JP2009287711A - Fixed-type, constant-velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed-type, constant-velocity universal joint in which a ball groove depth can be maintained and whose performance can be improved as compared with conventional products without increasing "the outward axial force against the balls" affecting the joint efficiency. <P>SOLUTION: In the fixed-type constant-velocity universal joint, the center of a guide groove 22 of an outer joint member and the center of a guide groove 25 of an inner joint member are offset to the opposite side with respect to the spherical center of an inner diameter surface 21 and with respect to the spherical surface of the outer diameter surface 24 by the equal distance in the axial direction, respectively. A ratio R1 (F/PCR) of an offset amount to the segment length connecting the center of the guide grooves 22, 25, and the center of the ball 27 is within the range of 0.045 to 0.065. The angle formed by the center of an outside diameter surface 28a of a retainer 28 or the center of an inside diameter surface 28b of the retainer 28 and the center of the ball 27 is represented by αt, and the angle formed by the center of the guide grooves 22, 25 and the center of the ball 27 is represented by αc, and the angle added by these angles is represented by α, the rate As (αt/α) is 0.045 to 0.065. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fixed type constant velocity universal joint, and more particularly to a fixed type that is used in power transmission systems of automobiles and various industrial machines, and that allows only angular displacement between two axes of a driving side and a driven side. It relates to a universal joint.

  For example, there is a fixed type constant velocity universal joint as a kind of constant velocity universal joint used as means for transmitting rotational force from an engine of an automobile to wheels at a constant speed. This fixed type constant velocity universal joint has a structure in which two shafts on the driving side and the driven side are connected and rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle. Generally, as the above-mentioned fixed type constant velocity universal joint, as described in Patent Document 1, Patent Document 3, and the like, the Barfield type (BJ) and the undercut free type (UJ) are widely known. Yes.

  For example, an undercut-free (UJ) fixed type constant velocity universal joint is an outer joint in which a plurality of guide grooves 2 are formed on the inner diameter surface 1 along the axial direction at equal intervals in the circumferential direction as shown in FIG. An outer ring 3 as a member, and an inner ring 6 as an inner joint member in which a plurality of guide grooves 5 paired with the guide groove 2 of the outer ring 3 are formed on the outer diameter surface 4 along the axial direction at equal intervals in the circumferential direction. A plurality of balls 7 are interposed between the guide groove 2 of the outer ring 3 and the guide groove 5 of the inner ring 6 to transmit torque, and are interposed between the inner diameter surface 1 of the outer ring 3 and the outer diameter surface 4 of the inner ring 6. And a cage 8 for holding the ball 7. A plurality of window portions 9 in which the balls 7 are accommodated are arranged in the cage 8 along the circumferential direction.

  The groove bottom of the guide groove 2 of the outer ring 3 is composed of a straight part 2a on the opening side (a straight part parallel to the axial direction of the outer ring 3) and a circular arc part 2b on the back side. The groove bottom of the guide groove 5 of the inner ring 6 includes an arc portion 5a on the opening side and a straight portion 5a on the back side (a straight portion parallel to the axial direction of the inner ring 6).

  In this case, the center O1 of the guide groove 2 of the outer ring 3 is in the axial direction with respect to the spherical center O3 of the inner diameter surface 1, and the center O2 of the guide groove 5 of the inner ring 6 is in the axial direction with respect to the spherical center O4 of the outer diameter surface 4, respectively. Are offset to the opposite side by an equal distance F.

  Further, as shown in FIG. 5, a fixed constant velocity universal joint of the Barfield type (BJ) is an outer joint in which a plurality of guide grooves 12 are formed on the inner diameter surface 11 along the axial direction at equal intervals in the circumferential direction. An outer ring 13 as a member, and an inner ring 16 as an inner joint member in which a plurality of guide grooves 15 paired with the guide grooves 12 of the outer ring 13 are formed on the outer diameter surface 14 along the axial direction at equal intervals in the circumferential direction. A plurality of balls 17 that are interposed between the guide groove 12 of the outer ring 13 and the guide groove 15 of the inner ring 16 and transmit torque, and are interposed between the inner diameter surface 11 of the outer ring 13 and the outer diameter surface 14 of the inner ring 16. And a cage 18 for holding the ball 17. A plurality of window portions 19 in which the balls 17 are accommodated are arranged in the cage 18 along the circumferential direction.

  In this case, the groove bottoms of the guide groove 12 of the outer ring 13 and the guide groove 15 of the inner ring 16 are each composed only of an arc portion. The center of curvature O2 of the guide groove 15 of the inner ring 16 and the center of curvature O1 of the guide groove 12 of the outer ring 13 are offset from the joint center O by an equal distance k and k in the opposite direction in the axial direction.

  Generally, a fixed type constant velocity universal joint (tire constant velocity universal joint) used for driving a front tire for an automobile is set to have a low operating angle in a straight traveling state (0 to 10 deg.). degree). When the vehicle turns, it takes a large operating angle according to the steering angle. Considering the usage situation of general automobiles, scenes requiring large steering (garage entry, intersections, etc.) are less frequent, and most are used in a straight line state = low operating angle. Therefore, by improving the efficiency (loss due to friction) of the fixed type constant velocity universal joint at a low operating angle, it can be expected to improve the fuel efficiency of the automobile.

  As shown in FIG. 8, the efficiency improvement of the fixed type constant velocity universal joint is achieved by using a small-diameter ball 17 and reducing the track offset amount k ′ (k ′ <k) to achieve high efficiency and compactness. There is a method for realizing a fixed type constant velocity universal joint (Patent Document 1 and Patent Document 2). Thus, by adopting the small-diameter ball / small track offset, the difference in moving distance between the inner ring 16, the ball 17, the outer ring 13, and the ball 17 is reduced, and the sliding speed between the guide groove 12 of the ball 17 and the outer ring 13 is reduced. Decreases and efficiency increases.

  That is, when the constant velocity universal joint shown in FIG. 5 is compared with the one with a small track offset as shown in FIG. 8, in the constant velocity universal joint shown in FIG. 8, the pinching angle of the ball 17 is β, In the constant velocity universal joint shown in FIG. 8, the pinching angle of the ball 7 is β ′ smaller than the pinching angle β. The force pushing the ball 17 in the axial direction decreases from F to F ′, as shown in FIGS. By reducing the force that pushes the ball 17 in the axial direction, the force by which the cage 18 is pressed against the spherical surface of the inner and outer rings by the ball 17, that is, the spherical force is reduced, and the friction loss at the contact portion is reduced, improving the efficiency.

  FIG. 7 shows a case where the constant velocity universal joint shown in FIG. 5 takes an operating angle (40 deg), and FIG. 10 shows a case where the constant velocity universal joint shown in FIG. 8 takes an operating angle (40 deg). Is the locus of the contact point between the outer ring 13 and the ball 17, and the line L2 is the locus of the contact point between the inner ring 16 and the ball 17.

Incidentally, FIG. 5 shows the case where there are six balls 17 and FIG. 8 shows the case where there are eight balls. The lengths of the contact point trajectories in these cases are compared, and the results are shown in Table 3 below. Described.

As can be seen from Table 3, the length of the contact point trajectory is longer for the six balls than for the eight balls.
JP-A-9-317784 JP 2003-4062 A

  If the structure of a small-diameter ball and a small offset is adopted, it is possible to improve the efficiency of the constant velocity universal joint, but there is a limit to the design in consideration of the balance with the strength. That is, the following contradictory features (a) and (b) appear.

(A) Efficiency decreases as the ball diameter and offset (track offset) are reduced. However, if the ball diameter is made too small, the corresponding guide groove becomes shallow, and when a large torque is input, the ball easily rides on the shoulder of the guide groove, and the strength at high angles decreases. (A) If the offset is made extremely small, the pinching angle generated in the ball becomes small, and as a result, the force for controlling the ball is insufficient, resulting in malfunction such as catching during operation.

  As described above, in the conventional fixed type constant velocity universal joint, the ball diameter reduction and the small offset need to be designed while balancing among the three of strength, operability and efficiency, and the design is inferior. .

  By the way, the track offset represents the guide groove center distance from the center of each spherical surface of the outer and inner rings as described above. In Patent Documents 1 and 2, as shown in FIG. 4, this offset is F, and a line connecting the center O 1 of the guide groove 2 of the outer ring 3 or the center O 2 of the guide groove 5 of the inner ring 6 and the center O 5 of the ball 7. When the ratio when the minute length is PCR is R1 (F / PCR), R1 is set in the range of 0.069 to 0.121.

  In Patent Document 1, the core positions of the outer and inner spherical surfaces of the cage (cage) 8 are offset from each other by an equal distance from the joint center (ball center) O in the axial direction. The factor of the offset amount f is R2 (f / PCR), and this range is set to a range of R2 = 0 to 0.052.

  By the way, when the track offset amount is too large, the track groove becomes shallow, the allowable load torque is reduced in a high operating angle region, and the cage pillar is thinned, thereby reducing the strength of the cage. On the other hand, if the track offset amount is too small, the durability is lowered due to an increase in the track load, and further the maximum operating angle is lowered. As described above, the track offset amount is not preferable whether it is excessive or small, and there is an optimum range.

  Since the optimum range of the offset amount varies depending on the size of the joint, it is necessary to obtain it in relation to the basic dimension representing the size of the joint. Therefore, in the above-mentioned patent document, the ratio R1 (= F / PCR) is used and 0.069 ≦ R1 ≦ 0.121 is ensured of allowable load torque, ensured cage strength, reduced track load, and durability. It is said that it is in the optimum range from the standpoint of ensuring safety and securing the maximum operating angle.

  As described above, even those described in Patent Documents 1 and 2 can provide a highly efficient product having durability while ensuring the necessary strength. However, in order to increase the joint load capacity (increase the track groove depth), it is necessary to make the track offset smaller than that described in the patent document. However, when the track offset is reduced in this way, the operability of the joint may be deteriorated for the reason (b).

  In view of the above problems, the present invention can secure a ball groove depth and improve the performance compared to the conventional product without increasing the “force to push the ball in the axial direction” which affects the joint efficiency. A fixed type constant velocity universal joint is provided.

  The fixed type constant velocity universal joint of the present invention includes an outer joint member in which a plurality of guide grooves are formed on an inner diameter surface, an inner joint member in which a plurality of guide grooves are formed on an outer diameter surface, and guidance of the outer joint member. A plurality of balls interposed between the groove and the guide groove of the inner joint member for transmitting torque, and a cage for holding the ball, wherein the center of the guide groove of the outer joint member is relative to the spherical center of the inner diameter surface The fixed joint constant velocity universal joint in which the center of the guide groove of the inner joint member is offset to the opposite side by an equal distance in the axial direction with respect to the spherical center of the outer diameter surface. And R1 which is F / PCR when the length of the line segment connecting the center of the guide groove of the outer joint member or the center of the guide groove of the inner joint member and the center of the ball is PCR is 0.045 ≦ R1 ≦ 0.065 and the outer diameter surface of the cage A line segment connecting the center or the center of the inner diameter surface of the cage and the center of the ball and a line segment connecting the center of the guide groove of the outer joint member or the guide groove of the inner joint member and the center of the ball. The angle is αt, and the angle formed by the line connecting the center of the outer diameter surface of the cage or the center of the inner diameter surface of the cage and the center of the ball and the line connecting the joint center and the center of the ball is αc, As that is αt / α where α is an angle obtained by adding these angles is 0.045 ≦ As ≦ 0.065.

  According to the present invention, the track offset amount is reduced, and the spherical center of the outer diameter surface of the cage (cage) and the spherical center of the inner diameter surface of the cage (cage) are directed toward the guide groove center with respect to the joint center. The guide grooves can be offset appropriately, and the depth of each guide groove can be increased while ensuring the same total offset amount as that of the conventional product. By increasing the depth of each guide groove, the contact angle between the guide groove and the ball (for example, 33 ° to 38 °) can be increased. In addition, by adding a cage offset (cage offset), it is possible to compensate for the effect of operability degradation due to the reduction of R1 (small track offset).

  Even if the groove bottom of each guide groove is an undercut free type having an arc portion and a straight portion, the groove bottom of each guide groove may be a Rzeppa type having only an arc portion.

  It is preferably used for an automobile propeller shaft.

  In the present invention, by increasing the depth of the guide groove, the load capacity of the joint can be increased, and the durability and strength can be improved. In addition, the contact angle between the guide groove and the ball can be increased, the load on the guide groove can be reduced, and this also improves the durability and strength. Furthermore, the difference in moving distance between the inner ring and the ball and the outer ring and the ball is reduced, and the joint efficiency is improved. In addition, by adding a cage offset, it is possible to compensate for the effect of lowering the operability due to the decrease in R1 (small track offset).

  An undercut free type or a zepper type may be used, and various types corresponding to various usage environments can be configured. For this reason, the optimal constant velocity universal joint can be comprised in the propeller shaft of a motor vehicle.

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

  As shown in FIG. 1, the fixed type constant velocity universal joint according to the present invention has an outer ring 23 as an outer joint member in which a plurality of guide grooves 22 are formed along the axial direction on an inner diameter surface 21, and an outer diameter surface 24. A plurality of guide grooves 25 are provided with an inner ring 26 as an inner joint member formed along the axial direction. The guide groove 22 of the outer ring 23 and the guide groove 25 of the inner ring 26 make a pair, and a ball 27 for transmitting torque is interposed between the guide groove 22 of the outer ring 23 and the guide groove 25 of the inner ring 26. A cage (retainer) 28 is interposed between the inner diameter surface 21 of the outer ring 23 and the outer diameter surface 24 of the inner ring 26, and a plurality of window portions (which are arranged at a predetermined pitch along the circumferential direction of the retainer 28 ( A ball 27 is held in a pocket 29.

  The guide groove 22 of the outer ring 23 includes an opening-side straight portion 22a (a straight portion parallel to the outer ring axis) and a back-side arc portion 22b. The guide groove 25 of the inner ring 26 includes an opening-side arc portion 25a and a back-side straight portion 25b (a straight portion parallel to the outer ring axis). For this reason, this fixed type constant velocity universal joint is an undercut free type.

  As shown in FIG. 2, the center of curvature O <b> 1 of the guide groove 22 of the outer ring 23 is shifted from the joint center O in the axial direction toward the opening side of the outer ring 23. Further, the center of curvature O2 of the guide groove 25 of the inner ring 26 is provided at an equal distance from the joint center O in the axial direction on the far side opposite to the center of curvature O1 of the guide groove 22 of the outer ring 23.

  The spherical surface center O3 of the outer diameter surface 28a of the cage 28 is slightly shifted from the joint center O in the axial direction to the opening side. Further, the spherical center O4 of the inner diameter surface 28b of the cage 28 is provided at an equal distance f away from the joint center O in the axial direction on the far side opposite to the spherical center O3 of the outer diameter surface 28a. That is, the offset amount f of the spherical center O3 is fo, the offset amount f of the spherical center O4 is fi, and fo = fi. Further, the offset amount F (dimension between the curvature center O1 and the spherical center O3) of the curvature center O1 is defined as Fo, and the offset amount F (dimension between the curvature center O2 and the spherical center O4) of the curvature center O2 is Fi. And Fo = Fi.

  The guide groove 22 of the outer ring 23 and the guide groove 25 of the inner ring 26 have a Gothic arch shape formed only by forging or by shaving after forging. As shown in FIG. 3, the guide grooves 22, 25 and the ball 27 are in an angular contact by using a Gothic arch shape. That is, the ball 27 is in contact with the guide groove 22 of the outer ring 23 at two points C11 and C12, and is in contact with the guide groove 25 of the inner ring 26 at two points C21 and C22. The angle formed by the contact points C11, C12, C21, C22 between the center O5 of the ball 27 and the guide grooves 22, 25 with respect to a line segment passing through the center O5 of the ball 27 and the joint center O (see FIG. 1 and the like) The angle α1. The contact angles α1 of the contact points C11, C12, C21, C22 are all equal and are set to 33 ° to 38 °.

  As shown in FIG. 1, the length of a line segment mo connecting the track offset amount (offset amount) F (Fo) and the center of curvature O1 of the guide groove 22 of the outer ring 23 and the center O5 of the ball 27 is represented by PCR (PCRo). The ratio R1 (Fo / PCRo) is 0.045 to 0.065. The length of the line segment mi connecting the track offset amount (offset amount) F (Fi) and the center of curvature O2 of the guide groove 25 of the inner ring 26 and the center O5 of the ball 27 is the ratio R1 of PCR (PCRi) ( Fi / PCRi) is set to 0.045 to 0.065. That is, PCRo and PCRi are the same.

  A line segment mo connecting the center of curvature O1 of the guide groove 22 of the outer ring 23 and the center O5 of the ball 27 and a line segment no connecting the spherical center O3 of the outer diameter surface 28a of the cage 28 and the center O5 of the ball 27. Is a line segment connecting the spherical center O3 of the outer diameter surface 28a of the cage 28 and the center O5 of the ball 27, and a line L connecting the joint axis O and the center O5 of the ball 27. As (αt / α) is 0.045 to 0.065, where αc is the angle formed by and α is the sum of these angles. A line segment mi connecting the center of curvature O2 of the guide groove 25 of the inner ring 26 and the center O5 of the ball 27 and a line segment ni connecting the spherical surface center O4 of the inner surface 28b of the cage 28 and the center O5 of the ball 27 are formed. The angle formed by a line segment ni connecting the spherical center O4 of the inner diameter surface 28b of the cage 28 and the center O5 of the ball 27 and a line L connecting the joint axis O and the center O5 of the ball 27, where αt is the angle. As (αt / α) is set to 0.045 to 0.065, where αc is the sum of these angles and α is α.

  In the patent document, that is, the one shown in FIG. 4, F / PCR is 0.069 to 0.121. Further, f / PCR is 0 to 0.052, and As (αt / α) is 0.66 to 1.00.

  According to the present invention, the track offset amount is reduced, and the spherical center O3 of the outer diameter surface 28a of the cage (cage) 28 and the spherical center O4 of the inner diameter surface 28b of the cage (cage) 28 are set to the joint center O. Thus, the guide grooves 22 and 25 can be appropriately offset toward the guide groove centers O1 and O2, and the depth of the guide grooves 22 and 25 can be increased while ensuring the same total offset amount as that of the conventional product. Thus, by increasing the depth of each guide groove 22, 25, the contact angle (for example, 33 ° to 38 °) α1 between the guide groove 22, 25 and the ball 27 can be increased. Thereby, the load capacity of the joint can be increased, and the durability and strength can be improved. In addition, the contact angle between the guide grooves 22 and 25 and the ball 27 can be increased, the load on the guide grooves 22 and 25 can be reduced, and the durability and strength can be improved. In addition, by adding a cage offset (cage offset), it is possible to compensate for the effect of operability degradation due to the reduction of R1 (small track offset). Furthermore, the difference in moving distance between the inner ring 26 and the ball 27 and the outer ring 23 and the ball 27 is reduced, and the joint efficiency is improved. In addition, by adding a cage offset, it is possible to compensate for the effect of lowering the operability due to the decrease in R1 (small track offset).

  Since the guide groove 22 of the outer ring 23 and the guide groove of the inner ring 26 can be formed only by forging, or by shaving after forging, etc., the guide groove formation of the inner ring 26 and outer ring 23 is a special formation. It can be done easily without any method.

  Moreover, although the said embodiment was a constant velocity universal joint of an undercut free type, as another embodiment, the constant velocity universal joint of the Barfield type (Zepper type) where the groove bottom of a track groove consists only of a circular arc part It may be.

  As described above, the constant velocity universal joint of the present invention can be configured in various types corresponding to various usage environments. For this reason, the optimal constant velocity universal joint can be comprised in the propeller shaft of a motor vehicle. In particular, a constant velocity universal joint including eight or more torque transmission balls can achieve further compactness and weight reduction while ensuring strength, load capacity, and durability.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, as a constant velocity universal joint, the joint operating angle is increased. In addition, as in the embodiment, even if the guide groove bottom is an undercut free type having an arc portion and a straight portion, the undercut free type linear portion has a tapered shape. Also good. Moreover, even if the guide groove bottom has a plurality of arc portions with different curvature radii, the center of curvature of the guide groove of the outer ring and the center of curvature of the guide groove of the inner ring are offset in the radial direction from the joint axis, respectively. (Radial offset) may be used. Furthermore, the circumferential arrangement pitch of the guide grooves may be equal or unequal, and the number of balls may be increased or decreased arbitrarily.

As shown in the following Table 1, F / PCR is 0.069 to 0.121, As (αt / α) is 0.66 to 1.00, and F / PCR is 0.00. Performance evaluation with the product of the present invention in the range of 045 to 0.065 and αt / α of 0.045 to 0.065 was performed.

Table 2 shows the results. In Table 2, the degree of improvement relative to the conventional product is quantified, and the larger the value, the better the improvement compared to the conventional product.

It is sectional drawing of the fixed type constant velocity universal joint which shows 1st Embodiment of this invention. It is sectional drawing of the said fixed type constant velocity universal joint. It is an expanded sectional view which shows the relationship between the ball | bowl of the said fixed type constant velocity universal joint, and a guide groove. It is sectional drawing of the conventional fixed type constant velocity universal joint. It is sectional drawing of the other conventional fixed type constant velocity universal joint. It is a figure which shows the pressing force which acts on the ball | bowl of the fixed type constant velocity universal joint of the said FIG. FIG. 6 is a cross-sectional view of the fixed type constant velocity universal joint of FIG. 5 taken at an operating angle. It is sectional drawing of another conventional fixed type constant velocity universal joint. It is a figure which shows the pressing force which acts on the ball | bowl of the fixed type constant velocity universal joint of the said FIG. FIG. 9 is a cross-sectional view of the fixed type constant velocity universal joint of FIG. 8 taken at an operating angle.

Explanation of symbols

21 inner diameter surface 22 guide groove 22a straight portion 22b arc portion 24 outer diameter surface 25 guide groove 25a arc portion 25b straight portion 27 ball 28 cage 28a outer diameter surface 28b inner diameter surface

Claims (5)

An outer joint member having a plurality of guide grooves formed on the inner diameter surface, an inner joint member having a plurality of guide grooves formed on the outer diameter surface, and the guide groove of the outer joint member and the guide groove of the inner joint member. A plurality of balls that transmit torque by being interposed therebetween, and a cage that holds the balls, and the center of the guide groove of the inner joint member is centered on the spherical surface of the inner diameter surface of the guide groove of the outer joint member. Track offset type fixed constant velocity universal joints that are offset to the opposite side by an equal distance in the axial direction with respect to the spherical center of the outer diameter surface,
R1 which is F / PCR when the track offset amount is F and the length of the line segment connecting the center of the guide groove of the outer joint member or the center of the guide groove of the inner joint member and the center of the ball is PCR. , 0.045 ≦ R1 ≦ 0.065, and the line segment connecting the center of the outer diameter surface of the cage or the center of the inner diameter surface of the cage and the center of the ball, and the guide groove of the outer joint member The angle formed by the line connecting the center or the center of the guide groove of the inner joint member and the center of the ball is αt, and the center of the outer diameter surface of the cage or the center of the inner diameter surface of the cage and the center of the ball The angle formed by the connecting line segment and the line connecting the joint center and the center of the ball is αc, and As is αt / α where α is the sum of these angles, 0.045 ≦ As ≦ A fixed type constant velocity universal joint characterized by being 0.065.   2. The fixed type constant velocity universal joint according to claim 1, wherein a contact angle between each guide groove and the ball is 33 [deg.] To 38 [deg.].   The fixed type constant velocity universal joint according to claim 1 or 2, wherein the groove bottom of each guide groove is an undercut free type having an arc portion and a straight portion.   The fixed type constant velocity universal joint according to claim 1 or 2, wherein a groove bottom of each guide groove is a Rzeppa type consisting of only an arc portion.   It uses for the propeller shaft of a motor vehicle, The fixed type constant velocity universal joint of any one of Claims 1-4 characterized by the above-mentioned.

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