JP2007182973A - Constant velocity universal joint and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve durability, by improving lubricity of grease inside of a roller mechanism. <P>SOLUTION: This constant velocity universal joint has an outer ring forming three track grooves in the axial direction in an inner peripheral part and having respectively a roller guide surface in the axial direction on both sides of the respective track grooves, a tripod member having three leg shafts projecting in the radial direction and forming a cross section of its leg shafts in a substantially elliptic shape having the major axis orthogonal to the axis of a joint, and the roller mechanism 37 respectively installed on the respective leg shafts of the tripod member and freely oscillating and rocking to the leg shafts. The roller mechanism 37 is an assembly body including a plurality of roller parts 32, 34 and 36, and when assembling the roller mechanism 37, the grease 39 is sealed in a sealed space 38 formed among the roller parts 32, 34 and 36. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a constant velocity universal joint and a method of manufacturing the same, and more specifically, is a type of a sliding type constant velocity universal joint that allows axial displacement and angular displacement between two axes of a driving side and a driven side, for example, an automobile, The present invention relates to a tripod type constant velocity universal joint suitable for use in a power transmission section of an aircraft, a ship, various industrial machines, and the like, and a method for manufacturing the same.

  For example, a tripod type constant velocity universal joint is one type of constant velocity universal joint used as a means for transmitting rotational force from an automobile engine to wheels at a constant speed. This tripod type constant velocity universal joint connects two shafts on the drive side and the driven side, transmits rotational torque at a constant speed even if the two shafts take an operating angle, and also allows relative displacement in the axial direction. It has a structure that can

  In general, a tripod type constant velocity universal joint has three outer track grooves formed in the axial direction on the inner periphery, and an outer ring as an outer member having an axial roller guide surface on each side of each track groove. The main member includes a tripod member as an inner member having three leg shafts protruding in the radial direction, and a roller rotatably accommodated between the leg shaft of the tripod member and the roller guide surface of the outer ring. Configured as One of the drive side and driven side two shafts is connected to the outer ring, and the other is connected to the tripod member.

  In this way, the leg shaft of the tripod member and the roller guide surface of the outer ring engage with each other in the rotational direction of the two shafts via the roller, so that the rotational torque is transmitted from the drive side to the driven side at a constant speed. Further, when the roller rolls on the roller guide surface while rotating with respect to the leg shaft, the relative axial displacement and angular displacement between the outer ring and the tripod member are absorbed.

  This tripod type constant velocity universal joint has a structure in which a roller is mounted on the outer peripheral surface of the leg shaft via a plurality of needle rollers, and the outer ring and tripod member transmit rotational torque while taking an operating angle. In doing so, the roller and the roller guide surface are in an oblique state with the inclination of the leg shaft, so that slip occurs between the two, and the smooth rolling of the roller is prevented and the induced thrust increases. There's a problem. In addition, there is a problem that the sliding resistance when the outer ring and the tripod member are relatively displaced in the axial direction is increased by the frictional force between the roller and the roller guide surface.

  The induced thrust is the thrust force generated by the friction inside the joint when the constant velocity universal joint is rotated at a certain angle, and in the case of the tripod type, it is mainly strong as a tertiary component. Appear. The slide resistance is a sliding joint such as a tripod type constant velocity universal joint, and means a magnitude of an axial friction force generated when the outer ring and the tripod member slide relative to each other.

  In order to solve the above-described problem that the roller and the roller guide surface are obliquely crossed and to reduce induced thrust and slide resistance, a roller mechanism is provided that allows the roller to tilt and displace axially with respect to the leg shaft. Various tripod type constant velocity universal joints have been proposed.

  As this type of tripod type constant velocity universal joint, an outer roller is rotatably assembled to an inner roller via a plurality of needle rollers to form a roller mechanism (assembly body), and the inner circumferential surface of the inner roller is convex in an arc shape. The structure formed in the cross section and externally fitted on the outer peripheral surface of the leg shaft is known (see, for example, Patent Documents 1 and 2). The needle rollers are arranged between the cylindrical outer peripheral surface of the inner roller and the cylindrical inner peripheral surface of the outer roller in a so-called full roller state, and are prevented from being detached by an annular retaining ring.

  According to this configuration, the roller mechanism can be tilted and displaced in the axial direction with respect to the leg shaft by sliding between the convex curved inner peripheral surface of the inner roller and the convex curved outer peripheral surface of the leg shaft. It is possible to avoid the outer roller and the roller guide surface from being in an oblique state.

  Further, the cross-sectional shape of the leg shaft is in contact with the inner peripheral surface of the inner roller in a direction orthogonal to the joint axis, and a gap is formed between the inner peripheral surface of the inner roller in the axial direction of the joint. The shape is an ellipse, for example.

Accordingly, when the joint takes an operating angle, the leg shaft can be inclined with respect to the outer ring without changing the posture of the roller mechanism. In addition, since the contact ellipse between the outer peripheral surface of the leg shaft and the inner roller approaches the point from the horizontally long, the friction moment for tilting the roller mechanism is reduced. Therefore, the posture of the roller mechanism is always stable, and the outer roller is held parallel to the roller guide surface, so that it can roll smoothly.
JP 2000-320563 A JP 2002-242949 A

  By the way, in the tripod type constant velocity universal joint described above, the outer roller and the inner roller of the roller mechanism are surrounded, that is, surrounded by the inner peripheral surface of the outer roller, the outer peripheral surface of the inner roller, and the retaining ring, and the needle rollers are accommodated. The created space is almost sealed. Therefore, since it is difficult for grease to enter from the outside in this sealed space, the lubricity between the outer roller and the needle roller and between the inner roller and the needle roller is poor, and the outer roller, the needle roller and the inner roller The metal parts made of are in direct contact with each other, which may reduce the durability.

  The roller mechanism described above is an assembly in which an outer roller, needle rollers, and an inner roller are assembled. The needle roller is disposed between the cylindrical outer peripheral surface of the inner roller and the cylindrical inner peripheral surface of the outer roller. Since they are arranged in a so-called full roller state, when there is no grease, there is also a problem that when assembling the assembly body, these needle rollers are unstable and assembly of the assembly body is difficult.

  Therefore, the present invention has been proposed in view of the above-described problems, and the object of the present invention is to provide a constant velocity universal joint that can improve the lubricity of grease inside the roller mechanism and improve the durability. And a manufacturing method thereof.

  As a technical means for achieving the above-described object, the constant velocity universal joint according to the present invention has three track grooves in the axial direction formed in the inner peripheral portion, and an axial roller on each side of each track groove. A tripod member having an outer member having a guide surface, three leg shafts projecting in the radial direction, and having a transverse cross section of the leg shaft substantially elliptical with the major axis orthogonal to the axis of the joint; And a roller mechanism that is swingably swingable with respect to the leg shaft. The roller mechanism is an assembly body including a plurality of roller parts, and is a sealed space formed between the roller parts. It is characterized by encapsulating a lubricant. Here, the “substantially elliptical shape” includes not only the literally elliptical shape but also a shape generally called an oval shape or an oval shape.

  As the roller mechanism in the above-described configuration, the outer roller guided along the roller guide surface in a direction parallel to the axis of the outer member, and the outer periphery of the leg shaft is fitted onto the outer peripheral surface of the leg shaft, and the outer roller is interposed through a plurality of rolling elements. It is possible to apply an assembly body composed of roller parts including an inner roller that rotatably supports the roller. As this rolling element, it is possible to use a needle roller.

  In the constant velocity universal joint according to the present invention, since the lubricant is sealed in the sealed space formed between the roller parts constituting the roller mechanism, it is difficult for the grease to flow from the outside because the roller parts are sealed spaces. Even if it exists, since a lubricant can be held in the sealed space and it can be avoided that the metal roller parts are in direct contact with each other, sufficient lubricity can be ensured.

  In addition, even if grease enters from the outside into the sealed space between the roller parts after a while since the start of the operation of the constant velocity universal joint, immediately after the start of the operation, there is no grease in the sealed space and the roller parts are damaged. There is a possibility of receiving. Therefore, the method for manufacturing a constant velocity universal joint according to the present invention is characterized in that a lubricant is sealed in a sealed space formed between roller parts when the roller mechanism is assembled.

  In this way, the lubricant is present in the sealed space when the roller mechanism is assembled, and the lubricant can be held in the sealed space even immediately after the start of the operation of the constant velocity universal joint. Smooth lubricity can be ensured, and initial damage to the roller parts can be suppressed.

  Furthermore, when the roller mechanism is assembled, if the lubricant is applied to at least one of the roller parts facing the sealed space, the inner roller is inserted after the needle rollers are arranged in the outer roller. Even if it exists, since the position holding of the roller part with respect to the outer roller can be performed with the lubricant, the process or jig for holding the position of the roller part becomes unnecessary.

  According to the present invention, by encapsulating the lubricant in the sealed space formed between the roller parts constituting the roller mechanism, even if it is difficult for the grease to flow from the outside due to the sealed space between the roller parts, Since the lubricant can be held in the sealed space and the metal roller parts can be prevented from coming into direct contact with each other, sufficient lubricity can be ensured and durability can be improved. A constant-velocity universal joint can be provided.

  Also, if the lubricant is sealed in the sealed space between the roller parts when the roller mechanism is assembled, the lubricant will be present in the sealed space when the roller mechanism is assembled, and immediately after the start of the operation of the constant velocity universal joint. Even so, the lubricant can be held in the sealed space, sufficient lubricity can be ensured, initial damage to the roller parts can be suppressed, and reliability can be improved.

  Furthermore, when the roller mechanism is assembled, if the lubricant is applied to at least one of the roller parts facing the sealed space, the inner roller is inserted after the needle rollers are arranged in the outer roller. Even in such a case, since the position of the roller component relative to the outer roller can be maintained with the lubricant, a process or jig for maintaining the position of the roller component is not required, and the assembly of the roller mechanism can be simplified.

  The embodiment of the tripod type constant velocity universal joint according to the present invention will be described in detail below. 1 and 2 show the overall configuration of the constant velocity universal joint, FIG. 3 shows the leg shaft and roller mechanism of the constant velocity universal joint, and FIG. 4 shows the overall configuration of the roller mechanism.

  The tripod type constant velocity universal joint of this embodiment is composed mainly of an outer ring 10 as an outer member and a tripod member 20 as shown in FIGS. 1 and 2, and is a biaxial shaft to be connected on the drive side and the driven side. One of the two is connected to the outer ring 10 and the other is connected to the tripod member 20 so that the rotational torque can be transmitted at a constant speed even when the operating angle is taken, and the relative displacement in the axial direction can be allowed. .

  The outer ring 10 has a substantially cylindrical cup shape with one end opened and the other end closed (see FIG. 2), and one shaft (not shown) is integrally provided at the other end, and the inner circumferential portion is axially arranged. Are formed at intervals of 120 ° around the central axis. Each track groove 12 is formed with a concave curved roller guide surface 14 in the axial direction on the side walls facing each other in the circumferential direction.

  The tripod member 20 has three leg shafts 22 protruding in the radial direction, and is held by serration (spline) fitting on the other shaft (not shown). 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 ring 10, and the outer peripheral surface 34 a of the outer roller 34 has a convex curved shape that fits the roller guide surface 14. Eggplant.

  The outer peripheral surface 34a of the outer roller 34 is a convex curved surface having an arc having a center of curvature at a position away from the axis of the leg shaft 22 in the radial direction, and the cross-sectional shape of the roller guide surface 14 has two radii of curvature. A Gothic arch shape is formed, whereby the outer peripheral surface 34a of the outer roller 34 and the roller guide surface 14 are in angular contact. In FIG. 1, action lines of two contact points that are in angular contact are indicated by a one-dot chain line. Even if the cross-sectional shape of the roller guide surface 14 is tapered with respect to the outer peripheral surface 34a of the convex curved surface of the outer roller 34, the angular contact between them is realized.

  As described above, the angular contact between the outer peripheral surface 34a of the outer roller 34 and the roller guide surface 14 makes the outer roller 34 difficult to shake, so that the posture can be stabilized. In the case where the angular contact is not employed, 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 ring 10, and the cross-sectional shape thereof is a generatrix of the outer peripheral surface 34 a of the outer roller 34. It can also be a corresponding arc.

  The outer peripheral surface 22a of the leg shaft 22 has a straight shape parallel to the axis of the leg shaft 22 when viewed in a longitudinal section, and has an elliptical shape whose major axis is orthogonal to the axis of the joint when viewed in a transverse section. The cross-sectional shape of the leg shaft 22 is substantially elliptical by reducing the wall thickness seen in the axial direction of the tripod member 20. In other words, the cross-sectional shape of the leg shaft 22 is such that the surfaces of the tripod member 20 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.

  On the other hand, the inner peripheral surface 32b of the inner roller 32 has an arcuate convex cross section. Since the cross-sectional shape of the leg shaft 22 is substantially elliptical as described above and a predetermined gap is provided between the leg shaft 22 and the inner roller 32, the inner roller 32 is connected to the leg shaft 22. In addition to being able to move in the axial direction, the head can swing freely with respect to the leg shaft 22. As described above, since the inner roller 32 and the outer roller 34 are unitized so as to be relatively rotatable via the needle rollers 36, the inner roller 32 and the outer roller 34 swing as a unit with respect to the leg shaft 22. It is in a swingable relationship. Here, the swing means that the axes of the inner roller 32 and the outer 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 this constant velocity universal joint, the cross section of the leg shaft 22 is substantially elliptical, and the cross section of the inner peripheral surface 32b of the inner roller 32 is an arcuate convex cross section, so the contact ellipse between them is close to a point. At the same time, the area becomes smaller. Accordingly, the force for tilting the roller mechanism 37 is greatly reduced, and the stability of the posture of the outer roller 34 is further improved. Thereby, the induced thrust and the slide resistance are reduced, and the variation range of these values is also reduced. Therefore, this constant velocity universal joint can set the prescribed values of induced thrust and slide resistance to be small, and can be regulated within the prescribed values with high accuracy.

  An inner roller 32 is fitted on the outer peripheral surface 22 a of the leg shaft 22. The inner roller 32 and the outer roller 34 are unitized via a plurality of rolling elements, for example, needle rollers 36, and constitute a roller mechanism 37 (assembly body) capable of relative rotation. That is, the cylindrical outer peripheral surface 32a of the inner roller 32 is used as the inner raceway surface, and the cylindrical inner peripheral surface 34b of the outer roller 34 is used as the outer raceway surface, and the needle rollers 36 are rollably interposed between these inner and outer raceway surfaces. To do. As shown in FIG. 3, the needle rollers 36 are incorporated in a so-called full roller state without a cage.

  In order to restrict the relative movement of the inner roller 32, needle roller 36 and outer roller 34, which are these roller components, in the axial direction, locking means are provided on both sides in the axial direction of the roller mechanism 37, respectively. Yes. As this locking means, as shown in FIG. 4, a retaining ring 35 is fitted in an annular groove 33 provided on the inner peripheral surface 34 b of the outer roller 34. The retaining ring 35 restricts the relative movement of these members in the axial direction with respect to the outer roller 34 by contacting the end surface of the inner roller 32 and the end surface of the needle roller 36. It has been stopped.

  In this roller mechanism 37, the outer roller 34 and the inner roller 32 are surrounded and bent by the inner peripheral surface 34b of the outer roller 34, the outer peripheral surface 32a of the inner roller 32, and the retaining ring 35, and the needle rollers 36 are accommodated. This space becomes a substantially sealed space 38, making it difficult for grease to enter from the outside.

  Therefore, in order to improve the lubricity of the grease inside the roller mechanism 37, a lubricant, for example, grease 39 is sealed in the sealed space 38. In addition to the grease, oil or solid lubricant can be used as the lubricant. As a means for enclosing the grease 39 in the roller mechanism 37, it is preferable to apply the grease 39 in advance to the inner peripheral surface 34b of the outer roller 34 facing the sealed space 38, for example. The grease 39 may be applied in advance to the outer peripheral surface 32a of the inner roller 32 or the surface 36a of the needle roller 36 in addition to the inner peripheral surface 34b of the outer roller 34, or the outer roller 34, which is a roller component. In addition, it may be applied to at least one of the needle roller 36 or the inner roller 32.

  Thus, by sealing the grease 39 in the sealed space 38 of the roller mechanism 37, the grease 39 can be held in the sealed space 38 even if it is difficult for grease to flow into the sealed space 38 from the outside. Since it is possible to avoid the direct contact between the outer roller 34, the needle roller 36, or the inner roller 32, it is possible to ensure sufficient lubricity.

  On the other hand, even if grease flows from the outside into the sealed space 38 of the roller mechanism 37 after a while from the start of operation of the constant velocity universal joint, the outer roller 34 has no grease in the sealed space 38 immediately after the start of the operation. Since the roller parts may be damaged due to the contact between the needle rollers 36 or the inner rollers 32, the grease 39 is sealed in the sealed space 38 of the roller mechanism 37 when the roller mechanism 37 is assembled. Good.

  By doing so, the grease 39 exists in the sealed space 38 when the roller mechanism 37 is assembled, and the grease 39 can be held in the sealed space 38 even immediately after the start of the operation of the constant velocity universal joint. Thus, sufficient lubricity can be ensured, and initial damage to the outer roller 34, the needle roller 36, or the inner roller 32 can be suppressed.

  Further, when the roller mechanism 37 is assembled, if the grease 39 is applied to at least one of the inner peripheral surface 34b of the outer roller 34 or the surface 36a of the needle roller 36, the inner peripheral surface 34b of the outer roller 34 is provided. Even when the inner roller 32 is inserted after the needle rollers 36 are arranged, the position of the needle rollers 36 can be maintained with the grease 39 because the position of the needle rollers 36 relative to the outer roller 34 can be maintained. No process or jig is required.

In embodiment of this invention, it is a cross-sectional view which shows the whole structure of a tripod type constant velocity universal joint. It is sectional drawing which shows the state which took the operating angle in the longitudinal cross-section of the constant velocity universal joint of FIG. It is sectional drawing which shows the leg axis | shaft and roller mechanism of the tripod member of FIG. It is a principal part enlarged view which shows the roller mechanism of FIG.

Explanation of symbols

10 Outer member (outer ring)
12 Track groove 14 Roller guide surface 20 Tripod member 22 Leg shaft 32 Roller component (inner roller)
34 Roller parts (outer rollers)
36 Roller parts [Rolling elements (needle rollers)]
37 Roller mechanism 38 Sealed space 39 Lubricant (grease)

Claims (5)

  Three track grooves in the axial direction are formed on the inner peripheral part, and an outer member having an axial roller guide surface on each side of each track groove, and three leg shafts projecting in the radial direction, A tripod member whose transverse axis is substantially elliptical with the major axis orthogonal to the axis of the joint, and a roller mechanism that is mounted on each leg shaft of the tripod member and swings freely with respect to the leg shaft And the roller mechanism is an assembly including a plurality of roller parts, and a lubricant is enclosed in a sealed space formed between the roller parts.   The roller mechanism has an outer roller guided along a roller guide surface in a direction parallel to the axis of the outer member, and is fitted on the outer peripheral surface of the leg shaft to rotate the outer roller via a plurality of rolling elements. 2. The constant velocity universal joint according to claim 1, wherein the constant velocity universal joint is an assembly body composed of roller parts including inner rollers that are freely supported.   Three track grooves in the axial direction are formed on the inner peripheral part, and an outer member having an axial roller guide surface on each side of each track groove, and three leg shafts projecting in the radial direction, A tripod member whose transverse axis is substantially elliptical with the major axis orthogonal to the axis of the joint, and a roller mechanism that is mounted on each leg shaft of the tripod member and swings freely with respect to the leg shaft The roller mechanism is a method of manufacturing a constant velocity universal joint that is an assembly including a plurality of roller parts, and a lubricant is formed in a sealed space formed between the roller parts when the roller mechanism is assembled. A method for manufacturing a constant velocity universal joint, wherein   The method for manufacturing a constant velocity universal joint according to claim 3, wherein a lubricant is applied to at least one of the roller parts facing the sealed space when the roller mechanism is assembled.   The roller mechanism has an outer roller guided along a roller guide surface in a direction parallel to the axis of the outer member, and is fitted on the outer peripheral surface of the leg shaft to rotate the outer roller via a plurality of rolling elements. The manufacturing method of the constant velocity universal joint according to claim 3 or 4 made into an assembly object constituted by roller parts which consist of an inner roller supported freely.

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