JP2006250363A - Joint boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a joint boot capable of being axially positioned without impairing its mountability on an outer case and improving sealability, with respect to the joint boot mounted on the outer case having a non-circular outer peripheral shape. <P>SOLUTION: This joint boot 10 comprises a boot body 18 composed of a large diameter side mounting part 12, a small diameter side mounting part 14, and a bellows part 16, and a bush 20 interposed between the outer case and the large diameter side mounting part. An inner peripheral face of the bush has a fitted inner peripheral part 50 capable of being fixedly fitted onto the outer case, and an enlarged inner peripheral part 52 guiding the bush when it is externally fitted to the outer case, is formed at the end part on the opposite side of the bellows part in the form of a straight hole with a diameter larger than that of the outer case. A projection 56 fitted to a groove 54 of the outer case, is formed on the inner peripheral surface of the bush at a position out of an externally fitted area Q by the large diameter side mounting part between the fitted inner peripheral part 50 and the enlarged inner peripheral part 52. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a bellows-shaped joint boot mainly used for a constant velocity joint of an automobile.

  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. 18 and 19, 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. 19, 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. In order to enable attachment to such a non-circular outer case 6, 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. 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 such points, and in a joint boot attached to an outer case having a non-circular outer peripheral shape, positioning in the axial direction is possible without impairing the mounting property to the outer case. And it aims at improving the adhesiveness of the bush with respect to an outer case, and improving sealing performance.

  The joint boot according to the present invention includes a cylindrical large-diameter side attachment portion attached to the outer peripheral outer case side having a plurality of recesses in the circumferential direction, a cylindrical small-diameter side attachment portion attached to the shaft, and both A boot body composed of a bellows part that is integrally connected, and an outer peripheral surface that is interposed between the outer case and the large-diameter side attachment part and is fitted into the large-diameter side attachment part has a circular cross-section, And a bush provided with a plurality of convex portions that are fitted in the concave portion in a circumferential direction on an inner peripheral portion that is fitted and fixed to the outer case. The bush is provided with a close inner peripheral portion over the entire inner peripheral surface so that the bush can be tightly fitted to the outer case, and one end portion of the bush opposite to the bellows portion. Further, an enlarged inner peripheral portion that guides the outer case when the bush is externally fitted to the outer case is provided over the entire circumference of the inner peripheral surface. . Furthermore, the inner peripheral surface of the bush is provided with a protrusion that fits into a groove extending in the circumferential direction provided on the outer peripheral surface of the outer case, and the protrusion is formed between the contact inner peripheral portion and the expanded inner peripheral surface. In the axial direction of the bush, and is provided at a position away from the outer fitting region by the large-diameter side attachment portion on the side opposite to the bellows portion.

  According to the said structure, the protrusion provided in the inner peripheral surface of the bush fits in the groove | channel provided in the outer peripheral surface of an outer case, and the positioning in the axial direction of the joint boot with respect to an outer case is made. 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.

  Moreover, according to the said structure, the adhesiveness of the bush with respect to an outer case can be improved with the contact | adherence inner peripheral part provided in the inner peripheral surface of the bush. By providing the enlarged inner peripheral portion together with the tight inner peripheral portion, it is possible to easily fit the bush into the outer case while the bush can be tightly fitted onto the outer case. In addition, since the protrusion is disposed between the contact inner peripheral portion and the enlarged inner peripheral portion, the enlarged inner peripheral portion is terminated so as not to reach the outer fitting region by the large-diameter side attaching portion, Therefore, the tip of the outer case can be smoothly introduced from the enlarged inner peripheral portion to the tight inner peripheral portion through the protrusion.

  In the joint boot of the present invention, a sealing protrusion that extends in the circumferential direction may be provided over the entire circumference of the inner peripheral surface of the contact inner peripheral portion, thereby further improving the sealing performance with respect to the outer case. it can.

  In the joint boot of the present invention, the bush may include a tongue-like piece projecting in the axial direction on an end surface of the arcuate wall portion positioned between the convex portions adjacent in the circumferential direction. By providing such a tongue-shaped piece, excess molding material and air in the molding die can be released to this portion at the time of injection molding of the bush, and lack of the bush main body can be prevented. More specifically, the bush is an injection-molded body formed by injecting a molding material from the center in the circumferential direction of the convex portion, and the tongue-shaped piece is formed in the center in the circumferential direction of each arc-shaped wall portion. It is preferable to be provided. Thereby, the moldability of a convex part can be improved further.

  In the joint boot of the present invention, the large-diameter side mounting portion includes a fixing concave portion extending in a circumferential direction for receiving a tightening member on an outer peripheral surface, and the fixing concave portion surrounds the outer periphery of the distal end portion of the outer case. It may be connected to the bellows part via a cylindrical connection part, and the cylindrical connection part may be formed in a constricted shape recessed radially inward at the axially central part. By making the cylindrical connecting portion into a constricted cylindrical shape in this way, when bent and deformed at a wide angle, the valley portion on the large-diameter side mounting portion side of the bellows portion is on the distal end surface of the outer case when bent and deformed. Contact can be avoided and durability can be improved. In this case, it is preferable that the cylindrical connecting portion is formed in a constricted shape radially inward, whereby the cylindrical connecting portion can be appropriately bent at the time of bending deformation.

  In the joint boot of the present invention, the small-diameter side mounting portion includes a fixing recess extending in the circumferential direction for receiving the fastening member on the outer peripheral surface, and one extending in the circumferential direction provided on the outer peripheral surface of the shaft. Two sealing protrusions that fit together in the groove are provided on the inner peripheral surface side of the fixing recess, and the two sealing protrusions are disposed adjacent to each other in the axial direction, and both sealing protrusions are provided. The space may be connected via a curved valley. Thereby, the sealing performance with respect to the shaft of a small diameter side attaching part can be improved.

  In the joint boot of the present invention, the bellows portion is composed of two mountain groups, a mountain group near the large-diameter side attachment portion and a mountain group near the small-diameter side attachment portion, and in the mountain group near the large-diameter side attachment portion. The unfolded length in the axial direction of each mountain may be set to be larger than the unfolded length in the axial direction of each mountain in the mountain group near the small-diameter side attachment portion. Here, the unfolded length in the axial direction of each mountain is the length along the slope of the mountain from the valley bottom on one side to the valley bottom on the other side of each mountain. By increasing the development length of each mountain in the mountain group near the large-diameter side mounting portion in this way, when bending and deforming at a wide angle, it is easy to deform in the mountain group near the large-diameter side mounting portion, Durability can be improved. From such a viewpoint, in the mountain group near the large-diameter side attachment portion, the height of each mountain is larger than the width of each mountain, and in the mountain group near the small-diameter side attachment portion, the height of each mountain Is preferably set smaller than the width of each mountain.

  According to the present invention, it is possible to position the joint boot in the axial direction with respect to the outer case without impairing the mounting property to the outer case, and to improve the adhesiveness of the bush to the outer case, thereby providing excellent sealing performance. Obtainable.

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

  FIG. 1 is a sectional view of a joint boot 10 according to the embodiment, and FIG. 2 is an exploded view thereof. The joint boot 10 is attached to a triport type constant velocity joint for an automobile as shown in FIGS.

  As shown in FIG. 15, the constant velocity joint is provided at the end of a triport 4 in which three trunnions 3 each 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 injected using a thermoplastic elastomer resin such as TPO or rubber such as chloroprene rubber as a molding material. Molded by molding. Thereby, the adhesiveness of the bush 20 with respect to the outer case 6 can be improved while improving the durability of the bellows portion 16.

  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. 3 and 4, the bush 20 has an outer peripheral surface on which the large-diameter side mounting portion 12 is externally fitted, has a circular cross section, and an inner peripheral portion that is externally fitted and fixed to the outer case 6. A plurality of convex portions 26 to be fitted 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. 3 and 4, 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 inward in the radial direction 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 have two pairs of bottomed first lightening holes 38A, 40A, 40A, 38A (see FIG. 3). , The other end face 20B side, and two pairs of bottomed second hollow holes 38B, 40B, 40B, 38B (see FIG. 4) 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). Moreover, the 3rd support wall 37 extended in the circumferential direction which supports the inner wall part 30 is comprised by the wall part which divides between the said 1st meat hole and the 2nd wall hole (refer FIG. 6), ie, 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. 5, 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.

  As shown in FIG. 8, the large-diameter mounting portion 12 of the boot body 18 is provided with a sealing protrusion 42 on the inner peripheral surface side of the fixing recess 22. The sealing protrusion 42 has a gentle mountain shape and is formed over the entire circumference in the circumferential direction. Further, on the outer peripheral surface side of the large-diameter side attachment portion 12, a concave groove 43 for blow-molding the sealing protrusion 42 is provided on the bottom surface of the fixing concave portion 22.

  On the other hand, the outer peripheral portion of the bush 20 is provided with a shallow rectangular annular groove 44 into which the sealing protrusion 42 is fitted, and receives the end surface 12A of the large-diameter side attachment portion 12 in the axial direction. A possible enlarged portion 46 is formed at the end. 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 T 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 T 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 sealing inner peripheral portion 50 is provided with two sealing protrusions 51, 51 over the entire periphery. As shown in FIG. 8, the sealing protrusion 51 is arranged on the outer circumferential surface of the annular groove 44 on the outer side in the axial direction and close to the axial direction. As a result, when the fastening member 7 is tightened as shown in FIG. 9, a tightening force can be effectively exerted on the sealing protrusion 51 from the shoulder 44 </ b> A of the annular groove 44 where the highest pressure acts. High sealing performance can be obtained. Further, as shown in FIG. 6, the sealing protrusion 51 is arranged on the convex portion 26 so as to overlap both end portions in the axial direction of the third support wall 37, whereby the tightening by the tightening member 7 is performed. The force is effectively transmitted to the sealing protrusion 51 via the third support wall 37, and high sealing performance is obtained.

  Further, the bush 20 has a straight hole shape larger in diameter than the outer case 6 at one end opposite to the bellows portion 16, and guides the outer case 6 when the bush 20 is externally fitted to the outer case 6. An expanded 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. As a whole, the radius is larger than the radius at the corresponding portion of the outer case 6, for example, as shown in FIG. 14, the radius D1 at the convex portion 26 is set larger than the 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 Q by the large diameter side attaching 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. 8 and 14, 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.

  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 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 exist at three locations on the circumference as shown in FIG. As shown in FIG. 9, the protrusion 56 is disengaged in the axial direction of the bush 20 from the external fitting region Q by the large-diameter side mounting portion 12, that is, the region where the bush 20 and the large-diameter side mounting 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.

  As shown in FIGS. 4 and 10, the bush 20 has a tongue-like piece 58 projecting integrally from the end face of each arcuate wall 28 in the axial direction. The tongue piece 58 is provided in the circumferential center of each arcuate wall portion 28 on the bellows portion side end face 20B of the bush 20, and is formed in a tapered trapezoidal plate shape in plan view shown in FIG. . Moreover, as shown in FIG. 9, the tongue-like piece 58 protrudes inclining radially inward toward the tip.

  As shown in FIG. 11, a molding die 60 for injection molding the bush 20 includes a first die 61 for molding the anti-bellows portion side end surface 20A of the bush 20, a second die 62 for molding the outer peripheral surface, It consists of the 3rd type | mold 63 which shape | molds a surrounding surface. An injection port 64 is provided so as to inject a molding material from the center in the circumferential direction of each convex portion 26 on the bellows portion side end surface 20B (see FIG. 4), and each end surface 20B on the same side as the injection port 64 is provided. A cavity 65 for forming the tongue-like piece 58 is provided at the center in the circumferential direction of the arc-shaped wall portion 28. Thereby, at the time of injection molding, excess molding material and air in the mold 60 can be released into the cavity 65, and lack of the bush body can be prevented. In particular, since the injection port 64 is provided in each convex portion 26, the cavity 65 is provided in the arcuate wall portion 28 therebetween, and both are provided on the same end face 20B side, the flow of the molding material is improved, The lack of thickness is eliminated, and the moldability of the convex portion 26 having the above-described structure of the hollow holes is excellent. Note that the tongue piece 58 itself may have a lack of thickness. As shown by a chain line 58A in FIG. 8, the tongue-like piece 58 is formed so as to protrude parallel to the axial direction during injection molding, but has a shape inclined inward due to contraction after injection molding. In addition, by inclining inward in this way, coupled with the tapered trapezoidal shape, the bush 20 can be easily inserted into the large-diameter side mounting portion 12 and the assembly workability is excellent.

  As shown in FIGS. 9 and 15, in the large-diameter side attachment portion 12 of the boot body 18, the fixing recess 22 is a bellows portion via a cylindrical connecting portion 66 that surrounds the outer periphery of the distal end portion 6 c of the outer case 6. 16 is connected. As shown in FIG. 7, the cylindrical connecting portion 66 has a short cylindrical shape extending in the axial direction with a constant thickness from the bellows side shoulder 22B of the fixing recess 22, and the bellows side end 66A is The bellows portion 16 is connected to a slope portion 16B constituting a first trough portion (a trough portion on the largest diameter side mounting portion 12 side) 16A.

  The cylindrical connecting portion 66 is formed in a constricted shape in which the central portion in the axial direction is curved inward in the radial direction. The constriction shape of the cylindrical connecting portion 66 should be clearly distinguished from the mountain-and-valley shape in the bellows portion 16, and is configured in detail as follows. First, the bottom 66B of the constriction on the outer peripheral surface of the cylindrical connecting portion 66 is within the range A1 between the bottom surface 22A of the fixing recess 22 and the tip 42A of the sealing protrusion 42 in the radial direction of the cylindrical connecting portion 66. Is located. More preferably, the bottom 66B of the constriction is located in a range A2 between the bottom surface 22A of the fixing recess 22 and the inner peripheral surface 12B of the large-diameter side attachment portion 12. Further, the bellows portion side end 66A on the outer peripheral surface of the cylindrical connecting portion 66 is changed from the bellows portion side shoulder portion 22B of the fixing concave portion 22 to the thickness Y of the cylindrical connecting portion 66 in the radial direction of the cylindrical connecting portion 66. The corresponding dimension is located in a range B1 between the radially outer position 68 and the inner peripheral surface 12B of the large-diameter mounting portion 12 in the fixing recess 22. More preferably, the bellows portion side end 66 </ b> A is located within a range B <b> 2 between the bellows portion side shoulder 22 </ b> B of the fixing recess 22 and the bottom surface 43 </ b> A of the concave groove 43. Further, in this embodiment, the bellows portion side end 66A of the cylindrical connecting portion 66 is located radially inward from the bellows portion side shoulder portion 22B of the fixing recess 22 that is the end on the anti-bellows portion side. Is formed. By forming in such a range, the moderate flexibility of the cylindrical connection part 66 mentioned later can be ensured, and the unwanted buckling of the cylindrical connection part 66 can be avoided.

  As shown in FIG. 12, the small-diameter mounting portion 14 is provided with two sealing protrusions 70 on the inner peripheral surface side of the fixing recess 24 over the entire circumference. The two sealing ridges 70 are adjacent to each other in the axial direction with a gentle cross-sectional shape, and the two are connected via a valley 72 having a curved shape (circular arc). Yes. As shown in FIG. 13, the two sealing protrusions 70 are fitted together in one circumferential groove 74 provided on the outer circumferential surface of the shaft 1, The width W1 in the axial direction of the two sealing protrusions 70 is set to be larger than the opening width W2 of the groove 74 so that the slopes on the outer sides of both protrusions 70 abut the opening edges 74A, 74A. The depth of the valley portion 72 is such that the valley bottom is located between a height H corresponding to the opening width W2 of the groove 74 and a height I corresponding to the inner peripheral surface 14A of the small-diameter side attachment portion 14. (See FIG. 12). A notch 73 is provided on the shoulder portion of the fixing recess 24 on the bellows side.

  As shown in FIG. 1, the bellows portion 16 includes five hills including a first hill 76A, a second hill 76B, a third hill 76C, a fourth hill 76D, and a fifth hill 76E in this order from the large-diameter side mounting portion 12 side. It consists of These are composed of two mountain groups that are distinguished by the cross-sectional shape, that is, a mountain group 78 near the large-diameter side mounting portion composed of a first mountain 76A and a second mountain 76B, a third mountain 76C, a fourth mountain 76D, and It is comprised with the mountain group 80 near the small diameter side attaching part which consists of the 5th peak 76E. And the expansion | deployment length E in the axial direction of each mountain is set so that all of the mountain group 78 near the large-diameter side attachment portion is larger than the mountain group 80 near the small-diameter side attachment portion. Here, the expansion length E is the length along the slope of the mountain from the valley bottom 82A on one side to the valley bottom 82B on the other side, as shown in an enlarged manner in FIG.

  Further, as shown in FIG. 1, in the mountain group 78 near the large-diameter side attachment portion, the heights F1 and F2 of each mountain are set larger than the widths G1 and G2 of each mountain (F1> G1, F2> G2). On the other hand, in the mountain group 80 near the small-diameter mounting portion, the heights F3, F4, and F5 of each mountain are set smaller than the widths G3, G4, and G5 of each mountain. Here, the mountain heights F1 to F5 are distances in the direction perpendicular to the axis from the valley bottom on the small-diameter side mounting portion 14 side of each mountain to the peak of the mountain, and the mountain widths G1 to G5 are It is the distance in the axial direction between the valley bottoms on both sides.

  When the joint boot 10 constructed as described above is attached to a constant velocity joint, as shown in FIGS. 14 and 15, 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.

  Here, when the bush 20 is externally fitted to the outer case 6, the outer case 6 is easily fitted by being guided by the enlarged diameter inner peripheral portion 52 of the bush 20. Further, at this time, the arc-shaped wall portion 28 of the bush 20 is provided with the projection 56 on the inner peripheral surface, but the outer fitting region in which the outer peripheral surface is constrained by the large-diameter side mounting portion 12 with the high hardness. Since it is not provided in Q, 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 outside the outer fitting region Q together with the enlarged diameter inner peripheral portion 52, the distal end portion 6 c of the outer case 6 is moved from the enlarged inner peripheral portion 52 to the contact inner peripheral portion 50 through the protrusion 56. It can be introduced smoothly. 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.

  Then, when the bush 20 is mounted on the outer case 6 in this manner, the projection 56 is fitted into the groove 54 of the outer case 6 as shown in FIG. 9, and the bush 20 is positioned in the axial direction. The Moreover, the high sealing performance between the bush 20 and the outer case 6 is ensured by the close contact inner peripheral part 50 and the sealing protrusion 51 provided there.

  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 providing the bush 20 with the enlarged diameter portion 46 having a long axial dimension X, when the boot body 18 is assembled to the bush 20 with a robot hand or artificially assembled, the large diameter side of the boot body 18 is provided. The problem that the mounting portion 12 pushes over the diameter-expanded portion 46 and gets over it can be prevented, and the assemblability is excellent. 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. Therefore, the surface pressure exerted on the outer case 6 by the inner wall portion 30 can be made as uniform as possible in the circumferential direction, and the sealing performance can be improved.

  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. While ensuring, the deformation | transformation of the core by an injection pressure can be suppressed, and a moldability can be improved. 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 that is nearly perpendicular to the inner wall portion 30. The pressure can be made more uniform in the circumferential direction, and the sealing performance at the convex portion 26 can be improved.

  In particular, according to the present embodiment, the cylindrical connecting portion 66 in the large-diameter side mounting portion 12 of the boot body 18 is formed in a constricted shape as described above, so that it is bent when being bent and deformed at a wide angle. On the inner side, it is possible to avoid the first valley portion 16 </ b> A on the large-diameter side attachment portion 12 side of the bellows portion 16 from contacting the front end surface 6 d of the outer case 6.

  FIG. 16 is a cross-sectional view showing the joint boot 10 according to the above-described embodiment in a state where the joint boot 10 is bent and deformed by tilting the shaft 1 at a wide angle, and FIG. It is sectional drawing which shows the state which deform | transformed similarly the joint boot 200 of the comparative example which is straight rather than. As shown in the drawing, in the comparative example, the first valley portion 206 on the large diameter side mounting portion 204 side of the bellows portion 202 is pressed against the distal end surface 6d of the outer case 6 by the second valley portion 208 in the bent inner side. There is a possibility that the durability is impaired due to this. On the other hand, in the embodiment, it is avoided that the first valley portion 16A of the bellows portion 16 contacts the front end surface 6d of the outer case 6 on the inner side of the bend, which is clear from the case of the comparative example shown in FIG. Had different deformation shapes. In the present embodiment, when the joint boot 10 is bent and deformed, the constricted cylindrical connecting portion 66 acts like a hinge having the axial center portion as a hinge center, and the bellows portion side end 66A is outside. This is due to bending deformation so as to warp, and thereby, the deformation of the inclined surface portion 16B of the bellows portion 16 approaching the front end surface 6d of the outer case 6 is suppressed.

  Further, according to the present embodiment, in the small-diameter side mounting portion 14, the two sealing protrusions 70 are fitted into the groove 74 of the shaft 1 as shown in FIG. The This is because the two sealing protrusions 70 are fitted in the narrow groove 74, so that the repulsive force that the two inwardly compressed crests return to the outside works, and the pressure at the opening edge 74A is reduced. This is thought to be due to the increase. Moreover, since the troughs 72 between the protrusions 70 are curved as described above, the repulsive force is increased and a higher sealing performance can be obtained. Furthermore, in this embodiment, since the notch 73 is provided in the bellows side shoulder of the fixing recess 24, the joint boot is easily bent and deformed in the J direction (see FIG. 13). Therefore, the force of the sealing protrusion 70 on the bellows portion side to rise from the shaft 1 is reduced, and the sealing performance can be improved.

  Further, according to the present embodiment, in the bellows portion 16, the development length E of each mountain of the mountain group 78 near the large-diameter side attachment portion is increased, and the heights F1 to F5 and widths G1 to G5 of each mountain are increased. Is set as described above, and when it is bent and deformed at a wide angle, the mountain group 78 near the large-diameter side mounting portion on which a large stretching force acts can be easily stretched and deformed, thereby improving durability. it can. In particular, an inboard constant velocity joint may be bent and deformed at a wide angle while being extended in the axial direction. In this case as well, the mountain group 78 near the large-diameter side mounting portion can be easily expanded and contracted. And durability can be improved. In the above embodiment, the five bellows portions are used. However, the number of the mountain portions is not limited to this, and may be, for example, six. In that case, the mountain group near the large-diameter side attachment portion and the small-diameter side attachment portion. It is preferable that there are three mountain groups on each side.

  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 Exploded sectional view of the joint boot FIG. 2 side view in the III direction IV side view of Fig. 2 Cross section of convex part of bush Sectional view taken along line VI-VI in FIG. Enlarged cross-sectional view of the large-diameter side mounting part of the joint boot Exploded sectional view showing the mounting configuration of the large diameter side mounting part to the outer case Sectional drawing which shows the attachment state to the outer case of a large-diameter side attachment part Bush main part enlarged plan view Cross-sectional view of a mold for molding a bush Exploded sectional view showing the mounting structure of the small diameter side mounting part to the shaft Sectional view showing the mounting state of the small diameter side mounting part to the shaft Sectional drawing which shows the state in the middle of assembling a joint boot to a constant velocity joint Sectional view showing the joint boot assembled to the constant velocity joint Sectional drawing which shows the state which bent and deformed the joint boot which concerns on embodiment Sectional drawing which shows the state which bent and deformed the joint boot which concerns on a comparative example 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, 6c ... Tip part, 7 ... Fastening member, 8 ... Fastening member, 10 ... Joint boot, 12 ... Large diameter side attaching part, 14 ... Small diameter side attaching part, 16 DESCRIPTION OF SYMBOLS ... Bellows part, 18 ... Boot body, 20 ... Bush, 22 ... Fixing recessed part, 24 ... Fixing recessed part, 26 ... Convex part, 28 ... Arc-shaped wall part, 50 ... Adhering inner peripheral part, 51 ... Sealing protrusion , 52 ... Expanded inner peripheral part, 54 ... Outer case groove, 56 ... Projection, 58 ... Tongue piece, 66 ... Cylindrical connecting part, 70 ... Sealing protrusion, 72 ... Valley part, 74 ... Shaft groove 78 ... Mountain group near the large-diameter side mounting part, 80 ... Mountain group near the small-diameter side mounting part, E ... Development length in the axial direction of each mountain, F1 to F5 ... Height of each mountain, G1 to G5 ... Each Width of mountain, Q ... external fitting area

Claims (9)

From a cylindrical large-diameter side mounting part attached to the outer peripheral outer case side having a plurality of recesses in the circumferential direction, a cylindrical small-diameter side mounting part attached to the shaft, and a bellows part integrally connecting the two The boot body and
An outer peripheral surface that is interposed between the outer case and the large-diameter side mounting portion and that fits in the large-diameter side mounting portion has a circular cross section, and an inner peripheral portion that is externally fixed to the outer case. A plurality of protrusions fitted into the recesses provided with a bush distributed in the circumferential direction,
The bush is provided with a close inner peripheral portion over the entire inner peripheral surface so that the bush can be tightly fitted to the outer case, and one end portion of the bush opposite to the bellows portion. In addition, a straight hole having a diameter larger than that of the outer case, and an enlarged inner peripheral portion that guides the outer case when the bush is externally fitted to the outer case is provided over the entire inner peripheral surface. A protrusion is provided on the inner peripheral surface of the bush to fit in a circumferentially extending groove provided on the outer peripheral surface of the outer case, and the protrusion includes the contact inner peripheral portion and the enlarged inner peripheral portion. And a joint boot that is provided at a position that is disengaged from the outer fitting region by the large-diameter side attachment portion on the opposite side to the bellows portion in the axial direction of the bush.   The joint boot according to claim 1, wherein a sealing protrusion extending in the circumferential direction is provided on the inner peripheral portion of the contact portion over the entire circumference of the inner peripheral surface.   2. The joint boot according to claim 1, wherein the bush includes a tongue-like piece projecting in an axial direction on an end surface of an arcuate wall portion positioned between the convex portions adjacent in the circumferential direction.   The bush is an injection-molded body formed by injecting a molding material from each circumferential center of the convex portion, and the tongue-like piece is provided at the circumferential center of each arcuate wall portion. The joint boot according to claim 3.   The large-diameter side mounting portion includes a fixing recess extending in the circumferential direction for receiving a tightening member on the outer peripheral surface, and the fixing recess surrounds the outer periphery of the distal end portion of the outer case via the cylindrical connecting portion. 2. The joint boot according to claim 1, wherein the joint boot is connected to the bellows part, and the cylindrical connection part is formed in a constricted shape recessed inward in the radial direction at an axially central part.   The joint boot according to claim 5, wherein the cylindrical connecting portion is formed in a constricted shape in a radially inward direction.   The small-diameter side mounting portion is provided with a fixing recess extending in the circumferential direction for receiving the fastening member on the outer peripheral surface, and is fitted together in one groove extending in the circumferential direction provided on the outer peripheral surface of the shaft. Two sealing ridges are provided on the inner peripheral surface side of the fixing recess, the two sealing ridges are disposed adjacent to each other in the axial direction, and the valley between the two sealing ridges is curved. The joint boot according to claim 1, wherein the joint boot is connected to the joint boot.   The bellows portion is composed of two mountain groups, a mountain group near the large-diameter side attachment portion and a mountain group near the small-diameter side attachment portion, and the axial development of each mountain in the mountain group near the large-diameter side attachment portion. The joint boot according to claim 1, wherein a length is set to be larger than a developed length in an axial direction of each mountain in the mountain group near the small-diameter side attachment portion.   In the mountain group near the large-diameter side mounting portion, the height of each mountain is larger than the width of each mountain, and in the mountain group near the small-diameter side mounting portion, the height of each mountain is The joint boot according to claim 8, wherein the joint boot is smaller than the width.

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