JP2008025751A - Sealing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing structure for a constant velocity universal joint boot for exhibiting stable sealing performance over a long period while holding high sealing performance even in severe working environment under high temperature conditions. <P>SOLUTION: The sealing structure is provided for sealing between a shaft 9 connected to an inside joint member of a constant velocity universal joint and a constant velocity universal joint boot 1. On a shaft fixed portion 11 of the boot 1 to which a boot band 18 is fastened, an annular protruded portion 25 is provided to be pressed against the shaft 9. The annular protruded portion 25 has a protruded body 27 protruded from the inner diameter face of the shaft fixed portion 11 toward the inner diameter, and a small protrusion 26 protruded from the inner diameter end of the protruded body 27 toward the inner diameter so as to be crushed in close contact with the shaft. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a seal structure, and more particularly to a seal structure between a shaft connected to an inner joint member of a constant velocity universal joint and a boot for the constant velocity universal joint.

  Constant velocity universal joints used for power transmission in automobiles and various industrial machines are equipped with bellows-shaped boots to prevent foreign materials such as dust from entering the joints and leakage of grease enclosed in the joints. Is done.

  For example, as shown in FIGS. 4 and 5, this type of boot includes a large diameter portion 102 fixed to the outer ring 101 of the constant velocity universal joint 100, a small diameter portion 105 fixed to a shaft 104 extending from the inner ring 103, and a large diameter portion. It has a bellows part 108 provided between the diameter part 102 and the small diameter part 105 and having valleys 106 and peaks 107 alternately formed. And the large diameter part 102 and the small diameter part 105 are fixed by attaching the boot band 109, respectively.

  That is, band mounting grooves 110 and 111 are provided on the outer peripheral surface of the large-diameter portion 102 and the outer peripheral surface of the small-diameter portion 105, respectively, and the boot bands 109 and 109 are fitted into the grooves 110 and 111, respectively. The boot mounting portion of the shaft 104 is provided with a boot groove 112 and protrusions (circumferential protrusions) 113 and 113 on both sides of the boot groove 112. In this case, by tightening the boot band 109, the protrusions 113 and 113 are bitten into a part of the small diameter portion 105 of the boot, thereby improving the sealing performance.

  Further, as shown in FIG. 6, a plurality of circumferential grooves 115 are provided in the shaft 104, and by tightening the boot band 109, a part of the inner circumferential surface of the small diameter portion 105 is fitted into these circumferential grooves 115. Some of them are

Further, there is a type in which an annular ridge is provided on the inner peripheral surface of the small-diameter portion of the boot, and this annular ridge is fitted to the groove on the mounted side (Patent Document 1).
Japanese Utility Model Publication No. 61-129968

  By the way, in recent years, the use environment of the constant velocity universal joint for automobiles has become severe, such as space saving, layout close to the exhaust pipe, and high exhaust temperature. Therefore, the required performance is increasing for the constant velocity universal joint boot, and the resin boot is widely applied.

  However, the sealing performance of the tightening portion by the boot band is lowered due to a change with time. For this reason, even if the shaft is provided with protrusions as shown in FIGS. 4 and 5, or a plurality of circumferential grooves as shown in FIG. Even if the peripheral surface is provided with an annular ridge (described in Patent Document 1), the fastening effect is not sufficient. In recent years, resin boots made of thermoplastic elastomers have become widespread because they are more excellent in fatigue, wear and high-speed rotation (running performance during rotation) than rubber boots (CR boots). Such resin boots are greatly affected by heat, and when exposed to high temperatures, deterioration of the sealing performance is accelerated. This is because, under a high temperature atmosphere, the change in compression set of the thermoplastic elastomer is large, the repulsive force is reduced, and so-called “sagging” occurs. In particular, this tendency is remarkable in a high temperature environment (high temperature atmosphere) on the differential gear side (inboard side). For this reason, the conventional seal structure cannot exhibit a stable sealing function over a long period of time.

  In view of the above problems, the present invention is capable of maintaining a high sealing performance even in a severe use environment such as a high temperature condition, and capable of exhibiting a stable sealing performance over a long period of time. A seal structure for a universal joint boot is provided.

  The seal structure of the present invention is a shaft of a boot for tightening a boot band in a seal structure between a shaft connected to an inner joint member of a constant velocity universal joint and a boot for a constant velocity universal joint fitted on the shaft. The fixing portion is provided with at least one annular protrusion pressed against the shaft, and the annular protrusion protrudes in the inner diameter direction from the inner diameter surface of the shaft fixing portion, and the inner diameter end of the protrusion main body. It is composed of minute protrusions that protrude in the inner diameter direction and are crushed in a shaft-close state.

  Due to the tightening force obtained by fastening the boot band to the shaft fixing portion of the boot, the annular projection on the boot side can be brought into close contact with the shaft to enhance the sealing effect. Further, even if the repulsive force is reduced under a high temperature atmosphere, the minute protrusions are crushed so that the shaft contact portion can be easily followed and stably in close contact.

  The cross-sectional shape of the protrusion main body of the annular protrusion may be a trapezoidal shape that narrows from the outer diameter side toward the inner diameter side, or the cross-sectional shape of the minute protrusion may be a semicircular shape having an arc on the inner diameter side.

  A pair of circumferential projections can be provided on the boot mounting portion of the shaft, and the annular projection can be brought into pressure contact with the outer surface of the shaft between the pair of circumferential projections. Thereby, while a pair of circumferential direction protrusion part bites into the shaft fixing | fixed part of a boot, the cyclic | annular protrusion part by the side of a boot press-contacts to a shaft outer-diameter surface between circumferential direction protrusion parts.

  Since the boot material is made of thermoplastic elastomer, the constant velocity universal joint boot is excellent in fatigue, wear and high-speed rotation (running performance during rotation).

  According to the present invention, the annular protrusion on the boot side is pressed against the shaft, and the sealing performance can be improved. Further, in a high temperature atmosphere, the minute protrusions are crushed so that they can easily follow the shaft contact portion and stably adhere (closely). That is, it is possible to prevent the sealing performance from being lowered by the so-called “sagging” of the boot caused by the heat effect, and to have a stronger sealing performance.

  By making the cross-sectional shape of the protrusion main body of the annular protrusion into a trapezoidal shape that narrows from the outer diameter side toward the inner diameter side, the pressing force from the minute protrusions in the boot mounting state (boot band tightening state) is reduced. There is an advantage that it can be received stably and is excellent in strength. Further, by making the cross-sectional shape of the microprotrusions into a semicircular shape in which the inner diameter side is an arc, a stable pressure contact state can be secured at the boot mounting portion. In addition, since the contact area with the boot mounting portion can be made relatively small, the contact can be made with a high surface pressure, and the sealing performance can be further improved.

  The pair of circumferential projections can be bitten into the shaft fixing portion, and the annular projection on the boot side can be pressed against the outer diameter surface of the shaft between the circumferential projections. Thereby, the sealing effect can be further enhanced.

  Since the boot material is made of a thermoplastic elastomer, the constant velocity universal joint boot is excellent in fatigue, wear and high-speed rotation (running performance during rotation), and can exhibit a stable function as a boot. Moreover, even if such a thermoplastic elastomer that is greatly affected by heat is used, a stable sealing effect can be exhibited over a long period of time in a high-temperature atmosphere.

  Embodiments of the present invention will be described below with reference to FIGS.

  FIG. 1 shows a constant velocity universal joint 2 and a constant velocity universal joint boot 1 in which the seal structure of the present invention is used. This constant velocity universal joint 2 has a plurality of guide grooves (track grooves) 3 on its inner peripheral surface. An outer ring 4 as an outer joint member formed in the axial direction, an inner ring 6 as an inner joint member formed with a plurality of guide grooves (track grooves) 5 on the outer peripheral surface, a guide groove 3 of the outer ring 4 and a guide groove of the inner ring 6 5, a plurality of balls 7 arranged on a ball track formed in cooperation with 5, a cage 8 having a pocket 8 a for accommodating the balls 7, and the like. Further, the shaft 9 is coupled to the inner periphery of the inner ring 6 via torque transmission means such as serrations and splines.

  The constant velocity universal joint 2 is not limited as long as the constant velocity universal joint boot 1 can be attached to the constant velocity universal joint 2, so that even a fixed type constant velocity universal joint is a sliding type constant velocity universal joint. May be.

  The constant velocity universal joint boot 1 is made of, for example, a thermoplastic elastomer such as ester, olefin, urethane, amide, or styrene. Thermoplastic elastomers have intermediate properties between resin and rubber. Although the thermoplastic elastomer is an elastic body, it can be processed by a normal molding machine for thermoplastic resins.

  The constant velocity universal joint boot 1 is attached to the large diameter portion 10 attached to the open end of the outer joint member (outer ring 4) of the constant velocity universal joint 2 and the inner joint member (inner ring 6) of the constant velocity universal joint 2. A small-diameter portion 11 to be attached to the connected shaft 9, and a ridge portion 12 and a valley portion 13 that are provided between the large-diameter portion 10 and the small-diameter portion 11 and are alternately arranged along the axial direction. And a bellows portion 14. The mountain part 12 and the valley part 13 are connected by an inclined part 15.

  A boot mounting portion 16 made of a circumferential notch is provided on the outer peripheral surface on the opening side of the outer ring 4, and the large-diameter portion 10 is fitted on the boot mounting portion 16. Then, the large-diameter portion 10 is fixed to the outer ring 4 by fitting the boot band 18 into the fitting groove 17 formed on the outer peripheral surface of the large-diameter portion 10.

  The shaft 9 is provided with a boot mounting portion 22 having a boot mounting groove 20 along the circumferential direction at a position protruding from the outer ring 4 by a predetermined amount, and the small diameter portion 11 is externally fitted to the boot mounting portion 22. Circumferential protrusions (protrusions) 23 and 24 are provided at the opening end (axial end) of the boot mounting groove 20. The circumferential protrusions 23 and 24 have the same outer diameter and are set to be larger than the outer diameter of the boot mounting portion 22. Moreover, the width dimension (axial direction length) of the outer peripheral surfaces 23a and 24a of the circumferential direction projection parts 23 and 24 is set equally.

  As shown in FIG. 2, two annular protrusions 25 are formed on the inner peripheral surface of the small diameter portion (shaft fixing portion) 11 of the boot 1. That is, the annular protrusion 25 includes a protrusion body 27 that protrudes in the inner diameter direction from the inner diameter surface of the shaft fixing portion 11 and a minute protrusion 26 that protrudes in the inner diameter direction from the inner diameter end of the protrusion body 27. ing. The cross-sectional shape of the protrusion main body 27 is a trapezoidal shape that becomes thinner from the outer diameter side toward the inner diameter side. Moreover, the cross-sectional shape of the microprotrusion 26 is a semicircular shape having an arc on the inner diameter side.

  In this case, as shown in FIGS. 2 and 3, the projecting length A of each annular projecting portion 25 is set substantially equal to the depth B of the boot mounting groove 20, and the combined width dimension C thereof. The (shaft axial length) is set smaller than the width dimension E (shaft axial length) of the boot mounting groove 20.

  Further, flat bulging portions 28 and 28 may be provided at the corner portion between the main body portion 27 of the annular protrusion 25 and the inner diameter surface of the shaft fixing portion 11 of the boot.

  The small-diameter portion 11 is fixed to the shaft 9 by mounting the boot band 18 in the band mounting groove 29 in a state where the small-diameter portion 11 of the boot 1 is externally fitted to the boot mounting portion 22. In this case, as shown in FIG. 3, the circumferential protrusions 23 and 24 bite into the inner peripheral surface of the small-diameter portion 11 of the boot 1, and the annular protrusion 25 fitted in the boot mounting groove 20 includes the boot Press contact with the bottom surface of the mounting groove 20. Accordingly, the small diameter portion 11 of the boot 1 can be mounted (fixed) to the boot mounting portion 22.

  Thus, in the seal structure of the present invention, by tightening the boot band 18 to the shaft fixing portion 11 of the boot 1, the annular protrusion 25 on the boot side is pressed against the shaft 9 and the sealing performance can be improved. By the way, if the compression set is small, the restoring force is excellent. Therefore, in this state, the sealing property is excellent. However, as the compression permanent strain increases, the repulsive force (restoring force) decreases and the sealing property is inferior. For this reason, even if it is used in a high-temperature atmosphere and the repulsive force is reduced, the minute protrusions 26 are crushed, thereby making it easier to follow the shaft contact portion and improving the adhesion, thereby reducing the sealing performance. It is preventing. That is, the so-called “sagging” of the boot 1 caused by the heat effect does not cause a decrease in the sealing performance, and it is possible to have a stronger sealing performance. As described above, even when the constant velocity universal joint boot of the present invention is used in a high temperature atmosphere, a stable sealing function can be exhibited over a long period of time.

  The cross-sectional shape of the protrusion main body 27 of the annular protrusion 25 is a trapezoidal shape that becomes narrower from the outer diameter side toward the inner diameter side, so that the pressing force from the minute protrusion 26 in the boot mounting state (shaft pressure contact state) Can be stably received, and there is an advantage that it is excellent in strength. In addition, by making the cross-sectional shape of the minute protrusion 26 a semicircular shape having an arc on the inner diameter side, a stable pressure contact state can be secured on the boot mounting portion 22. Moreover, since the contact area with the boot mounting portion 22 can be made relatively small, the contact can be made with a high surface pressure, and the sealing performance can be further improved.

  A pair of circumferential projections 23, 24 are provided on the boot mounting portion 22 of the shaft 9, and the annular projection 25 is pressed against the outer surface of the shaft between the pair of circumferential projections 23, 24. That is, the pair of circumferential projections 23 and 24 bite into the shaft fixing portion 11 of the boot 1, and the annular projection 25 on the boot side is pressed against the shaft outer diameter surface between the circumferential projections 23 and 24. Thereby, the sealing effect can be further enhanced.

  In particular, since the boot material is made of a thermoplastic elastomer, the constant velocity universal joint boot 1 is excellent in fatigue, wear and high-speed rotation (running performance during rotation), and exhibits a more stable function as the boot 1. be able to. Moreover, even if such a thermoplastic elastomer that is greatly affected by heat is used, a stable sealing effect can be exhibited over a long period of time in a high-temperature atmosphere.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, the number of the annular protrusions 25 is not limited to two. 1 or 3 or more may be sufficient. In addition, when there are many microprotrusions 26, the more excellent sealing effect can be exhibited. Also, as the cross-sectional shape of the protrusion main body 27, various shapes such as a triangle and a rectangle can be selected. When a plurality of annular protrusions 25 are provided, all the annular protrusions 25 may have the same or different dimensions, and a plurality of annular protrusions arbitrarily selected from all the annular protrusions 25 may be used. Only the portion 25 may have the same size and shape. Further, the flat bulging portion 28 may not be provided.

  Further, the cross-sectional shape of the minute protrusions 26 is not limited to a semicircular shape, and may be a polygonal shape. That is, the size of the small protrusion 26 is such that it can be crushed in a state of being tightened by the boot band 18 at the temperature of the part where the seal structure is used, and the close contact (tightness) with the shaft 9 can be improved. Any shape is acceptable.

  In the embodiment, the boot mounting groove 20 is formed between the pair of circumferential protrusions 23 and 24. However, the boot mounting groove 20 may be omitted. Moreover, when providing the groove | channel 20 for boot attachment, various things, such as a semicircle shape, a triangular shape, trapezoid shape, a rectangular shape, are employable as the cross-sectional shape.

  The boot material is preferably a thermoplastic elastomer having excellent durability such as fatigue and wear, heat aging resistance, and oil resistance, but may be a rubber material such as chloroprene.

It is sectional drawing of the constant velocity universal joint which uses the seal structure which shows embodiment of this invention. It is a principal part expanded sectional view of the said boot for constant velocity universal joints. It is an expanded sectional view of the seal structure of the constant velocity universal joint. It is sectional drawing of the constant velocity universal joint using the conventional seal structure. It is an expanded sectional view of the seal structure of the conventional constant velocity universal joint. It is an expanded sectional view of the seal structure of another conventional constant velocity universal joint.

Explanation of symbols

1 boot for constant velocity universal joint 6 inner ring 9 shaft 11 small diameter portion 18 boot band 23 circumferential projection 24 circumferential projection 25 annular projection 26 minute projection 27 projection main body

Claims (5)

In the seal structure between the shaft connected to the inner joint member of the constant velocity universal joint and the boot for the constant velocity universal joint fitted on the shaft,
The shaft fixing portion of the boot for fastening the boot band is provided with at least one annular protrusion pressed against the shaft, and the annular protrusion protrudes in the inner diameter direction from the inner diameter surface of the shaft fixing portion, and the protrusion A seal structure characterized in that it is composed of minute protrusions that protrude in the inner diameter direction from the inner diameter end of the main body and are crushed in a shaft-tight state.   The seal structure according to claim 1, wherein a cross-sectional shape of the projecting portion main body of the annular projecting portion is a trapezoidal shape that narrows from the outer diameter side toward the inner diameter side.   The seal structure according to claim 1 or 2, wherein a cross-sectional shape of the minute protrusion of the annular protrusion is a semicircular shape having an arc on the inner diameter side.   4. A pair of circumferential projections are provided on the boot mounting portion of the shaft, and the annular projection is pressed against an outer diameter surface of the shaft between the pair of circumferential projections. Either seal structure.   The seal structure according to any one of claims 1 to 4, wherein a boot material of the constant velocity universal joint boot is made of a thermoplastic elastomer.

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