JP2006266368A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant velocity universal joint for minimizing loads on ball grooves of inner and outer rings and on a pocket of a cage in a 0-deg phase. <P>SOLUTION: The fixed type constant velocity universal joint comprises the inner and outer rings 20, 10 having ball grooves 24, 24 in tapered shape to which cage offset (f) is only imparted instead of track offset (F). A taper angle α is 12-deg or smaller. A value f/PCR for the ratio of a cage offset amount f to PCR is within a range of 0-0.12 not including 0. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint. Constant velocity universal joints transmit torque at a constant angular speed by connecting the rotating shaft on the drive side and the rotating shaft on the driven side in the power transmission system of automobiles and various industrial machines. The slidable type allows angular displacement and axial displacement, whereas the fixed type allows only angular displacement.

  In general, a fixed type constant velocity universal joint includes an outer joint member that is coupled to a drive-side or driven-side shaft so as to be able to transmit torque, an inner joint member that is coupled to a driven-side or drive-side shaft so as to be able to transmit torque, and an outer joint A plurality of torque transmitting elements that transmit torque by being interposed between the member and the inner joint member, and a cage that holds the plurality of torque transmitting elements in a bisector of an angle formed by the drive shaft and the driven shaft. I have.

  In recent years, the wheelbase may be lengthened from the viewpoint of expanding the riding space of automobiles, but in order to prevent the vehicle turning radius from increasing accordingly, the fixed type used as a coupling joint for automobile drive shafts, etc. There is a demand for an increase in the steering angle of the front wheels by increasing the angle of the constant velocity universal joint.

As a fixed type constant velocity universal joint to meet the needs of high angle, it has been proposed to taper the ball groove of the outer joint member and the bottom of the ball groove of the inner joint member that constitute the track on which the torque transmitting element rolls. (For example, refer to Patent Documents 1 to 3).
JP 2001-153149 A JP 2001-304282 A JP 2001-349332 A

  In the fixed type constant velocity universal joint disclosed in Patent Documents 1 to 3, the angle of the ball is easily increased by making the ball grooves of the outer joint member and the inner joint member into a tapered shape. However, under the circumstances where the lighter and more compact design is the mainstream and the outer diameter of the outer joint member is regulated, the wall thickness of the outer joint member becomes thinner as the ball groove taper angle is further increased. The strength will be reduced.

  Further, in the fixed type constant velocity universal joint described in Patent Document 1, by increasing the cage offset, the load applied to the cage pocket is reduced at the phase where the ball jumps out most (phase angle 0 deg: see FIG. 3). However, in the conventional general constant velocity universal joint, the load of 0 deg phase increases as the angle increases.

  The main object of the present invention is to reduce the load applied to the ball grooves of the outer ring and the inner ring and the pocket of the cage in the 0 deg phase of the fixed type constant velocity universal joint as much as possible, and to easily increase the operating angle. Is to do.

  The present invention investigates factors that reduce the load applied to the ball grooves and cage pockets of the outer ring and the inner ring at 0 deg phase in the internal specifications of the high-angle fixed type constant velocity universal joint using internal force analysis. The problem is solved by optimally designing the range of each factor.

  That is, the fixed type constant velocity universal joint of the present invention includes an outer joint member in which a plurality of ball grooves extending in the axial direction to the opening end are formed on the inner spherical surface at equal intervals in the circumferential direction, and an outer spherical surface in the axial direction. A plurality of balls that transmit torque by interposing between a ball groove of an outer joint member and a ball groove of an inner joint member that form a pair, and an inner joint member in which a plurality of extended ball grooves are formed at equal intervals in the circumferential direction And a cage that is interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member, and that has a pocket for accommodating the ball in the circumferential direction, and has a groove on the open end of the ball groove of the outer joint member. The bottom has a taper shape that linearly expands toward the opening end, and the anti-opening end side groove bottom of the outer joint member of the ball groove of the inner joint member linearly expands toward the anti-opening end side. The outer tapered center and inner spherical center of the cage are jointed. The center of curvature of the ball groove of the outer joint member and the center of curvature of the ball groove of the inner joint member are offset from the joint center by the amount of the cage offset. It is characterized by being.

  When the center of curvature of the ball groove of the outer joint member is offset from the center of the inner spherical surface and the center of curvature of the ball groove of the inner joint member is offset from the center of the outer spherical surface by an equal distance in the axial direction (this offset) ), The ball groove becomes shallower toward the back side of the outer joint member. Therefore, when the operating angle is taken, the ball located at the innermost part of the outer joint member is placed on the shoulder of the ball groove. There is a risk of getting on. By eliminating this track offset, the ball groove does not become shallow even on the back side of the outer joint member, and therefore it is possible to suppress the climbing of the ball located at the innermost part of the outer joint member even when the operating angle is taken. it can.

  The invention of claim 2 is characterized in that, in the fixed type constant velocity universal joint of claim 1, the upper limit value of the taper angle of the ball groove of the outer joint member and the ball groove of the inner joint member is 12 °. While ensuring the strength and durability, which are the basic performances required in the past, studies were conducted using internal force analysis and finite element method (FEM) analysis, and the range of taper angles of the ball groove was narrowed down to the optimum setting. And the consistency with the evaluation result and analysis result of the sample which changed the taper angle was confirmed. By forming the ball groove in a tapered shape, the outer joint member can be easily increased without increasing the outer diameter of the outer joint member. In order to avoid reducing the strength and workability of the fixed type constant velocity universal joint, the influence and tendency of the ball groove being tapered in the internal specifications of this fixed type constant velocity universal joint are verified, and the upper limit is set as the optimum value of the taper angle. The value was defined as 12 °.

  According to a third aspect of the present invention, in the fixed type constant velocity universal joint according to the first or second aspect, an offset amount f of the outer spherical center and inner spherical center of the cage (this offset is referred to as a cage offset) and the outer side. The value f / PCR of the length PCR of the line segment connecting the center of curvature of the ball groove of the joint member or the center of the ball groove of the inner joint member and the center of the ball is greater than 0 and equal to or less than 0.12. It is characterized by. Since the cage offset amount f is related to the thickness difference in the longitudinal section of the cage, it is desirable to set the cage offset amount f in consideration of this point.

  For example, by setting the cage offset amount f large, there is an advantage that the strength can be improved by increasing the thickness of the cage on the opening end side of the outer joint member as in the invention of claim 4. Further, by increasing the thickness of the cage on the opening end side of the outer joint member, the ball that is about to jump out from the opening end of the outer joint member can be restrained by the cage when the operating angle is taken.

  However, if the cage offset amount f is too large, the amount of movement of the ball in the cage pocket in the circumferential direction increases, and it is necessary to increase the circumferential dimension of the cage pocket in order to ensure proper movement of the ball. The pillar portion of the cage becomes thin, and the strength surface becomes a problem. In addition, the thickness of the cage on the back side of the outer joint member, that is, the side opposite to the opening end is reduced, and the strength is a problem.

  Thus, it is not preferable that the cage offset amount f is excessive, and there exists an optimum range in which the significance of providing the cage offset amount f and the above-described strength can be balanced. However, since the optimum range of the cage offset amount f varies depending on the size of the joint, it needs to be determined in relation to the basic dimension representing the size of the joint. Therefore, if the value f / PCR of the ratio of the cage offset amount f to the length PCR of the line segment connecting the center of curvature of the ball groove of the outer joint member or the center of curvature of the ball groove of the inner joint member and the center of the ball is used. The cage offset amount f is preferably set so that f / PCR exceeds 0 and is 0.12 or less.

  If f / PCR is larger than 0.12, the above-mentioned problem in strength occurs. On the contrary, if it is smaller than 0, it is not meaningful to provide the cage offset amount f. That is, cage offset is one of the objectives to prevent the ball from jumping out of the cage pocket at a high operating angle, but the objective cannot be achieved within a range smaller than zero. Therefore, from the viewpoint of securing cage strength and durability, the range in which f / PCR exceeds 0 and is 0.12 or less is the optimum range of the cage offset amount f.

  The invention of claim 5 is characterized in that, in the fixed type constant velocity universal joint according to any one of claims 1 to 4, the finish forming of the ball groove of the outer joint member and the ball groove of the inner joint member is cold forging. To do. By finishing the tapered track groove by cold forging, the forging die can be easily pulled out, so that the workability of cold forging is good and the manufacturing cost can be reduced.

  According to the present invention, the following effects can be expected. The load applied to the ball groove of the outer ring in the 0 deg phase (hereinafter referred to as the outer ring track load) is reduced. The load applied to the ball groove of the inner ring in the 0 deg phase (hereinafter referred to as the inner ring track load) is reduced. At the 0 deg phase, the load on the outer ring opening end side of the cage pocket is reduced. In other words, the fixed type constant velocity universal joint is advantageous in operation in a higher angle region.

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

  The fixed type constant velocity universal joint shown in FIG. 1 includes an outer ring 10, an inner ring 20, a ball 30, and a cage 40 as main components. If the two shafts to be connected by the fixed type constant velocity universal joint are called a first rotating shaft and a second rotating shaft, the first rotating shaft is connected to the outer ring 10 and the second rotating shaft is connected to the inner ring 20. The torque is transmitted at a constant speed even when they are at an angle. 1 shows a state where the rotation axis X of the outer ring 10 and the rotation axis Y of the inner ring 20, that is, the operating angle θ is 0 °, and FIG. 3 shows a state where the operating angle θ is maximum (52 ° or more). It is shown.

  The outer ring 10 as an outer joint member includes a mouth portion 16 and a stem portion (not shown), and is coupled to the first rotating shaft so that torque can be transmitted at the stem portion. The mouse portion 16 has a bowl shape opened at one end, and a plurality of ball grooves 14 extending in the axial direction are formed at equal intervals in the circumferential direction on the concave spherical inner peripheral surface (hereinafter referred to as inner spherical surface) 12. It is. The ball groove 14 extends to the open end 18 of the mouse portion 16.

  An inner ring 20 as an inner joint member has a convex spherical outer peripheral surface (hereinafter referred to as an outer spherical surface) 22, and a plurality of ball grooves 24 extending in the axial direction are arranged on the outer spherical surface 22 at equal intervals in the circumferential direction. It is formed. The ball groove 24 is cut in the axial direction of the inner ring 20. The inner ring 20 has a spline hole 26 for coupling with the second rotating shaft so as to be able to transmit torque.

  The ball groove 14 of the outer ring 10 and the ball groove 24 of the inner ring 20 form a pair, and one ball 30 as a torque transmitting element is incorporated in a rollable manner, one on each track constituted by the pair of ball grooves 14, 24. It is. The ball 30 is interposed between the ball groove 14 of the outer ring 10 and the ball groove 24 of the inner ring 20 to transmit torque. Each ball 30 is accommodated in a pocket 46 disposed in the circumferential direction of the cage 40. The number of balls 30, and thus the number of ball grooves 14, 24, is arbitrary, but is 6 or 8 for example.

The cage 40 is slidably interposed between the outer ring 10 and the inner ring 20, is in contact with the inner spherical surface 12 of the outer ring 10 at the outer spherical surface 42, and is in contact with the outer spherical surface 22 of the inner ring 20 at the inner spherical surface 44. The center of curvature of the inner spherical surface 12 of the outer ring 10 and the center of curvature of the outer spherical surface 42 of the cage 40 coincide with each other, and are denoted by reference numeral O ₄ in FIG. Similarly, the center of curvature of the outer spherical surface 22 of the inner ring 20 coincides with the center of curvature of the inner spherical surface 44 of the cage 40, and is indicated by reference numeral O ₃ in FIG. In the drawing, the clearance between the inner spherical surface 12 of the outer ring 10 and the outer spherical surface 42 of the cage 40 and the clearance between the outer spherical surface 22 of the inner ring 20 and the inner spherical surface 44 of the cage 40 are exaggerated.

  The ball groove 14 of the outer ring 10 includes an arc portion 14a and a straight portion 14b. The arc portion 14a is positioned on the back side of the mouse portion 16, that is, on the side opposite to the opening end, and the linear portion 14b is positioned on the opening end 18 side. The ball groove 14 has a tapered shape with a taper angle α that linearly expands the groove bottom on the opening end 18 side toward the opening end 18.

  The ball groove 24 of the inner ring 20 includes an arc portion 14a and a straight portion 24b. The arc portion 24a is located on the opening end 18 side of the outer ring 10, and the straight portion 24b is located on the side opposite to the opening end. The ball groove 24 has a tapered shape with a taper angle α that linearly expands the groove bottom on the back side, that is, the opposite end surface side of the outer ring 10 toward the opposite end surface side.

In this embodiment, in order to obtain a structure that can have a large operating angle θ, the center of curvature O ₁ of the ball groove 14 of the outer ring 10 is set to the inner ring 20 with respect to the center O ₃ of the inner spherical surface 12 as shown in FIG. The curvature center O ₂ of the ball groove 24 is offset in the axial direction by an equal distance F from the center O ₄ of the outer spherical surface 22 (track offset).

Similarly, the center of curvature O ₃ of the outer spherical surface 42 of the cage 40 and the center of curvature O ₄ of the inner spherical surface 44 are offset in the axial direction by an equal distance f from the joint center O (cage offset).

  As shown in FIG. 3, when the rotation axis X of the outer ring 10 and the rotation axis Y of the inner ring 20 take a certain operating angle θ other than 0 °, a bisector of the angle θ formed by both the rotation axes X and Y If all the balls 30 are in the vertical plane, that is, the joint center plane P, the distances from the ball center to the two rotation axes X and Y are equal to each other. Transmission takes place. The intersection of the joint center plane P and the rotation axes X and Y is referred to as a joint center O. In the fixed type constant velocity universal joint, the joint center O is fixed regardless of the operating angle θ.

  The track formed by the ball groove 14 of the outer ring 10 and the ball groove 24 of the inner ring 20 that form a pair has a wedge shape that gradually expands from the back side of the mouth portion 16 of the outer ring 10 toward the opening end 18 side. . When the torque is transmitted with the joint at the operating angle θ, a thrust is applied to push the ball 30 from the narrow side to the wide side of the wedge-shaped track.

The cage offset amount f is set to be larger than the conventional one so that the ball 30 about to jump out of the open end 18 of the mouth portion 16 of the outer ring 10 can be restrained by the cage 40 when the maximum operating angle is taken. The radius of the center locus of the ball 30, that is, the length of the line segment connecting the center of curvature O ₁ of the ball groove 14 of the outer ring 10 or the center of curvature O ₂ of the ball groove 24 of the inner ring 20 and the center O _{5 of the} ball 30, is PCR Then, the value f / PCR of the ratio of the cage offset amount f to the PCR is set to be in the range of more than 0 and not more than 0.12.

  In the longitudinal section of the joint, the ball bottoms of the ball groove 14 of the outer ring 10 and the ball groove 24 of the inner ring 20 are tapered to increase the maximum operating angle, and in addition to the ball 30 in the ball groove 14 of the outer ring 10, Therefore, stable torque transmission between the outer ring 10 and the inner ring 20 is achieved. Further, since the track load and the pocket load of the phase (phase angle φ = 0 °) (see FIGS. 3 and 4) in which the ball 30 is most likely to jump out when the operating angle θ is taken, it is advantageous in a high angle region. is there. Here, the track load means a load received by the wall surfaces of the ball grooves 14 and 24 from the ball 30 in contact. The pocket load means a load that the wall surface of the pocket 46 receives from the contacting ball 30.

  Since the outer spherical surface 42 of the cage 40 is contact-guided to the inner spherical surface 12 of the outer ring 10 and the inner spherical surface 44 of the cage 40 is contact-guided to the outer spherical surface 22 of the inner ring 20, the cage 40 and the outer ring 10 or A spherical force (force that pushes the spherical surfaces against each other) acts between the inner ring 20, but the maximum value of the spherical force is reduced, leading to suppression of heat generation inside the joint. Furthermore, since the forging die has a shape that can be easily removed, workability by cold forging is good, and the manufacturing cost can be reduced.

  By making the groove bottoms of the ball grooves 14 and 24 of the outer ring 10 and the inner ring 20 into a tapered shape, the influence on the internal force consisting of the aforementioned track load, pocket load and spherical force and its tendency are verified, and the finite element method ( FEM) was performed, and the range of the taper angle α was narrowed down and optimally set. First, the tendency as shown in Table 1 is recognized in the internal force by increasing the taper angle α. In Table 1, the phase in which the ball 30 is most likely to jump out (phase angle φ = 0 °) and the phase of the ball 30 at which the internal force is maximum are verified. Further, the fluctuation range of the spherical force means a difference between the maximum value and the minimum value of the spherical force.

  As is clear from Table 1, when the taper angle α is increased, the maximum value of the pocket load increases. However, by increasing the cage offset amount f and increasing the wall thickness of the cage 40, the outer ring 10 and the cage 40 can be increased. Since strength can be secured, there is no problem.

  Next, a finite element method (FEM) analysis was performed to determine the upper limit value of the taper angle α. When the taper angle α is increased, the internal force (track load and pocket load) is reduced at the phase (phase angle φ = 0 °) in which the ball 30 is most likely to jump out, which is advantageous in terms of strength. Since the thickness of the open end 18 is small, the stress value generated in the ball groove 14 is converted into joint strength to confirm the tendency. The result is as shown in FIG. As is apparent from the figure showing the relationship of the joint strength to the taper angle α (deg), the joint angle is less than the required strength when the taper angle α is 12.9 °. Was defined as 12 °.

  In the above-described embodiment, the case where the track offset is provided is illustrated, but the track offset may not be provided. In other words, when the track offset is provided, the arc portion 14a located on the back side of the mouse portion 16 in the ball groove 14 of the outer ring 10 becomes shallower toward the back side. There is a possibility that the ball 30 located at the innermost part of the ball 14 rides up. Therefore, by setting the track offset amount to 0, the arc portion 14a located on the back side of the mouse portion 16 in the ball groove 14 of the outer ring 10 has a uniform depth. It is possible to suppress the riding of the ball 30 located at the innermost position of the ball groove 14.

  The results of the internal force analysis performed by varying each factor of the track offset amount F, the cage offset amount f, and the taper angle α will be described below. Here, with respect to the track offset, the track offset amount F = 0, that is, “no track offset” is set in consideration of the characteristics of the ultra-high angle fixed type constant velocity universal joint in which the allowable load torque does not drop even when entering the high angle region. The cage offset should be as small as possible from the viewpoint of internal force. However, to ensure the function of the joint, a certain amount of cage offset must be provided, so that 0 ≦ f / PCR ≦ 0.150 is varied. It was. The taper angle α was varied in the range from 0 deg to 12 deg.

  If f = 0 (f / PCR = 0), the track load and the pocket load in the 0 deg phase become zero when the taper angle α is 1.1 deg or more.

  On the other hand, when the taper angle α = 12 deg, the track load and the pocket load in the 0 deg phase become zero when f = 3.94 (f / PCR = 0.114) or less.

  That is, if the relationship between the cage offset amount f and the taper angle α is set within the hatched region in FIG. 6, the track load and the pocket load in the 0 deg phase become zero. Here, FIG. 6 is plotted based on data calculated by internal force analysis, and the horizontal axis represents the taper angle α (deg) and the vertical axis represents f / PCR.

As a result, the internal specifications that are advantageous in a higher angle operating range by reducing the load applied to the 0 deg phase as much as possible are as follows.
Track offset: None Cage offset amount f: 0 <f / PCR ≦ 0.12
Taper angle α: 1deg ≦ α ≦ 12deg

  In this embodiment, while the load at the 0 deg phase is reduced, the peak load is larger than that of the conventional constant velocity universal joint. Therefore, in order to ensure strength, the thick portion of the cage 40 is used as the outer ring. 10 is preferably arranged toward the opening end 18 side.

The track load and pocket load at 0 deg phase were calculated for the fixed type constant velocity universal joint according to the present invention (Example) and the conventional fixed type constant velocity universal joint (Comparative Example) according to the present invention whose dimensions were set as described above. Was as shown in FIG. From the figure, it can be seen that in the example, both the track load and the pocket load are reduced by 80% or more compared to the comparative example. In addition, the EWS internal force calculation result (T = T100 (462.6 Nm), θ = 46.5 deg) at this time is as shown in Table 2.

It is a longitudinal cross-sectional view of the fixed type constant velocity universal joint which shows embodiment of this invention. It is a principal part enlarged view of FIG. It is a longitudinal cross-sectional view which shows the state which the joint of FIG. 1 took the maximum operating angle. It is a cross-sectional view of a cage containing a ball. It is a diagram which shows the taper angle of a ball groove, and the relationship between joint strength. It is a diagram which shows the relationship between the taper angle of a track | truck, and f / PCR. It is a diagram which shows the 0deg phase load at the time of a basic torque load.

Explanation of symbols

10 outer ring 12 inner spherical surface 14 ball groove 16 mouse part 18 open end 20 inner ring 22 outer spherical surface 24 ball groove 26 spline hole 30 ball 40 cage 42 outer spherical surface 44 inner spherical surface 46 pocket α taper angle

Claims (5)

An outer joint member in which a plurality of ball grooves extending in the axial direction to the opening end are formed at equal intervals in the circumferential direction on the inner spherical surface;
An inner joint member in which a plurality of axially extending ball grooves are formed at equal intervals in the circumferential direction on the outer spherical surface;
A plurality of balls that transmit torque by being interposed between the ball grooves of the outer joint member and the ball grooves of the inner joint member that form a pair;
A cage that is interposed between the inner spherical surface of the outer joint member and the outer spherical surface of the inner joint member, and that has pockets for accommodating balls in the circumferential direction;
The opening end side groove bottom of the ball groove of the outer joint member has a tapered shape linearly expanding toward the opening end,
The ball groove of the inner joint member has a taper shape in which the diameter of the outer joint member's non-opening end side groove is linearly expanded toward the anti-opening end side,
The outer spherical center and inner spherical center of the cage are offset to the opposite side by an equal distance in the axial direction with respect to the joint center.
A fixed type constant velocity universal joint, wherein the center of curvature of the ball groove of the outer joint member and the center of curvature of the ball groove of the inner joint member are offset from the joint center by a cage offset amount.   2. The fixed type constant velocity universal joint according to claim 1, wherein the upper limit value of the taper angle of the ball groove of the outer joint member and the inner joint member is 12 [deg.].   The offset amount f between the outer spherical center and the inner spherical center of the cage and the length PCR of the line segment connecting the center of curvature of the ball groove of the outer joint member or the center of curvature of the ball groove of the inner joint member and the center of the ball. The fixed constant velocity universal joint according to claim 1 or 2, wherein the ratio value f / PCR is more than 0 and not more than 0.12.   The fixed type constant velocity universal joint according to any one of claims 1 to 3, wherein an opening end side of the outer joint member is thick in a longitudinal section of the cage.   5. The fixed type constant velocity universal joint according to claim 1, wherein the finish forming of the ball groove of the outer joint member and the ball groove of the inner joint member is cold forging.

Images