JP4657897B2 - Seal structure - Google Patents

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 sealed inside the joints. Is done.

For example, as shown in FIG. 8, 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 102. And the small-diameter portion 105, and a bellows portion 108 in which valleys 106 and peaks 107 are 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. Further, as shown in FIG. 8, the boot mounting portion of the shaft 104 includes a boot groove 112 and protrusions (circumferential protrusions) 113 and 113 on both sides of the boot groove 112. (Patent Document 1). 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. 9, 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
JP 2002-39383 A

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 projection is provided on the shaft as shown in FIG. 8 or a plurality of circumferential grooves are provided as shown in FIG. 9, the tightening 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). When such a resin boot is exposed to a high temperature, the deterioration of the sealing performance is accelerated. This is because the compression set of the thermoplastic elastomer is large and the repulsive force decreases, and this tendency is particularly remarkable in a high temperature environment (high temperature atmosphere) on the differential gear side (inboard side). For this reason, the conventional sealing structure cannot exhibit a stable sealing function over a long period of time.

  In view of the above problems, the present invention is for a constant velocity universal joint that can suppress a decrease in sealing performance even when used in a high temperature environment and can exhibit a stable sealing function over a long period of time. A boot seal structure is provided.

The seal structure of the present invention is a 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.
The boot mounting portion of the shaft, provided with a plurality of circumferential projections biting into the shaft fixing portion boots worn tightening the boot band to the shaft fixing portion of the boot fits within the axial width of the boot band, the boot In the mounted state, the amount of boot compression set by at least one circumferential projection is different from the amount of boot compression set by other circumferential projections.

  By making a difference in the amount of permanent compression set of the boot, the “sagging” of the sealing portion (small diameter portion) can be eased and the deterioration of the sealing performance can be suppressed.

Two or more circumferential projections having the same outer diameter are provided, and a circumferential projection having a smaller diameter than the circumferential projection is disposed between the circumferential projections having the same outer diameter. Thus, there is a difference in the amount of boot compression set between the circumferential projections having the same outer diameter and the circumferential projections having a smaller diameter, or between the circumferential projections having the same outer diameter. A circumferential protrusion having a larger diameter than that of the protrusion may be disposed to make a difference in the amount of permanent compression set between the circumferential protrusion having the same outer diameter and the large protrusion having a large diameter. Can do. Further, two or more circumferential protrusions having different outer diameter dimensions can be provided, and the boot compression set can be differentiated by the circumferential protrusions having different outer diameter dimensions.

That is, when a circumferential projection having a smaller diameter than these circumferential projections is disposed between circumferential projections having the same outer diameter, the compressive stress received by the circumferential projection having a smaller diameter is reduced on both sides. It becomes lower than the compressive stress which a direction protrusion part receives. For this reason, in the protrusion part adjacent to an axial direction, the compressive stress of the site | part which contacts differs, the "sag" of a seal part is relieve | moderated, and the fall of a sealing performance can be suppressed.

In addition, when a circumferential projection having a larger diameter than these circumferential projections is disposed between circumferential projections having the same outer diameter, the compressive stress received by the circumferential projection having a large diameter is It becomes higher than the compressive stress received by the circumferential protrusions on both sides. For this reason, as in the case described above, in the protruding portions adjacent to each other in the axial direction, the compressive stress of the contacting portion is different, the sag of the seal portion is alleviated, and the deterioration of the sealing performance can be suppressed.

  When two or more circumferential protrusions with different outer diameters are provided, the compressive stress applied to each of the different circumferential protrusions is different, and the “sagging” of the seal portion is alleviated and the deterioration of the sealing performance is suppressed. it can.

  Thus, by providing the circumferential protrusions having different outer diameter dimensions, it is possible to easily add a difference to the boot compression set.

  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).

  In the present invention, by making a difference in the amount of permanent compression set of the boot, the “sag” of the seal portion (small diameter portion) can be alleviated and deterioration of the sealing performance can be suppressed. Thus, 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.

By providing the circumferential protrusions having different outer diameter dimensions, a difference in the amount of permanent compression set of the boot can be easily applied, and the reliability in improving the sealing performance can be enhanced.

Because the boot material is made of thermoplastic elastomer, the boots for constant velocity universal joints are excellent in fatigue, wear, and high-speed rotation (running performance during rotation) and can exhibit more stable functions as boots. .

  Hereinafter, embodiments of the present invention will be described 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 according to the first embodiment of the present invention is used. The constant velocity universal joint 2 has a plurality of guide grooves ( An outer ring 4 as an outer joint member in which a track groove) 3 is formed in the axial direction, an inner ring 6 as an inner joint member in which a plurality of guide grooves (track grooves) 5 are formed on the outer peripheral surface, and a guide groove 3 in the outer ring 4 It comprises a plurality of balls 7 arranged on a ball track formed in cooperation with the guide groove 5 of the inner ring 6, 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 portion 12 and the valley portion 13 are connected by an inclined portion 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.

  As shown in FIGS. 1 to 3, the shaft 9 is provided with a boot mounting portion 22 having a boot mounting groove 20 along the circumferential direction at a position projecting from the outer ring 4 by a predetermined amount. The fitting portion 22 is externally fitted. Circumferential protrusions (protrusions) 23 and 24 are provided at the opening end (axial end) of the boot mounting groove 20. The circumferential protrusions (protrusions) 23 and 24 have outer diameters D1 and D2 larger than the outer diameter D of the boot mounting portion 22, and the outer diameters D1 and D2 are the same.

  Further, in the boot mounting groove 20, a circumferential projection (projection) 25 having a smaller diameter than the circumferential projections 23 and 24 is provided in the axial middle portion thereof. The outer diameter dimension D <b> 3 of the circumferential protrusion 25 is set smaller than the outer diameter dimension D of the boot mounting portion 22. Then, by providing the circumferential protrusion 25, the boot mounting groove 20 is formed between the circumferential protrusion 23 and the circumferential protrusion 25, the anti-bellows side groove 20 a, and the circumferential protrusion 25. And a bellows portion side groove portion 20b formed between the circumferential projection 24 and the circumferential projection 24. The width dimensions (axial lengths) W1 and W2 of the outer peripheral surfaces 23a and 24a of the circumferential projections 23 and 24 are set to be the same, and the width dimension (axial length) of the outer circumferential surface 25a of the circumferential projection 25 is set. ) It is set larger than W3.

  On the inner peripheral surface of the small-diameter portion 11 of the boot 1, as shown in FIG. 4, an annular protrusion 26 having a flat semi-elliptical cross section is provided corresponding to the boot mounting groove 20. A band mounting groove 27 is provided on the outer peripheral surface of the small diameter portion 11 of the boot 1.

Then, the small-diameter portion 11 of the boot 1 is fixed to the shaft 9 by fitting the boot band 18 to the band mounting groove 27 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. 2, 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 26 is fitted into the boot mounting groove 20, The protrusion 25 bites into the annular protrusion 26. Accordingly, the small diameter portion 11 of the boot 1 can be mounted (fixed) to the boot mounting portion 22.

At this time, since the circumferential projections 25 having a smaller diameter than the circumferential projections 23 and 24 are disposed between the circumferential projections 23 and 24 having the same outer diameter D1 and D2, the small-diameter projections 23 and 24 have a small diameter. The compressive stress received by the circumferential projection 25 is lower than the compressive stress received by the circumferential projections 23 and 24 on both sides. For this reason, in the projection parts 23 and 25 (25, 24) adjacent to an axial direction, the compressive stress of the site | part to contact differs.

As described above, in the seal structure of the first embodiment, one piece is provided in a state where the boot band 18 is fastened to the small diameter portion (shaft fixing portion) 11 of the boot 1 and the shaft fixing portion is attached to the shaft 9 (boot attachment state). The amount of boot compression set by the circumferential protrusions 25 differs from the amount of boot compression set by the other circumferential protrusions 23, 24. For this reason, the “sag” of the seal portion (small diameter portion) can be alleviated to suppress a decrease in the sealing performance, and the constant velocity universal joint boot 1 can be stably sealed even when used in a high temperature atmosphere. The function can be demonstrated for a long time.

  In particular, because the boot material is made of thermoplastic elastomer, the boots for constant velocity universal joints are excellent in fatigue, wear and high-speed rotation (running performance during rotation), and can exhibit more stable functions as boots. it can.

Next, FIG. 5 shows a second embodiment. In this case, the boot mounting groove 20 has an outer diameter dimension D4 in the axial middle portion thereof than the outer diameter dimensions D1, D2 of the circumferential protrusions 23, 24. A large-diameter circumferential protrusion (protrusion) 28 having a large diameter is also provided. The boot mounting groove 20 is formed between the anti-bellows portion side groove 20 a formed between the circumferential protrusion 23 and the circumferential protrusion 28, and between the circumferential protrusion 28 and the circumferential protrusion 24. It is divided into the bellows part side groove part 20b. The width dimensions (axial length) W1 and W2 of the outer circumferential surfaces 23a and 24a of the circumferential protrusions 23 and 24 are larger than the width dimension (axial length) W4 of the outer circumferential surface 28a of the circumferential projection 28. Is set.

Then, the small-diameter portion 11 of the boot 1 is fixed to the shaft 9 by fitting the boot band 18 to the band mounting groove 27 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. 6, 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 26 fits into the boot mounting groove 20, The protrusion 28 bites into the annular protrusion 26. Accordingly, the small diameter portion 11 of the boot 1 can be mounted (fixed) to the boot mounting portion 22.

At this time, since the circumferential projections 28 having a larger diameter than the circumferential projections 23 and 24 are arranged between the circumferential projections 23 and 24 having the same outer diameter D1 and D2, the large-diameter projections 23 and 24 are large. The compressive stress received by the circumferential projection 28 of the diameter is higher than the compressive stress received by the circumferential projections 23 and 24 on both sides. For this reason, in the projection parts 23 and 28 (28, 24) adjacent to an axial direction, the compressive stress of the site | part which contacts differs.

Thus, the seal structure of the second embodiment also has the same effects as the constant velocity universal joint boot of the first embodiment.

Next, FIG. 7 shows a third embodiment. In this case, in the shaft 9 shown in FIG. 5, the outer diameter dimension D2 of the circumferential protrusion 24 on the bellows portion side is set to the circumferential protrusion 23 on the anti-bellow portion side. Is set larger than the outer diameter D1. For this reason, the outer diameter dimensions of the circumferential protrusions 23, 28 and 25 are different, and D <D1 <D4 <D2.

In this case, the small-diameter portion 11 is fixed to the shaft 9 by fitting the boot band 18 in the band mounting groove 27 in a state where the small-diameter portion 11 of the boot 1 is externally fitted to the boot mounting portion 22. Become. Therefore, the circumferential protrusions 23 and 24 bite into the inner peripheral surface of the small diameter part 11 of the boot 1, and the circumferential protrusion 28 bites into the annular protrusion 26. Accordingly, the small diameter portion 11 of the boot 1 can be mounted (fixed) to the boot mounting portion 22.

In 3rd Embodiment, a difference arises in the amount of boot compression permanent distortion by each circumferential direction protrusion part 23,28,24. For this reason, the seal structure of the third embodiment also has the same effects as the constant velocity universal joint boot of the first embodiment.

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 circumferential protrusions of the shaft 9 is not limited to three. It may be four or more. In this case, even if the outer diameters are all different, at least two circumferential protrusions can have the same outer diameter. . Further, a circumferential projection having a larger diameter and a circumferential projection having a smaller diameter than the same circumferential projection may be arranged on the circumferential projection having the same outer diameter. A large-diameter circumferential protrusion can be disposed on the bellows side, and a small-diameter circumferential protrusion can be disposed on the bellows side.

Further, in each of the above embodiments, the small-diameter circumferential protrusion 25 and the large-diameter circumferential protrusion 28 are arranged in the axial center of the boot mounting groove 20. It may be shifted to the 23, 24 side. Further, in the case where the outer diameters of the circumferential protrusions are different from each other, in FIG. 7, the circumferential protrusion 23 on the side opposite to the bellows is made smaller and the circumferential protrusion 24 on the bellows is made larger. Alternatively, the circumferential protrusion on the side of the bellows part may have a large diameter, and the circumferential protrusion on the side of the bellows part may have a small diameter.

The width dimensions W1, W2, W3, and W4 of the circumferential protrusions 23, 24, 25, and 28 can be variously changed. For example, even if the width dimension W1 of the circumferential projection 23 is different from the width dimension W2 of the circumferential projection 24, the width dimensions W3 and W4 of the circumferential projections 25 and 28 are set to be different from those of the circumferential projections 23 and 24. You may make it larger than the width dimensions W1 and W1.

In the embodiment, the annular protrusion 26 is provided corresponding to the boot mounting groove 20, but such an annular protrusion 26 may not be provided. Further, as the cross-sectional shape of the annular protrusion 26, various shapes such as a semicircular shape, a triangular shape, a trapezoidal shape, and a rectangular shape can be adopted other than the flat semi-elliptical 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 explanatory drawing of the constant velocity universal joint using the seal structure which shows 1st Embodiment of this invention, and the boot for constant velocity universal joints. It is a principal part expanded sectional view of the said 1st Embodiment. It is a principal part enlarged view of the shaft used for the said 1st Embodiment. It is a principal part expanded sectional view of the boot for constant velocity universal joints used for the said 1st Embodiment. It is a principal part enlarged view of the shaft used for 2nd Embodiment of this invention. It is a principal part expanded sectional view of the said 2nd Embodiment. It is a principal part enlarged view of the shaft used for 3rd Embodiment of this invention. It is explanatory drawing of the constant velocity universal joint and boot for constant velocity universal joints using the conventional seal structure. It is explanatory drawing of the constant velocity universal joint which uses the other conventional seal structure, and the boot for constant velocity universal joints.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Constant velocity universal joint boot 2 Constant velocity universal joint 3 Guide groove 4 Outer ring 5 Guide groove 6 Inner ring 7 Ball 8 Cage 8a Pocket 9 Shaft 10 Large diameter part 11 Small diameter part 12 Mountain part 13 Valley part 14 Bellows part 15 Inclined part 16 22 Boot mounting portion 17 Fitting groove 18 Boot band 20 Boot mounting grooves 23, 24, 25, 28 Circumferential protrusions 23a, 24a, 25a, 28a Outer peripheral surface 26 Annular projection 27 Band mounting groove 28 Circumferential direction Protrusion 100 Constant velocity universal joint 101 Outer ring 102 Large diameter part 103 Inner ring 104 Shaft 105 Small diameter part 106 Valley 107 Mountain 108 Bellows part 109 Boot band 110 Band mounting groove 110 Each groove 112 Boot groove 113 Protrusion

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,
The boot mounting portion of the shaft, provided with a plurality of circumferential projections biting into the shaft fixing portion boots worn tightening the boot band to the shaft fixing portion of the boot fits within the axial width of the boot band, the boot A seal structure characterized in that, in the mounted state, the amount of boot compression set by at least one circumferential protrusion is different from the amount of boot compression set by another circumferential protrusion. Two or more circumferential projections having the same outer diameter are provided, and a circumferential projection having a smaller diameter than the circumferential projection is disposed between the circumferential projections having the same outer diameter. 2. The seal structure according to claim 1, wherein a difference in boot compression set is made between a circumferential projection having the same outer diameter and a circumferential projection having a small diameter. Two or more circumferential projections having the same outer diameter are provided, and circumferential projections having a larger diameter than these circumferential projections are disposed between the circumferential projections having the same outer diameter. The seal structure according to claim 1, wherein a difference in boot compression set is made different between a circumferential protrusion having the same outer diameter and a circumferential protrusion having a large diameter. 2. The seal structure according to claim 1, wherein two or more circumferential protrusions having different outer diameter dimensions are provided, and a difference in boot compression set is made between the circumferential protrusions having different outer diameter dimensions.   The seal structure according to claim 1, wherein a boot material of the constant velocity universal joint boot is made of a thermoplastic elastomer.

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