JP2010101377A - Constant velocity universal joint boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resin constant velocity universal joint boot capable of suppressing degradation of durability even when used at high-speed rotation. <P>SOLUTION: In the axial cross section of the resin constant velocity universal joint boot 1, a region on the radial inward side of a line A including the line A between the peak point of a mountain part 10 adjacent to a small diameter part 3 and the peak point of the mountain part 10 adjacent to a large diameter part 2 includes all of the mountain parts 10 held between both mountain parts 10. A magnitude relation among radial thicknesses T1-T5 of bent portions 11a located at valley parts 11 on a bellows part 4 is T1>T2>T3>T4>T5. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin boot attached to, for example, a constant velocity universal joint for a propeller shaft of an automobile.

  As is well known, for example, a constant velocity universal joint incorporated in a power transmission mechanism of an automobile is equipped with a boot for the purpose of preventing foreign matter such as dust from entering the joint and preventing leakage of grease enclosed in the joint. The

  The constant velocity universal joint has an outer joint member and a shaft extending from an inner joint member disposed inside the outer joint member. The boot attached to the constant velocity universal joint has a cylindrical shape, and has a large diameter portion, a small diameter portion, and a bellows portion as main components. The large diameter portion is attached to the outer joint member of the constant velocity universal joint. The small diameter portion is attached to a shaft extending from the inner joint member of the constant velocity universal joint. The bellows portion is interposed between the small-diameter portion and the large-diameter portion, and alternately has a mountain-shaped peak and a valley-shaped valley with respect to the outer side in the radial direction. This boot is usually attached to a constant velocity universal joint with the bellows portion compressed.

Chloroprene rubber (CR) has been mainly used as a material for the constant velocity joint boot, but in recent years, a thermoplastic resin material has been used to improve durability (see Patent Document 1).
Japanese Utility Model Publication No. 7-38758

  By the way, conventionally, a constant velocity universal joint has been often used for a drive shaft as an application for an automobile. For this reason, resin boots for constant velocity joints have also been developed for automobile drive shafts and are required to be able to bend to a large angle (50 °). And in order to satisfy | fill this request | requirement, the diameter of a boot increased, and in connection with this, the boot expanded by the centrifugal force at the rotational speed of about 3000 rpm, and there existed a case where durability had a problem.

  On the other hand, in recent years, constant velocity universal joints are often used for propeller shafts that transmit power to the rear wheels in order to improve fuel efficiency and NVH for automotive applications. For resin boots applied to constant velocity universal joints for automobile propeller shafts, a low angle (about 20 ° or less) is sufficient for bending, but it can be used even at high speeds of about 7000-10000 rpm. Required to be possible. For this reason, in a resin boot designed for a constant velocity universal joint used for a drive shaft, the boot may expand due to centrifugal force during high-speed rotation, which may reduce durability. This is a problem common not only to resin boots for constant velocity universal joints used for propeller shafts of automobiles but also to resin boots for constant velocity universal joints used at high speed rotation.

  Therefore, in view of the above circumstances, an object of the present invention is to provide a resin-made constant velocity universal joint boot capable of suppressing a decrease in durability even when used at high speed rotation.

  In order to solve the above-mentioned problem, the invention of claim 1 is a boot attached to a constant velocity universal joint having an outer joint member and a shaft extending from an inner joint member disposed inside the outer joint member. A large-diameter portion that is attached to the outer joint member, a small-diameter portion that is attached to the shaft, and a ridge portion that is interposed between the small-diameter portion and the large-diameter portion and has a mountain shape radially outward. In a boot for a constant velocity universal joint made of resin, which has a bellows portion alternately having a valley shape and is attached to the constant velocity universal joint in a state where the bellows portion is compressed, a small diameter portion in an axial cross section Each of the ridges sandwiched between the ridges in a region radially inward of the straight line including a straight line connecting the vertices of the ridges adjacent to the ridges and the ridges adjacent to the large diameter portion. And a large diameter portion in the bellows portion. At least one of the radial thickness of the bent portion located in the valleys, characterized by being thinner than the thickness of the bent portion is located at least one valley of the small diameter portion side of the.

  Here, the peak of the peak portion is strictly a point in contact with the straight line, and is not necessarily a point that becomes the maximum outer diameter of the peak portion (hereinafter the same).

  Here, the boundary between the “close to the large diameter portion” and the “close to the small diameter portion” in the bellows portion may be the axial center of the bellows portion, but at least in each of the “close to the large diameter portion” and the “close to the small diameter portion”. As long as one trough part is included, it may be other than the axial center of the bellows part (hereinafter the same).

  In the invention of claim 1, in the axially inner region including the straight line connecting the apex of the peak adjacent to the small diameter part and the apex of the peak adjacent to the large diameter part in the axial cross section, Each of the mountain parts sandwiched between both mountain parts is included. Thereby, as for the peak part pinched | interposed into the said two peak parts, centrifugal force is suppressed, As a result, expansion of this peak part can be suppressed. Moreover, since both the mountain parts are adjacent to the large diameter part attached to the outer joint member and the small diameter part attached to the shaft, expansion can be suppressed.

  In the invention of claim 1, the radial thickness of the bent portion located in at least one valley portion near the large diameter portion in the bellows portion is set to the thickness of the bent portion positioned in at least one valley portion near the small diameter portion. It was thinner. With this configuration, when the boot is attached to the constant velocity universal joint with the bellows portion compressed, the angle of at least one valley portion near the large diameter portion is larger than the angle of at least one valley portion near the small diameter portion. Narrow. When the angle of the valley is narrow, the adjacent peak is prevented from expanding. That is, it can suppress that the peak part near a large diameter part expand | swells from the peak part near a small diameter part. The peak near the large-diameter part is generally larger in diameter than the peak near the small-diameter part, and is easily expanded due to centrifugal force. Therefore, it is effective to suppress the expansion of the boot to suppress the expansion of the peak portion near the large diameter portion. In other words, the above configuration can effectively suppress the expansion of the boot.

  According to a second aspect of the present invention, in the first aspect of the invention, the thicknesses of the bent portions located in all the valley portions near the large-diameter portion in the bellows portion are set to bends located in all the valley portions near the small-diameter portion. It is made thinner than the said thickness of a part.

  According to the invention of claim 2, the effect of suppressing the expansion of the peak portion near the large diameter portion is suppressed more significantly than the peak portion near the small diameter portion. That is, the expansion of the boot can be suppressed more effectively.

  The invention of claim 3 is the invention of claim 2, wherein the thickness of the bent portion located in the valley portion near the large diameter portion in the bellows portion is gradually reduced as it shifts to the large diameter portion side. is there.

  According to the invention of claim 3, the effect of suppressing the expansion of the peak portion on the large diameter portion side among the peak portions near the large diameter portion is obtained. Among the ridges near the large-diameter portion, the ridge portion on the large-diameter portion side is large and easily receives centrifugal force, so that it easily expands. That is, the expansion of the boot can be effectively suppressed.

  According to a fourth aspect of the present invention, in the third aspect of the invention, the thickness of the bent portion located in the valley portion near the small diameter portion in the bellows portion is gradually reduced as it moves to the large diameter portion side. .

  According to the invention of claim 4, the effect of suppressing the expansion of the peak portion on the large diameter side in the peak portion near the small diameter portion is obtained. Among the ridges near the small-diameter portion, the ridge portion on the large-diameter portion side is generally large in diameter and easily receives a centrifugal force, so that it easily expands. That is, the expansion of the boot can be effectively suppressed.

  The invention of claim 5 is the invention of claim 3 or 4, wherein the largest diameter portion side of the bellows portion is a trough portion.

  According to the invention of claim 5, both sides in the axial direction are valleys in the peak part adjacent to the large diameter part. When the largest diameter part side of the bellows part is a peak part, only one axial side of the peak part adjacent to the large diameter part is a valley part. Therefore, the effect of suppressing the expansion of the peak portion adjacent to the large diameter portion by thinning the valley portion can be made larger than when the largest diameter portion side of the bellows portion is the peak portion. Usually, the peak part adjacent to the large diameter part has the largest outer diameter in the peak part, so that the effect of suppressing the expansion of the boot can be greatly increased.

  The invention of claim 6 is the invention according to any one of claims 1 to 5, wherein the bellows part has two or three valleys near the small diameter part.

  According to the sixth aspect of the present invention, in the boot for a constant velocity universal joint made of a resin having two or three valley portions near the small diameter portion in the bellows portion, the same effect as described above can be obtained.

  A seventh aspect of the present invention is the invention according to any one of the first to sixth aspects, wherein the number of the peak portions of the bellows portion is five or six.

  According to the invention of claim 7, the same effect as described above can be obtained in the resin constant velocity universal joint boot in which the number of the crest portions of the bellows portion is five or six.

  The invention of claim 8 is the invention according to any one of claims 1 to 7, wherein the constant velocity universal joint is used for a propeller shaft of an automobile.

  According to the eighth aspect of the invention, the same effect as described above can be obtained for the resin boot for a constant velocity universal joint used for the propeller shaft.

  A ninth aspect of the invention is a constant velocity universal joint to which the constant velocity universal joint boot according to any one of the first to eighth aspects is attached.

  According to invention of Claim 9, the effect similar to the above is obtained about the boots for resin constant velocity universal joints attached to the constant velocity universal joint.

  ADVANTAGE OF THE INVENTION According to this invention, even if it uses by high speed rotation, the boots for resin constant velocity universal joints which can suppress a durable fall can be provided.

  Hereinafter, the best mode for carrying out the present invention will be described.

  FIG. 1 shows a state in which a constant velocity universal joint boot according to an embodiment of the present invention is attached to a constant velocity universal joint. The boot 1 includes a large diameter portion 2, a small diameter portion 3, and a bellows portion 4 as main components. The constant velocity universal joint 5 includes an outer joint member 6, an inner joint member (not shown), a shaft 7 extending from the inner joint member, a torque that is interposed between the outer joint member 6 and the inner joint member, and transmits torque. A transmission member (not shown) is a main component.

  In FIG. 1, the constant velocity universal joint 5 is in a state where the operating angle is 0 °. In the present embodiment, the constant velocity universal joint 5 is for a propeller shaft of an automobile. The boot 1 is attached to the constant velocity universal joint 5 in a state of being slightly compressed in the axial direction.

  The type of the constant velocity universal joint 5 is not particularly limited. For example, a fixed type constant velocity universal joint such as a Rzeppa type, a barfield type, an undercut free type, a double offset type, a tripod type, a cross groove type, etc. The sliding type constant velocity universal joint can be applied. However, in the case of a sliding type constant velocity universal joint, the attached boot 1 is compressed in the axial direction in a state where the operating angle is 0 ° and the shaft 7 is farthest away from the outer joint member 6 in the axial direction. It is the state that was done.

  Although the material of the boot 1 will not be specifically limited if it is resin, For example, it is a thermoplastic polyester-type elastomer.

  The large-diameter portion 2 of the boot 1 is fitted at a predetermined position on the opening end side of the outer joint member 6 of the constant velocity universal joint 5 and is fastened and fixed by the boot band 8. The small diameter portion 3 of the boot 1 is fitted at a predetermined position on the shaft 7 of the constant velocity universal joint 5 and is fastened and fixed by a boot band 9.

  The bellows portion 4 is interposed between the large-diameter portion 2 and the small-diameter portion 3, and alternately has mountain-like peaks 10 and valley-like valleys 11 with respect to the radially outer side. Although the peak part 10 may be sufficient as the largest diameter part 2 side of the bellows part 4, it is the trough part 11 in this embodiment. The smallest diameter portion side of the bellows portion 4 is a peak portion 10. In the present embodiment, the number of ridges 10 is five, but may be six, and may be any of two to four, or seven or more.

  FIG. 2 shows an axial cross section of the boot 1 in a state where it is not attached to the constant velocity universal joint, that is, in a state where no external force is applied (natural state).

  A straight line A indicated by a dotted line in FIG. 2 connects an apex on the outer peripheral side of the peak portion 10 adjacent to the small diameter portion 3 and an apex on the outer peripheral side of the peak portion 10 adjacent to the large diameter portion 2. Each of the three peak portions 10 sandwiched between the peak portion 10 adjacent to the small diameter portion 3 and the peak portion 10 adjacent to the large diameter portion 2 is located in the radially inward region of the straight line A including the straight line A. included. Further, the straight lines (broken lines) connecting the vertices on the inner peripheral side of the valleys 11 adjacent to each other face outward in the radial direction, and unevenness is repeated alternately. Here, “the apex on the outer peripheral side” of the peak portion 10 and “the apex on the inner peripheral side” of the valley portion 11 are strictly points in contact with a straight line, and each of the maximum outer diameter of the peak portion 10, It is not necessarily the point that takes the minimum inner diameter of the valley 11.

  As described above, the three peak portions 10 sandwiched between the peak portion 10 adjacent to the small diameter portion 3 and the peak portion 10 adjacent to the large diameter portion 2 in the radially inward region of the straight line A including the straight line A. Each of the whole is included. With this configuration, centrifugal force is suppressed in the three peak portions 10, and as a result, expansion is suppressed. Moreover, since the peak part 10 adjacent to the large diameter part 2 and the peak part 10 adjacent to the small diameter part 3 are adjacent to the large diameter part 2 and the small diameter part 3, respectively, expansion | swelling of these peak parts 10 is suppressed.

  As shown in FIG. 3 in an enlarged manner, the magnitude relationship between the radial thicknesses T1 to T5 of the bent portion 11a located in the valley portion 11 is T1> T2> T3> T4> T5. The radial thickness (for example, T5) of the bent portion 11a located in at least one valley portion 11 of the large diameter portion portion R2 in the bellows portion 4 of the boot 1 is equal to at least one valley portion 11 of the small diameter portion portion R1. It is thinner than the thickness (for example, T1) of the bending part 11a located. Here, in this embodiment, the boundary between the small-diameter portion close portion R1 and the large-diameter portion close portion R2 is the axial position P at which the central peak portion 10 has the maximum outer diameter among the five peak portions 10. To do. That is, in this embodiment, the number of the valley portions 11 of the small-diameter portion portion R1 is two, but the number of the valley portions 11 of the small-diameter portion portion R1 may be three, and as such, the small-diameter portion portion R1 and the large-diameter portion What is necessary is just to set a boundary with the offset portion R2. As described above, the boundary between the small diameter portion portion R1 and the large diameter portion portion R2 and the boundary is not particularly limited, and at least one valley portion 11 is included in each of the small diameter portion portion R1 and the large diameter portion portion R2. That's fine. It should be noted that the boundary between the smaller diameter portion R1 and the larger diameter portion R2 may be the axial center of the bellows portion 4.

  In the present embodiment, the thickness relationship between the thicknesses T1 to T5 is T1> T2> T3> T4> T5, but is not limited to this relationship, and the thickness of the valley portion 11 of the portion R1 closer to the small diameter portion. It suffices if the thicknesses T3 to T5 of the valley portion 11 of the portion R2 closer to the larger diameter portion than T1 and T2 are thin.

  An annular groove 11b is formed on the outer peripheral side of the bent portion 11a of the valley portion 11 of the bellows portion 4, whereby the bent portion 11a is thinned and easily bent. The thickness (for example, TP) in the direction perpendicular to the inner peripheral surface other than the bent portion 11a in the bellows portion 4 in the large diameter portion R2 is a thickness T3 in the valley portion 11 of the large diameter portion R2. At least one of T5, eg, thicker than T5. Further, the thickness in the direction perpendicular to the inner peripheral surface of the bellows portion 4 in the bellows portion 4 in the large diameter portion portion R2 other than the bent portion 11a is the thickness T3 to T5 in the valley portion 11 in the large diameter portion portion R2. Thicker than all are desirable. Thereby, the rigidity in the large diameter part R2 of the boot 1 in the state attached in the compressed state to the constant velocity universal joint 5 becomes high, the effect | action which resists a centrifugal force increases, and the effect which suppresses expansion improves. An annular groove may be provided on the inner peripheral side of the bent portion of the peak portion 10. Thereby, the bending part of the peak part 10 becomes thin and becomes easy to bend.

  As described above, the thicknesses T3 to T5 of the valley portion 11 of the large diameter portion portion R2 are thinner than the thicknesses T1 and T2 of the valley portion 11 of the small diameter portion portion R1. With this configuration, when the boot 1 is attached to the constant velocity universal joint 5 in a compressed state, the angle of the valley portion 11 of the large-diameter portion portion R2 becomes narrower than the angle of the valley portion 11 of the small-diameter portion portion R1. When the angle of the trough part 11 is narrow, it is suppressed that the adjacent peak part 10 expand | swells. That is, it is suppressed that the peak portion 10 of the large diameter portion portion R2 expands more than the peak portion 10 of the small diameter portion portion R1. The peak portion 10 of the large diameter portion R2 is generally larger in diameter than the peak portion 10 of the small diameter portion R1 and easily receives a centrifugal force, so that it tends to expand. Therefore, it is effective to suppress the expansion of the boot 1 by suppressing the expansion of the peak portion 10 of the portion R2 near the large diameter portion. That is, with the above configuration, the expansion of the boot 1 can be effectively suppressed.

  In the said embodiment, although a constant velocity universal joint is for propeller shafts of a motor vehicle, the application object of the boot of this invention is not limited to this. For example, even a constant velocity universal joint for an industrial machine other than an automobile can be applied.

  The present invention can be variously modified within the scope of the technical idea in addition to the above embodiment.

It is an axial sectional view in the state where a constant velocity universal joint was attached to a boot for constant velocity universal joints according to an embodiment of the present invention. It is an axial sectional view in the natural state of the boot for constant velocity universal joints according to the embodiment of the present invention. FIG. 3 is an enlarged view of FIG. 2.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boots for constant velocity universal joints 2 Large diameter portion 3 Small diameter portion 4 Bellows portion 5 Constant velocity universal joint 6 Outer joint member 7 Shaft 10 Mountain portion 11 Valley portion 11a Bending portion A Straight line D1 Maximum of mountain portion Outer diameter D2 Diameter P of the tapered surface formed by the straight line Axial position R1 where the peak part takes the maximum outer diameter R1 Area near the small diameter part R2 Areas near the large diameter part T1 to T5 Radial thickness of the bent part at the valley part

Claims (9)

A boot attached to a constant velocity universal joint having an outer joint member and a shaft extending from an inner joint member arranged inward of the outer joint member, wherein the large diameter portion is attached to the outer joint member, A small-diameter portion attached to the shaft, and a bellows portion that is interposed between the small-diameter portion and the large-diameter portion and alternately has a mountain-like peak and a valley-like valley with respect to the radially outer side. In a boot for a resin constant velocity universal joint that is attached to the constant velocity universal joint in a state where the bellows portion is compressed,
In a cross section in the axial direction including the straight line connecting the apex of the crest adjacent to the small diameter portion and the apex of the crest adjacent to the large diameter portion in the axial cross section, sandwiched between the both crests Each of the entire mountains are included,
In the bellows part, the radial thickness of the bent part located in at least one valley part near the large diameter part is made thinner than the thickness of the bent part located in at least one valley part near the small diameter part, Boots for constant velocity universal joints.   The thickness of the bent part located in all the troughs near the large diameter part in the bellows part is made thinner than the thickness of the bent part located in all the trough parts near the small diameter part, etc. Fast universal joint boots.   3. The constant velocity universal joint boot according to claim 2, wherein the thickness of the bent portion located in the valley portion near the large diameter portion in the bellows portion is gradually reduced as it moves toward the large diameter portion.   The boot for a constant velocity universal joint according to claim 3, wherein the thickness of the bent portion located in the valley portion near the small-diameter portion in the bellows portion is gradually reduced as it shifts to the large-diameter portion side.   The constant velocity universal joint boot according to claim 3 or 4, wherein the largest diameter portion side of the bellows portion is a valley portion.   The boot for constant velocity universal joints as described in any one of Claims 1-5 which made the trough part near the small diameter part in the said bellows part into two or three.   The boot for constant velocity universal joints as described in any one of Claims 1-6 which made the number of the peak parts of the said bellows part five or six.   The boot for a constant velocity universal joint according to any one of claims 1 to 7, wherein the constant velocity universal joint is used for a propeller shaft of an automobile.   The constant velocity universal joint which attached the boot for constant velocity universal joints as described in any one of Claims 1-8.

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