JP2010261559A - Trunnion for tripod type constant velocity universal coupling, and tripod type constant velocity universal coupling - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a trunnion for a tripod type constant velocity universal coupling, and the tripod type constant velocity universal coupling using the trunnion capable of smoothly taking its working angle and stable in the strength of leg shafts. <P>SOLUTION: The trunnion 20 has a boss 22 and three leg shafts 24 radially projected from circumferentially equally-divided positions of the boss 22. The outer peripheral surface of each leg shaft 24 is formed with a rolling surface 26a on which a plurality of needle rollers 40 roll. A root of the leg shaft 24 has a thinned part 29 recessed to retreat from the rolling surface 26a of the needle rollers 40. A compressive residual stress treating part is provided on the surface of the thinned part 29. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is used in power transmission systems such as automobiles, airplanes, ships, and various industrial machines, and is incorporated in drive shafts and propeller shafts used in, for example, 4WD vehicles and FR vehicles. The present invention relates to a tripod type constant velocity universal joint and a trunnion of a tripod type constant velocity universal joint which are a kind of sliding type constant velocity universal joints that allow axial displacement and angular displacement between two axes.

  For example, there is a tripod type constant velocity universal joint as one of constant velocity universal joints used as means for transmitting rotational force from an automobile engine to wheels at a constant speed (see, for example, Patent Document 1). 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

  4 and 5 show the structure of the tripod type constant velocity universal joint disclosed in Patent Document 1. FIG. 4 shows a cross section with respect to the axis of the joint, and FIG. 5 shows a vertical section with respect to the axis of the joint.

  The tripod type constant velocity universal joint shown in the same figure includes an outer ring 110 that is an outer joint member, a tripod member (trunnion) 120 that is an inner joint member, and a roller 130 that is a rolling element. One shaft (drive shaft) of the drive side and the driven side to be connected extends integrally from the bottom of the outer ring 110, and the other shaft (not shown) is coupled to the tripod member 120.

  The outer ring 110 has a bottomed cylindrical shape with one end opened, and three track grooves 112 extending in the axial direction are formed at equal intervals in the circumferential direction on the inner circumference thereof. The tripod member 120 has three leg shafts 124 projecting radially outward from the cylindrical boss portion 122, and these leg shafts 124 are inserted into the track grooves 112 of the outer ring 110 and engaged with the track grooves 112. Torque transmission. A roller 130 is rotatably fitted on the leg shaft 124 via a needle roller 140, and the roller 130 rolls along a pair of roller guide surfaces 114 facing each other in the track groove 112, thereby connecting two shafts. Smooth the angular displacement and axial displacement between.

  FIG. 6 is a partially enlarged view of FIG. 4 and shows the leg shaft 124, the needle rollers 140 and the rollers 130. The outer circumferential surface of the leg shaft 124 constitutes the inner rolling surface of the needle roller 140, and the inner circumferential surface of the roller 130 constitutes the outer rolling surface of the needle roller 140. The plurality of needle rollers 140 are disposed between the outer peripheral surface of the leg shaft 124 and the inner peripheral surface of the roller 130 in a full roller state.

  These needle rollers 140 are in contact with the inner washer 150 fitted to the base of the leg shaft 124 inward in the radial direction, and are radially outward with the outer washer 160 fitted in the tip of the leg shaft 124. It touches. The outer washer 160 is prevented from coming off by fitting a retaining ring 170 such as a circlip into an annular groove 126 formed at the tip of the leg shaft 124, and the retaining ring 170 causes the needle roller 140 to move in the radial direction. Movement is restricted.

Japanese Patent No. 3615987

  In the device disclosed in Patent Document 1, the movement of the needle roller 140 in the radial direction is restricted by the inner washer 150 and the outer washer 160. For this reason, in such a constant velocity universal joint, when it is going to take an operating angle, the needle roller 140 cannot move, but this operating angle could not be taken smoothly.

  In view of the above-mentioned problems, the present invention provides a tripod type constant velocity universal joint trunnion that can smoothly take this operating angle and has a stable leg shaft strength, and a tripod type using such a trunnion. Provide constant velocity universal joints.

  The trunnion of the tripod type constant velocity universal joint of the present invention has a boss portion and three leg shafts projecting in a radial direction from the circumferentially equalized position of the boss portion. A trunnion of a tripod type constant velocity universal joint in which a rolling surface on which a plurality of needle rollers roll is formed, so that the root part of the leg shaft is retracted from the rolling surface of the needle roller. A recessed relief portion is provided, and the surface of the relief portion is a compression residual stress treatment portion.

  According to the trunnion of the tripod type constant velocity universal joint according to the present invention, since the base portion of the leg shaft is provided with a hollow portion recessed so as to recede from the rolling surface of the needle roller, By this, the needle rollers can move in the radial direction. In addition, the surface of the thinning portion is a compressive residual stress processing portion. The stress that remains in the material after the external force is removed and is in a compressed state is called compressive residual stress. In general, materials are often damaged by tensile stress, and if there is compressive residual stress, fatigue strength improves.

  The compressive residual stress processing part is used for quenching steel cutting and shot peening after heat treatment, whether it is constituted by quenching steel cutting after heat treatment or shot peening after heat treatment. It may be configured. Hardened steel cutting is simply cutting, and since cutting is usually performed in the state of raw material, it was referred to as hardened steel cutting in order to clarify that the cutting was after heat treatment (after quenching). Since cutting is performed after quenching, the heat treatment deformation of the material can be removed in this cutting process. On the other hand, since grinding requires a grinding fluid during processing, the consumption of mineral oil contained in the grinding fluid and the power consumption of the grinding fluid are enormous, resulting in high costs and adverse environmental impacts. Is concerned. Instead, if hardened steel cutting, which is a dry process, is performed as a finishing process, no grinding oil is required and the burden on the environment is reduced. That is, in the grinding process, powdery grinding waste is generated, and the grinding waste is discharged together with the grinding oil as grinding sludge. The grinding sludge is partly reused as grinding oil after filtering the grinding waste, while the high-concentration sludge obtained by filtration is discarded. As described above, the grinding process requires a supply device and a filtration device related to the grinding oil, so that the device configuration becomes complicated. In addition, the discarded sludge may adversely affect the environment. In addition, preparation for supplying the grinding oil is necessary in the machining operation, and there is a problem that the operation takes time and productivity is low. Note that a cutting tool capable of such cutting is used as a cutting tool. As a cutting tool capable of cutting hardened steel, for example, a sintered tool obtained by adding a special ceramic binder to CBN (cubic boron nitride) can be used.

  Shot peening is a process of projecting small particles onto the surface of the object to be processed, and is performed under the condition that the outermost surface is plastically deformed for the purpose of generating a compressive residual stress on the surface.

  It is preferable that an outer flange is provided on the distal end side in the radial direction of the rolling surface of the leg shaft. In this way, when the outer collar is provided, a trunnion unit in which needle rollers and rollers are assembled to the leg shaft is configured, and when this trunnion unit is attached to the outer joint member of the constant velocity universal joint, the outer collar This restricts the roller from coming out in the radial direction.

  Moreover, even if the entire surface is subjected to carburizing heat treatment, the entire surface may be subjected to induction heat treatment. Here, the carburizing heat treatment is a process in which carbon is impregnated from the surface layer (carburizing treatment) by heating the steel for a long time in a carburizing agent such as a gas, liquid or solid containing a large amount of carbon. It is a method of quenching and tempering steel. In addition, high-frequency heat treatment is a quenching method that applies the principle of heating a conductive object by placing a part necessary for quenching in a coil through which a high-frequency current flows and generating Joule heat by electromagnetic induction. .

  Even if hardened steel cutting is given to the rolling surface of the leg shaft, the rolling surface of the leg shaft may be ground.

  The tripod type constant velocity universal joint of the present invention uses the trunnion of the tripod type constant velocity universal joint described above.

  In the trunnion of the tripod type constant velocity universal joint of the present invention, the needle rollers can move in the radial direction, can take a stable operating angle, and can be operated smoothly. In addition, the leg shaft is excellent in strength and excellent in durability.

  Moreover, the compressive residual stress processing part of a thin part can be shape | molded by hardening steel cutting, shot peening, etc., and can perform the stable compressive residual stress processing. In particular, in hardened steel cutting, if the hardened steel cutting, which is a dry process, is performed in the finishing process, a grinding fluid is unnecessary, and there is an advantage that the burden on the environment is reduced.

  If an outer collar is provided on the radial front end side of the rolling surface of the leg shaft, the outer collar restrains the roller from coming off in the radial front direction. For this reason, during operation of the constant velocity universal joint, the trunnion unit is not disassembled in the outer joint member, and stable operation is possible.

  By performing carburizing heat treatment or high-frequency heat treatment on the entire surface, it exhibits excellent strength and stable functions over a long period of time. Further, by applying hardened steel cutting or grinding to the rolling surface of the leg shaft, the needle rollers roll on the rolling surface more smoothly.

  According to the tripod type constant velocity universal joint using the trunnion described above, smooth operation is possible, the leg shaft is excellent in strength, and durability as a tripod type constant velocity universal joint can be improved. .

It is a cross-sectional view of a tripod type constant velocity universal joint using the trunnion of the embodiment of the present invention. It is a longitudinal cross-sectional view of the tripod type constant velocity universal joint in the said FIG. It is a principal part front view of the said trunnion. It is a cross-sectional view of a tripod type constant velocity universal joint using a conventional trunnion. It is a longitudinal cross-sectional view of the tripod type constant velocity universal joint using the conventional trunnion. It is a principal part expanded sectional view of the tripod type constant velocity universal joint using the conventional trunnion.

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

  1 and 2 show an embodiment of a tripod type constant velocity universal joint according to the present invention. The tripod type constant velocity universal joint according to this embodiment includes a main part including an outer ring 10 that is an outer joint member, a tripod member (trunnion) 20 that is an inner joint member, and a roller 30 that is a rolling element.

  The outer ring 10 has a bottomed cylindrical shape with one end opened, and a rotating shaft (for example, a driving shaft) integrally extends from the center of the bottom. Three track grooves 12 extending in the axial direction are formed on the inner peripheral surface of the outer ring 10 at equal intervals in the circumferential direction. Each track groove 12 has a pair of roller guide surfaces 14 facing each other on both sides thereof. The roller guide surface 14 has an arc-shaped cross section and extends linearly in the axial direction of the outer ring 10. The outer ring 10 has a recess 18 formed in the axial direction by reducing the thickness of a portion corresponding to the space between the track grooves 12 in order to reduce the weight.

  The tripod member (trunnion) 20 is formed by integrally forming three leg shafts 24 projecting outward in the radial direction on the outer peripheral surface of a cylindrical boss portion 22 at equal intervals in the circumferential direction (120 ° intervals). It is. A shaft end of a rotating shaft (not shown) (not shown) is connected to the shaft hole of the boss portion 22 by spline fitting. The tip of each leg shaft 24 extends outward in the radial direction and extends to the vicinity of the bottom surface of the track groove 12, and the outer peripheral surface thereof is generally a cylindrical surface.

  A roller 30 is rotatably disposed via a needle roller 40 between the roller guide surface 14 of the track groove 12 of the outer ring 10 and the outer peripheral surface of the leg shaft 24. The outer peripheral surface of the roller 30 has an arc shape in vertical section, and may contact with the roller guide surface 14 at two locations by angular contact or contact at one location by circular contact. On the other hand, the inner peripheral surface of the roller 30 is formed in a cylindrical shape.

  A roller 30 rotatably mounted on the leg shaft 24 of the tripod member 20 via a needle roller 40 is inserted into and engaged with the track groove 12 of the outer ring 10, and a pair of track grooves 12 facing each other. By rolling along the roller guide surface 14, torque is transmitted while allowing angular displacement and axial displacement between the two connecting shafts (drive shaft and driven shaft).

  The outer circumferential surface of the leg shaft 24 constitutes the inner rolling surface of the needle roller 40, and the inner circumferential surface of the roller 30 constitutes the outer rolling surface of the needle roller 40. A plurality of needle rollers 40 are disposed between the inner peripheral surface of the roller 30 and the outer peripheral surface of the leg shaft 24 in a single row full roller state.

  In the tripod type constant velocity universal joint in this embodiment, the concave groove portion 26 in which the needle roller 40 is accommodated on the outer peripheral surface of the leg shaft 24 and the bottom surface 26a becomes the rolling surface of the needle roller 40 is formed in the circumferential direction. In order to smoothly move the needle rollers 40 in the radial base end side of the concave groove portion 26, that is, at the root portion of the leg shaft 24, the concave groove portion 26 is recessed so as to recede from the bottom surface 26a of the concave groove portion 26. A relief portion (relief) 29 is formed.

  Moreover, the outer side collar part 21 is provided in the radial direction front-end | tip of the concave groove part 26 via the circumferential groove | channel along the leg-axis circumferential direction. This circumferential groove 31 also forms a dull portion (relief) 31.

  By the way, the leg shaft 24 is formed by turning the concave groove portion 26 (range A in FIG. 3) and the thinning portions (relief) 29 and 31 (ranges B and B in FIG. 3), and thereafter the range A and the range. B was subjected to carburizing heat treatment for carburizing, quenching and tempering, followed by quenching steel cutting.

  Here, the carburizing heat treatment is a process in which carbon is impregnated from the surface layer (carburizing treatment) by heating the steel for a long time in a carburizing agent such as a gas, liquid or solid containing a large amount of carbon. It is a method of quenching and tempering steel. Also, hardened steel cutting is simply cutting, and since cutting is usually performed in the state of raw material, it was called hardened steel cutting in order to clarify that the cutting was after heat treatment (after quenching). . In this way, by applying hardened steel cutting, compressive residual stress is applied to the surfaces of the thinning portions 29 and 31, and a compressive residual stress processing portion is formed. The stress that remains in the material after the external force is removed and is in a compressed state is called compressive residual stress. In general, materials are often damaged by tensile stress, and if there is compressive residual stress, fatigue strength improves.

  In hardened steel cutting, part of the chips to be removed during cutting is pushed into the surface and stretched onto the surface. Further, mechanical factors due to shear deformation and thermal factors due to cutting heat generated when the structure undergoes shear deformation remain superimposed. For this reason, compressive residual stress is generated by performing quenching steel cutting.

  Since the trunnion of the tripod type constant velocity universal joint according to the present invention is provided with the thinning portion 29 which is recessed at the base portion of the leg shaft 24 so as to recede from the rolling surface 26a of the needle roller 40, this thinning portion. 29, the needle rollers 40 can move in the radial direction. For this reason, a stable operating angle can be taken and a smooth operation is possible. In addition, since the surface of the thinning portion 29 is a compressive residual stress processing portion, the leg shaft 24 is excellent in strength and excellent in durability.

  As described above, the compressive residual stress processing portion can be formed by shot peening without depending on hardened steel cutting. Shot peening is a process of projecting small particles onto the surface of the object to be processed, and is performed under the condition that the outermost surface is plastically deformed for the purpose of generating a compressive residual stress on the surface. For this reason, a compression residual stress processing part can be shape | molded also by such shot peening.

  Thus, the compressive residual stress processing part of the thinning part 29 can be shape | molded by hardening steel cutting, shot peening, etc., and can perform the stable compressive residual stress processing. In particular, in hardened steel cutting, if the hardened steel cutting, which is a dry process, is performed in the finishing process, a grinding fluid is unnecessary, and there is an advantage that the burden on the environment is reduced.

  If the outer collar 21 is provided on the radial front end side of the rolling surface 26 a of the leg shaft 24, the outer collar 21 restricts the needle rollers 40 from coming off in the radial distal direction. Therefore, during the operation of the constant velocity universal joint, the trunnion unit (the unit body in which the trunnion 10, the needle roller 40, and the roller 30 are assembled) is not disassembled in the outer ring 10, and a stable operation is achieved. Make it possible.

  In addition to the carburizing heat treatment, the heat treatment may be an induction heat treatment. Here, high-frequency heat treatment is a hardening method that applies the principle of heating a conductive object by placing Joule heat in a coil through which high-frequency current flows, and generating Joule heat by electromagnetic induction. is there.

  By the way, when carburizing heat treatment or induction heat treatment is performed, it may be performed on the entire surface of the trunnion 20. Thus, by performing heat treatment on the entire surface, the strength is excellent and a stable function is exhibited over a long period of time. Further, by applying hardened steel cutting or grinding to the rolling surface 26a of the leg shaft 24, the needle rollers 40 roll on the rolling surface 26a more smoothly. Here, the entire surface means the outer peripheral surface (outer diameter surface) of the boss portion 22, the ranges A and B of the leg shaft 24 in FIG. These are the inner surface of the boss portion 22 and the surface.

  As described above, the embodiment of the present invention has been described. However, the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, the outer shaft 21 is provided on the leg shaft 24. Thus, the roller 40 is prevented from coming off in the outer diameter direction, but such an outer flange 21 may not be provided. In this case, a washer member may be attached to the distal end portion of the leg shaft 24 instead of the outer flange portion 21.

  In the roller rolling surface (range A shown in FIG. 3) formed by the bottom surface 26a of the concave groove portion 26, the hardened steel cutting is performed in the above embodiment, but grinding is performed instead of such hardened steel cutting. You may make it perform. Thus, by grinding, a roller can roll more smoothly and efficient rotation transmission can be performed. However, it is advantageous from the viewpoint of cost that the range A and the ranges B and B in FIG. 3 are hardened steel cutting which is the same processing method. Further, as the hardened layer to be formed, it is possible to omit the inner diameter surface of the boss portion 22, the tip surface of the leg shaft 24, and the like.

  Two samples were prepared for each of the product of the present invention and the comparative product, and the strength of each sample was confirmed by a uniaxial torsional fatigue test. The single swing torsional fatigue test is a test in which a predetermined torque is repeatedly applied. That is, in evaluating the strength of the trunnion, there are mainly static torsional strength (test) and swing fatigue strength (test). Usually, in both tests, the shaft is set so as to be damaged first. Therefore, the tripod member (trunnion) or the roller is set to have a strength higher than that of the shaft. Here, the static torsion strength is evaluated by a torque at which any part is twisted in a static torsion test in which torque is applied to the tripod type constant velocity universal joint. The cantilever fatigue strength is evaluated based on the number of repetitions until a certain portion of the tripod type constant velocity universal joint is loaded with a predetermined swing torque and torsion is cut off.

  The product of the present invention is obtained by performing carburizing heat treatment such as carburizing and quenching and tempering, and then performing quenching steel cutting after turning the ranges A and B shown in FIG. The comparative product is obtained by performing a carburizing and tempering carburizing heat treatment after performing a turning process on the range A shown in FIG. 3 and then performing a grinding process. After turning, carburizing heat treatment for carburizing and tempering was performed.

  In this case, the residual compressive stress of the thin portion 29 of the leg shaft root portion in the product of the present invention was 500 MPa to 600 MPa, and the residual compressive stress in the comparative product was 100 MPa to 200 MPa.

  The number of loads until breakage was 26,000 times and 35,000 times for the comparative product, while 160000 times and 200000 times for the product of the present invention. From this result, it can be seen that the residual compressive stress processing portion provided in the base portion 29 of the leg shaft root portion has higher strength than that provided with no residual compressive stress processing portion (5 times higher). I was able to achieve strength).

21 Outer flange portion 22 Boss portion 24 Leg shaft 26a Bottom surface (rolling surface)
29, 31 Dull section 30 Roller 40 Needle roller

Claims (10)

It has a boss part and three leg shafts projecting radially from the circumferentially equal position of the boss part, and a rolling surface on which a plurality of needle rollers rolls on the outer peripheral surface of each leg shaft A trunnion of formed tripod type constant velocity universal joint,
A tripod type characterized in that a base portion of the leg shaft is provided with a relief portion that is recessed so as to recede from the rolling surface of the needle roller, and the surface of the relief portion is a compression residual stress treatment portion. Trunnion of constant velocity universal joint.   The trunnion of the tripod type constant velocity universal joint according to claim 1, wherein the compressive residual stress processing section is formed by cutting hardened steel after heat treatment.   The trunnion of a tripod type constant velocity universal joint according to claim 1, wherein the compressive residual stress processing section is configured by shot peening after heat treatment.   The trunnion of a tripod type constant velocity universal joint according to claim 1, wherein the compressive residual stress processing section is formed by quenching steel cutting and shot peening after heat treatment.   The trunnion of the tripod type constant velocity universal joint according to any one of claims 1 to 4, wherein an outer flange is provided on a radially leading end side of the rolling surface of the leg shaft.   The trunnion of the tripod type constant velocity universal joint according to any one of claims 1 to 5, wherein the entire surface is subjected to a carburizing heat treatment.   The trunnion of a tripod type constant velocity universal joint according to any one of claims 1 to 5, wherein the entire surface is subjected to induction heat treatment.   The trunnion of the tripod type constant velocity universal joint according to claim 6 or 7, wherein the rolling surface of the leg shaft is subjected to hardened steel cutting.   The trunnion of the tripod type constant velocity universal joint according to claim 6 or 7, wherein a rolling surface of the leg shaft is ground.   The tripod type constant velocity universal joint using the trunnion of the tripod type constant velocity universal joint of any one of the said Claims 1-9.

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