JPH083715Y2 - Flexible boots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a flexible boot for covering a joint of an automobile, an industrial machine, or the like that changes in angle.

<Prior Art> FIG. 5 shows a constant velocity joint used for an axle of an automobile as an example of a joint with a change in angle. The constant velocity joint 1 is provided between the inner ring 3 provided at one end of the first shaft 2, the outer ring 5 provided at the other end of the second shaft 4, and the inner ring 3 and the outer ring 5. And a ball 6 for transmitting rotation. The rubber flexible boot 7 is the first
The small-diameter mounting portion 8 fitted to the outer periphery of the shaft 2, the large-diameter mounting portion 9 fitted to the outer periphery of the outer ring 5, and the bellows portion 10 connecting the two. Internal space of flexible boot 7
11 is filled with grease, and the small-diameter mounting portion 8 and the large-diameter mounting portion 9 are fastened to the shaft 2 by tightening the fasteners 12 and 13, respectively.
And by fixing the outer ring 5 to the constant velocity joint 1
Covers in a sealed state.

Rotational force from the first shaft 2 is transmitted to the second shaft 4 via the ball 6, and even if the relative angle between the first shaft 2 and the second shaft 4 changes during that time, the first Since the distance between the center of the shaft 2 and the ball 6 and the distance between the center of the second shaft 4 and the ball 6 are equal, the rotational force can be transmitted at a constant speed without changing the angular velocity. When the relative angle between the shafts 2 and 4 changes, the bellows portion 10 of the flexible boot 7 expands on one side and contracts on the other side to correspond to the angle change, and holds the grease enclosed inside and waterproof and dustproof. Holds functions such as. The same applies when the rotational force is input from the second shaft 4.

In the case of the constant velocity joint 1 used for the axle of such an automobile, since it rotates at high speed and has a large repetitive displacement at a high operating angle, the flexible boot 7 covering it is also greatly deformed. For this reason, as the flexible boot 7, as shown in the figure, a boot having three peaks, which is most advantageous for expansion, contraction, wear and deformation due to centrifugal force, is generally used. Recently, along with the downsizing of engine rooms, downsizing of flexible boots has been required.

<Problems to be solved by the invention> However, if the flexible boot is downsized,
There is a problem that the bellows deployment length is insufficient and the expansion ratio increases and the durability decreases when a high operating angle is attached. Particularly, the third valley of the bellows portion is closest to the center of operation of the joint, and therefore has a larger deformation amount than the other valley portions.

Therefore, an object of this invention is to provide a flexible boot having a small size and high durability.

<Means for Solving the Problems> The flexible boot according to the present invention has a valley bottom of the second valley between the second mountain and the third mountain counted from the small-diameter mounting portion side of the bellows part of the three-valley three-valley structure. The taper shape has a larger diameter toward the large-diameter mounting portion side, and the taper angle is in the range of 20 ° to 60 °, and the distance between the center of the second mountain and the center of the third mountain is first. The feature is that the distance from the center of the mountain to the center of the third valley is set in the range of 30% to 55%.

<Operation> By forming the valley bottom of the second valley into a tapered shape with an appropriate length that widens toward the large-diameter mounting portion side, it is possible to increase the bellows development length and distribute the stress throughout the bellows. You can When the boot is compressed, the second trough moves toward the larger diameter side in the axial direction to reduce the deformation amount of the third trough, and further increases the working angle of the joint where the interference with the axis of the second trough starts. can do. Further, since the taper portion has high rigidity, it is excellent in high speed.

<Embodiment> FIGS. 1 and 2 show an embodiment of the present invention. The flexible boot 21 is attached to the constant velocity joint 1 of the axle of the automobile, like the flexible boot 7 shown in FIG. The flexible boot 21 is made of chloroprene rubber and has a small diameter mounting portion 22 fixed to the shaft 2 and a large diameter mounting portion fixed to the shaft 4.
23, and a bellows portion 24 that connects the small-diameter mounting portion 22 and the large-diameter mounting portion 23 and has a substantially uniform thickness. The bellows part 24 is provided with three peaks, namely, a first mountain 25, a first valley 26, a second mountain 27, a second valley 28, a third mountain 29, and a third valley 30, counting from the small-diameter mounting portion 22 side. ,
The valley bottom portion 31 of the second valley 28 between the second mountain 27 and the third mountain 29 is tapered with an angle θ that widens toward the large-diameter mounting portion 23 side. This angle θ is defined by one axis 2 of the constant velocity joint 1.
As shown in FIG. 2, when an operating angle is provided, the both ends of the valley bottom are not bent points on the compression side, and the slope to the valley bottom are smoothly curved.
The range of 20 ° to 60 ° is preferable so that even if the valley bottom 31 is deformed, it does not contact the shaft 2 as much as possible. Further, the center-to-center distance B from the second mountain 27 to the third mountain 29, which is almost equal to the length of the valley bottom 31, is 30 of the center-to-center distance A from the first mountain 25 to the third valley 30.
It is set in the range of% to 55%. The value of B is 30% of A
If it is smaller than this, the length of the tapered valley bottom 31 becomes short, and when the shaft 2 of the constant velocity joint 1 has an operating angle,
The second ridge 27 and the third ridge 29 come into contact with each other, and wear is likely to occur. In particular, when the second crest 27 falls toward the third crest 29 side during compression because the tapered valley bottom 31 is provided, the second crest 27 becomes the third crest 29.
It is easy to wear due to line contact with. On the contrary, if the value of B is larger than 55% of A, the total length of the flexible boot 21 is limited.
Comes into contact with the shoulder portion 23a of the large-diameter mounting portion 23, and the third crest 29 is easily worn.

Next, the operation of the above embodiment will be described. As shown in FIG. 2, when the shaft 2 is tilted with respect to the shaft 4 to form an operating angle, the flexible boot 21 is compressed on the upper side and expanded on the lower side in the drawing. On the upper side to be compressed, since the valley bottom 31 of the second valley 28 has a taper shape that spreads toward the large-diameter mounting portion 23 side, the second peak 27 and the third peak 29 do not interfere with each other, and the taper is reduced. Due to the high rigidity of the part, the second valley
Since the valley bottom portion 31 of 28 does not largely drop and moves toward the large diameter side in the axial direction, the working angle of the constant velocity joint 1 which starts to interfere with the shaft 2 can be increased and wear can be prevented. Moreover, since the valley bottom and the slopes at both ends thereof are curved and deformed smoothly as a whole, the stress can be dispersed and the durability can be improved. Further, also on the lower extension side, since the entire slopes of the tapered valley bottom 31 and the second peaks 27 and the third peaks 29 adjacent to the tapered valley bottom 31 are smoothly curved, the stress is dispersed and the extension strain is generated. Is prevented.

Next, a test example of this device will be described. Set the dimensions of each part based on Fig. 3 and the table below,
Four flexible boots made of chloroprene rubber of JIS 60Hs level were prepared. The A: B ratio of each flexible boot is 25% for No. 1, 47% for No. 2 and 60 for No. 3.
%, No. 4 is 62%. Each of these boots is attached to the constant velocity joint 1 shown in FIG. 2, and the operating angle is 20 degrees and the rotation speed is 60.
The test was conducted by measuring the time until the boot broke at an ambient temperature of 0 rpm and room temperature. As shown in FIG. 4, the results of the test show that the boot No. 2 having the A: B ratio within the range of 30% to 55% according to the present invention has a very good result, and the boot No. out of the range. The 1,3,4 boots were not so effective as compared with the conventional example.

<Effects of the Invention> As described above, the flexible boot according to the invention is
Since the bottom of the second valley has a tapered shape with an appropriate length, the stress generated in the second valley is dispersed to prevent the occurrence of distortion, and the interference between the second peak and the third peak and the second valley. Wear due to interference between the valley bottom and the shaft is prevented, and a flexible boot with high durability can be realized. Also, due to the tapered valley bottom that spreads toward the large diameter mounting part side,
The grease enclosed in the flexible boot flows toward the joint mounted on the large-diameter mounting portion side to improve the lubrication of the joint and reduce the amount of grease.

[Brief description of drawings]

FIG. 1 is a partial sectional view of a flexible boot showing an embodiment of the present invention, FIG. 2 is a sectional view of the flexible boot shown in FIG. 1 attached to a constant velocity joint of an axle of an automobile, and FIG. Fig. 4 is a diagram showing the dimensions of each part of the flexible boot in the test example of the present invention, Fig. 4 is a graph showing the test results, and Fig. 5 is a cross-sectional view of the conventional flexible boot attached to the constant velocity joint of the axle of the automobile. is there. 1 ... Constant velocity joint, 2, 4 ... Shaft, 7, 21 ... Flexible boot, 8, 22 ... Small diameter mounting part, 9, 23 ... Large diameter mounting part, 10, 24 ...
Bellows, 25 ... 1st mountain, 26 ... 1st valley, 27 ... 2nd mountain, 28 ... 2nd valley, 29 ... 3rd mountain, 30 ... 3rd valley, 31 ... Tapered valley bottom.

Claims (1)

[Scope of utility model registration request] 1. A small-diameter mounting of the bellows portion, comprising a bellows portion having three peaks and three valleys of substantially uniform thickness, small-diameter mounting portions and large-diameter mounting portions provided at both ends of the bellows portion. The bottom of the second valley between the second peak and the third peak, which is counted from the section side, has a taper shape with a large diameter toward the large-diameter mounting portion side, and the taper angle is 20 ° to 60 °. In addition to setting the range, the distance between the center of the second mountain and the center of the third mountain is set in the range of 30% to 55% of the distance from the center of the first mountain to the center of the third valley. Features flexible boots.