Tri-lobe type constant velocity universal joint

Abstract

Provided is a three-ball-pin type constant-velocity universal joint of a double-row roller type. For the outer peripheral surface of a foot shaft, a convex curve bulging to both sides in a torque transmission direction is provided in a longitudinal cross section and a transverse cross section, and the curvature center of the convex curve in the longitudinal cross section is offset to the side opposite the convex curve, the curvature center of the convex curve in the transverse cross section is offset to the side of the convex curve, when the radius of curvature of the convex curve in the longitudinal cross section is set as r, and the radius of curvature of the convex curve in the transverse cross section is set as R, r > R is provided, and the transverse cross-sectional shape of the foot shaft is an oblong shape. A three-ball-pin member is composed of a main body and a foot shaft, the foot shaft projects in the joint radial direction via a foot shaft neck portion that is smaller than the foot shaft, the transverse cross-sectional shape of the foot shaft neck portion is an oblong shape, and a radial difference is provided between the outer peripheral portion of the foot shaft neck portion and the outer peripheral portion of the foot shaft.

Description

Technical Field

[0001] This invention relates to a three-ball pin type constant velocity universal coupling. Background Technology

[0002] In the drive shafts used in the power transmission systems of motor vehicles, it is common to install a sliding constant velocity universal joint on the inner side (the center side in the vehicle width direction) and a fixed constant velocity universal joint on the outer side (the outer side in the vehicle width direction). The sliding constant velocity universal joint allows both angular displacement and axial relative movement between the two shafts, while the fixed constant velocity universal joint allows angular displacement between the two shafts but not axial relative movement.

[0003] As a sliding constant velocity universal joint, the three-ball pin type constant velocity universal joint is well known. This three-ball pin type constant velocity universal joint includes single-row roller type and double-row roller type. The single-row roller type three-ball pin type constant velocity universal joint is formed by rotatably mounting rollers inserted into the raceway grooves of the outer coupling member to the axle of the three-ball pin member via multiple needle rollers. The double-row roller type three-ball pin type constant velocity universal joint... Figure 16 and Figure 17 As shown, the roller 111 is provided in the raceway groove 105 of the outer coupling member 102, and the foot axle 132 is externally fitted into the three ball pin member 103, so that the roller 111 is supported as a freely rotatable inner ring 112 (see, for example, Patent Document 1).

[0004] In double-row roller type three-ball pin type constant velocity universal couplings, such as Figure 18 As shown, the cross-section of the foot axle 132 (the section orthogonal to the axis of the foot axle) is set to an elliptical shape, and as... Figure 16 As shown, the inner circumferential surface of the inner ring 112 is designed with a convex circular arc shape in cross-section. Thus, as... Figure 19 As shown, the roller 111 can swing relative to the foot axle 132, thus, compared to a single-row roller type, it has the advantages of reducing induced thrust (axial force induced by friction between components inside the coupling) and sliding resistance. Furthermore, as... Figure 18 As shown, the cross-sectional shape of the foot shaft 132 is elliptical, but in this case, its major axis a is arranged parallel to the torque load direction, and its minor axis b is arranged in a direction orthogonal to the torque load direction.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2000-320563 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] In the aforementioned three-ball pin type constant velocity universal coupling, such as Figure 17 As shown, the outer peripheral surface 115 of the roller 111 is a convex curved surface with an arc-shaped generatrix, and the roller guide surface 106 in contact with it has a concave cross-sectional shape (Gothic arch shape) that mimics the shape of the outer peripheral surface 115 of the roller 111, and they are in angular contact. Therefore, structurally, when the constant velocity universal coupling rotates in the state of obtaining the working angle, it produces a... Figure 20 The phenomenon shown, where the roller unit 104, including roller 111 and inner ring 112, tilts in the direction of arrow B on a section orthogonal to the coupling axis (hereinafter referred to as "left-right tilt"), is as follows: Figure 21 The roller unit 104 shown exhibits a tilting phenomenon along the direction of arrow C in a section parallel to the coupling axis (hereinafter referred to as "forward and backward tilting"). If left-right tilting and forward and backward tilting occur in the roller unit 104, the rolling resistance at the contact portion between the roller 111 and the roller guide surface 106, and the rotational resistance to the foot shaft 32 of the roller unit 104, increase. Furthermore, the needle rollers 117 within the roller unit 104 can no longer roll relative to the roller guide surface 106 in the axial direction of the outer coupling member 102, thus increasing the sliding resistance. When these factors are significant, the induced thrust and sliding resistance increase, leading to a deterioration in the NVH (Noise, Vibration, Harshness) characteristics of the constant velocity universal coupling.

[0010] Furthermore, in the aforementioned three-ball pin type constant velocity universal coupling, the cross-section of the foot axle 132 is elliptical, and the cross-section of the inner circumferential surface of the inner ring 112 is convex circular arc. Therefore, the contact between the inner ring 112 and the foot axle 132 is approximately point contact, which can suppress the frictional torque that causes the roller unit 104 to tilt with the movement of the foot axle 132. Additionally, even when the coupling is at an angle, the foot axle 132 contacts the center of the inner ring 112 in the width direction (axial direction of the foot axle 132), thus creating a structure that suppresses lateral tilting. However, when the coupling is at a large angle, because the cross-section of the foot axle 132 is elliptical, the roller unit 104 generates a forward / backward tilting (see reference). Figure 21 The force generated. In addition, since the contact area between the foot axle 132 and the inner ring 112 is small, the surface pressure of the contact surface between the two increases under high torque loads such as those under extremely strict vehicle operating conditions, which may affect the durability of the foot axle 132.

[0011] Therefore, the present invention can ensure high strength of the neck and, as a three-ball pin type constant velocity universal coupling, can provide a three-ball pin type constant velocity universal coupling that can achieve high working angle and improve the grindability of the foot shaft.

[0012] Methods for solving problems

[0013] The three-ball-pin type constant velocity universal joint of the present invention comprises: an outer coupling member having three raceway grooves extending axially along the coupling on its inner circumferential surface, and a pair of roller guide surfaces facing each other in the circumferential direction of the coupling provided in each raceway groove; a three-ball-pin member disposed on the inner circumference of the outer coupling member and having three foot shafts protruding toward the raceway grooves in the radial direction of the coupling; and three roller units comprising an inner ring disposed on the outer circumference of the foot shafts and supported by the foot shafts in a rotatable and swingable state, rollers disposed in the raceway grooves and on the outer diameter side of the inner ring, and a plurality of rolling elements disposed between the inner ring and the rollers and between the inner ring and the outer ring. In the three-ball-pin type constant velocity universal joint, for the outer circumferential surface of the foot shafts, in the longitudinal section and cross section... The three-ball pin component has a convex curve bulging outwards in both directions of torque transmission. The center of curvature of the convex curve in the longitudinal section is offset from the side opposite to the center axis of the foot axle. The center of curvature of the convex surface in the cross section is offset from the side of the convex curve relative to the center axis of the foot axle and from the rotation direction of the three-ball pin component. When the radius of curvature of the convex curve in the longitudinal section is set as r and the radius of curvature of the convex surface in the cross section is set as R, r > R, so the cross-sectional shape of the foot axle is set as an elongated oval shape. The three-ball pin component has a main body and the foot axle protruding in the radial direction of the coupling via a foot axle neck that is smaller than the foot axle. The cross-sectional shape of the foot axle neck is set as an elongated oval shape. A radial difference is provided between the arc-shaped portion of the outer periphery of the foot axle neck and the arc-shaped portion of the outer periphery of the foot axle.

[0014] According to the three-ball pin type constant velocity universal coupling of the present invention, the neck of the three-ball pin member has an elongated oval shape with a larger wall thickness on the torque load side in cross-sectional shape, which allows the wall thickness of the neck to be thicker relative to the torque load direction of the three-ball pin member. In addition, conversely, it allows the dimension (width dimension) in the direction orthogonal to the torque load direction to be smaller, which can avoid interference between the neck and the inner diameter of the roller box (i.e., the inner diameter of the inner ring) at high operating angles.

[0015] However, in this type of three-ball pin constant velocity universal coupling, the three-ball pin component typically consists of a main body and a foot pin. The foot pin protrudes radially from the coupling via a foot pin journal, which is smaller than the foot pin itself. The foot pin journal has a circular cross-section and a cylindrical outer surface. In this case, if the neck diameter is large and the coupling achieves a high working angle, interference will occur between the neck and the inner diameter of the roller box. Therefore, this hinders achieving a high working angle. That is, to achieve a high working angle, the diameter of the neck needs to be reduced. However, if the neck diameter is reduced to a smaller size, the strength may decrease.

[0016] Furthermore, if the cross-sectional shape of the axle is oblong and the cross-sectional shape of the ankle is circular, the radial difference between their outer circumferences decreases on the shorter axis side of the axle. This makes it difficult to perform finishing work on areas where the radial difference is smaller. Typically, the ankle is forged, while the axle is ground. Therefore, during the grinding of the axle, the grinding wheel, cutting tools, etc., interfere with the ankle, which is not preferable in manufacturing.

[0017] In contrast, in the three-ball pin type constant velocity universal coupling of the present invention, a radial difference is provided between the outer periphery of the journal of the foot shaft and the outer periphery of the foot shaft. Therefore, there is no part where the radial difference becomes smaller, which can effectively prevent interference between the grinding wheel, cutting tool, etc. and the journal during the grinding of the foot shaft.

[0018] The convex curve in the cross-section of the outer peripheral surface of the axle has a shape that separates more from the cylindrical inner peripheral surface of the inner ring as it approaches the axial sides of the coupling from the end in the torque transmission direction. As a result, the circumferential length (i.e., the major axis of the contact ellipse) of the contact portion between the outer peripheral surface of the axle and the inner peripheral surface of the inner ring in the cross-section becomes shorter, thus reducing the force (torque) required to tilt the rollers. However, in this case, the contact area between the axle and the inner ring becomes smaller, raising concerns about the surface pressure at their contact points increasing. Therefore, in this invention, as described above, the radius of curvature (r) of the convex curve in the longitudinal section of the outer peripheral surface of the axle is set larger than the radius of curvature (R) of the convex curve in the cross-section of the outer peripheral surface of the axle. This increases the axial length (i.e., the minor axis of the contact ellipse) of the contact portion between the outer peripheral surface of the axle and the inner peripheral surface of the inner ring, thus suppressing the increase in surface pressure at their contact points.

[0019] Preferably, the inner circumference of the inner ring is a flat cylindrical surface. On the outer circumferential surface of the axle, a convex curve bulging towards the inner circumferential surface of the inner ring is provided in both the longitudinal and cross-sectional sections. Furthermore, the convex curve of the cross-section of the outer circumferential surface of the axle has a shape that separates more from the cylindrical inner circumferential surface of the inner ring as it approaches the axial sides of the coupling from the end in the torque transmission direction. As a result, the circumferential length of the axle at the contact portion between the outer circumferential surface of the axle and the inner circumferential surface of the inner ring in the cross-section becomes shorter (i.e., the major axis of the contact ellipse), thus reducing the force (torque) required to tilt the roller.

[0020] Preferably, the outer peripheral surface of the roller has a cylindrical shape, and the roller guide surface has a flat surface. With this configuration, under torque load, the flat roller guide surface and the cylindrical outer peripheral surface of the roller press against each other through a straight contact portion, thereby suppressing the lateral tilting of the roller.

[0021] Preferably, when the center of curvature of the convex portion of the cross-sectional shape of the foot shaft journal coincides with the center of curvature of the end arc portion of the cross-sectional shape of the foot shaft, and the radius of curvature of the end arc portion of the cross-sectional shape of the foot shaft journal is set to R´ and the radius of curvature of the convex portion of the cross-sectional shape of the foot shaft is set to R, R´ < R. It is particularly preferred that R´ / R be set to 0.80 to 0.95. With this setting, the grinding machinability is stable, and the strength of the foot shaft is also stable.

[0022] Preferably, when the neck width dimension in the minor axis direction of the cross-sectional shape of the foot journal is set to W´, and the inter-arc dimension of the cross-sectional shape of the foot journal, i.e., the foot journal diameter, is set to D, W´ / D is set to 0.70 to 0.90. By setting it in this way, it is possible to ensure that the neck does not interfere with the inner ring even when the maximum working angle is achieved.

[0023] When the width dimension of the cross-sectional shape of the foot axle in the minor axis direction is set as W, and the width dimension of the cross-sectional shape of the foot axle neck in the minor axis direction is set as W´, it can also be set as W´=W. In this way, even if the part of the foot axle with the same size as the neck is ground, it will not have an adverse effect on the neck. In addition, the part with radial difference will not form a part with a smaller radial difference, which can effectively prevent interference from grinding wheels, cutting tools, etc. during the grinding of the foot axle.

[0024] The short axis side of the cross-sectional shape of the foot shaft journal can also be straight or a slightly curved arc. Even if it is straight or a slightly curved arc, a radial difference is provided between the outer periphery of the foot shaft journal and the outer periphery of the foot shaft, which can effectively prevent interference between the grinding wheel, cutting tool, etc. and the neck during the grinding of the foot shaft.

[0025] Invention Effects

[0026] This invention allows for a thicker neck wall relative to the torque load direction of the three-ball pin component, thus ensuring high neck strength. Furthermore, it avoids interference between the neck and the inner diameter of the inner ring at high working angles, enabling a high working angle for a three-ball pin type constant velocity universal coupling. It effectively prevents interference between the grinding wheel, cutting tools, etc., and the neck during grinding of the axle, improving the grindability of the axle. Attached Figure Description

[0027] Figure 1 This is a cross-sectional view of the coupling axially of the three-ball pin type constant velocity universal coupling involved in this invention.

[0028] Figure 2 yes Figure 1 The KK line cross-sectional view in the image.

[0029] Figure 3 This is a longitudinal sectional view of the roller box.

[0030] Figure 4 This is a cross-sectional view of the roller box.

[0031] Figure 5 This is a side view showing a partial cross-section of the three-ball pin component.

[0032] Figure 6 This is a front view showing a partial cross-section of the three-ball pin component.

[0033] Figure 7 yes Figure 6 A cross-sectional view of the neck of the three-ball pin component shown.

[0034] Figure 8 This is a diagram showing the relationship between the radial difference between the foot axle and the foot axle neck.

[0035] Figure 9 This is a side view showing a partial cross-section of another three-ball pin component.

[0036] Figure 10 This is the front view of another three-ball pin component.

[0037] Figure 11 It is shown Figure 10 The diagram shows the relationship between the radial difference between the foot axle and the foot axle neck of the three-ball pin component.

[0038] Figure 12A It is a cross-sectional view showing the neck and the elongated oval shape formed by a pair of parallel straight sections and a pair of arcuate sections provided at the ends of the parallel straight sections.

[0039] Figure 12B It is a cross-sectional view showing the neck and the elongated oval shape formed by a pair of flat arcuate portions and a pair of arcuate portions at the ends of the flat arcuate portions.

[0040] Figure 13 It is a cross-sectional view of the neck, which has a circular cross-section.

[0041] Figure 14 It shows the use of having Figure 13 A cross-sectional view of the undesirable condition of the three ball pin components in the neck shown.

[0042] Figure 15 This is a simplified diagram illustrating the change in the radial difference between the foot pivot and the foot pivot neck.

[0043] Figure 16 This is a cross-sectional view of the axial direction of the coupling in the traditional three-ball pin type constant velocity universal coupling.

[0044] Figure 17 yes Figure 16A partial cross-sectional view at the KK line.

[0045] Figure 18 yes Figure 16 A sectional view at line LL.

[0046] Figure 19 It means Figure 16 A cross-sectional view of the working angle of a three-ball pin type constant velocity universal joint.

[0047] Figure 20 Is with Figure 16 A cross-sectional view of the three-ball pin type constant velocity universal joint, showing the axial orthogonal joint, indicating the left and right tilting state that produces the roller unit.

[0048] Figure 21 yes Figure 16 A cross-sectional view of the axial direction of the three-ball pin type constant velocity universal joint shows the state in which the roller unit is tilted forward and backward. Detailed Implementation

[0049] The following is based on Figures 1 to 8 The embodiments of the present invention will be described. Figures 1-4 The diagram shows a three-ball pin type constant velocity universal coupling 1 according to the present invention. This three-ball pin type constant velocity universal coupling 1 is a double-row roller type. It should be noted that, in the following description, the axial direction of the three-ball pin type constant velocity universal coupling when the working angle is set to 0° is referred to as the "coupling axial direction", and the circumferential direction and radial direction centered on this axial direction are referred to as the "coupling circumferential direction" and "coupling radial direction", respectively.

[0050] like Figure 1 and Figure 2 As shown, the three-ball pin type constant velocity universal joint 1 includes an outer coupling member 2, a three-ball pin member 3 serving as an inner coupling member, and a roller unit 4 serving as a torque transmission member.

[0051] The outer coupling component 2 is cup-shaped, with one end open and the other end closed in the axial direction of the coupling (see reference). Figure 1 Three straight raceway grooves 5 extending axially along the coupling are formed at equal intervals on the inner circumferential surface of the outer coupling member 2 in the circumferential direction of the coupling (see reference). Figure 2 Each raceway groove 5 has a pair of roller guide surfaces 6 arranged opposite each other in the circumferential direction of the coupling. Each roller guide surface 6 extends axially upward in the coupling. The outer coupling member 2 houses a three-ball pin member 3 and a roller unit 4.

[0052] The three-ball pin assembly 3 integrally comprises: a main body 31 (trunnion main body) having a central hole 30; and three foot shafts 32 (trunnion journals) protruding radially from a third of the coupling circumferential position on the outer peripheral surface of the main body 31. In this case, the foot shafts 32 protrude radially from the main body 31 via small foot shaft journals (necks) 29. By fitting the external spline formed on the shaft 8 into the internal spline formed in the central hole 30 of the main body 31 and fixing them axially to the coupling using retaining rings or the like, the three-ball pin assembly 3 and the shaft 8 are combined in a manner capable of torque transmission.

[0053] Roller units 4 are disposed on the outer periphery of each foot shaft 32 of the three ball pin component 3, and as shown in the figure. Figure 3 and Figure 4 As shown, the rollers are respectively housed in the raceway grooves 5 of the outer coupling member 2. The roller unit 4 includes an annular roller, i.e., an outer ring 11, centered on the axis of the foot shaft 32; an annular inner ring 12 disposed on the inner circumference of the outer ring 11 and externally fitted into the foot shaft 32; and rolling elements 13 sandwiched between the outer ring 11 and the inner ring 12. In this embodiment, as an example of the rolling elements 13, a plurality of needle rollers 13 in a full-load roller state without retainers are used. The needle rollers 13 use the cylindrical inner circumferential surface of the outer ring 11 as the outer track surface and the cylindrical outer circumferential surface of the inner ring 12 as the inner track surface, and are arranged to roll freely between the outer track surface and the inner track surface. The roller unit 4, composed of the outer ring 11, the inner ring 12, and the needle rollers 13, is constructed so as not to disintegrate naturally by means of a pair of retaining rings 14.

[0054] Next, the relationship between the roller guide surface 6 and the outer ring 11 will be explained. In this case, the coupling axial direction is taken as the Z direction, the axis of the foot shaft 32 is taken as the Y direction, and the torque transmission direction orthogonal to both the coupling axial direction Z and the foot shaft axis direction Y is taken as the X direction.

[0055] The outer circumferential surface 15 of the outer ring 11 is a cylindrical surface centered on the axis of the foot axle 32. The end faces 16 on both sides of the outer ring 11 along its own axial direction are considered as flat surfaces orthogonal to its own axis (see reference). Figure 3 The outer peripheral surface 15 and the two end surfaces 16 of the outer ring 11 are connected by a chamfer 17. The chamfer 17 is formed, for example, by a tapered surface with a straight cross section and a convex surface with a curved cross section (e.g., an arc) that smoothly connects the tapered surface to the outer peripheral surface 15 and the two end surfaces 16.

[0056] The pair of roller guide surfaces 6 of each raceway groove 5 of the outer coupling component 2 are parallel flat surfaces. A pair of guide surfaces 7 are provided on both sides of each roller guide surface 6 in the width direction (Y direction). The guide surfaces 7 rise from both ends of the roller guide surface 6 in the width direction towards the axis Y of the foot shaft 32. The shapes of the roller guide surfaces 6 and 7 mimic the shapes of the outer peripheral surface 15 and chamfer 17 of the outer ring 11. Specifically, the roller guide surfaces 6 are parallel to the outer peripheral surface 15 of the outer ring 11, and the spacing between the opposing pair of roller guide surfaces 6 is slightly larger than the diameter of the outer peripheral surface 15 of the outer ring 11. This creates a small gap in the X direction between the roller guide surfaces 6 and the outer peripheral surface 15 of the outer ring 11. Furthermore, the guide surfaces 7 are approximately parallel to the chamfer 17 of the outer ring 11, and for example, are composed of a straight-section inclined surface and a curved (e.g., arc-shaped) concave surface that smoothly connects the inclined surface to the roller guide surfaces 6. The distance between the pair of guide surfaces 7 arranged on both sides of the roller guide surface 6 in the width direction is slightly larger than the distance between the pair of chamfers 17 arranged on both sides of the outer peripheral surface 15 of the outer ring 11 in the width direction. As a result, a small gap in the Y direction is formed between the guide surfaces 7 and the chamfers 17 of the outer ring 11.

[0057] When a torque in the direction of arrow T is applied to the outer coupling member 2, the outer peripheral surface 15 of the outer ring 11 is pressed against the roller guide surface 6 on the left side of the figure. In this embodiment, as described above, the roller guide surface 6 is a flat surface, and the outer peripheral surface 15 of the outer ring 11 is a cylindrical surface; therefore, they press against each other via a straight contact portion. As a result, the posture of the outer ring 11 is corrected so that the outer peripheral surface 15 of the outer ring 11 is parallel to the roller guide surface 6, thus suppressing the lateral tilt of the outer ring 11 (see reference). Figure 13 Additionally, the guide surface 7 abuts against the chamfer 17 of the outer ring 11 from the Y direction, thereby causing the outer ring 11 to tilt forward and backward (as in the past). Figure 21 The tilt of the arrow in the direction of C is restricted, and the left and right tilt of the outer ring 11 is further suppressed.

[0058] When the outer coupling component 2 is applied as described above Figure 3 When the torque is applied in the direction of arrow T, the outer peripheral surface 15 of the outer ring 11 is pressed against the roller guide surface 6 on the left side of the figure (hereinafter referred to as "the roller guide surface 6 on the torque load side"). On the other hand, a gap is formed between the roller guide surface 6 on the right side of the figure (hereinafter referred to as "the roller guide surface 6 on the torque non-load side") and the guide surfaces 7 on both sides of its width direction, the outer peripheral surface 15 of the outer ring 11, and the chamfer 17. At this time, the roller unit 4 is tilted, and when the outer peripheral surface 15 and the chamfer 17 of the outer ring 11 contact the roller guide surface 6 and the guide surface 7 on the torque non-load side, the rotational resistance of the outer ring 11 increases.

[0059] Therefore, in this embodiment, the initial gap between the outer ring 11 and the roller guide surface 6, the shape of the guide surface 7, etc., are designed such that when a torque is applied to the three-ball pin member 3, the outer ring 11 contacts the roller guide surface 6 on the torque load side, while not contacting the roller guide surface 6 on the torque non-load side and the guide surfaces 7 on both sides in the width direction.

[0060] Next, use Figure 3 and Figure 4 The shapes of the inner circumferential surface 18 of the inner ring 12 and the outer circumferential surface 33 of the foot axle 32 are described in detail. The inner circumferential surface 18 of the inner ring 12 is a cylindrical surface parallel to the Y-axis direction of the foot axle.

[0061] In a longitudinal section including the axis of the foot axle 32 itself, the outer peripheral surface 33 of the foot axle 32 has convex curves bulging outwards towards both sides in the torque transmission direction X. In the example shown, the convex curves in the longitudinal section of the outer peripheral surface of the foot axle 32 are formed by arcs 33a with a radius of curvature r. Thus, the top (X-direction end) of the arcs 33a on the outer peripheral surface of the foot axle 32 is nearly opposite to the cylindrical inner peripheral surface 18 of the inner ring 12, and the gap between the outer peripheral surface 33 of the foot axle 32 and the inner peripheral surface 18 of the inner ring 12 gradually increases as the top of the arcs 33a approaches both sides in the Y-direction. In this case, the curvature centers Oa of the arcs 33a of the convex curve in the longitudinal section are offset by a dimension E to the side opposite to the convex curve.

[0062] In Figure 4 In the cross-section shown, orthogonal to the axis of the foot axle 32, the outer peripheral surface of the foot axle 32 has convex curves bulging outwards in both directions of the torque transmission direction X. In the example shown, the convex curves in the cross-section of the outer peripheral surface of the foot axle 32 are formed by arcs 33b with a radius of curvature R. In this case, the curvature centers Ob and Ob of the arcs 33b of the convex curve in the cross-section are offset by a dimension F towards the convex curve side.

[0063] The arc 33b of the outer peripheral surface of the foot axle 32 is nearly opposite to the cylindrical inner peripheral surface 18 of the inner ring 12 at its top (X direction end). As it gets closer to the Z direction sides from the top, it separates from the inner peripheral surface 18 of the inner ring 12, thus creating a gap G between them in the Z direction.

[0064] As described above, the outer peripheral surface 33 of the foot axle 32 has an aspherical shape with a radius of curvature r of the convex curve (circular arc 33a) in the longitudinal section and a radius of curvature R of the convex curve (33b) in the cross section. In addition, the radius of curvature r is set to be larger than the radius of curvature R, that is, r is set to be greater than R. However, in this case, the radius of curvature r is set to be larger than half of the maximum dimension of the torque transmission direction of the foot axle 32 (the maximum diameter of the foot axle 32 when the working angle is 0°, as described later). In addition, the radius of curvature R is smaller than half of the maximum diameter of the foot axle 32.

[0065] However, for the foot neck 29, if its cross-sectional shape is Figure 13 A circular shape like the one shown requires a larger diameter for the neck 29 to increase its strength. However, if the diameter of the neck 29 is larger, then when obtaining the working angle, such as Figure 14 As shown, the neck 29 will interfere with the inner diameter end of the inner ring 12 of the roller box (roller unit) 4. Therefore, the working angle θ cannot be too large. To obtain a large working angle (e.g., 20° to 28°) as a sliding constant velocity universal coupling, the neck 29 with a cross-sectional shape needs to be set as a minor diameter. If it is set as a minor diameter, the strength will be deteriorated.

[0066] Furthermore, the cross-sectional shape of the foot axle 32 involved in this invention is an elongated oval formed by a pair of parallel straight sections 33c and 33d and arcs 33b provided at both ends of the straight sections. Therefore, if the cross-sectional shape of the foot axle neck 29 is Figure 13 A circle like the one shown, then in... Figure 15 When comparing the cross-sectional shapes of the foot neck 29 and the foot shaft 32 as shown, such as... Figure 15 As shown, the radial difference between the outer circumferential surface of the foot pivot 32 and the outer circumferential surface of the foot pivot neck 29 is uneven over the entire circumference. That is, the radial difference decreases as it approaches the straight portion of the foot pivot 32 from the portion corresponding to the arc 33b. For example, when the radial difference of the portion corresponding to the arc 33b of the foot pivot 32 is set as A1 and the radial difference near the foot pivot 32 is set as B1, A1 > B1.

[0067] However, in this type of three-ball pin component, the neck 29 is typically forged, while the foot 32 is ground. Therefore, as... Figure 15 As shown, the radial difference between the outer peripheral surface of the foot axle 32 and the outer peripheral surface of the foot axle neck 29 is uneven. If the radial difference decreases (shrinks), interference from the grinding wheel, grinding tools, etc., on the neck 29 will occur during grinding, reducing machining accuracy. It should be noted that, for the three-ball pin type constant velocity universal coupling involved in this invention, in the foot 32, as... Figure 7 As shown, arc 33b is designated as the grinding range, while the side edges 33c and 33d on the short shaft end are designated as the non-grinding range. Therefore, the radial difference within the grinding range is uneven.

[0068] Therefore, in this invention, as Figure 4 , Figure 7 As shown, the cross-sectional shape of the neck 29 is set to be an elongated oval, similar in shape to the elongated oval of the foot axle. That is, the cross-sectional shape of the neck 29 is also set to be an elongated oval formed by a pair of parallel straight sections 29c, 29d and arcs 29b, 29b provided at both ends of these straight sections, as shown. Figure 8As shown, the radial difference between the two arc-shaped portions is uniform. Furthermore, the major axis of the elongated circle in the cross-section of the neck 29 is parallel to the load direction. Figure 8 It shows Figure 6 The cross-sectional shape of the PP section shown, i.e. the minimum diameter part of the neck 29, is referred to as the "end arc portion".

[0069] In this case, the center of curvature Ob of the arc 33b of the cross-section of the foot axle 32 coincides with the center of curvature Ob1 of the arc 29b of the cross-section of the neck 29. When the radius of curvature of the arc 33b of the cross-section of the foot axle 32 is set as R and the radius of curvature of the arc 29b of the cross-section of the neck 29 is set as R´, then R > R´. In addition, when the length of the minor axis direction (foot axle width dimension) of the cross-section of the foot axle 32 is set as W and the length of the minor axis direction direction (neck width dimension) of the cross-section of the neck 29 is set as W´, then W > W´. As a result, the radial difference RR´ between the two arc-shaped portions is uniform.

[0070] Specifically, when R´ / R is set to 0.80~0.95, the minor axis direction of the cross-sectional shape of the foot axle neck 32, i.e., the neck width dimension, is set to W´, and the arc part dimension of the cross-sectional shape of the foot axle, i.e., the foot axle diameter, is set to D, W´ / D is set to 0.70~0.90.

[0071] According to the three-ball pin type constant velocity universal joint of the present invention, the neck 32 of the three-ball pin member 3 has an elongated oval shape with a large wall thickness on the torque load side in its cross-sectional shape, which allows the wall thickness of the neck 29 to be thicker relative to the torque load direction of the three-ball pin member 3. This ensures high strength of the neck 29. Furthermore, conversely, the dimension (width dimension) in the direction orthogonal to the torque load direction can be smaller, avoiding interference between the neck 29 and the inner diameter of the roller box 4 (i.e., the inner diameter of the inner ring 12) at high operating angles. Therefore, a high operating angle can be achieved as a three-ball pin type constant velocity universal joint.

[0072] That is, a radial difference is provided between the outer periphery of the journal 29 and the outer periphery of the journal 32, and this radial difference is set to be constant. Therefore, no area where the radial difference decreases is created, effectively preventing interference between the grinding wheel, cutting tool, etc., and the journal 29 during grinding of the journal 32. This "constant" range is a range that can be machined using conventional machining methods such as turning and grinding. As a reference, it is set to be within ±10% of this radial difference. More preferably, it is set to be within ±5% of this radial difference.

[0073] Preferably, the inner circumferential surface 18 of the inner ring 12 is a flat cylindrical shape. The outer circumferential surface of the foot axle 32 has a convex curve bulging towards the inner circumferential surface 18 of the inner ring 12 in both the longitudinal and cross-sectional sections. Furthermore, the convex curve in the cross-section of the outer circumferential surface of the foot axle 32 has a shape that separates more from the cylindrical inner circumferential surface of the inner ring 12 as it approaches the axial sides of the coupling from the torque transmission direction end. Therefore, the circumferential length of the foot axle at the contact point between the outer circumferential surface of the foot axle 32 and the inner circumferential surface 18 of the inner ring 12 (i.e., the major axis of the contact ellipse) is shorter, thus reducing the force (torque) required to tilt the rollers.

[0074] Preferably, the outer peripheral surface 15 of the roller 11 is a flat cylindrical surface, and the roller guide surface 6 is a flat surface. With this configuration, under torque load, the flat roller guide surface 6 and the cylindrical outer peripheral surface 15 of the roller 11 press against each other through a straight contact portion, thereby suppressing the left and right tilting of the roller.

[0075] Preferably, the center of curvature of the convex portion of the cross-sectional shape of the foot shaft neck 29 coincides with the center of curvature of the end arc portion of the cross-sectional shape of the foot shaft 32. When the radius of curvature of the end arc portion of the cross-sectional shape of the foot shaft neck 29 is set to R´ and the radius of curvature of the convex portion of the cross-sectional shape of the foot shaft 32 is set to R, R´ < R. Particularly preferred is that R´ / R is set to 0.80 to 0.95. With this setting, the grinding machinability is stable and the strength of the foot shaft is also stable.

[0076] Preferably, when the minor axis dimension (neck width) of the cross-sectional shape of the foot axle neck 29 is set to W´, and the arcuate portion dimension (foot axle diameter) of the cross-sectional shape of the foot axle 32 is set to D, W´ / D is set to 0.70 to 0.90. By setting it in this way, it can be configured so that the neck 29 does not interfere with the inner ring 12 even when the maximum working angle is achieved.

[0077] Alternatively, when the width dimension of the foot shaft 32 in the minor axis direction of its cross-sectional shape is set to W, and the width dimension of the neck 29 in the minor axis direction of its cross-sectional shape is set to W´, then W´ = W. In this way, even if a portion of the foot shaft 32 with the same dimensions as the neck 29 is ground, it will not adversely affect the neck 29. Furthermore, areas with radial differences will not become areas with smaller radial differences, effectively preventing interference from the grinding wheel, cutting tools, etc., during the grinding of the foot shaft.

[0078] In addition, it can be used for constant velocity universal couplings with a maximum working angle of 23 to 28 degrees. That is, in a constant velocity universal coupling with such a maximum working angle, even when the working angle is reached, the clearance (journal clearance) between the foot shaft 32 and the inner circumferential surface of the inner roller unit (inner circumferential surface 18 of the inner ring 12) will not be negative, which can prevent the generation of abnormal noise and vibration, suppress circumferential wobble, and prevent the deterioration of NVH performance.

[0079] Next, Figures 9 to 10 The other three ball-and-pin components are shown. In this case, the minor axis length of the cross-section of the foot axle is set to be the same as the minor axis length of the cross-section shape of the neck 29. That is, when the minor axis length (foot axle width dimension) of the cross-section of the foot axle 32 is set to W, and the minor axis length (neck width dimension) of the cross-section shape of the neck 29 is set to W´, W is set to W´. Also in this case, when the radius of curvature of the arc 33b of the cross-section of the foot axle 32 is set to R, and the radius of curvature of the arc 29b of the cross-section of the neck 29 is set to R´, R is set to R>R´ and RR´ is set to constant.

[0080] Thus, even when using a three-ball pin member 3 with W=W´, it becomes an elongated oval shape with a larger wall thickness on the torque load side in its cross-sectional shape, and the wall thickness of the neck can be made thicker relative to the torque load direction of the three-ball pin member. Furthermore, conversely, the dimension (width dimension) in the direction orthogonal to the torque load direction can be smaller, and areas with radial differences will not form areas where the radial difference decreases. Therefore, it can achieve the same effect as the three-ball pin type constant velocity universal coupling using the three-ball pin member 3 shown in the above embodiment.

[0081] However, in the described embodiment, the neck 29, as Figure 12A As shown, it is designed as an elongated oval shape consisting of a pair of parallel straight lines and arcs at the ends. In contrast, as... Figure 12B As shown, instead of a pair of parallel straight sections 29c and 29d, the neck 29 is provided as a pair of arc-shaped sections 29e and 29f with a larger radius of curvature, i.e., a smaller curvature.

[0082] For those with Figure 12B The three-ball pin member 3 of the neck 29 shown in the figure needs to change its straight part 33c, 33d into a small arc-shaped part 33e, 33f with a small curvature in the cross-sectional shape of its foot shaft 32.

[0083] In this way, even for straight or slightly curved arc shapes, a radial difference can be set between the outer periphery of the foot shaft neck 29 and the outer periphery of the foot shaft 32, and the radial difference can be set to be constant, which can effectively prevent the grinding wheel, cutting tool, etc. from interfering with the neck 29 during the grinding process of the foot shaft 32.

[0084] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments and various modifications are possible. The radial difference between the outer periphery of the journal and the outer periphery of the journal can be arbitrarily set, but preferably, for example, about 0.05 to 0.20 times the diameter of the outer periphery of the journal. If it is less than 0.05 times, the radial difference is too small and the machinability deteriorates; conversely, if it exceeds 0.20 times, the strength of the journal may decrease. In addition, as a three-ball pin type constant velocity universal joint, it can be used in drive shafts equipped in the torque transmission system of motor vehicles, but of course, the application of constant velocity universal joints is not limited to motor vehicles. It can be widely used in general power transmission systems such as motor vehicles and industrial machinery.

[0085] [Industry Applicability]

[0086] This is a three-ball pin type constant velocity universal coupling with a double-row roller design and inner and outer rings. It enables high working angle and improves the grindability of the shaft.

[0087] [Explanation of Labels in the Attached Image]

[0088] 2. Outer coupling components

[0089] 3 Three-ball pin components

[0090] 4 Roller Units

[0091] 5. Straight raceway groove

[0092] 6 Roller Guide Surface

[0093] 11. Roller (outer ring)

[0094] 12 Inner Circle

[0095] 29. Axle neck

[0096] 31 Main Body

[0097] 32-pin hinge.

Claims

1. A three-ball pin type constant velocity universal joint, comprising: The outer coupling component has three raceway grooves extending along the coupling axial direction on its inner circumferential surface, and each raceway groove is provided with a pair of roller guide surfaces facing each other in the circumferential direction of the coupling. A three-ball pin assembly, disposed on the inner circumference of the outer coupling assembly, and having three foot pins protruding radially toward the raceway groove; and The three roller units include an inner ring disposed on the outer periphery of the axle and supported by the axle in a rotatable and swingable state, a roller disposed in the raceway groove and on the outer diameter side of the inner ring, and a plurality of rolling elements disposed between the inner ring and the roller and between the inner ring and the outer ring. The three-ball pin type constant velocity universal coupling is characterized by the following: For the outer peripheral surface of the foot axle, in both the longitudinal and cross sections, there are convex curves bulging outwards in the torque transmission direction. The center of curvature of the convex curve in the longitudinal section is offset relative to the central axis of the foot axle to the side opposite to the convex curve. Similarly, the center of curvature of the convex surface in the cross section is offset relative to the central axis of the foot axle to the side of the convex curve and to the rotation direction of the three ball pin components. When the radius of curvature of the convex curve in the longitudinal section is set to r, and the radius of curvature of the convex surface in the cross section is set to R, with r > R, the cross-sectional shape of the foot axle is set to an elongated oval shape. The three-ball pin component has a main body and a foot axle that protrudes in the radial direction of the coupling via a foot axle neck that is smaller than the foot axle. The cross-sectional shape of the foot axle neck is set to be an elongated oval shape, and a radial difference is provided between the arc-shaped portion of the outer periphery of the foot axle neck and the arc-shaped portion of the outer periphery of the foot axle.

2. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, The inner circumference of the inner ring is set as a cylinder.

3. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, The outer circumferential surface of the roller has a cylindrical shape, and the roller guide surface has a flat surface.

4. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, When the center of curvature of the convex portion of the cross-sectional shape of the foot shaft neck coincides with the center of curvature of the end arc portion of the cross-sectional shape of the foot shaft, and the radius of curvature of the end arc portion of the cross-sectional shape of the foot shaft neck is set to R´ and the radius of curvature of the convex portion of the cross-sectional shape of the foot shaft is set to R, then R´<R.

5. The three-ball pin type constant velocity universal coupling according to claim 4, characterized in that, Set R´ / R to 0.80~0.

95.

6. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, When the neck width dimension in the minor axis direction of the cross-sectional shape of the foot axle neck is set as W´, and the arc dimension of the cross-sectional shape of the foot axle, i.e., the foot axle diameter, is set as D, W´ / D is set to 0.70~0.

90.

7. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, When the neck width dimension in the minor axis direction of the cross-sectional shape of the foot axle is set to W, and the straight portion interval of the cross-sectional shape of the foot axle neck, i.e., the neck width dimension, is set to W´, then W´=W.

8. The three-ball pin type constant velocity universal coupling according to claim 1, characterized in that, The short axis side of the cross-sectional shape of the foot journal is either straight or a slightly curved arc.

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