JP2007321923A - Boot for universal coupling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a first trough part on the largest diameter side from being bitten between a rotating shaft and a shoulder part of an outer ring of a universal coupling when the angular displacement of the universal coupling becomes large. <P>SOLUTION: A boot comprises a bellows part 11, a large diameter mounting part 12 formed at one end, and a small diameter mounting part 13 formed at the other end. The large diameter mounting part 12 is fitted to the outer peripheral surface of an outer ring 21 of the universal coupling 2, and the small diameter mounting part 13 is fitted to the outer peripheral surface of the rotating shaft 22 provided in an angularly displaceable manner with respect to the outer ring 21. A projecting part 14 abutting on the shoulder part 21a of the outer ring 21 is formed on the inner surface on the largest diameter mounting part 12 side in the bellows part 11, and a slant face part 15 rises in conical surface shape from the projecting part 14 toward the first trough part 114 on the largest diameter mounting part 12 side out of trough parts of the bellows part 11. A rising angle β is 60-70°. Consequently, even if the outer peripheral surface of the rotating shaft 22 presses the inner surface of the first trough part 114 when the rotating shaft 22 is angularly displaced with respect to the outer ring 21, the first trough part 114 is hardly deformed in a falling direction of the slant face part 15. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a boot that is mounted on a universal joint such as a CVT joint or a PTJ joint in an automobile and seals the universal joint.

  One type of universal joint in an automobile drive shaft or the like is called a PJT joint. As is well known, this PJT joint is provided at the shaft end of one rotating shaft, and an outer ring in which three roller guide grooves extending in the axial direction on the inner peripheral surface are formed at equal intervals in the circumferential direction. And three roller shafts provided at the shaft end of the other rotating shaft at substantially equal intervals in the circumferential direction so as to extend in the radial direction, and to each roller shaft so as to be swingable. And a roller inserted in the roller guide groove so as to be capable of rolling, and enables angular displacement and axial displacement of one rotary shaft and the other rotary shaft, and torque between the two rotary shafts. It communicates.

  This type of PJT joint usually has a gap between the outer ring and the other rotating shaft in order to prevent the grease for lubrication filled inside from flowing out to the outside or to prevent external foreign matter from entering the inside. Used while sealed with boots.

  FIG. 4 is a cross-sectional view of the boot according to the related art, and FIG. 5 is a cross-sectional view illustrating a state in which the boot is deformed by the angular displacement of the rotation shaft from the state of FIG.

The boot 100 shown in FIG. 4 is formed of a rubber-like elastic material or the like, and has three crests 101a, 101b, 101c and three troughs 101d, 101e, 101f extending in the circumferential direction in the axial direction. The bellows portions 101 that are alternately stretchable and deformable, a large-diameter attachment portion 102 formed at one end of the bellows portion 101, and a small-diameter attachment portion 103 formed at the other end of the bellows portion 101 are included. (See, for example, Patent Document 1 below).
Japanese Utility Model Publication No. 63-74521

  As shown in FIG. 5, the boot 100 has a metal fastening band on an outer peripheral surface of an end of an outer ring 201 in which a large-diameter mounting portion 102 is formed on one rotating shaft (not shown) of the constant velocity joint 200. The other rotary shaft is fixedly fastened by 104 and the small-diameter mounting portion 103 is provided so as to be angularly displaceable with respect to the axis of the outer ring 201 via the above-described roller bearing mechanism inside the outer ring 201. It is fastened and fixed to the outer peripheral surface of 202 by another metal fastening band 105.

  Since this type of boot 100 is rotated together with the outer ring 201 and the rotating shaft 202, as shown in FIG. 5, when the rotating shaft 202 is angularly displaced with respect to the axial center of the outer ring 201, in a half cycle of rotation. The deformation in which the bellows portion 101 is stretched and contracted in another half cycle is repeated. When the constant velocity joint 200 is a PJT joint as described above, the PJT joint is configured such that the roller slides in the outer ring 201 in the axial direction along each roller guide groove, so that the rotating shaft 202 is Since the angular displacement is possible at a high angle, on the side where the boot 100 is contracted, the first trough portion 101d on the side of the largest diameter mounting portion 102 in the bellows portion 101 is the outer ring 201 as shown in FIG. There is a problem that it is likely to be caught between the shoulder portion 201a and the rotary shaft 202.

  According to the inventor's research, the conventional boot 100 has the slope portion 101g on the large diameter attachment portion 102 side in the first valley portion 101d of the bellows portion 101, in other words, the largest diameter attachment portion in the bellows portion 101. Since the rising angle α of the inclined surface portion 101g formed in the inner surface on the 102 side and coming into contact with the shoulder portion 201a of the outer ring 201 rises in a conical shape from the annular protrusion 101h is greatly reduced to about 50 °, the outer ring 201 When the first trough 101d is pressed in the radial direction by the rotating shaft 202 that is angularly displaced, the annular protrusion 101h that has been on the shoulder 201a of the outer ring 201 is first radially moved through the inclined surface 101g. Is pushed out of the shoulder 201a. When the rotary shaft 202 is further angularly displaced in this state, the first valley portion 101d is deformed so that the slope portion 101g that has lost support by the annular protrusion 101h further falls, and the shoulder portion 201a of the outer ring 201 is deformed. And the rotating shaft 202 is caught.

  The present invention has been made in view of the above points, and the technical problem is that the bellows portion of the boot is contracted when the angular displacement of the universal joint increases. It is to effectively prevent the valley portion on the largest diameter side from being caught between the shoulder portion of the outer ring of the universal joint and the rotating shaft.

  As means for effectively solving the above technical problem, a universal joint boot according to the present invention includes a bellows portion in which crest portions and trough portions extending in the circumferential direction are alternately formed in the axial direction, and the bellows portion. A large-diameter mounting portion formed at one end of the accordion portion and a small-diameter mounting portion formed at the other end of the bellows portion, and the large-diameter mounting portion is fitted to the outer peripheral surface of the outer ring of the universal joint. Is fitted on the outer peripheral surface of the rotary shaft provided so as to be angularly displaceable with respect to the outer ring, and a protrusion is formed on the inner surface of the bellows portion on the side of the largest diameter mounting portion that contacts the shoulder portion of the outer ring. The slope portion rises in a conical shape from the protrusion to the inner peripheral side toward the first valley portion on the largest diameter mounting portion side of the valley portion of the bellows portion, and the rising angle of the inner surface of the slope portion is It is 60-70 degrees.

  According to the universal joint boot according to the present invention, the inclined surface on the large-diameter mounting portion side of the first valley portion in the bellows portion is formed at a rising angle of 60 to 70 °, so that the rotational axis is angularly displaced with respect to the outer ring. In this process, when the outer peripheral surface of the rotating shaft presses the inner surface of the first trough portion, the inclined surface portion is deformed in the standing direction with the protrusion that is in contact with the shoulder portion of the outer ring as a fulcrum. It is possible to effectively prevent the portion from being caught between the shoulder portion of the outer ring and the rotating shaft.

  Hereinafter, a preferred embodiment of a universal joint boot according to the present invention will be described with reference to the drawings. First, FIG. 1 is a sectional view showing a universal joint boot according to this embodiment in an unmounted state, FIG. 2 is a sectional view showing a state where the boot of FIG. 1 is mounted on the universal joint, and FIG. It is sectional drawing which shows the state which the boot received deformation | transformation by the angular displacement of a rotating shaft from the state of.

  The boot 1 of the present invention shown in FIG. 1 is formed of a rubber-like elastic material or a flexible synthetic resin material, and has a basic structure similar to that of the conventional one described above. The bellows portion 11 is formed at one end of the bellows portion 11, which has three crest portions 111, 112, 113 and three trough portions 114, 115, 116 extending in the circumferential direction. The large-diameter attaching portion 12 and the small-diameter attaching portion 13 formed at the other end of the bellows portion 11 are formed.

  On the outer peripheral surface of the large-diameter mounting portion 12, a band mounting groove 12a that is continuous in the circumferential direction for mounting the metal fastening band 3 shown in FIG. 2 is formed. A seal protrusion 12b continuous in the direction is formed. Similarly, on the outer peripheral surface of the small-diameter mounting portion 13, a band mounting groove 13a continuous in the circumferential direction for mounting the metal fastening band 4 is formed, and on the inner peripheral surface in the circumferential direction. A continuous seal protrusion 13b is formed.

  Reference numeral 2 in FIG. 2 denotes a PJT joint as a universal joint. The outer ring 21 is formed at the end of one rotating shaft (not shown) and a bearing mechanism (not shown) inside the outer ring 21. And the other rotating shaft 22 provided so as to be angularly displaceable with respect to the axis of 21. At a predetermined position on the outer peripheral surface of the rotating shaft 22 protruding from the outer ring 21, a circumferentially continuous fitting groove 22 a for fitting with the inner peripheral surface of the small-diameter mounting portion 13 in the boot 1 is formed.

  On the inner peripheral surface of the bellows portion 11 on the side of the large-diameter mounting portion 12, a protrusion 14 is formed continuously in the circumferential direction so as to be in contact with the end surface of the shoulder portion 21 a of the outer ring 21 of the PJT joint 2. From there, the slope portion 15 rising in a conical shape is formed so as to fall toward the inner peripheral side toward the valley portion (hereinafter referred to as the first valley portion) 114 on the side of the largest diameter attachment portion 12 in the bellows portion 11. ing. The rising angle β of the slope 15 is 60 to 70 °.

In addition, since the rising angle β of the slope portion 15 is made larger than before, the axial dimension of the slope portion 15 becomes larger than before. As a result, the axial height h ₁ of the protrusions 14 is the end face and the contact of the shoulder portion 21a of the outer ring 21 is relatively small. Therefore, in the conventional boot 100 shown in FIG. 4, the axial height h 1 of the annular protrusion 101h is 3 mm or more, whereas in this embodiment, the axial height h ₁ of the protrusion 14 is 1. It is about ~ 2mm.

  In the above-described configuration, as shown in FIG. 2, the boot 1 has a large-diameter attachment portion 12 fixed to the outer peripheral surface of the outer ring 21 of the PJT joint 2 by the fastening band 3 and a small-diameter attachment portion 13. However, the outer ring 21 and the rotary shaft 22 are allowed to be angularly displaced by being fastened and fixed to the outer peripheral surface of the rotary shaft 22 by the other fastening band 4 while being fitted to the fitting groove 22a. On the other hand, foreign matter can be prevented from entering the inside of the outer ring 21 and lubricating grease or the like filled in the outer ring 21 can be prevented from leaking to the outside. Further, in this mounted state, the protrusion 14 formed on the inner peripheral surface of the end portion of the bellows portion 11 on the large diameter attachment portion 12 side is in contact with the end surface of the shoulder portion 21 a of the outer ring 21.

  Since the boot 1 is rotated together with the outer ring 21 and the rotating shaft 22 of the PJT joint 2, the bellows portion 11 is stretched in a half cycle of rotation when the rotating shaft 22 is angularly displaced with respect to the axis of the outer ring 21. In other half-cycles, deformation such as contraction is repeated.

  As shown in FIG. 3, according to the boot 1 of the present invention, the rotating shaft 22 is slid out in a direction in which a roller mechanism (not shown) in the outer ring 21 of the PJT joint 2 is pulled out from the outer ring 21. Even if the angle is greatly displaced, the first trough 114 on the side of the largest diameter attachment portion 12 in the bellows portion 11 is not caught between the shoulder portion 21a of the outer ring 21 and the rotating shaft 22.

  This is because the rising angle β of the slope portion 15 formed on the inner periphery of the end portion of the bellows portion 11 on the large-diameter mounting portion 12 side is set to 60 ° or more, so that the rotation shaft 22 is angularly displaced with respect to the outer ring 21. When the one trough portion 114 is pressed in the radial direction, the slope portion 15 is deformed so as to stand up, so that the force for pushing the protrusion 14 riding on the shoulder portion 21a of the outer ring 21 outward in the radial direction is compared. Since the slope portion 15 is supported by the shoulder portion 21a of the outer ring 21 via the protrusion 14, the slope portion 15 does not fall down even if the rotary shaft 22 is further angularly displaced. This is because the projection 14 is displaced so as to rise up with the fulcrum 14 as a fulcrum.

  If the rising angle β of the slope 15 is less than 60 °, when the first valley 114 is pressed in the radial direction by the rotating shaft 22 that is angularly displaced with respect to the outer ring 21, the first valley 114 is Thus, the protrusion 14 is pushed radially outward from the top of the shoulder 21a of the outer ring 21, so that the above-described effects cannot be obtained. Further, when the rising angle β of the slope portion 15 is larger than 70 °, the height difference Δh between the first valley portion 114 and the mountain portion 111 adjacent thereto becomes too small, and the required height difference Δh is ensured. For this purpose, it is necessary to increase the diameter of the peak 111, and as a result, a predetermined expansion / contraction operation cannot be obtained. Therefore, the rising angle β of the slope portion 15 is defined as 60 to 70 °.

It is sectional drawing of the unmounted state which shows preferable embodiment of the boot concerning this invention. It is sectional drawing which shows the state with which the boot of FIG. 1 was mounted | worn to the universal joint. FIG. 3 is a cross-sectional view showing a state where the boot is deformed by the angular displacement of the rotation shaft from the state of FIG. 2. It is sectional drawing of the mounting state which shows the boot concerning a prior art. FIG. 5 is a cross-sectional view showing a state where the boot is deformed by the angular displacement of the rotation shaft from the state of FIG. 4.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boot 11 Bellows part 114 First trough part 12 Large diameter attachment part 13 Small diameter attachment part 14 Projection part 15 Slope part 2 PJT joint (universal joint)
21 Outer ring 22 Rotating shaft 3, 4 Tightening band

Claims (1)

  The bellows part (11), a large-diameter attachment part (12) formed at one end of the bellows part (11), and a small-diameter attachment part (13) formed at the other end of the bellows part (11), The large-diameter mounting portion (12) is fitted on the outer peripheral surface of the outer ring (21) of the universal joint (2), and the small-diameter mounting portion (13) is provided to be angularly displaceable with respect to the outer ring (21). A protrusion that is fitted to the outer peripheral surface of the rotating shaft (22) and contacts the shoulder (21a) of the outer ring (21) on the inner surface of the bellows portion (11) on the side of the largest diameter mounting portion (12). (14) is formed, and the slope portion (15) is directed toward the first trough portion (114) on the side of the largest-diameter mounting portion (12) among the trough portions of the bellows portion (11). ) From the inner peripheral side to the inner peripheral side, and the rising angle (β) of the inner surface of the slope portion (15) is 60 to 70 °. Universal joint boots.

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