JP7382705B2 - Sliding type constant velocity universal joint for propeller shaft - Google Patents

Description

The present invention relates to a sliding constant velocity universal joint exclusively for a propeller shaft.

Sliding constant velocity universal joints that can accommodate axial and angular displacement are used in propeller shafts used in automobiles such as four-wheel drive vehicles (4WD vehicles) and front-engine rear-wheel drive vehicles (FR vehicles). There is. These sliding constant velocity universal joints include double offset type sliding constant velocity universal joints (DOJ), tripod type sliding type constant velocity universal joints (TJ), and cross groove type sliding type constant velocity universal joints (LJ). ) etc. are used.

In recent years, as automobiles have become more fuel efficient, propeller shafts have also been required to be smaller and lighter. Conventionally, in order to standardize the components, each part used for the drive shaft (outer joint member, inner joint member, retainer, etc.) was changed by changing the shape of the attachment part of the outer joint member, and was used for other parts. The parts have been used as is for propeller shafts.

A double offset type sliding constant velocity universal joint (hereinafter also referred to as DOJ) is one of the sliding constant velocity universal joints used in propeller shafts. Patent Document 1 listed below proposes a DOJ with eight balls in order to reduce its size and weight.

Japanese Patent Application Publication No. 10-73129

DOJ can have a relatively large sliding amount in the axial direction, has been used extensively and has stable performance, and can be made smaller and lighter by having eight balls. The present inventors have studied various types of DOJ currently used in propeller shafts in order to meet the demands for further improvement in fuel efficiency of automobiles and for propeller shafts to be smaller, lighter, and rotate at higher speeds.

SUMMARY OF THE INVENTION An object of the present invention is to provide a small, lightweight sliding type constant velocity universal joint exclusively for propeller shafts that can contribute to the demands for further lower fuel consumption in automobiles and higher rotation speeds for propeller shafts.

The present inventors have conducted various studies to achieve the above object, and have arrived at the present invention based on the following findings and ideas.
(1) The current 8-ball type DOJ for propeller shafts shown in Figures 11 and 12 has a maximum operating angle of about 25° so that it can also be used for drive shafts. We focused on the fact that the functions of DOJ can be limited by specializing in the characteristics required for propeller shafts. Specifically, it has been found that by dedicating the DOJ to the propeller shaft, the maximum operating angle can be limited to a low value (for example, 15 degrees or less), and thereby the DOJ can be made smaller and lighter.
(2) By limiting the maximum operating angle of the DOJ dedicated to the propeller shaft to a low value, the following specific technical effects can be obtained.
(a) Compactness and weight reduction in the radial direction by reducing the wall thickness of each component (outer joint member, inner joint member, cage) (b) Axial direction of the inner joint member by reducing the amount of axial movement of the ball (c) Making the cage more compact and lighter in the radial direction by reducing the circumferential movement of the balls (d) Making the cage more compact and lighter in the axial direction by reducing the pocket load (3) ) In addition, we focused on the dynamic factors of the small and nearly constant operating angle of DOJ for propeller shafts and high speed rotation, and investigated the possibility of further weight reduction and compactness. As a result, we came up with the idea of reducing the amount of offset of the cage, and found that this would dramatically promote the technical effect of (2) above, and achieve a lighter weight and more compact design, which is qualitatively different from conventional methods. did.
(4) Furthermore, in terms of performance, we came up with the idea of using both the axial pocket clearance δ1 between the pockets of the cage and the balls and the axial clearance δ2 between the spherical surfaces of the cage and the inner joint member. The advantageous configuration of the present invention was achieved by verifying the effects of improving the life of a dedicated DOJ, increasing rotation speed, reducing sliding resistance, and improving vehicle vibration characteristics.

As a technical means to achieve the above-mentioned object, the present invention provides a sliding constant velocity universal joint for a propeller shaft, in which eight linear track grooves are formed along the axial direction on the cylindrical inner peripheral surface. a connecting hole in which eight linear track grooves facing the linear track grooves of the outer joint member are formed in the axial direction on the outer joint member formed, and a female spline is formed on the spherical outer circumferential surface thereof; an inner joint member having an inner joint member, eight torque transmission balls incorporated between a linear track groove of the outer joint member and a linear track groove of the inner joint member, and the torque transmission balls are accommodated in a pocket. , a cage having a spherical outer circumferential surface that is guided in contact with the cylindrical inner circumferential surface of the outer joint member and a spherical inner circumferential surface that is guided in contact with the spherical outer circumferential surface of the inner joint member, the spherical shape of the cage being Consisting of a double offset type sliding constant velocity universal joint in which the center of curvature of the outer circumferential surface and the center of curvature of the spherical inner circumferential surface have an equal offset amount (f) on the opposite side in the axial direction with respect to the center of the pocket. and the ratio Ti/Db of the wall thickness Ti of the inner joint member and the ball diameter Db of the torque transmission ball is 0.30 or more and 0.45 or less, and the pitch circle diameter PCD _BALL of the torque transmission ball and the It is characterized in that the ratio PCD _BALL /Db to the diameter Db of the torque transmission ball is 3.3 to 3.6.

In a ball-type constant velocity universal joint that transmits torque through balls, when the operating angle is 0°, each ball receives an equal load, but when the operating angle is changed, each ball receives an uneven load, causing The higher the angle, the greater the difference. Therefore, in the case of a high operating angle, the maximum load applied to one ball increases, so the inner joint member, outer joint member, and cage that come into contact with the ball must be able to withstand the load received from the ball. Thick wall thickness is required.

Therefore, by using the DOJ exclusively for the propeller shaft, the maximum operating angle can be limited to a low value, and the maximum load applied to one ball can be reduced. As a result, the load that the inner joint member and the outer joint member receive from the ball is reduced, so that their wall thicknesses can be reduced, and the DOJ can be made more compact and lightweight in the radial direction.

Furthermore, by limiting the maximum operating angle of the DOJ to a low value, the amount of circumferential movement of the balls in the pocket of the retainer becomes small, so the length of the pocket in the circumferential direction can be shortened. This makes it possible to reduce the diameter of the retainer, thereby reducing the pitch circle diameter PCD _BALL of the balls and, in turn, the outer diameter of the outer joint member, making the DOJ more compact in the radial direction and lighter in weight. can be achieved.

In addition, by limiting the maximum operating angle of the DOJ to a low value, the strength of the inner joint member can be increased, so the inner diameter of the connecting hole of the inner joint member to which the shaft is connected, that is, the pitch circle diameter of the female spline, is increased. be able to. This allows the shaft, which is the weakest component at low operating angles, to be strengthened by increasing its diameter, thereby improving the durability of the propeller shaft.

In DOJ, by offsetting the center of curvature of the spherical outer circumferential surface and the center of curvature of the spherical inner circumferential surface of the cage in the axial direction, the balls are held on the bisector of the operating angle at all operating angles. It realizes torque transmission at high speed. The DOJ of the propeller shaft has a small and approximately constant operating angle, so even if the offset amount (f) between the center of curvature of the outer circumferential surface of the retainer and the center of curvature of the inner circumferential surface is small, smooth torque transmission is not possible. It becomes possible. The present inventors have found that by reducing the offset amount (f) of the cage, it is possible to reduce the axial dimension and radial wall thickness of the cage without impairing the function or durability of the DOJ. This led to the realization of an even smaller and lighter DOJ. In addition, by reducing the offset amount (f) of the cage, the force acting on the pockets of the cage and the inner circumferential surface of the outer joint member is reduced, so in DOJ for propeller shafts used at high speeds, The amount of heat generated can be suppressed.

In the above sliding type constant velocity universal joint for a propeller shaft, an axial pocket clearance δ1 is provided between the axial wall surface (an axially opposing surface) of the cage pocket and the torque transmission ball, and the above-mentioned It is desirable to provide an axial clearance δ2 between the spherical inner circumferential surface of the retainer and the spherical outer circumferential surface of the inner joint member. This suppresses the temperature rise caused by sliding between the cage and the balls and between the cage and the inner joint member, which is effective in increasing the life of the joint and increasing rotation speed. Slide resistance is reduced. Further, the pocket clearance δ1 and the axial clearance δ2 described above can absorb vibrations from the engine, thereby improving the vibration characteristics of the vehicle. In particular, it is desirable that the pocket clearance δ1 be 0 to 0.050 mm and the axial clearance δ2 be 0.5 to 1.5 mm.

According to the present invention, it is possible to realize a small and lightweight sliding type constant velocity universal joint exclusively for propeller shafts, which can contribute to the demands for further lower fuel consumption of automobiles and higher rotation speeds of propeller shafts.

1 is a diagram showing a propeller shaft equipped with a sliding type constant velocity universal joint for a propeller shaft according to an embodiment of the present invention. A sliding constant velocity universal joint for a propeller shaft according to an embodiment of the present invention is shown, in which (a) is a vertical cross-sectional view taken along the line BNB in (b); a) A cross-sectional view taken along line AA in the figure. Figure (a) is a comparison of longitudinal sections of the sliding type constant velocity universal joint for a propeller shaft according to this embodiment and the current sliding type constant velocity universal joint used for propeller shafts. The longitudinal section of the upper half of the sliding type constant velocity universal joint shown in Figure 11(a) above the axis NN is shown on the upper side, and It is the figure which reversed the longitudinal section and showed it on the lower side. (b) The figure shows the longitudinal cross-section of the lower half of the sliding type constant velocity universal joint in Figure 2(a) reversed from the axis line N-N on the upper side, and the sliding type constant velocity universal joint in Figure 11(a). FIG. 3 is a diagram showing a vertical cross section of the lower half of the joint from the axis NN on the lower side. Comparison of the axial movement state of the inner joint member and ball of the sliding type constant velocity universal joint (upper half) in Figure 2(a) and the sliding type constant velocity universal joint (lower half) in Figure 11(a) FIG. FIG. 3 is an enlarged vertical cross-sectional view of the inner joint member, retainer, and ball of FIG. 2(a). (a) is an enlarged view of section C in FIG. 5, and (b) is an enlarged view of section D in FIG. 5. (a) is a longitudinal cross-sectional view showing an inner joint member, a retainer, and a ball of standard specifications in which pocket clearance δ1 and axial clearance δ2 are not provided. (b) is a longitudinal cross-sectional view showing the inner joint member, retainer, and balls with specifications in which a pocket clearance δ1 and an axial clearance δ2 are provided. (c) is a longitudinal sectional view showing an inner joint member, a retainer, and a ball of another specification in which a pocket clearance δ1 and an axial clearance δ2 are provided. FIG. 3 is a longitudinal cross-sectional view showing the maximum operating angle of the sliding constant velocity universal joint in FIG. 2; FIG. 3 is a longitudinal sectional view showing the operating angle of the sliding constant velocity universal joint shown in FIG. 2 when the boot is attached. It is a diagram comparing the cross section of the sliding type constant velocity universal joint in FIG. 2(b) with the cross section of the sliding type constant velocity universal joint in FIG. 11(b). The current sliding type constant velocity universal joint is shown, and (a) is a vertical cross-sectional view taken along the line FNF in (b), and (b) is a vertical cross-sectional view taken along the line EE in (a). FIG. FIG. 12 is a longitudinal sectional view showing an assembled state of the sliding constant velocity universal joint of FIG. 11. 1 is a plan view showing an outline of a drive system of an FF-based 4WD vehicle. FIG. 2 is a plan view showing an outline of a drive system of an FR-based 4WD vehicle.

Embodiments of the present invention will be described based on the drawings.

First, an outline of a drive system will be explained based on FIGS. 13 and 14 using a four-wheel drive vehicle (hereinafter also referred to as a 4WD vehicle) using a propeller shaft as an example.

As shown in Figure 13, the drive system of a 4WD vehicle based on FF (front engine front wheel drive) is engine 100 → transaxle 113 → differential 111 → transfer 112 → propeller shaft (rear propeller shaft) 102 → differential 103 → drive shaft The driving force is transmitted from 104 to the rear wheels 105. Further, on the front side, driving force is transmitted from the engine 100 to the transaxle 113 to the differential 111 to the drive shaft 109 to the front wheels 110.

As shown in FIG. 14, the drive system of an FR (front engine rear wheel drive) based 4WD vehicle is as follows: engine 100 → transmission 101 → propeller shaft (rear propeller shaft) 102 → differential 103 → drive shaft 104 → rear wheels 105 The driving force is transmitted. Further, on the front side, driving force is transmitted as follows: engine 100 → transmission 101 → transfer 106 → propeller shaft (front propeller shaft) 107 → differential 108 → drive shaft 109 → front wheels 110.

In both FF-based and FR-based 4WD vehicles, constant velocity universal joints 45, 46, and 47 used for drive shafts 104 and 109 that pass through differentials 103, 108, and 111, which serve as the final reduction gears, have a maximum rotation speed of 2000 min. ^-1 , and the normal maximum operating angle is about 15°. As for the behavior of the operating angle, in the constant velocity universal joints 45, 46, 47 used for the drive shafts 104, 109, since the wheels 105, 110 move up and down, an operating angle that follows this is required. is constantly changing. In addition, in the case of the front wheel 110, the fixed constant velocity universal joint 46 on the wheel side requires a large operating angle for steering. In this embodiment, the maximum operating angle of the fixed constant velocity universal joint 46 attached to the front wheel 110 is about 45 degrees, and the maximum operating angle of the other constant velocity universal joints 46 and 47 is about 20 to 25 degrees. It is.

On the other hand, the propeller shafts 102 and 107 are disposed before the differentials 103, 108, and 111, which serve as the final reduction gears, so they are used at high speed rotations, and specifically, the maximum rotation speed is about 8000 min ^-1 . In addition, the differentials 103, 108, 111 are attached to the vehicle body side in an independent suspension vehicle, and the overall length of the propeller shafts 102, 107 is long, so the operating angle of the constant velocity universal joint 1 used for the propeller shafts 102, 107 is: It is small and approximately constant. Specifically, the normal maximum operating angle of the constant velocity universal joint 1 is 10 degrees or less, and the maximum operating angle is about 15 degrees. Furthermore, the constant velocity universal joint 1 used for the propeller shafts 102 and 107 has significantly smaller transmitted torque than the constant velocity universal joints 45, 46, and 47 used for the drive shafts 104 and 109. 13 and 14, the universal joints 43, 44, 48, 49 used in the propeller shafts 102, 107 are illustrated as cross joints, but at least some of these universal joints 43, 44, 48, 49 are , constant velocity universal joints may be used.

An overview of a propeller shaft will be explained based on FIG. 1, taking the propeller shaft of a FF-based 4WD vehicle as an example. The propeller shaft 102 includes a first propeller shaft 41 located at the front (right side in the figure, engine 100 side in FIG. 13) and a second propeller shaft located at the rear (left side in the figure, side toward the differential 103 in FIG. 13). It consists of 42.

The main part of the first propeller shaft 41 is composed of a hollow pipe 64, and one end (front end) is connected to the output side of the engine 100 (transfer 112, see FIG. 13) via a cross joint 43. The sliding constant velocity universal joint 1 is connected to the other end (rear end) of the hollow pipe 64 of the first propeller shaft 41 . This sliding type constant velocity universal joint 1 is a sliding type constant velocity universal joint for a propeller shaft according to this embodiment.

The main part of the second propeller shaft 42 is composed of a hollow pipe 65, and one end (front end) is rotatably supported by a bearing support 60. Specifically, the bearing support 60 includes a bracket 61, an elastic member 62, and a rolling bearing 63. An outer ring 62a of the elastic member 62 fits into the bracket 61, and an inner ring 62b of the elastic member 62 fits into the rolling bearing 63. is fitted. A shaft 20 is provided at one end of the second propeller shaft 42, and the outer periphery of the shaft 20 fits into a rolling bearing 63 and is elastically supported in the radial direction. One end (front end) of the shaft 20 is connected to a connection hole of an inner joint member of the sliding constant velocity universal joint 1 . The other end (rear end) of the second propeller shaft 42 is connected to the differential 103 (see FIG. 13) via a cross joint 44. As described above, the first propeller shaft 41 and the second propeller shaft 42 are connected in the axial direction.

The overall configuration of the sliding type constant velocity universal joint 1 for propeller shafts according to this embodiment will be explained based on FIGS. 2(a) and 2(b).

A sliding type constant velocity universal joint (hereinafter also simply referred to as a sliding type constant velocity universal joint) 1 for a propeller shaft according to the present embodiment is a so-called double offset type sliding type constant velocity universal joint (hereinafter also referred to as a DOJ). ), whose main components include an outer joint member 2, an inner joint member 3, a torque transmission ball 4, and a retainer 5. Eight linear track grooves 7 are formed in the cylindrical inner circumferential surface 6 of the outer joint member 2 at equal intervals in the circumferential direction and along the axial direction. On the spherical outer circumferential surface 8 of the inner joint member 3, eight linear track grooves 9 facing the track grooves 7 of the outer joint member 2 are formed at equal intervals in the circumferential direction and along the axial direction. . One torque transmission ball (hereinafter also simply referred to as a ball) 4 is installed between the linear track groove 7 of the outer joint member 2 and the linear track groove 9 of the inner joint member 3. The balls 4 are housed in pockets 5a of the retainer 5.

The cage 5 has a spherical outer circumferential surface 12 and a spherical inner circumferential surface 13. The spherical outer circumferential surface 12 is fitted and guided in contact with the cylindrical inner circumferential surface 6 of the outer joint member 2, and the spherical inner circumferential surface 13 is It is fitted into and guided in contact with the spherical outer circumferential surface 8 of the inner joint member 3. The spherical outer peripheral surface 12 of the cage 5 has a center of curvature O1, and the spherical inner peripheral surface 13 has a center of curvature O2. The centers of curvature O1 and O2 have an equal offset amount f on the opposite side in the axial direction with respect to the center O3 of the pocket 5a of the retainer 5. Here, the center O3 of the pocket 5a means the intersection of the plane containing the axial centers of each of the eight pockets 5a and the axis NN of the joint. As a result, when the joint takes an operating angle, the ball 4 is always guided on a plane that bisects the angle formed by the axes of the outer joint member 2 and the inner joint member 3, and the rotational torque is equalized between the two axes. transmitted at high speed.

As shown in FIG. 2(a), a large diameter portion 2a is formed at one end of the outer joint member 2 (the right end in FIG. 2(a)) to be joined to the hollow pipe 64 of the first propeller shaft 41. A seal cover 16 is attached to the inner peripheral hole near the portion 2a. A female spline (including serrations) 11 is formed in a connecting hole 10 passing through the axis of the inner joint member 3, and a male spline 21 of a shaft 20 (see FIGS. 1 and 8) is fitted and connected to the connecting hole 10 to prevent a stop. It is fixed in the axial direction by a ring 22.

A retaining ring groove 14 is provided on the inner periphery of the other end (opening side end) of the outer joint member 2 . The retaining ring 23 (see FIG. 8) installed in the retaining ring groove 14 prevents the inner assembly consisting of the inner joint member 3, balls 4, and retainer 5 from slipping out from the open end of the outer joint member 2. To prevent. A cylindrical notch 5c for incorporating the inner joint member 3 is provided on the inner periphery of the large-diameter end (the right end in FIG. 2(a)) of the retainer 5. A boot mounting groove 15 is provided on the outer periphery of the open end of the outer joint member 2 . As shown in FIG. 9, a boot 25 is attached to the boot attachment groove 15 of the outer joint member 2 and the boot attachment groove 20a of the shaft 20, and is fastened and fixed by boot bands 27 and 26. The boot 25 and the seal cover 16 cooperate to prevent the grease sealed inside the joint from leaking to the outside and to prevent foreign matter from entering from outside the joint.

The overall configuration of the sliding type constant velocity universal joint 1 of this embodiment is as described above. Next, the characteristic configuration will be explained. The findings and ideas of the development process that led to the characteristic configuration of the sliding type constant velocity universal joint 1 of this embodiment are as follows.
(1) Double offset type sliding constant velocity universal joints (DOJ) can have a relatively large sliding amount in the axial direction, have a rich track record of use, have stable performance, and can reduce the number of balls. By using eight pieces, it is possible to achieve a reduction in size and weight. Focusing on these points, in order to meet the demands for further fuel efficiency of automobiles, smaller size, lighter weight, and higher rotation speed of propeller shafts, we developed DOJ, which is used in current propeller shafts as shown in Figures 11 and 12. We investigated various aspects. As a result, the current DOJ has a maximum operating angle of about 25° so that it can also be used for drive shafts, but we focused on the point that the functions of DOJ can be limited by specializing in the characteristics required for propeller shafts. did. Specifically, it has been found that by dedicating the DOJ to the propeller shaft, the maximum operating angle can be limited to a low value (for example, 15 degrees or less), and thereby the DOJ can be made smaller and lighter.
(2) By limiting the maximum operating angle of the DOJ dedicated to the propeller shaft to a low value, the following specific technical effects can be obtained.
(a) Compactness and weight reduction in the radial direction by reducing the radial wall thickness of each component (outer joint member, inner joint member, retainer) (b) Reducing the axial movement of the balls in the inner joint member Making the cage more compact and lighter in the axial direction (c) Making the cage more compact and lighter in the radial direction by reducing the circumferential movement of the balls (d) Making the cage more compact and lighter in the axial direction by reducing the pocket load (3) In addition, we focused on the dynamic factors of the small and nearly constant operating angle of DOJ for propeller shafts and high speed rotation, and investigated the possibility of further weight reduction and compactness. As a result, we came up with the idea of reducing the amount of offset of the retainer, and found that this promoted the technical effect (2) above, making it possible to further reduce the weight and size of the DOJ.

The above characteristic configuration will be explained in comparison with the current sliding type constant velocity universal joint shown in FIGS. 11 and 12. As shown in FIGS. 11 and 12, the current sliding type constant velocity universal joint 201 is a double offset type sliding type constant velocity universal joint using eight torque transmission balls 204. The main components are a joint member 203, a torque transmission ball 204, and a retainer 205, and the maximum operating angle is about 25°. The diameter Db of the torque transmission ball 4 of the sliding type constant velocity universal joint 1 according to this embodiment is equal to the diameter Db' of the torque transmission ball 204 of the existing sliding type constant velocity universal joint 201. The basic internal configuration is the same as that of the sliding type constant velocity universal joint 1 for propeller shaft of this embodiment, so the parts having the same functions as the sliding type constant velocity universal joint 1 for propeller shaft of this embodiment are 200 is added to the code given to this embodiment, and alphabetical codes such as the center of the pocket, the center of curvature, and the amount of offset are given a dash (') to the code of this embodiment.

The longitudinal sections of the sliding type constant velocity universal joint 1 according to this embodiment and the current sliding type constant velocity universal joint 201 will be compared and explained based on FIGS. 3(a) and 3(b). 3(a) shows the vertical cross section of the upper half above the axis NN in FIG. 2(a) on the upper side, and the vertical cross section of the upper half above the axis NN in FIG. 11(a) is reversed and shows the lower side. FIG. 3(b) shows the longitudinal section of the lower half below the axis NN in FIG. 2(a) inverted and shown on the upper side, and the longitudinal section of the lower half below the axis NN in FIG. 11(a) is shown on the lower side. FIG.

The maximum operating angle of the sliding constant velocity universal joint 1 of this embodiment shown above the joint axis NN in FIG. 3(b) is set to 15°. Accordingly, the inclination angle β of the conical stopper surface 5d on the outer periphery of the retainer 5 is set to 7.5°, which is 1/2 of the maximum operating angle of 15°. Therefore, as shown in FIG. 8, the sliding constant velocity universal joint 1 can take the maximum operating angle θmax=15° before the boot is attached. However, the maximum operating angle may be set to an appropriate angle of 15° or less. In this manner, when the operating angle is determined, the cylindrical inner circumferential surface 6 of the outer joint member 2 and the conical stopper surface 5d on the outer periphery of the retainer 5 come into contact with each other, thereby regulating the maximum operating angle. In this specification, the maximum working angle has the above meaning. In addition, in the completed state where the sliding type constant velocity universal joint 1 is equipped with a boot, as shown in FIG. 9, when the operating angle is taken, the boot 25 and the shaft 20 come into contact, so that the available operating angle is restricted. , smaller than the maximum working angle above.

In contrast to the above, the maximum operating angle of the current sliding type constant velocity universal joint 201 shown below the joint axis N-N in Fig. 3(b) is set to about 25° so that it can be used for drive shafts. The inclination angle β' of the conical stopper surface 205d on the outer peripheral surface of the retainer 205 is set to 12.5°, which is 1/2 of the maximum operating angle of 25°.

In a ball type constant velocity universal joint, when the operating angle is 0°, each ball receives an equal load, but as the operating angle increases, each ball receives an uneven load, and the higher the operating angle, the greater the difference. growing. Therefore, in the case of a high operating angle, the maximum load applied to one ball increases, so the inner joint member, outer joint member, and retainer that come into contact with the ball cannot withstand the maximum load received from the ball. A thick wall thickness is required. In contrast, in the sliding constant velocity universal joint 1 of the present embodiment, the required strength of the outer joint member 2, inner joint member 3, and retainer 5, which are the component parts, is suppressed by limiting the maximum operating angle to a low value. Therefore, these wall thicknesses can be made thinner. Furthermore, by limiting the maximum operating angle to a low value, the amount of radial movement of the balls 4 within the pockets 5a of the cage 5 at the maximum operating angle is also reduced, so the wall thickness of the cage 5 can be made thinner. .

Specifically, as shown in FIGS. 3(a) and 3(b), the wall thickness To of the outer joint member 2 of the sliding type constant velocity universal joint 1 of this embodiment (in detail, the outer joint member 2 ), the wall thickness Ti of the inner joint member 3 (more specifically, the radius between the groove bottom of the track groove 9 of the inner joint member 3 and the pitch circle of the female spline 11) direction distance) is thinner than the wall thickness To' of the outer joint member 202 and the wall thickness Ti' of the inner joint member 203 of the current sliding type constant velocity universal joint 201. As an optimum value, the ratio Ti/Db between the wall thickness Ti of the inner joint member 3 and the ball diameter Db is 0.30 to 0.45. Further, the ratio To/Db between the wall thickness To of the outer joint member 2 and the ball diameter Db is 0.25 to 0.29.

In a ball type constant velocity universal joint, the higher the operating angle, the greater the amount of movement of the ball in the circumferential direction relative to the retainer. In the current sliding type constant velocity universal joint 201 that uses eight balls, the maximum operating angle is set to about 25 degrees, so the amount of movement in the circumferential direction of the balls 204 relative to the retainer 205 is large, making it difficult to accommodate the balls 204. It is necessary to increase the circumferential length of the pocket 205a of the retainer 205. Further, in order to ensure the strength of the column portions 205b (see FIG. 11(b)) of the cage 205, there is a limit to the reduction in the circumferential dimension of the column portions 205b. As a result, the outer diameter of the retainer 205 became large, and the sliding constant velocity universal joint 201 could not be sufficiently miniaturized. Further, accordingly, the wall thickness Ti' of the inner joint member 203 has also become thicker than necessary.

On the other hand, by limiting the maximum operating angle of the sliding constant velocity universal joint 1 to a low value as described above, the amount of movement in the circumferential direction of the balls 4 in the pockets 5a of the retainer 5 becomes small, so that The circumferential length can be shortened, the diameter of the retainer 5 can be reduced, and the sliding constant velocity universal joint 1 can be made more compact in the radial direction. Further, by reducing the diameter of the retainer 5, the wall thickness of the inner joint member 3 can be optimized, and the pitch circle diameter PCD _BALL of the balls 4 can be reduced. Accordingly, the outer diameter Do of the outer joint member 2 can be reduced. As an optimum value, the ratio PCD _BALL /Db between the pitch circle diameter PCD _BALL of the ball 4 and the diameter Db of the ball 4 is 3.3 or more and 3.6 or less.

Cross sections of the sliding type constant velocity universal joint 1 of this embodiment and the current sliding type constant velocity universal joint 201 are shown in comparison with FIG. 10 . The sliding type constant velocity universal joint 1 of this embodiment has realized a 5% or more compactness in the outer diameter Do of the outer joint member 2 compared to the current sliding type constant velocity universal joint 201. The optimum value of the ratio Do/ PCD _SPL between the outer diameter Do of the outer joint member 2 and the pitch circle diameter PCD _SPL of the female spline 11 is 2.7 or more and 3.0 or less.

In addition, by limiting the maximum operating angle of the sliding constant velocity universal joint 1 to a low value as described above, the strength of the inner joint member 3 can be increased, and the shaft 20, which is the weakest component at low operating angles, is strengthened. can do. That is, the pitch circle diameter (PCD _SPL ) of the female spline 11 of the inner joint member 3 can be increased, and as a result, the strength of the propeller shaft at low operating angles can be improved. As an optimum value, the ratio PCD _SPL /Db between the pitch circle diameter PCD _SPL of the female spline 11 and the diameter Db of the ball 4 is 1.75 or more and 1.85 or less. On the other hand, it is also possible to maintain the pitch circle diameter (PCD _SPL ) of the female spline 11 as it is, thereby promoting compactness of the inner joint member 3 in the radial direction.

In addition, by limiting the maximum operating angle of the sliding type constant velocity universal joint 1 to a low value as described above, the axial width of the inner joint member 3 and the retainer 5 can be shortened, and the sliding type constant velocity universal joint 1 can be The joint 1 can be made lighter and more compact in the axial direction. As shown in FIGS. 3(a) and 3(b), the axial width Wi of the inner joint member 3 of the sliding type constant velocity universal joint 1 and the axial width Wc of the retainer 5 are different from those of the current sliding type This is significantly shorter than the axial width Wi' of the inner joint member 203 of the constant velocity universal joint 201 and the axial width Wc' of the retainer 205.

In the sliding constant velocity universal joint 1 described above, the axial movement amount of the ball 4 is determined by the maximum operating angle, so the axial width Wi of the inner joint member 3 may be set accordingly. The relationship between the axial movement amount of the ball 4 and the axial width Wi of the inner joint member 3 will be specifically explained based on FIG. 4. FIG. 4 shows the axial direction of the inner joint member and the ball in the sliding type constant velocity universal joint 1 according to the present embodiment and the current sliding type constant velocity universal joint 201 used in a propeller shaft. It is a diagram comparing moving states. The amount of axial movement of the ball 4 in the sliding type constant velocity universal joint 1 is Zi, and the amount of axial movement of the ball 204 in the current sliding type constant velocity universal joint 201 is Zi'. The axial movement amount Zi is shorter than the axial movement amount Zi' due to the lower maximum operating angle. Since the axial width Wi of the inner joint member 3 and the axial width Wi' of the inner joint member 203 are set according to the axial movement amounts Zi and Zi', the sliding type constant velocity universal joint 1 is The axial width Wi of the inner joint member 3 is significantly reduced compared to the axial width Wi' of the inner joint member 203 of the current sliding type constant velocity universal joint 201.

If the axial width Wi of the inner joint member 3 is too short, the spline fitting length between the female spline 11 of the inner joint member 3 and the male spline 21 of the shaft 20 will be insufficient, and the connection between the inner joint member 3 and the shaft 20 will be insufficient. A lack of strength occurs. However, by limiting the maximum operating angle of the sliding constant velocity universal joint 1 to a low value as described above, there is a margin in the strength of the inner joint member 3, so the pitch circle diameter (PCD _SPL ) of the female spline 11 is normally Can be set larger. This has an advantageous effect on the torsional strength of the shaft 20, which is the weakest component at low operating angles, and on the spline tooth surface pressure, making it possible to shorten the spline fitting length, thereby reducing the axial width of the inner joint member. It is possible to reduce the weight by shortening Wi. As an optimum value, the ratio Wi/Db between the axial width Wi of the inner joint member 3 and the ball diameter Db is 1.2 to 1.4.

By limiting the maximum operating angle of the sliding constant velocity universal joint 1 as described above, the ball load applied to the pockets 5a of the retainer 5 is reduced. As a result, the axial wall thickness between the axial wall surface of the pocket 5a and the end surface of the retainer 5 (that is, the axial wall thickness of the annular portion provided on both sides of the pocket 5a in the axial direction) can be reduced, resulting in a lighter weight. will be promoted. Specifically, as shown in FIG. 3(b), the axial width Wc of the retainer 5 of the sliding type constant velocity universal joint 1 is the same as the axial width Wc of the retainer 205 of the current sliding type constant velocity universal joint 201. This is significantly reduced compared to the direction width Wc'. As an optimum value, the ratio Wc/Db of the axial width Wc of the cage 5 to the ball diameter Db is 1.8 to 2.0.

The small offset amount of the cage, which has dramatically promoted the technical effects of weight reduction and compactness of the sliding type constant velocity universal joint 1 of the present embodiment described above, will be explained based on FIG. 3(b). do. During the development process, we focused on the dynamic factors of the sliding constant velocity universal joint 1 for propeller shafts, which have a small maximum operating angle, a nearly constant angle, and high speed rotation, and radically explored the possibility of making it lighter and more compact. We considered this. As a result, we came up with the idea that it is possible to reduce the offset amount f of the retainer 5, which dramatically promotes the above-mentioned technical effects and makes the sliding type constant velocity universal joint 1 even lighter and more compact. It turned out that it can be achieved.

As shown in FIG. 3(b), the offset amount f of the cage 5 of the sliding type constant velocity universal joint 1 is compared to the offset amount f' of the cage 205 of the current sliding type constant velocity universal joint 201. It is set small. In the sliding constant velocity universal joint 1, the ratio f/PCD _BALL of the offset amount f of the retainer 5 and the pitch circle diameter PCD _BALL of the ball 4 [see FIG. 3(a)] is as a specification exclusively for the propeller shaft. It is set to 0.07 or more and 0.09 or less. By reducing the amount of offset of the retainer 5, the sliding constant velocity universal joint 1 can be further made lighter and more compact. In addition, by reducing the offset amount f of the cage 5, the force acting on the pocket 5a of the cage 5 and the inner circumferential surface 6 of the outer joint member 2 is reduced. The amount of heat generated in the sliding constant velocity universal joint 1 can be suppressed. Note that the ratio f'/PCD _BALL ' between the offset amount f' of the retainer 205 of the current sliding type constant velocity universal joint 201 and the pitch circle diameter PCD _BALL ' of the ball 204 [see FIG. 3(a)] is: It is set to a value exceeding 0.09.

Table 1 shows each dimensional ratio between the sliding type constant velocity universal joint 1 of this embodiment and the current sliding type constant velocity universal joint 201.

Next, the performance features of the sliding constant velocity universal joint 1 for propeller shafts, such as vibration characteristics, low heat generation, and high speed rotation, will be explained based on FIGS. 5 to 7.

As shown in FIG. 5, an axial pocket clearance δ1 is provided between the axial wall surface of the pocket 5a of the retainer 5 and the balls 4. Assuming that the dimension between the axial wall surfaces of the pockets 5a of the retainer 5 is Lc and the ball diameter Db of the balls 4, the pocket clearance δ1 is expressed as δ1=Lc−Db.

As shown in FIG. 6, an axial clearance δ2 is provided between the spherical inner peripheral surface 13 of the retainer 5 and the spherical outer peripheral surface 8 of the inner joint member 3. The axial clearance δ2 is determined by, for example, moving the inner joint member 3 to one side in the axial direction with the retainer 5 fixed so that the spherical outer circumferential surface 8 of the inner joint member 3 is attached to the spherical inner circumferential surface 13 of the retainer 5. Relative movement in the axial direction from the abutting position to the position where the spherical outer circumferential surface 8 of the inner joint member 3 abuts the spherical inner circumferential surface 13 of the retainer 5 by moving the inner joint member 3 to the other side in the axial direction It's the amount.

By providing the pocket clearance δ1 and the axial clearance δ2 as described above, the sliding resistance of the sliding type constant velocity universal joint 1 is reduced, and the vibration characteristics of the vehicle can be improved. It is expected that the life of the quick adjustable joint 1 will be improved. This is particularly effective for propeller shafts, which rotate at higher speeds than drive shafts.

The pocket gap δ1 is preferably set to 0 to 0.05 mm. Even if the pocket gap δ1 is provided even a little, it can be effective. In addition, if the pocket clearance δ1 is larger than 0.05 mm, the amount of deviation of the ball 4 from the bisector of the working angle will increase, resulting in a decrease in the constant velocity and durability of the sliding type constant velocity universal joint 1. There is a possibility of connection.

The axial clearance δ2 is preferably set to about 0.5 to 1.5 mm. If the axial clearance δ2 is smaller than 0.5 mm, the amount of vibration from the engine (the amount of axial amplitude) cannot be absorbed by the amount of relative axial movement between the inner joint member 3 and the retainer 5, and the vibration is There is a possibility that it will be transmitted. On the other hand, if the axial clearance δ2 is larger than 1.5 mm, the amount of deviation of the ball 4 from the bisector of the working angle will increase, and the constant velocity and durability of the sliding constant velocity universal joint 1 will decrease. may lead to.

Specifications of the pocket clearance δ1 and the axial clearance δ2 will be explained based on FIGS. 7(a), 7(b), and 7(c). In the standard specification shown in FIG. 7(a), an axial pocket clearance δ1 is not provided between the axial wall surface of the pocket 5a of the retainer 5 and the ball 4. Furthermore, the radius of curvature Rc of the spherical inner circumferential surface 13 of the retainer 5 and the radius of curvature Ri of the spherical outer circumferential surface 8 of the inner joint member 3 are substantially Rc ≒Ri, and the axial clearance δ2 is not provided.

As shown in FIGS. 7(b) and 7(c), the sliding constant velocity universal joint 1 of this embodiment has a pocket clearance δ1 and an axial clearance δ2 (see FIG. 5). There is. In the specification shown in FIG. 7(b), a pocket clearance δ1 is provided, the radius of curvature Rc' of the spherical inner circumferential surface 13 of the cage 5 is made larger than the radius of curvature Ri of the spherical outer circumferential surface 8 of the inner joint member 3, and , the center of curvature of the radius of curvature Rc' is offset from the axis of the retainer 5 in the radial direction. As a result, the spherical outer peripheral surface 8 of the inner joint member 3 and the spherical inner peripheral surface 13 of the cage 5 come into contact at the axial center of the inner joint member 3, but there is an axial clearance δ2 (Fig. 5) is formed.

FIG. 7(c) shows another specification in which a pocket clearance δ1 and an axial clearance δ2 are provided. In this specification, the spherical outer circumferential surface 8 of the inner joint member 3 is formed of a single spherical surface with a radius of curvature Ri, but the spherical inner circumferential surface 13 of the retainer 5 is located at the center of the inner joint member 3 in the axial direction. A cylindrical portion 13a is formed at a corresponding position within a range S, and a spherical surface with a radius of curvature Rc is smoothly connected to both ends of the cylindrical portion 13a. The radius of curvature Rc of the spherical inner circumferential surface 13 of the retainer 5 and the radius of curvature Ri of the spherical outer circumferential surface 8 of the inner joint member 3 are substantially Rc≈Ri, although there is a slight spherical clearance for sliding guidance. It is. In this specification, when the cage 5 and the inner joint member 3 move relative to each other in the axial direction, the axial center of the spherical outer peripheral surface 8 of the inner joint member 3 is slidably guided by the cylindrical portion 13a, so that the cage 5 and the inner joint member 3 move smoothly. Can move relatively.

The present invention is not limited to the embodiments described above, and can of course be implemented in various forms without departing from the gist of the present invention. It is defined by the claims, and includes the full meaning of equivalents and all changes within the scope of the claims.

1 Sliding constant velocity universal joint for propeller shaft 2 Outer joint member 3 Inner joint member 4 Torque transmission ball 5 Retainer 102 Propeller shaft 107 Propeller shaft O1 Center of curvature of spherical outer peripheral surface of retainer O2 Spherical inner peripheral surface of retainer Center of curvature O3 Center of cage pocket

Claims (6)

A sliding constant velocity universal joint for a propeller shaft,
an outer joint member in which eight linear track grooves are formed along the axial direction on a cylindrical inner circumferential surface; and eight linear track grooves in a spherical outer circumferential surface facing the linear track grooves of the outer joint member. is formed along the axial direction and is incorporated between an inner joint member having a connecting hole in which a female spline is formed, and a linear track groove of the outer joint member and a linear track groove of the inner joint member. The torque transmitting balls are housed in pockets, and the spherical outer circumferential surface of the outer joint member is guided in contact with the cylindrical inner circumferential surface of the outer joint member, and the spherical outer circumferential surface of the inner joint member is guided in contact with the spherical outer circumferential surface of the inner joint member. and a cage having a spherical inner circumferential surface, wherein the center of curvature of the spherical outer circumferential surface and the center of curvature of the spherical inner circumferential surface of the cage are each equal to the opposite side in the axial direction with respect to the center of the pocket. has an offset amount (f),
The maximum operating angle of the sliding constant velocity universal joint for the propeller shaft is set to 15° or less,
The ratio Ti/Db of the wall thickness Ti of the inner joint member and the ball diameter Db of the torque transmission ball is 0.30 or more and 0.45 or less,
The ratio PCD _BALL /Db of the pitch circle diameter PCD BALL of the torque transmission ball and the diameter _Db of the torque transmission ball is 3.3 or more and 3.6 or less,
A sliding constant velocity universal joint for a propeller shaft, wherein a ratio Wc/Db of the width Wc of the retainer and the ball diameter Db of the torque transmission ball is set to be 1.8 or more and 2.0 or less. The propeller shaft according to claim 1, wherein a ratio PCD _SPL /Db of the pitch circle diameter PCD _SPL of the female spline of the inner joint member and the ball diameter Db of the torque transmission ball is 1.75 or more and 1.85 or less. Sliding type constant velocity universal joint. The propeller according to claim 1 or 2, wherein the ratio Do/PCD _{SPL of the outer diameter Do of the outer joint member and the pitch circle diameter PCD SPL of} the female spline of the inner joint member is 2.7 or more and 3.0 or less. Sliding type constant velocity universal joint for shaft. The propeller according to any one of claims 1 to 3, wherein the ratio f/PCD _BALL between the offset amount (f) and the pitch circle diameter PCD _BALL of the torque transmission ball is 0.07 or more and 0.09 or less. Sliding type constant velocity universal joint for shaft. An axial pocket clearance δ1 is provided between the axial wall surface of the pocket and the torque transmission ball, and an axial clearance δ2 is provided between the spherical inner circumferential surface of the retainer and the spherical outer circumferential surface of the inner joint member. The sliding type constant velocity universal joint for a propeller shaft according to any one of claims 1 to 4, wherein the sliding type constant velocity universal joint for a propeller shaft is provided. The sliding type constant velocity universal joint for a propeller shaft according to claim 5, wherein the pocket clearance δ1 is 0 to 0.05 mm, and the axial clearance δ2 is 0.5 to 1.5 mm.

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