JP2007247848A - Cross groove type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cross groove type constant velocity universal joint with an outer ring having reduced weight. <P>SOLUTION: The cross groove type constant velocity universal joint comprises an inner ring 20 having ball grooves in the outer peripheral face, a disc outer ring 10 having ball grooves 14 in the inner peripheral face, balls 30 incorporated between the ball groove 24 of the inner ring 20 and the ball groove 14 of the outer ring 10 paired therewith, and a cage 40 for holding all balls in the same plane. Bolt holes 16 are arranged between the adjacent ball grooves 14 of the outer ring 10. Between at least the adjacent bolt holes 16, small diameter portions 18 are formed by reducing the outer diameters of portions excluding the axial single ends. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a cross groove type constant velocity universal joint used for a power transmission device in automobiles, railway vehicles, various industrial machines and the like.

  In the cross groove type constant velocity universal joint, the ball groove of the outer ring and the ball groove of the inner ring that make a pair are inclined in opposite directions with respect to the axis, and the adjacent ball grooves are inclined in opposite directions. A ball is incorporated as a torque transmitting element at the intersection of the ball grooves (Non-Patent Document 1). Because of such a structure, rattling between the ball and the ball groove can be reduced, and in particular, it is often used for drive shafts and propeller shafts of automobiles that do not like rattling.

  Non-Patent Document 1 describes the most basic cross groove type constant velocity universal joint. There, the number of balls is 4 or more, generally 6 and the ball groove crossing angle with respect to the axis is such that the ball grooves facing the outer ring and the inner ring do not become parallel when the joint is at the maximum operating angle. The angle is designed to be a wide angle, and is generally described as 13 to 19 °.

In Patent Document 1, in order to avoid a decrease in the maximum operating angle when the inclination of the ball groove with respect to the axis is reduced, the ball groove is not only inclined with respect to the axis but also in a plane including the axis. It has been proposed.
JP-A-5-231435 ER Wagner, “Universal Joint and Driveshaft Design Manual”, SAE, 1991, p.163-166

  The cross-groove type constant velocity universal joint is well known as a disk type depending on the vehicle mounting type (see FIGS. 4 and 5). The disk-type cross groove type constant velocity universal joint uses bolt fastening, and the outer ring has bolt holes equally spaced in the circumferential direction. This bolt hole is arranged between adjacent ball grooves without increasing the outer diameter of the outer ring and in balance with the ball groove position. For this reason, the thickness in the radial direction from the ball groove toward the outer diameter is increased, which causes an increase in weight (see FIG. 9).

  The main object of the present invention is to reduce the weight of the outer ring of the cross groove type constant velocity universal joint.

  The cross groove type constant velocity universal joint of the present invention includes an inner ring having a ball groove on the outer peripheral surface, a disk type outer ring having a ball groove on the inner peripheral surface, and a ball groove of a pair of inner ring and a ball groove of the outer ring. And a cage for holding all the balls in the same plane. Bolt holes are arranged between the adjacent ball grooves of the outer ring, and at least between the adjacent bolt holes and in the axial direction. This is characterized in that the outer diameter of the portion excluding the one end portion is reduced.

  The range of reducing the outer diameter of the outer ring as seen in the cross section may exclude the bolt hole portion as in the invention of the second aspect, or cover the entire circumference including the bolt hole portion as in the third aspect of the invention. The outer diameter may be reduced.

  The range of reducing the outer diameter of the outer ring as viewed in the longitudinal section is the portion excluding one end portion on the end cap side as in the invention of claim 4 or the one end portion on the boot side as in the invention of claim 5. Excluded part.

  The present invention can be applied regardless of the number of balls. For example, in addition to the conventional six balls, a cross-groove type constant velocity universal joint using more than six balls is also used. Can be applied.

  According to the present invention, the radial dimension from the ball groove to the outer diameter, that is, the thickness, is reduced at least between the adjacent bolt holes and excluding one end portion in the axial direction, and the outer ring weight is reduced. Therefore, according to the present invention, it is possible to reduce the weight of the outer ring, and thus the entire cross groove type constant velocity universal joint.

  First, a basic configuration of a cross groove type constant velocity universal joint will be described with reference to FIGS. As shown in FIGS. 4 and 5, the cross groove type constant velocity universal joint includes an outer ring 10, an inner ring 20, a ball 30, and a cage 40 as main components. The outer ring 10 as an outer joint member is a disk type, and ball grooves 14 a and 14 b are formed on the inner peripheral surface 12. Similarly, the inner ring 20 as an inner joint member has ball grooves 24 a and 24 b formed on the outer peripheral surface 22.

  As shown in FIG. 6, the ball grooves 14 a inclined with respect to the axis of the outer ring 10 and the ball grooves 14 b inclined in the direction opposite to the ball groove 14 a with respect to the axis of the outer ring 10 are alternately arranged in the circumferential direction. It is arranged in. Similarly, ball grooves 24a inclined with respect to the axis of the inner ring 20 and ball grooves 24b inclined in the direction opposite to the ball grooves 24a with respect to the axis are alternately arranged in the circumferential direction.

  The crossing angle of each ball groove 14a, 14b; 24a, 24b with respect to the axis is represented by the symbol β. The ball groove 14a of the outer ring 10 and the ball groove 24a of the inner ring 20 which are inclined in opposite directions form a pair, and the angle between the two is represented by 2β. Similarly, the ball groove 14b of the outer ring 10 and the ball groove 24b of the inner ring 20 which are inclined in opposite directions form a pair, and the angle between the two is represented by 2β.

  A ball 30 as a torque transmitting element is incorporated at the intersection between the ball groove 14a of the outer ring 10 and the ball groove 24a of the inner ring 20 and at the intersection of the ball groove 14b of the outer ring 10 and the ball groove 24b of the inner ring 20 that form a pair. .

  As shown in FIG. 7, the ball grooves 14a, 14b; 24a, 24b of the outer ring 10 and the inner ring 20 generally have a Gothic arch or elliptical cross-sectional shape, and the ball 30 and the ball grooves 14a, 14b; 24a, 24b. The contact relationship is angular contact. If the contact angle α of the angular contact is exemplified, it is in the range of 30 to 50 °. If the relationship between the ball 30 and the ball grooves 14a, 14b; 24a, 24b is schematically shown in FIG. 8, the ratio (D / d) of the ball diameter d to the groove diameter D is called the contact rate.

  As shown in FIG. 9, in the conventional cross-groove type constant velocity universal joint, the outer ring 10 has a circular outer shape. As can be seen from FIG. 4, the outer peripheral surface of the outer ring 10 is cylindrical, and an end cap 52 for enclosing grease is covered at one end, and a boot adapter 54 constituting a boot at the other end. Is covered. Therefore, as indicated by a symbol t in FIG. 9, the thickness in the radial direction from the ball groove toward the outer diameter is increased, which causes an increase in weight.

  Next, an embodiment of the present invention will be described. FIG. 1 shows an end face of an outer ring in an embodiment applied to a cross groove type constant velocity universal joint using six balls. In this case, the ball grooves 14a and 14b of the outer ring 10A are also six in total. The bolt holes 16 are equally arranged in the circumferential direction so as to be positioned between the adjacent ball grooves 14a and 14b. The outer ring 10A has a small diameter portion 18 formed by reducing the outer diameter of one end portion in the axial direction, that is, the portion excluding the left end portion in FIG. As can be seen from FIG. 1A, here, the small diameter portion 18 exists over the entire circumference of the outer ring 10A. The small diameter portion 18 in this case can be easily formed by turning, for example. The one end portion in the axial direction left without reducing the outer diameter becomes an attachment portion of the end cap or the boot.

  In the embodiment of FIG. 1, the number of ball grooves 14a and 14b of the ball 30 and hence the outer ring 10A is six, but FIG. 2 shows the end face of the outer ring 10A in the embodiment where the number of balls is ten.

  In the embodiment shown in FIG. 3, except for the bolt hole 16 portion of the outer ring 10B, in other words, the small diameter portion 18 is provided only in the portion between the adjacent bolt holes 16. Thus, the small diameter portion 18 does not need to be continuous over the entire circumference, and may be intermittently arranged in the circumferential direction. The small diameter portion 18 in this case can be formed during the forging process or can be formed by milling after forging.

  As apparent from FIGS. 1 to 3, in these embodiments, the outer ring is reduced in weight compared to the conventional outer ring having a cylindrical outer peripheral surface by the amount of the small diameter portion 18 provided on the outer periphery of the outer ring 10 </ b> A, 10 </ b> B. Achieved. From the viewpoint of weight reduction, the shape of the small diameter portion 18 is not particularly limited. For example, the cross-sectional shape is not limited to the angular cross-sectional shape illustrated in FIG.

  By the way, it is said that the cross groove type constant velocity universal joint basically cannot have a large operating angle. This is because there is an angle (limit angle) where the wedge angle formed by the ball grooves of the inner ring and the outer ring is reversed when the joint takes an operating angle. When the operating angle of the joint exceeds the limit angle, the cage cannot maintain the balance of force and becomes unstable, and it is considered that the function as a constant velocity universal joint is lost. This phenomenon has been confirmed for a general ball having six balls, and it is also known that the limit angle is determined by the contact angle and the crossing angle of the ball groove. In Patent Document 1, it is formulated that the limit angle can be increased by tilting the ball groove even in the plane including the axis. However, it becomes a very difficult shape in terms of manufacturing and quality control.

  In the cross groove type constant velocity universal joint, a wedge angle is formed at the intersection between the ball groove of the outer ring and the ball groove of the inner ring, and the ball is pushed to the pocket surface of the cage by the action of the wedge angle. As a result, the ball is always held at the intersection of the ball grooves, and is always maintained in the bisection plane of the operating angle even when an angular displacement occurs between the inner ring and the outer ring. As described above, the cross-groove type constant velocity universal joint is excellent in that it has a constant velocity and less rattling.

  However, the cross-groove type constant velocity universal joint has a smaller operating angle than the constant velocity universal joint that controls the ball by offsetting the center of the arc-shaped ball groove formed in the axial direction on the inner ring and the outer ring. I can't take it big. This is because when the operating angle is increased, the wedge angle is reversed, and the balance of the force acting on the cage from the ball is lost. As a result, the cage becomes unstable because it cannot balance the force.

  Note that it is conceivable to prevent the wedge angle from being reversed by increasing the angle of intersection of the ball grooves of the inner ring and the outer ring. However, the inner ring and the outer ring need to alternately arrange ball grooves inclined in opposite directions with respect to the axis in the circumferential direction, and it is necessary to avoid interference between adjacent ball grooves, and the crossing angle should be increased. Has its limits.

  The angle 2β formed by the ball groove of the inner ring and the outer ring of the cross groove type constant velocity universal joint is also related to the sliding stroke of the joint. To increase the stroke amount, the angle 2β formed by the ball groove is 2β. It is effective to reduce the size.

  However, if the angle formed by the ball groove of the inner ring and the ball groove of the outer ring is made small in order to increase the sliding stroke of the joint, the maximum operating angle of the joint becomes small. The maximum operating angle is an angle at which a maximum torque appears when an operation of bending and returning the joint is performed without rotating. In the worst case, it does not return with an angle, that is, a catching phenomenon occurs. Such catching at the time of bending becomes a problem when the joint is assembled to an automobile.

  When assembling the joint to the automobile, it is necessary to return it after bending it once. For this reason, if the operating angle is small and a catch occurs at the time of bending, the workability of assembling the joint to the automobile is poor.

  Thus, it can be seen that the cross groove type constant velocity universal joint has a small degree of freedom in the maximum operating angle and the sliding amount. Therefore, it is desirable to increase the sliding stroke without reducing the maximum operating angle of the cross groove type constant velocity universal joint. In other words, even if the crossing angle of the ball groove with respect to the axis is reduced and the sliding stroke is increased, the maximum operating angle is not reduced, and excellent folding characteristics with less catching at the time of folding are obtained, improving the assemblability during vehicle assembly When the inner ring and the outer ring have the same crossing angle with respect to the axis, it is required to provide a cross-groove type constant velocity universal joint that has both excellent constant velocity and bending characteristics.

  In order to confirm the maximum operating angle in the case of 8 balls as in the case of 6 balls, the resistance torque at the time of folding back operation when the bending angle is ± 10 ° was obtained by analysis. 14b; it was found that even when the crossing angle β of 24a, 24b was made small, the phenomenon of catching did not appear until the crossing angle β was 4.5 °.

  FIG. 10 shows the torque required for the folding operation in a condition where no catching occurs and a condition in which the catching occurs, in which the horizontal axis represents the bending angle θ and the vertical axis represents the bending torque. As shown by the solid torque diagram, in the case of the catching condition, the torque has an excessive peak at a certain bending angle as compared with the bending torque in the case of the non-scratching condition shown by the broken line. Whether or not it is caught can be determined based on the presence or absence of this peak.

  Table 1 shows how the cross groove type constant velocity universal joint with 6 balls and the cross groove type constant velocity universal joint with 8 balls each change the bending angle β of the ball groove as much as possible. The result of an experiment to see if time catching occurs. The bending angle θ was ± 10 °. Whether or not a cross groove type constant velocity universal joint is established is determined based on the presence or absence of a catching phenomenon. From Table 1, it was confirmed that in the case of eight balls, even if the ball groove crossing angle β was reduced to 4.5 °, there was no catch, that is, a cross groove type constant velocity universal joint was established. In the case of 6 balls, a catch occurred when the crossing angle β was 8.0 °.

  The limit angle was formulated by the crossing angle of the ball groove with respect to the axis. The formula is established regardless of the number of balls. In other words, even if the number of balls increases, the catching phenomenon should appear. However, as shown in Table 1, it was confirmed that the catching phenomenon due to the wedge angle effect constituted by the ball grooves of the inner ring and the outer ring forming a pair did not occur in eight or more balls. This is because by increasing the number of balls, the force acting on the cage from the balls in a certain phase is lost due to the effect that the wedge angle becomes 0, so that other constant velocity universal joints are covered. It is presumed that they are avoiding instability.

  Next, the hooking of the cross groove type constant velocity universal joint during bending will be described based on the analysis result. The catch is a phenomenon in which excessive torque is required when the joint attempts to return at an operating angle. FIG. 10 shows the relationship between the bending angle and the bending torque when there are six balls. The solid and dashed torque curves show the bending torque at different phases. As can be seen from the solid torque curve shown in the figure, when a catch occurs, a torque peak occurs at a certain bending angle.

  The main dimensions of the analysis model will be described. The model with six balls has a ball diameter of 7/8 (22.225 mm), a PCD of 58.0 mm, an intersection angle of 10 °, and a T100 torque of 748.5 Nm. The model with 10 balls has a ball diameter of 19/32 (15.081 mm), a PCD of 74.0 mm, an intersection angle of 5 °, and a T100 torque of 741.3 Nm.

  FIG. 11 shows the relationship between the bending angle and the bending torque in the case of a cross groove type constant velocity universal joint using 10 balls as in the embodiment of FIG. As shown in the figure, when the number of balls is increased to 10, the bending torque at the time of catching is reduced. When the number of balls is 10, compared to the case of 6 balls, the bending torque at the time of catching is about 1/3 with the same clearance setting, and the angle causing the catching is different. In the joint with 6 balls, the maximum catch was observed in 3 phases, whereas in 10 joints, the maximum catch was observed in 5 phases.

  The relationship between the crossing angle and the operating angle will be described. 12 and 13 show the analysis results of the relationship between the operating angle and the bending torque when the number of balls is 10 and the crossing angle is variously changed. FIG. 12 shows the case for the drive shaft and FIG. 13 shows the case for the propeller shaft. is there. In the following, the numerical values corresponding to the propeller shaft are shown in parentheses. These figures also show curves when the number of balls is six and the crossing angle is 16 ° (10 °). The unit of the crossing angle in the figure is degrees.

  According to the figure, in each example where the crossing angle is 10 ° (5 °) or more, the bending torque is kept low even when the operating angle is 25 ° (15 °). In contrast, with a joint with six balls, even when the crossing angle is as large as 16 ° (10 °), the bending torque increases rapidly as the operating angle increases from around 18 ° (12 °). is doing. From this, it can be seen that the bending characteristic of the joint with 10 balls is improved as compared with that with 6 balls if the crossing angle is 10 ° (5 °) or more. More preferably, the crossing angle is 11 ° (6 °) or more.

  In the case of a cross groove type constant velocity universal joint for a drive shaft (propeller shaft), the required operating angle is generally about 20 ° (10 °), so the operating angle is up to 25 ° (15 °). It is sufficient that the bending torque is small when viewed in the range. When the crossing angle is large, it is advantageous in terms of bending characteristics. However, as described above, when the crossing angle becomes large, it becomes impossible to earn a sliding stroke. Considering in a practical range, in the case of a cross groove type constant velocity universal joint for a drive shaft (propeller shaft), when the number of balls is 10, the maximum crossing angle is 15 ° (9 °). Therefore, the crossing angle β is preferably in the range of 10 ° (5 °) or more and 15 ° (9 °) or less.

  FIG. 14 shows a joint with 10 torque transmitting balls and a joint with 6 torque balls when the ball contact ratio is two types of 1.06 and 1.02 (four types in total). The relationship between the contact angle α and the bending torque is shown. The relationship between the contact angle and the bending torque will be described with reference to FIG. When the number of balls is ten, the tendency of the influence of the ball contact rate, that is, the tendency of the influence of the groove shape is the same as when the number of balls is six. In the case of ten joints, the influence of the contact rate is almost eliminated at a contact angle of 40 °. When the number of balls is 10, when the ball contact rate is 1.02, the bending torque is low even if the contact rate is 30 °. Therefore, a contact angle is applicable in the range of 30-50 degrees. However, when the ball contact rate is higher than 1.02, for example, 1.06 or higher, it is preferable to set the contact angle to 40 ° or higher, which is a value at which the ball contact rate does not affect the bending torque.

  FIG. 15 is a cross-groove type constant velocity universal joint with 10 balls, in which the horizontal axis represents the crossing angle and the vertical axis represents the constant velocity, and the change in the constant velocity due to the difference in the crossing angle in the case of various operating angles. It is shown. The constant velocity property will be described with reference to FIG. The constant velocity is represented by (input rotation speed−output rotation speed) / (input rotation speed). In general, the smaller the operating angle and the larger the crossing angle, the more uniform. In the conventional product with six balls, when the crossing angle is 16 ° (10 °) and the operating angle is 20 ° (10 °), which is the performance required for the drive shaft (propeller shaft), etc. The speed is about 0.12 (0.07). On the other hand, in the case of 10 torque transmitting balls, when the crossing angle is 16 ° (10 °), which is the same as the conventional product, 0.012 (0.006) when the operating angle is 20 ° (10 °). It is understood that the constant velocity is superior to the conventional product. When the operating angle is 20 ° (10 °) and the joint has 10 balls, if the crossing angle is 10 ° (5 °), the constant velocity will be about 0.16 (0.18). If the crossing angle is 11 ° (6 °), the constant velocity is about 0.08, which is superior to the conventional product.

  Thus, when the number of balls is 10 and the crossing angle is the same as the conventional product of 6 balls when the operating angle is 20 ° (10 °) required as a joint for a drive shaft (propeller shaft), It is also excellent in isokineticity. Moreover, even if the crossing angle is reduced to 10 ° (6 °), the joint has the same speed as the conventional product. From the viewpoint of constant speed, the joint with 10 balls has a small crossing angle. It is possible to earn operating strokes.

  When the number of balls is ten, the balls become small. Therefore, if the load applied to each ball is the same, the torque transmission balls have the ball grooves 14a, 14b; 24a, 24b as compared to the six joints. The contact pressure at the contact portion with the surface becomes high. However, when the number of balls is 10, the load applied to each ball is reduced by increasing the number of balls, so that a design that eliminates the problem of surface pressure is possible.

  In addition, the cross groove type constant velocity universal joint having ten balls is excellent in productivity. That is, in the cross groove type constant velocity universal joint, even if the number of balls is eight, the bending torque characteristics are superior to the conventional six joints. However, if there are eight, the inclination directions with respect to the axis of the pair of ball grooves corresponding to the diameter direction provided on the outer ring or the inner ring are opposite to each other, so that the pair of ball grooves cannot be processed at the same time. Poor property, resulting in decreased productivity and increased cost. On the other hand, when the number of balls is ten, the inclination directions of the pair of ball grooves corresponding to the diameter direction provided on the outer ring or the inner ring are the same direction. Therefore, the pair of ball grooves can be processed simultaneously, the workability of the ball grooves is good, the productivity is excellent, and the cost can be reduced.

(A) is an end view of an outer ring of a cross groove type constant velocity universal joint showing an embodiment of the present invention, and (b) is an AOB sectional view of FIG. 1 (a). (A) is an end view of the outer ring showing a modification of the outer ring in FIG. 1, and (b) is an AOB cross-sectional view in FIG. 2 (a). (A) is an end view of the outer ring of a cross groove type constant velocity universal joint showing another embodiment, (b) is an AOB sectional view of FIG. 3 (a). Longitudinal sectional view of a cross-groove type constant velocity universal joint showing conventional technology End view of the joint of FIG. 4 with the end cap removed 4 is a developed view of the outer ring inner peripheral surface and the inner ring outer peripheral surface of the joint of FIG. 4 is a cross-sectional view of the main part of the ball groove and ball in the joint of FIG. Schematic showing the relationship between the ball groove and the ball in the joint of FIG. End view of the outer ring of the joint of FIG. Graph showing the relationship between bending angle and bending torque The graph which shows the relationship between the operating angle and bending torque in embodiment Graph showing the relationship between operating angle and bending torque for models with different crossing angles (for drive shafts) Graph showing the relationship between operating angle and bending torque for models with different crossing angles (for propeller shafts) Graph showing the relationship between contact rate and bending torque in models with different numbers of balls and different ball contact rates Graph showing the relationship between crossing angle and constant velocity in models with different working angles

Explanation of symbols

10 Outer ring (outer joint member)
12 Inner peripheral surface 14 Ball groove 16 Bolt hole 18 Small diameter portion 20 Inner ring (inner joint member)
22 outer peripheral surface 24 ball groove 30 ball (torque transmission element)
40 Cage 52 End cap 54 Boot adapter

Claims (6)

  An inner ring having a ball groove on the outer peripheral surface, a disk-type outer ring having a ball groove on the inner peripheral surface, a ball incorporated between the ball groove of the inner ring and the ball groove of the outer ring, and all the balls are in the same plane A cage held inside, and bolt holes are arranged between adjacent ball grooves of the outer ring, and the outer diameter of at least the adjacent bolt holes and excluding one end in the axial direction is reduced. Cross groove type constant velocity universal joint.   The cross groove type constant velocity universal joint according to claim 1, wherein the outer diameter is reduced except for a bolt hole portion when viewed in a cross section.   The cross groove type constant velocity universal joint according to claim 1, wherein the outer diameter is reduced over the entire circumference as viewed in a cross section.   The cross groove type constant velocity universal joint according to any one of claims 1 to 3, wherein the one end portion is on an end cap side.   The cross groove type constant velocity universal joint according to any one of claims 1 to 3, wherein the one end portion is on a boot side.   6. The cross groove type constant velocity universal joint according to claim 1, wherein the number of balls is at least six.

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