JP2001113972A - Drive shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve NVH performance of a vehicle by suppressing high-degree vibration of a drive shaft. SOLUTION: In a drive shaft having an intermediate shaft 50 on one end of which a slide type constant velocity universal joint 51 is mounted and on the other end of which a fixed type constant velocity universal joint 53 is mounted, in a way that the slide type constant velocity universal joint 51 and the fixed type constant universal joint 53 are brought into vibration characteristics different in a degree, overlap at a low degree of vibration component with each other is prevented from occurring, the number of the overlapping times is decreased and the increase of amplitude is suppressed. For example, a ball type constant velocity universal joint using eight balls is employed in the fixed constant velocity universal joint 53, and a ball type constant velocity universal joint using six balls or a tripod type constant velocity universal joint is employed in the slide type constant velocity universal joint 51.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive shaft for transmitting the power of an automobile engine to wheels, and more particularly, to an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and an intermediate shaft. It relates to a drive shaft composed of a slide type constant velocity universal joint attached to the other end, and prevents a beat sound from being generated due to the drive shaft vibration being related to engine vibration, etc. This is to improve noise characteristics.

[0002]

2. Description of the Related Art A drive shaft of an automobile is composed of an independent suspension type drive wheel axle and a differential (final reduction gear).
It is used to transmit driving force between and. The drive wheel axle has a role of sharing the vehicle load and a role of transmitting the driving force to the wheels. In addition, since the front axle of the drive wheel requires a steering function, it is required to have a large operating angle and uniform velocity.
Further, in the independent suspension system, since the differential is attached to the vehicle body, an operating angle that allows the movement of the suspension due to the bounce of the wheels or the vehicle body is required. Although this operating angle is not as large as the wheel-side joint, it is necessary to allow the length of the axle to follow the movement of the suspension. In order to meet these requirements, the wheel-side joints have barfield type fixed type (zeppa type),
A fixed joint such as a tripod fixed type is used. On the other hand, a slide joint such as a bar field type slide type, a tripod type slide type, and a cross groove type (rebro type) is used as the vehicle body side joint. Conventionally, in ball type constant velocity universal joints such as a bar field type and a cross groove type, six balls are used as torque transmitting elements.

For example, the drive shaft shown in FIGS. 9 and 10 includes an intermediate shaft 50 and constant velocity universal joints 51 and 53 mounted on both ends thereof. One constant velocity universal joint 51 is for connecting the end of the intermediate shaft 50 to the output shaft of the differential 52. The intermediate shaft 50 can be bent with respect to the output shaft of the differential 52, and It can slide in any direction. The other constant velocity universal joint 53 is an intermediate shaft 5
0 is a fixed type constant velocity universal joint for connecting the end portion of the driving wheel axle 54 to the driving wheel axle 54,
Only bending is possible. According to such a configuration, even if the drive wheels move up and down during traveling of the vehicle, the angle of the intermediate shaft 50 changes following the movement of the drive wheels. Torque can be transmitted to the drive wheel axle 54 at a constant speed. In addition, a ball type constant velocity universal joint, which can provide a large operating angle on both the slide side and the fixed side, is used, and in particular, a ball type constant velocity universal joint on the fixed side (drive wheel side). By adopting the above, it is possible to increase the allowable range of the relative angle change between the drive wheel axle 54 and the intermediate shaft 50, and it is possible to suitably cope with a case where the stroke of the drive wheel moving up and down is large.

[0004]

SUMMARY OF THE INVENTION Constant velocity universal joints 51, 5
When torque is transmitted in a state where the third shaft 3 and the intermediate shaft 50 are at an angle, a bending moment (secondary moment) for bending the intermediate shaft 50 is generated. That is, the constant velocity universal joints 51 and 53 have a structure in which torque is transmitted by torque transmitting elements (balls or rollers) arranged at equal angular intervals inside each of them. In such a structure, when the output shaft of the differential 52, the intermediate shaft 50, and the drive wheel axle 54 are in a straight line, the torque transmitting element does not cause a particularly remarkable behavioral operation, and a large vibrating force. Does not cause
When the above three members are bent in a non-linear manner, a phenomenon in which the torque transmitting element behaves greatly is observed, and this phenomenon becomes a vibrating force of the drive shaft and is transmitted to the vehicle body to produce sound.

When the drive wheels move up and down while the vehicle is running, FIG.
As shown in FIG. 0, the intermediate shaft 50 is inclined at the angle α. In such a situation, when a torque is input from the differential 52 to the intermediate shaft 50 and transmitted to the drive wheel axle 54, the direction of the torque input to the intermediate shaft 50 and the reaction from the drive wheels occur. Due to the directions of the torque being different from each other, a bending moment for maintaining the above-mentioned torque balance is generated on the drive shaft. Specifically, as shown in FIG. 11, if the input torque to the intermediate shaft 50 is T1, and the reaction torque from the drive wheels is T2, the directions of these torques T1 and T2 are different, so that the A rotational moment M for maintaining the balance of these torques in some way should be involved. The bending moment M can be divided into a moment M1 in a direction perpendicular to the output shaft of the differential 52 and a bending moment M2 in a direction perpendicular to the drive wheel axle 54, and M1 and M2 are secondary moments. When M1 and M2 are positive second moments, M1 'and M2' in opposite directions are negative second moments.

This secondary moment has a periodic fluctuation component related to the structure of the constant velocity universal joint, and becomes a vibrating force for vibrating the drive shaft. Usually, the vibration of the drive shaft due to the second moment is considerably smaller in level than the vibration of the engine, and does not cause unpleasant vibration and noise by itself, but the frequency is the same as the frequency of the vibration of the engine. When approaching, there is a problem that a resonance (resonance) phenomenon occurs in the passenger compartment, and an abnormal noise called a muffled sound or a beat sound is generated, which causes discomfort to the occupant.

For example, when both ends of a drive shaft are connected by using a fixed type constant velocity universal joint having six balls and a slide type constant velocity universal joint, the secondary moment acting on the constant velocity universal joint is fixed. In both the sliding type and the sliding type, the sixth order fluctuation component related to the number of balls and the angle phase is mainly used, and the peak value (maximum value, minimum value) of the fluctuation of each secondary moment also appears at the same rotation angle. Therefore, the total secondary moment (fixed type + sliding type) obtained by combining the secondary moments of the fixed type and the sliding type constant velocity universal joint is mainly composed of the sixth order fluctuation component, and the amplitude thereof is also amplified and increased.

Here, the frequency of the sixth order variation component of the second moment (fixed type + sliding type) is FD6, the rotation speed of the wheel is FWHEEL, and the rotation speed of the engine is FENGIN.
E, if the differential reduction ratio is 0.35,
FD6 is 6 times FWHEEL, so FD6 = 6 × FWHEEL
= 6 × FENGINE × 0.35 = FENGINE × 2.1.
On the other hand, since the vibration of the engine is mainly composed of the second-order fluctuation component, FD6 = (2 × FENGINE) × 1.05, and the frequency FD6 of the sixth-order fluctuation component of the second moment is equal to 2
It is 1.05 times the frequency of the next fluctuation component (2 × FENGINE). As described above, when the two frequencies come close to each other, a resonance (resonance) phenomenon easily causes abnormal noise in the vehicle interior.

The fixed constant velocity universal joint has six balls, and the slide constant velocity universal joint has three rollers in the case of a tripod type and six balls in the case of a ball type. An NVH problem due to the third and sixth rotations occurs. On the fixed side, since the number of balls is 6, a sixth-order vibration component is generated, but at the same time, a third-order vibration component is also generated. This is probably because the outer joint member has six guide grooves, and the outer joint member is easily triangularly deformed. Therefore, overlapping of the same order vibration components generated on the fixed side and the slide side adversely affects the NVH characteristics of the vehicle.

Further, when vibration components of the same order are combined, the amplitude increases or decreases depending on the phase (see FIGS. 12 and 1).
3). In addition, as proposed in Japanese Patent Application Laid-Open No. 10-122253, it is possible to reduce the amplitude by performing phase matching of the balls of the fixed-side constant velocity universal joint and the slide-side constant velocity universal joint. There is a problem that more man-hours are required for phase matching.

An object of the present invention is to improve the NVH performance of a vehicle by suppressing higher-order vibration of a drive shaft.

[0012]

In order to solve the above-mentioned problems, the present invention provides a fixed type constant velocity universal joint and a slide type constant velocity universal joint having vibration characteristics having different orders, thereby reducing the vibration component in a low order. Are avoided, and the number of times of the overlap is also reduced to suppress an increase in amplitude. Although the amplitude cannot be reduced, it is not necessary to adjust the phase because it requires man-hours, and the amplitude of the vehicle NV
It can be suppressed to a level that does not affect the H characteristics.

[0013] For example, as described in claim 1 and claim 2, a constant velocity universal joint using eight balls on the fixed side and six balls on the slide side are used. , The fixed side has the vibration characteristic of the eighth rotation and the slide side has the vibration characteristic of the sixth rotation.
H characteristics are improved.

That is, the invention of claim 1 comprises an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. In the drive shaft, the fixed type constant velocity universal joint has an outer joint member formed with eight guide grooves extending in an axial direction on an inner peripheral surface of a concave spherical surface, and an outer joint member formed on an outer peripheral surface of a convex spherical shape in an axial direction. An inner joint member formed with eight extending guide grooves, and eight balls respectively arranged on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member; A cage for holding the ball in the same plane, wherein the slide-type constant velocity universal joint has six guide grooves extending in the axial direction on a cylindrical inner peripheral surface; Axial on spherical outer surface An inner joint member having six guide grooves formed therein, and six balls respectively arranged on six ball tracks formed by a pair of guide grooves of the outer joint member and the guide groove of the inner joint member. And a cage for holding the ball in the same plane.

A second aspect of the present invention comprises an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. In the drive shaft,
An outer joint member in which the fixed type constant velocity universal joint has eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface; and eight guide grooves extending in the axial direction on a convex spherical outer peripheral surface. And eight balls arranged respectively on eight ball tracks formed by a guide groove of the outer joint member and a guide groove of the inner joint member forming the pair, and the balls are flush with each other. An outer joint member having an inner peripheral surface formed with six guide grooves inclined with respect to the axis, and an outer joint member having an outer peripheral surface with respect to the axis. An inner joint member having six guide grooves inclined in the opposite direction to the guide groove of the joint member, and six balls formed by a pair of outer joint member guide grooves and inner joint member guide grooves. The six balls arranged on the track and the balls are flush with each other Characterized by comprising a cage for holding the.

According to a third aspect of the present invention, a constant velocity universal joint using eight balls is employed on the fixed side, and a tripod type constant velocity universal joint is employed on the slide side. Since the fixed side has an eighth-order vibration characteristic and the slide side has a third-order vibration characteristic, the NVH characteristics of the vehicle are improved.

That is, the invention of claim 3 comprises an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. In the drive shaft, the fixed type constant velocity universal joint has an outer joint member formed with eight guide grooves extending in an axial direction on an inner peripheral surface of a concave spherical surface, and an outer joint member formed on an outer peripheral surface of a convex spherical shape in an axial direction. An inner joint member formed with eight extending guide grooves, and eight balls respectively arranged on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member; And a cage for holding the ball in the same plane, wherein the slide-type constant velocity universal joint is formed with three track grooves having roller guide surfaces arranged circumferentially facing each other. Components, A tripod member having three leg shafts protruding in a radial direction, and a roller rotatably supported by the leg shaft and movable in an axial direction of an outer joint member along the roller guide surface. And

The invention according to claim 4 comprises an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. In the drive shaft,
An outer joint member in which the fixed type constant velocity universal joint has eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface; and eight guide grooves extending in the axial direction on a convex spherical outer peripheral surface. And eight balls arranged respectively on eight ball tracks formed by a guide groove of the outer joint member and a guide groove of the inner joint member forming the pair, and the balls are flush with each other. An outer joint member formed with three track grooves having roller guide surfaces disposed circumferentially facing each other, and a radially extending sliding joint. A tripod member having three protruding leg shafts; and a roller rotatably supported by the leg shaft and movable in an axial direction of an outer joint member along the roller guide surface. A ring is rotatably interposed between the rollers. The inner peripheral surface of the ring is formed in an arc-shaped convex cross-section, and the outer peripheral surface of the leg shaft is formed in a straight shape in a vertical cross-section, and in a cross-section, in a direction orthogonal to the axis of the joint. It is characterized in that a clearance is formed between the ring and the inner peripheral surface in the axial direction of the joint while being in contact with the inner peripheral surface. Regarding the cross-sectional shape of the leg shaft, what is a shape that makes contact with the inner peripheral surface of the ring in a direction perpendicular to the axis of the joint and that forms a clearance with the inner peripheral surface of the ring in the axial direction of the joint? In other words, it means a shape in which the surface portions of the tripod member facing each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface. One specific example is an elliptical shape (claim 5).

By adopting the above-described cross section of the leg shaft, which has been conventionally circular, when the joint takes an operating angle, the leg shaft is inclined with respect to the outer joint member without changing the attitude of the roller assembly. be able to. In addition, since the contact ellipse between the outer peripheral surface of the leg shaft and the ring approaches the point from the horizontal direction (see FIG. 5C), the friction moment for tilting the roller assembly is reduced. Therefore, the attitude of the roller assembly is always stable, and the roller can be smoothly rolled because the roller is held parallel to the roller guide surface. This contributes to a reduction in slide resistance and a reduction in induced thrust. Further, there is an advantage that the bending strength of the leg shaft is improved by increasing the section modulus of the base portion of the leg shaft.

The roller assembly plays a role of transmitting torque by being interposed between the leg shaft and the outer joint member. The direction of torque transmission in this kind of constant velocity universal joint is always the axis of the joint. Since the leg shaft and the ring are in contact with each other in the direction of torque transmission, torque transmission is possible, and even if there is a clearance between the two in the axial direction of the joint, torque transmission will not be hindered. Never come.

According to a fifth aspect of the present invention, in the drive shaft according to the fourth aspect, the cross section of the leg shaft is substantially elliptical in which the major axis is perpendicular to the axis of the joint. The substantially elliptical shape is not limited to a literal ellipse, but includes a shape generally called an oval shape, an oval shape, or the like.

According to a sixth aspect of the present invention, in the drive shaft according to the fourth or fifth aspect, the generatrix of the inner peripheral surface of the ring is constituted by an arc portion at the center and a relief portion at both ends. Features. It is preferable that the radius of curvature of the arc portion is set to a value that allows the inclination of the leg axis of about 2 to 3 °.

According to a seventh aspect of the present invention, in the drive shaft according to any one of the fourth to sixth aspects, a plurality of rolling elements are arranged between the ring and the roller so that the ring and the roller can be relatively rotated. Features. The invention of claim 8 is
The drive shaft according to claim 7, wherein the rolling element is a needle roller.

According to a ninth aspect of the present invention, in the drive shaft according to any one of the third to eighth aspects, the outer peripheral surface of the roller is formed in a spherical shape, and the spherical outer peripheral surface of the roller is a roller guide surface of the outer joint member. Make angular contact. Since the roller and the roller guide surface make an angular contact, the roller is less likely to oscillate and its posture is further stabilized, so that when the roller moves in the axial direction of the outer joint member, it has less resistance on the roller guide surface. Roll smoothly. If a specific configuration for realizing such an angular contact is exemplified, the cross-sectional shape of the roller guide surface may be a tapered shape or a gothic arch shape.

According to a tenth aspect, in the drive shaft according to any one of the first to ninth aspects, the intermediate shaft is hollow. By making the intermediate shaft hollow, the number of balls of the fixed type constant velocity universal joint is reduced to 8
Combined with the miniaturization and compactness due to the individualization, the weight reduction of the drive shaft by 15 to 20% can be achieved.

[0026]

Embodiments of the present invention will be described below with reference to the drawings.

The embodiment shown in FIG.
0, one end of which is equipped with a tripod type sliding constant velocity universal joint 51 which is a kind of a sliding type constant velocity universal joint, and the other end thereof is a barfield type fixed type which is a kind of a fixed type joint. The speed universal joint 53 is mounted. As shown in the drawing, the intermediate shaft 50 is formed in a cylindrical shape over the entire length to reduce the weight.

First, the fixed side will be described. As shown in FIG. 2, a Barfield type fixed type constant velocity universal joint, which is a kind of the fixed type constant velocity universal joint 53, comprises an outer joint member 1, an inner joint member 2, Eight balls 3 and a cage 4 are main components. The outer joint member 1 has a concave spherical inner peripheral surface 1a, and eight guide grooves 1b are formed in the axial direction at equal intervals in the circumferential direction of the inner peripheral surface 1a. Inner joint member 2
Has a convex spherical outer peripheral surface 2a, and eight guide grooves 2b are formed in the axial direction at equal intervals in the circumferential direction of the outer peripheral surface 2a. A serration hole or a spline hole 2c is formed in the axial center portion of the inner joint member 2 so as to be engaged with one end of the intermediate shaft 50. Guide groove 1 of outer joint member 1
b and the guide groove 2b of the inner joint member 2 form a pair to form eight ball tracks, and one ball 3 is incorporated in each ball track. All balls 3 are held in the same plane by a cage 4.

In this embodiment, the center of curvature O1 of the guide groove 1b of the outer joint member 1 is relative to the center of the spherical surface of the inner peripheral surface 1a, and the center of curvature O2 of the guide groove 2b of the inner joint member 2 is the center of the outer peripheral surface 2a. The center of curvature O1 is offset to the opening side of the joint, and the center of curvature O2 is offset to the back side of the joint with respect to the center of the spherical surface by an equal distance (F) in the axial direction. Therefore, the ball track formed by the guide grooves 1b and 2b has a shape open in a wedge shape toward the opening side of the joint.

The center of the spherical surface of the outer peripheral surface 4a of the cage 4 and the center of the spherical surface of the inner peripheral surface 1a of the outer joint member 1 serving as the guide surface of the outer peripheral surface 4a of the cage 4 both include the center O3 of the ball 3. It is in the joint center plane O. The spherical center of the inner peripheral surface 4b of the cage 4 and the inner peripheral surface 4b of the cage 4
The center of the spherical surface of the outer peripheral surface 2a of the inner joint member 2 serving as the guide surface is located within the joint center plane O. Therefore, the offset amount F of the outer joint member 1 is equal to the center O of the guide groove 1b.
1 is equal to the axial distance between the joint center plane O and the offset amount F of the inner joint member 2 is equal to the center O2 of the guide groove 2b.
And the joint center plane O is equal to the axial distance. The center O1 of the guide groove 1b of the outer joint member 1 and the center O2 of the guide groove 2b of the inner joint member 2 are offset from each other by the same distance (F) in the axial direction with respect to the joint center plane O. . That is,
The center O1 of the guide groove 1b is located on the opening side of the joint, and the center O2 of the guide groove 2b is located on the back side of the joint.

When the outer joint member 1 and the inner joint member 2 form an angle, the ball 3 held by the cage 4 is maintained in a plane that bisects the operating angle θ at any operating angle θ. As a result, the distance from the center O3 of the ball 3 to the axis of the outer joint member 1 is always equal to the distance from the axis of the inner joint member 2, so that the constant velocity of the joint is ensured.
Here, the length of a line connecting the center O1 of the guide groove 1b of the outer joint member 1 and the center O3 of the ball 3, and the line connecting the center O2 of the guide groove 2b of the inner joint member 2 and the center O3 of the torque transmitting ball 3 The length of each minute is PCR, and both are equal. The ratio r1 between the diameter of the ball 3 (DBALL) and the pitch circle diameter of the ball 3 (PCDBALL) is r1 = PCDBALL / DBALL.
It can be a value within the range of 3.3 ≦ r1 ≦ 5.0.
The reason for setting 3.3 ≦ r1 ≦ 5.0 is that the strength of the outer joint member, the load capacity and the durability of the joint are fixed constant velocity universal joints using six balls (hereinafter referred to as “comparative products”). ) Or more. That is, in the constant velocity universal joint, it is difficult to largely change the pitch circle diameter (PCDBALL) of the ball within a limited space. Therefore, the value of r1 is mainly the diameter of the ball (DBALL)
Will depend on If r1 <3.3 (mainly when the diameter DBALL is large), the thickness of other parts (the outer joint member, the inner joint member, etc.) becomes too thin, and there is a concern about strength. Conversely, if r1> 5.0 (mainly when the diameter DBALL is small), the load capacity becomes small, and there is a concern in terms of durability. Also, as the diameter DBALL decreases, the contact ellipse at the contact portion decreases, and the surface pressure at the contact portion between the ball and the guide groove increases, which may cause chipping at the groove shoulder edge of the guide groove. You. By setting 3.3 ≦ r1 ≦ 5.0, the strength of the outer joint member, the load capacity of the joint, and the durability can be secured to be equal to or more than those of the comparative product. More preferably, the value is set in the range of 3.5 ≦ r1 ≦ 5.0, for example, r1 = 3.83 or a value in the vicinity thereof.

The outer diameter (DOUTER) of the outer joint member 1 and the tooth shape (serration or spline) 2 of the inner joint member 2
The ratio r2 of pitch c to the pitch circle diameter (PCDSERR) (= DOUTER /
PCDSERR) can be set to a value in the range of 2.5 ≦ r2 ≦ 3.5. The reason for 2.5 ≦ r2 ≦ 3.5 is as follows. The pitch circle diameter (PCDSERR) of the tooth mold 2c of the inner joint member cannot be largely changed in relation to the strength of the drive shaft and the like. Therefore, the value of r2 mainly depends on the outer diameter (DOUTER) of the outer joint member. If r2 <2.5 (mainly when outer diameter DOUTER is small), each part (outer joint member, inner joint member, etc.)
Is too thin, which raises concerns about strength. On the other hand, if r2> 3.5 (mainly when the outer diameter DOUTER is large), practical problems may arise from the viewpoint of dimensions and the like, and the object of compactness cannot be achieved.
By setting 2.5 ≦ r2 ≦ 3.5, the strength of the outer joint member and the like and the durability of the joint can be secured to be equal to or more than those of the comparative product, and the practical demand can be satisfied. Preferably, 2.5 ≦ r2 <3.2.

In the constant velocity universal joint of this embodiment, the number of balls 3 is 8, and the load ratio per ball in the total load capacity of the joint is smaller than that of the comparative product. The diameter (DBALL) of the ball 3 is made smaller than that of the comparative product, and the thickness of the outer joint member 1 and the inner joint member 2 are reduced.
It is possible to ensure the same thickness as that of the comparative product.
For comparison products of the same nominal size, the ratio r2 (= DOUTE
R / PCDSERR) (the general value of r2 in the comparative product is r2 ≥ 3.2), and the outer diameter ( D
OUTER) can be made even more compact. Further, it has been confirmed through experiments that the heat generation is lower than that of the comparative product.

Although not shown in the drawings, a so-called undercut-free type in which the guide groove has a high angle by eliminating the undercut of the guide groove may be adopted as a modified embodiment of the above-mentioned fixed constant velocity universal joint of the Barfield type. .

Referring to the slide side, FIGS. 3 and 4 show a tripod type slide type constant velocity universal joint which is a kind of the slide type constant velocity universal joint 21. FIG. Here, FIG. 3A shows a cross section of the joint, and FIG.
2 shows a longitudinal section of the joint in a state of FIG.

This constant velocity universal joint comprises an outer joint member 10 and a tripod member 20, and the outer joint member 10 has three track grooves 12 extending in the axial direction on the inner peripheral surface. Roller guide surfaces 14 are formed on circumferentially opposite side walls of each track groove 12. The tripod member 20 has three radially protruding leg shafts 22, and a roller 34 is mounted on each leg shaft 22, and the roller 34 is housed in the track groove 12 of the outer joint member 10. The outer peripheral surface of the roller 34 is a convex curved surface that conforms to the roller guide surface 14.

Here, the outer peripheral surface of the roller 34 is
Is a convex curved surface having an arc having a center of curvature at a position radially away from the axis of the roller, and the cross-sectional shape of the roller guide surface 14 is a Gothic arch shape. Make angular contact. In FIG. 3 (A), the two hit positions are indicated by alternate long and short dash lines. Even if the cross-sectional shape of the roller guide surface 14 is tapered with respect to the outer peripheral surface of the spherical roller, angular contact between the two can be realized. By employing a configuration in which the roller 34 and the roller guide surface 14 make an angular contact in this manner, the roller is less likely to oscillate, and the posture is stabilized. When the angular contact is not adopted, for example, the roller guide surface 14 is formed by a part of a cylindrical surface whose axis is parallel to the axis of the outer joint member 10,
The cross-sectional shape may be an arc corresponding to the generatrix of the outer peripheral surface of the roller 34.

A ring 32 is fitted on the outer peripheral surface of the leg shaft 22. The ring 32 and the roller 34 are unitized via a plurality of needle rollers 36, and constitute a roller assembly that can be relatively rotated. That is, with the cylindrical outer peripheral surface of the ring 32 as the inner raceway surface and the cylindrical inner peripheral surface of the roller 34 as the outer raceway surface, the needle rollers 36 are rollably interposed between the inner and outer raceway surfaces. As shown in FIG. 3 (B), the needle rollers 36 have as many rollers as possible.
It is installed in a so-called full roller state without a retainer. Reference numerals 33 and 35 denote a pair of washers mounted in an annular groove formed on the inner peripheral surface of the roller 34 for preventing the needle rollers 36 from falling off.

The outer peripheral surface of the leg shaft 22 has a longitudinal section (FIG. 4).
(A)) has a straight shape parallel to the axis of the leg shaft 22, and a cross section (FIG. 3 (B)) has an elliptical shape whose major axis is orthogonal to the axis of the joint. The cross-sectional shape of the leg shaft is
The thickness of the tripod member 20 as viewed in the axial direction is reduced, and the tripod member 20 has a substantially elliptical shape. In other words, the cross-sectional shape of the leg shaft is
The surfaces of the tripod members facing each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

The inner peripheral surface of the ring 32 has an arc-shaped convex cross section. That is, the generatrix of the inner peripheral surface is a convex arc having a radius r (FIG. 3C). Because of this, the cross-sectional shape of the leg shaft 22 is substantially elliptical as described above, and a predetermined clearance is provided between the leg shaft 22 and the ring 32, the ring 3
2 is not only capable of moving the leg shaft 22 in the axial direction, but also is swingable about the leg shaft 22. Since the ring 32 and the roller 34 are unitarily rotatable via the needle rollers 36 as described above, the leg shaft 2
In relation to 2, the ring 32 and the roller 34 are swingable as a unit. Here, the swing means that the axes of the ring 32 and the roller 34 are inclined with respect to the axis of the leg shaft 22 in a plane including the axis of the leg shaft 22 (see FIG. 4A).

If the outer peripheral surface of the leg shaft 22 is in contact with the inner peripheral surface of the ring 32 over the entire circumference, the contact ellipse has a horizontally long shape extending in the circumferential direction. Therefore, when the leg shaft 22 is inclined with respect to the outer joint member 10, the ring 32 is extended with the movement of the leg shaft 22, and
A frictional moment acting to tilt 4 is generated. On the other hand, in the embodiment shown in FIG.
2 has a substantially elliptical cross-section, and the cross-section of the inner peripheral surface of the ring 32 is cylindrical. As shown by a broken line in FIG. At the same time, the area is reduced. Therefore, the roller assembly (32,
34), the force for tilting the roller 3 is greatly reduced.
4 further improves the stability of the posture.

In the embodiment shown in FIGS. 5 and 6, the generatrix of the inner peripheral surface of the ring 32 is formed by a single arc in the above-described embodiment, while the central arc portion 32a
Only in that it is formed in combination with the escape portions 32b on both sides thereof. In FIG. 5A, some parts, namely, the ring 32, the roller 34, and the washers 33 and 35 are shown.
Are cross-sectioned, but hatching indicating the cross-section is omitted to avoid convergence with the leader line and the center line. The escape portion 32b is a portion for avoiding interference with the leg shaft 22 when the operating angle θ is set as shown in FIG. 5C, and gradually from the end of the arc portion 32a toward the end of the ring 32. It is composed of a straight line or a curve whose diameter is enlarged. here,
The case where the relief portion 32b is a part of a conical surface with a cone angle β = 50 ° is illustrated. The arc portion 32a has a large radius of curvature R of, for example, about 30 mm in order to allow a tilt of the leg shaft 22 with respect to the ring 32 of about 2 to 3 °. In the tripod type constant velocity universal joint, when the outer joint member 10 makes one rotation, the tripod member 20 is mechanically connected to the outer joint member (1).
Swing 3 times around the center of 0). At this time, the amount of eccentricity represented by the symbol e (FIGS. 4A and 5C) is equal to the operating angle θ.
Increase in proportion to And the three leg shafts 22 are 120
°, but when the operating angle θ is taken, FIG. 4 (B)
As shown in the figure, the vertical leg shaft 22 shown at the top of the figure
, The other two leg shafts 22 are slightly inclined from their axes at the operating angle 0 shown by the dashed line. The inclination is 2 to 2 when the operating angle θ is, for example, about 23 °.
It is about 3 °. Since this inclination is naturally allowed by the curvature of the circular arc portion 32a on the inner peripheral surface of the ring 32, it is possible to prevent the surface pressure at the contact portion between the leg shaft 22 and the ring 32 from becoming excessively high. In addition, FIG.
FIGS. 4A and 5C schematically show three leg shafts 22 of the tripod member 20 as viewed from the left side surface, and a solid line represents the leg shaft.

As the slide type constant velocity universal joint 51, a bar field type slide type constant velocity universal joint (double offset type constant velocity universal joint: DOJ) shown in FIG. 7 can be employed. This constant velocity universal joint includes an outer joint member 1 ′
, The inner joint member 2 ', the torque transmitting ball 3', and the cage 4 'as main components. The outer joint member 1 'has a cylindrical inner peripheral surface 1a',
In a ′, six axially extending guide grooves 1b ′ are formed at equal intervals in the circumferential direction. The inner joint member 2 'has a spherical outer peripheral surface 2a', and six axially extending guide grooves 2b 'are formed on the outer peripheral surface 2a' at equal intervals in the circumferential direction. A serration hole or a spline hole 2 for engaging with the intermediate shaft 20 in the form of a tooth is formed in the shaft center of the inner joint member 2 '.
c 'is formed. Guide groove 1b 'of outer joint member 1'
And the guide groove 2b 'of the inner joint member 2' make a pair to form six ball tracks, and one ball 3 'is incorporated in each ball track. All balls 3 '
Are held in the same plane by the cage 4 '. The center of the spherical surface of the inner peripheral surface 4a 'of the cage 4' and the center of the spherical surface of the outer peripheral surface 4b 'are offset by the same distance in the axial direction from the center of the pocket of the cage 4'.

FIG. 8 shows a Rebro-type constant velocity universal joint (LJ) as still another example of the slide type constant velocity universal joint 51. This constant velocity universal joint has an outer joint member 1 "having six guide grooves 1b" on an inner peripheral surface 1a ", and an outer joint member 1" having an outer peripheral surface 2a ".
The inner joint member wheel 2 ″ having the two guide grooves 2 b ″, the pair of outer joint member guide grooves 1 b ″, and the inner joint member guide grooves 2 b ″ formed in a pair of ball tracks formed by the paired inner joint member guide grooves 2 b ″ Ball 3 ", a cage 4" for holding all the balls 3 "in the same plane, an end plate 5 attached to one end of the joint, and a dust seal 7 attached to the other end of the joint. Outer joint member 1 "
And the output shaft S of the differential 52 are fastened by bolts 8 with the end plate 5 sandwiched therebetween. The inner joint member 2 "is connected to the intermediate shaft 50 by a serration hole or a spline hole 2c". The guide groove 1b "of the outer joint member 1" and the guide groove 2b "of the inner joint member 2" are inclined at a predetermined angle with respect to the axis in directions opposite to each other. The universal joint is also called a cross groove type.

[0045]

The present invention adopts a constant velocity universal joint at both ends of an intermediate shaft, a constant velocity universal joint using eight balls on a fixed side, and a constant velocity universal joint using six balls on a slide side. Since a universal joint or a combination employing a constant velocity universal joint using three rollers is used, resonance (resonance) of the drive shaft due to at least the second moment is less likely to occur. As a result, generation of abnormal noise in the vehicle interior is suppressed, and it is possible to contribute to improvement in NVH performance.

For the fixed type constant velocity universal joint, the ratio r1 (= r) of the pitch circle diameter (PCDBALL) to the diameter (DBALL) of the ball
PCDBALL / DBALL), outer diameter of outer joint member (DOUTER
) And pitch circle diameter of tooth profile of inner joint member (PCDSERR)
By setting the ratio r2 (= DOUTER / PCDSERR) within the numerical range exemplified for the embodiment, the size of the constant velocity universal joint can be reduced, so that the drive shaft can be made compact and the vehicle weight can be reduced. This is advantageous for weight reduction and fuel economy. Further, by making the intermediate shaft hollow, further weight reduction is realized.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a drive shaft.

FIG. 2A is a longitudinal sectional view of a Barfield type fixed constant velocity universal joint, and FIG. 2B is a transverse sectional view.

3A is a cross-sectional view of a tripod type constant velocity universal joint, FIG. 3B is a cross-sectional view perpendicular to a leg axis, and FIG. 3C is a cross-sectional view of a ring for explaining a contact ellipse. .

4A is a longitudinal sectional view of the constant velocity universal joint shown in FIG. 3 and shows a state where an operating angle is set, and FIG. 4B is a schematic side view of the tripod member in FIG.

5 (A) is an end view of a tripod type constant velocity universal joint with a partial cross section, FIG. 5 (B) is a cross section perpendicular to the leg axis in FIG. 5 (A), and FIG. It is a longitudinal section of a joint and shows the state where the operation angle was taken.

FIG. 6 is an enlarged sectional view of the ring in FIG. 5;

FIG. 7 is a longitudinal sectional view of a double offset type sliding constant velocity universal joint.

FIG. 8 is a longitudinal sectional view of a cross groove type constant velocity universal joint.

FIG. 9 is a longitudinal sectional view showing a power transmission device of an automobile.

FIG. 10 is a longitudinal sectional view of the drive shaft in FIG.

FIG. 11 is a vector diagram illustrating a bending moment.

FIG. 12 is a composite diagram of a vibration component.

FIG. 13 is a composite diagram of a vibration component.

[Explanation of symbols]

 1, 1 ', 1 "outer joint member 2, 2', 2" inner joint member 3, 3 ', 3 "ball 4, 4', 4" cage 10 outer joint member 14 roller guide surface 20 tripod member 22 leg shaft 32 Ring 34 Roller 36 Needle roller 50 Intermediate shaft 51 Sliding constant velocity universal joint 52 Differential 53 Fixed constant velocity universal joint 54 Drive wheel axle

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keisuke Sone 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, Japan (72) Inventor Ryo Nakagawa 1578 Higashikaizuka, Iwata City, Shizuoka Prefecture, F-term (reference) 3D042 AA06 AA08 AB01 DA05 DA12 DC01 3J033 AA10 BA02 BA07 BA13 BC10

Claims (10)

[Claims] 1. A drive shaft comprising an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. A fixed type constant velocity universal joint includes an outer joint member formed with eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface, and eight guide grooves extending in an axial direction on a convex spherical outer peripheral surface. The formed inner joint member, eight balls disposed on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member, and the balls in the same plane. An outer joint member formed with six guide grooves extending in the axial direction on a cylindrical inner peripheral surface, and a shaft on a convex spherical outer peripheral surface. Six guide grooves extending in the direction An inner joint member, six balls disposed on six ball tracks formed by a pair of guide grooves of the outer joint member and a guide groove of the inner joint member, and holding the balls in the same plane; A drive shaft comprising: a drive shaft; 2. A drive shaft comprising an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. A fixed type constant velocity universal joint includes an outer joint member formed with eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface, and eight guide grooves extending in an axial direction on a convex spherical outer peripheral surface. The formed inner joint member, eight balls disposed on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member, and the balls in the same plane. An outer joint member in which the slide-type constant velocity universal joint has six guide grooves inclined on an inner peripheral surface with respect to an axis, and an outer joint on an outer peripheral surface with respect to the axis. Tilt in the direction opposite to the guide groove of the member An inner joint member having six guide grooves formed therein, and six balls respectively arranged in six ball tracks formed by a pair of guide grooves of an outer joint member and a guide groove of an inner joint member. And a cage for holding the balls in the same plane. 3. A drive shaft comprising an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. A fixed type constant velocity universal joint includes an outer joint member formed with eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface, and eight guide grooves extending in an axial direction on a convex spherical outer peripheral surface. The formed inner joint member, eight balls disposed on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member, and the balls in the same plane. An outer joint member in which three track grooves having roller guide surfaces disposed circumferentially facing each other are formed, and the slide type constant velocity universal joint is radially protruded. Three legs Tripod member and the drive shaft, characterized in that it comprises a movable roller in the axial direction of the outer joint member along the rotatably supported on the trunnions said roller guide surfaces having. 4. A drive shaft comprising an intermediate shaft, a fixed type constant velocity universal joint attached to one end of the intermediate shaft, and a slide type constant velocity universal joint attached to the other end of the intermediate shaft. A fixed type constant velocity universal joint includes an outer joint member formed with eight guide grooves extending in the axial direction on a concave spherical inner peripheral surface, and eight guide grooves extending in an axial direction on a convex spherical outer peripheral surface. The formed inner joint member, eight balls disposed on eight ball tracks formed by a pair of guide grooves of the outer joint member and the guide grooves of the inner joint member, and the balls in the same plane. An outer joint member in which three track grooves having roller guide surfaces disposed circumferentially facing each other are formed, and the slide type constant velocity universal joint is radially protruded. Three legs And a roller rotatably supported by the leg shaft and movable in the axial direction of the outer joint member along the roller guide surface, wherein the tripod member is rotatable between the leg shaft and the roller. With a ring interposed, the inner peripheral surface of the ring is formed in an arc-shaped convex cross-section, and the outer peripheral surface of the leg shaft is straight in a vertical cross-section, and is orthogonal to the joint axis in a cross-section. 4. The drive shaft according to claim 3, wherein the drive shaft contacts the inner circumferential surface of the ring in a direction and forms a clearance between the inner circumferential surface of the ring and the axial direction of the joint. 5. The drive shaft according to claim 4, wherein the cross section of the leg shaft has a substantially elliptical shape whose major axis is perpendicular to the axis of the joint. 6. The drive shaft according to claim 4, wherein the generatrix of the inner peripheral surface of the ring is constituted by a circular arc portion at a central portion and a relief portion at both ends. 7. The drive shaft according to claim 4, wherein a plurality of rolling elements are arranged between the ring and the roller to make the ring and the roller relatively rotatable. 8. The drive shaft according to claim 7, wherein the rolling elements are needle rollers. 9. An outer peripheral surface of the roller is formed in a spherical shape,
The drive shaft according to any one of claims 3 to 8, wherein the drive shaft is in angular contact with a roller guide surface of the outer joint member. 10. The drive shaft according to claim 1, wherein the intermediate shaft is hollow.