JP2009174639A - Fixed type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixed type constant velocity universal joint capable of further improving efficiency at a low angle, without changing a constant velocity universal joint basic structure such as a ball diameter and an offset. <P>SOLUTION: This fixed type constant velocity universal joint has an outside joint member for forming a plurality of track grooves 22 on an inner ball surface 21, an inside joint member for forming a plurality of track grooves 25 on an outer ball surface 24, a plurality of balls 27 interposed between the track grooves 22 of the outside joint member and the track grooves 25 of the inside joint member and transmitting torque, and a cage having a window part 29 storing the balls 27 and interposed between the outside joint member and the inside joint member. In at least one track groove 22 of the outside joint member and the inside joint member, a contact angle of a range for contacting the balls 27 at a low operating angle, is set larger than a contact angle of the other range. <P>COPYRIGHT: (C)2009,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 a power transmission system 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 the rotational torque can be transmitted at a constant speed even if the two shafts have an operating angle. In general, as the above-mentioned fixed type constant velocity universal joint, a Barfield type (BJ) and an undercut free type (UJ) are widely known.

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

  Further, the center of curvature O2 of the track groove 5 of the inner ring 6 and the center of curvature O1 of the track groove 2 of the outer ring 3 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 (a constant velocity universal joint on a tire side) used for driving a front tire of an automobile is set to have a low operating angle in a straight traveling state (0 to 10 degrees). 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 (such as when entering a garage or traveling at an intersection) are less frequent, and most are used in a straight 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, the fuel efficiency of the automobile can be expected.

  As shown in FIG. 10, the efficiency of the fixed type constant velocity universal joint is improved by using a small-diameter ball 7 and reducing the track offset amount k ′ (k ′ <k). 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 the moving distance between the inner ring 6 and the ball 7, the outer ring 3 and the ball 7 is reduced, and the sliding speed between the ball 7 and the outer ring track 2 is reduced. , Improve efficiency.

That is, when the constant velocity universal joint shown in FIG. 7 is compared with the one with a small track offset as shown in FIG. 10, the pinching angle of the ball 7 is β in the constant velocity universal joint shown in FIG. In the constant velocity universal joint shown in FIG. 10, the pinching angle of the ball 7 is β ′ smaller than the pinching angle β. The force pushing the ball 7 in the axial direction decreases from F to F ′, as shown in FIGS. By reducing the force pushing the ball 7 in the axial direction, the force by which the cage 8 is pressed against the spherical surface of the inner and outer rings by the ball 7, that is, the spherical force is reduced, and the friction loss at the contact portion is reduced, thereby improving the efficiency.
FIG. 9 shows the case where the constant velocity universal joint shown in FIG. 7 takes an operating angle (40 deg), and FIG. 12 shows the case where the constant velocity universal joint shown in FIG. 10 takes an operating angle (40 deg). Is the locus of the contact point between the outer ring 3 and the ball 7, and the line L2 is the locus of the contact point between the inner ring 6 and the ball 7.

  7 shows a case where there are six balls, and FIG. 10 shows a case where there are eight balls. The lengths of contact point trajectories in these cases are compared, and the results are shown in Table 1 below. did.

As can be seen from Table 1, it can be seen that the length of the contact point trajectory of the six balls is longer than that of the eight balls.
Japanese Patent No. 3460107 JP-A-9-317784

  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. The smaller the ball diameter and offset, the better the efficiency. However, if the ball diameter is too small, the corresponding track groove becomes shallow, and when a large torque is input, the ball can easily ride on the shoulder of the track groove, and the strength at high angles decreases. 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 order to reduce the ball diameter and the offset in the conventional fixed type constant velocity universal joint, it is necessary to design the balance between strength, operability and efficiency, and the design is inferior.

  In view of the above-mentioned problems, the present invention is a fixed type constant velocity universal that is excellent in design and can further improve the efficiency at low angle without changing the basic structure of the constant velocity universal joint such as the ball diameter and the offset. Provide fittings.

A first fixed type constant velocity universal joint of the present invention includes an outer joint member having a plurality of track grooves formed on an inner spherical surface, an inner joint member having a plurality of track grooves formed on an outer spherical surface, and the outer joint member. A plurality of balls that are interposed between the track grooves of the inner joint member and the track grooves of the inner joint member, and transmit a torque, and have a window portion that accommodates the balls, and are interposed between the outer joint member and the inner joint member. A fixed constant velocity universal joint provided with a cage, wherein at least one track groove of the outer joint member and the inner joint member has a contact angle in a range where the ball contacts at a low operating angle, in another range. This is set to be larger than the contact angle.

  By the way, the heat generated between the balls and the tracks of the inner and outer joint members is caused by sliding friction caused by the difference in track length between the tracks of the inner joint member and the outer joint member. In other words, since the track length of the outer joint member on the outside is longer than the track length of the inner joint member, when the ball sandwiched between the inner and outer tracks rolls, it is longer by the difference in the track length. The ball cannot roll on the side of the outer joint member and slip occurs, resulting in heat generation due to sliding friction. Here, when the contact angle is large, the contact point of the ball with the track of the inner joint member and the track of the outer joint member approaches (the effect is the same as reducing the diameter of the ball), and the inner joint member and the ball / outer joint The difference in the moving distance between the member and the ball is reduced, the amount of sliding friction between the balls and the outer joint member track is reduced, and the efficiency is improved. However, when the contact angle is increased, the ball easily rides on the shoulder of the track groove when the load is large, and the strength is lowered. In particular, in the tracks on the inner side of the inner joint member and the outer joint member used at a high operating angle (the bottom side of the mouse), since the track groove is originally shallow due to the offset, the strength is significantly reduced.

  Accordingly, in the present invention, the contact angle is increased only in the low operating angle region where the track groove depth has a margin, and the conventional contact angle is left in the portion where the track groove depth on the back side has no margin. By adopting this structure, it is possible to improve the efficiency at the low operating angle, which is important for improving the fuel efficiency, while ensuring the strength of the rear truck at the high operating angle. Moreover, such a structure has no design and manufacturing difficulties.

The contact angle in the range where the ball contacts at the low operating angle on the inner joint member side is θ _AI , the contact angle in the range where the ball contacts at the low operating angle on the outer joint member side is θ _AO, and the low contact angle on the inner joint member side The contact angle of the other range outside the range where the ball contacts at the operating angle is θ _BI, and the contact angle of the other range outside the range where the ball contacts at the low operating angle on the outer joint member side is θ _BO . Sometimes θ _AI = θ _AO and θ _BI = θ _BO , θ _AI ≠ θ _AO and θ _BI ≠ θ _BO , and θ _AI > θ _BI and θ _AO > θ _BO .

  The contact range of the ball at the low operating angle and the contact angle of other ranges can be continuously changed along the longitudinal direction of the groove in each range. This allows a smooth movement of the ball.

  The number of the balls can be five or more.

  The bar field type in which the track groove bottom is only an arc portion, the undercut free type having a straight portion at a part of the track groove bottom, or the shape in which the straight portion of the undercut free type is tapered. .

The circumferential arrangement pitch of the track grooves can be unequal.
The center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the axial direction opposite to the joint center, and the offset amount of the track groove of the outer joint member and the inner joint member are offset. The track groove offset amount can be made different.

  In the present invention, it is possible to improve the efficiency at the low operating angle, which is important for improving the fuel efficiency, while ensuring the strength of the rear truck at the high operating angle. That is, it is possible to provide a fixed type constant velocity universal joint that can sufficiently secure joint strength at a high angle while improving the joint efficiency at a low angle without changing the basic structure of the constant velocity universal joint such as a ball diameter and an offset. . Moreover, since such a structure has no design and manufacturing difficulties, such a fixed constant velocity universal joint can be easily manufactured at low cost.

  The track groove bottom has an arc portion and a straight portion, the track groove bottom has a plurality of arc portions with different curvature radii, or the track groove bottom has an arc portion and a taper portion. Or the center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member may be offset in the radial direction from the joint axis, respectively. The number may be 5 or more, and the circumferential pitch of the track grooves may be equal or unequal. 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.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  This fixed type constant velocity universal joint includes an outer ring 23 as an outer joint member in which a plurality of track grooves 22 are formed along the axial direction on an inner spherical surface 21 as shown in FIG. 1, and an outer spherical surface as shown in FIG. 24 includes an inner ring 26 as an inner joint member in which a plurality of track grooves 25 are formed along the axial direction. As shown in FIGS. 3 and 4, the track groove 22 of the outer ring 23 and the track groove 25 of the inner ring 26 make a pair, and the ball 27 for transmitting torque is the track groove 22 of the outer ring 23 and the track groove of the inner ring 26. 25. A cage is interposed between the inner spherical surface 21 of the outer ring 23 and the outer spherical surface 24 of the inner ring 26, and the balls 27 are held in a plurality of windows (pockets) arranged at a predetermined pitch along the circumferential direction of the cage. The

  As shown in FIG. 1, the track groove 22 of the outer ring 23 has its center of curvature O1 shifted from the joint center O in the axial direction toward the opening side of the outer ring 23. Further, as shown in FIG. 2, the center of curvature O2 of the track groove 25 of the inner ring 26 is separated from the joint center O in the axial direction by an equal distance k to the back side opposite to the center of curvature O1 of the track groove 22 of the outer ring 23. Provided.

  As shown in FIGS. 3 and 4, the track groove 22 of the outer ring 23 and the track groove 25 of the inner ring 26 have a radius of curvature R that is larger than the radius r of the ball 27, forging only, or machining after forging. Gothic arch shape molded in In this way, the track grooves 22 and 25 and the ball 27 are in an angular contact by adopting a Gothic arch shape.

The track groove 22 of the outer ring 23 makes a contact angle θ _{AO in} a range A (see FIG. 1) where the ball contacts at a low operating angle different from a contact angle θ _BO in another range B (see FIG. 1). . In this case, larger than the contact angle theta _BO range B contact angle theta _AO range A, that is, the θ _AO> θ _BO. In addition, the track groove 25 of the inner ring 26 makes the contact angle θ _AI in the range A1 (see FIG. 2) where the ball contacts at a low operating angle different from the contact angle θ _{BI in} the other range B1 (see FIG. 2). ing. In this case, the contact angle θ _AI in the range A1 is larger than the contact angle θ _BI in the range B1, that is, θ _AI > θ _BI .

The contact angle refers to the angle between the groove bottom center Q of the ball contact center P and the track grooves 22 and 25 and the ball 27 and the track grooves 22 and 25 are in contact with the center O _B as a reference of the ball 27. The ball contact center P means a point where the major axis and the minor axis of an elliptical contact surface (contact ellipse) formed by contact between the track grooves 22 and 25 and the ball 27 intersect. The long axis refers to the axis that is the longest part in the longitudinal direction of the contact ellipse, and the short axis refers to the axis that is the longest part in the short direction perpendicular to the long axis.

Here, theta _AI = not necessarily a theta _AO and θ _BI = θ _BO, may be a theta _AI ≠ theta _AO and θ _BI ≠ θ _BO. That is, although the contact angle values of the inner and outer rings may be different, the ranges A and A1 in which the ball 27 moves at the low angle of each track of the inner ring 26 and the outer ring 23 are always larger than the other ranges B and B1. Keep it. Here, the low angle time is a low angle time during normal traveling when the constant velocity universal joint is used in an automobile and does not take a large steering when entering a garage or traveling at an intersection.

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

  The contact angles of the range A and the range B of the outer ring 23 do not have to be constant in each case, and may vary smoothly and continuously as shown in FIG. The contact angles of B1 do not need to be constant in each, and may change smoothly and continuously as shown in FIG. This allows a smooth movement of the ball.

  By the way, as a constant velocity universal joint, in order to increase the joint operating angle, even if the track groove bottom is an undercut free type having an arc portion and a straight portion, the undercut free type linear portion is tapered. The thing of the shape which is exhibiting the shape may be sufficient. Also, even if the track groove bottom has a plurality of circular arc portions with different curvature radii, the center of curvature of the outer ring track groove and the center of curvature of the inner ring track groove are offset in the radial direction from the joint axis, respectively. (Radial offset) may be used.

  Furthermore, the offset amount k (axial offset amount) of the track groove 22 of the outer ring 23 and the offset amount k (axial offset amount) of the track groove 25 of the inner ring 26 may be different. In this case, even if the offset amount k of the track groove 22 of the outer ring 23 is larger than the offset amount k of the track groove 25 of the inner ring 26, the offset amount k of the track groove 25 of the inner ring 26 is set to the offset of the track groove 22 of the outer ring 23. It may be larger than the amount k.

  Further, the number of balls may be 5 or more, the circumferential arrangement pitch of the track grooves may be equal pitch or unequal pitch, and the track groove bottom has a plurality of arc portions having different curvature radii. Further, the axial offset amount k of the track groove 22 of the outer ring 23 and the axial offset amount k of the inner ring 26 track groove 22 are different, the center of curvature of the track groove 22 of the outer ring 23 and The center of curvature of the track groove 25 of the inner ring 26 can be offset in the radial direction from the joint axis.

  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 can be made. For example, in the above-described embodiment, the inner ring also in the track groove 22 of the outer ring 23. Also in the track groove 25 of 26, the contact angle θ of the ball movement ranges A and A1 at the low angle is set larger than the contact angle θ of the other ranges B and B1, but such setting is applied to the track of the outer ring 23. It may be performed only on the groove 22 or only on the track groove 25 of the inner ring 26. Such a contact angle may be set in at least one of the track grooves 22 and 25 regardless of whether the contact angle is set on the outer ring side or the inner ring side. That is, the contact angles may be set for all the track grooves 22 and 25 or may be set for any selected number of track grooves 22 and 25.

It is principal part sectional drawing of the outer ring | wheel of the fixed type constant velocity universal joint which shows 1st Embodiment of this invention. It is principal part sectional drawing of the inner ring | wheel of the said fixed type constant velocity universal joint. It is a principal part expanded sectional view of the said fixed type constant velocity universal joint. It is a principal part expanded sectional view of the said fixed type constant velocity universal joint. It is principal part sectional drawing of the outer ring | wheel of the fixed type constant velocity universal joint which shows 2nd Embodiment of this invention. It is principal part sectional drawing of the inner ring | wheel of the fixed type constant velocity universal joint which shows the said 2nd Embodiment. It is sectional drawing of the 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. It is sectional drawing of the state which took the operating angle of the fixed type constant velocity universal joint of the said FIG. 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 FIG. FIG. 12 is a cross-sectional view of the fixed type constant velocity universal joint of FIG. 11 taken at an operating angle.

Explanation of symbols

21 inner spherical surface 22, 25 track groove 24 outer spherical surface 27 ball 28 cage

Claims (10)

An outer joint member having a plurality of track grooves formed on the inner spherical surface, an inner joint member having a plurality of track grooves formed on the outer spherical surface, and between the track grooves of the outer joint member and the track grooves of the inner joint member. A fixed type constant velocity universal joint having a plurality of balls interposed to transmit torque and a cage having a window portion for accommodating the balls and interposed between the outer joint member and the inner joint member. And
In at least one track groove of the outer joint member and the inner joint member, a contact angle in a range where the ball contacts at a low operating angle is set larger than a contact angle in another range, etc. Fast universal joint. The contact angle in the range where the ball contacts at the low operating angle on the inner joint member side is θ _AI , the contact angle in the range where the ball contacts at the low operating angle on the outer joint member side is θ _AO, and the low contact angle on the inner joint member side The contact angle of the other range outside the range where the ball contacts at the operating angle is θ _BI, and the contact angle of the other range outside the range where the ball contacts at the low operating angle on the outer joint member side is θ _BO . The fixed constant velocity universal joint according to claim 1, wherein θ _AI = θ _AO and θ _BI = θ _BO . The contact angle in the range where the ball contacts at the low operating angle on the inner joint member side is θ _AI , the contact angle in the range where the ball contacts at the low operating angle on the outer joint member side is θ _AO, and the low contact angle on the inner joint member side The contact angle of the other range outside the range where the ball contacts at the operating angle is θ _BI, and the contact angle of the other range outside the range where the ball contacts at the low operating angle on the outer joint member side is θ _BO . The fixed constant velocity universal joint according to claim 1, wherein θ _AI ≠ θ _AO and θ _BI ≠ θ _BO and θ _AI > θ _BI and θ _AO > θ _BO are satisfied. The range in which the ball contacts at the low operating angle and the contact angle in other ranges are continuously changed along the longitudinal direction of the groove in each range. Fixed type constant velocity universal joint as described in the item.   The fixed type constant velocity universal joint according to any one of claims 1 to 4, wherein the number of the balls is five or more.   A bar field type in which the track groove bottom has only an arc portion, an undercut free type having a linear portion at a part of the track groove bottom, or a shape in which the linear portion of the undercut free type has a tapered shape. The fixed type constant velocity universal joint of any one of Claims 1-7. 7. The fixed type constant velocity free according to claim 1, wherein the track groove bottoms of the inner joint member and the outer joint member each have a plurality of arc portions having different radii of curvature. Fittings. 8. The center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the radial direction from the joint axis, respectively. Fixed constant velocity universal joint. The fixed constant velocity universal joint according to any one of claims 1 to 8, wherein the circumferential arrangement pitch of the track grooves is an unequal pitch. The center of curvature of the track groove of the outer joint member and the center of curvature of the track groove of the inner joint member are offset in the axial direction opposite to the joint center, and the offset amount of the track groove of the outer joint member and the inner joint member are offset. The fixed constant velocity universal joint according to any one of claims 1 to 9, wherein the offset amount of the track groove is made different.

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