JP2007192323A - Cross-groove constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the weight of the inner ring of a cross-groove constant velocity universal joint. <P>SOLUTION: This cross-groove constant velocity universal joint comprises an outer ring 10 having ball grooves 14 in the inner peripheral surface 12, an inner ring 120 having ball grooves 124a, 124b in the outer peripheral surface 122, balls 30 incorporated between the ball grooves 14a, 14b in the outer ring 10 and the ball grooves 124a, 124b in the inner ring 120 formed in pairs, and a cage 40 holding all balls 30 in a same plane. In the inner ring 120, the ball grooves 124a, 124b are formed in a hollow pipe shaft. <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 °.
ER Wagner, “Universal Joint and Driveshaft Design Manual”, SAE, 1991, p.163-166

  In a cross groove type constant velocity universal joint having more than six balls, it is necessary to reduce the diameter of the balls in order to secure the same sliding range as that having six balls. If both joints have the same torque load capacity, the ball diameter of the inner ring becomes shallower as the number of balls increases because the ball diameter is smaller. For this reason, the thickness of the inner ring from the bottom of the ball groove to the radial direction increases, which causes an increase in weight.

  Further, since the inner ring and the shaft are usually fitted with splines (or serrations, the same applies hereinafter), there is a circumferential backlash at the fitting portion, which is a cause of a reduction in vehicle rigidity in the case of a vehicle. It has become.

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

  The cross groove type constant velocity universal joint of the present invention is assembled between an inner ring having a ball groove on the outer peripheral surface, an outer ring having a ball groove on the inner peripheral surface, and a ball groove of the inner ring and a ball groove of the outer ring which make a pair. And a cage for holding all the balls in the same plane, wherein the inner ring is formed by forming a ball groove on a hollow pipe shaft. Since the ball groove is directly formed on the pipe shaft, the inner and outer diameter pipes that have a sufficient thickness in the radial direction from the bottom of the ball groove are used, so that there is no extra wall and a lighter inner ring can be obtained. In addition, since the inner ring and the shaft are integrated from the beginning, it is not necessary to fit by a spline or the like, and as a result, circumferential play can be avoided.

  According to a second aspect of the present invention, in the cross groove type constant velocity universal joint according to the first aspect, the crossing angle with respect to the axis of the outer ring ball groove and the inner ring ball groove inclined in opposite directions is 4.5 ° or more and 8.5 °. And the number of balls is eight. By making the cross angle of the ball groove with respect to the axis of the cross groove type constant velocity universal joint to be 4.5 ° or more and less than 8.5 ° and the number of balls to be 8, the maximum operating angle of the joint is not reduced, The sliding stroke can be earned. As already mentioned, in a cross-groove type constant velocity universal joint, there is a ball in a certain phase, and 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. The drive becomes unstable. As the angle formed by the inner ring ball groove and the outer ring ball groove becomes smaller, this phenomenon becomes prominent when the number of balls is up to six. However, by increasing the number of balls to 8 or more, even if the angle formed by the ball groove of the inner ring and the ball groove of the outer ring becomes small, the driving of the cage is stabilized up to a certain value. This is because the driving force of the ball whose wedge angle is reversed is shared by other balls to stabilize the driving of the cage.

  According to a third aspect of the present invention, in the cross groove type constant velocity universal joint of the first aspect, the crossing angle with respect to the axis of the outer ring ball groove and the inner ring ball groove inclined in opposite directions is 10 ° to 15 °, The number is 10 and can be used for a drive shaft of a vehicle.

  In the cross groove type constant velocity universal joint used for the drive shaft, the crossing angle of the ball groove with respect to the axis is not less than 10 ° and not more than 15 °, and the number of balls is 10, so that the maximum operating angle of the joint is not reduced, Moreover, a sliding stroke can be earned. As already mentioned, in a cross groove type constant velocity universal joint, there is a torque transmission ball at a certain phase, and 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. The cage becomes unstable. When the angle formed by the ball groove of the inner ring and the ball groove of the outer ring becomes smaller, this phenomenon appears remarkably when the number of balls is up to six. However, when the number of balls is ten, even if the angle formed by the ball groove of the inner ring and the ball groove of the outer ring becomes small, the driving of the cage is stabilized up to a certain value. This is because the driving force of the ball whose wedge angle has been reversed is shared by other balls to stabilize the driving of the cage.

  In the cross groove type constant velocity universal joint used for the drive shaft, the required operating angle is about 20 °. As a result of analyzing the operating angle up to 25 °, the crossing angle of the ball groove with respect to the axis is 10 °. If it was above, it was confirmed that a ball | bowl is excellent in a bending characteristic rather than the thing of the conventional type of six pieces.

  In this way, even if the crossing angle of the ball groove with respect to the axis is reduced to increase the sliding stroke, the maximum operating angle is not reduced, and excellent bending characteristics with little catching during bending can be obtained. Therefore, the assemblability at the time of vehicle assembly can be improved. When the crossing angle to the axis is the same between the inner and outer rings, both the constant velocity and bending characteristics can be improved.

  In the cross groove type constant velocity universal joint, even when the number of balls is eight, the bending torque characteristic is superior to the conventional six joints. However, if there are eight, the inclination directions with respect to the axis of the pair of diametrically opposed ball grooves provided on the outer ring or the inner ring are opposite to each other, so that the pair of ball grooves cannot be processed simultaneously, Processability is poor, resulting in decreased productivity and increased cost. On the other hand, when the number of balls is ten, the inclination direction with respect to the axis of the pair of ball grooves facing the diametrical direction provided on the outer ring or the inner ring is 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.

  According to a fourth aspect of the present invention, in the cross groove constant velocity universal joint according to the first aspect, the crossing angle with respect to the axis of the ball groove of the outer ring and the ball groove of the inner ring inclined in opposite directions is 5 ° to 9 °. The number is 10 and can be used for a propeller shaft of a vehicle.

  In the cross groove type constant velocity universal joint used for the propeller shaft, the intersection angle of the ball groove with respect to the axis is set to 5 ° to 9 ° and the number of balls is set to 10, so that the maximum operating angle of the joint is not reduced, Moreover, a sliding stroke can be earned. As already mentioned, in a cross groove type constant velocity universal joint, there is a torque transmission ball at a certain phase, and 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. The cage becomes unstable. When the angle formed by the ball groove of the inner ring and the ball groove of the outer ring becomes smaller, this phenomenon appears remarkably when the number of balls is up to six. However, when the number of balls is ten, the driving of the cage is stable up to a certain value even if the crossing angle formed by the ball groove of the inner ring and the ball groove of the outer ring becomes small. This is because the driving force of the ball whose wedge angle has been reversed is shared by other balls to stabilize the driving of the cage.

  In the cross groove type constant velocity universal joint used for the propeller shaft, the required operating angle is about 10 °. As a result of analyzing the operating angle up to 15 °, the crossing angle of the ball groove is 5 ° or more. If so, it was confirmed that the ball had better bending characteristics than the six conventional types.

  In this way, even if the crossing angle of the ball groove with respect to the axis is reduced to increase the sliding stroke, the maximum operating angle is not reduced, and excellent bending characteristics with little catching during bending can be obtained. Therefore, the assemblability at the time of vehicle assembly can be improved. When the crossing angle to the axis is the same between the inner and outer rings, both the constant velocity and bending characteristics can be improved.

  In the cross groove type constant velocity universal joint, even when the number of balls is eight, the bending torque characteristic is superior to the conventional six joints. However, if there are eight, the inclination directions with respect to the axis of the pair of diametrically opposed ball grooves provided on the outer ring or the inner ring are opposite to each other, so that the pair of ball grooves cannot be processed simultaneously, Processability is poor, resulting in decreased productivity and increased cost. On the other hand, when the number of balls is ten, the inclination direction with respect to the axis of the pair of ball grooves facing the diametrical direction provided on the outer ring or the inner ring is 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.

  According to the present invention, only the necessary thickness in the radial direction can be ensured from the ball groove bottom of the inner ring, and the excess thickness can be reduced. Therefore, the weight reduction of the inner ring and consequently the cross groove type constant velocity universal joint can be achieved.

  Further, since the ball groove is provided in the pipe shaft, it is not necessary to fit the inner ring and the shaft by a spline or the like as in the prior art, and the play generated in the fitting portion is also free.

  The present invention can be applied regardless of the number of balls. For example, the present invention applies to a cross-groove type constant velocity universal joint using more than six balls, which is generally used in the past. be able to. However, the larger the number of balls, the smaller the ball diameter in terms of ball arrangement, and the thicker the inner ring ball groove bottom becomes. Therefore, the effect of the present invention becomes more prominent as the number of balls increases.

  According to the second aspect of the present invention, even if the crossing angle of the ball groove with respect to the axis is made small in order to increase the sliding stroke of the cross groove type constant velocity universal joint, no catching occurs at the time of bending. It will not get smaller. Therefore, it is possible to increase the sliding stroke without reducing the maximum operating angle of the cross groove type constant velocity universal joint.

  According to the invention of claim 3, since the intersection angle of the ball groove with respect to the axis is 10 ° or more and 15 ° or less and the number of balls is set to 10, the intersection angle of the ball groove with respect to the axis is reduced to increase the sliding stroke. But the maximum operating angle is not reduced. Therefore, excellent bending characteristics with little catching at the time of bending can be obtained, and the assemblability at the time of vehicle assembly can be improved. Further, when the crossing angle with respect to the axis is the same between the inner and outer rings, both the constant velocity property and the bending property can be improved.

  According to the invention of claim 4, since the intersection angle of the ball groove with respect to the axis is not less than 5 ° and not more than 9 ° and the number of balls is 10, the intersection angle of the ball groove with respect to the axis is reduced to increase the sliding stroke. But the maximum operating angle is not reduced. Therefore, excellent bending characteristics with little catching at the time of bending can be obtained, and the assemblability at the time of vehicle assembly can be improved. Moreover, when the crossing angle with respect to the axis is the same between the inner and outer rings, both the constant speed property and the bending property can be improved.

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

  First, the basic configuration of a cross-groove type constant velocity universal joint will be described with reference to FIGS. As shown in FIGS. 3 and 4, 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 here, and ball grooves 14 a and 14 b are formed on the inner peripheral surface 12. Bolt holes 16 are equally arranged in the circumferential direction so as to be positioned between the ball grooves 14 a and 14 b of the outer ring 10. An end cap 52 is attached to one end of the outer ring 10, and a boot adapter 54 is attached to the other end. In addition to the disk type illustrated here, the outer ring includes a flange type and a bell type.

  An inner ring 20 as an inner joint member has ball grooves 24 a and 24 b formed on an outer peripheral surface 22. As shown in FIG. 3, in a conventional cross groove type constant velocity universal joint, the inner ring 20 has a spline hole and is generally fitted to a spline shaft of a shaft indicated by a broken line so that torque can be transmitted.

  As shown in FIG. 5, the ball grooves 14a inclined with respect to the axis of the outer ring 10 and the ball grooves 14b inclined in the direction opposite to the ball groove 14a 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. 6, 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 and 14b; 24a and 24b is schematically shown in FIG. 7, the ratio (D / d) of the ball diameter d to the groove diameter D is called a contact rate.

  Although the number of balls 30 is 6 in FIG. 4, FIG. 8 illustrates the case where the number of balls is 10, and FIG. 9 shows a single inner ring in that case. In FIG. 9, the symbol t represents the thickness of the bottom portion of the ball groove of the inner ring.

  Next, an embodiment of the present invention will be described. Except for the matters described below with reference to FIGS. 1 and 2, the basic configuration of the cross groove type constant velocity universal joint described above with reference to FIGS. 3 to 9 is also applied to the embodiment of the present invention. Applicable. FIG. 1A shows an end face of the inner ring 120 in an embodiment applied to a cross groove type constant velocity universal joint using ten balls. In this case, the inner ring 120 has five ball grooves 124a and 124b. FIG. 1B shows a longitudinal section of the inner ring 120, and FIG. 2 is a perspective view of the inner ring 120.

  As can be understood from FIG. 1B and FIG. 2, the inner ring 120 is integral with the shaft. That is, in the case of the illustrated embodiment, ball grooves 124 a and 124 b are formed on the outer peripheral surface of the small-diameter portion 122 using a hollow pipe shaft in which the small-diameter portion 122, the large-diameter portion 128 and the tapered portion 126 between them are welded. It is. The small diameter portion 122 provided with the ball grooves 124a and 124b corresponds to a conventional inner ring. By using the small-diameter portion 122 with the inner and outer diameters such that the wall thickness t (see FIG. 9) of the groove bottom portions of the ball grooves 124a and 124b becomes the minimum value necessary for strength, the inner ring is reduced in weight, and thus the entire joint. Realization of lighter weight. Here, a case where a hollow pipe shaft shaped like a different diameter pipe joint is used is exemplified, but a single straight hollow pipe shaft can also be adopted.

  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 and outer rings 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. Thus, the ball is always held at the intersection of the ball grooves, and is always maintained within the bisector of the operating angle even when an angular displacement occurs between the inner and outer rings. 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 and outer rings. 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.

  It is conceivable to prevent the wedge angle from being reversed by increasing the crossing angle of the ball grooves of the inner and outer rings. 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 If the inner and outer rings 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 formed by the ball grooves of the inner and outer rings 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 above embodiment. 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; 124a, 124b 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 diametrically opposed ball grooves 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 direction with respect to the axis line of the pair of ball grooves opposed to the diameter direction provided in the outer ring or the inner ring is 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 is reduced.

(A) is an end view of an inner ring of a cross groove type constant velocity universal joint showing an embodiment of the present invention, and (B) is a longitudinal sectional view of the inner ring in FIG. 1 (A). 1 is a perspective view of the inner ring in FIG. Longitudinal sectional view of a cross-groove type constant velocity universal joint showing conventional technology End view of the joint of Fig. 3 with the grease cap removed FIG. 3 is a developed view of the inner ring outer peripheral surface and inner ring outer peripheral surface of the joint of FIG. FIG. 3 is a cross-sectional view of the main part of the ball groove in the joint of FIG. Schematic showing the relationship between the ball groove and the ball in the joint of FIG. End view similar to FIG. 4 showing a cross groove type constant velocity universal joint with 10 balls End view of the inner ring in 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 14a, 14b Ball groove 16 Bolt hole 20, 120 Inner ring (inner joint member)
22 outer peripheral surface 24a, 24b; 124a, 124b Ball groove 122 Small diameter portion 126 Tapered portion 128 Large diameter portion 30 Ball (torque transmission element)
40 cage

Claims (4)

  An inner ring having a ball groove on the outer peripheral surface, an outer ring having a ball groove on the inner peripheral surface, a ball assembled between the ball groove of the pair of inner ring and the ball groove of the outer ring, and all the balls in the same plane A cross-groove type constant velocity universal joint comprising a cage for holding, and wherein the inner ring is formed by forming a ball groove on a hollow pipe shaft.   The cross-groove type constant velocity universal according to claim 1, wherein an angle of intersection between an outer ring ball groove and an inner ring ball groove inclined in opposite directions is not less than 4.5 ° and less than 8.5 °, and the number of balls is 8. Fittings.   The cross-groove type constant velocity universal joint according to claim 1, wherein an angle of intersection with an axis of the ball groove of the outer ring and the ball groove of the inner ring inclined in opposite directions is 10 ° to 15 ° and the number of balls is 10.   2. The cross groove type constant velocity universal joint according to claim 1, wherein an angle of intersection between the outer ring ball groove and the inner ring ball groove inclined in opposite directions is 5 ° to 9 ° and the number of balls is 10.