Seal Structure

Abstract

To provide a sealing structure of a constant velocity joint that can be easily assembled to a propeller shaft while suppressing entry of foreign substances from outside.SOLUTION: A sealing structure 1 of a constant velocity joint 3 is equipped with a boot 10 covering an outer peripheral side of a propeller shaft 2. The boot 10 is equipped with a band fastening portion 15, a boot lip portion 20, an intermediate portion 25 that is formed in an intermediate part in an axial direction with respect to the band fastening portion 15 and the boot lip portion 20, and a ventilation portion 30 that communicates an inside with an outside of the constant velocity joint 3. The ventilation portion 30 is equipped with a band fastening portion side ventilation path 31 formed on the band fastening portion 15, an intermediate ventilation path 32 formed on the intermediate portion 25, and a boot lip portion side ventilation path 33 formed on the boot lip portion 20. The band fastening portion side ventilation path 15 and the boot lip portion side ventilation path 33 are arranged at different angles in a circumferential direction of the propeller shaft 2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a seal structure, and more particularly to a seal structure for a constant velocity joint used in a propeller shaft. [Background technology]

[0002] Conventionally, propeller shafts are used in various vehicles. The propeller shafts are used in FR (Front engine Rear drive) rear-wheel drive vehicles, full-time 4WD, part-time 4WD and other four-wheel drive vehicles, and the like. The propeller shaft is used, for example, to transmit driving force from an engine or the like at the front to rear drive wheels (rear wheels). Here, the propeller shaft is extended by connecting a plurality of shafts with constant velocity joints so that the shafts reach from the engine to the drive wheels. In addition, the constant velocity joint is intended to absorb relative movement between the shafts (for example, Patent Document 1).

[0003] The constant velocity joint is provided with a boot as a sealing member to prevent grease inside from leaking to the outside and to prevent foreign matter from entering from the outside. However, if the boot is made more airtight, there is a problem that the internal pressure inside the constant velocity joint increases when the constant velocity joint is assembled to the propeller shaft, creating resistance and making the assembly difficult.

[0004] Furthermore, the boot has a problem of being deformed by the increase in internal pressure of the constant velocity joint as the propeller shaft rotates. Therefore, the constant velocity joint described in the above Patent Document 1 is formed with an air passage that allows the expanded air inside the constant velocity joint to leak to the outside in order to suppress the increase in internal pressure of the constant velocity joint. The air passage is formed as an air groove on the inner wall of the fastening portion (corresponding to the mounting portion) of the tightening band of the boot. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Utility Model Application Publication No. 7-44969 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the constant velocity joint described in Patent Document 1 has an air passage that is linearly connected to the outside of the constant velocity joint, which causes problems such as grease inside the constant velocity joint leaking out and foreign matter (including water) being sucked into the constant velocity joint. As a result, there is a concern that the constant velocity joint described in Patent Document 1 will have a shortened lifespan. In addition, when a boot lip is used in the constant velocity joint described in Patent Document 1, there is a concern that the increase in internal pressure cannot be suppressed because the airtightness is increased by the interference of the boot lip.

[0007] Also, instead of the above, if an air vent were provided in the bottom of the joint cup, etc., there was a concern that grease would leak from the constant velocity joint. This would reduce the lifespan of the constant velocity joint and components adjacent to the constant velocity joint (such as dynamic dampers). Furthermore, if an air vent were formed in the propeller shaft, there was a concern that the strength of the propeller shaft would be reduced. Also, if the propeller shaft was thin, there was a concern that it would be difficult to process.

[0008] SUMMARY OF THE PRESENT EMBODIMENTS In view of the above, an object of the present invention is to provide a seal structure for a constant velocity joint that can be easily assembled to a propeller shaft while suppressing the intrusion of foreign matter from the outside. [Means for solving the problem]

[0009] (1) The seal structure of the present invention, which is provided to solve the above-mentioned problems, is a seal structure for a constant velocity joint used in a propeller shaft, and includes a boot covering an outer circumferential side of the propeller shaft, the boot including a band fastening portion that is fastened to the propeller shaft by being tightened from the outer circumferential side, a boot lip portion that is formed to extend along the axial direction of the propeller shaft and covers the outer circumferential side of the propeller shaft, an intermediate portion that is formed midway in the axial direction between the band fastening portion and the boot lip portion, and a seal structure for a constant velocity joint used in a propeller shaft, the seal structure including a band fastening portion that is fastened to the propeller shaft by being tightened from the outer circumferential side, a boot lip portion that is formed to extend along the axial direction of the propeller shaft and covers the outer circumferential side of the propeller shaft, and a ventilation section communicating the inside and the outside, the ventilation section comprising: a band fastening section side ventilation passage formed along the axial direction of the propeller shaft at the position where the band fastening section is provided, an intermediate section ventilation passage formed at the position where the intermediate section is provided, and a boot lip section side ventilation passage formed along the axial direction of the propeller shaft at the position where the boot lip section is provided, and the band fastening section side ventilation passage and the boot lip section side ventilation passage are arranged at different angles in the circumferential direction of the propeller shaft.

[0010] In the above-mentioned seal structure, the ventilation section is divided into three ventilation paths, namely, the band fastening portion side ventilation path, the intermediate portion ventilation path, and the boot lip side ventilation path, and each ventilation path is arranged so as not to be linear in one direction (for example, the ventilation paths are arranged in a labyrinth structure in which each ventilation path is arranged in a maze). That is, the above-mentioned seal structure can set the distance from the outer side to the inner side of the constant velocity joint long while ensuring the escape of air from the inner side of the constant velocity joint. Therefore, while suppressing an increase in pressure on the inner side of the constant velocity joint, it is possible to effectively suppress the intrusion of foreign matter (including water) from the outer side of the constant velocity joint. As a result, the above-mentioned seal structure can suppress an increase in internal pressure in the constant velocity joint when the constant velocity joint is assembled to a shaft such as a propeller shaft, thereby improving the workability during assembly. In addition, the above-mentioned seal structure can suppress the intrusion of foreign matter from the outer side of the constant velocity joint, thereby suppressing damage to the constant velocity joint and the propeller shaft.

[0011] Here, it is preferable that the band-fastening portion-side ventilation passage is formed with a diameter large enough to communicate with the outside of the constant velocity joint when the boot is fastened to the propeller shaft by the band, thereby ensuring ventilation through the band-fastening portion-side ventilation passage even when the boot is tightened by the band.

[0012] (2) In the seal structure of the present invention described above, the boot lip side ventilation passage has an inner opening end that opens toward the intermediate ventilation passage and an outer opening end that opens toward the outer side of the boot lip, and is characterized in that, in cross-sectional view, the diameter of the passage decreases from the inner opening end to the outer opening end.

[0013] The above-described seal structure, by being configured as described above, can effectively prevent foreign matter and the like from entering from the outside of the constant velocity joint, and can facilitate the escape of air from the inside of the constant velocity joint.

[0014] (3) The above-mentioned sealing structure of the present invention may be characterized in that an elastic member is provided at an outer opening end of the boot lip side air passage, the elastic member protruding from the outer opening end toward the outer side of the constant velocity joint, and in cross-sectional view, the elastic member is tapered in diameter as it moves from the outer opening end toward the outer side of the constant velocity joint.

[0015] By being configured in this manner, the above-mentioned sealing structure can more effectively prevent foreign matter and the like from entering from the outside of the constant velocity joint, and can more smoothly allow air to escape from the inside of the constant velocity joint.

[0016] (4) In the above-described seal structure of the present invention, it is preferable that the elastic member elastically deforms so that the opening end side expands in diameter when there is air passage from the inside to the outside of the constant velocity joint, and elastically deforms so that the diameter of the opening end side is maintained or reduced when there is no air passage from the inside to the outside of the constant velocity joint.

[0017] In the above-described seal structure, when there is air flow from the inside to the outside of the constant velocity joint, the open end side of the elastic member elastically deforms to expand in diameter, thereby effectively suppressing an increase in internal pressure of the constant velocity joint. That is, the above-described seal structure allows the elastic member to function as a one-way valve. This allows the above-described seal structure to improve workability when assembling the constant velocity joint. In addition, when there is no air flow from the inside to the outside of the constant velocity joint, the above-described seal structure elastically deforms to maintain or reduce the diameter of the open end side of the elastic member, thereby effectively suppressing the intrusion of foreign matter and the like from the outside of the constant velocity joint.

[0018] (5) In the above-described seal structure of the present invention, the elastic member may be formed so that the rigidity of the inner surface side at the base end side is higher than the rigidity of the tip end side.

[0019] The above-mentioned seal structure can reliably expand, maintain, or reduce the diameter of the open end of the elastic member according to the ventilation state of the constant velocity joint. As a result, the above-mentioned seal structure can suppress an increase in internal pressure in the constant velocity joint when the constant velocity joint is assembled to a shaft such as a propeller shaft, thereby improving the ease of assembly. In addition, the above-mentioned seal structure can suppress the intrusion of foreign matter from the outside of the constant velocity joint, thereby suppressing damage to the constant velocity joint and the propeller shaft.

[0020] (6) The sealing structure of the present invention described above may be characterized in that a circumferential groove is formed on the inner wall of the intermediate portion along the outer periphery of the propeller shaft, the circumferential groove communicating with the band fastening portion side air passage and the boot lip portion side air passage and elastically deforming the tip side of the boot lip portion in the inward radial direction starting from the circumferential groove.

[0021] By configuring the above-mentioned seal structure in this way, the circumferential groove functions as the intermediate ventilation passage. Moreover, since the circumferential groove is formed along the circumferential direction of the inner wall of the intermediate section, it is possible to prevent the intermediate ventilation passage from extending in the axial direction of the propeller shaft. Therefore, the above-mentioned seal structure is expected to reduce the size of the boot. Moreover, since the circumferential groove allows the tip side of the boot lip portion to elastically deform in the inner radial direction starting from the circumferential groove, it is possible to bring the tip side of the boot lip portion into contact with the propeller shaft. As a result, the above-mentioned seal structure can effectively prevent foreign matter and the like from entering the inside of the constant velocity joint from the tip side of the boot lip portion, and can prevent grease from leaking from the inside of the constant velocity joint to the outside. Effect of the Invention

[0022] The present invention can provide a seal structure for a constant velocity joint that can be easily assembled to a propeller shaft while suppressing the intrusion of foreign matter from the outside. [Brief description of the drawings]

[0023] [Figure 1] 1 is a partially cutaway overall view of a propeller shaft and a constant velocity joint to which a seal structure according to an embodiment of the present invention is applied. [Diagram 2] 1 is a cross-sectional view of a seal structure according to an embodiment of the present invention. [Diagram 3] FIG. 2A is a schematic cross-sectional view of a seal structure according to the present invention, and FIG. 2B is a view taken in the direction of the arrow AA in FIG. [Figure 4] FIG. 2A is a schematic cross-sectional view of an elastic member and a boot lip side air passage constituting the seal structure of the present invention, and FIG. 2B is a cross-sectional view taken along the line CC. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] An embodiment of a seal structure 1 according to the present invention will be described in detail below with reference to Figs. 1 to 4. In this embodiment, an example will be described in which the seal structure 1 is applied to a constant velocity joint 3 used in a propeller shaft 2. Note that the sizes in the drawings may differ from the actual sizes. Also, note that a transfer case, drive wheels, and the like connected to the propeller shaft 2 are omitted in Fig. 1. Also, note that an elastic member 34 is omitted in Figs. 2 and 3(a).

[0025] As shown in Fig. 1, the propeller shaft 2 is divided into a first propeller shaft 2A (also referred to as intermediate shaft 2A) on the transfer side and a second propeller shaft 2B on the drive wheel side. The first propeller shaft 2A is connected to the second propeller shaft 2B via a second joint 3 (also referred to as constant velocity joint 3). The first propeller shaft 2A and the second propeller shaft 2B may be collectively referred to as the propeller shaft 2.

[0026] The first propeller shaft 2A is connected to the transfer via a first joint 4. The first joint 4 transmits the power output from the transfer to the first propeller shaft 2A. Therefore, the power output from the transfer is transmitted to the first propeller shaft 2A via the first joint 4.

[0027] The constant velocity joint 3 includes the seal structure 1 of the present invention, which will be described later. The constant velocity joint 3 transmits the power transmitted to the first propeller shaft 2A to the propeller shaft 2 at a constant speed. Therefore, the power transmitted to the first propeller shaft 2A is transmitted to the second propeller shaft 2B via the constant velocity joint 3. The constant velocity joint 3 also absorbs the relative movement (angle change) between the first propeller shaft 2A and the second propeller shaft 2B. The constant velocity joint 3 includes a joint cup 40 (see FIG. 2) on the rear end side.

[0028] The second propeller shaft 2B is connected to the joint cup 40. The first propeller shaft 2A is connected to the front end side of the joint cup 40, and the second propeller shaft 2B is connected to the rear end side.

[0029] The power (rotation) of the first propeller shaft 2A is transmitted to the second propeller shaft 2B via a constant velocity joint 3. The second propeller shaft 2B is provided with a dynamic damper 43. The dynamic damper 43 is intended to suppress resonance of the second propeller shaft 2B. In addition, a third joint 5 is connected to the rear end side of the second propeller shaft 2B.

[0030] The third joint 5 is connected to a differential gear (not shown) of the drive wheels (rear wheels). Therefore, the power transmitted to the second propeller shaft 2B is transmitted to the drive wheels via the third joint 5 and the differential gear.

[0031] As shown in Figures 2 and 3(a), the seal structure 1 is disposed in a constant velocity joint 3 and includes a boot 10. The boot 10 is formed in a substantially cylindrical shape from an elastic member such as rubber, and the first propeller shaft 2A (propeller shaft 2) is inserted through the center. In other words, the boot 10 is provided so as to cover the outer periphery of the first propeller shaft 2A. The boot 10 includes a band fastening portion 15, a boot lip portion 20, an intermediate portion 25, a ventilation portion 30, and the like.

[0032] The band fastening portion 15 is located on the rear end side (base end side) of the boot 10. The band fastening portion 15 can be fastened to the propeller shaft 2 by fastening the boot 10 from the outer periphery side with a band 42. Here, the band 42 is formed into an annular shape using a material such as resin or metal, and its diameter is reduced by caulking or fastening with a screw or the like.

[0033] As shown in Fig. 2, the band fastening portion 15 includes a boot inner tubular portion 16 whose diameter is enlarged in a tapered shape toward the rear end side. A bent portion 17 bent toward the front side is formed on the rear end side of the boot inner tubular portion 16. The bent portion 17 is located on the front surface of the joint cup 40. A boot outer tubular portion 18 is formed on the front end side (tip side) folded back toward the front side at the bent portion 17. The boot outer tubular portion 18 is engaged with the outer tube of the joint cup 40. In this way, the boot 10 prevents grease between the first propeller shaft 2A (propeller shaft 2) and the inside of the constant velocity joint 3 from leaking out to the outside.

[0034] The boot lip portion 20 is formed integrally as the boot 10. The boot lip portion 20 is formed so as to extend along the axial direction of the first propeller shaft 2A (propeller shaft 2) and to cover the outer circumferential side of the first propeller shaft 2A. The boot lip portion 20 has a lip-shaped tip and is elastically deformed in the inner diameter direction due to appropriate elasticity, with the inner circumferential surface coming into contact with the first propeller shaft 2A. This improves the sealing performance (airtightness) of the boot 10.

[0035] 2 and 3(a), the intermediate portion 25 is formed integrally with the boot 10. The intermediate portion 25 is formed along the axial direction of the propeller shaft 2, and is formed midway in the axial direction with respect to the band fastening portion 15 and the boot lip portion 20. Although details will be described later, a circumferential groove 32A is formed on the inner wall of the intermediate portion 25 along the outer periphery of the first propeller shaft 2A.

[0036] The ventilation section 30 communicates between the inside and the outside of the constant velocity joint 3. The ventilation section 30 is formed of three ventilation passages: a band fastening portion side ventilation passage 31, an intermediate portion ventilation passage 32, and a boot lip portion side ventilation passage 33.

[0037] The band fastening part side ventilation passage 31 is formed along the axial direction of the first propeller shaft 2A at the position where the band fastening part 15 is provided. As shown in FIG. 3(b), the opening of the band fastening part side ventilation passage 31 is formed to have a semi-elliptical shape facing upward with the first propeller shaft 2A side as the center. The band fastening part side ventilation passage 31 is reduced in diameter to an extent that ventilation is possible (for example, 2 mm diameter) when the band fastening part 15 is fastened with the band 42. In addition, the band fastening part side ventilation passage 31 is disposed at a predetermined angle (in the present embodiment, in the upward direction of 90 degrees) in the circumferential direction of the band fastening part 15. Note that the band fastening part side ventilation passage 31 may be formed to have a diameter that communicates with the outside of the constant velocity joint 3 when fastened with the band 42. As a result, ventilation through the band fastening part side ventilation passage 31 can be ensured even when fastened with the band 42.

[0038] The intermediate ventilation passage 32 is formed at a position where the intermediate portion 25 is provided. The intermediate ventilation passage 32 is formed as a circumferential groove 32A on the inner wall of the intermediate portion 25 along the outer periphery of the first propeller shaft 2A. That is, the intermediate ventilation passage 32 is formed in an annular shape around the outer periphery of the first propeller shaft 2A.

[0039] The circumferential groove 32A communicates with the band fastening portion side ventilation passage 31 and the boot lip portion side ventilation passage 33. Therefore, the circumferential groove 32A functions as the intermediate portion ventilation passage 32. The circumferential groove 32A reduces the radial thickness of the intermediate portion 25, thereby reducing the rigidity of the intermediate portion 25. As a result, the circumferential groove 32A can elastically deform the tip side of the boot lip portion 20 in the inward radial direction starting from the circumferential groove 32A.

[0040] In this manner, in the present embodiment, the circumferential groove 32A is formed along the circumferential direction of the inner wall of the intermediate portion 25, so that the intermediate portion ventilation passage 32 can be prevented from extending in the axial direction of the propeller shaft 2. Therefore, according to the above-described seal structure 1, it is expected that the boot 10 can be made compact. In addition, the circumferential groove 32A can elastically deform the tip side of the boot lip portion 20 in the inner diameter direction starting from the circumferential groove 32A, so that the tip side of the boot lip portion 20 can be brought into contact with the first propeller shaft 2A. As a result, the above-described seal structure 1 can effectively prevent foreign matter and the like from entering the inside of the constant velocity joint 3 from the tip side of the boot lip portion 20, and can prevent grease from leaking from the inside of the constant velocity joint 3 to the outside.

[0041] The boot lip side ventilation passage 33 is formed along the axial direction of the first propeller shaft 2A at the position where the boot lip 20 is provided. The boot lip side ventilation passage 33 is disposed at a different angle (out of phase) in the circumferential direction of the propeller shaft 2 with respect to the band fastening side ventilation passage 31. The boot lip side ventilation passage 33 has an inner side opening end 33A that opens toward the intermediate ventilation passage 32 and an outer side opening end 33B that opens toward the outer side of the boot lip 20. That is, in this embodiment, the ventilation section 30 is formed of three ventilation passages, the band fastening side ventilation passage 31, the intermediate ventilation passage 32, and the boot lip side ventilation passage 33, and each ventilation passage is disposed so as not to be linear along one direction (for example, a labyrinth structure in which each ventilation passage is disposed in a maze shape).

[0042] Therefore, the above-mentioned seal structure 1 can set a long distance from the outside to the inside of the constant velocity joint 3 while ensuring the escape of air from the inside of the constant velocity joint 3. As a result, the above-mentioned seal structure 1 can effectively suppress the intrusion of water, foreign matter, etc. from the outside of the constant velocity joint 3 while suppressing an increase in pressure on the inside of the constant velocity joint 3. In addition, the above-mentioned seal structure 1 can suppress an increase in internal pressure in the constant velocity joint 3 when the constant velocity joint 3 is assembled to a shaft such as the propeller shaft 2, thereby improving the workability during assembly. This is expected to reduce costs by reducing the number of work steps. In addition, the above-mentioned seal structure 1 can suppress the intrusion of foreign matter, etc. from the outside of the constant velocity joint 3, thereby suppressing damage to the constant velocity joint 3 and the propeller shaft 2.

[0043] As shown in FIG. 4(a), the boot lip side ventilation passage 33 is tapered from the inner side opening end 33A to the outer side opening end 33B in a cross-sectional view along the axial direction of the propeller shaft 2 (BB direction, see FIG. 3). In other words, the boot lip side ventilation passage 33 is tapered so as to be tapered from the inner side opening end 33A to the outer side opening end 33B in a cross-sectional view along the axial direction of the propeller shaft 2. Here, the opening diameter at the inner side opening end 33A is formed to be, for example, 2 mm, and the opening diameter at the outer side opening end 33B is formed to be, for example, 1 mm. Therefore, the above-mentioned seal structure 1 can effectively suppress the intrusion of foreign matter from the outer side of the constant velocity joint 3, and can facilitate the escape of air from the inner side of the constant velocity joint 3. The opening diameters of the inner side opening end 33A and the outer side opening end 33B can be changed to various diameters depending on the form of use.

[0044] As shown in Fig. 4(a), an elastic member 34 is provided at the outer opening end 33B. The elastic member 34 is formed, for example, from rubber. The elastic member 34 may be formed integrally with the boot lip portion 20. For example, the elastic member 34 may be formed by utilizing burrs or the like of the boot lip portion 20. The elastic member 34 is formed so as to protrude from the outer opening end 33B toward the outer side of the constant velocity joint 3.

[0045] Moreover, in a cross-sectional view taken along the axial direction of the propeller shaft 2 (in the illustrated BB direction, see FIG. 3), the elastic member 34 is tapered from the outer opening end 33B toward the outer side of the constant velocity joint 3. Specifically, the opening diameter of the inner side (the boot lip portion 20 side) of the elastic member 34 is formed to be, for example, 1 mm, and the opening diameter of the opening end 34A of the elastic member 34 is formed to be smaller than 1 mm. Therefore, the above-described seal structure 1 can more effectively prevent foreign matter and the like from entering from the outer side of the constant velocity joint 3, and can more smoothly allow air to escape from the inner side of the constant velocity joint 3.

[0046] Furthermore, the elastic member 34 elastically deforms so that the diameter of the opening end 34A side increases when there is air flow from the inside to the outside of the constant velocity joint 3, and elastically deforms so that the diameter of the opening end 34A side remains the same or decreases when there is no air flow from the inside to the outside of the constant velocity joint 3. That is, the above-described seal structure 1 can cause the elastic member 34 to function as a one-way valve.

[0047] In this way, when there is air flow from the inside to the outside of the constant velocity joint 3, the elastic member 34 elastically deforms so as to expand in diameter, thereby effectively suppressing an increase in internal pressure of the constant velocity joint 3. This allows the above-described seal structure 1 to improve workability when assembling the constant velocity joint 3. Furthermore, when there is no air flow from the inside to the outside of the constant velocity joint 3, the above-described seal structure 1 elastically deforms so that the diameter of the elastic member 34 on the opening end 34A side is maintained or reduced, thereby effectively suppressing the intrusion of foreign matter and the like from the outside of the constant velocity joint 3.

[0048] Also, the elastic member 34 may be formed so that the rigidity of the inner surface side at the base end side is higher than the rigidity of the tip end side. By configuring the above-mentioned seal structure 1 in this way, the diameter of the opening end 34A side of the elastic member 34 can be reliably expanded, maintained, or reduced depending on the ventilation state of the constant velocity joint 3. As a result, the above-mentioned seal structure 1 can suppress an increase in internal pressure in the constant velocity joint 3 when the constant velocity joint 3 is assembled to a shaft such as the propeller shaft 2, thereby improving the workability during assembly. Also, the above-mentioned seal structure 1 can suppress the intrusion of foreign matter and the like from the outside of the constant velocity joint 3, thereby suppressing damage to the constant velocity joint 3 and the propeller shaft 2.

[0049] The configuration and effects of the seal structure 1 according to one embodiment of the present invention have been described above, but the seal structure 1 of the present invention is not limited to the above-described embodiment and can be modified in various ways.

[0050] In this embodiment, the seal structure 1 is employed in a constant velocity joint 3 used in a propeller shaft 2, but the seal structure 1 of the present invention can be used in various rotating shafts and connecting parts (joints). The shape and size of the boot 10 can be changed to various shapes and sizes according to the shape and size of the propeller shaft 2 and the constant velocity joint 3. The shapes and sizes of the band fastening portion 15, the boot lip portion 20, the intermediate portion 25, and the ventilation portion 30 can be changed to various shapes and sizes.

[0051] In this embodiment, the band fastening portion side air passage 31, the intermediate portion air passage 32, and the boot lip portion side air passage 33 are each formed in a single number, but these may be formed in a plurality of numbers as necessary. The band fastening portion side air passage 31 and the boot lip portion side air passage 33 may be disposed at various angles as long as they are disposed at different angles in the circumferential direction with respect to the propeller shaft 2. For example, the band fastening portion side air passage 31 and the boot lip portion side air passage 33 may be disposed at positions that differ by 45 degrees or 90 degrees in the circumferential direction with respect to the propeller shaft 2.

[0052] In this embodiment, the boot lip side ventilation passage 33 is tapered from the inner opening end 33A to the outer opening end 33B in a cross-sectional view, but the shape of the boot lip side ventilation passage 33 is not limited to this, and various shapes and sizes can be used. For example, the boot lip side ventilation passage 33 can be tapered in various shapes, such as a meandering shape or a straight shape. In addition, the degree of diameter reduction of the boot lip side ventilation passage 33 is not limited to that in the above-mentioned embodiment, and can be tapered to various degrees.

[0053] In this embodiment, the elastic member 34 is provided at the outer side opening end 33B of the boot lip side ventilation passage 33, but the elastic member 34 may be provided as necessary, and it is also possible to configure without providing the elastic member 34. In addition, in this embodiment, rubber is used for the elastic member 34, but various materials having elasticity can be used for the elastic member 34. For example, the elastic member 34 may be formed of resin or the like. In addition, in this embodiment, the elastic member 34 is formed integrally with the boot lip portion 20, but the elastic member 34 may not only be formed integrally with the boot lip portion 20, but may also be formed separately. In addition, various shapes and sizes of the elastic member 34 can be used depending on the form in which it is used. In addition, in this embodiment, the elastic member 34 is reduced in diameter from the outer side opening end 33B toward the outside of the constant velocity joint 3, but the degree of reduction in diameter, the opening diameter, etc. can be changed as appropriate. In addition, the state of elastic deformation of the elastic member 34 is not limited to the above-mentioned embodiment, and various changes are possible.

[0054] In this embodiment, a circumferential groove 32A is formed as the intermediate ventilation passage 32 on the inner wall of the intermediate portion 25, but the intermediate ventilation passage 32 is not limited to the circumferential groove 32A and can be formed in various shapes and sizes. Also, in this embodiment, the tip side of the boot lip portion 20 is elastically deformed in the inner diameter direction starting from the circumferential groove 32A, but the present invention is not limited to this and the tip side of the boot lip portion 20 can be elastically deformed by various means. For example, various means can be used, such as changing the rigidity of the tip side and base end side of the boot lip portion 20 by changing the material or by using a separate member.

[0055] The above are various embodiments and modifications of the sealing structure according to the present invention. However, the present invention is not limited to those exemplified in the above-mentioned embodiments and modifications, and it will be easily understood by those skilled in the art that other embodiments are possible in accordance with the teachings and spirit of the present invention without departing from the scope of the claims. [Industrial Applicability]

[0056] The seal structure of the present invention can be used in the connection parts of various rotating shafts (propeller shafts, etc.) used in vehicles and the like. [Explanation of symbols]

[0057] 1:Seal structure 2: Propeller shaft 2A: Intermediate shaft (first propeller shaft) 2B: 2nd propeller shaft 3: Constant velocity joint (second joint) 10: Boots 15: Band fastening part 16: Inner cylinder of the boot 17: Bend 18: Outer cylinder of boots 20: Boot lip 25: Middle section 30: Ventilation section 31: Band fastening side ventilation passage 32: Middle ventilation passage 32A: Peripheral groove 33: Boot lip side ventilation passage 40: Joint cup

Claims

1. A seal structure of a constant velocity joint used in a propeller shaft, A boot is provided to cover an outer circumferential side of the propeller shaft, The boot is a band fastening portion that fastens to the propeller shaft by fastening from an outer circumferential side; a boot lip portion that is formed to extend along the axial direction of the propeller shaft and covers an outer circumferential side of the propeller shaft; an intermediate portion formed intermediately in the axial direction with respect to the band fastening portion and the boot lip portion; a ventilation portion that communicates the inside and the outside of the constant velocity joint; Equipped with The ventilation portion is a band fastening portion side air passage formed along an axial direction of the propeller shaft at a position where the band fastening portion is provided; An intermediate ventilation passage formed at a position where the intermediate portion is provided; a boot lip side ventilation passage formed along the axial direction of the propeller shaft at a position where the boot lip is provided; Equipped with An elastic member is provided at an end of the boot lip side ventilation passage, The elastic member protrudes from an end portion toward an outer side of the constant velocity joint and has a diameter that decreases toward the outer side, A seal structure characterized in that the band fastening portion side air passage and the boot lip portion side air passage are arranged at different angles in the circumferential direction of the propeller shaft.

2. The boot lip side ventilation passage is An inner opening end that opens toward the intermediate ventilation passage; An outer opening end that opens toward the outer side of the boot lip portion; It has The seal structure according to claim 1 , wherein in a cross-sectional view, the diameter of the seal structure decreases from the inner opening end to the outer opening end.

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