JP2012207768A - Joint boot - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a joint boot having superior durability by making the position to which bending stress is applied when performing releasing from a metal die different from the position to which bending stress is applied when using the joint boot.SOLUTION: The joint boot includes a small diameter side attaching part 12 attached to a shaft, a large diameter side attaching part 14 attached to an outer case 6, and a bellows part 16 connecting both attaching parts 12, 14 to each other. On the inner periphery of the large diameter side attaching part 14, in the joint boot 10 provided with a plurality of inwardly protruded parts 24 protruded in the radial direction, the inner face of a connection part 26 connecting the protruded parts 24 to the bellows part 16 includes a flat face 28c extended in the axial direction O of the joint boot 10, a bellows side slope 28a inwardly rising in the radial direction toward the bellows part 16 from the bellows part side end part of the flat face 28c, and a protruded side slope 28b inwardly rising in the radial direction toward the protruded parts 24 from the protruded part side end of the flat face 28c.

Description

  The present invention relates to a bellows-shaped joint boot used for an automobile triport type constant velocity joint or the like.

A triport type joint is known as one of constant velocity joints used for vehicle drive shafts and the like.

  For example, as shown in FIGS. 5 and 6, the triport type constant velocity joint has three trunnions 3 having rollers 2 protruding in a direction perpendicular to the axis on one shaft 1 on the input side and the output side. And the outer case 6 provided at the end of the other shaft 5. The outer case 6 has three sliding grooves 6 a in the axial direction corresponding to the tripart 4 on the inner periphery thereof. The constant velocity joint is capable of transmitting rotational torque while allowing the shafts 1 and 5 to be angled by fitting the roller 2 of the triport 4 with the sliding groove 6a so as to be slidable in the axial direction. It is configured.

  In such a constant velocity joint, in order to prevent dust and foreign matter from entering the joint, or to keep the sealed grease, generally, the portion of the shaft 1 on the side of the triport 4 from the outer case 6 is used. A joint boot 100 having a bellows shape that can be appropriately expanded and contracted and bent so as to cover is mounted. The joint boot 100 is formed as a large-diameter side attachment portion 101 having one end portion in the axial direction fitted on the outer periphery of the outer case 6 and fixed by a fastening member 7 such as a ring-shaped band, and the other end portion is the tripart 4. Is formed as a small-diameter side mounting portion 102 fixed to the outer periphery of the side shaft 1 by a fastening member 8 such as a ring-shaped band, and the large-diameter side mounting portion 101 and the small-diameter side cylindrical portion 102 are integrally connected by a bellows portion 103. Configured. The bellows portion 103 has a shape in which a plurality of (for example, three) trough portions and crest portions including the first trough portion 105A and the first crest portion 106A are alternately arranged in order from the large-diameter side attachment portion 101 side. Is formed.

  As shown in FIG. 6, the outer case 6 is provided with three evenly arranged concave portions 6 b in the circumferential direction on the outer periphery corresponding to the arrangement of the inner peripheral sliding grooves 6 a. The outer peripheral shape is formed in a non-circular shape having an uneven shape in the circumferential direction. Therefore, the large-diameter side attachment portion 101 of the joint boot 100 attached to the outer case 6 has a noncircular shape whose inner peripheral shape corresponds to the outer peripheral shape of the outer case 6. In other words, on the inner periphery of the large-diameter side mounting portion 101, there are formed protruding portions 104 that protrude inwardly at three locations in the circumferential direction corresponding to the concave portions 6b of the outer case 6 (for example, , See Patent Document 1 below).

JP 2006-118698 A

  As described above, when the overhanging portion 104 protrudes from the inner periphery of the large-diameter side attachment portion 101, the first valley portion 105A located closest to the bellows portion 103 is expanded or contracted or bent when the bellows portion 103 is bent. For this purpose, a groove portion 107 is formed in the connecting portion between the overhanging portion 104 and the bellows portion 103 provided in the large-diameter side attachment portion 101 and is recessed outward in the radial direction as shown in FIG. The groove 107 is substantially V sandwiched between a bellows-side inclined surface 107a that rises inward in the radial direction toward the bellows portion 103 and a protruding-side inclined surface 107b that rises inward in the radial direction toward the overhanging portion 104. Since it was shaped like a letter, the following problems were found.

  That is, in the joint boot 100 having the above shape, since the groove portion 107 has an undercut shape, the large-diameter side mounting portion 101 starts from the bottom portion 107c of the groove portion 107 when the mold is removed from the large-diameter side mounting portion 101. Demold while bending outward. Further, when the joint boot 100 mounted so as to cover the portion of the shaft 1 on the side of the triport 4 from the outer case 6 is used, the connection between the large-diameter side mounting portion 101 and the bellows portion 103 is accompanied by the bending deformation of the bellows portion 103. The bent portion 107 is bent greatly starting from the bottom 107c of the groove 107 provided in the portion. That is, it has been found that bending stress acts on the bottom 107c of the groove 107 not only when the joint boot 100 is removed but also when the joint boot 100 is used, and the durability of the joint boot 100 is likely to be impaired.

  The present invention has been made in view of the above points, and in the groove portion provided in the connecting portion between the large-diameter side attachment portion and the bellows portion, a position where bending stress acts when demolding from the mold, and An object of the present invention is to provide a joint boot having excellent durability by changing the position where bending stress acts when using the joint boot.

  The joint boot according to the present invention includes a small-diameter side attaching portion attached to a shaft, a large-diameter side attaching portion attached to an outer case and having a larger diameter than the small-diameter side attaching portion, the small-diameter side attaching portion, and the large-diameter A joint boot provided with a plurality of bellows portions extending inward in the radial direction on an inner periphery of the large-diameter side attachment portion. The inner surface of the connecting portion that connects the projecting portion and the bellows portion rises inward in the radial direction from the flat surface extending in the axial direction of the joint boot to the bellows portion from the bellows side end of the flat surface. It has a bellows-side inclined surface and a protruding-side inclined surface that rises inward in the radial direction from the end of the flat surface toward the protruding portion.

  In the joint boot according to the present invention, a flat surface extending in the axial direction of the joint boot, and a bellows portion side of the flat surface on the inner surface of the connecting portion connecting the projecting portion and the bellows portion provided in the large-diameter side attachment portion A bellows-side inclined surface that rises inward in the radial direction as it goes from the end to the bellows portion, and a protruding-side inclined surface that rises inward in the radial direction from the end portion of the flat surface to the overhanging portion are provided As a result, bending stress acts on the boundary between the overhanging inclined surface and the flat surface during demolding, and on the boundary between the bellows inclined surface and the flat surface during use, at different positions. Excellent in properties.

  Further, in the joint boot according to the present invention, the overhanging inclined surface may be provided with an inclination angle with respect to the radial direction of 30 ° or more and 60 ° or less, whereby the mold is pulled out from the joint boot. Thus, the slope of the overhanging inclined surface can be gently provided, and the mold can be easily removed.

  Further, in the joint boot according to the present invention, the large-diameter side attachment portion has a ratio y / x of the thickness y of the overhanging portion to the wall thickness x other than the overhanging portion of 1.9 or more and 3.2 or less. May be provided.

  In the present invention, it is possible to improve the durability of the joint boot in which the inner periphery of the connecting portion that connects the large-diameter side attaching portion and the bellows portion is depressed radially outward.

It is sectional drawing of the joint boot which concerns on one Embodiment of this invention. It is the front view which looked at the joint boot shown in FIG. 1 from the large diameter side attaching part side. It is a principal part enlarged view of FIG. It is a perspective view of the joint boot shown in FIG. It is sectional drawing which shows the triport type constant velocity joint which attached the conventional joint boot. It is a side view of the constant velocity joint shown in FIG. It is a principal part enlarged view of FIG.

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

  A joint boot 10 according to an embodiment of the present invention is a joint boot that is attached to the above-described automobile triport type constant velocity joint shown in FIGS. 5 and 6, and includes a small-diameter side mounting portion 12 on one end side, A hollow bellows integrally connecting the small-diameter side mounting portion 12 and the large-diameter side mounting portion 14, and the large-diameter side mounting portion 14 on the other end side disposed coaxially with the small-diameter side mounting portion 12. And is integrally formed by a known molding method such as injection molding.

  The small-diameter side mounting portion 12 has a short cylindrical shape that is fitted and fixed to the shaft 1 on the triport 4 side, and a fixing concave portion 18 that extends in the circumferential direction for receiving the ring-shaped fastening member 8 on the outer peripheral surface. Is provided. An annular seal protrusion 13 is provided on the entire inner periphery of the small diameter side mounting portion 12, and the seal protrusion 13 increases the surface pressure between the small diameter side mounting portion 12 and the shaft 1 to improve the sealing performance.

  The large-diameter side attachment portion 14 has a short cylindrical shape that is fitted and fixed to the outer case 6, and is arranged coaxially with the small-diameter side attachment portion 12, that is, has a common central axis O. The large-diameter mounting portion 14 is also provided with a fixing recess 20 extending in the circumferential direction for receiving the ring-shaped fastening member 7 on the outer peripheral surface. Further, an annular seal protrusion 15 is provided on the inner periphery of the large-diameter side mounting portion 14 over the entire circumference, and the surface pressure between the large-diameter side mounting portion 14 and the outer case 6 is increased in the seal protrusion 15 to improve sealing performance. Is increasing.

  The bellows portion 16 is a bellows body having a circular cross section with a difference in diameter at both ends, and forms a grease filled space therein. The bellows portion 16 includes a plurality of (for example, three) valley portions 21A, 21B, and 21C and a plurality of (for example, three) peaks including the first valley portion 21A and the first peak portion 23A in order from the large-diameter side attachment portion 14 side. The portions 23A, 23B, and 23C are alternately connected to each other, and are formed in a tapered shape having a small diameter sequentially from the large diameter side mounting portion 14 to the small diameter side mounting portion 12.

  As shown in FIG. 2, the large-diameter side mounting portion 14 has a circular outer peripheral shape, and the inner peripheral shape is a non-circular surface projecting inward at a plurality of circumferential positions (for example, three locations). It has a circular shape. As a result, the large-diameter side attachment portion 14 has an arc-shaped portion 22 disposed opposite to the arc-shaped outer peripheral surface of the outer case 6 and an overhang portion 24 fitted to the concave portion 6b of the outer case 6. They are provided alternately in the circumferential direction. In this embodiment, the ratio y / x of the wall thickness x of the arcuate portion 22 to the wall thickness of the overhang portion 24 (that is, the wall thickness of the overhang portion 24 at the most inward projecting position) y is 1.9. It is set within the range of ~ 3.2.

  A groove portion 28 that is recessed outward in the radial direction is formed inside the connecting portion 26 that connects the overhang portion 24 and the bellows portion 16 provided on the large-diameter side attachment portion 14. The bottom of the groove portion 28 forms a flat surface 28c extending along the direction of the central axis O, and a bellows-side inclined surface 28a that rises inward in the radial direction from the bellows-side end of the flat surface 28c toward the bellows portion 16 is provided. In addition, an overhanging inclined surface 28b that rises inward in the radial direction from the overhanging portion side end of the flat surface 28c toward the overhanging portion 24 is provided. As a result, a groove portion 28 including a bellows-side inclined surface 28 a, a flat surface 28 c, and an overhang-side inclined surface 28 b is provided inside the connecting portion 26.

  Here, the overhanging inclined surface 28b preferably has an inclination angle θ with respect to the radial direction r in a range of 30 ° to 60 °. When the inclination angle θ of the overhanging inclined surface 28b is smaller than 30 °, the inclination of the overhanging inclined surface 28b with respect to the direction in which the mold is pulled out from the joint boot 10 is increased, and it is difficult to remove the mold and the moldability is impaired. When θ is greater than 60 °, the length L in the direction of the central axis O of the large-diameter side attachment portion 14 is shortened, and the sealing performance with the outer case 6 is impaired.

  In the joint boot 10 of the present embodiment having the above-described configuration, radially outward to the inside of the connecting portion 26 that connects the overhanging portion 24 and the bellows portion 16 provided in the large-diameter side attachment portion 14. Since the recessed groove portion 28 is provided, not only the valley portions 21B and 21C and the mountain portions 23A, 23B and 23C but also the first valley portion 21A provided on the largest diameter side attachment portion 14 side when the bellows portion 16 is bent and deformed. Also, it will be expanded and contracted or bent, and it is possible to ensure the ease of bending.

  Further, the bottom portion of the groove portion 28 provided in the connecting portion 26 forms a flat surface 28c extending along the central axis O direction, and the bellows-side inclined surface 28a connected to the bellows portion 16 and the overhanging portion connected to the overhanging portion 24. Since the side inclined surface 28b is connected to the flat surface 28c at a different position, the joint boot 10 for releasing the mold from the groove portion 28 while bending the large-diameter side mounting portion 14 radially outward is taken out of the mold. When the joint boot 10 in which the bellows portion 16 is bent and deformed, bending stress acts at different positions, and the durability of the joint boot 10 can be improved.

DESCRIPTION OF SYMBOLS 10 ... Joint boot 12 ... Small diameter side attaching part 13 ... Sealing protrusion 14 ... Large diameter side attaching part 15 ... Sealing protrusion 16 ... Bellows part 18 ... Fixing recessed part 20 ... Fixing recessed part 21A ... 1st trough part 22 ... Arc-shaped part 23A ... 1st peak part 24 ... Overhang part 26 ... Connection part 28 ... Groove part 28a ... Bellows side inclined surface 28b ... Overhang side inclined surface 28c ... Flat surface O ... Center axis

Claims (3)

A small-diameter side attachment portion attached to the shaft, a large-diameter side attachment portion attached to the outer case and having a larger diameter than the small-diameter side attachment portion, and a bellows connecting the small-diameter side attachment portion and the large-diameter side attachment portion. In the joint boot provided with a plurality of projecting portions projecting radially inward in the inner periphery of the large-diameter side mounting portion,
The inner surface of the connecting portion that connects the projecting portion and the bellows portion is a flat surface extending in the axial direction of the joint boot, and radially inward from the bellows portion side end portion of the flat surface toward the bellows portion. A joint boot comprising: a bellows-side inclined surface that rises inward, and a protruding-side inclined surface that rises inward in the radial direction from the end of the flat surface toward the protruding portion.     The joint boot according to claim 1, wherein the overhanging inclined surface is provided with an inclination angle with respect to a radial direction of 30 ° or more and 60 ° or less.     The large-diameter side attachment portion is provided such that a ratio y / x of a thickness y of the overhanging portion to a thickness x other than the overhanging portion is 1.9 or more and 3.2 or less. The joint boot according to claim 1 or 2.

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