JP3115557B2 - Constant velocity universal joint - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a constant velocity universal joint used as a component of a vehicle power transmission device.

[0002]

2. Description of the Related Art In general, a propeller shaft for a vehicle is provided with a universal joint, but when the connecting angle between the driving side rotating member and the driven side rotating member is large, a double cardan type constant velocity universal joint is mainly used. Have been. The double cardan constant velocity universal joint maintains constant velocity between the rotating members by connecting two hook joints. However, since the double cardan constant velocity universal joint has a structure in which two hook joints are connected,
There is a problem that the manufacturing cost is high and the weight increases. Therefore,
Recently, a barfield type constant velocity universal joint having a simple structure and light weight has been widely used.

[0003] An example of a propeller shaft having a barfield type constant velocity universal joint as described above is disclosed in JP-A-7-91.
458. The Barfield constant velocity universal joint described in this publication includes an inner race,
And an outer race arranged outside the inner race. A plurality of inner grooves are formed on the outer peripheral surface of the inner race, and a plurality of outer grooves are formed on the inner peripheral surface of the outer race. One inner groove and one outer groove constitute one set, and a ball is held for each set.

[0004] Further, a bisecting surface is set which bisects the angle formed by the first axis of the inner race and the second axis of the outer race. The center of curvature of the inner groove in the plane including the first axis and the center of curvature of the outer groove in the plane including the second axis are offset on both sides of the bisector. Furthermore, an annular retainer is arranged between the inner race and the outer race. Each ball is held by the holder.

When the propeller shaft is mounted, the inner race is connected to the transmission and the outer race is connected to the differential. The first axis of the inner race intersects with the second axis of the outer race, and a predetermined connection angle is set.

According to the above-described propeller shaft, the torque output from the transmission is transmitted to the differential via the inner race, the ball, and the outer race. Here, during transmission of torque by the Barfield constant velocity universal joint, each ball moves in the inner groove and the outer groove in a direction orthogonal to the bisecting plane, and the center of each ball is divided into two equal parts. The inner race (driving-side rotating member) and the outer race (driven-side rotating member) are maintained on the surface, and the uniform speed is maintained.

[0007]

However, in the Barfield constant velocity universal joint described in the above publication, the center of curvature of the inner groove and the center of curvature of the outer groove are offset on both sides of the bisector. . That is, the contact point at which the ball contacts the inner surface of the inner groove and the contact point at which the ball contacts the inner surface of the outer groove are offset to one of the bisectors. Therefore, at the time of transmitting the torque, two forces (loads) from each contact point toward the center of the ball act. Then, a resultant force in a direction orthogonal to the bisector is generated by the two forces, and each ball is pressed in that direction.

[0008] Then, the pressing force of each ball is transmitted to the retainer, the inner peripheral surface of the retainer is pressed against the outer peripheral surface of the inner race, and the outer peripheral surface of the retainer is pressed against the inner peripheral surface of the outer race. . For this reason, a contact portion between the retainer and the inner race and the outer race generates heat. As a result, there is a possibility that fatigue, wear or peeling may occur in these contact portions, and there is a possibility that the durability and torque transmitting function of the Barfield constant velocity universal joint may be reduced.

The present invention has been made in view of the above circumstances, and minimizes a force acting on a retainer from a ball and pressing the retainer in a direction perpendicular to a bisecting plane. It is an object of the present invention to provide a constant velocity universal joint that can perform the above operation.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides an inner race having a plurality of inner grooves formed on an outer peripheral surface, an inner race disposed outside the inner race, and an inner race. An outer race in which a plurality of outer grooves are formed on a surface; a plurality of balls arranged in each set with the one inner groove and the one outer groove as one set; and an inner race and the outer race. An annular retainer that is disposed between the two and that holds the center of the ball on a bisecting surface that divides the angle between the first axis of the inner race and the second axis of the outer race into two equal parts, A center of curvature of an arc-shaped portion of the inner groove in a plane including the first axis;
The center of curvature of the arc-shaped portion of the outer groove in a plane including the axis is offset to both sides of the bisecting surface, so that the ball and the arc-shaped portion of the inner groove come into contact with each other. and contact between the ball and an arc-shaped portion of the outer groove and a second contact point that contacts,
In the constant velocity universal joint is offset to one of the bisector plane, all in the circumferential direction before Symbol inner race
First contact point for transmitting torque between the arc-shaped portion of the Lee runner groove and the ball of Te is, in a direction toward the bisector plane, all i in the circumferential direction before Symbol inner race <br /> at least a portion of the arc-shaped portion of the runner groove with tilting in a spiral direction, in the circumferential direction before Symbol outer race
The second contact point for transmitting torque between the arcuate portions of all of the A Sauter groove and the ball definitive is, toward the said bisector plane, in the circumferential direction before Symbol outer race
Characterized in that is tilted at least a portion of the arc-shaped part of all A Sauter grooves in a spiral direction.

According to the present invention, the transmission of torque by the ball is performed between the inner race and the outer race. Further, the center of each ball is held on a bisecting plane, and the inner race and the outer race rotate at a constant speed.

On the other hand, since the centers of curvature of the arc-shaped portions of the inner groove and the outer groove are offset to both sides of the bisector, the contact point between the ball and the inner groove and the outer groove is also shifted from the bisector. Offset. For this reason, when torque is transmitted between the inner race and the outer race via the ball, the first contact point between the ball and the arc-shaped portion of the inner groove and the ball and the arc-shaped portion of the outer groove are formed. At the second contact point, two loads are generated toward the center of the ball.

In the present invention, at least a part of the arc-shaped portion of the inner groove is inclined in the helical direction in a direction in which the first contact point approaches the bisector, and the second contact point approaches the bisector. At least a part of the arc-shaped portion of the outer groove is inclined in the helical direction. For this reason, the angle on the acute angle side between each load vector and the bisecting plane is as small as possible, and the resultant force of the two loads, that is,
The pressing force for pressing in the direction orthogonal to the equal plane is reduced.
Therefore, heat generation at the contact portion between the retainer and the inner race and the outer race is suppressed.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the constant velocity universal joint of the present invention is used as a component of a propeller shaft will be described in detail with reference to the accompanying drawings. FIG. 1 is a sectional view showing an assembled state of a barfield type constant velocity universal joint 1 according to one embodiment of the present invention. In the technical field of constant velocity universal joints, a bar field type constant velocity universal joint may be called a Zeppa type constant velocity universal joint. The barfield type constant velocity universal joint 1 includes an inner race 2 and an outer race 3, six balls 4, and an annular retainer 5. Hereinafter, the configuration of these components and the positional relationship between these components and other components will be specifically described.

The inner race 2 is spline-fitted to one end of the shaft 6, and the inner race 2 is positioned in the longitudinal direction of the shaft 6 by a snap ring (not shown). With the above configuration, the inner race 2 is rotatable about the first axis A1. The shaft 6 is a differential (not shown)
Connected to the side.

The outer race 3 is formed in a cylindrical shape,
The outer race 3 is arranged outside the inner race 2. A boss 7 is formed integrally with the outer race 3 at an end of the outer race 3 opposite to the shaft 6, and a shaft 8 is provided at an outer end of the boss 7. The shaft 8 is connected to a transmission (not shown). With the above configuration, the outer race 3 is rotatable about the second axis B1.

When the propeller shaft having the above-structured barfield type constant velocity universal joint 1 is mounted on a vehicle, a predetermined connection angle is set between the first axis A1 and the second axis B1. In the first, for convenience, the first
The axis A1 and the second axis B1 are shown as being set substantially linearly.

FIG. 2 is a plan view of the inner race 2, and FIG. 3 is a side view of the inner race 2. Six inner grooves 9 are formed on the outer periphery of the inner race 2 at equal intervals in the circumferential direction. As shown in FIG. 1, the first axis A1
The cross-sectional shape of each of the inner grooves 9 in a plane including is formed in an arc shape that protrudes toward the outer peripheral side of the inner race 2 in the entire length direction. The center of curvature D1 of the arc-shaped portion of each inner groove 9 is defined by the first axis A
1, a bisecting plane C1 and a first axis A1
Is offset to one of the intersections E1. The shape of the side surface of each inner groove 9 is substantially semicircular.

All of the inner grooves 9 are formed in the lengthwise direction of the inner race 2 so as to be inclined in the helical direction on the outer periphery of the inner race 2. Specifically, the center line F1 in the width direction of each inner groove 9 is formed linearly, and the center line F1 is inclined by an angle α1 with respect to the first axis A1. In addition,
The inclination direction of each inner groove 9 will be described later.

On the other hand, six outer grooves 10 are formed on the inner periphery of the outer race 3 at equal intervals in the circumferential direction. Each of the outer grooves 10 has a cross-sectional shape in a plane including the second axis B <b> 1, and the entire length thereof is formed in an arc shape protruding toward the outer peripheral side of the outer race 3. Then, in the plane including the second axis B1, the center of curvature G1 of the arc-shaped portion of each outer groove 10 is offset to the other of the intersection E1 between the bisector C1 and the second axis B1. That is, the center of curvature D1 and the center of curvature G1 are arranged on both sides of the intersection E1 between the first axis A1 and the second axis B1. Further, the side surface shape of each outer groove 10 is configured to be substantially semicircular.

FIG. 4 is a conceptual plan view showing the structure of the outer race 3, and FIG. 5 is a side view of the outer race 3 viewed from the opening end side. All of the outer grooves 10 are formed so as to be entirely spirally inclined in the inner circumference of the outer race 3 in the length direction. Specifically, the center line H1 in the width direction of each outer groove 10 is inclined by an angle β1 with respect to the second axis B1. The inclination direction of each outer race 10 and the inclination direction of each inner groove 9 are set opposite to each other. In addition, the inclination direction of each outer race 10 will be described later.

As shown in FIG. 1, the outer peripheral surface of the retainer 5 is curved in a direction including the central axis (not shown) so as to protrude outward. That is, the shape of the outer spherical surface (outer peripheral surface) 5A of the retainer 5 has a shape that approximates the inner spherical surface 3A of the outer race 3. In the assembled state of the Barfield constant velocity universal joint 1, the outer spherical surface 5A and the inner spherical surface 3A are in close contact with each other. In addition, the shape of the inner spherical surface (inner peripheral surface) 5B of the retainer 5 is curved in a direction protruding to the outer peripheral side in a plane including the central axis. That is, the inner spherical surface 5B of the retainer 5 has a shape approximating the outer spherical surface 2A of the inner race 2. Then, in the assembled state of the Barfield constant velocity universal joint 1, the inner spherical surface 5B and the outer spherical surface 2A are in close contact with each other.

The retainer 5 is provided with six ball retaining holes 11 at equal intervals in the circumferential direction, penetrating the retainer 5 in the thickness direction. Here, in a plane orthogonal to the bisector C1, the shape of each ball holding hole 11 is configured to be substantially square. Each ball 4 is arranged in each ball holding hole 11, and each inner groove 9 and each outer race 10 are set as one set, and each set of balls 4 is held.

When torque is transmitted between the outer race 3 and the inner race 2 via the ball 4, the ball 4 moves in the inner groove 9 and the outer groove 10 in the length direction. Accordingly, the contact point between the ball 4 and the inner surface of the inner groove 9 is three-dimensionally displaced.
This contact point moves, for example, along a trajectory indicated by a dashed line in FIG. In this embodiment, the center of curvature D1 and the center of curvature G1 are offset on both sides of the bisector C1. For this reason, when the ball 4 is at a predetermined position in the length direction of the inner groove 9, the first contact points J1 and J2 between the inner surface of the inner groove 9 and the ball 4 are divided into two bisecting surfaces C1.
Is set to a position offset from.

The contact point between the ball 4 and the inner surface of the outer groove 10 is also three-dimensionally displaced, and this contact point moves, for example, along a trajectory shown by a chain line in FIG. In this embodiment, the center of curvature D1 and the center of curvature G1 are offset on both sides of the bisector C1. For this reason, when the ball 4 and the outer groove 10 are located at predetermined positions in the longitudinal direction, the second surface between the inner surface of the outer groove 10 and the ball 4
The contact points K1 and K2 are set at positions offset from the bisector C1.

Here, the inclination direction of the outer groove 10 and the inner groove 9 will be described. In the Barfield constant velocity universal joint 1, the outer race 3 is connected to the transmission side, and the inner race 2 is connected to the differential side. Therefore, as shown in FIG. 4, when the outer race 3 rotates in the direction of the arrow, the torque of the outer race 3 is transmitted to the inner race 2 via the ball 4. At the time of this torque transmission, a load N1 from the inner surface of the outer groove 10 to the center M1 of the ball 4 acts on the second contact point K2. At the first contact point J1, a load (reaction force) N2 from the inner surface of the inner groove 6 toward the center M1 of the ball 4 acts.

In this embodiment, from the state where the second center line H1 and the second axis line B1 are set on a straight line, the second contact point K2 moves in the direction approaching the bisecting plane C1. The line H1 is inclined by an angle β1 with respect to the second axis B1. In other words, the angle on the acute angle side between the vector of the load N1 and the bisector C1 becomes smaller in the direction in which the angle becomes smaller.
The center line H1 is inclined. That is, the outer groove 10
Is set to a predetermined depth, is curved in a plane including the second axis B1, and is further inclined in a predetermined direction to give the outer groove 10 a three-dimensional shape. .

Further, in this embodiment, from the state where the first center line F1 and the first axis A1 are set on a straight line,
The first center line F1 is inclined by an angle α1 with respect to the first axis A1 in a direction in which the first contact point J1 approaches the bisector C1. In other words, the vector of the load N2 and the bisector C
The first center line F1 is inclined in such a direction that the angle on the acute angle side with 1 becomes smaller. That is, the inner groove 9 is set to a predetermined depth, is curved in a plane including the first axis A1, and is further inclined in a predetermined direction, so that the inner groove 9 has a three-dimensional shape. Is given.
Thus, the inner groove 9 and the outer groove 10 are inclined in opposite directions.

On the other hand, one end of a bellows-shaped boot (not shown) is fixed to the opening of the outer race 3, and the other end of the boot is fixed to the shaft 6. The interior space of the Barfield constant velocity universal joint 1 is sealed by the boot, and grease (not shown) is sealed in the sealed space.

The inner race 2 and the outer race 3 are made of a material such as carbon steel or chrome steel. The retainer 5 is made of a material such as chrome steel, and the ball 4 is made of a material such as bearing steel. Further, the shaft 6 is made of a material such as carbon steel, carbon steel pipe, or boron steel. The shaft 6, the inner race 2, the outer race 3, the ball 4, and the material constituting the retainer 5 are all subjected to heat treatment. That is, induction hardening is applied to the medium carbon steel, and carburizing and quenching is applied to the low carbon steel. In this way, by hardening the surface of various materials, each component has the necessary strength for transmitting the torque.

Next, the operation of transmitting torque by the Barfield constant velocity universal joint 1 shown in FIG. 1 will be described. When the propeller shaft having the Barfield constant velocity universal joint 1 is attached to a vehicle, a predetermined connection angle is set between the first axis A1 and the second axis B1. Then, the torque output from the transmission is transmitted to the Barfield constant velocity universal joint 1 of the propeller shaft, and then transmitted differentially. In this way,
While the propeller shaft rotates at high speed, the torque transmitted to the outer race 3 is transmitted to the inner race 2 via the ball 4.

Then, a Barfield type constant velocity universal joint 1
In, the center of curvature D1 of the inner groove 9 and the center of curvature G1 of the outer groove 10 are offset with respect to the intersection E1, and each ball 4 is held by the holder 5. Therefore, the center M1 of each ball 4 moves on a circular locus along the bisector C1. As a result, constant rotation of the outer race 3 and the inner race 2 is maintained.

It is to be noted that, with the change in the rotational phase of the outer race 3 and the inner race 2, the retainer 5 is deflected about the intersection E1 with respect to the outer race 3 and the inner race 2. Therefore, the inner spherical surface 3A of the outer race 3 and the outer spherical surface 5A of the retainer 5 slide,
The outer spherical surface 2A of the inner race 2 and the inner peripheral surface 5 of the cage 5
B slides. These sliding parts (heat generating parts) and other sliding parts are cooled and lubricated by grease.

Outer race 3 and inner race 2
During the rotation of, each ball 4 moves in each inner groove 9 and each outer groove 10 in the length direction thereof. By the way, in the Barfield constant velocity universal joint 1, the center of curvature D1 of the arc-shaped portion of the inner groove 9 and the center of curvature G1 of the arc-shaped portion of the outer groove 10 are offset on both sides of the bisector C1. The first contact point J1 between the ball 4 and the inner surface of the inner groove 9 and the second contact point K2 between the ball 4 and the inner surface of the outer groove 10 are also offset from the bisector C1.

For this reason, the outer race 3 to the ball 4
When the torque is transmitted to the inner race 2 through the second contact point, a load N1 toward the center M1 of the ball 4 acts on the second contact point K2 between each ball 4 and the inner surface of the outer groove 10. At the first contact point J1 between each ball 4 and the inner surface of the inner groove 9, a load N2 toward the center M1 of the ball 4 acts.

In this embodiment, the first contact point J1
, The inner groove 9 is inclined in a direction approaching the bisector C1, and the outer groove 10 is inclined in a direction in which the second contact point K2 approaches the bisector C1. Therefore, at the first contact point J1 and the second contact point K2, the two loads N1, N2 directed toward the center M1 of the ball 4
And the angle on the acute angle side between the vector and the bisecting plane C1 becomes as small as possible. As a result, the resultant force N3 of the two loads N1 and N2, that is, the pressing force for pressing the retainer 5 in a direction orthogonal to the bisector C1 is reduced.

Thus, the contact portion P1 between the inner spherical surface 5B of the retainer 5 and the outer spherical surface 2A of the inner race 2, and the outer spherical surface 5A of the retainer 5 and the inner spherical surface 3 of the outer race 3
The frictional force (in other words, the amount of work) of the contact portion P2 with A is reduced, and the heat generation of the contact portions P1 and P2 is suppressed. Therefore, the contact portions P1 and P2 are less likely to be fatigued, worn or peeled off, and the durability and torque transmission function of the barfield type constant velocity universal joint 1 are improved.

According to the test conducted by the present applicants,
When the bar field type constant velocity universal joint of the comparative example and the bar field type constant velocity universal joint 1 of the example in which the outer groove and the inner groove are not inclined are compared, the work amount is about 2/3. It has been confirmed that it is reduced.

Further, since the heat generation at the contact portions P1 and P2 is suppressed, the size (specifically, the outer diameter) of the components such as the inner race 2, the outer race 3, and the retainer 5 is determined.
It is possible to transmit the required torque even when the size of the device is reduced. Therefore, downsizing and weight reduction of the Barfield constant velocity universal joint 1 itself can be realized, and a gap between components disposed around the Barfield constant velocity universal joint 1 can be narrowed. improves.

Further, since the heat generation at the contact portions P1 and P2 is suppressed, the selection range of the components of the grease sealed in the inside of the Berfield type constant velocity universal joint 1 and the material of the boot is widened. Furthermore, since the heat generation at the contact portions P1 and P2 is suppressed, the connection angle between the outer race 3 and the inner race 2 can be set as large as possible. Therefore, it becomes possible to apply the Barfield type constant velocity universal joint 1 to a vehicle or an installation site where the connection angle between the outer race 3 and the inner race 2 needs to be set to be larger than a predetermined value, Its application will be expanded to facilitate mass production.

In the present invention, it is also possible to employ a configuration in which a part of the length of the outer groove is inclined in the spiral direction and a part of the length of the inner groove is inclined in the spiral direction. .

The present invention is also applicable to a constant velocity universal joint having a configuration called an undercut free type constant velocity universal joint. In this undercut-free type constant velocity universal joint, an arc-shaped portion is formed in a part of the inner groove in a plane including the first axis, and a portion other than the arc-shaped portion in the inner groove is configured to be parallel to the first axis. Have been.
Further, an arc-shaped portion is formed in a part of the outer groove in a plane including the second axis, and a portion other than the arc-shaped portion in the outer groove is configured to be parallel to the second axis.

Further, the constant velocity universal joint of the present invention can be applied to a propeller shaft having a configuration in which an inner race is connected to a transmission side and an outer race is connected to a differential side. In this case, the inclination direction of the inner groove of the inner race and the inclination direction of the outer groove of the outer race are set opposite to those in the illustrated embodiment. Furthermore, the constant velocity universal joint of the present invention can be applied to a drive shaft.

[0044]

As described above, according to the present invention, when torque is transmitted between the inner race and the outer race and the ball, the first contact point and the second contact point move toward the center of the ball. Two loads act. here,
At least a part of the arc-shaped portion of the inner groove is inclined in the helical direction so that the first contact point approaches the bisector, and the arc shape of the outer groove is inclined in the direction where the second contact point approaches the bisector. At least a portion of the portion is helically inclined.

For this reason, the angle of the acute angle between each load vector and the bisecting plane is made as small as possible, and the resultant force of the two loads, that is, the cage is moved in the direction orthogonal to the bisecting plane. The pressing force for pressing is reduced. Therefore, heat generation at the contact portion between the retainer and the inner race and the outer race is suppressed, and the contact portion is less likely to be fatigued, worn or peeled, and the durability and torque transmission function of the constant velocity universal joint are improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a barfield type constant velocity universal joint according to an embodiment of the present invention.

FIG. 2 is a plan view of an inner race used in the Barfield constant velocity universal joint shown in FIG.

FIG. 3 is a side view of the inner race shown in FIG. 2;

FIG. 4 is a plan view of an outer race used in the Barfield constant velocity universal joint shown in FIG. 1;

FIG. 5 is a side view of the outer race shown in FIG. 4;

[Explanation of symbols]

2 inner race, 3 outer race, 4 ball, 5 cage, 9 inner groove, 10 outer groove, C1 bisected surface, D1, G1 center of curvature,
J1: first contact point, K2: second contact point.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Gojo Sugiura 41-1, Chukumi Yokomichi, Nagakute-cho, Aichi-gun, Aichi Prefecture Inside Toyota Central R & D Laboratories, Inc. (56) References JP-A-6-50351 (JP, A) JP-A-59-158717 (JP, U) JP-B-52-20625 (JP, B1) (58) Fields investigated (Int. Cl. ⁷ , DB name) F16D 3/224

Claims (1)

(57) [Claims] An inner race having a plurality of inner grooves formed on an outer peripheral surface thereof; an outer race having a plurality of outer grooves formed on an inner peripheral surface disposed outside the inner race; A plurality of balls arranged in each set with the inner groove and the one outer groove as one set, and a plurality of balls arranged between the inner race and the outer race, and a first axis of the inner race and the outer race; An annular retainer for holding the center of the ball on a bisecting surface that divides the angle between the inner axis and the second axis into two equal parts, wherein the inner groove has an arc-shaped portion in a plane including the first axis. The center of curvature and the center of curvature of the arc-shaped portion of the outer groove in a plane including the second axis are offset on both sides of the bisecting plane, so that the ball and A first contact point of the arc-shaped portion of the inner groove abuts a second abutment point between the ball and an arc-shaped portion of the outer groove abuts is offset to one of the bisector plane in the constant velocity universal joint, a first contact point for transmitting torque between the arcuate portions of all of Lee runner grooves in the circumferential direction before Symbol inner race and said ball is in a direction approaching to the bisector plane , before heard
With tilting the at least a portion of the arc-shaped portion of all Lee runner grooves in a helical direction in the circumferential direction of the N'naresu, arc-shaped part of all A Sauter grooves in the circumferential direction before Symbol outer race and between the balls the second contact point for transmitting torque between the, in the direction approaching to the bisector plane, before Kia
Constant velocity universal joint, characterized in that at least a portion of the arc-shaped part of all A Sauter grooves in the circumferential direction of the Utaresu is inclined in a spiral direction.