JP2008298271A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively restrain or prevent the leakage of a lubricant and the intrusion of a foreign matter while securing stable ventilation performance, in a constant velocity universal joint with a boot. <P>SOLUTION: A ventilation passage 31 making the inside and the outside of the joint communicate with each other is formed at the small diameter end 28b of the boot 28. The ventilation passage 31 is formed to penetrate through the small diameter end 28b of the boot 28 in a plane P parallel to the axis, and also has an inclined part 31a forming an angle in the axial direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint, and in particular, a constant velocity universal joint having a boot for sealing the inside of a joint, which is used in a propeller shaft for transmitting rotational driving force from a transmission to a differential in 4WD vehicles, FR vehicles, and the like. About.

  For example, in an FR vehicle, the engine, clutch, transmission (transmission) is arranged in the front, the reduction gear device (differential), and the drive axle are arranged in the rear. Therefore, it is usual to use a propeller shaft for power transmission during this period. is there. In addition, a rear propeller shaft and a front propeller shaft are required for a 4WD vehicle based on an FR vehicle. These propeller shafts include a constant velocity universal joint so as to be able to cope with a length displacement and an angular displacement due to a relative position change between a transmission and a differential (hereinafter simply referred to as a differential).

  FIG. 6 shows a known constant velocity universal joint. The constant velocity universal joint shown in the figure is an example of a constant velocity universal joint for a propeller shaft, and includes an inner ring 1 as an inner joint member, an outer ring 2 as an outer joint member, and a ball as a torque transmission member. 3 and a cage 4 for holding the ball 3 are provided as main components. One end opening of the outer ring 2 is sealed by an end cap 8 and the other end opening is sealed by a boot 6 and a boot adapter 7, thereby preventing leakage of lubricant (for example, grease) filled in the joint. The boot 6 integrally includes a small-diameter end 6a, a large-diameter end 6b, and an intermediate portion 6c that connects the small-diameter end 6a and the large-diameter end 6b. The small-diameter end 6a of the boot 6 is fitted to the outer peripheral surface of the shaft member 5 extending from the inner ring 2 by tightening the boot band 9 in a state where the boot band 9 is fitted in a circumferential groove 6d provided on the outer peripheral surface. ing. On the other hand, the large-diameter end 6 b of the boot 6 is connected to the outer peripheral surface of the outer ring 2 via the boot adapter 7.

  In this type of constant velocity universal joint, the boot 6 may be deformed or damaged due to internal pressure expansion due to heat generation during high speed rotation or depression during pressure reduction. In order to prevent such a problem, it is effective to balance the internal and external pressures. In order to realize this, the small diameter end portion 6a of the boot 6 is provided with an axial air passage 10 that communicates the inside and outside of the joint. For example, as shown in FIG. 6, the air passage 10 is provided with a linear groove along the axial direction on the inner peripheral surface of the small diameter end portion 6 a, and is formed by the linear groove and the outer peripheral surface of the shaft member 5 (for example, Patent Document 1).

However, in the configuration of Patent Document 1, the original function (seal function) of the boot 6 such as grease leakage and prevention of entry of foreign matter may be impaired. Therefore, for example, an annular lip is provided on one end surface on the outer side of the small-diameter end portion of the boot and the air passage is covered with this lip (for example, Patent Document 2), or the inner peripheral surface of the small-diameter end portion 6a. There has been proposed a structure in which an inclined groove having an angle with respect to the axial direction is provided, and an inclined air passage is provided between the inclined groove and the outer peripheral surface of the shaft member 5 (for example, Patent Document 3).
Japanese Utility Model Publication No. 7-44969 JP-A-8-28704 JP 2006-275259 A

  In the configuration of Patent Document 2, since the centrifugal force acts on the boot as the joint rotates and the inside and outside of the joint communicate with each other only when the lip is expanded, deformation of the boot is effectively suppressed. Thus, a sealing function is also ensured. However, since the lip is formed in an annular shape, its rigidity is relatively high. Therefore, it is difficult to expand the lip in a desired manner, and desired air permeability may not be ensured. For example, it is possible to reduce the rigidity of the lip by thinning the lip, but the boot may be damaged due to fatigue deterioration due to the opening and closing operation of the lip.

  Further, in the configuration of Patent Document 3, there is no big difference from the configuration of Patent Document 1 except that the ventilation path can be lengthened, and it is difficult to ensure a sufficient sealing function.

  The present invention has been made in view of the above-mentioned problems, and the problem is that in this type of constant velocity universal joint with a boot, the leakage and the foreign matter of the lubricant are prevented while preventing the deformation and breakage of the boot. It is to be able to effectively suppress or prevent intrusion.

  In order to solve the above problems, in the present invention, an outer joint member and an inner joint member that move relative to each other via a torque transmission member, and a shaft member that is provided between the outer joint member and the inner joint member and extends from the inner joint member. And a flexible boot that seals the inside of the joint by fitting an end to the outer peripheral surface of the joint, and a constant velocity universal joint that allows communication between the inside and outside of the joint through an axial air passage provided at the end of the boot The vent passage is formed so as to penetrate the end portion of the boot inside and outside the joint in a plane parallel to the axis, and has an inclined portion that forms an angle with respect to the axial direction. Provide constant velocity universal joints.

  As described above, if the ventilation path is formed so as to penetrate the end of the boot inside and outside the joint in a plane parallel to the axis, and has an inclined portion that forms an angle with respect to the axial direction, In the inclined portion, the radial separation distance (rotation radius) between the air passage and the rotation center of the joint gradually changes in the axial direction. In this case, the centrifugal force acting on the inclined portion of the air passage is decomposed into a component in the outer diameter direction and a component in the direction along the air passage, and the component in the direction along the air passage has a minimum turning radius. The size gradually increases from the portion toward the end. Therefore, with the above configuration, the lubricant receives a force in a direction returning to the inside of the joint along the inclined portion due to the centrifugal force, while the foreign matter is discharged outside the joint along the inclined portion by the centrifugal force. To receive power. Therefore, leakage of the lubricant and entry of foreign matter can be suitably suppressed.

  Even in the case of the above configuration, since the inside and outside of the joint are always in communication with each other through the air passage, the pressure inside and outside the joint can be balanced, and the situation where the boot is deformed due to the internal pressure expansion due to heat generation during rotation is effective. Is prevented.

  The ventilation path can be configured by only the inclined portion, and can further include a straight portion that communicates with the inclined portion and extends along the axial direction. In the former case, it is easy to form an air passage, which is advantageous over the latter configuration in terms of cost. On the other hand, in the latter case, since the centrifugal force acting on the straight portion does not have a component in the direction along the air passage, leakage of the lubricant and entry of foreign matter can be stopped at the straight portion, and the above effect is further enhanced. Remarkably obtained. In the case of a configuration having a straight portion, it is particularly desirable to provide inclined portions at both ends of the straight portion because the effect of suppressing the leakage of the lubricant and the entry of foreign matter can be obtained more remarkably.

  The ventilation path may be provided only at one place in the circumferential direction, or a plurality of ventilation paths may be provided. If the latter configuration is employed, it is possible to more effectively prevent the boot from being deformed, that is, to ensure better air permeability than the former.

  In the above configuration, it is also possible to further provide a protruding portion that protrudes into the ventilation path. With this configuration, a part of the ventilation path is narrowed, and the labyrinth seal is configured by the part. Therefore, it is possible to more reliably suppress both the leakage of the lubricant and the intrusion of foreign matter, which is desirable. The projecting portion may be provided integrally with the boot. When a partial region in the axial direction of the air passage is open on the outer peripheral surface of the shaft member, the projecting portion projects from the outer peripheral surface of the shaft member into the air passage. It may be provided as follows.

  Further, the present invention can be suitably employed regardless of whether the boot is made of rubber or a thermoplastic elastomer.

  Since the constant velocity universal joint according to the present invention has the above-mentioned characteristics, it is suitable as a constant velocity universal joint for a propeller shaft that is likely to cause a problem of heat generation due to high-speed rotation. Of course, the present invention can be applied not only to a propeller shaft but also to a constant velocity universal joint for a drive shaft, for example.

  As described above, according to the present invention, it is possible to effectively suppress or prevent the leakage of the lubricant from the inside of the joint and the entry of the foreign matter from the outside of the joint while ensuring the stable air permeability and preventing the deformation and breakage of the boot. can do. Thereby, durability and reliability improvement of a constant velocity universal joint are achieved.

  Hereinafter, a constant velocity universal joint according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a first embodiment of a constant velocity universal joint according to the present invention. Specifically, a Lebro type constant velocity universal joint (LJ) which is a kind of sliding type constant velocity universal joint used for a propeller shaft. This shows an example of the configuration. The constant velocity universal joint shown in the figure includes an inner ring 21 as an inner joint member and an outer ring 22 as an outer joint member provided so as to be relatively axially and angularly displaceable via a ball 23 as a torque transmission member. The cage 24 holding the balls 23 is provided as a main part.

  A plurality of track grooves 21 a are formed on the outer peripheral surface of the inner ring 21, and a spline 21 b is formed on the inner diameter of the center hole of the inner ring 21. A shaft member (stub shaft) 25 having a shaft portion 25a having a spline 25c formed on the outer diameter is inserted into the center hole of the inner ring 21, and the splines 21b and 25c are fitted to each other, thereby The stub shaft 25 is connected to be able to transmit torque. An annular groove 25 d is provided at the tip of the shaft portion 25 a of the stub shaft 25, and the stub shaft 25 is attached to the inner ring 21 by locking the snap ring 26 attached to the annular groove 25 d at the end surface of the inner ring 21. Retains retention. In this embodiment, the inner ring 21 and the stub shaft 25 are formed separately, but they can also be formed integrally.

  The outer ring 22 is disposed on the outer periphery of the inner ring 21, and a plurality of track grooves 22a that are paired with the track grooves 21a of the inner ring 21 are formed on the inner peripheral surface thereof. Balls 23 are respectively incorporated between the track grooves 21 a of the inner ring 21 and the track grooves 22 a of the outer ring 22 that make a pair. A cage 24 is disposed between the outer peripheral surface of the inner ring 21 and the inner peripheral surface of the outer ring 22, and the balls 23 are held in a pocket 24 a of the cage 24 so as to roll freely.

  An end cap 27 is fixed to one end side of the outer ring 22 in the axial direction by bolting, and a sealing device is attached to the other end side in the axial direction. This prevents leakage of the lubricant (here, grease) filled inside the joint and prevents foreign matter from entering from the outside of the joint. The sealing device mainly includes a boot 28 and a boot adapter 29.

  The boot 28 integrally includes a large diameter end portion 28a, a small diameter end portion 28b, and an intermediate portion 28c that connects the large diameter end portion 28a and the small diameter end portion 28b. A circumferential groove 28d is formed on the outer peripheral surface of the small diameter end portion 28b. The boot 28 is made of a flexible material, for example, a rubber material such as chloroprene rubber (CR), nitrile rubber (NBR), silicon rubber (VMQ, FVMQ), fluorine rubber (FKM, FFKM), or ester-based, olefin. It is formed by using thermoplastic elastomers such as styrene, urethane, amide, and styrene.

  The boot adapter 29 is formed in a substantially cylindrical shape having a flange 29 a fitted to the outer peripheral surface of the outer ring 22 at one end thereof, and is fixed to the outer ring 22 by bolting together with the end cap 27. The boot 28 and the boot adapter 29 are fixed by caulking one end (end portion 29b) of the boot adapter 29 on the side opposite to the flange 29a to the large-diameter end portion 28a of the boot 28.

  The stub shaft 25 is provided with an annular recess 25b, and the small-diameter end portion 28b of the boot 28 is fitted on the annular recess 25b. Then, the boot band 30 is tightened so as to be fitted in the circumferential groove 28d on the outer peripheral surface of the small diameter end portion 28b, and thereby the small diameter end portion 28b of the boot 28 is fitted into the annular recess 25b of the stub shaft 25. . Any boot band 30 can be used, and a so-called one-touch type, low profile, ring type, or the like can be used. The small-diameter end 28b of the boot 28 is set in a free state so that its inner diameter is slightly smaller than the outer diameter of the annular recess 25b, thereby ensuring the fit of the boot 28 to the annular recess 25b of the stub shaft 25. ing.

  FIG. 2A shows an enlarged cross-sectional view of the vicinity of the small diameter end portion 28b of the boot 28 (X portion in FIG. 1). As shown in the figure, the small-diameter end portion 28b of the boot 28 has an inner and outer joint in order to prevent the boot 28 from being deformed or damaged due to internal pressure expansion due to heat generation during high-speed rotation or dents during decompression. One axial air passage 31 is provided for communicating and balancing the internal and external pressures of the joint. As shown in FIGS. 2 (B) and 2 (C), the air passage 31 is formed so that the flesh portion of the small-diameter end portion 28b exists in a plane (virtual plane) P parallel to the axis so that the axis is present. It is a through-hole penetrating in the axial direction, and includes an inclined portion 31a that forms an angle with respect to the axial direction O and extends linearly. In the illustrated example, the cross-sectional shape of the air passage 31 is rectangular, but the cross-sectional shape of the air passage 31 can be arbitrarily set, and other than the rectangular shape, for example, a perfect circle shape, an oval shape, etc. You can also

  By forming the air passage 31 as described above, the radial separation distance (rotation radius) between the air passage 31 (the axial center thereof) and the rotation center gradually changes along the axial direction of the air passage 31. More specifically, as is apparent from FIGS. 2B and 2C, the rotational radius of the air passage 31 is from the axially central portion 35 of the air passage 31 (small diameter end portion 28b) to the joint outer end portion 33 and It gradually expands toward the joint inner end 34. At this time, the centrifugal force acting on the air passage 31 is decomposed into an outer radial direction component and a component along the air passage 31, and the component along the air passage 31 ends from the axial central portion 35. The size gradually increases toward the portions 33 and 34.

  Therefore, during rotation of the joint, in the air passage 31 (inclined portion 31a), the region inside the joint with respect to the axial central portion 35 has a joint internal direction (in FIG. 2C) along the inclined portion 31a. While a force directed in the direction of the arrow C acts, in the region of the ventilation path 31 on the outer side of the joint with respect to the axial center portion 35, the joint outer direction (in FIG. 2C) is formed along the inclined portion 31a. Force in the direction of arrow D). As a result, the lubricant receives a force in the direction of returning to the inside of the joint along the inclined portion 31a due to the centrifugal force, while the foreign substance applies a force in the direction of being discharged to the outside of the joint along the inclined portion 31a by the centrifugal force. receive. Therefore, leakage of the lubricant and entry of foreign matter can be effectively suppressed.

  In addition, since the inside and outside of the joint are always communicated by the air passage 31, the pressure inside and outside the joint can be balanced, and the situation in which the boot 28 is deformed due to the expansion of the internal pressure due to heat generation during rotation is effectively prevented. . From the above, the durability and reliability of the constant velocity universal joint can be improved.

  In the above description, the case where the air passage 31 is configured only by the inclined portion 31a has been described. However, the air passage 31 is not limited to the above-described form, and other forms are possible, and FIG. An example is shown. 3A is different from the configuration shown in FIG. 2A in that the air passage 31 has an angle with respect to the axial direction O and extends in a straight line, and communicates with the inclined portion. And a straight portion extending linearly along the axial direction O. Specifically, as shown in FIGS. 3B and 3C, first and second inclined portions 31b and 31c are provided at both ends of the straight portion 31d. In addition, the point which the whole ventilation path 31 is provided so that the small diameter edge part 28b of the boot 28 may be penetrated in the plane P parallel to an axis line is the same as what is shown in FIG.

  In the case of such a configuration, as in the configuration shown in FIG. 2, a force directed toward the outer side of the joint (in the direction of arrow D in the figure) acts on the first inclined portion 31b due to the centrifugal force when the joint rotates. A force toward the inner side of the joint (in the direction of arrow C in the figure) acts on the two inclined portions 31c. Further, since the rotation radius of the straight portion 31d does not change over the entire length thereof, a force directed toward the end portion of the air passage 31 does not act on the straight portion 31d even by a centrifugal force when the joint rotates. Therefore, the leakage of the lubricant and the entry of foreign matter can be stopped by the straight portion 31d.

  In particular, in the present embodiment, since the straight portion 31d is provided between the first inclined portion 31b and the second inclined portion 31c, the lubricant passes from the second inclined portion 31c to the first over the straight portion 31d. It is difficult to shift to the inclined portion 31b, and similarly, it is difficult for foreign matter to move from the first inclined portion 31b to the second inclined portion 31c. Therefore, both the leakage of the lubricant and the intrusion of foreign matters can be more effectively suppressed.

  In the illustrated example, the first inclined portion 31b and the second inclined portion 31c have the same angle (inclined angle) and length with respect to the axial direction O, but the inclined angles and lengths of both the inclined portions 31b and 31c are mutually different. It is also possible to make them different. For example, when it is desired to give superiority to the effect of preventing the leakage of the lubricant, the formation position of the straight portion 31d is slid toward the joint outer end portion 33 side, and the angle of the second inclined portion 31c with respect to the axial direction O is set to the first What is necessary is just to form at an acute angle rather than that of the inclination part 31b.

  Furthermore, as shown in FIG. 4, one or a plurality of protrusions 32 (two in the illustrated example) that protrude toward the inside of the air passage 31 may be provided. By providing the protruding portion 32, a part of the air passage 31 is narrowed, and the labyrinth seal is configured by the portion, so that both the leakage of the lubricant and the entry of the foreign material can be more reliably suppressed. In particular, it is desirable to provide the protruding portion 32 on the straight portion 31d as in the illustrated example because the above-described effect can be obtained more significantly with the straight portion 31d as a boundary.

  In the above description, the air passage 31 is formed by the single inclined portion 31a, or formed by the first inclined portion 31b, the second inclined portion 31c, and the straight portion 31d, but can be processed. As long as it exists, the inclined part and the straight part 31d can be arbitrarily combined.

  Moreover, although the case where the one ventilation path 31 was provided was demonstrated above, it is also possible to provide multiple (two or more) ventilation paths 31 (illustration is abbreviate | omitted). By adopting such a configuration, it is possible to more effectively prevent the boot 28 from being more effectively prevented from being secured. In addition, when providing the several ventilation path 31, it is desirable to distribute the ventilation path 31 equally in the circumferential direction from a viewpoint of ensuring favorable air permeability.

  FIG. 5 shows another embodiment of the sliding type constant velocity universal joint to which the present invention can be applied. 1 is different from the constant velocity universal joint shown in FIG. 1 in that the outer ring 22 is formed in a bottomed cylindrical shape and the end cap 27 shown in FIG. 1 is omitted. . Also in this embodiment, it goes without saying that the air passage 31 can be configured as shown in FIGS. Since other configurations are the same as those shown in FIG. 1, common reference numerals are assigned and duplicate descriptions are omitted.

  The present invention can be applied not only to the above-described sliding type constant velocity universal joints but also to fixed type constant velocity universal joints, and in particular, the constant velocity universals used for propeller shafts. It is preferably applicable to a joint.

  The present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can of course be implemented in various forms without departing from the gist of the present invention. It is. The scope of the present invention is defined by the terms of the claims, and includes the equivalent meanings recited in the claims and all modifications within the scope.

It is sectional drawing which shows 1st Embodiment of the constant velocity universal joint which concerns on this invention. (A) The figure is the X section expanded sectional view of Drawing 1, (B) figure is a figure which looked at (A) figure from A direction, and (C) figure is a BB sectional view of (B) figure. FIG. 2A shows another configuration of the air passage, wherein FIG. 1A is an enlarged cross-sectional view showing another example of the portion X in FIG. 1, FIG. 2B is a view of FIG. C) The figure is a BB sectional view of (B) figure. It shows another configuration of the air passage, and shows another example of the X part in FIG. It is sectional drawing which shows other embodiment of the constant velocity universal joint which can apply this invention. It is sectional drawing which shows the constant velocity universal joint of a conventional structure.

Explanation of symbols

21 Inner ring 22 Outer ring 23 Ball 24 Cage 25 Stub shaft (shaft member)
28b Small-diameter end portion 30 Boot band 31 Ventilation path 31a Inclined portion 31b First inclined portion 31c Second inclined portion 31d Straight portion 32 Projecting portion O Axial direction P A plane parallel to the axis (virtual plane)

Claims (7)

An outer joint member and an inner joint member that move relative to each other via a torque transmission member, and an end portion is fitted on an outer peripheral surface of a shaft member that is provided between the outer joint member and the inner joint member and extends from the inner joint member. A constant velocity universal joint that includes a boot that seals the inside of the joint, and that can communicate between the inside and outside of the joint through an axial air passage provided at the end of the boot;
The air passage is formed so as to penetrate the end of the boot inside and outside the joint in a plane parallel to the axis, and has an inclined portion that forms an angle with respect to the axial direction. .   The constant velocity universal joint according to claim 1, wherein the ventilation path further includes a straight portion that communicates with the inclined portion and extends in the axial direction.   The constant velocity universal joint according to claim 2, wherein inclined portions are provided at both ends of the straight portion.   The constant velocity universal joint according to claim 1, wherein a plurality of the air passages are provided.   The constant velocity universal joint according to claim 1, further comprising a protruding portion protruding into the air passage.   The constant velocity universal joint according to claim 1, wherein the boot is formed of rubber or a thermoplastic elastomer.   The constant velocity universal joint according to claim 1, wherein the constant velocity universal joint is used for a propeller shaft.

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