WO2023068018A1

WO2023068018A1 - Tripod-type constant-velocity universal joint

Info

Publication number: WO2023068018A1
Application number: PCT/JP2022/036825
Authority: WO
Inventors: 卓板垣; 達朗杉山; 将太河田
Original assignee: Ntn株式会社
Priority date: 2021-10-22
Filing date: 2022-09-30
Publication date: 2023-04-27
Also published as: CN219809306U; CN116006589A; JP2023062929A

Abstract

A tripod-type constant-velocity universal joint 1 is provided with: an outside joint member 2 having formed therein three track grooves 5 each having roller guide surfaces 6 disposed so as to face each other in the circumferential direction; a tripod member 3 having three leg shafts 7 protruding in radial directions; and torque transmission members 4, 11 that have rollers 11 rollably fitted in the respective track grooves 5 in the outside joint member 2 and are supported on the leg shafts 7. The tripod-type constant-velocity universal joint is characterized in that: a central range W is defined in a range 10 mm to the depth side and 10 mm to the opening side with respect to a slide range central portion C of each of the track grooves in the joint axial direction; the central range W has formed therein a section 6a where a track length L, which is a width dimension between the roller guide surfaces 6, is minimum; track clearances δ are formed between the roller guide surfaces and the outer circumferential surface of the corresponding roller 11 in the central range W, the minimum value δmin of the track clearances δ of the three track grooves 5 in the central ranges W is set to 0.010-0.100 mm, and the mutual difference in the track lengths L of the three track grooves 5 in the central ranges W is set not more than 0.150 mm.

Description

Tripod type constant velocity universal joint

This invention relates to a tripod type constant velocity universal joint.

A constant velocity universal joint, which constitutes the power transmission system of automobiles and various industrial machines, connects two shafts on the drive side and the driven side so that torque can be transmitted, and transmits rotational torque at a constant speed even if the two shafts change their operating angles. can do. Constant velocity universal joints are broadly classified into fixed type constant velocity universal joints that allow only angular displacement and sliding type constant velocity universal joints that allow both angular displacement and axial displacement. In the drive shaft that transmits power to the driving wheels, a sliding constant velocity universal joint is used on the differential side (inboard side), and a fixed constant velocity universal joint is used on the driving wheel side (outboard side). be.

A tripod type constant velocity universal joint is one of the sliding constant velocity universal joints. In this tripod type constant velocity universal joint, there are known a single roller type roller and a double roller type roller as a torque transmission member. A double-roller type tripod type constant velocity universal joint (hereinafter simply referred to as a tripod type constant velocity universal joint) is mainly composed of an outer joint member, a tripod member as an inner joint member, and a roller unit as a torque transmission member. is configured.

The outer joint member has three linear track grooves extending in the axial direction formed on its inner peripheral surface at equal intervals in the circumferential direction. A roller guide surface is formed extending in the direction. A tripod member and a roller unit are housed inside the outer joint member. The tripod member has three radially projecting legs. The roller unit is mainly composed of a roller, an inner ring placed inside the roller and fitted on the pedestal, and a plurality of needle rollers interposed between the roller and the inner ring. and housed in the track grooves of the outer joint member. The inner peripheral surface of the inner ring forms an arcuate convex surface in a longitudinal section including the axis of the inner ring.

The outer peripheral surface of each leg shaft of the tripod member has a straight shape in a longitudinal section including the axis of the leg shaft, a substantially elliptical shape in a cross section perpendicular to the axis of the leg shaft, and a direction perpendicular to the axis of the joint. It is in contact with the inner peripheral surface of the inner ring, and a gap is formed between it and the inner peripheral surface of the inner ring in the axial direction of the joint. In this tripod type constant velocity universal joint, the rollers of the roller unit attached to the leg shaft of the tripod member roll on the roller guide surfaces of the track grooves of the outer joint member. Since the cross-section of the leg shaft is substantially elliptical, when the tripod-type constant velocity universal joint takes an operating angle, the axis of the tripod member is inclined with respect to the axis of the outer joint member, but the roller unit is aligned with the tripod member. It is tiltable with respect to the axis of the leg shaft. Therefore, since the rollers roll correctly on the roller guide surface, it is possible to reduce the induced thrust and the slide resistance, and it is possible to reduce the vibration of the joint (Patent Document 1). Angular contacts and circular contacts are mainly applied to the shape of the three track grooves having roller guide surfaces formed in the outer joint member.

Patent Document 2 proposes a method of setting the minimum value of the track clearance in a sliding tripod type constant velocity universal joint to a partially negative clearance (tightening allowance) of -50 μm to +10 μm in an unloaded state.

Japanese Patent Application Laid-Open No. 2001-132766 JP 2018-71757 A

In the sliding tripod type constant velocity universal joint, the inside of the cup portion of the outer joint member is finished by cold forging, and after heat treatment, the inside of the cup portion is generally not finished by grinding or the like. Therefore, in addition to the effect of cold forging accuracy, heat treatment deformation caused by heat treatment of the roller guide surfaces of the track grooves causes the track diameter, which is the width dimension between the roller guide surfaces, to vary among the three track grooves. occur. In other words, the difference between the maximum and minimum track diameters increases between the three track grooves. The difference between the maximum and minimum values of the track diameters of the three track grooves is called the mutual difference of the track diameters. The mutual difference between the track diameters affects the dispersion of the track clearance, which is the clearance between the track diameter and the outer diameter of the roller. In other words, it affects the difference between the maximum value and the minimum value of the track clearance between the three track grooves. The difference between the maximum value and the minimum value of the track clearance between the three track grooves is also called the mutual difference of the track clearance.

If the mutual difference between the track clearances becomes excessive, misalignment occurs between the axis of the outer joint member and the axis of the tripod member, and there is a possibility that the load may not be received evenly among the three track grooves when torque is applied. occur. As a result, specific track grooves receive a concentrated load on the roller guide surfaces of the track grooves and on the leg shafts of the rollers and tripod members, which are internal parts. is likely to decline. Details will be described later.

The method of Patent Document 2, in which the minimum value of the track clearance is set to a partial negative clearance (clamping allowance) of -50 μm to +10 μm in a no-load state, has the effect of suppressing the mutual difference in track clearance due to the negative clearance. Considering the ease of handling, such as the large sliding resistance when mounted on a vehicle under load, it was concluded that a correct track clearance is desirable.

In tripod type constant velocity universal joints, it is common to select and combine the roller outer diameter with respect to the track diameter of the outer joint member in order to secure an appropriate track clearance. It is important in terms of productivity and manufacturing cost to make it possible.

In view of the above problems, the present invention enables practical use of a selected combination of rollers for the track diameter of the outer joint member based on the practical accuracy level of forging and heat treatment, and improves durability, strength, and NVH characteristics. It is an object of the present invention to provide a tripod-type constant velocity universal joint capable of ensuring

In order to achieve the above objects, the present inventors have investigated (a) precision at the limit of forging and heat treatment, (b) possibility of efficient practical use of a selected combination of rollers for track diameters, and (c) durability. Various multifaceted items such as securing of durability, strength, and NVH characteristics (vibration characteristics) were examined. As a result, the key to the solution was to focus on the circumferential backlash in the central range of the joint axial direction of the track grooves, which is the slide range most frequently used in actual vehicles equipped with tripod type constant velocity universal joints. The new idea of setting the minimum value of the track clearance and the mutual difference of the track diameters in the middle range led to the present invention.

As a technical means for achieving the above object, the present invention provides an outer joint member formed with three track grooves having roller guide surfaces arranged in circumferentially opposite directions, and a radially projecting roller guide surface. A constant velocity tripod type comprising: a tripod member having three leg shafts; and a torque transmission member having rollers that are rotatably inserted into track grooves of the outer joint member and supported by the leg shafts. In the universal joint, the range from 10 mm on the inner side to 10 mm on the opening side with respect to the center of the slide range of the track groove in the joint axial direction is defined as a center range, and the width dimension between the roller guide surfaces is defined in the center range. A portion having a minimum track diameter is formed, a track clearance is formed between the roller guide surface and the outer peripheral surface of the roller in the central region, and the minimum value of the track clearance of the three track grooves in the central region is 0.010 mm or more and 0.100 mm or less, and the mutual difference in track diameter of the three track grooves in the central area is 0.150 mm or less. With the above configuration, based on the practical accuracy level of forging and heat treatment, it is possible to practically select and combine rollers for the track diameter of the outer joint member, and to ensure durability, strength, and NVH characteristics. Joints can be realized.

As an advantageous configuration, by setting the mutual difference between the track diameters of the three track grooves in the above-mentioned central range to 0.100 mm or less, it is possible to promote the securing of durability, strength, and NVH characteristics (low vibration characteristics). .

An inner ring that rotatably supports the roller is provided, the inner ring is fitted onto the leg shaft, and the roller is movable in the axial direction of the outer joint member along the roller guide surface, thereby induced thrust and slide resistance can be reduced, and low vibration of the joint can be realized.

The inner peripheral surface of the inner ring is arcuately convex in the longitudinal section of the inner ring, and the outer peripheral surface of the leg shaft is straight in the longitudinal section including the axis of the leg shaft. The cross section perpendicular to the axis has a substantially elliptical shape, and the outer peripheral surface of the leg shaft contacts the inner peripheral surface of the inner ring in the direction perpendicular to the axis of the joint, and the inner ring in the axial direction of the joint. A clearance is formed between the roller and the inner peripheral surface, and the roller can be tilted within the track groove. As a result, the tilting motion of the roller in the track groove becomes smooth, and it is possible to reduce the induced thrust and slide resistance and reduce the vibration of the joint.

By arranging a plurality of rolling elements between the inner ring and the roller, the relative rotation between the inner ring and the roller can be smoothed.

Because the rolling elements are needle rollers, the relative rotation between the inner ring and the rollers can be smoothed, and the internal parts can be made compact.

Either angular contact or circular contact can be applied as the form of contact between the roller and the roller guide surface.

According to the present invention, based on the practical accuracy level of forging and heat treatment, it is possible to practically select and combine rollers for the track diameter of the outer joint member, and to ensure durability, strength, and NVH characteristics. Joints can be realized.

According to the present invention, since it is possible to suppress backlash in the circumferential direction and ensure NVH characteristics, it is particularly suitable for tripod-type constant-velocity motor-driven electric vehicles that require improved rotational torque transmission responsiveness and improved quietness. Universal joints can be realized.

1 is a longitudinal sectional view of a tripod type constant velocity universal joint according to a first embodiment of the present invention; FIG. FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1; FIG. 2 is a plan view of the roller unit and the leg shaft as viewed along line BB in FIG. 1; 4 is a longitudinal sectional view of the roller unit taken along line EE of FIG. 3; FIG. FIG. 2 is a vertical cross-sectional view showing a state in which the tripod type constant velocity universal joint of FIG. 1 takes a normal working angle; FIG. 2 is a longitudinal sectional view showing a state in which the tripod-type constant velocity universal joint of FIG. 1 assumes an operating angle larger than the normal operating angle; FIG. 7b is a cross-sectional view taken along the line ZZ in FIG. 7b showing the details of the track grooves of the outer joint member in FIG. 1 in the joint axial direction. FIG. 2 is a vertical cross-sectional view showing details of track grooves of the outer joint member of FIG. 1 in the joint axial direction; Fig. 7b is an enlarged cross-sectional view in the central region W of Figs. 7a, 7b; FIG. 9 is a partial cross-sectional view showing the minimum value of track clearance in FIG. 8; FIG. 9 is a partial cross-sectional view showing the maximum value of the track clearance in FIG. 8; FIG. 5 is a partial cross-sectional view showing the minimum track clearance in the case of circular contacts; FIG. 5 is a schematic diagram for explaining that the load becomes non-uniform for each leg axle due to mutual differences in track clearances; 7b is a cross-sectional view showing a modification of the bottom shape of the cup portion of the track groove of FIG. 7a; FIG. FIG. 5 is a cross-sectional view of a tripod-type constant velocity universal joint according to a second embodiment of the present invention; FIG. 5 is a cross-sectional view of a tripod-type constant velocity universal joint according to a third embodiment of the present invention; FIG. 10 is a cross-sectional view showing a modification in which one side of the track groove has no flange;

A tripod type constant velocity universal joint according to a first embodiment of the present invention is shown in FIGS. First, the overall configuration of the tripod type constant velocity universal joint of the present embodiment will be described with reference to FIGS. 1 to 6. FIG. FIG. 1 is a vertical cross-sectional view of a tripod type constant velocity universal joint according to this embodiment, and FIG. 2 is a cross-sectional view taken along line AA in FIG. However, in FIG. 2, the tripod member 3 and the two lower roller units 4 are not shown in cross section, and the illustration of the shaft 9 is omitted. 3 is a plan view of the roller unit and the leg shaft taken along the line BB of FIG. 1, and FIG. 4 is a longitudinal sectional view of the roller unit taken along the line EE of FIG. 5 is a longitudinal sectional view showing a state in which the tripod-type constant velocity universal joint of FIG. 1 has a normal working angle, and FIG. 6 shows a state in which the tripod-type constant velocity universal joint of FIG. 1 has a working angle larger than the normal working angle. It is a longitudinal cross-sectional view showing a state.

As shown in FIGS. 1 and 2, the tripod type constant velocity universal joint 1 is mainly composed of an outer joint member 2, a tripod member 3 as an inner joint member, and a roller unit 4 as a torque transmission member. ing. The outer joint member 2 has a cup portion 2a with one end open, and three linear track grooves 5 extending in the axial direction are formed on the inner peripheral surface at equal intervals in the circumferential direction. Circumferentially opposed roller guide surfaces 6 are formed, each extending in the axial direction. A tripod member 3 and a roller unit 4 are housed inside the outer joint member 2 .

The tripod member 3 has three radially projecting leg shafts 7 . A shaft 9 is spline-fitted into the center hole 8 of the tripod member 3 and fixed in the axial direction by a retaining ring 10 . The roller unit 4 includes a roller 11, an inner ring 12 disposed inside the roller 11 and fitted on the leg shaft 7, and a plurality of needle rollers 13 interposed between the roller 11 and the inner ring 12. The main part is composed of The roller unit 4 is accommodated in the track groove 5 of the outer joint member 2 , and the center of the roller unit 4 (roller 11 ) in the width direction is positioned on the pitch circle PC of the track groove 5 .

As shown in FIG. 4, the needle rollers 13 are arranged between the cylindrical inner peripheral surface 11b of the roller 11 and the cylindrical outer peripheral surface 12b of the inner ring 12 in a so-called full roller state without a retainer. The cylindrical inner peripheral surface 11b of the roller 11 is used as an outer raceway surface, and the cylindrical outer peripheral surface 12b of the inner ring 12 is used as an inner raceway surface. The inner peripheral surface 12a of the inner ring 12 forms an arc-shaped convex surface in a longitudinal section including the axis of the inner ring 12. As shown in FIG. This arc-shaped convex surface has a curvature radius ri of, for example, about 30 mm in order to allow the leg shaft 7 to be inclined by about 2 to 3° with respect to the inner ring 12 due to whirling unique to tripod type constant velocity universal joints. ing.

The outer peripheral surface 11a of the roller 11 is formed of a partial spherical surface with a radius of curvature r centered on the axis 4x of the roller unit 4, in other words, on the axis 7x of the leg shaft 7 shown in FIG. The roller unit 4 composed of the inner ring 12 of the roller unit 4, the needle rollers 13 and the rollers 11 is constructed so as not to be separated by the

washers

14 and 15. As shown in FIG. The

washers

14 and 15 are divided at one point in the circumferential direction (see FIG. 3), and are fitted in the annular groove of the cylindrical inner peripheral surface 11b of the roller 11 in an elastically contracted state. ing.

As shown in FIGS. 1 and 2, the outer peripheral surface 7a of each leg shaft 7 of the tripod member 3 has a straight shape in a longitudinal section including the axis 7x of the leg shaft 7 (see FIG. 3). In addition, as shown in FIG. 3, the outer peripheral surface 7a of the leg shaft 7 has a substantially elliptical shape in a cross section perpendicular to the axis 7x of the leg shaft 7, and extends in the direction perpendicular to the axis of the joint, that is, the direction of the major axis a. A gap m is formed with the inner peripheral surface 12a of the inner ring 12 in the axial direction of the joint, that is, in the direction of the minor axis b. In the tripod type constant velocity universal joint 1 , the rollers 11 of the roller unit 4 attached to the leg shafts 7 of the tripod members 3 roll on the roller guide surfaces 6 of the track grooves 5 of the outer joint member 2 .

Since the cross section of the leg shaft 7 is substantially elliptical, the axis of the tripod member 3 is inclined with respect to the axis of the outer joint member 2 as shown in FIG. The unit 4 is tiltable with respect to the axis of the leg shaft 7 of the tripod member 3 . Therefore, the rollers 11 of the roller unit 4 and the roller guide surface 6 are prevented from being in an oblique state, and they roll properly, so that the induced thrust and the slide resistance can be reduced, and the vibration of the joint can be reduced. can be realized. In this specification and the scope of claims, the substantially elliptical shape is not limited to a literal elliptical shape, and includes shapes generally called an egg shape, an oval shape, and the like.

Since the leg shaft 7 having a substantially elliptical cross section and the inner ring 12 having a circular inner peripheral surface 12a come into contact with each other to transmit torque, the surface pressure of the contact portion between the leg shaft 7 and the inner ring 12 is relieved. In order to secure the strength of the leg shaft 7, the ellipticity b/a of the major axis a and the minor axis b of the substantially elliptical shape of the leg shaft 7 and the curvature radius ri of the inner peripheral surface 12a of the inner ring 12 (see FIG. 4) is set. Therefore, at relatively small working angles that are commonly used, the roller unit 4 can be tilted with respect to the leg shaft 7 as described above with reference to FIG. It can roll without crossing.

On the other hand, when the operating angle exceeds a predetermined angle (for example, about 15°) exceeding the normal operating angle, the outer peripheral surface 7a of the leg shaft 7 and the inner peripheral surface 12a of the inner ring 12 shown in FIG. (Roller 11) can no longer incline with respect to the leg shaft 7. Since the angle at which the roller unit 4 can be tilted with respect to the leg shaft 7 is limited, the roller unit 4 must be tilted with respect to the track groove 5 by the insufficient angle when the angle is larger than the predetermined angle exceeding the normal operating angle. However, as shown in FIG. 4, the outer peripheral surface 11a of the roller 11 is formed by a partial spherical surface having a curvature radius r centered on the axis 7x of the leg shaft 7. Therefore, as shown in FIG. , the roller unit 4 can be tilted within the track groove 5, so that a large working angle can be accommodated.

The overall configuration of the tripod type constant velocity universal joint 1 of this embodiment is as described above. Next, a characteristic configuration will be described. Characteristic configurations are the following (1) to (4).
(1) With respect to the center of the slide range in the joint axial direction of the track groove, the range from 10 mm on the back side to 10 mm on the opening side is defined as the center range, and the track diameter, which is the width dimension between the roller guide surfaces, is defined in the center range. Forming a part where is the smallest.
(2) A track gap is formed between the roller guide surface and the outer peripheral surface of the roller in the central area.
(3) The minimum value of the track clearance of the three track grooves in the central range is set to 0.010 mm or more and 0.100 mm or less.
(4) The mutual difference in the track diameters of the three track grooves in the central range is 0.150 mm or less.

The above characteristic configurations (1) to (4) were reached through the following examination process. That is, the inventors found that (a) precision levels at the limits of forging and heat treatment, (b) efficient feasibility of roller selection combinations for track diameters, (c) durability, strength, and NVH properties (low Circumferential direction backlash in the center range of the joint axial direction of the track groove, which is the slide range most frequently used in actual vehicles equipped with tripod type constant velocity universal joints, was investigated. is the key to the solution, and the new idea of setting the minimum value of the track clearance and the mutual difference between the track diameters in the center range is used to achieve the above characteristic configuration (1) to (4) is reached.

The characteristic configuration will be explained in order with reference to the drawings. The characteristic configuration (1) is to precisely form the track clearance in the central range of the joint axial direction of the track groove, which is the slide range most frequently used in actual vehicles equipped with tripod type constant velocity universal joints. A portion is formed in the range where the track diameter, which is the width dimension between the roller guide surfaces, is the smallest. Characteristic configuration (1) will be specifically described with reference to FIGS. 7a and 7b. 7a shows the details of the track grooves of the outer joint member in FIG. 1 in the joint axial direction, and is a cross-sectional view taken along line ZZ in FIG. 7b, and FIG. 7b is a vertical cross-sectional view.

The outer joint member of the sliding tripod type constant velocity universal joint is generally manufactured through a forging process, a cutting process, a quenching process, and a grinding process, and the inside of the cup portion is finished by cold forging (grinding after the quenching process). No finish processing is applied in the process, etc.). In the forging process and the heat treatment process, as shown in FIG. 7a, a portion 6a in which the track diameter L, which is the width dimension between the roller guide surfaces 6, is minimized is formed in the center range W of the track groove in the joint axial direction. A portion 6a formed in the central range W where the track diameter L is the smallest serves as a reference for setting the track clearance δ and the track diameter L, which will be described later.

As shown in FIGS. 7a and 7b, the central range W is located on the back side of the sliding range central portion C of the track groove 5 of the outer joint member 2 in the joint axial direction. The range is from w (=10 mm) to w (=10 mm) on the opening side. As shown in FIG. 7a, a portion 6a having the smallest track diameter L is formed in the central range W, and the track diameter L gradually decreases from the opening side of the cup portion 2a to the sliding range central portion C (central range W). , and gradually increases from the slide range central portion C (central range W) toward the back side. The variation dimension of the track diameter L gradually varying in the axial direction is about 0.100 mm to 0.300 mm.

Here, the sliding range central part C is defined. The slide range central portion C is arbitrarily set according to the vehicle use conditions. In other words, the slide range central portion C may deviate from the central position of the entire area from the opening of the cup portion 2a to the bottom portion of the cup portion. Therefore, the center of axial displacement of the roller unit 4 during general vehicle travel is defined as the slide range center C. As shown in FIG. Based on the slide range center C, the area that can be used at all times during general vehicle running is "slide range center C ± 10 mm". stipulate. The sliding range central portion of the track groove in the joint axial direction in the present specification and claims has the above meaning. FIG. 13 shows a modification of the bottom shape of the cup portion 2a of the track groove of FIG. 7a. In this modification, the bottom shape of the cup portion 2a is formed in a concave circular arc shape along the outer peripheral surface 11a of the roller 11. As shown in FIG. Also in this modified example, the slide range center portion C and the center range W are the same.

A characteristic configuration (2) is that a track clearance δ is formed between the roller guide surface 6 in the central range W and the outer diameter surface (outer peripheral surface 11a) of the roller 11 . As shown in FIG. 7a, a positive track clearance .delta. As a result, it is easy to handle due to sliding resistance when mounted on the vehicle, and it is possible to suppress the backlash in the circumferential direction in the area that is most frequently used in the vehicle, ensuring NVH characteristics (low vibration characteristics). can. Note that the track clearance δ is shown in an exaggerated manner.

The track clearance δ of the track grooves 5 in the central range W will be explained based on FIG. FIG. 8 is an enlarged cross-sectional view in the central region W of FIGS. 7a and 7b. In FIG. 8 , the centerline 5x of the track groove 5 and the axis 7x of the leg shaft 7 are shown aligned, and only the cross section of the outer joint member 2 and the side view of the roller 11 are shown.

As shown in FIG. 8, the outer peripheral surface 11a of the roller 11 is formed of a partial spherical surface with a radius of curvature r with the center of curvature Or on the axis 7x of the leg shaft 7. The roller guide surface 6 passes through the intersection T between the pitch circle PC of the track groove 5 and the center line 5x of the track groove 5, and has the center of curvature OR at a position beyond the center line 5x of the track groove 5 on the line of the contact angle α. It is formed with a Gothic arch-shaped cross-section with a radius of curvature R and extends parallel to the axis of the joint. The curvature radius R is set appropriately larger than the curvature radius r. Therefore, the outer peripheral surface 11a of the roller 11 and the roller guide surface 6 form an angular contact at two points with a contact angle α with respect to the horizontal line XX passing through the intersection point T. As shown in FIG.

Of the three track grooves 5, for example, the upper track groove 5 is designated as the first track groove 5(1), and the track groove 5 positioned 120° clockwise from the first track groove 5(1) is designated as the second track groove. and the track groove 5 located 240° clockwise from the first track groove 5(1) is defined as the third track groove 5(3). As described above, the track diameter L and the track clearance δ vary among the three track grooves 5 due to cold forging finishing (no grinding finishing after heat treatment) and heat treatment deformation. In the first track groove 5(1), the track diameter is L1 and the track clearance is .delta.1. The second track groove 5(2) has a track diameter of L2 and a track clearance of .delta.2. The third track groove 5(3) has a track diameter of L3 and a track clearance of δ3.

Here, we will explain how to assign symbols. When the three track grooves are not specified, reference numeral 5 is assigned, and reference numerals 5(1) to 5(3) are assigned to the first to third track grooves, respectively. When the three track diameters are not specified, L is given, and the track diameters of the first to third track grooves are given L1 to L3. Similarly, when the three track clearances are not specified, the reference numeral δ is attached, and the reference numerals δ1 to δ3 are attached to the respective track clearances of the first to third track grooves. The maximum value of the track diameter L is denoted by Lmax, and the minimum value thereof is denoted by Lmin. The maximum value of the track clearance δ is denoted by δmax, and the minimum value thereof is denoted by δmin.

Among the three track grooves 5 in the central range W, the track diameter L1 and the track clearance δ1 of the first track groove 5(1) are the minimum values, the track diameter L1 is the minimum value Lmin, and the track clearance δ1 is the minimum value. is the value .delta.min. The track diameter L2 and the track clearance δ2 of the second track groove 5(2) are the maximum values, the track diameter L2 is the maximum value Lmax, and the track clearance δ2 is the maximum value δmax.

An enlarged view of the first track groove 5(1) in FIG. 8 is shown in FIG. As shown in FIG. 9, the track diameter L1 of the first track groove 5(1) is the minimum value Lmin, and the track clearance .delta.1 is the minimum value .delta.min. An enlarged view of the second track groove 5(2) is shown in FIG. The track diameter L2 of the second track groove 5(2) is the maximum value Lmax, and the track clearance .delta.2 is the maximum value .delta.max. Production technology development has been continuously conducted, but there is a limit to the accuracy of the track grooves 5 that are deformed by cold forging and subsequent heat treatment inside the cup portion 2a of the outer joint member. 8, 9 and 10, the track diameter L and the track clearance δ are exaggerated.

Fig. 11 shows the case of circular contact. FIG. 11 is a partial cross-sectional view showing the minimum value .delta.min of the track clearance .delta. in the case of circular contacts. In the case of a circular contact, the roller guide surface 6 of the track groove 5 has a curvature that places the center of curvature OR' on the horizontal line XX passing through the intersection T between the center line 5x of the track groove 5 and the pitch circle PC of the track groove 5. It is formed in a partial cylindrical shape with a radius R'. The roller guide surface 6 and the roller 11 come into contact with each other about the horizontal line XX passing through the intersection point T as the center. The circular contact can be applied in the same manner as the angular contact.

As described with reference to FIG. 8 , the track diameter L, which is the width dimension between the roller guide surfaces 6 , varies among the three track grooves 5 . That is, between the three track grooves 5, the difference between the maximum value Lmax and the minimum value Lmin of the track diameter L becomes large. The difference between the maximum value Lmax and the minimum value Lmin of the three track grooves 5 of the track diameter L is called the mutual difference of the track diameter L. Mutual differences in track diameters in this specification and claims are used in this sense. The mutual difference in the track diameters L affects variations in the track clearance δ between the roller guide surface 6 and the outer peripheral surface 11 a of the roller 11 . That is, between the three track grooves 5, the difference between the maximum value δmax and the minimum value δmin of the track clearance δ is affected. Therefore, it was found that the minimum value .delta.min of the track clearance .delta.

As a result of various examinations and verifications, it was found that the maximum value δmax of the track clearance δ in the central range W is 0.250 mm. It has been found that if the track clearance δ exceeds 0.250 mm, a clattering sound or the like occurs when a torque load is applied, and NVH characteristics (low vibration characteristics) cannot be ensured.

A characteristic configuration (3) is that the minimum value δmin of the track clearance δ between the three track grooves 5 in the central range W is set to 0.010 mm or more and 0.100 mm or less.

By setting the minimum value δmin of the track clearance δ to 0.010 mm or more, the rollers 11 can slide smoothly in the track grooves 5 without unnecessary interference. In addition, the track clearance δ in the central range W of the slide range, which is most frequently used in actual vehicles, is minimized, so that the circumferential play can be suppressed, and durability, strength, and NVH characteristics (low vibration characteristics) can be ensured.

In addition, by setting the minimum value δmin of the track clearance δ to 0.100 mm or less, it becomes possible to receive a load in a well-balanced manner between the roller guide surfaces 6, the rollers 11, and the leg shafts 7 of the tripod members 3, resulting in durability. The durability, strength, and NVH characteristics (low vibration characteristics) can be ensured.

Furthermore, by setting the minimum value δmin of the track clearance δ to 0.010 mm or more and 0.100 mm or less, it is possible to practically select and combine rollers for the track grooves of the outer joint member. That is, the minimum value δmin of the track clearance δ has a width of 0.090 mm between the lower limit value 0.010 mm and the upper limit value 0.100 mm. It is possible to practically select and combine a suitable number of rank rollers 11 (roller unit 4).

Specifically, a method of selecting and combining the rollers 11 (roller unit 4) with respect to the track grooves 5 of the outer joint member 2 will be described. A minimum value Lmin of the track diameter L is measured in the central range W of the track groove 5 of the outer joint member 2 . As a result, a roller unit 4 having an outer diameter satisfying 0.010 mm to 0.100 mm, which is the minimum value δmin of the track clearance δ, is selected for the track diameter L of the minimum value Lmin. Then, the selected three roller units 4 having the same outer diameter are inserted into all three track grooves 5 including the track groove 5 having the minimum track diameter L of Lmin. The outer diameter tolerance width of the selected three roller units 4 having the same outer diameter is about 0.020 mm. Therefore, the outer diameter dimensions of the three roller units 4 inserted into the track grooves 5 of one outer joint member 2 can be considered to be substantially the same when compared with the value of the mutual difference between the track diameters L. .

Therefore, only the range of 0.010 mm to 0.100 mm, which is the minimum value δmin of the track clearance, is in a relationship to substantially change the upper limit value 0.250 mm of the maximum value δmax of the track clearance δ in the central range W described above. . As a result, in order to secure the upper limit value of 0.250 mm for the maximum value δmax of the track clearance δ in the central range W, the upper limit value of 0.100 mm from 0.010 mm to 0.100 mm, which is the minimum value δmin of the track clearance, is required. 0.150 mm subtracted from the upper limit of 0.250 mm of the maximum value δmax of the clearance δ should be set as the upper limit of the mutual difference between the track diameters L of the three track grooves 5 in the central range W. Configuration (4) is derived.

A characteristic configuration (4) is that the mutual difference between the track diameters L of the three track grooves 5 in the central range W is 0.150 mm or less. The track diameter L2 of the second track groove 5(2) shown in FIGS. 8 and 10 is the maximum value Lmax, and the track diameter L1 of the first track groove 5(1) shown in FIGS. 8 and 9 is the minimum value. is Lmin. The mutual difference in track diameter L is the difference between the maximum value Lmax and the minimum value Lmin.

As described above, since the mutual difference between the track diameters L is set to 0.150 mm or less, the upper limit of the maximum value δmax of the track clearance δ is set to 0.010 mm to 0.100 mm, which is the minimum value δmin of the track clearance δ. A value of 0.250 mm can be secured. Since the upper limit value of the maximum value δmax of the track clearance δ in the central range W is set to 0.250 mm, it is possible to suppress the occurrence of rattling noise when a torque load is applied.

The non-uniform load on each axle due to the mutual difference in the track clearance δ will be explained based on FIG. 12 . FIG. 12 is a schematic diagram assuming the mutual difference D of the track clearance δ of the third track groove 5(3) with respect to the first track groove 5(1) in one cross section. The first track groove 5(1) and the third track groove 5(3) are centered on the track groove pitch circle PC. The track clearance δ of the first track groove 5(1) is reduced, and the first track groove 5(1) is formed in the state of a dashed line in which the center O2 of the outer joint member 2 and the center O3 of the tripod member 3 are aligned. When the tripod member 3 is rotated by θs by the mutual difference D of the track clearance δ, the center O2 of the outer joint member and the center O3′ of the tripod member are shifted as indicated by the solid line. As a result, the lengths h1, h2, and h3 of the leg shafts with respect to the pitch circle PC of the track grooves change, and the load on each leg shaft becomes uneven.

To summarize the above, the characteristic configurations (1) to (4) together make it possible to practically select and combine rollers for the track diameter of the outer joint member based on the practical accuracy level of forging and heat treatment, and It is easy to handle due to sliding resistance when mounted on a vehicle, and can suppress backlash in the circumferential direction in the central range W of the slide range that is most frequently used in an actual vehicle. NVH characteristics (low vibration characteristics) can be secured.

A tripod type constant velocity universal joint according to a second embodiment of the present invention will be described with reference to FIG. FIG. 14 is a cross-sectional view of the tripod type constant velocity universal joint of this embodiment. However, the lower two rollers and the tripod member are not shown in cross section, and the illustration of the shaft is omitted. This embodiment is a single-roller type tripod type constant velocity universal joint, which is different from the double-roller type of the first embodiment in that it is a single-roller type. Parts having similar functions are denoted by the same reference numerals, and the main points will be explained.

As shown in FIG. 14, this tripod type constant velocity universal joint 1 includes an outer joint member 2, a tripod member 3 as an inner joint member, and a roller 11 as a torque transmission member. The outer joint member 2 has a cup portion 2a with one end open, and three linear track grooves 5 extending in the axial direction are formed on the inner peripheral surface at equal intervals in the circumferential direction. Circumferentially opposed roller guide surfaces 6 are formed, each extending in the axial direction. Inside the outer joint member 2, the tripod member 3 and the roller 11 are accommodated.

The tripod member 3 has three radially projecting leg shafts 7 . The roller 11 is wrapped around the cylindrical outer peripheral surface 7a of the leg shaft 7 via a plurality of needle rollers 13, and is rotatably supported by the leg shaft 7. As shown in FIG. The cylindrical outer peripheral surface 7a of the leg shaft 7 constitutes the inner raceway surface of the needle rollers 13, and the cylindrical inner circumferential surface 11a of the roller 11 constitutes the outer raceway surface of the needle rollers 13. As shown in FIG. The roller 11 has a spherical outer peripheral surface 11 a with a curvature radius r centered on the axis 7 x of the leg shaft 7 . For the contact between the outer peripheral surface 11a of the roller 11 and the roller guide surface 6, both the angular contact and the circular contact described in the first embodiment can be applied.

A plurality of needle rollers 13 are incorporated between the cylindrical outer peripheral surface 7a of the leg shaft 7 and the cylindrical inner peripheral surface 11a of the roller 11 in a full roller state. The needle rollers 13 are radially in contact with an inner washer 15 that is wrapped around the base of the leg shaft 7 and are in contact with an outer washer 14 that is wrapped around the tip of the leg shaft 7 at a radially outer side. . The outer washer 14 is retained by fitting a snap ring 21 into an annular groove 20 formed at the tip of the leg shaft 7 . The outer washer 14 is composed of a disk portion 14a extending in the radial direction of the leg shaft 7 and a cylindrical portion 14b extending in the axial direction of the leg shaft 7. As shown in FIG. The cylindrical portion 14b of the outer washer 14 has an outer diameter smaller than the inner peripheral surface 11a of the roller 11, and the outer end portion 14c of the cylindrical portion 14b seen in the radial direction of the tripod member 3 is equal to the inner peripheral surface 11a of the roller 11. formed with a larger diameter than Therefore, the roller 11 can move in the axial direction of the leg shaft 7 and is prevented from falling off by the end portion 14c.

In the single-roller type tripod-type constant velocity universal joint 1 of the present embodiment, as well as the double-roller-type tripod-type constant velocity universal joint 1 of the first embodiment described above, the following characteristic configuration (1) (4) is provided.
(1) With respect to the center of the slide range in the joint axial direction of the track groove, the range from 10 mm on the back side to 10 mm on the opening side is defined as the center range, and the track diameter, which is the width dimension between the roller guide surfaces, is defined in the center range. Forming a part where is the smallest.
(2) A track gap is formed between the roller guide surface and the outer peripheral surface of the roller in the central area.
(3) The minimum value of the track clearance of the three track grooves in the central range is set to 0.010 mm or more and 0.100 mm or less.
(4) The mutual difference in the track diameters of the three track grooves in the central range is 0.150 mm or less.

Combined with the above characteristic configurations (1) to (4), based on the practical accuracy level of forging and heat treatment, it is possible to practically select and combine rollers for the track diameter of the outer joint member, and to the vehicle. It is easy to handle due to the sliding resistance when installed, and it is possible to suppress the circumferential play in the central range W of the slide range that is most frequently used in the actual vehicle, durability, strength, NVH characteristics ( low vibration characteristics) can be ensured. The characteristic configurations (1) to (4) described above for the tripod-type constant velocity universal joint 1 of the first embodiment are the same for the tripod-type constant velocity universal joint 1 of the present embodiment, so they apply mutatis mutandis. do.

A tripod type constant velocity universal joint according to a third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a cross-sectional view of the tripod type constant velocity universal joint of this embodiment. However, the lower two rollers and the tripod member are not shown in cross section, and the illustration of the shaft is omitted. This embodiment is a double-roller type tripod-type constant velocity universal joint, but differs from the double-roller-type tripod-type constant velocity universal joint 1 of the first embodiment in the shape of the leg shaft and the shape of the roller unit. . Parts having similar functions are denoted by the same reference numerals, and the main points will be explained.

As shown in FIG. 15, in the tripod type constant velocity universal joint 1 of the present embodiment, the outer peripheral surface 7a of the leg shaft 7 of the tripod member 3 is formed in a spherical shape, and the inner ring 12 of the roller unit 4 is formed in a cylindrical inner peripheral shape. The cylindrical inner peripheral surface 12a of the inner ring 12 is slidably supported on the spherical outer peripheral surface 7a of the leg shaft 7 of the tripod member 3. As shown in FIG. The outer peripheral surface 11a of the roller 11 is formed in an annular shape with a relatively small radius of curvature r with the center of curvature positioned at a position Or offset in the radial direction from the axis 7x of the leg shaft 7 . Since other configurations are the same as those of the first embodiment, portions having similar functions are denoted by the same reference numerals, and the main points will be described.

The main part of the roller unit 4 is composed of a roller 11, an inner ring 12, and a plurality of needle rollers 13 incorporated between the roller 11 and the inner ring 12 in a full complement state. The roller unit 4 is accommodated in the track groove 5 of the outer joint member 2 , and the center of the roller unit 4 (roller 11 ) in the width direction is positioned on the pitch circle PC of the track groove 5 .

The tripod member 3 has three radially projecting leg shafts 7 . The outer peripheral surface 7a of the leg shaft 7 is formed in a spherical shape with the center of curvature on the axis 7x of the leg shaft 7, and the cylindrical inner peripheral surface 12a of the inner ring 12 of the roller unit 4 slides on the spherical outer peripheral surface 7a. It is movably attached to the outside. When the joint takes an operating angle, the roller unit 4 can be tilted with respect to the axis of the leg shaft 7 of the tripod member 3 and can move in the axial direction. Therefore, the roller 11 of the roller unit 4 and the roller guide surface 6 can be prevented from being obliquely crossed, and can roll correctly.

The roller guide surface 6 is on the horizontal line XX passing through the intersection T between the pitch circle PC of the track groove 5 and the center line 5x of the track groove 5, and is radially offset from the center line 5x of the track groove 5. It is formed by a partial cylindrical surface with a relatively small radius of curvature R centered at OR and extending parallel to the axis of the joint. In the present embodiment, the flange portion 5a is provided on one side of the track groove 5, but the flange portion may not be provided on one side of the track groove 5 as in the modification shown in FIG.

In the tripod type constant velocity universal joint 1 of the present embodiment, as in the double roller type tripod type constant velocity universal joint 1 of the first embodiment described above, the following characteristic configurations (1) to (4) It has
(1) With respect to the center of the slide range in the joint axial direction of the track groove, the range from 10 mm on the back side to 10 mm on the opening side is defined as the center range, and the track diameter, which is the width dimension between the roller guide surfaces, is defined in the center range. Forming a part where is the smallest.
(2) A track gap is formed between the roller guide surface and the outer peripheral surface of the roller in the central area.
(3) The minimum value of the track clearance of the three track grooves in the central range is set to 0.010 mm or more and 0.100 mm or less.
(4) The mutual difference in the track diameters of the three track grooves in the central range is 0.150 mm or less.

Combined with the above characteristic configurations (1) to (4), based on the practical accuracy level of forging and heat treatment, it is possible to practically select and combine rollers for the track diameter of the outer joint member, and to the vehicle. It is easy to handle due to the sliding resistance when installed, and it is possible to suppress the circumferential play in the central range W of the slide range that is most frequently used in the actual vehicle, durability, strength, NVH characteristics ( low vibration characteristics) can be ensured. The characteristic configurations (1) to (4) described above for the tripod-type constant velocity universal joint of the first embodiment are the same for the tripod-type constant velocity universal joint of the present embodiment, and therefore apply mutatis mutandis.

The present invention is by no means limited to the embodiments described above, and can of course be embodied in various forms without departing from the gist of the present invention. and includes equivalent meanings and all changes within the scope of the claims.

1 tripod type constant velocity universal joint 2 outer joint member 3 tripod member 4 roller unit 5 track groove 5x center line of track groove 6 roller guide surface 6a portion where track diameter is smallest 7 leg shaft 7x leg shaft axis 11 roller 11a outer periphery Surface 12 Inner ring 12a Inner peripheral surface 13 Needle roller C Center of slide range L Track diameter Lmax Maximum track diameter Lmin Minimum track diameter PC Track groove pitch circle T Intersection point W Center range XX Horizontal line a Major axis b Minor axis m Gap α Contact angle δ Track clearance δmax Maximum track clearance δmin Minimum track clearance

Claims

An outer joint member formed with three track grooves having roller guide surfaces arranged opposite in the circumferential direction, a tripod member having three radially protruding leg shafts, and a track of the outer joint member. A tripod type constant velocity universal joint comprising: a torque transmission member supported by the leg shaft;
A range from 10 mm on the back side to 10 mm on the opening side with respect to the center of the slide range of the track groove in the joint axial direction is defined as a center range, and the track diameter, which is the width dimension between the roller guide surfaces, is the minimum in the center range. Forming a part that becomes
A track clearance is formed between the roller guide surface and the outer peripheral surface of the roller in the central area, and the minimum value of the track clearance of the three track grooves in the central area is 0.010 mm or more and 0.100 mm or less. Along with
A tripod type constant velocity universal joint, wherein a mutual difference in track diameters of the three track grooves in the central region is 0.150 mm or less.
The tripod type constant velocity universal joint according to claim 1, characterized in that the mutual difference in the track diameters of the three track grooves in the central region is 0.100 mm or less.
An inner ring that rotatably supports the roller is provided, the inner ring is fitted onto the leg shaft, and the roller is movable along the roller guide surface in the axial direction of the outer joint member. The tripod type constant velocity universal joint according to claim 1 or 2.
The inner peripheral surface of the inner ring is formed into an arc-shaped convex surface in the longitudinal section of the inner ring, the outer peripheral surface of the leg shaft is straight in the longitudinal section including the axis of the leg shaft, and the leg The cross section perpendicular to the axis of the shaft has a substantially elliptical shape, and the outer peripheral surface of the leg shaft abuts the inner peripheral surface of the inner ring in the direction perpendicular to the axis of the joint, and the axial direction of the joint. 4. The tripod type or the like according to any one of claims 1 to 3, wherein a clearance is formed between the roller and the inner peripheral surface of the inner ring, and the roller can be tilted within the track groove. Quick universal joint.
The tripod type constant velocity universal joint according to claim 3 or 4, characterized in that a plurality of rolling elements are arranged between the inner ring and the roller.
The tripod type constant velocity universal joint according to claim 5, wherein the rolling elements are needle rollers.
The tripod type constant velocity universal joint according to claim 1, characterized in that said roller and said roller guide surface are in angular contact.
The tripod type constant velocity universal joint according to claim 1, characterized in that said rollers and said roller guide surfaces are in circular contact.