JP2005036945A - Boot for constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize both sufficient sealing performance and excellent assembling property when a boot is fastened to a counterpart having a flat surface. <P>SOLUTION: In a boot manufactured by blow molding, when taking the opening width as w<SB>1</SB>, bottom width as w<SB>2</SB>and depth as d<SB>1</SB>in a ring groove 11 formed in the clamp groove, the relations of w<SB>1</SB>≥d<SB>1</SB>and w<SB>2</SB>=(0.2-0.8)×w<SB>1</SB>are satisfied. By so doing, the width of a seal linear protrusion 13 is prevented from becoming too wide so as to secure high surface pressure at fastening and express high sealing property. In addition, a trouble in which reaction force to a clamp is increased by abutment of both walls of the ring groove 11 can be prevented, thereby enhancing assembling property. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a boot that is covered with a constant velocity joint that is indispensable for a drive shaft joint of a front-wheel drive vehicle and prevents entry of water and dust into the joint portion of the constant velocity joint.

  The joint portion of the constant velocity joint is conventionally covered with a bellows-shaped boot, and smooth rotation at a large angle is maintained by preventing the intrusion of water and dust. This constant velocity joint boot includes a large-diameter large-diameter cylindrical portion that is held by a joint outer race, a small-diameter cylindrical portion that is smaller than the large-diameter cylindrical portion and is held by the shaft, and a large-diameter cylindrical portion and a small-diameter cylindrical portion. And a substantially frustoconical bellows portion that integrally connect the two. In use, the bellows portion is deformed according to a change in the angle (joint angle) between the joint outer race and the shaft and the joint portion can be reliably sealed by the boot even when the angle increases.

  In this constant velocity joint boot, an endless ring-shaped seal protrusion is formed on the inner peripheral surface of the large-diameter cylindrical portion, and a clamp is disposed on the outer peripheral surface of the large-diameter cylindrical portion and fastened to the mating member. The seal protrusion is elastically contacted with the mating member, and high sealing performance is exhibited.

  The boots described above can be manufactured by injection molding, but it is desirable to manufacture them by blow molding because of the molding cycle and ease of manufacture. However, in blow molding, the shape of the outer peripheral surface in contact with the mold surface can be accurately formed, but ingenuity is required to regulate the shape of the inner peripheral surface. Therefore, when a ring-shaped seal protrusion is to be formed on the inner peripheral surface of the large-diameter cylindrical portion by blow molding, for example, as described in Japanese Patent Application Laid-Open No. 02-221766, an annular protrusion is formed on the mold surface. A method is known in which a strip is formed, and a ring groove is formed on the outer circumferential surface on the opposite side of the seal projection by the annular projection. Furthermore, Japanese Patent Application Laid-Open No. 02-221766 also describes that a high sealing performance is exhibited when the ring groove is fastened to the mating member.

  Japanese Patent Application Laid-Open No. 06-341552 defines the shape of the seal ridge as a shape that is in contact with a straight line that forms an angle of 50 to 65 ° with respect to the center line orthogonal to the axial direction, and the seal ridge is formed on the outer peripheral surface. There is described a fixing structure of a boot in which a narrow ring groove is formed and fastened so that a seal protrusion is fitted into a ring groove formed on the outer peripheral surface of the mating member. If it does in this way, the press-contact part of a seal protrusion and a ring ditch | groove can be made into multiple places, and seal strength improves.

However, depending on the shape of the ring groove formed on the outer peripheral surface of the large-diameter cylindrical portion, it has been clarified that various problems occur when fastened to the mating member. For example, as shown in FIG. 11, when the width of the ring groove is relatively wide, the width of the seal protrusion formed on the inner peripheral surface at the time of blow molding becomes large, so that the surface pressure with the mating member is low at the time of fastening. As a result, sufficient sealing performance is not exhibited. Also, as shown in FIG. 10, when the width of the ring groove is relatively narrow, the width of the seal ridge is also narrowed, so that the surface pressure with the mating member is secured, but both walls of the ring groove are caused by deformation during fastening. Contact, the reaction force against the clamp increases, and the assemblability deteriorates.
JP 02-221766 JP 06-341552

  This invention is made | formed in view of such a situation, and makes it a subject to make sufficient sealing performance and favorable assembly | attachment property compatible, when fastened to the other member which has a flat surface.

The features of the constant velocity joint boot of the present invention that solves the above problems are manufactured by blow molding, and are arranged coaxially with a small diameter cylindrical portion and a small diameter cylindrical portion apart from the small diameter cylindrical portion. A cylindrical portion, and a small-diameter cylindrical portion and a large-diameter cylindrical portion are integrally connected, and a substantially frustoconical bellows portion in which crest portions and trough portions are alternately continuous, and
At least the inner peripheral surface of the large-diameter cylindrical portion has an endless ring-shaped seal protrusion, and the outer peripheral surface has a ring groove on the opposite side of the seal protrusion, and the seal protrusion is formed by clamping the outer peripheral surface. A constant velocity joint boot that is pressed against and sealed against a flat cylindrical surface of a mating member,
When w _{1 is} the opening width of the ring groove, w _{2 is} the width of the bottom of the ring groove, and d ₁ is the depth of the ring groove, w ₁ ≧ d ₁ and w ₂ = (0.2 to 0.8) × w ₁ It is to satisfy.

  The ring groove preferably has a ring-shaped taper surface that is inclined so that the groove width becomes narrower toward the bottom at the opening, and the taper surface is preferably formed on both sides of the opening.

When the ring groove has a first groove having a small width from the bottom toward the opening and a large second groove continuous with the first groove, the opening width of the second groove is set to w ₁ , and the width of the first groove. Where w ₂ , the depth of the ring groove is d ₁ , and the depth of the first groove is d ₂ , w ₁ ≧ d ₁ , w ₂ ≧ d ₂ and d ₁ = (1.2 to 2.2) × d ₂ It is preferable to satisfy the relationship.

  Furthermore, the large diameter cylindrical portion has a second ring groove between the ring groove and an end opposite to the end continuous with the bellows portion, and a second ring is formed on the inner peripheral surface of the large diameter cylindrical portion. It is preferable to have a second seal protrusion on the opposite side of the groove.

  According to the constant velocity joint boot of the present invention configured as described above, when sealed to a mating member having a flat surface, a sufficient sealing performance is exhibited because the surface pressure of the seal protrusion is high, and The reaction force to the clamp is small and good assemblability can be ensured.

In the constant velocity joint boot of the present invention, when the opening width of the ring groove is w ₁ , the width of the bottom of the ring groove is w ₂ , and the depth of the ring groove is d ₁ , w ₁ ≧ d ₁ and w ₂ = The relationship of (0.2 to 0.8) × w ₁ is satisfied. By setting w ₂ = (0.2 to 0.8) × w ₁ , the width of the seal protrusion does not become too wide, and a high surface pressure is secured at the time of fastening, and a high sealing performance is exhibited. By setting w ₁ ≧ d ₁ , the problem that both walls of the ring groove abut at the time of fastening and the reaction force to the clamp is increased is prevented, and the assembling property is improved. If w ₁ <d ₁ , the ring groove becomes too narrow and both walls of the ring groove may come into contact with each other at the time of fastening. If w ₂ is less than 0.2 times w ₁ , the reliability of the mold is lowered. The w ₂ is the surface pressure of the sealing protrusion exceeds 0.8 times w ₁ is reduced. Only when the relationship of w ₁ ≧ d ₁ and w ₂ = (0.2 to 0.8) × w ₁ is satisfied, sufficient sealability and good assemblability are compatible.

It is desirable that the ring groove has a ring-shaped tapered surface that is inclined so that the groove width becomes narrower toward the bottom at the opening. By having such tapered surfaces, w ₁ to be able to increase the narrowing to surface pressure the width of the sealing protrusion while sufficiently large, more easily and sufficient sealability and good assemblability Can be compatible. The tapered surface may be formed only on one side of the opening, but is preferably formed on both sides of the opening from the viewpoint of uniform surface pressure.

  Further, the tapered surface may be continuous from the opening to the bottom of the ring groove, or may be formed from the opening to a predetermined depth. In the latter case, the groove of the vertical wall is continuously formed from the lower end of the tapered surface.

  Further, a plurality of grooves whose widths increase in order from the bottom to the opening can be formed into a ring groove having a multi-stage shape.

For example, in the case of a ring groove having a first groove having a small width from the bottom toward the opening and a large second groove continuous with the first groove, the opening width of the second groove is w ₁ , When the width is w ₂ , the depth of the entire ring groove is d ₁ , and the depth of the first groove is d ₂ , w ₁ ≧ d ₁ , w ₂ ≧ d ₂ and d ₁ = (1.2 to 2.2) × d It is desirable to satisfy the relationship of ₂ . If w ₁ <d ₁ or w ₂ <d ₂ , the ring groove may become too narrow and the two walls of the ring groove may come into contact with each other during fastening. Further, when d ₁ is less than 1.2 times d ₂ , the reliability of the mold decreases, and when d ₁ exceeds 2.0 times d ₂ , the width of the seal protrusion becomes too large and the surface pressure decreases. Only when the relationship of w ₁ ≧ d ₁ , w ₂ ≧ d ₂ and d ₁ = (1.2 to 2.0) × d ₂ is satisfied, sufficient sealability and good assemblability are compatible.

According to blow molding, the width and height of the seal protrusion are uniquely determined by arbitrarily setting w ₁ , w ₂ , d _1, and d ₂ within the above range. Therefore, in the present invention, it is not necessary to define the shape of the seal protrusion.

  The large-diameter cylindrical portion has a second ring groove between the ring groove and an end opposite to the end continuous with the bellows portion, and a second ring is formed on the inner peripheral surface of the large-diameter cylindrical portion. It is preferable to have a second seal protrusion on the opposite side of the groove. The first seal ridge is responsible for the main seal function, but by forming a second seal ridge that also serves as axial positioning outside the first seal ridge, mud from the outside, etc. The main seal portion can be protected from contact with each other, and the reliability is greatly improved.

  The constant velocity joint boot of the present invention is manufactured by blow molding using a thermoplastic elastomer such as TPE or TPO as a raw material. The seal protrusion and the ring groove are formed at least on the large-diameter cylindrical portion, but can also be formed on the small-diameter cylindrical portion. Moreover, the diameter and thickness of a large diameter cylinder part and a small diameter cylinder part are not limited at all, and the shape of a bellows part is not limited.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. Table 1 shows the dimensions of the first ring groove 11 employed in each example and the relationship therebetween.

(Example 1)
FIG. 1 is a front view showing the constant velocity joint boot of this embodiment in a half section, FIG. 2 is an enlarged sectional view of the main part thereof, and FIG. 5 is an enlarged view of a ring groove. The boot has a large-diameter cylindrical portion 1, a small-diameter cylindrical portion 2, a small-diameter cylindrical portion 1 and a large-diameter cylindrical portion 2 that are integrally connected to each other, and a substantially frustoconical bellows portion in which peaks and valleys are alternately continued. 3 and the whole is manufactured by blow molding from TPO.

  On the outer peripheral surface of the large-diameter cylindrical portion 1, a ring-shaped clamp groove 10 with which the clamp is engaged is formed. A first ring groove 11 is formed on the outer peripheral surface of the clamp groove 10 on the inner side close to the bellows portion 3, and a second ring groove 12 is formed on the outer side thereof. The first ring groove 11 and the second ring groove 12 are formed parallel to each other along the clamp groove 10. On the inner peripheral surface of the large-diameter cylindrical portion 1, there are a first seal protrusion 13 and a second seal protrusion 14 having substantially semi-elliptical cross sections on the back surfaces of the first ring groove 11 and the second ring groove 12, respectively. Is formed. The first seal protrusion 13 and the second seal protrusion 14 are formed simultaneously with the formation of the first ring groove 11 and the second ring groove 12 during blow molding.

  A mating member 4 shown in FIG. 2 is inserted into the large-diameter cylindrical portion 1 and fastened by a clamp (not shown) mounted in the clamp groove 10. The surface to which the large-diameter cylindrical portion 1 of the counterpart member 4 is fastened is a cylindrical surface, and a positioning groove 40 is formed in a part thereof. The second seal protrusion 14 is engaged with the positioning groove 40 to perform insertion positioning, and the first seal protrusion 13 is pressed against a flat cylindrical surface, so that most of the sealing performance is exhibited. . The first seal protrusion 13 is responsible for the main seal function, but the second seal protrusion 14 that also serves as the axial positioning is formed by the first seal protrusion 13 and the end of the large-diameter cylindrical portion 1. The main seal portion is protected so as not to come into contact with muddy water from the outside.

  Here, the first ring groove 11 has a first groove 15 having a small width from the bottom toward the opening, and a large second groove 16 continuing to the first groove 15. The second groove 16 is formed from the opening end to a depth of 0.4 mm, and both wall surfaces thereof are tapered surfaces 17 inclined at 45 ° so that the groove width becomes narrower toward the bottom.

As shown in Table 1, the first ring groove 11 has an overall depth (d ₁ ) of 1.1 mm, an opening width (w ₁ ) of the second groove 16 of 1.5 mm, and an opening of the first groove 15. The width (w ₂ ) is 0.7 mm, and the depth (d ₂ ) of the first groove 15 is 0.7 mm. That is, w ₁ > d ₁ , w ₂ = d ₂ , w ₂ = 0.47 × w ₁ and d ₁ = 1.57 × d ₂ .

(Comparative Example 1)
FIG. 10 shows an enlarged cross-sectional view of the main part of the constant velocity joint boot of this comparative example. This boot has the same shape as that of Example 1 except that the shapes of the first ring groove 11 and the first seal protrusion 13 are different, and was similarly manufactured by blow molding from the same material.

As shown in Table 1, the first ring groove 11 has an opening width (w ₁ ) of 0.5 mm, a uniform width from the opening to the bottom, and a depth (d ₁ ) of 1.5 mm.

(Comparative Example 2)
FIG. 11 shows an enlarged cross-sectional view of the main part of the constant velocity joint boot of this comparative example. This boot has the same shape as that of Example 1 except that the shapes of the first ring groove 11 and the first seal protrusion 13 are different, and was similarly manufactured by blow molding from the same material.

As shown in Table 1, the first ring groove 11 has an opening width (w ₁ ) of 1.5 mm, a uniform width from the opening to the bottom, and a depth (d ₁ ) of 1.1 mm.

<Test and evaluation>
For the boots of Example 1, Comparative Example 1 and Comparative Example 2, the maximum surface pressure and the reaction force to the clamp when fastened to the mating member with various tightening margins were calculated by FEA. The results are shown in FIGS.

According to this calculation, the boot of Example 1 exhibits a high surface pressure equivalent to that of Comparative Example 1 and has a reaction force equivalent to that of Comparative Example 2. That is, the first ring groove 11 is fastened to a mating member having a flat surface by satisfying the relationship of w ₁ ≧ d ₁ , w ₂ ≧ d ₂ and d ₁ = (1.2 to 2.2) × d _2. It is clear that sufficient sealability and good assemblability are compatible.

(Example 2)
FIG. 3 shows an enlarged cross-sectional view of the main part of the constant velocity joint boot of this embodiment, and FIG. 6 shows an enlarged view of the ring groove. Show. This boot had the same shape as in Example 1 except that the shape of the first ring groove 11 was different, and was manufactured by blow molding from the same material.

As shown in Table 1, the first ring groove 11 has an opening width (w ₁ ) of 1.5 mm, a bottom width (w ₂ ) of 0.5 mm, and both wall surfaces from the opening to the bottom are tapered surfaces 17. Yes. The total depth (d ₁ ) is 1.1 mm.

When the boot of this example was evaluated in the same manner as described above, a result equivalent to that of Example 1 was shown. That is, when the shape of the first ring groove 11 satisfies the relationship of w ₁ ≧ d ₁ and w ₂ = (0.2 to 0.8) × w ₁ , it is sufficient when fastened to a mating member having a flat surface. It is clear that the sealing property and the good assembly property are compatible.

(Example 3)
FIG. 4 shows an enlarged cross-sectional view of the main part of the constant velocity joint boot of this embodiment, and FIG. 7 shows an enlarged view of the ring groove. Show. This boot had the same shape as in Example 1 except that the shape of the first ring groove 11 was different, and was manufactured by blow molding from the same material.

The first ring groove 11 includes a first groove 15 having a small width from the bottom toward the opening, and a large second groove 16 continuing to the first groove 15. The second groove 16 is formed from the opening end to a depth of 0.6 mm. As shown in Table 1, the first ring groove 11 has an overall depth (d ₁ ) of 1.1 mm, an opening width (w ₁ ) of the second groove 16 of 1.5 mm, and an opening width of the first groove 15. (W ₂ ) is 0.5 mm, and the depth (d ₂ ) of the first groove 15 is 0.5 mm. That is, the relationship is w ₁ > d ₁ , w ₂ = d ₂ , w ₂ = 0.33 × w ₁ and d ₁ = 2.2 × d ₂ .

When the boot of this example was evaluated in the same manner as described above, a result equivalent to that of Example 1 was shown. That is, the shape of the first ring groove 11 satisfies the relationship of w ₁ ≧ d ₁ , w ₂ ≧ d ₂ , w ₂ = (0.2 to 0.8) × w ₁ , d ₁ = (1.2 to 2.2) × d _2. Thus, when fastened to a mating member having a flat surface, it is clear that sufficient sealing properties and good assembling properties are compatible.

  That is, if the present invention is used, it is possible to stably produce a constant velocity joint boot that has both sufficient sealing performance and good assembly performance by blow molding. Therefore, productivity is improved, and it is a cheap and reliable boot for a constant velocity joint, and the cost of a vehicle equipped with the boot is reduced.

It is a front view shown with a half section of a boot for constant velocity joints of one example of the present invention. It is a principal part expanded sectional view of FIG. 1 shown with a mating member. It is a principal part expanded sectional view of the boot for constant velocity joints of Example 2 of this invention. It is a principal part expanded sectional view of the boot for constant velocity joints of Example 3 of this invention. FIG. 3 is an enlarged view of a first ring groove of the constant velocity joint boot according to the first embodiment. 6 is an enlarged view of a first ring groove of a constant velocity joint boot of Example 2. FIG. 6 is an enlarged view of a first ring groove of a constant velocity joint boot of Example 3. FIG. It is a graph which shows the relationship between interference and maximum surface pressure. It is a graph which shows the relationship between interference and clamp reaction force. 3 is an enlarged cross-sectional view of a main part of a constant velocity joint boot of Comparative Example 1. FIG. 6 is an enlarged cross-sectional view of a main part of a constant velocity joint boot of Comparative Example 2. FIG.

Explanation of symbols

1: Large diameter cylindrical portion 2: Small diameter cylindrical portion 3: Bellows portion 4: Counterpart member 10: Clamp groove 11: First ring groove
13: 1st seal protrusion 15: 1st groove 16: 2nd groove

Claims (5)

Manufactured by blow molding, a small-diameter cylindrical portion, a large-diameter cylindrical portion that is coaxially disposed apart from the small-diameter cylindrical portion, and has a larger diameter than the small-diameter cylindrical portion, and the small-diameter cylindrical portion and the large-diameter cylindrical portion And a substantially frustoconical bellows portion that is integrally connected and has alternating peaks and troughs,
At least the inner peripheral surface of the large-diameter cylindrical portion has an endless ring-shaped seal ridge, and the outer peripheral surface has a ring groove on the opposite side of the seal protrusion. A boot for a constant velocity joint in which a seal protrusion is pressed and sealed against a flat cylindrical surface of a mating member,
When the opening width of the ring groove is w ₁ , the width of the bottom of the ring groove is w ₂ , and the depth of the ring groove is d ₁ , w ₁ ≧ d ₁ and w ₂ = (0.2 to 0.8) × w A constant velocity joint boot characterized by satisfying the relationship of ₁ .   2. The constant velocity joint boot according to claim 1, wherein the ring groove has a ring-shaped taper surface that inclines so that the groove width becomes narrow toward the bottom at the opening.   The constant velocity joint boot according to claim 2, wherein the tapered surface is formed on both sides of the opening. The ring groove has a first groove having a small width from the bottom toward the opening and a large second groove continuous with the first groove. The opening width of the second groove is w ₁ , and the width of the first groove. Is w ₂ , the depth of the ring groove is d ₁ , and the depth of the first groove is d ₂ , w ₁ ≧ d ₁ , w ₂ ≧ d ₂ and d ₁ = (1.2 to 2.2) × d _The boot for a constant velocity joint according to any one of claims 1 to 3, which satisfies the relationship of ₂ .   The large-diameter cylindrical portion has a second ring groove between the ring groove and an end opposite to the end continuous with the bellows portion, and the inner peripheral surface of the large-diameter cylindrical portion has the The boot for a constant velocity joint according to claim 1, wherein the second seal groove has a second seal protrusion on the opposite side of the second ring groove.

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