JP2008281097A - Boot and power transmission shaft - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent an increase of internal pressure of a boot mounted on a joint portion of a power transmission shaft when contracting the joint portion, without increasing the number of parts. <P>SOLUTION: The boot 3 includes a bellows section 33 between a large-diameter portion 31 and a small-diameter portion 32 thereof. The bellows section 33 has a normal part 33a having a diameter that gradually becomes smaller from the large-diameter portion 31 toward the small-diameter portion 32, and an easily-contractible part 33b axially extending from the small-diameter portion 32 side of the normal part 33a toward the small-diameter portion 32. The thickness of the easily-contractible part 33b is set to be smaller than that of the normal part 33a so that the easily-contractible part 33b is contracted more easily than the normal part 33a when axial compression force is applied to the bellows section 33 from both sides thereof. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a boot attached to a joint portion of a power transmission shaft, and a power transmission shaft to which the boot is attached.

  Power transmission shafts such as drive shafts and propeller shafts are used in vehicles such as automobiles. Many of these power transmission shafts have a joint portion such as a constant velocity universal joint in the middle thereof. The joint part basically transmits rotational driving force by inserting the other shaft end part into the joint case (for example, outer race) at one shaft end part and mutually engaging in the rotation direction. It has a structure to do.

  A boot is attached to the joint portion, and a lubricant such as grease is sealed in the joint portion by the boot, and foreign matter such as dust is prevented from entering the joint portion.

  The boot includes a large-diameter portion that is attached to the outer periphery of the joint case provided at the end portion of the one shaft, and a small-diameter portion that is attached to an intermediate position of the other shaft. Further, the boot has a bellows-like portion between the large-diameter portion and the small-diameter portion in order to easily follow deformation such as bending and expansion / contraction of the joint portion.

  Patent Literature 1 discloses a drive shaft including a tripod type constant velocity joint that can be expanded and contracted in the axial direction and that can be bent, and a boot mounted on the joint portion.

  Such axially expandable and contractible joints are used in joints such as drive shafts and propeller shafts, and when the drive shafts and propeller shafts are assembled in a vehicle, the assembly work is performed while the joints are contracted. It may be done.

  For example, when a drive shaft is assembled between a differential and a hub of a vehicle whose arrangement has already been determined, the drive shaft cannot be assembled in a state where the drive shaft is longer than between the differential and the hub. Therefore, the assembly work is performed after the drive shaft is once contracted at the joint by an assembly operator or the like. The same applies when a propeller shaft that is longer than the gap between the transmission and the rear differential that is already arranged is assembled.

  The boot disclosed in Patent Document 2 is formed such that the thickness of the valley portion of the bellows-like portion is gradually increased from the small diameter portion side toward the large diameter portion side. This boot is attached to a barfield type constant velocity joint that cannot be expanded and contracted in the axial direction and can only be bent, and is intended to solve a problem that occurs when the joint portion is bent. That is, this boot has the problem that the bellows-like folds of the boot are in close contact with each other when the joint part is bent, and the folds of the bellows-like part tend to be worn away. The problem is solved by increasing the thickness.

The boot disclosed in Patent Document 3 has a bellows-like portion separated into two pieces in the axial direction via a connecting portion. A hard rigid resin is used for the bellows-like portion on the large-diameter portion side, and a soft material is used for the bellows-like portion on the small-diameter portion side. The connecting portion is provided so as to be in sliding contact with the outer peripheral surface of the drive shaft. This boot is also attached to the bar field type constant velocity joint, and aims to solve the problem caused when the joint portion is bent. That is, in this boot, the tensile stress acting on the bellows-like portion on the large-diameter portion side is reduced by sliding the connecting portion in the axial direction when the joint portion is bent.
JP 2004-108435 A (FIG. 1) 6-82463 Reality 8-5377

  By the way, when a drive shaft or a propeller shaft having a joint part that can be expanded and contracted in the axial direction as disclosed in Patent Document 1 is contracted during assembly work, the internal pressure in the joint part sealed by the boot is reduced. It rises greatly and this works against the force that tries to contract the shaft. As a result, a large force is required to contract the shaft, which may hinder the assembly work.

  Moreover, there is a possibility that abnormal deformation may occur in the bellows-like portion of the boot due to an increase in internal pressure in the joint portion.

  The boot disclosed in Patent Document 2 is not attached to the extendable joint part, but if the boot is attached to the extendable joint part and the shaft including the joint part is contracted However, the same problem as above occurs.

  The boot disclosed in Patent Document 3 has a problem in that the number of parts increases because the bellows-like portion has a two-piece structure. Furthermore, there is a problem in that the reliability of the seal in the entire boot is lowered due to the increase in the joint portion, and that the entire boot is lengthened in the axial direction.

  The present invention has been made in view of the above problems, and when the power transmission shaft is contracted at the joint portion, the boot for suppressing an increase in internal pressure of the boot attached to the joint portion and the boot are attached. An object is to provide a power transmission shaft. It is another object of the present invention to provide a boot capable of suppressing the increase in internal pressure without increasing the number of parts and a power transmission shaft equipped with the boot.

  As means for solving the above-described problems, the boot and the power transmission shaft of the present invention are configured as follows. That is, the boot according to the present invention is a boot having a bellows-like portion between a large-diameter portion and a small-diameter portion, wherein the bellows-like portion is gradually reduced in diameter from the large-diameter portion side toward the small-diameter portion side. And an easy-compression portion formed by extending from the small-diameter portion side of the general portion to the small-diameter portion side in the axial direction. Furthermore, when the axial compression force is applied from both outer sides of the bellows-like portion, the thickness of the easily compressible portion is such that the easily compressible portion is more easily compressed than the general portion. It is set thinner. Here, the thickness of the easily compressible portion is set to be thinner than the thickness of the general portion. The thickness of the easily compressible portion is that of the general portion in any of the peak portion, the valley portion, and the slope portion. It means that it is thinner than the wall thickness.

  Further, the bellows-shaped portion is any one of the peak portion, the valley portion, and the slope portion so that when the axial compressive force is applied from both outer sides thereof, the easily compressible portion is more easily compressed than the general portion. In this case, the thickness of the easily compressible portion may be set thinner than the thickness of the general portion. However, the thickness of each part of the easily compressible part can be made evenly thinner if the thickness of the easily compressible part is set thinner than the thickness of the general part in any of the peak part, valley part and slope part. It is advantageous in terms of strength, durability and the like.

  Moreover, the said structure WHEREIN: The said large diameter part, the said small diameter part, the said general part, and the said easy compression part may be shape | molded as an integrated object.

  The power transmission shaft of the present invention includes a joint case formed at one shaft end, and the other shaft that is engaged in the rotational direction and slidably inserted in the axial direction in the joint case. And a power transmission shaft having a joint portion provided with an end portion. Any one of the boots is mounted on the joint portion. The large-diameter portion of the boot is fixed to the outer peripheral side of the joint case, and the small-diameter portion is fixed to the middle position of the other shaft.

  According to the boot and the power transmission shaft, when the power transmission shaft is expanded and contracted at the joint portion, the easily compressing portion is more easily compressed than the general portion of the boot. Since the volume average per axial unit length in the easily compressible part is much smaller than that of the general part, the easily compressible part is compressed more easily than the general part, so that the area sealed by the boot is reduced. The decrease in volume can be suppressed as compared with the conventional one, and the pressure increase in the boot can also be suppressed. As a result, the drag generated when the power transmission shaft contracts is suppressed, and the power transmission shaft can be easily contracted.

  In addition, since an increase in pressure in the boot when the power transmission shaft contracts is suppressed, abnormal deformation of the bellows-like portion is also prevented.

  In addition, when the large-diameter portion, the small-diameter portion, the general portion, and the easy-compression portion are molded as a single body, without increasing the number of parts, without impairing the sealing performance, The advantages described above are obtained.

  According to the boot and the power transmission shaft according to the present invention, the easily compressing portion is compressed more easily than the general portion, so that the volume reduction of the region sealed by the boot is suppressed as compared with the conventional case, and the pressure inside the boot is also increased. It can be suppressed. As a result, the drag generated when the power transmission shaft contracts is suppressed, and the power transmission shaft can be easily contracted.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a partial cross-sectional view showing a state in which a boot 3 is attached to a joint portion 2 on the inboard side of a drive shaft 1 that is a power transmission shaft.

<Description of joint part>
The joint portion 2 on the inboard side of the drive shaft 1 employs a tripod type constant velocity joint as a joint portion that can expand and contract in the axial direction. The joint portion 2 includes a joint case 4a formed at an end portion of one shaft 4 and an end portion of the other shaft 5 inserted into the joint case 4a. The joint case 4a and the end of the other shaft 5 inserted into the joint case 4a engage with each other in the rotational direction, and the other shaft 5 has an end in the axial direction with respect to the inside of the joint case 4a. It is slidably inserted.

  The one shaft 4 is an output shaft 4 connected to the differential side, and the other shaft 5 is an intermediate shaft connected between the output shaft 4 and an outboard shaft (not shown in FIG. 1). 5. The joint portion 2 includes a joint case 4a, an in-cylinder member 6 inserted into the joint case 4a, a roller 7, and the like.

  The in-cylinder member 6 is fitted and fixed to the outer periphery on one end side of the intermediate shaft 5. A trunnion 6a projecting radially outward is provided at several locations on the outer diameter side of the in-cylinder member 6, and a roller 7 is rotatably mounted on the outer periphery of each trunnion 6a via a bearing. ing.

  The joint case 4a has a bottomed cylindrical shape in which the insertion side of the intermediate shaft 5 is opened and the output shaft 4 side is closed. In several places on the inner diameter side of the joint case 4a, linear grooves 4b are formed along the axial direction, and the roller 7 is disposed so as to be able to roll in the axial direction. Therefore, with this configuration, the end portion of the shaft 5 is slidable in the axial direction with respect to the inside of the joint case 4a.

  In addition, the outer peripheral surface of the joint case 4a has a non-cylindrical shape in which a region on the back outer diameter side of the linear groove 4b bulges outward in the radial direction, and other regions are recessed inward in the radial direction. Therefore, in order to easily and surely attach the boot 3 to the joint case 4a, an adapter 8 for correcting the unevenness of the outer peripheral surface of the joint case 4a into a cylindrical shape is externally attached to the outer peripheral surface of the joint case 4a. Yes. Therefore, the inner diameter side of the adapter 8 has a shape corresponding to the unevenness of the outer peripheral surface of the joint case 4a, and the outer side is cylindrical.

<Description of boots>
As shown in FIG. 1, the boot 3 is attached to the joint portion 2 so as to close the opening of the joint portion 2, and a lubricant such as grease is sealed in the joint portion 2 by the boot 3. Yes.

  The boot 3 (that is, a large-diameter portion 31, a small-diameter portion 32, and a bellows-like portion 33, which will be described later) is formed as an integral body. Various manufacturing methods can be employed for manufacturing the boot 3. For example, TPEE (thermoplastic polyester elastomer) injection compression molding, chloroprene rubber injection molding, polyester resin blow molding, and the like can be employed. The shape and thickness of the boot 3 can be set according to molding conditions such as a mold to be used, injection conditions, and compression conditions.

  The boot 3 has a large-diameter portion 31 and a small-diameter portion 32 at both ends thereof, and a bellows-like portion 33 therebetween.

  The large-diameter portion 31 is fixed to the outer peripheral side of the joint case 4a through the adapter 8. An inner peripheral convex portion 31 a is formed on the inner peripheral surface of the large-diameter portion 31, and this is fitted and attached to a peripheral groove 8 a formed on the outer peripheral surface of the adapter 8. Further, a fastening belt 9 is fastened to the outer diameter side of the large diameter portion 31. This prevents the large-diameter portion 31 of the boot 3 from being detached from the joint case 4a, and at the same time, sealability (airtightness) within the boot 3 is ensured.

  On the other hand, the small-diameter portion 32 is fixed to an intermediate position of the intermediate shaft 5. An inner circumferential convex portion 32 a is formed on the inner circumferential surface of the small-diameter portion 32, and this is fitted and attached to the circumferential groove 5 a formed at the midway position of the intermediate shaft 5. Further, the fastening belt 10 is fastened to the outer diameter side, the small-diameter portion 32 is prevented from being displaced from the intermediate position of the intermediate shaft 5, and the sealing performance (airtightness) in the boot 3 is also secured. Yes.

  A general portion 33a is formed on the bellows-like portion 33 on the large-diameter portion 31 side, while an easy-compressing portion 33b is formed on the small-diameter portion 32 side.

  The general portion 33a is formed in a bellows shape that is gradually reduced in diameter from the large-diameter portion 31 side toward the small-diameter portion 32 side.

  The easy compression part 33b is formed in the bellows shape extended from the small diameter part 32 side of the general part 33a to the axial small diameter part 32 side. That is, the easily compressing part 33b extends in a bellows shape toward the small-diameter part 32 in the axial direction without gradually increasing or decreasing the diameter from the gradually decreasing end part of the general part 33a. In addition, the space | interval of the trough part 33ba of the easy compression part 33b and the intermediate shaft 5 is ensured at least to such an extent that the air flow in the axial direction within the easy compression part 33 is not inhibited.

  When the axial compression force is applied from both outer sides of the bellows-like portion 33, that is, when the drive shaft 1 is contracted in the joint portion 2, the general portion 33a and the easy compression portion 33b are replaced with the general compression portion 33b. The thicknesses of the easily compressing portion 33b and the general portion 33a are set so as to be more easily compressed. Here, the easy compression part 33b is more easily compressed than the general part 33a when the axial compression force acts from both outer sides of the bellows-like part 33 per unit length in the axial direction of the easy compression part 33b. This means that the amount of shrinkage is larger than that of the general part 33a.

  In order for the easy compression part 33b to be more easily compressed than the general part 33a, the peak parts 33ab, 33bb, the valley parts 33aa, 33ba, and the slope parts 33ac, 33bc (intermediate part between the peak part and the valley part) The wall thickness of the easy compression part 33b may be made thinner than the wall thickness of the general part 33a. However, it is not sufficient to simply make it thin, and it is necessary to make the thickness of the easy compression portion 33b sufficiently thin to such an extent that the easy compression portion 33b is more easily compressed than the general portion 33a.

  Alternatively, in any one or two of the peaks 33ab, 33bb, valleys 33aa, 33ba, and slopes 33ac, 33bc, the thickness of the easily compressible portion 33b may be set to be smaller than the thickness of the general portion 33a. The easily compressing part 33b can be compressed more easily than the general part 33a. That is, even if the portion to be set thin is any one or two of the peak portion 33bb, the valley portion 33ba, and the slope portion 33bc of the easy compression portion 33b, the easy compression portion 33b is a general portion depending on the degree of thinning. It can be compressed more easily than 33a. In this case as well, it is not sufficient to simply make it thin, and it is necessary to sufficiently reduce the thickness of the portion of the easy compression portion 33b to such an extent that the easy compression portion 33b is more easily compressed than the general portion 33a.

<About the action of the boot when the drive shaft contracts>
Next, a case where the drive shaft 1 is contracted at the joint portion 2 will be described.

  When the drive shaft 1 (see FIG. 1) that is extended at the joint portion 2 is contracted in the axial direction (see FIG. 2), the small-diameter portion 32 and the large-diameter portion 31 of the boot 3 approach each other in the axial direction. To do. Therefore, an axial compression force acts on the bellows-like portion 33 formed between the small-diameter portion 32 and the large-diameter portion 31 from both outer sides, and the bellows-like portion 33 is compressed in the axial direction.

  At this time, in the bellows-shaped part 33, the easy compression part 33b is compressed more easily than the general part 33a. Since the average value of the volume per unit length in the axial direction in the easily compressing portion 33b is much smaller than the average value of the volume per unit length in the axial direction in the general portion 33a, the area sealed by the boot 3 The volume does not change much before and after compression of the bellows-like portion 33. As a result, the pressure increase in the boot 3 is greatly suppressed as compared with the conventional case, and the operator can easily contract the drive shaft 1 with a small force. Further, by suppressing the pressure increase in the boot 3 when the drive shaft 1 is contracted, abnormal deformation of the bellows-like portion 33 of the boot 3 is prevented.

<About drive shaft assembly work>
3 and 4 are views showing a state when the drive shaft 1 is assembled between the differential 11 and the hub 12 of the vehicle. The outboard shaft 13 is jointed to the outboard side of the intermediate shaft 5 via a bar field type constant velocity joint portion 14 that does not expand and contract in the axial direction. Further, a well-known bellows-like boot 15 is attached to the joint portion 14. The schematic diagrams shown above and below the hub 12 show the suspension 16 and the lower arm 17, respectively. The hub 12 and the suspension 16 are tilted from the bottom upward to the outside at a maximum angle.

  First, since the drive shaft 1 cannot be disposed between the hub 12 and the differential 11 when the drive shaft 1 is extended, the drive shaft 1 is contracted at the joint portion 2 by an operator or the like. At this time, since the boot mounted on the joint portion 2 is the boot 3 according to the embodiment of the present invention, the operator can easily contract the drive shaft 1 with a small force.

  As shown in FIG. 3, in the drive shaft 1 contracted to the full length V, the output shaft 4 is fitted into the differential 11, and one end side of the outboard shaft 13 is disposed in the vicinity of the insertion hole 12 a of the hub 12.

  Next, as shown in FIG. 4, the drive shaft 1 is extended to the original length W by an operator or the like, and the tilted hub 12 and suspension 16 are located between a lower arm 17 and the hub 12. One end side of the outboard shaft 13 is inserted into the insertion hole 12 a of the hub 12 while being rotated upright around the fulcrum. When the drive shaft 1 is extended, the internal pressure in the boot 3 is slightly high when the joint portion 2 is contracted, so that the operator can only drive the drive shaft 1 by loosening the hand or by extending the drive shaft 1 with a light force. The length of the shaft 1 can be easily restored.

<Assembly work of propeller shaft>
5 and 6 show that when the propeller shaft 21 attached to the joint portion 2 ′ to which the boot 3 can be extended and retracted is assembled between the transmission 22 and the rear differential 23 of the vehicle whose arrangement is already fixed. It is a figure which shows the state of. A tripod constant velocity joint is also employed in the joint portion 2 ′ of the propeller shaft 21.

  First, since the propeller shaft 21 cannot be disposed between the transmission 22 and the rear differential 23 in an extended state, the propeller shaft 21 is contracted at the joint portion 2 ′ by an operator or the like. At this time, since the boot attached to the joint portion 2 ′ is the boot 3 according to the embodiment of the present invention, the operator or the like can easily contract the propeller shaft 21 with a small force.

  Then, as shown in FIG. 5, the propeller shaft 21 contracted and bent at the joint portion 2 ′ to the total length of about X is connected to the front propeller shaft 21a on the transmission 22 side by a bolt and a nut 23f via the joint portion 21c. Is done. Further, the bolt insertion hole of the joint flange 21e of the joint portion 21d on the rear side of the rear propeller shaft 21b is disposed in the vicinity of the mounting bolt 23a of the rear differential 23. The joint portions 21c and 21d are joint portions that are not expandable / contractible in the axial direction.

  Next, as shown in FIG. 6, the propeller shaft 21 is extended to the original length Y by an operator or the like, and the bolt insertion hole of the joint flange 21 e is inserted into the mounting bolt 23 a of the rear differential 23. The joint flange 21e and the rear differential 23 are fastened to each other by a mounting bolt 23a and a nut 23f. When the propeller shaft 21 is extended, the internal pressure in the boot 3 is slightly high when the joint portion 2 ′ is contracted. Therefore, the operator only needs to loosen his hand or stretch the propeller shaft 21 with a light force. The length of the propeller shaft 21 can be easily restored.

  As described above, the boot 3 and the power transmission shafts 1 and 21 according to the embodiment of the present invention described above can be applied to a power transmission shaft having the joint portions 2 and 2 ′ that can be expanded and contracted in the axial direction. It is not limited to the drive shaft 1 and propeller shaft 21 described above. Further, the power transmission shaft is a shaft for transmitting power, and may have any joint portion 2 that can extend and contract in the axial direction, and is not limited to the power transmission shaft used in the vehicle. For example, the present invention can be applied to power transmission shafts of ships, aircraft, general industrial machines, and the like.

  The present invention can be applied to, for example, a power transmission shaft having a joint portion that can be expanded and contracted in the axial direction, such as a drive shaft and a propeller shaft of a vehicle such as an automobile, and a boot attached to the joint portion.

It is a fragmentary sectional view showing the state where boots were attached to the inboard side joint part of a drive shaft, and is a figure showing the state where a drive shaft is extended in a joint part. It is a fragmentary sectional view showing the state where boots were attached to the inboard side joint part of a drive shaft, and is a figure showing the state where a drive shaft contracts in a joint part. It is a figure which shows the state at the time of assembling | attaching between the differential and the hub of the vehicle in which arrangement | positioning has already been decided, Comprising: It is a figure which shows the state which the drive shaft is shrink | contracted in the joint part. It is a figure which shows the state at the time of assembling | attaching between the differential and the hub of the vehicle in which arrangement | positioning has already been decided, Comprising: It is a figure which shows the state which the drive shaft is extended in the joint part. It is a figure which shows the state at the time of assembling | attaching between the transmission and rear differential of a vehicle with which the arrangement | positioning has already been decided, Comprising: It is a figure which shows the state which the propeller shaft is contracting in a joint part. It is a figure which shows the state at the time of assembling | attaching between the transmission and rear differential of the vehicle in which arrangement | positioning has already been decided, Comprising: It is a figure which shows the state which the propeller shaft is extended in the joint part.

Explanation of symbols

1 Drive shaft (power transmission shaft)
2 Joint part 2 'Joint part 3 Boot 4 Output shaft (one shaft)
4a Joint case 5 Intermediate shaft (the other shaft)
21 Propeller shaft (power transmission shaft)
31 Large-aperture part 32 Small-aperture part 33 Bellows-like part 33a General part 33b Easy compression part 33aa Valley part 33ba Valley part 33ab Mountain part 33bb Mountain part 33ac Inclined part 33bc Inclined part

Claims (4)

In the boot having a bellows-like portion between the large-diameter portion and the small-diameter portion,
The bellows-shaped portion is a general portion that gradually decreases in diameter from the large-diameter portion side toward the small-diameter portion side, and an easy compression formed by extending from the small-diameter portion side of the general portion to the small-diameter portion side in the axial direction. Department, and
When the axial compression force is applied from both outer sides of the bellows-like portion, the thickness of the easily compressible portion is thinner than the thickness of the general portion so that the easily compressible portion is more easily compressed than the general portion. Boots characterized by being set. In the boot having a bellows-like portion between the large-diameter portion and the small-diameter portion,
The bellows-shaped portion is a general portion that gradually decreases in diameter from the large-diameter portion side toward the small-diameter portion side, and an easy compression formed by extending from the small-diameter portion side of the general portion to the small-diameter portion side in the axial direction. Department, and
When an axial compressive force is applied from both outer sides of the bellows-shaped part, the peak part, the valley part, or the slope part, so that the easy compression part is more easily compressed than the general part, A boot characterized in that the thickness of the easily compressible portion is set to be thinner than the thickness of the general portion.   3. The boot according to claim 1, wherein the large-diameter portion, the small-diameter portion, the general portion, and the easy-compression portion are molded as a single body. A joint part comprising: a joint case formed at one shaft end; and the other shaft end inserted into the joint case in a rotational direction and slidably inserted in the axial direction In a power transmission shaft having
The boot according to any one of claims 1 to 3, wherein the large-diameter portion is fixed to an outer peripheral side of the joint case, and the small-diameter portion is fixed to an intermediate position of the other shaft. A power transmission shaft that is mounted on a joint.

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