JPH0523857Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a boot that covers between the outer member opening of a constant velocity joint used mainly in the drive shaft of an automobile and the drive shaft. This relates to a boot with improved sealing performance at the part attached to the shaft side.

[Conventional technology]

Generally, fixed constant velocity joints and sliding constant velocity joints are used, for example, in front drive shafts of front-wheel drive vehicles and rear drive shafts of independent suspension vehicles. Various types of constant velocity joints are employed, such as a bar field joint, a tripod joint, and a rebro joint.

These constant velocity joints are equipped with a boot that covers between the outer member opening and the drive shaft in order to retain grease inside the joint and prevent dust, water, etc. from entering from the outside.

That is, as shown in FIG. 2, the boot 10 is
The large diameter end 11 is attached to an outer race 21 which is an outer member of a constant velocity joint (bar field joint) 20 by a tightening band 31,
The small diameter end 12 is attached to the drive shaft 40 by a tightening band 32. The boot 10 is made of an elastic material such as rubber in order to have elasticity to accommodate the expansion and contraction of the joint and changes in the joint angle, and has an elastic bellows 13 formed in the middle thereof. has been done. Also,
The inside of the boot 10 is filled with grease to lubricate the joint. In addition, 22 is an inner race constituting an inner member, 23 is a cage that is spherically fitted to the inner spherical surface of the outer race 21 and the outer spherical surface of the inner race 22, and 24 is fitted to the window hole 25 of the cage 23, and the outer race 21 race groove 26 of the inner race 22 and race groove 2 of the inner race 22
The torque transmitting balls 7 are shown rotatably fitted into the inner race 22, and the distal end 41 of the drive shaft 40 is spline-fitted into the spline hole formed at the center of the inner race 22, thereby integrally connected.

As shown in FIG. 3, the small-diameter end 12 of the boot 10 has a thick annular portion 14 connected to a thin bellows 13 on its inner peripheral surface.
The thick annular portion 14 is fitted into a boot attachment annular groove 42 formed on the outer peripheral surface of the drive shaft 40 and fixed using a tightening band 32. This tightening band 32 is usually a one-touch type tightening band (for example, Japanese Patent Publication No. 14702/1983) in order to ensure assemblability suitable for mass production.

In the boot mounting structure using the one-touch type tightening band 32, large variations in tightening force occur due to manufacturing errors of each component. Moreover, the tightening force is not evenly distributed around the entire circumference of the band, and a part of the band is pulled and lifted at the bent part of the band, and the tightening force is partially reduced, causing damage to the boot seal area. It is known that there is a problem where grease leaks out from a gap that occurs between the two. In addition, grease may leak from the boot seal portion due to large expansion and contraction of the constant velocity joint 20 and the provision of a joint angle, changes in internal pressure of the boot due to temperature changes, and centrifugal force acting on the grease during high-speed rotation.

For this reason, we have conventionally attempted to equalize the tightening force of the tightening band by changing the shape of the tightening band or by making the bottom surface of the annular groove for band attachment formed on the outer periphery of the thick annular portion at the end of the boot a concave surface. (for example, Japanese Utility Model Application No. 57-10552), or one with an O-ring added to the boot seal (for example, Japanese Utility Model Application No. 56
-72963 Publication), and those in which a thin part is provided in the vicinity of the thick annular part to reduce rigidity so that the deformation stress of the bellows does not reach the boot seal part (for example, Utility Model No. 55- 38010) etc. have been proposed.

In addition, an annular protrusion is formed that extends radially inward from the bellows formed in the middle part of the boot, so as to prevent the grease inside the boot from moving from the large diameter end (joint part) side to the small diameter end side. A version (for example, US Pat. No. 3,623,340) has also been proposed.

[Problem that the invention attempts to solve]

However, in the boots for constant velocity joints having the above-mentioned configuration, as shown in FIG. That is, there is nothing that blocks the boot seal portion 15 and the grease injection portion 16 from each other.
Therefore, even if the various measures mentioned above are taken, the grease injection part 16 may be damaged due to the factors mentioned above.
If the internal pressure of the boot 10 increases or a large centrifugal force acts on the boot 10 during high-speed rotation, the grease injection part 1
It is not possible to reliably prevent the grease No. 6 from entering the boot seal portion 15.

Therefore, if grease enters the boot seal portion 15, the boot 10 will easily slip on the drive shaft 40, causing the small diameter end 1 of the boot to slip.
There is a risk that the thick annular portion 14 of No. 2 may come off from the annular groove 42 for attaching the boot of the drive shaft.
Further, the boot 10 may rotate relative to the drive shaft 40, causing the thick annular portion 14 to wear. Further, due to the relative rotation of the boot 10, the boot 10 is twisted, and in some cases, the bellows 1 is attached with a large joint angle.
The folds of No. 3 may come into contact with each other and slide, causing wear.

Therefore, when the grease enters the boot seal portion 15, there is a problem in that the grease easily leaks out from the boot seal portion 15 due to an increase in the internal pressure of the grease injection portion 16.

Therefore, an object of the present invention is to prevent grease from leaking from the boot seal by improving the sealing performance of the boot seal.

[Means for solving problems]

Therefore, the present invention employs the following configuration as a means for solving the above-mentioned problems.

That is, the present invention provides, in the constant velocity joint boot described above, a lip that extends inward in the radial direction from a portion close to the small diameter end toward the large diameter end, and is always in close contact with the drive shaft. It is characterized by being integrally formed.

Specifically, using FIG. 1 as an example,
The constant velocity joint boot 10 has its large diameter end attached to the outer member of the constant velocity joint, and its small diameter end 12 attached to the drive shaft 40 by a tightening band 32. In the sealing structure of the constant velocity joint boot 10 made of an elastic material such as rubber and having a retractable bellows 13 in the middle thereof, the drive shaft 40 is provided with a sealing structure directed from the small diameter end side of the boot 10 to the large diameter end side. A lip 18 is formed on the outer circumferential surface of the inclined portion and extends radially inward from the small diameter end side toward the large diameter end side. The lip 18 is provided at the small diameter end 12, and a space extending in the circumferential direction is formed between the lip 18 and the small diameter end 12 on the inclined part.

[Effect]

According to the above-mentioned means, when the internal pressure inside the boot, that is, in the grease injection part 16 becomes high due to various factors, and centrifugal force due to rotation of the drive shaft 40 acts, the lip 18 is moved from the large diameter end to the small diameter end. A force is applied to move it in the direction of the outer diameter (hereinafter referred to as axially outward) and in the outer radial direction. At this time, the lip 18 moves in the direction of the outer diameter away from the drive shaft 40, but at the same time, due to the space formed between the lip 18 and the small diameter end, it also moves smoothly outward in the axial direction. do. Therefore, since the diameter of the drive shaft 40 increases in the axially outward direction, the lip 18 always comes into close contact with the outer peripheral surface of the inclined portion of the drive shaft 40. Therefore, the lip 18 is connected to the drive shaft 40.
It is possible to follow the target without separating from the target and increase the tightening force.

Furthermore, since the lip 18 is inclined from the small diameter end side to the large diameter end side and extends radially inward, a force perpendicular to the inclined surface of the lip 18 also acts, and this force drives the lip 18. It acts as a force to press against the shaft 40 and a force to move the lip 18 axially outward. Therefore, the force pressing against the drive shaft 40 cancels out the force acting in the radially outer direction as described above, thereby reducing the force that moves the lip in the radially outer direction. Further, the force for moving the lip 18 outward in the axial direction can be smoothly moved due to the existence of the space formed between the lip 18 and the small diameter end, thereby increasing the tightening force.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 shows the main parts of a constant velocity joint boot according to one embodiment of the present invention.

In the figure, 10 indicates a constant velocity joint boot, 12 indicates a small diameter end portion, and 13 indicates a telescopic bellows formed in the middle portion. boots 1
0 is the large diameter end 11 as shown in FIG.
is attached to the outer race 21 of the constant velocity joint 20 by a one-touch type tightening band 31. The boot 10 is made of an elastic material such as rubber, and has a thick annular portion 14 projecting toward the inner circumference at its small diameter end 12. On the other hand, the boot mounting portion of the drive shaft 40 is
Its outer diameter is set large, and a boot mounting annular groove 42 is formed in the large diameter portion.
Then, the thick annular portion 14 at the small diameter end portion is fitted into this annular groove 42 . Reference numeral 32 denotes a one-touch type tightening band that is attached to the annular band attachment groove 17 formed on the outer periphery of the small diameter end 12 and tightens the small diameter end 12 to the drive shaft 40.

Now, it extends radially inward from a portion close to the small-diameter end 12 toward the large-diameter end (right side in the figure), and is always in close contact with the conical outer circumferential surface 43 of the drive shaft 40. The lip 18 is integrally molded by injection molding or the like.

The inner diameter dimension of this lip 18 in its free state is the same as that of the drive shaft 4, which is the mating member that comes into contact with it.
It is set smaller than the outer diameter dimension of the conical outer peripheral surface 43 of 0. In addition, the rubber hardness, wall thickness, It is designed to have a predetermined rigidity by adjusting the inclination angle, etc.

In the boot for a constant velocity joint configured as described above, when the internal pressure inside the boot 10, that is, in the grease injection part 16 increases due to large expansion and contraction of the constant velocity joint, provision of a joint angle, temperature change, etc. Since the lip 18 extends radially inward from a portion close to the small diameter end 12 toward the large diameter end, when the internal pressure of the grease injection part 16 increases, the lip 18
A resultant force of a force acting in a direction perpendicular to the inclined surface and a force acting in the direction of the outer diameter acts on the slanted surface. The force directed outward of the boot perpendicular to the inclined surface acts to press the lip 18 against the drive shaft 40, and is canceled out by the force acting in the outer radial direction, so that the force that tries to expand the lip 18 in the outer radial direction becomes smaller.

Furthermore, depending on the size of the internal pressure of the lip 18,
Due to the above-mentioned resultant force, it follows and moves on the inclined surface of the drive shaft 40. At this time, the diameter of the drive shaft 40 increases from the large diameter end side to the small diameter end side. Therefore, the tightening force of the lip 18 against the drive shaft 40 increases.

As a result, the sealing performance of the boot seal portion 15 is greatly improved, and even if the internal pressure of the grease injection portion 16 increases, the lip 18 reliably prevents grease from entering the boot seal portion 15.

Therefore, the small-diameter end portion 12 of the boot does not slip out of the annular groove 42 for attaching the boot of the drive shaft, and relative rotation is avoided, so that the problem of wear at this portion can be solved. Therefore, leakage of grease from the boot seal portion 15 can be effectively prevented. Furthermore, it is also possible to improve the durability of the boot 10.

Furthermore, the above-mentioned effect is achieved by a slight change in shape such as integrally forming the lip 18 in the vicinity of the small-diameter end 12 of the boot. Since no deterioration occurs, this is extremely advantageous in practical terms.

Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-mentioned embodiments, but includes various embodiments within the scope of the claims for utility model registration. For example, the material of the lip may be different from that of other boots (such as rubber hardness), or the lip may be formed as separate parts in advance and the two may be combined by appropriate means. Furthermore, it is also possible to form the lip into a double lip shape.

[Effect of idea]

As described above, according to the present invention, the sealing performance of the boot seal portion can be significantly improved, and leakage of grease from the boot seal portion can be effectively prevented.

[Brief explanation of the drawing]

Fig. 1 is an enlarged vertical cross-sectional view of the main part showing the driveshaft mounting part in a boot for constant velocity joint according to one embodiment of the present invention, and Fig. 2 shows the mounting structure of a general boot for constant velocity joint. FIG. 3 is an enlarged longitudinal sectional view of a main part of a conventional constant velocity joint boot corresponding to FIG. 1. Explanation of symbols, 10... Boot for constant velocity joint, 11... Large diameter end, 12... Small diameter end, 13
... Bellows, 14 ... Thick-walled annular portion, 15 ... Boot seal part, 16 ... Grease injection part, 17 ...
Annular groove for band attachment, 18... lip, 20...
Constant velocity joint, 21... Outer race (outer member), 31, 32... Tightening band, 40... Drive shaft, 42... Annular groove for boot attachment, 4
3...Conical outer peripheral surface.

Claims (1)

[Claim for Utility Model Registration] An elastic material such as rubber whose large diameter end is attached to the outer member of the constant velocity joint and the small diameter end is attached to the drive shaft by a tightening band, and which has a telescopic bellows in the middle. In the sealing structure of a boot for a constant velocity joint made of a material, an inclined portion having a diameter continuously decreasing from a small diameter end side to a large diameter end side of the boot is formed on the drive shaft, and the inclined portion A lip that extends radially inward from the small-diameter end side toward the large-diameter end side is provided on the outer circumferential surface of the small-diameter end portion, and the lip and the small-diameter end portion are connected to each other on the inclined portion. A seal structure for a boot for a constant velocity joint, characterized by a space extending in the circumferential direction between the two.