JP2006275099A - Tripod type constant velocity universal joint - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce abrasion of a roller guide surface of an outside joint member in a constant velocity universal joint. <P>SOLUTION: Abrasion of the roller guide surface 14 is reduced by improving a surface property of an outer peripheral surface of a roller 34 for circularly contacting or angularly contacting with the roller guide surface 14 within a range of surface roughness Rk of 0.20 to 0.45 μm by barrel processing. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint used for automobiles and the like, and more particularly to a sliding tripod type constant velocity universal joint.

  In general, a constant velocity universal joint is a type of universal joint that connects two shafts on the drive side and the driven side and can transmit rotational force at a constant speed even if there is an angle between the two shafts. The one that allows relative axial displacement between the two axes by plunging the joint, and the tripod type has a tripod member with three leg shafts protruding in the radial direction as one axis. A hollow cylindrical outer joint member having three track grooves extending in the axial direction is coupled to the other shaft, and the leg shaft of the tripod member is accommodated in the track groove of the outer joint member to transmit torque. It is what I do.

  An example of the sliding tripod type constant velocity universal joint will be described with reference to FIG. 1. Three cylindrical track grooves 2 are formed in the axial direction of the inner peripheral surface of the outer joint member 1, and An annular roller 7 that is rotatably fitted to a cylindrical outer peripheral surface of three leg shafts 5 projecting in the radial direction of a tripod member 4 inserted into the track through a plurality of needle rollers 6 is provided in the track groove 2. It is configured to be inserted into. A pair of roller guide surfaces 3 facing each other in the circumferential direction of each track groove 2 is an arc-shaped concave curved surface parallel to the axial direction, and the outer peripheral surfaces of the rollers 7 of the three leg shafts 5 are adapted to the roller guide surfaces 3. It is an arcuate convex curved surface. Each roller 7 engages with the roller guide surface 3 of the corresponding track groove 2 (circular contact), and can move along the track groove 2 while rotating about the leg shaft 5. Such a sliding tripod type constant velocity universal joint transmits rotational torque between the outer joint member 1 and the tripod member 4 by the engagement of the side surface of the track groove 2 and the roller 7.

  Incidentally, as shown in FIG. 1B, when the rotational force is transmitted with the joint at the operating angle θ, the roller 7 and the roller guide surface 3 are obliquely crossed as shown in FIG. It becomes a relationship. In this case, the roller 7 tries to roll in the direction indicated by the arrow t in FIG. 1B, whereas the track groove 2 is a part of a cylindrical surface parallel to the axis of the outer joint member. 7 moves while being restrained by the track groove 2. As a result, a slip occurs between the roller guide surface 3 and the roller 7 to generate a slide resistance, and this slip generates an induced thrust in the axial direction. Such sliding resistance and induced thrust cause vibrations and noise of the vehicle body.

For example, a double roller type constant velocity universal joint shown in FIG. 2 is known as a sliding tripod type constant velocity universal joint intended to reduce the sliding resistance and induced thrust. In this constant velocity universal joint, the roller 7 of the joint shown in FIG. 1 is a roller cassette made of double inner and outer double rollers, and the roller cassette can be tilted with respect to the leg shaft 22.
Specifically, the constant velocity universal joint includes an outer joint member 10 and a tripod member 20, and the outer joint member 10 has three track grooves 12 extending in the axial direction on the inner peripheral surface. Roller guide surfaces 14 are formed on the side walls of each track groove 12 facing each other in the circumferential direction. The tripod member 20 has three leg shafts 22 projecting in the radial direction, and an outer roller 34 is attached to each leg shaft 22, and the outer roller 34 is accommodated in the track groove 12 of the outer joint member 10. Is done.

 The outer peripheral surface of the outer roller 34 has an arcuate convex cross section having an arc having a center of curvature at a position away from the axis of the leg shaft 22 in the radial direction as a generating line. On the other hand, the cross-sectional shape of the roller guide surface 14 is a Gothic arch shape. As a result, the outer peripheral surface of the outer roller 34 and the roller guide surface 14 form an angular contact at two points (see FIG. 4A). In FIG. 1A, the action lines at the two hit positions are indicated by alternate long and short dash lines. Even if the cross-sectional shape of the roller guide surface 14 is tapered with respect to the outer peripheral surface of the spherical roller, the angular contact between them is realized. By adopting a configuration in which the outer roller 34 and the roller guide surface 14 form an angular contact in this manner, the posture of the roller is stabilized because the roller is less likely to shake. In addition, the angular contact is more advantageous in terms of surface pressure because it has better lubrication intervention than the circular contact and is more than two points per circular contact (see FIG. 4B).

 An angular contact is not employed, and for example, the roller guide surface 14 is configured by a part of a cylindrical surface whose axis is parallel to the axis of the outer joint member 10, and the cross-sectional shape of the circular arc corresponding to the generatrix of the outer peripheral surface of the outer roller 34 There are also types (double roller and circular contact).

 An inner roller 32 is fitted on the outer peripheral surface of the leg shaft 22. The inner roller 32 and the outer roller 34 are unitized via a plurality of needle rollers 36 to form a roller cassette that can rotate relative to each other. As shown in FIG. 1 (B), the needle roller 36 is incorporated in a so-called full roller state in which as many rollers as possible are inserted and no cage is provided. Reference numerals 33 and 35 indicate a pair of washers mounted in an annular groove formed on the inner peripheral surface of the roller 34 to prevent the needle rollers 36 from falling off.

 The outer peripheral surface of the leg shaft 22 has a straight shape parallel to the axis of the leg shaft 22 when viewed in a longitudinal section (FIG. 2A), and the long axis is a joint when viewed in a transverse section (FIG. 2B). The shape of the ellipse is perpendicular to the axis. The cross-sectional shape of the leg shaft is substantially elliptical by reducing the thickness of the tripod member 20 viewed in the axial direction. In other words, in the cross-sectional shape of the leg shaft, the surfaces of the tripod member facing each other in the axial direction are retracted in the mutual direction, that is, on the smaller diameter side than the virtual cylindrical surface.

 The inner peripheral surface of the inner roller 32 has an arcuate convex cross section. In other words, the generatrix of the inner peripheral surface is a convex arc with a radius r (FIG. 2C). Since the cross-sectional shape of the leg shaft 22 is substantially elliptical as described above and a predetermined clearance is provided between the leg shaft 22 and the inner roller 32, the inner roller 32 has a leg shaft. In addition to being able to move in the axial direction of 22, it can swing and swing with respect to the leg shaft 22. Further, as described above, since the inner roller 32 and the roller 34 are unitized so as to be relatively rotatable via the needle rollers 36, the inner roller 32 and the roller 34 can swing as a unit with respect to the leg shaft 22. Is in a relationship. Here, swinging means that the axes of the inner roller 32 and the roller 34 are inclined with respect to the axis of the leg shaft 22 in a plane including the axis of the leg shaft 22.

In the double roller type constant velocity universal joint of FIG. 2, the cross section of the leg shaft 22 is substantially elliptical, and the cross section of the inner peripheral surface of the inner roller 32 is cylindrical. As shown, the contact ellipse of both is close to a point, and the area is also reduced at the same time. Therefore, the force for tilting the roller cassette is greatly reduced compared to the conventional one, and the stability of the posture of the outer roller 34 is further improved. Therefore, the slip resistance during the operating angle operation is reduced, and the occurrence of slide resistance and induced thrust is suppressed.
JP 2000-320563 A

 As shown in FIG. 1 (B), when the constant velocity universal joint transmits the rotational force with the operating angle θ taken, the roller 7 and the roller guide surface 3 are mutually connected as shown in FIG. 1 (C). It becomes a diagonal relationship. Since the track groove 2 is a part of a cylindrical surface parallel to the axis of the outer joint member, the roller 7 moves while being restrained by the track groove 2. As a result, slip occurs between the roller guide surface 3 and the mouth roller 7. The sliding causes wear on the roller guide surface 3, and if this wear proceeds excessively, it causes vibrations and noise in the vehicle body.

  On the other hand, in the double roller type of FIG. 2, since the roller cassette can be tilted with respect to the leg shaft 22 as a whole, the oblique relationship of FIG. 1B does not occur, and the wear of the roller guide surface 3 is relatively small. Instead, slip occurs at the contact portion between the inner peripheral surface of the inner roller 32 and the outer circumferential surface of the joint shaft in the joint circumferential direction, and abrasion similarly occurs at this contact portion. If this wear progresses too much, it will cause vehicle vibration and noise.

 An object of the present invention is to reduce the wear of the roller guide surface by improving the surface properties of the outer peripheral surface of the roller that makes a circular contact or an angular contact with the roller guide surface of the tripod type constant velocity universal joint. Another object of the present invention is to reduce the wear of the contact portion between the inner roller and the leg shaft by improving the surface properties of the inner peripheral surface of the inner roller in the double roller type tripod type constant velocity universal joint.

 In order to solve the above problems, the invention of claim 1 includes an outer joint member in which three track grooves having roller guide surfaces facing in the circumferential direction are formed, and three leg shafts protruding in the radial direction. A constant velocity universal joint that includes a tripod member and a roller that is rotatably fitted to the leg shaft and is inserted into the track groove, the roller being movable in the axial direction of the outer joint member along the roller guide surface The surface of the roller is barrel processed.

 All the surface roughness parameters are reduced by subjecting the outer peripheral surface of the roller used in the sliding tripod type constant velocity universal joint after grinding to barrel processing. The improvement of the surface property of the outer peripheral surface of the roller plays a role of suppressing wear of the outer ring track portion which is a counterpart member.

  The invention of claim 2 is characterized in that, in the invention of claim 1, the surface roughness Rk of the surface of the roller is 0.20 to 0.45 μm. Here, “Rk” is the level difference of the core portion of the roughness curve, and the upper limit level (Rpk: average height of the protruding peak) and the lower limit level (Rvk: protruding valley portion) of the core portion of the roughness curve. The average depth). This “Rk” is a long-term operating surface that affects the wear of the roller guide surface of the outer joint member. “Rpk” is the height of the protruding peak, and is the average height of the protruding peak above the core of the roughness curve. This “Rpk” affects the initial wear. “Rvk” is the depth of the protruding valley, and is the average depth of the protruding valley below the core of the roughness curve. This “Rvk” affects the oil holding capacity.

When 0.45 μm <Rk, the protruding portion (Rpk) of the roughness curve is high, so that the attacking action on the roller guide surface remains and the wear reduction of the roller guide surface is insufficient. When Rk <0.20 μm, the protruding valley portion (Rvk) of the roughness curve is shallow, so that the action as an oil reservoir, that is, the lubricating action becomes insufficient, and similarly the wear reduction of the roller guide surface becomes insufficient.
According to a third aspect of the present invention, in the first or second aspect of the present invention, the outer peripheral surface of the roller is in circular contact with the roller guide surface.

 According to a fourth aspect of the present invention, in the first or second aspect of the invention, the outer peripheral surface of the roller is in angular contact with the roller guide surface at two points.

 The invention according to claim 5 is the constant velocity universal joint according to claim 1, wherein the roller is fitted to the inner roller that is fitted onto the leg shaft, and the outer circumference of the inner roller is fitted via a rolling element. A double-roller type roller cassette having an outer roller inserted in a track groove, wherein the inner peripheral surface of the inner roller is formed in an arcuate convex cross section, and the outer peripheral surface of the leg shaft is straight in the vertical cross section And in the cross section, a gap is formed between the inner peripheral surface of the inner roller in the axial direction of the joint and in contact with the inner peripheral surface of the inner roller in a direction orthogonal to the axis of the joint, In the constant velocity universal joint in which the spherical outer peripheral surface of the outer roller is in angular contact with the roller guide surface at two points, barrel processing is performed on the surfaces of the outer roller and the inner roller, and the surface The surface roughness Rk is characterized in that the 0.20～0.45Myuemu.

 In this way, by barreling the outer peripheral surface of the roller after grinding, the surface roughness parameter of the roller rolling surface is improved, and Rpk and Rk attacking the roller guide surface which is the counterpart member are effectively reduced. On the other hand, the valley portion Rvk that acts as an oil sump can maintain and ensure a lubricating effect because the rate of reduction by the barrel is small.

 According to a sixth aspect of the present invention, there is provided an outer joint member having three track grooves having roller guide surfaces facing in the circumferential direction, a tripod member having three leg shafts projecting in the radial direction, and the leg shaft. In a constant velocity universal joint that includes a roller that is rotatably fitted to the track groove and that is inserted into the track groove, and the roller is movable in the axial direction of the outer joint member along the roller guide surface. The surface roughness Rk is 0.20 to 0.45 μm by barreling after grinding.

  Thus, by performing barrel processing after grinding, the fine groove-like recesses formed on the roller surface by grinding can be reliably left with high distribution density. It can effectively function as an oil reservoir and stably maintain and ensure the lubricating action.

 By applying barrel processing to the surface of the roller used in the sliding tripod type constant velocity universal joint, the roughness parameter of the roller can be improved and the wear of the roller guide surface of the outer joint member which is the counterpart can be reduced. When applied to a drive shaft or propeller shaft of an automobile, phenomena such as vehicle body vibration and noise caused by increased wear can be suppressed. Further, by setting the surface roughness Rk of the roller surface to 0.20 to 0.45 μm by barrel processing, it is possible to reduce the wear of the roller guide surface of the outer joint member that is the counterpart component.

 The contact state between the roller and the roller guide surface of the outer joint member, which is the mating component, is roughly divided into an angular contact and a circular contact. However, the present invention has a relatively large effect with a circular contact type in which the lubrication conditions are more severe. It is done.

 However, even in the angular contact type, an increase in the contact surface pressure is unavoidable when a lighter and more compact structure is promoted. Therefore, wear of the roller guide surface of the outer joint member can be effectively suppressed by the present invention even in the angular contact type.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The constant velocity universal joint of the present invention is the same as the conventional constant velocity universal joint illustrated in FIGS. 1 and 2 except for improving the surface property of the roller. Therefore, the description of FIGS. 1 and 2 is used as it is for the structure of the constant velocity universal joint.

 The present invention barrels the surface of the roller. There are a plurality of types of barrel processing such as rotary barrel processing, vibration barrel processing, centrifugal barrel processing, and gyro processing (spindle processing). Although the present invention employs rotary barrel machining, other types of barrel machining can also be employed.

  The surface roughness (Rk) of the roller surface is desirably in the range of 0.20 to 0.45 μm. When 0.45 μm <Rk, the protruding portion (Rpk) of the roughness curve is high, so that the attacking action on the roller guide surface remains and the wear reduction of the roller guide surface is insufficient. When Rk <0.20 μm, the protruding valley portion (Rvk) of the roughness curve is shallow, so that the action as an oil reservoir, that is, the lubricating action becomes insufficient, and similarly the wear reduction of the roller guide surface becomes insufficient.

 Here, the surface roughness will be described with reference to FIG. In FIG. 3, the left side shows the special roughness curve of the target surface, and the right side shows the load length ratio (Mr%). In the present invention, the special load curve parameter of DIN 4776 is to evaluate the lubricity by dividing the load curve shown in FIG. 3 into an initial wear portion, a substantial contact portion, and an oil sump portion. The initial wear load ratio) is Mr1, the load length ratio 2 (oil sump load factor) is Mr2, the initial wear height is Rpk, the oil sump depth is Rvk, and the effective load roughness is Rk. Defined.

Mr1: Load length ratio 1 (initial wear load ratio)
As shown in FIG. 3, a line having a width of 40% in the direction of the tp value (load length ratio) on the load curve is searched for a position where the difference in height between these ends is minimized, and a straight line passing through the two points. The intersection a of the (minimum slope line or equivalent straight line) and the limit line of tp = 0% is obtained, the intersection of the horizontal line from the intersection a and the load curve is defined as c, and the tp value of this intersection c is Mr1 (%) And This represents the load length ratio after initial wear.

Mr2: Load length factor 2 (oil sump load factor)
As with Mr1, the load curve has a width of 40% in the direction of the tp value, a position where the difference in height between the two ends is minimized, a straight line passing through the two points (minimum slope line) and tp = The intersection point b with the 100% limit line is obtained, the intersection point of the horizontal line from the intersection point b and the load curve is defined as d, and the tp value of the intersection point d is defined as Mr2 (%). This represents the load length ratio after long-term wear.

Rpk: initial wear height The area of a right triangle having the side ac as one side and the other side perpendicular to the one side on the limit line of tp = 0% is the 0% limit line, the side ac, and the load Let Rpk (μm) be the height on the 0% limit line that is equal to the area of the portion surrounded by the curve. This represents the initial wear height.

Rvk: Oil sump depth The area of a right triangle having the side bd as one side and the other side perpendicular to the one side on the limit line of tp = 100% is the 100% limit line, the side bd, and the load. The height on the 100% limit line that is equal to the area of the portion surrounded by the curve is Rvk (μm). This represents the depth of the sump valley.

Rk: Effective load roughness Rk (μm) is the height difference between the intersections c and d determined above. This represents the height at which the surface wears before it becomes unusable after prolonged wear.

 5 and 6 show test data relating to the amount of wear of the roller guide surface of the outer joint member in the on-board durability test of the constant velocity universal joint according to the present invention. This data is based on a so-called bench durability test, and it can be seen that a barrel-processed roller has a low Rpk and Rk, and that the barrel process is effective in reducing wear on the roller guide surface.

 FIGS. 7A and 7B three-dimensionally show the difference in the surface properties of the roller with and without barrel processing at a magnification of 1000 times. In FIG. 7A, the surface roughness Rk of the roller surface is 0.30 μm. Compared with FIG. 7B without barrel processing (surface roughness Rk: 0.65 μm), FIG. 7A with barrel processing effectively removes the convex and concave portions of the surface streak-like grinding processing. Therefore, it can be seen that the surface is visually smooth and the surface properties are improved. In addition, it can be seen that the depth level of the concave portion due to grinding is not easily affected by the barrel processing, and the concave portion that functions as an oil reservoir remains firmly.

1 shows a single roller type sliding tripod type constant velocity universal joint, (A) is a cross-sectional view of the joint, (B) is a longitudinal cross-sectional view of the joint at an operating angle, and (C) is an operating angle. It is a perspective view of the roller of the state which constituted. This is a double roller type sliding tripod type constant velocity universal joint. (A) is a cross-sectional view of the joint, (B) is a cross-sectional view of the leg shaft, and (C) is a vertical cross-sectional view of the inner roller. is there. It is explanatory drawing which shows definitions, such as oil sump depth Rvk and effective load roughness Rk, in the special load curve parameter described in DIN4776. It is sectional drawing which shows the contact state of the roller with respect to a roller guide surface, Comprising: (A) is sectional drawing of an angular contact, (B) is sectional drawing of a circular contact. It is a graph which shows the relationship between the surface roughness (Rpk) of a roller outer peripheral surface, and the wear depth of the roller guide surface of an outer joint member. It is a graph which shows the relationship between the surface roughness (Rk) of a roller outer peripheral surface, and the wear depth of the roller guide surface of an outer joint member. It is a three-dimensional state diagram showing the surface properties of the outer peripheral surface of the roller, (A) is a three-dimensional state diagram barreled after grinding, (B) is a three-dimensional state diagram only grinding.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Outer joint member 2 Track groove 3 Roller guide surface 4 Tripod member 5 Leg shaft 6 Needle roller 7 Roller 10 Outer joint member 12 Track groove 14 Roller guide surface 20 Tripod member 22 Leg shaft 32 Inner rollers 33, 35 Washer 34 Outer roller 36 Needle roller θ Working angle

Claims (6)

 An outer joint member in which three track grooves having roller guide surfaces facing in the circumferential direction are formed, a tripod member having three leg shafts projecting in the radial direction, and the outer periphery of the leg shaft are rotatably fitted. And a roller inserted into the track groove, and the roller surface is barrel-processed in a tripod type constant velocity universal joint that is movable in the axial direction of the outer joint member along the roller guide surface. A characteristic tripod type constant velocity universal joint.  2. The tripod constant velocity universal joint according to claim 1, wherein the surface roughness Rk of the surface of the roller is 0.20 to 0.45 [mu] m.  The tripod type constant velocity universal joint according to claim 1 or 2, wherein the outer peripheral surface of the roller is in circular contact with the roller guide surface.  The tripod type constant velocity universal joint according to claim 1 or 2, wherein the outer peripheral surface of the roller is in angular contact with the roller guide surface at two points.  An outer joint member in which three track grooves having roller guide surfaces facing in the circumferential direction are formed, a tripod member having three leg shafts projecting in the radial direction, and the outer periphery of the leg shaft are rotatably fitted. A tripod type constant velocity universal joint that is movable in the axial direction of the outer joint member along the roller guide surface, and the roller is attached to the leg shaft. A double-roller type roller cassette having an outer-fitted inner roller and an outer roller that is fitted to the outer periphery of the inner roller via a rolling element and inserted into the track groove, and the inner peripheral surface of the inner roller is The outer circumferential surface of the leg shaft is formed into a straight shape in the longitudinal section, and in the transverse section in the direction orthogonal to the axis of the joint. A gap is formed between the inner peripheral surface of the inner roller and the inner peripheral surface of the inner roller in the axial direction of the joint, and the spherical outer peripheral surface of the outer roller is an angular contact at two points with respect to the roller guide surface. In the tripod type constant velocity universal joint, the tripod type etc. characterized in that the surface of the outer roller and the inner roller is subjected to barrel processing, and the surface roughness Rk is 0.20 to 0.45 μm. Fast universal joint.   An outer joint member in which three track grooves having roller guide surfaces facing in the circumferential direction are formed, a tripod member having three leg shafts projecting in the radial direction, and the outer periphery of the leg shaft are rotatably fitted. And a roller inserted into the track groove, wherein the roller is movable in the axial direction of the outer joint member along the roller guide surface. A surface processing method for a roller of a tripod type constant velocity universal joint, characterized in that the surface roughness Rk is 0.20 to 0.45 μm by processing.

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