JP2006090391A - Boot for constant velocity joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lightweight, compact boot for a constant velocity joint suitable for high speed rotation. <P>SOLUTION: The boot 1 is provided with a large diameter cylinder section 2 mounted on an end of an outer ring A of the constant velocity joint, a small diameter cylinder section 3 mounted on a boot connecting section of a shaft B, and a film-shaped section 4 integrally coupling both cylinder sections 2 and 3. The boot is made from a material having a high elastic limit property, and a shape and wall-thickness of the film-shaped section 4 are set up at the basis of the high elastic limit property. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a constant velocity joint boot used in automobiles, industrial machines, and the like.

  A constant velocity joint for automobiles or the like is equipped with a boot for the purpose of preventing leakage of grease sealed inside to the outside and preventing foreign matter from entering the constant velocity joint. This boot has a large-diameter cylindrical portion that is attached to the boot attachment portion provided at the outer ring end of the constant velocity joint, and a small-diameter cylindrical portion that is attached to the boot attachment portion provided on the shaft connected to the constant velocity joint. , And a bellows-like portion that integrally connects both cylindrical portions.

The constant velocity joint has a function of rotating while taking an operating angle or rotating while sliding in the axial direction, and the flexibility of the boot that can follow the behavior is required. In order to ensure the flexibility, the conventional boot has a bellows shape (for example, Patent Document 1).
JP 2001-65594 A

In recent years, constant velocity joints for automobile parts and the like are strongly demanded to be lightweight and compact, and similarly, constant velocity joint boots are also required to be lightweight and compact. However, the conventional constant velocity joint boot has a bellows shape in order to cope with the behavior of the constant velocity joint as described above. Therefore, by taking the operating angle, the ridges come into contact with each other and wear, or the valleys come into contact with the shaft, so that the boots reach the end of their life early. Or a crack may generate | occur | produce when stress concentrates on the trough part and peak part which are the bending points of a bellows, and a boot may be brought to life early.
In order to avoid these problems, a boot design with a large outer shape is adopted. As a result, the boot capacity is increased, the boot weight is increased, the amount of grease enclosed in the constant velocity joint is increased, and the grease weight is increased. There is a problem that said it will be heavy.

  In addition, since the boot is not compact, there is a problem in securing clearance with peripheral members. Furthermore, due to the increase in the amount of grease filled due to the increase in the outer diameter of the boot and the increase in the volume, the centrifugal force during rotation increases, so that the amount of run-out during rotation, that is, the amount of expansion deformation (hereinafter referred to as the amount of expansion deformation) (Referred to as “rotational expansion amount”), so that interference is likely to occur, and the maximum limit rotational speed is suppressed.

  An object of the present invention is to provide a constant velocity joint boot that is lightweight and compact and suitable for high-speed rotation.

The constant velocity joint boot of the present invention uses a material having a high elastic limit characteristic, and the shape and thickness of the boot are set based on the high elastic limit characteristic.
By setting the boot shape and wall thickness based on the high elastic limit characteristics, it is possible to change the operating angle of the constant velocity joint with a simple cross-sectional shape with few irregularities, or even slide, etc. without adopting the bellows shape The boot can follow the behavior. Therefore, the creeping length (that is, the length along the surface) of the film-like portion is shortened, so that the boot can be reduced in weight and compactness can be achieved. Due to this compactness, the amount of grease charged in the constant velocity joint can be reduced. As a result, the amount of rotational expansion can be reduced, and the maximum limit rotational speed can be increased. Further, since there is no bellows shape, even if the operating angle is taken, the contact between the boot and the shaft or the outer inner surface of the boot can be prevented or reduced, so that wear can be eliminated. Since no wear occurs, wear resistance is not required, and the selection range of materials having high elastic limit properties is expanded.

  The elastic limit is also called an elastic limit or an elastic limit. In addition, the high elasticity limit in this specification means that a constant velocity joint can be used even if the boot made of the material is flatter than the bellows shape, that is, not in a bent shape having a large number of peaks and valleys. The boots can follow the behavior of the body and the elasticity limit is as high as possible.

Specifically, the boot for the constant velocity joint of the present invention, specifically, a large diameter cylindrical portion attached to the outer ring end portion of the constant velocity joint, a small diameter cylindrical portion attached to the boot fitting portion of the shaft of the constant velocity joint, In a constant velocity joint boot comprising a membrane-like portion integrally connecting both cylindrical portions, a material having a high elastic limit property is used for the membrane-like portion, and based on the high elastic limit property, The shape and thickness are set.
The entire boot need not necessarily have a high elastic limit property, and any material having a high elastic limit property may be used for the film-like portion. The large-diameter cylindrical portion and the small-diameter cylindrical portion do not need high elastic limit characteristics, and the boot may be formed so that the material differs depending on the portion. Further, the film-like portion and the like may be made of different materials in layers inside and outside.

The degree of the high elastic limit property is preferably a property in which the modulus up to 160% or more in the strain-stress curve has a positive first-order gradient, and more preferably 250% or more. In the following description, the elastic limit will be described by the maximum elongation ratio indicating the primary gradient.
In the conventional general boot material, the elastic limit is about 120%, but in order to make the boot capable of following the behavior of the constant velocity joint, it is necessary to adopt a bellows shape. Absent. If the elastic limit is about 160% or more, the boot can follow the behavior of the constant velocity joint even if it has a conical shape, for example, without the bellows shape.

Other constant velocity joint boots in this invention are a large diameter cylindrical portion attached to the outer ring end of the constant velocity joint, a small diameter cylindrical portion attached to the boot fitting portion of the shaft of the constant velocity joint, and both the cylindrical portions. In a constant velocity joint boot comprising a membrane-like portion integrally connecting the membrane-like portion, a material having a high elastic limit property is used for the membrane-like portion, and the membrane-like portion takes a maximum operating angle. And the shaft do not interfere with each other, or are not in contact with each other at any two locations of the boot itself.
Some general-purpose rubber materials have an elastic limit of several hundred percent, but boots are required to have heat resistance, cold resistance, fatigue resistance, oil resistance, etc. Since wear resistance is required, the range of materials that can be used is limited, and it is difficult to select materials having high elastic limit properties. Even if new materials are developed, there are many requirements and development is difficult. However, if the constant velocity joint is at the maximum operating angle, the boot membrane and the shaft do not interfere with each other, or if the boot has a shape that does not cause mutual contact at any two locations on the boot itself, interference occurs. Or, wear resistance considering the occurrence of contact is not necessary. For this reason, the selection range of the material is expanded, and it is possible to select a material having a high elastic limit property that can adopt a shape that does not cause the interference and contact, or to realize the development of such a material.

  In this case, the material of the film-like portion of the boot may be a material having wear resistance required by the occurrence of the interference or contact, but has excellent wear resistance to this extent. It may be a material that does not. If there is a material having the high elastic limit property among the materials having no wear resistance, the material may be used.

The material selection method for the constant velocity joint boot of the present invention includes a step of selecting heat resistance, a step of selecting cold resistance, a step of selecting fatigue resistance, a step of selecting oil resistance, and a high elastic limit. Selecting a characteristic. The order of the steps may be interchanged with each other, may be performed simultaneously, or any one or more steps may be repeated.
The material selection method of the present invention is a method for selecting a material having heat resistance, cold resistance, fatigue resistance, oil resistance, and high elastic limit properties as a material for a constant velocity joint boot. The wear resistance need not be taken into consideration. According to this material selection method, the material selection of the constant velocity joint boot having the above-described configurations of the present invention can be performed accurately.

  The constant velocity joint boot according to the present invention has a boot shape and wall thickness set based on the high elastic limit characteristics, so it is lightweight and compact, and the amount of encapsulated grease is reduced and the rotational expansion amount is reduced. It is suitable for high-speed rotation.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 and 2 show a first embodiment. As shown in FIG. 1A, the constant velocity joint boot 1 includes a large diameter cylindrical portion 2 attached to the end of the outer ring A of the constant velocity joint, and a boot fitting portion of the shaft B of the equal joint. A small-diameter cylindrical portion 3 to be attached and a cylindrical film-like portion 4 that integrally connects both the cylindrical portions 2 and 3. The cylindrical portions 2 and 3 are attached by engaging the annular protrusions 2a and 3a on the inner periphery with the boot mounting grooves D1 and D2 formed on the end of the outer ring A and the outer periphery of the boot fitting portion of the shaft B. These are fixed by annular fastening members Cl and C2.
In addition, when the shape of the end part of the outer ring A is a non-cylindrical shape, the large diameter cylindrical part 2 may form a shape according to the shape, or may form a cylindrical shape and the end part of the outer ring A Other members may be interposed in the gap.
When the shape of the large-diameter cylindrical portion 2 conforms to the end shape of the outer ring A, the inner surface may be along the end shape of the outer ring A, and the outer surface may be cylindrical. Both the outer surfaces may have a non-cylindrical shape conforming to the end shape of the outer ring A.
In the present invention, it is expressed as a “large-diameter cylindrical portion” including the above-described shape. FIG. 13 shows an example of the non-cylindrical shape described above. This is an example used for a tripod type constant velocity joint, but it is not limited to this shape.

  The constant velocity joint to which the boot 1 is attached is such that the outer diameter of the boot fitting portion of the shaft B is 0.2 to 0.4 times the outer diameter of the end portion of the outer ring A and does not take an operating angle. The distance between the end portion of the outer ring A and the boot fitting portion of the shaft B is 0.3 to 0.9 times the outer diameter of the end portion of the outer ring A, and the shaft B does not slide in the axial direction. Of the type.

  This constant velocity joint boot 1 is formed entirely or at least with a film-like portion 4 of an elastic material having a high elastic limit characteristic, and has a shape and thickness set based on the high elastic limit characteristic. is there. The constant velocity joint boot 1 has a simple cross-sectional shape having no irregularities such as a bellows shape based on a high elastic limit characteristic. In this embodiment, the film-like portion 4 includes both cylindrical portions. It is formed in a truncated cone shape that linearly connects two and three mutually facing ends.

The high elastic limit characteristic referred to here is a characteristic in which the modulus up to a large extension has a positive first-order gradient in the strain-stress curve. The above-mentioned “at the time of large extension” is, for example, at the time of extension of 160% or more, and more preferably 250% or more, in numerical terms.
When the high elastic limit characteristic is specified in relation to the configuration of the constant velocity joint boot 1, even if the boot 1 made of the material is flatter than the bellows shape, that is, it has a large number of peaks and valleys. Even if it is not a bent shape, it is a characteristic that has a high elastic limit to the extent that it can be a boot that can follow the behavior of the constant velocity joint 1.

  FIG. 1B shows a state when the constant velocity joint has the maximum operating angle. Even in this state, the film-like portion 4 bends outward on the side where the cylindrical portions 2 and 3 are close to each other and deforms so as to extend on the side where the cylindrical portions 2 and 3 are apart from each other. It can be followed. In other words, in a state where the constant velocity joint takes the maximum operating angle, the membrane portion 4 and the shaft B do not interfere with each other, and the boot 1 itself does not contact each other at any two locations. Here, the higher the elastic limit of the membrane-like part 4 is, the larger the operating angle of the constant velocity joint can be followed. When the dimensions of the constant velocity joint are in the above-described range, for example, if the film-like portion 4 is formed of a material having an elastic limit of 160% or more, the constant velocity joint also takes a large operating angle of 45 degrees or more. Can follow.

  If the shape and thickness of the boot 1 are set on the basis of the high elastic limit characteristics as in this configuration, the boot 1 may come into contact with other parts because it does not have to have the bellows shape of the conventional boot. Disappear. Therefore, wear due to contact does not occur. Therefore, even if the wear resistance of the material is reduced, the boot 1 can be used practically. Since the requirement for wear resistance is relaxed, the selection range of materials is expanded, and accordingly, the selection range of materials having high elastic limit properties is expanded.

  When deciding the shape and thickness of the boot 1, select it considering (1) heat resistance, (2) cold resistance, (3) fatigue resistance, and (4) oil resistance. In the embodiment, (5) selection is made by adding high elastic limit characteristics. The selection of wear resistance, which has been conventionally required, becomes unnecessary.

  FIG. 13 shows an example of a material selection method for the boot 1. This selection method includes a step of selecting heat resistance (S1), a step of selecting cold resistance (S2), a step of selecting fatigue resistance (S3), a step of selecting oil resistance (S4), Selecting a high elastic limit property (S5). The order of the steps (S1) to (S5) may be interchanged with each other, may be performed simultaneously, or any one or a plurality of steps (S1) to (S5) may be repeated.

  In addition to the above materials, the properties required for the material of the boot 1 include tensile breaking strength. The tensile strength at break is 3 to 40 MPa, preferably 5 to 30 MPa. Furthermore, it is preferable that the compression set when the material is compressed by 100 × 72 h × 10% is 80% or less. The material of the boot 1 provided with these materials is a thermoplastic elastomer, and is preferably any one of polyester, polyurethane, and polyamide. The boot 1 is formed of these materials by injection molding, compression molding, or blow molding, or a combination of injection, compression, and blow. The boot 1 may be formed of a plurality of materials in a layered manner, such as a laminating method.

  2 to 6 show modifications in which a part of the first embodiment described above with reference to FIG. 1 is modified. In the examples of FIGS. 2 to 6 and each of the examples in FIG.

  FIG. 2 shows a modification in which the thickness of the boot 1 is changed depending on the part. FIG. 2A is an example in which the large-diameter cylindrical portion 2 side is thickened, and the rotational expansion amount can be reduced by increasing the rigidity of the large-diameter cylindrical portion 2 side. On the other hand, FIG. 2B is an example in which the small-diameter cylindrical portion 3 side is thickened, and the flexibility on the relatively large-diameter cylindrical portion 2 side is relatively improved, so that the deformation of the membrane-like portion 4 during rotation is smoothly performed. Will come to be.

  FIGS. 3A, 3B and 3C are examples in which annular ribs 5 extending in the circumferential direction are provided on the outer surface, the inner surface or both the inner and outer surfaces of the membrane-like portion 4 in the vicinity of the large-diameter cylindrical portion 2, respectively. . In each of these examples, the rigidity of the portion where the annular rib 5 is provided increases, and the deflection deformation of the film-like portion 4 shown in FIG. 1B becomes more stable when the operating angle is taken. Also, the amount of rotational expansion can be reduced.

  4 (a), 4 (b), and 4 (c) are examples in which a plurality of annular ribs 5 similar to those shown in FIG. 3 are provided on the outer surface, the inner surface, or both the inner and outer surfaces of the film-like portion 4, respectively. The bending deformation of the film-like portion 4 when the corner is taken is further stabilized, and the rotational expansion amount is further reduced.

  5 (a) and 5 (b) are examples in which a plurality of linear ribs 6 extending along the axial direction are provided on the outer surface or the inner surface of the film-like portion 4, respectively, and FIGS. 6 (a) and 6 (b) respectively. This is an example in which linear ribs 7 wider than the ribs 6 in FIG. 5 are continuously provided in the circumferential direction on the outer surface or inner surface of the film-like portion 4. In addition, although illustration is abbreviate | omitted, a linear rib can also be provided in the inner and outer surfaces of a film-like part. By providing the linear ribs 6 and 7, it is possible to increase the overall rigidity of the film-like portion 4 and to suppress irregular deformation due to a deflection force acting during rotation.

  1 to 6 described above can be applied in combination of some of them. In addition, the boots of these examples stabilize the deflection deformation of the film-like portion 4 when the working angle is taken by attaching the boot to the equal arrest joint in the state where the working force is not applied in the state where the tensile force is applied in advance. be able to.

  7 to 9 show still other embodiments of the present invention. In these embodiments, the cross-sectional shape of the film-like portion 4 is assumed to have only one peak and no valley. By forming the film-like part 4 in such a shape, it is possible to stabilize the deformation of the film-like part 4 when the operating angle is taken.

  FIG. 7A shows an example in which a crest is provided in the vicinity of the large-diameter cylindrical portion 2 of the membrane-like portion 4, and FIG. 7B shows a modified example in which the crest is slightly enlarged. FIG. 7 (c) is an example in which the crest of the film-like portion 4 is gently formed from the large-diameter cylindrical portion 2 side to the small-diameter cylindrical portion 3 side, and the shape of this crest portion is changed to a constant velocity joint with a thin shaft diameter. FIG. 7D shows an example applied to the boot 1 to be attached.

  FIG. 8A shows a reduction in the rotational expansion amount by increasing the rigidity by increasing the thickness of the large-diameter cylindrical portion 2 with respect to the example shown in FIG. It is also possible to further stabilize the bending deformation (see FIG. 8B) of the film-like portion 4 in the stagnation state. It should be noted that other wall thickness distributions and rib formation described in the embodiments of FIGS. 2 to 6 can be applied to this example and each example of FIG.

  FIG. 9 shows the stabilization of the flexural deformation by forming a small waveform on the whole film-like part 4 and uniformly increasing the rigidity of the film-like part 4 with respect to the example of FIG. 7B. This is intended to reduce the amount of rotational expansion. It should be noted that such a small waveform formation on the entire film-like portion 4 can also be applied to the other examples of FIG. 7 and the examples of FIGS.

  FIG. 10 shows yet another embodiment. In this embodiment, the boot 1 attached to a slide type constant velocity joint in which the shaft B slides in the axial direction is designed to be the most compact. Here, the operating angle of the slide type constant velocity joint is generally set smaller than that of the fixed type, but the boot 1 needs to be able to elastically deform following the slide of the shaft B. is there. In the example shown in the figure, it is desirable that the film-like portion 4 is made of a material having a high elastic limit characteristic so that the slide amount of the shaft B is 20 mm or more and an angle of 15 deg or more can be obtained.

  FIG. 11 shows still another embodiment. In this embodiment, the cross-sectional shape of the film-like portion 4 is such that only one trough is provided at the center and peaks are provided on both sides thereof. By forming the film-like portion 4 in such a shape, the rigidity is increased, the deflection deformation can be stabilized, and the rotational expansion amount can be reduced. Here, when the diameter of the trough is 90% or more of the diameter of the crest on the small diameter side, the stress concentration in the trough can be sufficiently relaxed, and the crests are less likely to contact each other when the operating angle is taken.

  FIG. 12 shows still another embodiment. In this embodiment, as shown in FIG. 12 (a), the cross-sectional shape of the film-like portion 4 is narrowed at the central portion, that is, only one gentle valley portion is provided at the central portion. . Thereby, compared with each example of FIG. 1 thru | or FIG. 6, the internal volume of the boot 1 becomes small, the amount of grease in the boot 1 reduces, and reduction of rotational expansion amount can be aimed at.

  12 (b) to 12 (d) are modifications of FIG. 12 (a). Among these, FIG. 12 (b) shows that the vicinity of the large-diameter cylindrical portion 2 of the film-like portion 4 is thickened to stabilize the deflection deformation, and further, the vicinity of the small-diameter cylindrical portion 3 is thickened to increase the rotational expansion amount. This is a reduction.

  FIG. 12C shows an example in which an annular rib 5 is provided on the outer surface of the inflection point of the membrane-like portion 4, and FIG. 12D shows a spiral rib 8 provided on the outer surface of the membrane-like portion 4 on the small diameter cylindrical portion 3 side. In each of the examples, the rigidity of the film-like portion 4 is increased, the deflection deformation is stabilized, and the rotational expansion amount is reduced. These ribs 5 and 8 can also be provided on the inner surface or both inner and outer surfaces of the film-like portion 4. Further, a plurality of the annular ribs 5 may be provided as described in the embodiment of FIG. 4, and the spiral rib 8 may be provided on the large-diameter cylindrical portion 2 side. Further, various ribs may be used in combination, and the spiral rib 8 can be applied to each example shown in FIGS.

  In any of the above-described boots according to the embodiments, the shape of the film-like portion 4 is simple, and the length when the cross-sectional shape is extended linearly is the length between the opposite ends of both cylindrical portions. The length of the connecting straight line is 1.8 times or less (approximately 1.0 times in the first embodiment). As a result, the boot can be reliably made compact and light, and the amount of rotational expansion can be reduced, making it suitable for high-speed rotation. In addition, since there is little possibility that the membrane portions 4 and the membrane portion 4 and the shaft B are in contact with each other, the membrane portion 4 is hardly worn and the boot life can be extended.

(A) is a longitudinal cross-sectional view of the boot for constant velocity joints of 1st Embodiment, (b) is a longitudinal cross-sectional view which shows an example of the use condition of the boot of the same figure (a). (A), (b) is a longitudinal cross-sectional view which shows the modification of the boot of FIG. 1, respectively. (A)-(c) is a longitudinal cross-sectional view of another modification of the boot of FIG. 1, respectively. (A)-(c) is a longitudinal cross-sectional view of another modification of the boot of FIG. 1, respectively. (A), (b) is the side view seen from the shaft side of another modification of the boot of FIG. 1, respectively. (A), (b) is the side view seen from the shaft side of another modification of the boot of FIG. 1, respectively. (A) is the longitudinal cross-sectional view of the boot of other embodiment, (b)-(d) is a longitudinal cross-sectional view of the modification of the figure (a). (A) is a longitudinal cross-sectional view of the modified example of the boot of FIG.7 (d), (b) is a longitudinal cross-sectional view which shows an example of the use condition of the boot of the same figure (a). It is a longitudinal cross-sectional view which shows the modification of the boot of FIG.7 (b). It is a longitudinal cross-sectional view of the boot of other embodiment. It is a longitudinal cross-sectional view of the boot of other embodiment. (A) The longitudinal cross-sectional view of the boot of other embodiment, (b)-(d) is a longitudinal cross-sectional view of the modification of the figure (a), respectively. (A), (b) is the side view seen from the outer ring | wheel side of the example of a shape in case the large diameter cylindrical part 2 of the boot of FIG. 1 comprises a non-cylindrical shape, respectively. It is a flowchart which shows a material selection method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Boot 2 ... Large diameter cylindrical part 3 ... Small diameter cylindrical part 4 ... Membrane-like part

Claims (6)

  A constant-velocity joint boot that uses a material with high elastic limit properties, and whose shape and thickness are set based on the high elastic limit properties.   A large-diameter cylindrical portion attached to the outer ring end portion of the constant velocity joint, a small-diameter cylindrical portion attached to the boot fitting portion of the shaft of the constant velocity joint, and a membrane-like portion that integrally connects the two cylindrical portions. In a fast joint boot, a material having a high elastic limit property is used for the membrane-like portion, and the shape and thickness of the membrane-like portion are set based on the high elastic limit property. boots.   The constant velocity joint boot according to claim 1 or 2, wherein the high elastic limit characteristic has a characteristic in which a modulus up to an elongation state of 160% or more in the strain-stress curve has a positive primary gradient.   A large-diameter cylindrical portion attached to the outer ring end portion of the constant velocity joint, a small-diameter cylindrical portion attached to the boot fitting portion of the shaft of the constant velocity joint, and a membrane-like portion that integrally connects the two cylindrical portions. In a fast joint boot, a material having a high elastic limit property is used for the membrane-like portion, and the membrane-like portion and the shaft do not interfere with each other in a state where the constant velocity joint takes a maximum operating angle or the boot itself is arbitrary. A constant velocity joint boot characterized by having a shape in which mutual contact does not occur at the two locations.   5. The constant velocity joint boot according to claim 4, wherein the material of the film-like portion is a material that does not have the wear resistance required by the occurrence of the interference or contact.   A constant velocity joint boot comprising a step for selecting heat resistance, a step for selecting cold resistance, a step for selecting fatigue resistance, a step for selecting oil resistance, and a step for selecting high elastic limit characteristics. Material selection method.

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