JP2007211959A - Boot for constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance durability of a boot in a case of using for a constant velocity universal joint corresponding to high operation angle. <P>SOLUTION: A boot for a constant velocity universal joint is the boot which includes a crest part, a trough part and a slant part. The relationship, t<SB>n</SB><T<SB>a</SB>, is satisfied at least at an arbitrary pair of the slant parts when the central wall thickness of the slant part on side of a smaller diameter and the central wall thickness of the slant part on side of a larger diameter part of a pair of slant parts of which insides are opposed to each other are represented by T<SB>n</SB>and t<SB>n</SB>, respectively. The relationship, t<SB>n</SB>≤T<SB>n</SB>, is satisfied at the slant part which makes the other pair, and the relationship, R<SB>1</SB>≤R<SB>2</SB>≤...≤R<SB>n-2</SB><R<SB>n-1</SB>≤R<SB>n</SB>, is satisfied when the wall thickness of the trough part is represented by R<SB>n</SB>. The following relationships are satisfied when the wall thickness of the crest part is represented by P<SB>n</SB>. When the bellows part is composed of the following number of the crests, P<SB>2</SB><P<SB>1</SB><P<SB>3</SB>≤P<SB>4</SB>in 4 crests, P<SB>2</SB><P<SB>1</SB>≤P<SB>3</SB><P<SB>4</SB>≤P<SB>5</SB>in 5 crests, P<SB>2</SB><P<SB>1</SB>≤P<SB>3</SB><P<SB>4</SB>≤P<SB>5</SB>≤P<SB>6</SB>in 6 crests, P<SB>2</SB><P<SB>1</SB>≤P<SB>3</SB>≤P<SB>4</SB><P<SB>5</SB>≤P<SB>6</SB>≤P<SB>7</SB>in 7 crests, P<SB>2</SB><P<SB>1</SB>≤P<SB>3</SB>≤P<SB>4</SB><P<SB>5</SB>≤P<SB>6</SB>≤P<SB>7</SB>≤P<SB>8</SB>in 8 crests and P<SB>2</SB><P<SB>1</SB>≤P<SB>3</SB>≤P<SB>4</SB>≤P<SB>5</SB><P<SB>6</SB>≤P<SB>7</SB>≤P<SB>8</SB>≤P<SB>9</SB>in 9 crests are formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a boot covering a constant velocity universal joint used for a drive shaft of an automobile, and more particularly to improve durability such as wear and fatigue when mounted on a joint for high working angle. The present invention relates to a boot for a constant velocity universal joint that can reliably maintain a stable boot deformation state.

  A boot is attached to the constant velocity universal joint for the purpose of preventing leakage of grease sealed inside to the outside and preventing entry of foreign matter from the outside. This constant velocity universal joint boot includes a large diameter portion attached to a boot mounting portion provided at an opening end portion of an outer joint member of the constant velocity universal joint, and a drive shaft connected to the inner joint member of the constant velocity universal joint. A small-diameter portion mounted on the (shaft) and a bellows portion integrally connecting the two attachment portions. The constant velocity universal joint has a function of rotating while taking an operating angle or rotating while sliding in the axial direction, and has a bellows shape to ensure the flexibility of the boot that can follow its behavior. ing. The constant velocity universal joint boot includes a rubber boot such as chloroprene rubber and a resin boot using a thermoplastic elastomer material. Resin boots are expanding their application because they are superior to rubber boots in terms of fatigue, wear, and high-speed rotation (running performance during rotation). In particular, in the boots for constant velocity universal joints used on the front wheel side of automobiles that require a large operating angle, resin boots that exhibit excellent performance as described above are the mainstream. Regarding the shape and thickness of the resin boot, for example, inventions according to Patent Documents 1 to 5 have been proposed.

JP 2002-257152 A Japanese Utility Model Publication No. 6-82463 JP-A-6-129536 Japanese Patent Laid-Open No. 7-259993 Japanese Utility Model Publication No. 7-10561

  The constant velocity universal joint boot is deformed to follow the movement of the constant velocity universal joint that takes an operating angle or slides. Along with the deformation, wear occurs due to interference between adjacent peaks, or wear due to interference between the inner surface of the valley and the shaft. Alternatively, fatigue cracks may occur due to repeated generation of stress in the peaks and valleys. As they progress, the boot may be damaged. Further, when the joint takes a high operating angle, the boot is greatly deformed, and the bellows is not easily folded, and the bellows part may be recessed. The boot is required to have a design that can further improve the durability such as wear and fatigue and can maintain a stable boot deformation state.

  In Patent Document 1, the rigidity of the bellows portion composed of six or more peaks / valleys is the center portion> the portion near the large diameter mounting portion> the portion near the small diameter mounting portion, and the thickness of at least one of the valley portion and the mountain portion is It is disclosed that the magnitude relationship is the order described above. Further, it is disclosed that the curvature radius of the valley portion of the central portion is larger than the curvature radius of the other valley portions.

  Patent document 2 is disclosing gradually increasing the trough thickness of a boot bellows part toward a large diameter part.

  Patent Document 3 is composed of 6 to 8 ridges, and the thickness from 1 to 4 ridges counted from the large-diameter fixed portion is 1.1 to 1.6 mm, and from the large-diameter fixed portion to 1 to 3 valleys. It is disclosed that the wall thickness is substantially the same as or slightly thicker from 1 to 4 peaks.

In Patent Document 4, the minimum peak thickness is less than 2.3 times the maximum valley thickness, and the maximum peak thickness is less than 1.25 mm. The peak maximum thickness is set to 0.8 to 1.25 times the valley minimum thickness. Furthermore, it discloses that the valley has a U-shaped cross-sectional shape, and the entire bellows is constituted by three zones.

  Patent document 5 is a boot having a bellows part, and the distance between each mountain part and each valley part connected to this is substantially the same, and each mountain part and each mountain connected to the small diameter part side from the valley part. It is disclosed that the ratio of the step difference in the radial direction with respect to the portion is in the range of 26 to 36%, and the thickness of each peak portion is in the range of 60 to 100% of the thickness of each valley portion connected to the peak portion. .

However, it cannot be said that the above-mentioned boot can exhibit sufficient performance in terms of wear and fatigue. In addition, it is difficult to ensure a stable boot deformation state, and a dent may be formed in the bellows part particularly at a high operating angle. In order to solve these problems, a boot design lacking compactness must be taken.
The present invention prevents the wear and fatigue of the boot when used in a constant velocity universal joint for high operating angle, and further prevents the depression of the bellows portion, thereby improving the durability of the boot for the constant velocity universal joint. It is in.

In order to solve the above problems, the invention according to claim 1 is configured such that a torque transmission member is accommodated between an outer joint member and an inner joint member, and a shaft connected to the inner joint member extends outside the joint. The constant velocity universal joint is a boot disposed between the outer periphery of the outer joint member and the outer periphery of the intermediate portion of the shaft, and is a cylindrical large member fixed to the outer peripheral surface of the outer joint member with a boot band. A diameter portion, a cylindrical small diameter portion fixed to the outer peripheral surface of the shaft, and a bellows portion connecting between the large diameter portion and the small diameter portion, the bellows portion including a plurality of peaks, a plurality of valleys, and The center wall thickness of the slope portion on the small diameter portion side of the pair of slope portions that are composed of a plurality of slope portions connecting the mountain portion and the valley portion and the inner surfaces face each other is T _n , and the center of the slope portion on the large diameter portion side when the thickness was _{t n,} a _t n _{<T n} at least any pair of slope portions, One, when the relationship is _{t n} ≦ _{T n} is the slope portion forming any other pair, the thickness of the valley and the _{R n, R 1 ≦ R 2} ≦ ... ≦ R N-2 <R N-1 a relation of ≦ R _n, and, when the thickness at the crest and the P _n, boot for a constant velocity universal joint and satisfies the following relationship.
When the bellows part is composed of four mountain parts, P ₂ <P ₁ <P ₃ ≦ P _4, (1),
When the bellows part is composed of five mountain parts, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ (2),
When the bellows part is composed of six mountain parts, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ ≦ P ₆ (3),
When the bellows portion is composed of seven peak portions, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ <P ₅ ≦ P ₆ ≦ P ₇ (4),
When the bellows part is composed of eight mountain parts, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ <P ₅ ≦ P ₆ ≦ P ₇ ≦ P ₈ (5),
When the bellows portion is composed of nine peak portions, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ ≦ P ₅ <P ₆ ≦ P ₇ ≦ P ₈ ≦ P ₉ (6), (subscript n: small diameter portion The order of the mountains counted from the side, the suffix: the order of the mountains or valleys counted from the small diameter part side, N: the total number of valleys).

  Although the present invention is basically applied to boots having 4 to 9 peaks, the invention can be similarly applied to boots having 10 or more peaks. In that case, the law expressed by the relational expressions (1) to (6) is also applied to boots having 10 or more peaks.

The concept of the relational expressions (1) to (6) is as follows. That is, a plurality of peaks are classified into two groups: a peak on the small diameter side and a peak on the large diameter side. In this case, if the total number of peaks is an odd number, the peak located in the middle is on the small diameter side. The ridge thickness is the small-diameter-side ridge group thickness <the large-diameter-side ridge group thickness, and the large-diameter-side ridge thickness is on the large-diameter side. As you go, it must be the same or thicker than the thickness of the mountain in front of you. Furthermore, 2 YamanikuAtsu P ₂ of the second small-diameter portion has to be the thinnest wall thickness. From the above regularity, for example, in the case of a four-crest structure, P ₂ <P ₁ <P ₃ ≦ P ₄ (formula (1)). In the case of a five-crest structure, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ (formula (2)). In the six-crest structure, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ ≦ P ₆ (the above expression (3)). The above relational expression is derived from this concept.

  The invention according to claim 2 is the invention according to claim 1, wherein the ridge portion of the bellows portion is equally divided into the small diameter portion side ridge portion group and the large diameter portion side ridge portion group by the number of ridge portions, wherein the number of ridge portions is an odd number. When the central ridge is classified into the small-diameter-side ridge group, the ridge thickness excluding the second ridge from the small-diameter side in the small-diameter-side ridge group is adjacent to both sides of the ridge. The peak thickness of the large-diameter side peak portion group is greater than the thickness of the valley portion adjacent to both sides of the peak portion.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein, in all slope parts connecting the peak part and the valley part of the bellows part, the intersection angle between the small diameter part side slope and the shaft center line with the valley part as the center. (Β) is smaller than an intersection angle (α) between the large-diameter portion side slope and the shaft center line.

  The invention of claim 4 is characterized in that, in the invention of any one of claims 1 to 3, the valley section has a U-shaped cross section.

  The invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the boot is made of a thermoplastic polyester elastomer having a hardness of 35 or more and 50 or less as measured by a type D durometer as defined in JIS K6253. is there.

  The invention of claim 6 is a fixed type constant velocity universal joint to which any one of the boots of claims 1 to 5 is attached.

  According to the present invention, when the constant velocity universal joint takes an operating angle, the interference pressure between the peaks when the boot is deformed, the interference pressure between the valley and the shaft, and the stress concentration on the boot valley are effective. It is possible to achieve equalization by dispersing in a boot, and the wear and fatigue properties of the boot can be improved. In addition, the boot can be flexibly deformed even at a high operating angle, and the shape can be firmly maintained, and the depression of the bellows can be prevented. With these effects, it becomes possible to obtain a boot for a constant velocity universal joint having superior durability, or it is possible to achieve a compact boot as a whole with equivalent durability. .

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
FIG. 1 shows a half cross section of a boot 1 for a constant velocity universal joint according to an embodiment of the present invention. The overall schematic shape of the boot 1 is substantially the same as the conventional one, and a large-diameter portion 1a fixed to the outer peripheral surface of the outer joint member of the constant velocity universal joint and a small-diameter portion fixed to the outer peripheral surface of the shaft of the constant velocity universal joint. The boot 1 is comprised by 1b and the bellows part 1c which connects between a large diameter part and a small diameter part. The boot 1 is formed from a resin material such as a thermoplastic elastomer (TPE).

  The bellows portion 1 c is composed of about four to nine peaks 5, valleys 6 between the peaks 5, and slopes 7 connecting the peaks 5 and the valleys 6. Further, the valley portion 6 on the largest diameter side is connected to a portion called a large diameter shoulder portion 1d connected to the large diameter portion 1a via an inclined surface 7a. The large-diameter shoulder 1d is distinguished from the peak 5.

The peak portion 5 is referred to as one mountain, two peaks,... Sequentially from the small diameter portion 1b side, and the valley portion 6 is referred to as one valley, two valleys,. The vertical thickness of one mountain is “P ₁ ”, the vertical thickness of two peaks is “P ₂ ”, and so on. Also, the vertical thickness of one valley is “R ₁ ”, the vertical thickness of two valleys is “R ₂ ”, and so on. Furthermore, the thickness near the center of the slope on the small diameter side of the two mountains is “T ₂ ”, and the thickness near the center on the slope on the large diameter side of the two mountains is “t ₂ ”. The thickness is “T ₃ ”, the thickness near the center of the slope on the large diameter side of the three peaks is “t ₃ ”, and so on.
The boot of the present invention has T ₂ ≧ t ₂ , T ₃ ≧ t ₃ , T ₄ ≧ t ₄ ,..., And at least at one location, the wall thickness near the center of the small-diameter portion side slope has a large diameter. It must be thicker than the wall thickness near the center of the slope.

Further, the valley thickness is R ₁ ≦ R ₂ ≦ R ₃ ≦ R ₄ ≦ R ₅ ≦... And the two valley thicknesses from the large diameter side are larger than the other valley thicknesses. Must also be thick. That is, in the case of four valleys 6, R ₁ ≦ R ₂ <R ₃ ≦ R ₄ , and in the case of five valleys 6, R ₁ ≦ R ₂ ≦ R ₃ <R the ₄ ≦ _{R 5.}

  Further, when the plurality of ridges 5 are classified into two groups of a plurality of ridges on the small diameter side and a plurality of ridges on the large diameter side (when the number of ridges is an odd number, The ridge thickness is smaller than the smaller-diameter-side ridge group thickness <large-diameter-side ridge-group thickness, and the larger-diameter-side ridge thickness is large. As you go to the diameter side, it must be the same as or thicker than the thickness of the front mountain.

In addition, 2 YamanikuAtsu P ₂ is, must be the most thin wall thickness.
From the above regularity, in the case of the four mountain structure, P ₂ <P ₁ <P ₃ ≦ P ₄ . In the case of the five-crest structure in FIG. 1, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ is satisfied. In the six-crest structure, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ ≦ P ₆ .

  The mountain group thickness on the large diameter side is preferably 1.1 to 1.4 times the thickness of the mountain group except for two peaks on the small diameter side. If it is less than 1.1 times, the effect of improving the durability is poor, and if it exceeds 1.4 times, the durability deteriorates on the contrary, or even if it does not deteriorate, the weight of the boot increases.

  Further, the small-diameter side ridge portion thickness excluding two ridges is equal to or thicker than the adjacent valley thickness, and the large-diameter side ridge thickness is adjacent to the valley portion. It must be thicker than the wall thickness. The large-diameter side ridge portion wall thickness is preferably 1.1 times or more that of the thinner adjacent valley portion. If it is less than 1.1 times, it is difficult to expect a sufficient improvement in durability.

  On the other hand, there is an important feature regarding the shape design of the slope. For example, 2 valleys are composed of a 3 mountain small diameter side slope connected to 3 mountains and a 2 mountain large diameter side slope connected to 2 mountains. The intersection angle between the three small-diameter side slopes and the shaft centerline 8 when no external force is applied to the boot is “α”, and the intersection angle between the two large-diameter side slopes and the shaft centerline is “β” (both In the case of an acute angle side), α> β must be satisfied. Thereby, when the joint takes a high operating angle, the valley is smoothly folded while inclining to the large diameter side, so that the contact force applied to the slope and the stress applied to the peak / valley are evenly distributed. Slope wear and mountain / valley fatigue are improved. Further, since the deformed state is stabilized, the depression of the bellows portion can be further prevented.

  This relationship is necessary in all the valleys 6 constituting the boot. Moreover, it is preferable that all α and all β each show substantially the same angle, and the difference is preferably within a range of ± 10 °. As a result, the deformation state when the high operating angle is taken is more evenly maintained throughout the bellows, so that the contact force applied to the slope and the stress applied to the peaks and valleys are evenly distributed. And fatigue of mountains and valleys are improved. Further, since the deformed state is stabilized, the depression of the bellows portion can be further prevented.

  In addition, it is preferable that the trough part 6 has comprised the U-shaped cross-sectional shape, and can improve durability more.

  The present invention is a type that can take a high operating angle of θ = 45 deg or more (for example, a fixed type constant velocity universal joint using a ball such as a Rzeppa type or a Barfield type), and an axial direction of an outer joint member. It can be applied to boots used in all constant velocity universal joints, such as a type with a sliding mechanism (for example, double offset type, tripod type, cross groove type, etc.). It is more effective to apply to a type that can take a large operating angle of the joint, and it is particularly effective to apply to a fixed type constant velocity universal joint.

  This shape discloses the shape of a resin boot using a thermoplastic elastomer material, and in particular, a thermoplastic polyester elastomer having a hardness of 35 or more and 50 or less according to a type D durometer defined in JIS K6253. The present invention can be more suitably applied to boots made from steel.

  By applying the bellows shape according to the present application, boot durability such as wear between mountains, wear between valleys and shafts, and fatigue between peaks and valleys is improved. Further, the dent resistance can be improved, the well-balanced boot performance can be maintained, and the boot can be further downsized.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made based on the technical idea included in the claims.

  The constant velocity universal joint boot of the present invention is a type that can take a large operating angle of 45 ° or more, for example, a fixed type constant velocity universal joint using a ball such as a Zepper type or a barfield type, or an outer joint. Applicable to boots used for all constant velocity universal joints such as sliding type constant velocity universal joints such as double offset type, tripod type, cross groove type, etc. .

The half sectional view of the boot for constant velocity universal joints concerning the embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Constant velocity universal joint boot 1a Large diameter part 1b Small diameter part 1c Bellows part 1d Shoulder part 5 Mountain part 6 Valley part 7 Slope 8 Shaft centerline

Claims (6)

A torque transmission member is accommodated between the outer joint member and the inner joint member, and a shaft connected to the inner joint member extends outside the joint. A boot disposed between the outer periphery of the intermediate portion of the shaft, a cylindrical large-diameter portion fixed to the outer peripheral surface of the outer joint member with a boot band, and a cylindrical shape fixed to the outer peripheral surface of the shaft A small bellows portion and a bellows portion connecting the large diameter portion and the small diameter portion, and the bellows portion includes a plurality of mountain portions, a plurality of valley portions, and a plurality of slope portions connecting the mountain portions and the valley portions. And
Of the pair of slopes facing the inner surfaces, when the central thickness of the slope part on the small diameter side is T _n and the center thickness of the slope part on the large diameter part side is t _n , at least any pair of slope parts a t _{n <T n,} and the relationship is _{t n} ≦ _{T n} is the slope portion forming any other pair,
When the thickness of the valley is R _n , the relation of R ₁ ≦ R ₂ ≦... ≦ R _N−2 <R _N−1 ≦ R _N , and
A constant velocity universal joint boot characterized by satisfying the following relationship when the thickness of the mountain portion is _Pn .
When the bellows part is composed of four peak parts, P ₂ <P ₁ <P ₃ ≦ P _4,
When the bellows part is composed of five mountain parts, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅
When the bellows part is composed of six mountain parts, P ₂ <P ₁ ≦ P ₃ <P ₄ ≦ P ₅ ≦ P ₆
When the bellows portion is composed of seven peak portions, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ <P ₅ ≦ P ₆ ≦ P ₇
When the bellows part is composed of eight peak parts, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ <P ₅ ≦ P ₆ ≦ P ₇ ≦ P ₈
When the bellows portion is composed of nine peak portions, P ₂ <P ₁ ≦ P ₃ ≦ P ₄ ≦ P ₅ <P ₆ ≦ P ₇ ≦ P ₈ ≦ P ₉
(Subscript n: Order of mountains counted from the small diameter part side, Subscript number: Order of mountains or valleys counted from the small diameter part side, N: Total number of valleys)   Divide the bellows peak into a small diameter side peak group and a large diameter side peak group equally by the number of peaks, and if the number of peaks is odd, classify the central peak into the small diameter side peak group The ridge thickness excluding the second ridge from the small-diameter portion side in the small-diameter-side ridge portion group is equal to or greater than the valley thickness adjacent to both sides of the ridge, and the large-diameter 2. The constant velocity universal joint boot according to claim 1, wherein a thickness of the peak portion of the portion side peak portion group is larger than a thickness of a valley portion adjacent to both sides of the peak portion. In all the slopes connecting the peaks and valleys of the bellows part, the intersection angle (β) between the small-diameter side slope and the shaft centerline with respect to the valley is the center of the large-diameter side slope and the shaft centerline. The constant velocity universal joint boot according to claim 1, wherein the boot is equal to or smaller than an intersection angle (α). The constant velocity universal joint boot according to any one of claims 1 to 3, wherein the valley section has a U-shaped cross section. The boot for a constant velocity universal joint according to any one of claims 1 to 4, wherein the boot is made of a thermoplastic polyester elastomer having a hardness of 35 or more and 50 or less according to a type D durometer defined in JIS K6253. A fixed type constant velocity universal joint equipped with the constant velocity universal joint boot according to claim 1.

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