JP4181137B2 - Joint boots - Google Patents

Description

  The present invention relates to a bellows-shaped joint boot mainly used for an automobile triport type constant velocity joint or the like.

  A triport type joint is known as one of constant velocity joints used for vehicle drive shafts and the like.

  For example, as shown in FIGS. 9 and 10, the triport type constant velocity joint has three trunnions 3 having rollers 2 protruding in a direction perpendicular to the axis on one shaft 1 on the input side and the output side. And the outer case 6 provided at the end of the other shaft 5. The outer case 6 has three sliding grooves 6 a in the axial direction corresponding to the tripart 4 on the inner periphery thereof. The constant velocity joint is capable of transmitting rotational torque while allowing the shafts 1 and 5 to be angled by fitting the roller 2 of the triport 4 with the sliding groove 6a so as to be slidable in the axial direction. It is configured.

  In such a constant velocity joint, in order to prevent dust and foreign matter from entering the joint, or to keep the sealed grease, generally, the portion of the shaft 1 on the side of the triport 4 from the outer case 6 is used. A joint boot 100 having a bellows shape that can be appropriately expanded and contracted and bent so as to cover is mounted. The joint boot 100 is formed as a large-diameter side attachment portion 101 having one end portion in the axial direction fitted on the outer periphery of the outer case 6 and fixed by a fastening member 7 such as a ring-shaped band, and the other end portion is the tripart 4. It is formed as a small-diameter side mounting portion 102 that is fixed to the outer periphery of the side shaft 1 by a fastening member 8 such as a ring-shaped band, and the both 101 and 102 are integrally connected by a bellows portion 103.

As shown in FIG. 10, the outer case 6 is provided with three circumferentially arranged recesses 6b on the outer periphery corresponding to the arrangement of the inner peripheral sliding grooves 6a. The shape is formed in a non-circular shape having an uneven shape in the circumferential direction. A so-called two-piece type joint in which a separate bush 105 is interposed between the outer case 6 and the large-diameter side attachment portion 101 in order to enable attachment to such a non-circular outer case 6. Boots are known (see Patent Document 1). The bush 105 has a circular outer peripheral surface, and a plurality of convex portions 104 projecting radially inward corresponding to the concave portions 6b of the outer case 6 are dispersed in the inner peripheral portion in the circumferential direction. Is provided.
US Pat. No. 5,529,538

  In the joint boot disclosed in Patent Document 1, a groove is provided on the outer peripheral surface of the outer case, while a protrusion that fits into the groove is provided on the inner peripheral surface of the bush. It is presumed that the joint boot is positioned in the axial direction with respect to. In the same document, the protrusion is provided in an outer fitting region by the large-diameter side mounting portion in the axial direction of the bush.

  However, with the structure in which the protrusion is provided in the outer fitting region by the large-diameter side mounting portion, when the joint boot is to be attached to the outer case with the large-diameter side mounting portion being fitted to the bush, the outer periphery of the bush Since the surface is constrained by the large-diameter side mounting portion, there is a problem that it is difficult to spread outward, and thus it is difficult to mount. In particular, when the boot body is formed of a material having a hardness higher than that of the bush in order to improve the durability of the bellows portion, the outer periphery of the bush is constrained by the large-diameter side mounting portion having a high rigidity. Difficult to spread and wearability is impaired.

  The present invention has been made in view of these points, and in a joint boot that is attached to a non-circular outer peripheral case, positioning in the axial direction is possible without impairing attachment to the outer case. The purpose is to.

The joint boot according to the present invention includes a large-diameter side attaching portion attached to the outer case side of the outer peripheral shape having a plurality of recesses in the circumferential direction, a small-diameter side attaching portion attached to the shaft, and a bellows portion integrally connecting the two. And an outer peripheral surface on which the large-diameter side mounting portion is externally fitted has a circular cross section and is external to the outer case. And a bush provided with a plurality of convex portions that are fitted in the concave portion and distributed in the circumferential direction on the inner peripheral portion to be fitted and fixed. And the protrusion which fits into the groove | channel extended in the circumferential direction provided in the outer peripheral surface of the said outer case is provided in the inner peripheral surface of the said bush, and this protrusion is the said large diameter side attaching part in the axial direction of the said bush. Is provided at a position deviated from the outer fitting region . In the convex portion, the bush has an inner wall portion projecting radially inward, an arc-shaped outer wall portion constituting a part of the outer peripheral surface of the bush, and the inner wall portion and the outer wall portion. And a left and right side support wall connecting the inner wall portion and the outer wall portion on both sides of the central support wall, thereby forming the convex portion. 4 are formed side by side in the circumferential direction, and the lightening holes are opened on one end face side of the bush and are arranged on the other end face side. A third support wall extending in the circumferential direction that supports the inner wall portion by a wall portion that divides the first and second lightening holes from each other. Is provided. And the thickness of the said 3rd support wall is the thickness of the 1st center support wall and the side support wall which partition the said 1st hollow hole, and the 2nd center support which partitions the said 2nd hollow hole It is set to be thicker than both the wall and side support walls and the inner wall.

In this case, the protrusions provided on the inner peripheral surface of the bush are fitted into the grooves provided on the outer peripheral surface of the outer case, whereby the joint boot is positioned in the axial direction with respect to the outer case. In addition, since the projection is provided outside the outer fitting region by the large-diameter side mounting portion, the projection portion can spread without being constrained by the large-diameter side mounting portion when mounted on the outer case. Easy to insert the outer case into the bush. Therefore, positioning in the axial direction can be performed without impairing the mounting property to the outer case.
In addition, since the inner wall portion of the convex portion is supported by three support walls, that is, a central support wall and side support walls on both sides thereof, for example, tightening with a tightening member from the outside of the large-diameter side attachment portion When fixed, variations in tightening force can be most effectively reduced. That is, when the three support walls are arranged at equal intervals in the circumferential direction, while supporting the central portion of the inner wall portion having the largest radial inward extension with the central support wall, The side support walls can be arranged so that the tightening force is uniform on both sides as much as possible. In addition, if the three support walls are used, the mold shape may be relatively simple, and the core for forming the hollow hole can also ensure a certain cross-sectional area, so that the injection pressure Can be prevented from being deformed. Therefore, it is possible to reduce the variation in the tightening force and to ensure the surface pressure exerted by the inner wall portion on the outer case as much as possible in the circumferential direction as much as possible while ensuring the moldability, and to improve the sealing performance.
Further, the thickness of the third support wall is the thickness of the first support wall that partitions the first cutout holes, the thickness of the second support wall that partitions the second cutout holes, and the inner side Since it is set to be thicker than any of the wall thickness, the tightening force by the tightening member can be reliably transmitted to the inner wall portion.

  This positioning protrusion may be provided at a position deviating from the bellows part side with respect to the external fitting region by the large-diameter side attaching part, or may be provided at a position deviating from the bellows part.

  When the projection is provided at a position away from the bellows portion with respect to the outer fitting region, the shaft of the large-diameter side attachment portion of the boot body is compared with the case where the projection is provided at a position off the bellows portion side. There is an advantage that the direction length can be shortened. That is, when the protrusion is provided on the bellows portion side of the outer fitting region, it is necessary to secure an axial length for forming the protrusion on the bellows portion side, and accordingly, the shaft in the large-diameter side attachment portion of the boot body. Although the directional dimension may become long, when it is provided at a position away from the bellows part, it does not affect the axial dimension of the large-diameter side attachment part.

  In this case, an enlarged diameter portion capable of receiving the end surface of the large diameter side attachment portion in the axial direction is formed on the outer peripheral portion of the bush, and the protrusion is provided on the inner peripheral surface of the bush in the enlarged diameter portion. Is preferred. By providing such an enlarged diameter part, the assembly property of the boot main body with respect to a bush can be improved. Further, since the protrusion is provided on the inner peripheral surface of the enlarged diameter portion, the axial dimension of the bush is not increased only for positioning. In particular, when the axial dimension of the enlarged diameter portion is made longer in consideration of the assembling property, a sufficient axial dimension for providing the protrusion on the inner periphery of the enlarged diameter portion is secured, which is preferable.

  Further, in this case, the bush is provided with an inner peripheral portion having a smaller diameter than the outer case over the entire circumference of the inner peripheral surface, and the bush is configured so as to be closely fitted and fitted to the outer case. An enlarged inner peripheral portion that guides the outer case when the bush is fitted to the outer case in a straight hole shape having a diameter larger than that of the outer case, at one end of the bush opposite to the portion. It is preferable that the protrusion is provided over the entire circumference of the inner peripheral surface, and the protrusion is provided between the contact inner peripheral portion and the enlarged inner peripheral portion. By providing such a close inner peripheral portion, the close contact of the bush with the outer case can be improved. In addition, by providing the above-mentioned enlarged diameter inner peripheral portion, the bush can be easily fitted on the outer case while the bush can be tightly fitted on the outer case. Further, since the protrusion provided on the inner peripheral surface of the enlarged diameter portion is disposed between the tight inner peripheral portion and the enlarged inner peripheral portion, the enlarged inner peripheral portion reaches the outer fitting region by the large-diameter side attachment portion. Since it terminates so as not to reach, the tip of the outer case can be smoothly guided from the enlarged inner peripheral portion to the tight inner peripheral portion through the protrusion.

  On the other hand, in the case where the protrusion is provided at a position deviated to the bellows part side with respect to the outer fitting region by the large diameter side attachment part, the fixing recess extending in the circumferential direction for the large diameter side attachment part to receive the tightening member is An inner peripheral portion on the bellows portion side with respect to the fixing concave portion surrounds the outer peripheral surface of the bush with a gap, and the inside of the bush is within an axial range surrounded by the gap. It is preferable that the protrusion is provided on the peripheral surface. In this case, at the time of mounting on the outer case, the protruding portion is allowed to spread outward by the gap, and mounting properties can be ensured.

  In the joint boot of the present invention, the protrusion does not need to be provided on the entire circumference of the inner peripheral surface of the bush, and is preferably provided only on the arcuate wall portion positioned between the convex portions adjacent in the circumferential direction. As a result, it is excellent in mountability to the outer case.

  In the joint boot of the present invention, when the bush is made of a material softer than the boot main body, the adhesion of the bush to the outer case can be improved while improving the durability of the bellows part.

  In the joint boot, when the side support wall is inclined so as to approach the center support wall toward the outer side, it is possible to ensure the demoldability of the core for forming the lightening hole. In addition, the side support wall that supports the outer surface of the inner wall portion can be coupled at an angle close to perpendicular to the inner wall portion, and the surface pressure exerted on the outer case by the inner wall portion is made more uniform in the circumferential direction. be able to.

  According to the present invention, in a joint boot attached to a non-circular outer shape outer case like a triport type constant velocity joint, the axial direction of the joint boot with respect to the outer case without impairing the mounting property to the outer case Positioning can be performed.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a joint boot 10 according to an embodiment. The joint boot 10 is attached to a triport type constant velocity joint for automobiles as shown in FIGS. .

  As shown in FIG. 7, the constant velocity joint is provided at the end of a triport 4 in which three trunnions 3 having a roller 2 on an input side shaft 1 project in a direction perpendicular to the axis, and an output side shaft 5. The outer case 6 is provided. The outer case 6 has three sliding grooves 6a in the axial direction corresponding to the tripart 4 on the inner periphery thereof, and three equal parts in the circumferential direction on the outer peripheral portion corresponding to the arrangement of the sliding grooves 6a. The recessed part 6b arrange | positioned is provided, and the outer periphery shape of the outer case 6 is formed in the non-circular shape which makes uneven | corrugated shape in the circumferential direction by this.

  The joint boot 10 includes a boot body 18 including a large-diameter side attachment portion 12 attached to the outer case 6 side, a small-diameter side attachment portion 14 attached to the shaft 1, and a bellows portion 16 integrally connecting the two, and an outer This is an assembly of the bush 20 interposed between the case 6 and the large-diameter side attachment portion 12.

  For example, the boot body 18 is formed by blow molding using a thermoplastic elastomer resin such as TPEE or TPO. On the other hand, the bush 20 is molded separately using a material softer than the boot body 18. For example, the bush 20 is formed by injection molding using a thermoplastic elastomer resin such as TPO or a rubber material such as chloroprene rubber. Molded. In this case, it is preferable that the hardness of the boot body 18 is set to 40 to 50 degrees in JISD hardness, and the hardness of the bush 20 is set to 55 to 85 degrees in JISA hardness (based on JISK6253). When the hardness of the bush 20 is less than 55 degrees as the JISA hardness, the bushing 20 becomes too soft and the sealing performance is deteriorated, and when it exceeds 85 degrees, it becomes too hard and the fastening performance may be lowered. Moreover, if the hardness of the boot body 18 is less than 40 degrees in terms of JISD hardness, the rigidity decreases and the bellows portion 16 is likely to be deformed by an impact force, and if it exceeds 50 degrees, the boot body 18 becomes too hard and durability may be reduced. is there.

  The large-diameter side mounting portion 12 of the boot body 18 has a short cylindrical shape having a circular cross section on the inner and outer peripheral surfaces, and a fixing recess 22 for receiving the ring-shaped fastening member 7 is formed on the outer peripheral surface. Is provided. The small-diameter side mounting portion 14 has a short cylindrical shape that is fitted and fixed to the shaft 1 on the triport 4 side, and a fixing concave portion 24 that extends in the circumferential direction for receiving the ring-shaped fastening member 8 on the outer peripheral surface. Is provided. The large-diameter side attachment portion 12 and the small-diameter side attachment portion 14 are arranged coaxially, that is, with a common axis O. The bellows portion 16 is a tapered bellows body formed so as to be sequentially reduced from the large-diameter side attachment portion 12 to the small-diameter side attachment portion 14, and the hollow portion serves as a grease-filled space 25.

  As shown in FIGS. 2 and 3, the bush 20 has an outer peripheral surface on which the large-diameter mounting portion 12 is externally fitted and has a circular cross section, and the concave portion 6 b is formed on the inner peripheral portion that is externally fixed to the outer case 6. A plurality of convex portions 26 that are fitted to each other are distributed in the circumferential direction. The convex portions 26 protrude toward the inner side in the radial direction, and are uniformly arranged every 120 degrees in the circumferential direction. Specifically, the convex portion 26 is formed in a mountain shape having a gentle cross-sectional shape, and is set to a symmetrical shape with respect to the center line L in the circumferential direction when viewed in the axial direction of the bush 20. It is smoothly connected to the arcuate wall portion 28 therebetween.

  As shown in FIGS. 2 and 3, the convex portion 26 has an arc shape that forms a part of the outer peripheral surface of the bush 20 and an inner wall portion 30 that protrudes radially inward and fits into the concave portion 6 b. Center support walls 34A, 34B for connecting the wall portions 30, 32 at the center in the circumferential direction to the hollow portion between the inner wall portion 30 and the outer wall portion 32, On the left and right sides, a pair of left and right side support walls 36A, 36A; 36B, 36B for connecting both wall portions 30, 32 are provided. As a result, the convex portion 26 is provided with four hollow holes recessed in the axial direction side by side in the circumferential direction. Specifically, the lightening holes are opened to the one end face 20A side of the bush 20 and are symmetric with respect to the center line L, and two bottomed first lightening holes 38A, 40A, 40A, 38A (see FIG. 2) , The other end face 20B side, and two pairs of bottomed second hollow holes 38B, 40B, 40B, 38B (see FIG. 3) that are symmetrical with respect to the center line L. A first support wall (center support wall 34A and side support walls 36A, 36A) that partitions the first cutout holes and a second support wall (center support wall 34B and side supports) that partition the second cutout holes. Wall 36B, 36B). Further, a third support wall 37 extending in the circumferential direction for supporting the inner wall portion 30 is provided by a wall portion that partitions the first and second hollow holes (see FIG. 1). The first and second cutout holes are provided on both sides of the support wall 37 on the axial center side of the bush 20. Note that the depths of the four first cutout holes 38A, 40A, 40A, 38A are the same. Also, the four second hollow holes 38B, 40B, 40B, 38B have the same depth, and the depth is slightly shallower than the first hollow holes 38A, 40A.

  As shown in FIG. 4, the first central support wall 34 </ b> A is a radially extending wall portion that supports the inner wall portion 30 with respect to the outer wall portion 32, and the inner wall portion 30 projects inwardly. It is provided at the center in the largest circumferential direction. The first side support wall 36A is a wall portion that supports the inner wall portion 30 with respect to the outer wall portion 32, and is not parallel to the central support wall 34A provided radially from the axis O but is inclined. Is provided. The side support wall 36A has a base portion 30A to the outer wall portion of the inner wall portion 30 such that the inner wall portion 30 is supported by the central support wall 34A and the side support walls 36A, 36A at equal intervals in the circumferential direction. The inner wall portion 30 is supported at an intermediate position between the connecting portion 30B and the central support wall, that is, connected to the inner wall portion 30 at the intermediate position. Further, the connecting portion is provided so as to cross the inner wall portion 30 substantially perpendicularly so as to be inclined toward the center, that is, toward the central support wall 34A as it goes outward from the connecting portion. Here, it is preferable that the coupling angle θ of the side support wall 36A with respect to the inner wall portion 30 is substantially vertical. Specifically, the coupling angle θ is within a range of 70 ° to 110 ° (that is, 90 ° ± 20 °). It is preferable that it exists, More preferably, it exists in the range of 80 degrees-100 degrees. This coupling angle θ is an angle formed by the center line N of the side support wall 36A and the tangent line P on the inner peripheral surface of the inner wall portion 30 intersecting the center line N. By providing the first support walls 34A and 36A in this way, the pair of first first hollow holes 40A and 40A near the center line L have a trapezoidal cross-sectional shape in which the outer peripheral surface side of the bush 20 is narrowed, The pair of outer first hollow holes 38A, 38A have a triangular cross section.

  The structure of the second central support wall 34B and the side support walls 36B, 36B is the same as the structure of the first central support wall 34A and the side support walls 36A, 36A described above. The structures of 40B, 40B, and 38B are also the same as the first cutout holes 38A, 40A, 40A, and 38A, and the positions and shapes are the same.

  Then, the thickness T2 of the first support walls 34A, 36A, the thickness T5 of the second support walls 34B, 36B, the thickness T1 of the inner wall 30 of the convex portion 26, and the convex adjacent to each other in the circumferential direction. The thickness T4 of the arc-shaped wall portion 28 located between the portions 26 is set to be the same or substantially the same in order to make the cooling rate of the resin material or the rubber material in each wall portion uniform. On the other hand, the thickness T3 in the axial direction of the third support wall 37 is set to be thicker than these thicknesses T1, T2, T4, and T5. Thereby, the tightening force by the tightening member 7 can be reliably transmitted to the inner wall portion 30.

  As shown in FIGS. 1 and 5, an annular convex portion 42 is projected on the inner peripheral portion of the large-diameter side mounting portion 12 of the boot body 18, and the annular convex portion 42 is fitted on the outer peripheral portion of the bush 20. A shallow annular groove 44 is provided.

  In addition, an enlarged diameter portion 46 that can receive the end surface 12A of the large-diameter side attachment portion 12 in the axial direction is formed on the outer peripheral portion of the bush 20. The enlarged diameter portion 46 has a length X in the axial direction so that the larger diameter side attachment portion 12 does not push down the enlarged diameter portion 46 as the bush 20 and the larger diameter side attachment portion 12 are fitted. It is set to be longer than the wall thickness Z of the large-diameter side mounting portion 12, thereby increasing the rigidity of the enlarged-diameter portion 46 in the axial direction. Here, the length X of the enlarged diameter portion 46 is set longer than the thickness T4 of the arcuate wall portion 28, and the rigidity is further enhanced. In general, when the bush 20 is injection-molded, the length of the enlarged diameter portion is set to a dimension similar to the thickness of the adjacent wall portion in consideration of the flow of resin in the cavity. The example is characterized in that the rigidity is increased by making it longer than the wall thickness T4 of the adjacent arc-shaped wall portion 28. The length X of the enlarged diameter portion 46 is such a length that the large diameter side attachment portion 12 does not push down the enlarged diameter portion 46, and is 2 to 5 times the wall thickness Z of the large diameter side attachment portion 12. Preferably there is. Thereby, the rigidity of the enlarged diameter part 46 can be improved, suppressing the increase in manufacturing cost. The thickness Z of the large-diameter side attachment portion 12 is the maximum value of the thickness of the portion on the tip side of the fixing recess 22.

  As for the outer peripheral part of the bush 20, the one end part 48 by the side of the bellows part 16 is formed in a tapered shape having a smaller diameter toward the tip. Thereby, when fitting the large diameter side attaching part 12 to the bush 20, the large diameter side attaching part 12 can be guided by this tapered part 48, and the assembling property of both can be improved.

  The bush 20 is provided with a contact inner peripheral portion 50 having a smaller diameter than the outer case 6 over the entire inner peripheral surface. That is, the contact inner peripheral portion 50 is set so that the contour of the inner peripheral surface is smaller than the contour of the outer peripheral surface of the outer case 6. Since the protrusions 26 that fit into the recesses 6b of the outer case 6 are distributed on the inner periphery of the bush 20 as described above, the radius varies in the circumferential direction. For this reason, the radius of the inner peripheral surface of the contact inner peripheral portion 50 is set to be smaller than the radius at the corresponding portion of the outer case 6 in the entire circumferential direction. For example, as shown in FIG. The radius D2 is set smaller than the radius D0 of the outer case 6 in the recess 6b. As a result, the bush 20 is configured to be tightly fitted to the outer case 6.

  Further, the diameter of the bush 20 on the side opposite to the bellows portion 16 is larger than that of the outer case 6 in one end, and the diameter of the outer case 6 is increased when the bush 20 is fitted on the outer case 6. An inner peripheral portion 52 is provided over the entire inner peripheral surface. The inner peripheral surface 52 of the enlarged diameter inner diameter is set to be larger than the contour of the outer peripheral surface of the outer case 6, that is, the radius of the inner peripheral surface of the enlarged inner peripheral portion 52 is set in the circumferential direction. For example, as shown in FIG. 6, a radius D1 at the convex portion 26 is set to be larger than a radius D0 of the outer case 6 at the concave portion 6b. The enlarged diameter inner peripheral portion 52 is terminated so as not to reach the outer fitting region by the large diameter side attachment portion 12 in the axial direction of the bush 20. That is, the enlarged diameter inner peripheral portion 52 is provided within the range of the axial length X of the enlarged diameter portion 46 from the one end face 20 </ b> A of the bush 20, that is, formed with an axial dimension shorter than the enlarged diameter portion 46. Has been. The boundary between the enlarged inner peripheral portion 52 and the contact inner peripheral portion 50 is a tapered hole, and the boundary between the enlarged inner peripheral portion 52 and the one end face 20A of the bush 20 is also a tapered hole.

  As shown in FIGS. 5 and 6, a groove 54 extending in the circumferential direction is provided on the outer peripheral surface of the outer case 6. The groove 54 is provided only on the circumference corresponding to the sliding groove 6a of the outer case 6, and is not provided on the circumference corresponding to the recess 6b.

  As shown in FIGS. 5 and 7, a protrusion 56 that fits into the groove 54 is provided on the inner peripheral surface of the bush 20. The protrusions 56 are formed so as to extend in the circumferential direction only in the arc-shaped wall portion 28 between the convex portions 26 so as to correspond to the grooves 54, and are present at three locations on the circumference as shown in FIGS. To do. Further, the protrusion 56 is located in a position outside the external fitting region Q by the large-diameter side attachment portion 12 in the axial direction of the bush 20, that is, from the region where the bush 20 and the large-diameter side attachment portion 12 are fitted, In this example, it is installed at a position away from the bellows portion 16 with respect to the external fitting region Q. Specifically, the protrusion 56 is an inner peripheral surface of the bush 20 in the enlarged diameter portion 46, and is provided between the contact inner peripheral portion 50 and the enlarged inner peripheral portion 52. One side thereof is a close contact inner peripheral portion 50, and the other side is an enlarged diameter inner peripheral portion 52.

  When the joint boot 10 constructed as described above is attached to the constant velocity joint, as shown in FIGS. 6 and 7, the large-diameter side attachment portion 12 of the boot body 18 is fitted and fixed to the bush 20, and then the bush 20 is attached to the outer case 6. And the small-diameter side mounting portion 14 is externally fitted to the shaft 1 and the fastening members 7 and 8 are fastened and fixed to the fixing recesses 22 and 24, respectively.

  When the bush 20 is externally fitted to the outer case 6, the outer case 6 is guided by the enlarged inner peripheral portion 52 of the bush 20, so that the bush 20 can be easily externally fitted to the outer case 6. At this time, the arc-shaped wall portion 28 of the bush 20 is provided with a protrusion 56 on the inner peripheral surface. The protrusion 56 is formed in the outer fitting region Q in which the outer peripheral surface is constrained by the large-diameter side mounting portion 12 having high hardness. Since it is not provided, the bush 20 tends to spread radially outward at the protrusion 56 portion, and therefore the outer case 6 can be easily inserted into the bush 20. Further, at this time, since the protrusion 56 is located outside the outer fitting region Q together with the enlarged diameter inner peripheral portion 52, the tip of the outer case 6 is smoothly passed from the enlarged inner peripheral portion 52 to the contact inner peripheral portion 50 through the protrusion 56. Can be introduced. Further, even in the circumferential direction portion of the convex portion 26 where the protrusion 56 is not provided, the enlarged diameter inner peripheral portion 52 is provided in a range that does not reach the outer fitting region Q, and thus is guided by the enlarged diameter inner peripheral portion 52. When pushing the outer case 6 into the tight inner periphery 50, it is not necessary to apply an excessive force from the beginning, and the outer case 6 can be introduced smoothly. That is, when the enlarged diameter inner peripheral portion 52 extends to the outer fitting region Q, an excessive force is required from the beginning when the outer case 6 is pushed into the tight inner peripheral portion 50. Such a problem is solved. When the bush 20 is attached to the outer case 6 in this way, the projection 56 is fitted into the groove 54 of the outer case 6 and the bush 20 is positioned in the axial direction. Further, the tight inner peripheral portion 50 ensures a high sealing performance between the bush 20 and the outer case 6. From the above, it is possible to position the bush 20 in the axial direction without impairing the mounting property to the outer case 6 and to ensure high sealing performance.

  Further, by increasing the axial dimension X of the enlarged diameter portion 46, when the boot body 18 is assembled to the bush 20 with a robot hand or when artificially assembled, the large-diameter side mounting portion 12 of the boot body 18 is It is possible to prevent a problem that the enlarged diameter portion 46 is pushed down and gets over. Moreover, since the axial dimension X of the enlarged diameter portion 46 is long, a sufficient axial dimension for providing the projection 56 on the inner periphery thereof can be ensured.

  Further, since the inner wall portion 30 of the convex portion 26 is supported by the three support walls of the central support walls 34A and 34B in the center in the circumferential direction and the side support walls 36A and 36A; 36B and 36B on both sides thereof. Side support walls 36A, 36A; 36B so that the central portion of the inner wall portion 30 with the largest radial inward extension is supported by the central support walls 34A, 34B, and the tightening force is made uniform on both sides as much as possible. , 36B can be provided, and variations in tightening force can be effectively reduced.

  In addition, as described above, the side support walls 36A and 36B are inclined so as to approach the center support walls 34A and 34B toward the outer side, so that the following operational effects can be obtained. That is, when the side support walls 36A and 36B are arranged in parallel to the central support walls 34A and 34B, the cross-sectional areas of the outer side holes 38A and 38B on the outer side of the side support walls 36A and 36B are reduced. It is difficult to remove the core for molding, but by inclining as described above, the cross-sectional area of the outer hollow holes 38A and 38B can be increased, and the core can be removed from the mold. The moldability can be improved by securing. Further, the side support walls 36 </ b> A and 36 </ b> B that support the outer side surface of the inner wall portion 30 can be coupled to the inner wall portion 30 at an angle close to vertical, and therefore, the surface that the inner wall portion 30 exerts on the outer case 6. The pressure can be made more uniform in the circumferential direction, and the sealing performance at the convex portion 26 can be improved.

  FIG. 8 shows an example of changing the arrangement position of the projection 56. In this example, the protrusion 56 is provided at a position away from the bellows portion 16 side with respect to the outer fitting region Q by the large-diameter side attachment portion 12. On the bellows portion 16 side of the external fitting region Q, the large-diameter side mounting portion 12 exists on the outer periphery of the bush 20, so that the large-diameter side mounting portion is not constrained by the large-diameter side mounting portion 12. 12, a portion closer to the bellows portion 16 than the fixing recess 22 projects outward in the radial direction, and the inner peripheral portion of the projecting portion 60 surrounds the outer peripheral surface of the bush 20 with a gap 58 therebetween. A protrusion 56 is provided on the inner peripheral surface of the bush 20 within an axial range surrounded by the gap 58. Further, the groove 54 of the outer case 6 is also provided closer to the distal end side of the outer case 6 than the case of the above-described embodiment so as to be fitted to the protrusion 56. Since other configurations are the same as those in the above embodiment, the description thereof is omitted.

  Even in the example shown in FIG. 7, the same functions and effects as those of the above embodiment are basically obtained. In this case, the protrusion 56 of the bush 20 spreads outward by the gap 58 when the outer case 6 is mounted. Is allowed, so that the wearability can be ensured.

  As described above, the joint boot of the present invention enables positioning in the axial direction without impairing the mounting property to the outer case, and as a joint boot mainly used for an automobile triport type constant velocity joint or the like. It can be suitably used.

The longitudinal cross-sectional view of the joint boot which concerns on embodiment of this invention A view of the bush of the joint boot viewed from the outside of one end face View of the bush viewed from the outside of the other end face Enlarged cross-sectional view of the projection on one end of the bush The principal part expanded sectional view in the state where the joint boot was attached to the constant velocity joint Sectional drawing which shows the state in the middle of assembling the joint boot to a constant velocity joint Sectional drawing which shows the state which attached the joint boot to the constant velocity joint The principal part expanded sectional view in the state where the joint boot concerning other embodiments was attached to the constant velocity joint. Sectional drawing which shows the state which assembled the conventional joint boot to the constant velocity joint It is a side view of an equivalent speed joint.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Shaft, 6 ... Outer case, 6b ... Recessed part, 7 ... Tightening member, 10 ... Joint boot, 12 ... Large diameter side attaching part, 14 ... Small diameter side attaching part, 16 ... Bellows part, 18 ... Boot body, 20 ... Bush, 22 ... Concave for fixing, 26 ... Convex, 28 ... Arc wall, 30 ... Inner wall, 32 ... Outer wall, 34A, 34B ... Center support wall, 36A, 36B ... Side support wall, 38A , 40A ... first hollow hole, 38B, 40B ... second hollow hole, 46 ... enlarged diameter portion, 48 ... tapered portion, 50 ... tight inner peripheral portion, 52 ... enlarged inner peripheral portion, 54 ... groove, 56 ... protrusions, 58 ... gap

Claims (9)

A boot main body comprising a large-diameter side attaching portion attached to the outer case side of the outer peripheral shape having a plurality of recesses in the circumferential direction, a small-diameter side attaching portion attached to the shaft, and a bellows portion integrally connecting both;
An outer peripheral surface that is interposed between the outer case and the large-diameter side mounting portion, and an outer peripheral surface on which the large-diameter side mounting portion is externally fitted has a circular cross-sectional shape and is externally fixed to the outer case. A plurality of convex portions that fit into the concave portions are provided dispersed in the circumferential direction, and
A protrusion that fits in a circumferentially extending groove provided on the outer peripheral surface of the outer case is provided on the inner peripheral surface of the bush, and the protrusion is externally attached by the large-diameter side mounting portion in the axial direction of the bush. Ri Ah provided to the outside from the fitting area position,
In the convex portion, the bush has an inner wall portion projecting radially inward, an arc-shaped outer wall portion constituting a part of the outer peripheral surface of the bush, and both the inner wall portion and the outer wall portion. A central support wall extending in the radial direction connected at the center in the circumferential direction, and left and right side support walls connecting the inner wall portion and the outer wall portion on both sides of the central support wall. Two hollow holes are provided side by side in the circumferential direction,
The said hollowing hole consists of four first hollowing holes opened on one end face side of the bush and arranged in the circumferential direction, and four second hollowing holes opened on the other end face side and arranged in the circumferential direction, A third support wall extending in the circumferential direction is provided to support the inner wall portion by a wall portion that partitions between the first hole and the second hole;
The thickness of the third support wall is the thickness of the first central support wall and the side support wall that partitions the first hollow holes, the second central support wall that partitions the second hollow holes, and A joint boot characterized in that it is set to be thicker than both the thickness of the side support wall and the thickness of the inner wall portion .   The joint boot according to claim 1, wherein the protrusion is provided at a position away from the bellows portion with respect to the outer fitting region.   The enlarged diameter part which can receive the end surface of the said large diameter side attaching part in an axial direction is formed in the outer peripheral part of the said bush, The said protrusion was provided in the internal peripheral surface of the bush in the said enlarged diameter part. Joint boots.   The bush is provided with a contact inner peripheral portion having a smaller diameter than the outer case over the entire circumference of the inner peripheral surface, and the bush is configured so as to be closely attached to the outer case, and opposite to the bellows portion. One end portion of the bush has a straight hole shape larger in diameter than the outer case, and an enlarged inner peripheral portion for guiding the outer case when the bush is externally fitted to the outer case has an entire inner peripheral surface. The joint boot according to claim 3, wherein the joint boot is provided over a circumference, and the protrusion is provided between the contact inner peripheral portion and the enlarged inner peripheral portion.   The joint boot according to claim 1, wherein the protrusion is provided at a position disengaged toward the bellows portion with respect to the outer fitting region.   The large-diameter side mounting portion includes a fixing recess extending in the circumferential direction for receiving the tightening member on the outer peripheral surface, and the inner peripheral portion on the bellows portion side of the fixing recess has a gap between the outer peripheral surface of the bush. The joint boot according to claim 5, wherein the protrusion is provided on an inner peripheral surface of the bush within an axial range surrounded by the gap.   The joint boot according to claim 1, wherein the protrusion is provided only on an arcuate wall portion positioned between the convex portions adjacent in the circumferential direction.   The joint boot according to claim 1, wherein the bush is made of a material softer than the boot body. Joint boot according to claim 1, characterized in that the side supporting walls are inclined so as to approach to the central support wall as outward.

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