity joint of an automobile.

  The joint of drive shafts of automobiles and industrial machines has a bellows-like joint boot that can be appropriately expanded and contracted and bent to retain the enclosed grease or prevent the entry of dust and foreign objects. It is installed. The joint boot has a cylindrical bellows structure with a caliber at both ends, and is coaxial with a large-diameter side mounting portion that is attached to the outer case of the constant velocity joint and spaced apart from the large-diameter side mounting portion. The small-diameter-side attachment portion that is disposed on the shaft and attached to the shaft, and the bellows portion that integrally connects the two, are integrally formed of an elastic material such as a thermoplastic elastomer resin.

  As the outer case, there is one having a non-circular outer peripheral shape having a plurality of concave portions in the circumferential direction. That is, there is an outer case provided with three equally-spaced recesses in the circumferential direction on the outer periphery corresponding to the three inner peripheral sliding grooves corresponding to the triport of the constant velocity joint. In order to enable attachment to such a non-circular outer case, there is a so-called two-piece type joint boot having a bush interposed between the outer case and the large-diameter side attachment portion (for example, the following patent document) 1 and 2).

In the bush, the outer peripheral surface has a circular cross section, and the inner peripheral portion is provided with a plurality of convex portions that protrude inward in the radial direction corresponding to the concave portions of the outer case and are distributed in the circumferential direction. Yes. In a bush having such a convex part, in order to prevent sink marks due to shrinkage after injection molding and to improve the sealing performance with the outer case, as described in Patent Document 2, a plurality of convex parts are provided on the convex part. A meat hole is provided.
JP-A-2005-240962 JP 2005-221078 A

  As described above, in a bush having a plurality of convex portions in the circumferential direction, particularly a bush having a plurality of hollow holes in the convex portion, it is not easy to perform injection molding without lacking the thickness. Then, an object of this invention is to provide the structure of the novel joint boot which can shape | mold this bush without lacking.

  The joint boot according to the present invention includes a cylindrical large-diameter side attachment portion attached to the outer peripheral outer case side having a plurality of recesses in the circumferential direction, a cylindrical small-diameter side attachment portion attached to the shaft, and both A boot body composed of a bellows part that is integrally connected, and an outer peripheral surface that is interposed between the outer case and the large-diameter side attachment part and is fitted into the large-diameter side attachment part has a circular cross-section, And a bush provided with a plurality of convex portions that are fitted in the concave portion in a circumferential direction on an inner peripheral portion that is fitted and fixed to the outer case, and the bushes are adjacent in the circumferential direction. A tongue-shaped piece projecting in the axial direction is provided on the end surface of the arc-shaped wall portion located between the convex portions.

  According to the present invention, by providing the tongue-shaped piece, excess molding material and air in the molding die can be released to this portion at the time of injection molding of the bush, and lack of the bush body can be prevented. it can. In particular, by providing the tongue-like piece on the arcuate wall portion located between the convex portions, the moldability of the convex portions is excellent. Further, since the tongue-like piece is provided so as to protrude in the axial direction from the end surface of the arc-shaped wall portion, it does not hinder the fitting with the large-diameter side attaching portion or the outer case.

  In the joint boot of the present invention, when the tongue-like piece has a tapered trapezoidal plate shape, the assembly workability when the bush is inserted into the large-diameter side mounting portion of the boot body is excellent.

  In the joint boot of the present invention, if the tongue-shaped piece is inclined radially inward toward the tip, the tongue-shaped piece serves as a guide when the bush is inserted into the boot body. The property can be further improved.

  In the joint boot of the present invention, the bush is an injection-molded body formed by injecting a molding material from the center in the circumferential direction of each of the convex portions, and the tongue-like piece is a periphery of each arc-shaped wall portion. It is preferable to be provided in the center of the direction. Thereby, the moldability of a convex part can be improved further.

  In the joint boot of the present invention, the convex portion includes an inner wall portion protruding in a curved shape radially inward, an arc-shaped outer wall portion constituting a part of the outer peripheral surface of the bush, and these inner wall portions. A radially extending central support wall that connects the outer wall portions at the center in the circumferential direction thereof, and left and right side support walls that connect the inner wall portion and the outer wall portion on both sides of the central support wall, thereby Four hollow holes may be provided in the convex portion side by side in the circumferential direction. In this case, it is preferable that the side support wall is inclined so as to be closer to the center support wall toward the outside. Even a convex portion having such a hollow hole configuration can eliminate molding defects and exhibit high sealing performance by providing the tongue-like piece.

  ADVANTAGE OF THE INVENTION According to this invention, the joint boot which is excellent in a moldability by preventing the lack of a bush main body at the time of injection molding can be provided.

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

  FIG. 1 is a sectional view of a joint boot 10 according to the embodiment, and FIG. 2 is an exploded view thereof. The joint boot 10 is attached to a triport type constant velocity joint for automobiles. As shown in FIG. 10, the constant velocity joint is provided at the end of a triport 4 in which three trunnions 3 each having a roller 2 on an input side shaft 1 project in a direction perpendicular to the axis, and an output side shaft 5. The outer case 6 is provided. The outer case 6 has three sliding grooves 6a in the axial direction corresponding to the triport 4 on the inner periphery thereof, and the roller 2 of the triport 4 is slid in the axial direction with respect to the sliding groove 6a. By fitting together, the constant velocity joint is configured to be able to transmit the rotational torque while allowing the shafts 1 and 5 to be angled. In the outer peripheral portion of the outer case 6, three concave portions 6b that are equally arranged in the circumferential direction corresponding to the arrangement of the sliding grooves 6a are provided, so that the outer peripheral shape of the outer case 6 is uneven in the circumferential direction. It is formed in a non-circular shape.

  The joint boot 10 includes a boot body 18 including a large-diameter side attachment portion 12 attached to the outer case 6 side, a small-diameter side attachment portion 14 attached to the shaft 1, and a bellows portion 16 integrally connecting the two, and an outer This is an assembly of the bush 20 interposed between the case 6 and the large-diameter side attachment portion 12.

  For example, the boot body 18 is formed by blow molding using a thermoplastic elastomer resin such as TPEE or TPO. The bush 20 is molded using a material softer than the boot body 18. For example, the bush 20 is molded by injection molding using a thermoplastic elastomer resin such as TPO or rubber such as chloroprene rubber.

  The large-diameter side mounting portion 12 of the boot body 18 has a short cylindrical shape having a circular cross section on the inner and outer peripheral surfaces, and a fixing recess 22 for receiving the ring-shaped fastening member 7 is formed on the outer peripheral surface. Is provided. Further, a sealing protrusion 42 is provided on the inner peripheral surface side of the fixing recess 22 over the entire periphery. The small-diameter side mounting portion 14 has a short cylindrical shape that is fitted and fixed to the shaft 1 on the triport 4 side, and a fixing concave portion 24 that extends in the circumferential direction for receiving the ring-shaped fastening member 8 on the outer peripheral surface. Is provided. The large-diameter side attachment portion 12 and the small-diameter side attachment portion 14 are arranged coaxially, that is, with a common axis O. The bellows portion 16 is a tapered bellows body formed so as to be sequentially reduced from the large-diameter side attachment portion 12 to the small-diameter side attachment portion 14, and the hollow portion serves as a grease-filled space 25.

  As shown in FIGS. 3 and 4, the bush 20 has an outer peripheral surface on which the large-diameter side mounting portion 12 is externally fitted, has a circular cross section, and an inner peripheral portion that is externally fitted and fixed to the outer case 6. A plurality of convex portions 26 to be fitted are distributed in the circumferential direction. The convex portions 26 protrude toward the radially inner side, are evenly arranged in the circumferential direction every 120 degrees, and an arc-shaped wall portion 28 is interposed between the adjacent convex portions 26. Yes.

  The convex portion 26 includes an inner wall portion 30 that protrudes inward in the radial direction and fits into the concave portion 6 b, and an arc-shaped outer wall portion 32 that constitutes a part of the outer peripheral surface of the bush 20. The central support wall 34 that connects the wall portions 30 and 32 at the center in the circumferential direction, and both wall portions 30 and 32 on both the left and right sides of the hollow portion between the inner wall portion 30 and the outer wall portion 32. A pair of left and right side support walls 36, 36 to be connected is provided. As a result, the convex portion 26 is provided with four hollow holes 38, 40, 40, 38 that are recessed in the axial direction side by side in the circumferential direction. The cavity between the inner wall portion 30 and the outer wall portion 32 is also supported by a support wall 37 that extends in the circumferential direction at the axially central portion of the bush 20 so as to intersect the central support wall 34 and the side support wall 36. As a result, the above-described hollow holes 38 and 40 are partitioned in the axial direction.

  As shown in FIG. 5, the central support wall 34 is formed so as to extend in the radial direction along the center line L from the center in the circumferential direction where the inner wall portion 30 protrudes inwardly. The side support wall 36 is not parallel to the central support wall 34 provided radially from the axis O, but is inclined. The side support wall 36 has a base portion 30a to the outer wall portion of the inner wall portion 30 such that the inner wall portion 30 is supported by the central support wall 34 and the side support walls 36, 36 at equal intervals in the circumferential direction. Is connected to the inner wall portion 30 at an intermediate position between the connecting portion 30b and the central support wall. Further, in the connecting portion, the outer side from the connecting portion is closer to the center, that is, closer to the central support wall 34 so as to cross the inner wall portion 30 substantially perpendicularly (θ = 70 ° to 110 °). So as to be inclined. Here, θ is an angle formed by the center line N of the side support wall 36 and the tangent line P on the inner peripheral surface of the inner wall portion 30 intersecting the center line N.

  As shown in FIGS. 7 and 8, a shallow rectangular annular groove 44 into which the sealing protrusion 42 of the boot body 18 is fitted is provided on the outer peripheral portion of the bush 20, and a large-diameter side mounting portion is provided. A diameter-expanded portion 46 capable of receiving 12 end faces 12A in the axial direction is formed. The enlarged diameter portion 46 has a length X in the axial direction so that the larger diameter side attachment portion 12 does not push down the enlarged diameter portion 46 as the bush 20 and the larger diameter side attachment portion 12 are fitted. It is set to be larger than the wall thickness T of the adjacent arcuate wall portion 28 to increase the rigidity in the axial direction. In addition, a tapered portion 48 having a smaller diameter toward the tip is formed on the outer peripheral portion of the bush 20 at the end on the bellows portion 16 side.

  The bush 20 is provided with a contact inner peripheral portion 50 having a smaller diameter than that of the outer case 6 over the entire circumference of the inner peripheral surface, whereby the bush 20 is configured to be tightly fitted to the outer case 6. The close contact inner peripheral portion 50 is provided with two sealing protrusions 51, 51 over the entire periphery. Further, the diameter of the bush 20 on the side opposite to the bellows portion 16 is larger than that of the outer case 6 in one end, and the diameter of the outer case 6 is increased when the bush 20 is fitted on the outer case 6. An inner peripheral portion 52 is provided over the entire inner peripheral surface. Further, a positioning projection 56 is provided on the inner peripheral surface of the bush 20 so as to fit in a circumferentially extending groove 54 provided on the outer peripheral surface of the outer case 6. Only the arc-shaped wall portion 28 extends in the circumferential direction (see FIG. 3). Further, as shown in FIG. 8, the protrusion 56 has an outer fitting region Q by the large-diameter side attachment portion 12 in the axial direction of the bush 20, that is, a region where the bush 20 and the large-diameter side attachment portion 12 are fitted. And is provided between the close contact inner peripheral portion 50 and the enlarged inner peripheral portion 52 on the inner peripheral side of the enlarged diameter portion 46.

  As shown in FIGS. 4 and 6, the bush 20 has a tongue-like piece 58 projecting integrally from the end surface of each arcuate wall portion 28 in the axial direction. The tongue-like piece 58 is provided at the center in the circumferential direction of each arcuate wall portion 28 on the bellows portion side end surface 20B of the bush 20 provided with the tapered portion 48, and has a thickness in the radial direction of the bush 20. It is formed in a slightly curved plate shape having a width in the circumferential direction. Specifically, the tongue-like piece 58 has a tapered trapezoidal shape in a plan view shown in FIG. 6, and has a plate shape having the same constant thickness as the tip of the tapered portion 48 as shown in FIGS. The tip protrudes inward in the radial direction.

  The bush 20 having the above configuration can be injection-molded using a molding die 60 shown in FIG. The mold 60 includes a first mold 61 that molds the anti-bellows-side end surface 20A of the bush 20, a second mold 62 that molds the outer peripheral surface, and a third mold 63 that molds the inner peripheral surface. And the injection port 64 is provided so that a molding material may be inject | poured from the circumferential direction center of each convex part 26 in the bellows part side end surface 20B. As shown in FIG. 4, the position of the injection port 64 is set at a connection portion 32 a with the central support wall 34 in the outer wall portion 32 of the convex portion 26. Also, a cavity 65 for molding the tongue-like piece 58 at the center in the circumferential direction of each arc-shaped wall portion 28 so that the tongue-like piece 58 becomes a weld portion of the molding material injected from these three inlets 64. Is provided. The cavity 65 is provided on the end surface 20B on the same side as the injection port 64 in order to improve the liquid flow of the molding material.

  With the molding die 60 having such a configuration, excess molding material and air in the molding die 60 can be released into the cavity 65 during injection molding, thereby preventing the bush body from being thinned. . In particular, since the injection port 64 is provided in each convex portion 26, the cavity 65 is provided in the arcuate wall portion 28 therebetween, and both are provided on the same end face 20B side, the flow of the molding material is improved, and the above-described wall removal is performed. It is excellent in the moldability of the convex part 26 which has the hole 38 and 40 structure. Further, since the tongue-shaped piece 58 has a plate shape having a predetermined width in the circumferential direction, the joining portion of the molding material injected from the injection ports 64 on both sides of the tongue-shaped piece 58 is surely placed in the tongue-shaped piece 58, that is, the cavity 65. Can be set within. Note that the tongue piece 58 itself may have a lack of thickness. As shown by a chain line 58A in FIG. 7, the tongue-like piece 58 is formed so as to protrude parallel to the axial direction during injection molding, but has a shape inclined inward due to shrinkage after injection molding.

  The bush 20 molded in this manner is fitted and mounted in the large-diameter side mounting portion 12 of the boot body 18 molded separately. At this time, the bush 20 is inserted into the large-diameter side attachment portion 12 from the bellows portion side end surface 20B, and the tongue portion 58 and the tapered portion 48 are provided on the bellows portion side end surface 20B. Excellent insertion workability. In particular, since the tongue-like piece 58 is inclined slightly inward, it is easy to insert the bush 20 into the large-diameter side mounting portion 12 in combination with the tapered trapezoidal shape. Excellent. Moreover, since the tongue piece 58 is disposed inside the joint boot 10 after the assembly, the appearance is not impaired.

  In the joint boot 10 to which the bush 20 is attached, the large-diameter side attachment portion 12 side is externally fitted to the outer case 6 and the small-diameter side attachment portion 14 is externally fitted to the shaft 1 and is fastened to the fixing recesses 22 and 24. By fastening and fixing the members 7 and 8 respectively, they are attached to the constant velocity joint as shown in FIG. At that time, since the inner diameter portion 52 of the bush 20 is guided by the outer case 6, it is easy to fit the outer case 6. Further, since the protrusion 56 on the inner peripheral portion of the bush 20 is outside the outer fitting region Q of the large-diameter side attachment portion 12 together with the enlarged inner peripheral portion 52, the tip portion 6 c of the outer case 6 protrudes from the enlarged inner peripheral portion 52. Through 56, it can be smoothly introduced into the contact inner periphery 50.

  In the assembled joint boot 10, since the convex portion 26 has the above-described thinning structure, the central support wall 34 supports the central portion of the inner wall portion 30 that has the largest radial inward extension, The side support walls 36 can be arranged so that the tightening force is made uniform on both sides as much as possible. In particular, the side support wall 36 is inclined so that it is closer to the center support wall 34 toward the outside, so that the cross-sectional area of the outer lightening hole 38 can be increased. While suppressing, the demolding property of a core can be ensured. Further, the side support wall 36 can be coupled to the inner wall portion 30 at an angle close to perpendicular, and the surface pressure exerted on the outer case 6 by the inner wall portion 30 can be made more uniform in the circumferential direction. Therefore, it is possible to make the seal surface pressure uniform in the circumferential direction as much as possible while ensuring the formability and reducing the variation in the tightening force.

  The joint boot of the present invention can be used by being attached to a joint of a drive shaft of an automobile or industrial machine, and can be suitably used particularly for a triport type constant velocity joint of an automobile.

The longitudinal cross-sectional view of the joint boot which concerns on embodiment of this invention Exploded sectional view of the joint boot FIG. 2 side view in the III direction IV side view of Fig. 2 Cross section of convex part of bush Bush main part enlarged plan view Exploded sectional view showing the assembly structure of the large-diameter side mounting part to the outer case Sectional drawing which shows the attachment state to the outer case of a large-diameter side attachment part Cross section of mold for manufacturing bushings Sectional view showing the joint boot assembled to the constant velocity joint

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shaft, 6 ... Outer case, 6b ... Recessed part, 10 ... Joint boot, 12 ... Large diameter side attaching part, 14 ... Small diameter side attaching part, 16 ... Bellows part, 18 ... Boot body, 20 ... Bush, 20B ... Bellows Part side end face, 26 ... convex part, 28 ... arc-shaped wall part, 30 ... inner wall part, 32 ... outer side wall part, 34 ... central support wall, 36 ... side support wall, 38, 40 ... lightening hole, 58 ... Tongue piece

Claims (6)

From a cylindrical large-diameter side mounting part attached to the outer peripheral outer case side having a plurality of recesses in the circumferential direction, a cylindrical small-diameter side mounting part attached to the shaft, and a bellows part integrally connecting the two The boot body and
An outer peripheral surface that is interposed between the outer case and the large-diameter side mounting portion and that fits in the large-diameter side mounting portion has a circular cross section, and an inner peripheral portion that is externally fixed to the outer case. A plurality of protrusions fitted into the recesses provided with a bush distributed in the circumferential direction,
A joint boot, wherein the bush includes a tongue-like piece projecting in an axial direction on an end surface of an arcuate wall portion positioned between the convex portions adjacent in the circumferential direction.   The joint boot according to claim 1, wherein the tongue-shaped piece has a tapered trapezoidal plate shape.   The joint boot according to claim 1, wherein a tip of the tongue-shaped piece is inclined radially inward.   The bush is an injection-molded body formed by injecting a molding material from each circumferential center of the convex portion, and the tongue-like piece is provided at the circumferential center of each arcuate wall portion. The joint boot according to any one of claims 1 to 3.   In the convex portion, the bush has an inner wall portion projecting in a radially inward direction, an arc-shaped outer wall portion constituting a part of the outer peripheral surface of the bush, and both the inner wall portion and the outer wall portion. A central support wall extending in the radial direction connected at the center in the circumferential direction, and left and right side support walls connecting the inner wall portion and the outer wall portion on both sides of the central support wall. The joint boot according to any one of claims 1 to 4, wherein one of the hollow holes is provided side by side in the circumferential direction. The joint boot according to claim 5, wherein the side support wall is inclined so as to approach the central support wall toward the outside.

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