JP2006308075A - Constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a constant velocity universal joint for developing highly precise sealing function while preventing the flow of lubricant (grease) from the inside to the outside of the joint. <P>SOLUTION: The constant velocity universal joint comprises a boot 32 having a small end portion 32b to be fitted to a shaft outer peripheral face 28a connected to an inner ring 21. A peripheral recessed groove 37 is provided in the shaft outer peripheral face 28a inside of the joint beyond a fitted site of the small end portion 32b. At the small end portion 32b of the boot 32 inside of the joint, a lip portion 38 is formed which abuts an inner face 37a of the peripheral recessed groove 37 of a shaft 28. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint, and more particularly to a constant velocity universal joint used for a propeller shaft that transmits rotational driving force from a transmission to a differential in 4WD vehicles, FR vehicles, and the like, and a boot for sealing the inside of the joint. It relates to the improved one.

  For example, an FR vehicle has an engine, a clutch, a transmission (transmission) at the front, a reduction gear device (differential), and a drive axle at the rear. Therefore, it is common to use a propeller shaft for power transmission therebetween. . Further, the FR-based 4WD vehicle requires a rear propeller shaft and a front propeller shaft. These propeller shafts are provided with constant velocity universal joints to cope with changes in length and angle due to a relative position change between the transmission and a differential (hereinafter simply referred to as a differential).

  In general, a propeller shaft employs a sliding type constant velocity universal joint called a rebro type (or cross groove type) that is light in weight and has good rotational balance and vibration characteristics from the viewpoint of reducing the weight of the entire vehicle. . This Lebro type constant velocity universal joint has a structure capable of absorbing the axial displacement between the transmission and the differential due to the axial impact at the time of collision.

  FIG. 10A shows an example of a Lebro type constant velocity universal joint 1, and the constant velocity universal joint 1 includes an inner ring 2, an outer ring 3, a ball 4 and a cage 5 as main components. The inner ring 2 has a plurality of track grooves 2a formed on the outer peripheral surface thereof. The shaft portion 8a of the stub shaft 8 is fitted into the hole formed in the center portion of the inner ring 2, and serrations 10 and 11 formed on the inner peripheral surface of the hole of the inner ring 2 and the outer peripheral surface of the shaft portion 8a of the stub shaft 8 are formed. Torque is transmitted by fitting. A ring groove 8b is formed at the axial end of the stub shaft 8, and the stub shaft 8 is positioned and fixed in the axial direction on the inner ring 2 by a snap ring 12 attached to the ring groove 8b.

  The outer ring 3 is located on the outer periphery of the inner ring 2, and the same number of track grooves 3a as the track grooves 2a of the inner ring 2 are formed on the inner peripheral surface. As shown in FIG. 11, the track groove 2a of the inner ring 2 and the track groove 3a of the outer ring 3 form an angle α in the opposite direction with respect to the axis. A ball 4 is incorporated at the intersection of the track groove 2a of the inner ring 2 and the track groove 3a of the outer ring 3 which form a pair. A cage 5 is disposed between the inner ring 2 and the outer ring 3, and the ball 4 is held in a pocket of the cage 5. An annular groove 3b is formed on the inner periphery of the outer ring 3 on the opening side, and the ball 4 is prevented from escaping by a snap ring 17 attached to the annular groove 3b.

  A rubber boot 13 as a sealing device is mounted between the outer ring 3 and the stub shaft 8. The boot 13 encloses a lubricant inside the joint and prevents entry of external dust and muddy water. The boot 13 has a cylindrical shape having a large end portion 13a and a small end portion 13b, and is folded in a U shape in the middle. From the large end portion 13a of the boot 13 to the beginning of the U-shaped fold-back, a reinforcing plate 14 that prevents expansion deformation in the radial direction of the boot 13 is integrally fixed by embedding. The large end portion 13 a of the boot 13 is fastened by the boot band 15 to the annular recess 3 c on the outer peripheral surface of the outer ring 3. A small end portion 13 b of the boot 13 is fastened by a boot band 16 to an annular recess 8 c on the outer peripheral surface of the stub shaft 8. As shown in an enlarged view in FIG. 10B, the small end portion 13b of the boot 13 is formed to be slightly thick so as to be fitted into the annular recess 8c.

Although not shown, a communication passage that balances the internal and external pressures may be formed on the inner diameter surface of the small end portion 13 b of the boot 13 in order to prevent expansion and contraction due to fluctuations in the internal pressure of the boot 13. However, if there is this communication path, it is necessary to take measures to prevent leakage of internal lubricant and external dust, muddy water, etc. The necessity of forming a stop part integrally arises (refer patent document 1).
JP 2001-280513 A

  The dam part disclosed in Patent Document 1 has air passages at a plurality of locations on its inner peripheral edge, and the sealing performance inside the boot ultimately depends on the fastening part of the boot band. However, there are various types of boot bands such as one-touch type, Ω type, low profile band, welding band, etc. All bands have caulking parts such as folds and overlapping parts of the bands. It is difficult to tighten the boots uniformly. For this reason, the sealing performance of the tightening portion of the boot band is difficult to achieve completely, and depending on the tightening state of the boot band, sufficient sealing performance cannot be maintained, and between the boot large end portion 13a and the outer ring 3, or There was a possibility that the lubricant leaked from between the boot small end portion 13b and the stub shaft 8 although it was a small amount.

  This invention solves the said subject, and it aims at improving especially the sealing performance of the boot small end part side.

  In order to solve the above problems, the invention of claim 1 is directed to a cup-shaped outer ring formed with a plurality of linear track grooves extending in the axial direction on a cylindrical inner peripheral surface, and a plurality of straight lines opposed to the track grooves of the outer ring. An inner ring in which a cylindrical track groove is formed on a convex spherical outer peripheral surface and one end of a stub shaft is connected to an inner diameter hole, a plurality of balls that are interposed between the track grooves of the inner and outer rings and transmit the torque, and hold the balls And the cage housed in the annular space between the inner and outer rings, and the large end portion is fitted to the outer circumferential surface of the outer ring and the small end portion is fitted to the outer circumferential surface of the stub shaft, thereby In the constant velocity universal joint provided with a boot for sealing, a lip portion that contacts the outer peripheral surface of the stub shaft is formed on the inner peripheral surface of the small end portion of the boot.

  In this way, a lip portion is added to the inner peripheral surface of the small end of the boot, and the stub shaft and the lip interfere with each other, thereby suppressing the flow of the lubricant to the small end side and lubricant leakage from the small end. Suppress.

The invention of claim 2 is characterized in that, in the invention of claim 1, a notch for ventilation is formed at the tip of the lip portion.
In the constant velocity universal joint, particularly when attached to the propeller shaft, the internal lubricant is unevenly distributed radially outward due to the high speed rotation of the joint. Therefore, the lubricant hardly collects in the vicinity of the stub shaft, and the leakage of the lubricant is prevented, and at the same time, the internal and external pressures can be balanced through the ventilation notch at the tip of the lip portion. In this case, an air passage is formed on the inner diameter surface of the boot small end.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a concave portion for fitting the small end portion of the boot is formed on the outer peripheral surface of the stub shaft, and the lip portion is a stub shaft adjacent to the concave portion. It was made to contact | abut to the outer peripheral surface of this.
By forming the lip part near the small end part, it is possible to indirectly apply the tightening force of the boot band to the lip part, particularly in the axial deformation of the boot in the sliding type constant velocity universal joint. Nevertheless, the contact of the lip portion with the stub shaft is ensured.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, a plurality of lip portions that are in contact with the outer peripheral surface of the shaft closer to the inner side of the joint than the fitting portion of the small end portion are axially provided on the inner side of the joint of the boot It is characterized by being formed along.
A plurality of seal structures can be configured. For this reason, it is possible to improve the function of preventing the lubricant from flowing to the small end side.

According to a fifth aspect of the present invention, an outer ring having a plurality of linear track grooves extending in the axial direction on the inner peripheral surface, a plurality of linear track grooves facing the track grooves of the outer ring are formed on the outer peripheral surface, and an inner diameter hole is formed. An inner ring with one end of the stub shaft connected thereto, a plurality of balls that are interposed between the track grooves of the inner and outer rings, and a torque that is held between the inner and outer rings, and is accommodated in an annular space between the inner and outer rings. In a constant velocity universal joint including a cage and a boot having a small end fitted to the outer peripheral surface of the stub shaft, a circumferential concave groove is formed on the outer peripheral surface of the shaft on the inner side of the joint with respect to the fitting portion of the small end. And a lip portion that contacts the inner surface of the circumferential groove of the shaft is formed on the inner side of the joint of the boot.
The flow of the lubricant to the small end portion side can be more stably suppressed by the boot side lip portion and the shaft side circumferential groove.

According to a sixth aspect of the present invention, in the fifth aspect, a plurality of lip portions are formed along the axial direction on the inner side of the joint of the boot so as to contact the outer peripheral surface of the shaft on the inner side of the joint with respect to the fitting portion of the small end. At least one lip portion is in contact with the inner surface of the circumferential groove.
In addition to the plurality of seal structures, the lip portion comes into contact with the inner surface of the circumferential groove, so that it is possible to further improve the function of preventing the lubricant from flowing to the small end side.

The invention according to claim 7 is the invention according to claims 1 to 6, wherein the constant velocity universal joint is of a sliding type.
Since the sliding type constant velocity universal joint has internal and external pressure fluctuations due to the axial deformation of the boot, there is a high possibility that the lubricant leaks compared to the fixed type constant velocity universal joint. In this case, leakage of the lubricant can be effectively prevented by the lip portion.

  The constant velocity universal joint of the present invention includes a fixed type and a sliding type. The fixed type includes a Rzeppa type constant velocity universal joint, and the sliding type includes a Lebro type constant velocity universal joint, a double offset type constant velocity universal joint, and a tripod type constant velocity universal joint.

  In the present invention, since a lip portion that interferes with the stub shaft is added to the inside of the joint at the small end portion of the boot, the flow of the lubricant to the small end portion side is suppressed, and the lubricant leakage from the small end portion is suppressed. be able to. Thereby, even if the tightening force of the boot band is not uniform in the circumferential direction, it is possible to prevent lubricant leakage.

Particularly, in the sliding type constant velocity universal joint, the internal lubricant is likely to be pushed out by the internal pressure fluctuation or the lubricant movement due to the sliding, but the effect of preventing the lubricant leakage is enhanced by applying the present invention. In addition, when used at a high speed, such as a constant velocity universal joint for a propeller shaft, the lubricant enclosed in the joint is easily softened, and the lubricant is more likely to leak, but the present invention is applied. By doing so, the lubricant leakage preventing effect is remarkably increased. In addition, when the lubricant is softened due to change with time, deterioration, or the like, or with a lubricant such as gear oil, a particularly remarkable effect is obtained.

  In addition, a circumferential groove is provided on the outer peripheral surface of the shaft on the inner side of the joint with respect to the fitting portion of the small end portion, and a lip portion is brought into contact with the inner surface of the circumferential groove, The flow of the lubricant to the small end side can be more stably suppressed. As a result, it is possible to improve the sealing performance and prevent the constant velocity universal joint from deteriorating due to lubricant leakage, and the constant velocity universal joint can exhibit a stable function over a long period of time.

  Further, in the case where a plurality of lip portions are formed, a plurality of seal structures can be formed, so that the function of preventing the lubricant from flowing to the small end side can be improved. For this reason, the improvement of a sealing performance can be aimed at and the functional fall of the constant velocity universal joint by lubricant leakage can be prevented.

  In the case where a plurality of lip portions are formed, if a circumferential groove is provided on the outer peripheral surface of the shaft, and at least one lip portion is brought into contact with the inner surface of the circumferential groove, the small end side of the lubricant It is possible to further improve the flow prevention function.

  Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. The constant velocity universal joint 1 in FIG. 1A is the same as the conventional Lebro type constant velocity universal joint (non-float type) except for the lip portion 13c of the boot 13 as a sealing device. ), Which is mounted on the propeller shaft of an automobile. The boot 13 is made of a flexible material such as a rubber material or a resin material, and includes a large end portion 13 a fixed to the outer ring 3 of the constant velocity universal joint 1 and a small end portion 13 b fixed to the stub shaft 8. It has a cylindrical shape. The middle part between the large end part 13a and the small end part 13b is shaped like a U-shape.

  Hereinafter, the details of the boot 13 will be described. An annular recess 3c is formed on the outer peripheral surface of the outer ring 3 of the constant velocity universal joint 1, and can be fitted into the recess 3c on the inner peripheral side of the large end portion 13a of the boot 13. A thick portion having a convex cross section is formed. The large end portion 13a has a natural inner diameter slightly smaller than the outer diameter of the concave portion 3c in order to secure the fitting property to the concave portion 3c. The large end portion 13a is fastened to the recess 3c by a boot band 15 attached to the outer periphery thereof.

  On the other hand, an annular recess 8 c is formed on the outer peripheral surface of the stub shaft 8, and a thick section having a convex cross section that can be fitted into the recess 8 c is formed on the inner peripheral side of the small end portion 13 b of the boot 13. The small end portion 13b secures the fitting property of the stub shaft 8 to the concave portion 8c, so that its natural inner diameter is slightly smaller than the outer diameter of the concave portion 8c. The small end portion 13b is fastened to the concave portion 8c by a boot band 16 attached to the outer periphery thereof.

  From the large end portion 13a of the boot 13 to the beginning of the U-shaped folding, a reinforcing plate 14 for preventing the boot 13 from expanding in the radial direction is integrated by embedding. The reinforcing plate 14 is formed of a material having higher rigidity than the material for forming the boot 13, and preferably a steel plate is used. The reinforcing plate 14 is bent in an L shape at a portion embedded in the boot large end portion 13a. By embedding the reinforcing plate 14 in the boot 13, the rigidity of the boot 13 is increased and the reinforcing plate 14 is covered to prevent the generation of rust. In addition, in order to make the boot small end part 13b follow the stub shaft 8 easily at the time of the joint rotation, the U-shaped folded part is formed slightly thin and has appropriate elasticity.

  A lip portion 13c having a substantially triangular cross section in the natural state is integrally formed on the inner peripheral surface immediately inside the small end portion 13b of the boot 13 as shown in an enlarged view in FIG. When the stub shaft 8 is inserted from the outside into the small end portion 13b, the lip portion 13c is pushed inward by friction with the outer peripheral surface of the stub shaft 8, as shown in FIG. 8 is a flat shape along the outer peripheral surface. Therefore, the tip of the lip portion 13c is in contact with the outer peripheral surface of the stub shaft 8 substantially in a sharpened state. A ventilation notch can be formed at the tip of the lip portion as needed. If the number of notches is not large and the number is within an appropriate range, there is almost no effect on prevention of lubricant leakage.

  The constant velocity universal joint according to the present invention is configured as described above. After the stub shaft 8 is fitted and inserted into the small end portion 13b of the boot 13, the small end portion 13b is fastened to the annular recess 8c with the boot band 16. The lip portion 13c is indirectly pressed against the outer peripheral surface of the stub shaft 8 by the force. Thus, by forming the lip portion 13c near the small end portion 13b, the tightening force of the boot band 16 can be indirectly applied to the lip portion 13c, and in particular, a sliding type constant velocity universal joint. However, the contact of the lip portion 13c with the stub shaft 8 is ensured despite the axial deformation of the boot.

  In this way, the lip portion 13c provided in the boot 13 interferes with the stub shaft 8, thereby preventing the lubricant enclosed inside from flowing into the small end portion 13b. This makes it possible to prevent lubricant leakage even when the tightening force of the boot band 16 is uneven in the circumferential direction. In particular, the sliding type constant velocity universal joint is more likely to push out the internal lubricant than the fixed type due to fluctuations in internal pressure due to sliding of the inner ring or movement of the lubricant, but applying the present invention increases the effect of preventing lubricant leakage. In addition, when used at a high speed, such as a constant velocity universal joint for a propeller shaft, the lubricant enclosed in the joint is easily softened, and the lubricant is more likely to leak, but the present invention is applied. By doing so, the lubricant leakage preventing effect is remarkably increased. In addition, when the lubricant is softened due to change with time, deterioration, or the like, or with a lubricant such as gear oil, a particularly remarkable effect is obtained.

As a second embodiment of the present invention, a float type Lebro type constant velocity universal joint is shown in FIG. The constant velocity universal joint in the second embodiment includes an inner ring 21, an outer ring 22, a ball 23, and a cage 24 as main components.

  The inner ring 21 has a plurality of track grooves 26 formed on its outer peripheral surface (convex spherical outer peripheral surface). A stub shaft 28 is inserted into the center hole (inner diameter hole) 25 of the inner ring 21 and is spline-fitted, and torque can be transmitted between the two by the spline fitting. The stub shaft 28 is prevented from coming off from the inner ring 21 by a snap ring 31.

  The outer ring 22 is located on the outer periphery of the inner ring 21, and the same number of track grooves 27 as the track grooves 26 of the inner ring 21 are formed on the inner peripheral surface (cylindrical inner peripheral surface) thereof. The track groove 26 of the inner ring 21 and the track groove 27 of the outer ring 22 form an angle (track crossing angle) inclined in the opposite direction with respect to the axis, and the pair of the track groove 26 of the inner ring 21 and the track groove 27 of the outer ring 22 A ball 23 is incorporated in the crossing portion. A cage 24 is disposed between the inner ring 21 and the outer ring 22, and the ball 23 is held in a pocket 29 of the cage 24.

  On one end side in the axial direction of the outer ring 22, an end cap 30 for preventing leakage of grease filled in the joint and preventing entry of foreign matter is fixed by bolting, and the outer ring 22 and the stub on the other end side in the axial direction are fixed. A sealing device is mounted between the shaft 28.

This sealing device includes a boot 32 and a metal boot adapter 33. The boot 32 is made of a flexible material such as a rubber material or a resin material, and has a V-shaped cross section that connects the large end 32a, the small end 32b, and the large end 32a and the small end 32b. Intermediate portion 32c. The boot adapter 33 has a cylindrical shape, has a flange 33a fitted to the outer peripheral surface of the outer ring 22 at one end, and is fixed to the outer ring 22 together with the end cap 30 by bolting. A small end portion 32 b of the boot 32 is attached to the stub shaft 28 and fastened by a boot band 34. The large end portion 32 a of the boot 32 is held by crimping the end portion 33 b of the boot adapter 33.

An annular recess 35 is formed in the outer peripheral surface 28 a of the shaft 28, and a small end portion 32 b of the boot 32 is fitted on the annular recess 35 and fastened with a boot band 34. The small end portion 32b is formed of a thick cylindrical portion, and its inner diameter is slightly smaller than the outer diameter of the annular recess 35 in a free state, thereby securing the fitting property to the annular recess 35. Further, a circumferential groove 36 having a concavo-convex portion on the bottom surface is formed on the outer peripheral surface of the small end portion 32b, and the boot band 34 is fitted in the circumferential groove 36.

A circumferential groove 37 is provided on the outer peripheral surface 28a of the joint on the inner side of the joint relative to the fitting portion of the small end portion 32b, and a lip portion that contacts the inner surface 37a of the circumferential groove 37 on the inner side of the joint of the boot 32. 38 is formed. Here, the fitting part of the small end portion 32b is a fastening part of the boot band 34 and means a part corresponding to the boot band 34.

As shown in FIG. 3, the inner surface 37 a of the circumferential groove 37 includes a bottom surface 40 having a smaller diameter than the shaft outer peripheral surface 28 a and tapered portions 41, 42 connected to both axial ends of the bottom surface 40. The taper portion 41 on the shaft spline side gradually increases in diameter from the bottom surface 40 toward the shaft spline side, and the taper portion 42 on the annular recess 35 side sequentially increases in diameter from the bottom surface 40 toward the annular recess 35. Between the circumferential groove 37 and the annular recess 35, there is provided a non-groove forming portion 43 having a predetermined short dimension in the axial direction whose outer diameter is the outer diameter of the shaft outer peripheral surface 28a.

The lip portion 38 projects from the inside of the joint to the inner diameter side with respect to the small end portion 32b. In the case of FIG. 3, the lip portion 38 has a substantially triangular cross section in a free state, and the inner peripheral edge portion 44 abuts against the tapered portion 41 from the small end portion 32b side in the mounted state. That is, the lip portion 38 is curved toward the anti-small diameter portion.

  After the stub shaft 28 is fitted and inserted into the small end portion 32b of the boot 32, the small end portion 32b is fastened to the annular recess 35 by the boot band 34, and this fastening force causes the fitting portion of the small end portion 32b and the lip portion 38 to be fitted. The portion between the lip portion 38 and the lip portion 38 is indirectly pressed against the inner surface 37a of the circumferential groove 37 of the stub shaft 8. Thus, by forming the lip portion 38 near the small end portion 32b, the tightening force of the boot band 34 can be indirectly applied to the lip portion 38 as well.

  In FIG. 4, the inner peripheral edge 44 abuts against the tapered portion 42 from the opposite end side in the mounted state, and in FIG. 5, the inner peripheral edge 44 contacts the bottom surface 40 from the outer diameter side in the mounted state. .

  As shown in FIGS. 3 to 5, when the lip portion 38 is brought into contact with the inner surface 37 a of the circumferential groove 37, the lip portion 38 provided on the boot 32 interferes with the stub shaft 8. Thus, the lubricant enclosed inside is prevented from flowing to the small end portion 32b. Thereby, even if the tightening force of the boot band 36 is not uniform in the circumferential direction, it is possible to prevent the lubricant from leaking.

  In addition, since the lip portion 38 is brought into contact with the inner surface 37a of the circumferential groove 37 of the shaft 28, the flow of the lubricant toward the small end portion can be more stably suppressed by the circumferential groove 37. As a result, it is possible to improve the sealing performance and prevent the constant velocity universal joint from deteriorating due to lubricant leakage, and the constant velocity universal joint can exhibit a stable function over a long period of time.

  Next, FIG. 6 shows a third embodiment. In this case, a plurality (in the illustrated example) abuts the shaft outer peripheral surface 28a on the joint inner side of the small end portion 32b on the joint inner side of the boot 32. Two) lip portions 38a, 38b are formed along the axial direction.

  In this case, although the circumferential groove 37 is not formed in the shaft 28, a small diameter portion 45 having an outer diameter substantially the same diameter as the bottom surface of the annular recess 35 is formed between the shaft spline and the annular recess 35. In addition, a non-groove forming portion 43 is formed between the small diameter portion 45 and the annular recess 35 via a taper portion 46.

  Therefore, the inner peripheral edge 44a of the lip portion 38a on the small end portion 32b side abuts on the tapered portion 46 from the outer diameter side, and the inner peripheral edge portion 44b of the lip portion 38b on the opposite small end portion side has a small end on the small diameter portion 45. It abuts from the part 32b side. In FIG. 7, the inner peripheral edge 44 b of the lip portion 38 b on the anti-small end side is in contact with the small diameter portion 45 from the anti-small end side. The constant velocity universal joint shown in FIGS. 6 and 7 shows only the small end portion 32b of the boot 32 and its vicinity, but the other configuration is the same as that of the second embodiment shown in FIG. Therefore, the illustration is omitted.

  6 and 7, a plurality of lip portions 38a and 38b that are in contact with the shaft outer peripheral surface 28a on the inner side of the joint with respect to the fitting portion of the small end portion 32b are formed along the axial direction. Thereby, a multiple (double) seal structure can be comprised.

  Therefore, as shown in FIGS. 6 and 7, even if the lip portions 38a and 38b are formed along the axial direction, the circumferential groove 37 allows the lubricant to flow toward the small end side. It can suppress more stably and can show the effect similar to the constant velocity universal joint shown in FIG.

Next, FIG. 8 shows a fourth embodiment. In this case, the constant velocity universal joint of FIG. 2 and the constant velocity universal joint of FIG. 6 are combined. That is, a circumferential groove 37 is formed in the shaft 28, and a plurality of lip portions 38 a and 38 b are formed in the boot 32.

The inner peripheral edge portion 44a of the lip portion 38a on the small end portion 32b side abuts against the tapered portion 42 of the circumferential groove 37 from the side opposite to the small end portion, and the inner peripheral edge portion 44b of the lip portion 38b on the anti-small end portion side is The shaft is in contact with the shaft outer peripheral surface 28a on the inner side of the joint with respect to the circumferential groove 37 from the circumferential groove 37 side.

In FIG. 9, the inner peripheral edge 44a of the lip portion 38a on the small end portion 32b side abuts against the bottom surface 40 of the circumferential groove 37 from the outer diameter side, and the inner peripheral edge portion 44b of the lip portion 38b on the opposite small end portion side. The outer peripheral surface abuts against the shaft outer peripheral surface 28a on the inner side of the joint with respect to the circumferential groove 37 from the outer diameter side. The constant velocity universal joint shown in FIGS. 8 and 9 shows only the small end portion 32b of the boot 32 and its vicinity, but the other configuration is the same as that of the second embodiment shown in FIG. Therefore, the illustration is omitted.

8 and 9, in addition to the multiple (double) seal structure, at least one lip portion 38a comes into contact with the inner surface 37a of the circumferential groove 37. For this reason, in the constant velocity universal joint shown in FIGS. 8 and 9, the function of preventing the flow of the lubricant to the small end side can be further improved.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications can be made. For example, the present invention can be applied to a sliding type constant velocity universal joint other than the Lebro type. The present invention can be applied to a fixed type constant velocity universal joint. That is, as the constant velocity universal joint, various types such as a fixed constant velocity universal joint such as a Rzeppa type and a barfield type, and a sliding type constant velocity universal joint such as a double offset type and a tripod type can be used. . Further, the present invention can be applied not only to an automobile propeller shaft but also to a constant velocity universal joint for a drive shaft and further for a general industrial machine.

  The depth dimension and the axial length of the circumferential concave groove 37 differ depending on the shape and size of the lip portion 38, but as shown in FIG. The inner peripheral edge 44 of 38 can be changed in a range where it abuts against the inner surface 37 a of the circumferential groove 37. Further, the circumferential concave groove 37 may not have the taper portions 41 and 42. 3 to 5, the taper portion 42 has a larger inclination angle than the taper portion 41. However, the taper portion 41 and the taper portion 42 may have the same inclination angle. Conversely, the taper portion 41 is tapered. The inclination angle may be larger than that of the portion 42.

  When the inner peripheral edge 44 of the lip portion 38 abuts against the inner surface 37a of the circumferential groove 37, for example, the inner peripheral edge 44 is formed on the bottom surface 40 from the small end 32b side in addition to those shown in FIGS. Or you may contact | abut from the non-small edge part side. Further, when the two lip portions 38 a and 38 b are provided, the two lip portions 38 a and 38 b may be brought into contact with the inner surface 37 a of the circumferential groove 37.

The number of lip portions 38 is not limited to one or two, and may be three or more. Furthermore, the cross-sectional shape of the lip portion 38 is not limited to a triangle, and may be other shapes such as a trapezoidal shape. When a plurality of lip portions 38 are provided, the small diameter portion 45 as shown in FIGS. 6 and 7 may not be provided.

You may provide the notch for ventilation | gas_flowing in the front-end | tip (inner peripheral part) of the lip | rip part 38 as needed. In this case, it is necessary to set the size and number of notches so as not to affect the prevention of lubricant leakage.

As shown in FIG. 1, even in a sealing device without a boot adapter, a circumferential groove 37 is provided in the shaft 28, and the lip portion 13c is brought into contact with the inner surface 37a of the circumferential groove 37. Alternatively, a plurality of lips 13c may be provided. On the contrary, even if it is a sealing device which has the boot adapter 33 as shown in FIG. 2, etc., as shown in FIG. 1, the shaft 28 may not have the circumferential groove 37.

The embodiment of the constant velocity universal joint for propeller shafts concerning this invention is shown, (A) is sectional drawing of a joint, (B) is the natural state of the boot small diameter part in the ellipse shown by the dashed-dotted line of (A). FIG. It is sectional drawing of the constant velocity universal joint which shows 2nd Embodiment of this invention. It is a principal part expanded sectional view of the said constant velocity universal joint. It is a principal part expanded sectional view which shows the other lip | rip part of the said constant velocity universal joint. It is a principal part expanded sectional view which shows another lip part of the said constant velocity universal joint. It is a principal expansion sectional view of the constant velocity universal joint which shows 3rd Embodiment of this invention. FIG. 6 is an enlarged cross-sectional view showing another lip portion of the constant velocity universal joint. It is a cross-sectional view of the constant velocity universal joint showing the fourth embodiment of the present invention. FIG. 6 is an enlarged cross-sectional view showing another lip portion of the constant velocity universal joint. 1 shows a conventional constant velocity universal joint for a propeller shaft, (A) is a sectional view of the joint, and (B) is a sectional view in a natural state of a small diameter portion of a boot in an ellipse indicated by an alternate long and short dash line in (A). . It is a figure which expands and shows an inner ring and an outer ring on a plane.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lebro type constant velocity universal joint 2a Track groove 2 Inner ring 3 Outer ring 3a Track groove 3b Ring groove 3c Ring recess 4 Ball 5 Cage 8 Stub shaft 8a Shaft 8b Ring groove 8c Ring recess 10, 11 Serration 12 Snap ring 13 Boot 13a Boot Large end portion 13b Small boot end portion 13a Large end portion 13b Small end portion 13c Lip portion 14 Reinforcement plate 15 Boot band 16 Boot band 17 Snap ring 21 Inner ring 22 Outer ring 23 Ball 24 Cage 26, 27 Track groove 28 Stub shaft 28a Shaft outer periphery Surface 29 Pocket 30 End cap 31 Snap ring 32 Boot 32c Intermediate part 32a Large end part 32b Small end part 33 Boot adapter 33a Flange 33b End part 34 Boot band 35 Annular recess 36 Circumferential groove 37a Inner surface 37 Circumferential concave groove 38, 38a , 8b lip portion 40 bottom surface 41 periphery 45 small diameter portion 46 tapered section α angle in the tapered portion 42 tapered portion 43 non-groove portion 44 the peripheral portion 44a in the peripheral portion 44b

Claims (7)

A cup-shaped outer ring formed with a plurality of linear track grooves extending in the axial direction on the cylindrical inner peripheral surface, and a plurality of linear track grooves facing the track grooves of the outer ring are formed on the convex spherical outer peripheral surface and an inner diameter hole An inner ring with one end of the stub shaft connected thereto, a plurality of balls that are interposed between the track grooves of the inner and outer rings, and a torque that is held between the inner and outer rings, and is accommodated in an annular space between the inner and outer rings. In a constant velocity universal joint comprising a cage and a boot that seals the inside of the joint by fitting a large end to the outer peripheral surface of the outer ring and a small end to the outer peripheral surface of the stub shaft,
A constant velocity universal joint characterized in that a lip portion that contacts the outer peripheral surface of the stub shaft is formed on the inner peripheral surface of the small end portion of the boot.   2. The constant velocity universal joint according to claim 1, wherein a notch for ventilation is formed at a tip of the lip portion.   2. A recess for fitting a small end portion of the boot is formed on an outer peripheral surface of the stub shaft, and the lip portion is brought into contact with an outer peripheral surface of the stub shaft adjacent to the recess. Or 2 constant velocity universal joints. 4. A plurality of lip portions that are in contact with the outer peripheral surface of the shaft on the inner side of the joint relative to the fitting portion of the small end portion are formed along the axial direction on the inner side of the joint of the boot. One of the constant velocity universal joints. An outer ring formed with a plurality of linear track grooves extending in the axial direction on the inner peripheral surface, and a plurality of linear track grooves opposed to the track grooves of the outer ring are formed on the outer peripheral surface, and one end of the stub shaft is connected to the inner diameter hole An inner ring, a plurality of balls that transmit torque by being interposed between the track grooves of the inner and outer rings, a cage that holds the balls and is accommodated in an annular space between the inner and outer rings, and a small end portion In a constant velocity universal joint provided with a boot fitted on the outer peripheral surface of the stub shaft,
A circumferential groove is provided on the outer peripheral surface of the shaft on the inner side of the joint relative to the fitting portion of the small end portion, and a lip portion is formed on the inner side of the joint of the boot so as to contact the inner surface of the circumferential groove of the shaft. A constant velocity universal joint characterized by A plurality of lip portions that are in contact with the outer peripheral surface of the shaft on the inner side of the joint with respect to the fitting portion of the small end portion are formed along the axial direction on the inner side of the joint of the boot, and at least one lip portion is formed on the peripheral surface. 6. The constant velocity universal joint according to claim 5, wherein the constant velocity universal joint is brought into contact with an inner surface of the directional groove. 7. The constant velocity universal joint according to claim 1, wherein the constant velocity universal joint is a sliding type.

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