Triple joint and inner joint portion of triple joint

Abstract

The present invention relates to a tripod joint (1). The tripod joint (1) comprises at least an outer joint portion (2), an inner joint portion (3), and a plurality of rotating bodies (4). The outer joint portion (2) has a receiving portion (6) for the inner joint portion (3) extending along a first rotation axis (5), and three raceways (9) extending along the first rotation axis (5) and distributed in the circumferential direction (7, 8). The inner joint portion (3) has a central body (11) extending along a second rotation axis (10), and three journals (14) extending from the central body (11) along the radial direction (12). Each journal has a journal axis (13) and is distributed in the circumferential direction (7, 8). One of the plurality of rotating bodies (4) is disposed on each of the journals (14), and the rotating body (4) contacts the journal (14) with an inner circumferential surface (15) and contacts each raceway (9) with an outer circumferential surface (16). The present invention further relates to the inner joint portion (3).

Description

Technical Field

[0001] The present invention relates to a tripod joint and an inner joint portion of a tripod joint, particularly to the inner joint portion of the specifically described tripod joint.

Background Art

[0002] A tripod joint generally includes at least an outer joint portion having a first rotation axis and an inner joint portion having a second rotation axis. The inner joint portion includes a central body having three integrally formed journals. Rotating bodies are arranged on each journal. In particular, the inner joint portion can move relative to the outer joint portion along the first rotation axis. Further, the inner joint portion can tilt relative to the outer joint portion, that is, the first rotation axis and the second rotation axis can be arranged relative to each other at a so-called bending angle.

[0003] This type of joint is known, for example, from Patent Document 1. The outer joint portion has a longitudinal axis (the first rotation axis) and a cavity (receptacle) that extends along the longitudinal axis and has at least one open end, and three recesses (raceways) that extend parallel to the longitudinal axis are formed in the outer joint portion. The inner joint portion has a (different) longitudinal axis (the second rotation axis) and a central body in which three journals are formed, and each journal has a journal axis that extends radially from the longitudinal axis. Rotating bodies are arranged on each journal. The rotating bodies are respectively accommodated in the recesses of the outer joint portion and move in the longitudinal direction. The rotating bodies can be arranged on the journals via a bearing body (rolling element) or via a further inner ring. In particular, the rotating body has at least one outer ring and a bearing body, and may optionally have an inner ring, whereby the bearing body is arranged between the outer ring and the inner ring.

[0004] Tripod joints have long been manufactured and sold by the applicant, for example, under the name AAR tripod joint. These tripod joints are used for the side shafts of automobiles, and in particular, they serve as drive connections between the differential gear and the drive wheels. On the wheel side, so-called constant velocity ball joints are usually used, and the AAR tripod joints mentioned here are used as adjacent sliding joints on the differential gear. The AAR tripod joints are particularly designed for bending angles on the order of 23 to 26 degrees (or less).

[0005] The journal contacts each bearing or the inner ring of the rotating body via so-called sliding surfaces (contact surfaces). Each sliding surface is specifically designed in the shape of a ball joint. These sliding surfaces are aligned circumferentially, and torque acting around the joint's multiple longitudinal axes is transmitted to the rotating body and from the rotating body to the recesses (or vice versa) via each sliding surface of the journal.

[0006] In the towing operation of an automobile, that is, when the automobile is driven by the drive unit, the journal contacts one sliding surface of the rotating body, and the rotating body contacts only one side of the recess in particular. In engine braking conditions, or when the automobile is coasting, that is, when driving torque is being applied from the wheels and the drive unit is still connected (engine braking condition) or disconnected (coasting condition), the journal contacts the other sliding surface of the rotating body, and the rotating body contacts only the opposite side of the recess. In engine braking and coasting conditions, the direction of the applied torque and the direction of rotation of the joint are opposite to each other, while in the towing condition, they are in the same direction.

[0007] To achieve particularly advantageous guiding characteristics, an offset is provided between the first pitch radius of the sliding surface of each journal and the second pitch radius of each recess.

[0008] The pitch radius of each journal is the so-called effective radius. This is defined for an extended (non-bent) joint, that is, when each longitudinal axis or each rotation axis is arranged coaxially with respect to each other. The effective radius determines the lever arm of the resultant force when torque is transmitted. Therefore, the pitch circle radius of each journal is the radius originating from the longitudinal axis of the inner joint portion, and for example, when the joint is extended, the centers of each trapezoidal sliding surface of the journal are located on this radius.

[0009] The pitch radius of the outer joint portion or recess is also a so-called effective radius. This is defined for extended joints, i.e., when each longitudinal axis or each rotation axis is arranged coaxially with respect to one another. The effective radius determines the lever arm of the resultant force when torque is transmitted.

[0010] The definition of the pitch circle radius (also known as the PCR) is generally known, and is particularly well known for tripod joints.

[0011] Therefore, the offset of each pitch circle radius is the difference between these pitch circle radii.

[0012] Furthermore, the characteristics of a tripod joint are determined in particular by the so-called ACFG value (Axial Cyclic Force Generation, the unwanted axial force generated by the joint). This value is given as the root mean square of the force, and its unit is Newtons' root mean square [Nrms]. The value varies as a function of the joint's bending angle, thereby allowing the progression of the value to be defined or determined for each joint as a function of the bending angle. The range in which the joint can be used is thus limited by the maximum bending angle. At this maximum bending angle, the ACFG value does not exceed a level considered acceptable. [Prior art documents] [Patent Documents]

[0013] [Patent Document 1] International Publication No. 2009 / 052857 [Patent Document 2] German Patent Application Publication No. 4130183 [Overview of the project] [Problems that the invention aims to solve]

[0014] The object of the present invention is to solve, at least partially, the problems described in relation to the prior art. In particular, the invention proposes a tripod-type joint or an inner joint portion of a tripod-type joint that exhibits particularly favorable behavior with respect to the ACFG value. [Means for solving the problem]

[0015] A tripod-type joint having the features of claim 1 and an inner joint portion having the features of claim 10 contribute to solving these problems. Advantageous developments are the subject matter of the dependent claims. The features enumerated in the claims can be combined in technically feasible ways and may be supplemented by the descriptive technical content and photographic details of this specification, which disclose further embodiments of the present invention.

[0016] We propose a tripod-type joint (hereinafter referred to as "the joint"). This joint comprises at least an outer joint portion, an inner joint portion, and a plurality of rotating bodies. In particular, the tripod-type joint is a sliding joint, and the inner joint portion is movable along a first rotation axis relative to the outer joint portion.

[0017] The outer joint portion has a receiving portion for the inner joint portion that extends along the first rotation axis, and three raceway surfaces that extend along the first rotation axis and are evenly distributed in the circumferential direction.

[0018] The inner joint portion has a central body extending along the second rotation axis and three journals extending radially from the central body, each journal having a journal axis and being (evenly) distributed in the circumferential direction.

[0019] A rotating body is positioned in each journal, and the rotating body contacts the journal with its inner surface and the respective raceway surface with its outer surface. Each journal has a contact surface for contacting its inner surface, the first contact surface oriented in at least a first circumferential direction, and the second contact surface oriented in at least a second circumferential direction, the second circumferential direction being opposite to the first circumferential direction. When the axes of rotation are arranged coaxially with respect to each other, the first contact surface has a first pitch circle radius, the second contact surface has a second pitch circle radius, and the raceway surface has a third pitch circle radius, and at least the first and second pitch circle radii are different from each other.

[0020] In particular, the outer circumferential surface of a rotating body is rotatable relative to its inner circumferential surface. The inner circumferential surface is formed, for example, by a journal or by an inner ring or rolling elements that contact each contact surface. When the inner circumferential surface is formed by an inner ring, each rolling element is positioned between the inner ring and the outer circumferential surface, thereby enabling relative rotation.

[0021] The rotation of the inner surface relative to the outer surface allows the rotating body to roll along the raceway surface, thereby allowing the inner joint portion to be displaced along the first axis of rotation relative to the outer joint portion.

[0022] As the inner joint section tilts, the rotating body is further guided through the raceway surface, causing at least each journal to tilt relative to each rotating body.

[0023] In particular, each rotating body is guided through the raceway surface so that the rotating body does not tilt relative to the raceway surface.

[0024] Alternatively, if the inner joint section tilts, the rotating body will also tilt relative to the raceway surface.

[0025] In particular, the inner circumferential surface and the outer circumferential surface do not perform any further relative movement with respect to each other, apart from the relative rotation.

[0026] As defined above, the pitch circle radius of each journal is, in particular, the so-called effective radius. This is defined for an extended joint, i.e., when the respective axes of rotation are arranged coaxially with respect to each other. The effective radius determines the lever arm of the resultant force when torque is transmitted. Therefore, the pitch circle radius of each journal is a radius starting from the second axis of rotation. For example, when the joint is extended, the center of each sliding surface of the spherical seat of the journal is arranged on this radius.

[0027] As defined above, the pitch radius of the outer joint part or the raceway surface is the so-called effective radius, which is defined for an extended joint, i.e., when the respective longitudinal axes or the respective axes of rotation are arranged coaxially with respect to each other. The effective radius determines the lever arm of the resultant force when torque is transmitted.

[0028] The pitch circle radius is defined, in particular, with respect to the spherical surface (of the journal or the outer joint part). If the shape deviates from a spherical surface (for example, if the surface or its contour is elliptical, or has a spline contour or a torus contour), the actual contact point of the resultant force can be used on that surface.

[0029] The offset provided in a known joint is between the first pitch radius of the sliding surface of the journal and the second pitch radius of the recess. When the joint is used in the engine braking state / coasting state or the traction state, it has been found that the ACFG value or its transition varies according to the bending angle. However, in these joints, the offset can only be set at the best compromise point, so an ACFG value that is equally suitable for both the engine braking state / coasting state and the traction state is obtained.

[0030] The proposed tripod-type joint has different pitch circle radii for each contact surface, allowing it to adapt to engine braking or coasting conditions on the one hand, and to towing conditions on the other. Therefore, the contact surfaces oriented in different circumferential directions have different characteristics, namely different pitch circle radii. Thus, by adapting one (e.g., the first) pitch radius, the ACFG value of the joint can be designed specifically for engine braking or coasting conditions, and by adapting the other (e.g., the second) pitch radius, the ACFG value can be designed specifically for towing conditions.

[0031] The first pitch circle radius and the second pitch circle radius differ by a coefficient of at least 1.001, preferably by a coefficient of at least 1.005, and most preferably by a coefficient of at least 1.01.

[0032] In particular, the radius of the first pitch circle is either smaller or larger than the radius of the third pitch circle.

[0033] In particular, the radius of the second pitch circle is either larger or smaller than the radius of the third pitch circle.

[0034] In particular, the value of the first or second pitch circle radius corresponds to the value of the third pitch circle radius.

[0035] In particular, the third pitch circle radius is either larger or smaller than the first and second pitch circle radii.

[0036] In particular, all ratios between pitch circle radii are possible, and as a result, the first pitch circle radius and the second pitch circle radius are always different from each other or have different values.

[0037] In particular, the contact surfaces are spherical. However, the contours of each contact surface can deviate from a spherical shape. For example, each contact surface can be formed by several different radii of curvature. The starting points of the radii may or may not be located on the respective journal axes. The contact surfaces can also be elliptical or toroidal.

[0038] In particular, the inner circumferential surface contacts the surface of each contact surface at only one point in the cross-section extending laterally with respect to the second rotation axis.

[0039] In particular, each raceway surface is curved in a cross-section extending laterally with respect to the first axis of rotation. In particular, the shape of the raceway surface in this cross-section is formed by one or more radii. In particular, the curvature is concave with respect to the outer surface of the rotating body. In particular, the transition of the curvature is a pointed arch shape, also known as a pointed arch. In particular, the outer surface contacts the surface of each raceway surface 9 in the cross-section at one point, two points, or along a line.

[0040] The contact between each of the above surfaces is described only in an idealized form. For example, when a convex curved surface contacts a cylindrical (zylindrische) surface, while the elastic deformation of each surface may actually result in linear contact, from an idealized perspective, contact occurs at only one point.

[0041] In particular, each rotating body comprises an inner ring having an inner circumferential surface, an outer ring having an outer circumferential surface, and a plurality of rolling elements between the inner and outer rings.

[0042] In particular, the outer surface has a convex shape relative to each raceway surface.

[0043] In particular, the inner surface is cylindrical.

[0044] In particular, the inner circumferential surface is concave with respect to each contact surface. In this context, concave means that the inner circumferential surface has a central region that is recessed relative to each contact surface, and an outer region adjacent to the central region that protrudes toward each contact surface.

[0045] The central region can be cylindrical or concave. In particular, the curvature of the concave surface of the central region may extend to the outer region at a constant or varying radius. The outer region may have a conical shape starting from the (curved or cylindrical) central region.

[0046] The concave design of the inner surface allows the rotating body or inner ring to be fixed onto the journal during the operation of the tripod joint. In particular, this means that the inner ring does not need to be fixed to the outer ring.

[0047] Typically, such a fixation is designed so that the inner ring can only rotate relative to the outer ring. However, although this fixation is usually done with a retaining / locking ring on the outer ring or inner ring, if the inner joint portion is displaced along the first rotation axis, frictional losses occur because only the outer ring performs rotational motion around the journal axis.

[0048] The concave design of the inner surface serves to secure the inner ring above each journal, while the outer surface is guided by or fixed by the raceway (for example, in the circumferential and radial directions around the first axis of rotation).

[0049] In particular, each contact surface extends over an angular range that spreads out from its respective journal axis, and the angular range has an angle of less than 180 degrees, in particular an angle of less than 150 degrees, and preferably an angle of less than 130 degrees.

[0050] In particular, the inner joint portion has a central cross-section, which extends laterally with respect to the second rotation axis and intersects with the center of mass of the inner joint portion. In this cross-section, the inner joint portion has a minimum thickness (the sum of the first and second thicknesses) between the central body and each contact surface, along the radial direction or along each respective journal axis. The first thickness, extending from the journal axis to the first surface of the inner joint portion adjacent to the first contact surface, is less than or greater than the second thickness, extending from the journal axis to the second surface of the inner joint portion adjacent to the second contact surface. The difference between the first and second thicknesses is at least 1 percent of the greater thickness, preferably at least 5 percent.

[0051] Further proposals are made for an internal joint portion for a tripod-type joint. In particular, the internal joint portion for the tripod-type joint described above is proposed. Specifically, the internal joint portion comprises at least a central body extending along a second axis of rotation and three journals extending radially from the central body, each journal having a journal axis and being distributed circumferentially. Each journal has a contact surface for contacting the rotating body of the tripod-type joint. The first contact surface is oriented at least in a first circumferential direction, and the second contact surface is oriented at least in a second circumferential direction, the second circumferential direction being opposite to the first circumferential direction. The first contact surface has a first pitch circle radius, and the second contact surface has a second pitch circle radius, the first pitch circle radius and the second pitch circle radius being of different values.

[0052] The inner joint portion or at least each contact surface can be manufactured by a machining process (e.g., turning, milling, grinding) or a forming process (e.g., forging).

[0053] The description regarding tripod-type joints is particularly applicable to the internal joint portion, and vice versa.

[0054] The tripod joint described, or the tripod joint with the described internal joint portion, is particularly suitable for use in the side shafts of automobiles. In particular, the side shafts are connected to the drive unit of the automobile, thereby enabling the torque of the drive unit to be transmitted to the wheels of the automobile via the tripod joint.

[0055] The indefinite articles ("ein," "eine," "einer," "eines") are intended to be understood as they are, not as numerals, particularly in the claims and descriptions that reiterate those claims. Therefore, the corresponding terms and elements introduced are intended to be understood as appearing at least once, but possibly several times.

[0056] To avoid any doubt, the ordinal numbers used herein ("first," "second," etc.) are used primarily to distinguish several similar objects, numbers, or processes, and not in any particular sense, these ordinal numbers do not necessarily define any dependencies or order between these objects, numbers, or processes. Where dependencies or order are necessary, this will be explicitly stated herein or will become apparent to a person skilled in the art by examining the configuration actually described.

[0057] The present invention and its technical environment will be described in more detail below with reference to the attached figures. It should be noted that the present invention is not limited by the design modifications described. In particular, it should be noted that the figures and especially the proportions shown are for illustrative purposes only. [Brief explanation of the drawing]

[0058] [Figure 1] This is the side shaft of a vehicle in a towed state. [Figure 2]This is the side shaft shown in Figure 1, in the state of engine braking or coasting. [Figure 3] This shows a known tripod-type joint from a viewpoint along a coaxially arranged axis of rotation. [Figure 4] This is a tripod-type joint according to Patent Document 2. [Figure 5] The first figure is shown. [Figure 6] The second figure is shown. [Figure 7] Figure 3 shows a tripod-type joint having a driven outer joint portion. [Figure 8] This shows a tripod-type joint with a driven outer joint portion, viewed from a perspective along the coaxial axis of rotation. [Figure 9] Figures 3 and 7 show tripod-type joints having a driven internal joint portion. [Figure 10] Figure 8 shows a tripod-type joint having a driven internal joint portion. [Figure 11] Figures 3, 4, and 7-10 show the outer joint portion of the tripod-type joint. [Figure 12] This is the first design modification example of the inner joint section from a viewpoint along the second rotation axis. [Figure 13] This is a second design modification example of the inner joint section, viewed from a perspective along the second axis of rotation. [Figure 14] The third figure is shown. [Figure 15] The fourth figure is shown. [Figure 16] This shows a portion of the inner joint section in the third design modification example, viewed from a perspective along the second rotation axis. [Figure 17] This shows a portion of the inner joint section in the fourth design modification example, viewed from a perspective along the second rotation axis. [Figure 18] This is the inner joint section from a viewpoint along the second axis of rotation. [Figure 19] This is the inner joint portion in Figure 18, viewed from a perspective along the journal axis. [Figure 20] The inner joint portion in Figures 18 and 19 is shown in a side view. [Figure 21] Figures 18-20 show a tripod-type joint with an inner joint portion, viewed from a perspective along the axis of rotation, and partially shown in cross-section. [Figure 22] This is the inner joint portion with a rotating body in Figure 21, viewed from a perspective along the journal axis. [Figure 23] This is the inner joint portion with the rotating body in Figure 22, viewed from a perspective along the second axis of rotation, and is partially shown in cross-section. [Figure 24] Figure 21 shows a tripod-type joint in both a side view and a cross-sectional view. [Figure 25] This is a third design modification example of the inner joint section, viewed from a perspective along the second rotation axis. [Figure 26] This is a detailed view of the inner joint portion in Figure 26, from a perspective along the second axis of rotation. [Figure 27] This is a detailed example of the fourth design modification of the inner joint section, viewed from a perspective along the second rotation axis. [Modes for carrying out the invention]

[0059] Figure 1 shows the side shaft 26 of the automobile 27 in a towed state. The side shaft 26 connects the wheel 30 of the automobile 27 to the drive unit 28 or gearbox 38. The side shaft 26 has a tripod-type joint 1 on the drive unit 28 side or the gearbox 38 side, and a joint 29 on the wheel 30 side. In the towed state, the direction of the applied torque 31 and the direction of rotation of the side shaft 26 are the same (see arrow).

[0060] Figure 2 shows the side shaft 26 in the engine braking state or coasting state as shown in Figure 1. Please refer to the explanation of Figure 1. In the engine braking state or coasting state, the direction of the applied torque 31 and the direction of rotation of the side shaft 26 are opposite to each other.

[0061] Figure 3 shows a known tripod-type joint 1 from a viewpoint along coaxially arranged rotation axes 5 and 10. Figure 4 shows a tripod-type joint 1 according to Patent Document 2. Figures 3 and 4 will be explained below. Please refer to the explanation for Figures 1 and 2.

[0062] The tripod-type joint 1 comprises an outer joint portion 2, an inner joint portion 3, and a plurality of rotating bodies 4. The tripod-type joint 1 is a sliding joint, and the inner joint portion 3 is movable relative to the outer joint portion 2 along a first rotation axis 5. The outer joint portion 2 has a receiving portion 6 for the inner joint portion 3 that extends along the first rotation axis 5, and three raceway surfaces 9 that extend along the first rotation axis 5 and are evenly distributed in the circumferential directions 7 and 8. The inner joint portion 3 has a central body 11 that extends along a second rotation axis 10, and three journals 14 that extend from the central body 11 in the radial direction 12. Each journal has a journal axis 13 and is evenly distributed in the circumferential directions 7 and 8.

[0063] A rotating body 4 is positioned on each journal 14, the rotating body 4 in contact with the journal 14 at its inner surface 15 and with the respective raceway surface 9 at its outer surface 16. Each journal 14 has contact surfaces 17, 18 for contacting the inner surface 15, the first contact surface 17 being oriented at least in a first circumferential direction 7, and the second contact surface 18 being oriented at least in a second circumferential direction 8, opposite to the first circumferential direction 7. When the rotating axes 5, 10 are arranged coaxially with respect to each other, the first and second contact surfaces 17, 18 have a first pitch radius 19, and the raceway surface 9 has a third pitch radius 21.

[0064] In order to achieve particularly advantageous guiding characteristics, an offset 32 ​​is provided between the first pitch radius 19 of the contact surfaces 17 and 18 of each journal 14 and the third pitch radius 21 of the raceway surface 9.

[0065] Each rotating body 4 comprises an inner ring 22 having an inner circumferential surface 15, an outer ring 23 having an outer circumferential surface 16, and a plurality of rolling elements 24 between the inner ring 22 and the outer ring 23.

[0066] When the vehicle 27 is towed, that is, when the vehicle 27 is driven by the drive unit 28, the journal 14 is in contact with the rotating body 4 on one of the contact surfaces 17 and 18, and the rotating body 4 is in contact with only one side of the raceway surface 9. When the vehicle 27 is in engine braking or coasting mode, that is, when drive torque is being introduced from the wheel 30 and the drive unit 28 is still connected (engine braking) or disconnected (coasting), the journal 14 is in contact with the rotating body 4 on the other of the contact surfaces 18 and 17, and the rotating body 4 is in contact with only the other side of the raceway surface 9.

[0067] Figure 5 shows the first figure. Figure 6 shows the second figure. Figures 5 and 6 are explained together. The ACFG value 34 is plotted on the vertical axis in [Nrms], and the bending angle 33 of the tripod-type joint 1 is plotted on the horizontal axis in [angle (degrees)].

[0068] The ACFG value 34 changes as a function of the bending angle 33 of the tripod-type joint 1, thereby determining the transition 35 of the value as a function of the bending angle 33, which can be determined for each tripod-type joint 1. Therefore, the range of application of the tripod-type joint 1 is limited by the maximum bending angle 33. This maximum bending angle 33 is the bending angle at which the ACFG value 34 exceeds the maximum value 36 considered acceptable.

[0069] Figure 5 shows the transition 35 of the traction state of the tripod-type joint 1 in Figures 3 and 4. Figure 6 shows the transition 35 of the engine braking state / coasting state of this tripod-type joint 1. The range of application of the tripod-type joint 1 is limited by the bending angle 33, and it can be seen that this bending angle 33 is exceeded by the maximum value 36 of the ACFG value 34 that is considered acceptable in the engine braking state / coasting state.

[0070] Figure 7 shows the tripod-type joint 1 in Figure 3, which has a driven outer joint portion 2. The arrows indicate the combined torque 31 acting on the effective radius of the outer joint portion 2.

[0071] Figure 8 shows a tripod-type joint 1 having a driven outer joint portion 2, viewed from a perspective along coaxially arranged rotation axes 5 and 10. The tripod-type joint 1 comprises an outer joint portion 2, an inner joint portion 3, and a plurality of rotating bodies 4. The tripod-type joint 1 is a sliding joint, and the inner joint portion 3 is movable relative to the outer joint portion 2 along the first rotation axis 5. The outer joint portion 2 has a receiving portion 6 for the inner joint portion 3 that extends along the first rotation axis 5, and three raceway surfaces 9 that extend along the first rotation axis 5 and are evenly distributed in the circumferential directions 7 and 8. The inner joint portion 3 has a central body 11 that extends along the second rotation axis 10, and three journals 14 that extend from the central body 11 in the radial direction 12. Each journal has a journal axis 13 and is evenly distributed in the circumferential directions 7 and 8.

[0072] A rotating body 4 is positioned on each journal 14, and the rotating body 4 contacts the journal 14 with its inner circumferential surface 15 and contacts the respective raceway surface 9 with its outer circumferential surface 16. Each journal 14 has contact surfaces 17 and 18 for contacting the inner circumferential surface 15, the first contact surface 17 being oriented at least in the first circumferential direction 7 and the second contact surface 18 being oriented in at least the second circumferential direction 8, opposite to the first circumferential direction 7.

[0073] Each rotating body 4 comprises an inner ring 22 having an inner circumferential surface 15, an outer ring 23 having an outer circumferential surface 16, and a plurality of rolling elements 24 between the inner ring 22 and the outer ring 23.

[0074] When the rotating shafts 5 and 10 are arranged coaxially with respect to each other, the first contact surface 17 has a first pitch circle radius 19, the second contact surface 18 has a second pitch circle radius 20, and the raceway surface 9 has a third pitch circle radius 21, and at least the first pitch circle radius 19 and the second pitch circle radius 20 have different values ​​from each other.

[0075] The outer circumferential surface 16 of the rotating body 4 is rotatable relative to the inner circumferential surface 15 of the rotating body 4. The inner circumferential surface 15 is formed by an inner ring 22 that contacts the journal 14 or contact surfaces 17, 18. A rolling element 24 is positioned between the inner ring 22 and the outer circumferential surface 16, thereby enabling relative rotation.

[0076] The rotation of the inner circumferential surface 15 relative to the outer circumferential surface 16 allows the rotating body 4 to roll along the raceway surface 9, thereby allowing the inner joint portion 3 to be displaced along the first rotation axis 5 relative to the outer joint portion 2.

[0077] As the inner joint portion 3 tilts, the rotating body 4 is further guided via the raceway surface 9, thereby causing the journal 14 to tilt relative to the rotating body 4.

[0078] The inner surface 15 and the outer surface 16 do not perform any further relative motion with respect to each other, apart from their relative rotation.

[0079] The pitch circle radii 19 and 20 of each journal 14 are the so-called effective radii. This is defined for the case of an extended tripod-type joint 1, i.e., when the rotating shafts 5 and 10 are arranged coaxially with respect to each other. The effective radius determines the lever arm of the resultant force when the torque 31 (see arrow in Figure 8) is transmitted. Therefore, the pitch circle radii 19 and 20 of each journal 14 are radii originating from the second rotating shaft 10, and when the tripod-type joint 1 is extended, the centers of the trapezoidal contact surfaces 17 and 18 of the journal 14 are located on this radius.

[0080] The proposed tripod-type joint 1 has different pitch circle radii 19 and 20 on each contact surface 17 and 18. This tripod-type joint 1 allows for adaptation to engine braking or coasting conditions, and towing conditions. Therefore, the contact surfaces 17 and 18 oriented in different circumferential directions 7 and 8 have different characteristics, namely different pitch circle radii 19 and 20. Thus, by adjusting the first pitch radius 19, the ACFG value 34 of the tripod-type joint 1 can be designed specifically for engine braking or coasting conditions, and by adjusting the second pitch radius 20, the ACFG value 34 can be designed specifically for towing conditions.

[0081] Here, the second pitch circle radius 20 is smaller than the third pitch circle radius 21, and the first pitch circle radius 19 is larger than the third pitch circle radius 21.

[0082] Figure 9 shows the tripod-type joint 1 in Figures 3 and 7, which has a driven inner joint portion 3. See Figure 7. The arrows indicate the effective radius of the outer joint portion 2 and the combined torque 31 acting on the third pitch radius 21.

[0083] Figure 10 shows the tripod-type joint 1 in Figure 8, which has a driven inner joint portion 3. Please refer to Figure 8. The arrows indicate the effective radius of the outer joint portion 2 and the combined torque 31 acting on the third pitch circle radius 21.

[0084] Figure 11 shows the outer joint portion 2 of the tripod-type joint 1 in Figures 3, 4, and 7-10. The outer joint portion 2 has a receiving portion 6 for the inner joint portion 3 that extends along the first rotation axis 5, and three raceway surfaces 9 that extend along the first rotation axis 5 and are evenly distributed in the circumferential directions 7 and 8.

[0085] Each raceway surface 9 is curved in the illustrated cross-section, extending laterally with respect to the first axis of rotation 5. The shape of the raceway surface 9 in this cross-section is formed by multiple radii. The curvature is concave with respect to the outer surface 16 of the rotating body 4. The transition of the curvature is a pointed arch shape, also known as a pointed arch. The outer surface 16 contacts the surface of the raceway surface 9 at two points in the cross-section (see also Figures 7-10).

[0086] The outer joint portion 2 has each raceway surface 9 positioned on the third pitch circle radius 21.

[0087] Figure 12 shows a first design modification example of the inner joint portion 3 from a viewpoint along the second rotation axis 10. Please refer to the description of Figure 10 and the inner joint portion 3 described therein.

[0088] Each journal 14 has contact surfaces 17, 18 for contacting the inner circumferential surface 15, the first contact surface 17 being oriented at least in a first circumferential direction 7, and the second contact surface 18 being oriented at least in a second circumferential direction 8, opposite to the first circumferential direction 7. The first contact surface 17 has a first pitch circle radius 19, and the second contact surface 18 has a second pitch circle radius 20, with the first pitch circle radius 19 being greater than the second pitch circle radius 20.

[0089] Figure 13 shows a second design modification example of the inner joint portion 3 from a viewpoint along the second rotation axis 10. Please refer to the explanation for Figure 12.

[0090] In contrast to the first design modification example, here the first pitch circle radius 19 is smaller than the second pitch circle radius 20.

[0091] Figure 14 shows the third figure. Figure 15 shows the fourth figure. Please refer to the explanations for Figures 5 and 6. Figures 14 and 15 will be explained together.

[0092] The ACFG values ​​34 are plotted on the vertical axis in [Nrms], and the bending angle 33 of tripod-type joint 1 is plotted on the horizontal axis in [angle (degrees)].

[0093] The ACFG value 34 changes as a function of the bending angle 33 of the tripod-type joint 1, thereby determining the transition 35 of the value as a function of the bending angle 33, which can be determined for each tripod-type joint 1. Therefore, the range of application of the tripod-type joint 1 is limited by the maximum bending angle 33. This maximum bending angle 33 is the bending angle at which the ACFG value 34 exceeds the maximum value 36 considered acceptable.

[0094] Figure 14 shows the transition 35 of the traction state of the tripod-type joint 1 in Figures 8 and 10-13. Figure 15 shows the transition 35 of the engine braking state / coasting state of this tripod-type joint 1. The applicability range of the tripod-type joint 1 is limited only by a fairly large value of the bending angle 33, and it can be seen that in both operating states, the ACFG value 34 is exceeded by the maximum value 36 considered acceptable.

[0095] Figure 16 shows a portion of the inner joint section 3 in the third design modification example, viewed from a perspective along the second rotation axis 10. Here, the journal 14 is manufactured by a machining process. The rotation axis 37 of the journal geometry (Zapfengeometrie) used in the manufacturing process can be seen.

[0096] Figure 17 shows a portion of the inner joint section 3 in the fourth design modification example, viewed from a perspective along the second rotation axis 10. Here, the journal 14 is manufactured by a forging process.

[0097] Figure 18 shows the inner joint portion 3 from a viewpoint along the second rotation axis 10. Figure 19 shows the inner joint portion 3 in Figure 18 from a viewpoint along the journal axis 13. Figure 20 shows the inner joint portion 3 in Figures 18 and 19 in a side view. Figures 18 to 20 are explained below. Please refer to the explanations of Figures 8 and 10 to 17.

[0098] Each journal 14 has contact surfaces 17, 18 for contacting the inner circumferential surface 15, the first contact surface 17 being oriented at least in a first circumferential direction 7, and the second contact surface 18 being oriented at least in a second circumferential direction 8, opposite to the first circumferential direction 7.

[0099] Each contact surface 17, 18 extends over an angular range 25 that spreads out from the respective journal axis 13, and this angular range has an angle of less than 150 degrees.

[0100] The inner joint portion 3 has a central cross-section 41, which extends laterally with respect to the second rotation axis 10 and intersects with the center of mass 42 of the inner joint portion 3. In this central cross-section 41, the inner joint portion 3 has a minimum thickness (the sum of the first thickness 43 and the second thickness 45) between the central body 11 and each contact surface 17, 18, along the radial direction 12 or along each journal axis 13. The first thickness 43, which extends from the journal axis 13 to the first surface 44 of the inner joint portion 3 adjacent to the first contact surface 17, is smaller than the second thickness 45, which extends from the journal axis 13 to the second surface 46 of the inner joint portion 3 adjacent to the second contact surface 18.

[0101] Figure 21 shows the tripod-type joint 1 with the inner joint portion 3 shown in Figures 18-20, viewed from a viewpoint along the rotation axes 5 and 10, and is partially shown in cross-section. Figure 22 shows the inner joint portion 3 with the rotating body 4 shown in Figure 21, viewed from a viewpoint along the journal axis 13. Figure 23 shows the inner joint portion 3 with the rotating body 4 shown in Figure 22, viewed from a viewpoint along the second rotation axis 10, and is partially shown in cross-section. Figure 24 shows the tripod-type joint in Figure 21 in both a side view and a cross-sectional view. Figures 21-24 are explained below. Please refer to the explanations for Figures 8 and 10-20.

[0102] The tripod-type joint 1 comprises an outer joint portion 2, an inner joint portion 3, and a plurality of rotating bodies 4. The tripod-type joint 1 is a sliding joint, and the inner joint portion 3 is movable relative to the outer joint portion 2 along a first rotation axis 5. The outer joint portion 2 has a receiving portion 6 for the inner joint portion 3 that extends along the first rotation axis 5, and three raceway surfaces 9 that extend along the first rotation axis 5 and are evenly distributed in the circumferential directions 7 and 8. The inner joint portion 3 has a central body 11 that extends along a second rotation axis 10, and three journals 14 that extend from the central body 11 in the radial direction 12. Each journal has a journal axis 13 and is evenly distributed in the circumferential directions 7 and 8.

[0103] A rotating body 4 is positioned on each journal 14, and the rotating body 4 contacts the journal 14 with its inner circumferential surface 15 and contacts the respective raceway surface 9 with its outer circumferential surface 16. Each journal 14 has contact surfaces 17, 18 as described in relation to Figures 18-20 in order to contact the inner circumferential surface 15, the first contact surface 17 being oriented at least in the first circumferential direction 7, and the second contact surface 18 being oriented at least in the second circumferential direction 8, opposite to the first circumferential direction 7.

[0104] The outer circumferential surface 16 of the rotating body 4 is rotatable relative to the inner circumferential surface 15 of the rotating body 4. The inner circumferential surface 15 is formed by an inner ring 22 that contacts the journal 14 or contact surfaces 17, 18. A rolling element 24 is positioned between the inner ring 22 and the outer circumferential surface 16, thereby enabling relative rotation.

[0105] The rotation of the inner circumferential surface 15 relative to the outer circumferential surface 16 allows the rotating body 4 to roll along the raceway surface 9, thereby allowing the inner joint portion 3 to be displaced along the first rotation axis 5 relative to the outer joint portion 2.

[0106] As the inner joint portion 3 tilts, the rotating body 4 is further guided via the raceway surface 9, thereby causing the journal 14 to pivot relative to the rotating body 4. The bending angle 33 set between the first rotation axis 5 and the second rotation axis 10 is shown in Figure 24.

[0107] The inner surface 15 and the outer surface 16 do not perform any further relative motion with respect to each other, apart from their relative rotation.

[0108] The proposed tripod-type joint 1 has different pitch circle radii 19 and 20 on each contact surface 17 and 18. This tripod-type joint 1 allows for adaptation to engine braking or coasting conditions on the one hand, and towing conditions on the other.

[0109] Here, the second pitch circle radius 20 is smaller than the third pitch circle radius 21, and the first pitch circle radius 19 is larger than the third pitch circle radius 21.

[0110] Each rotating body 4 comprises an inner ring 22 having an inner circumferential surface 15, an outer ring 23 having an outer circumferential surface 16, and a plurality of rolling elements 24 between the inner ring 22 and the outer ring 23. The outer circumferential surface 16 has a convex shape with respect to the raceway surface 9. The inner circumferential surface 15 is cylindrical.

[0111] Figure 25 shows a third design modification example of the inner joint portion 3 from a viewpoint along the second rotation axis 10. Figure 26 shows details of the inner joint portion 3 in Figure 26 from a viewpoint along the second rotation axis 10. Figure 27 shows details of a fourth design modification example of the inner joint portion 3 from a viewpoint along the second rotation axis 10.

[0112] In contrast to the first and second design modification examples, the inner circumferential surface 15 is concave with respect to each contact surface 17, 18. In this context, concave means that the inner circumferential surface 15 has a central region 39 that is recessed relative to each contact surface 17, 18, and an outer region 40 adjacent to the central region 39 that protrudes toward each contact surface 17, 18.

[0113] In the third and fourth design modification examples, the central region 39 is cylindrical. In the third design modification example, each outer region 40 has a curved shape (see Figure 26). In the fourth design modification example, each outer region 40 has at least a partially conical shape, starting from the cylindrical central region 39.

[0114] The concave design of the inner circumferential surface 15 allows the rotating body 4 or the inner ring 22 to be fixed on the journal 14 during the operation of the tripod-type joint 1. This means that the inner ring 22 does not need to be fixed to the outer ring 23.

[0115] Typically, such a fixation is provided so that the inner ring 22 can only rotate relative to the outer ring 23. However, although this fixation is usually done by a retaining / locking ring on the outer ring 23 or the inner ring 22, if the inner joint portion 3 is displaced along the first rotation axis 5, frictional losses occur because only the outer ring 23 performs rotational motion around the journal axis 13.

[0116] The inner circumferential surface 15 is designed to be concave, which serves to secure the inner ring 22 on each of the journals 14, and the outer circumferential surface 16 is guided by the raceway surface 9 or fixed by the raceway surface 9 (for example, with respect to the circumferential directions 7, 8 and the radial direction 12 around the first rotation axis 5). [Explanation of symbols]

[0117] 1. Triple-type joint 2. Outer joint section 3. Inner joint section 4. Rotating bodies 5. First rotation axis 6 Receptor part 7. First circumferential direction 8. Second circumferential direction 9 Raceway surface 10. Second rotation axis 11 Centrosome 12 Radial 13 Journal axis 14 Journals 15 Inner surface 16 Outer surface 17 First contact surface 18. Second contact surface 19. First pitch circle radius 20 Second pitch circle radius 21 Third pitch circle radius 22 Inner Ring 23 Outer ring 24 Rolling elements 25 angular area 26 Side Shaft 27 Automobiles 28 Drive Unit 29 joints 30 wheels 31 Torque 32 offset 33 Bending angle 34 ACFG value 35 Trends 36 Maximum value 37 Rotation axis 38 gears 39 Central area 40 outer area 41 Central section 42 Center of mass 43. First thickness 44 First surface 45 Second thickness 46 Second surface

Claims

1. A tripod-type joint (1) comprising at least an outer joint portion (2), an inner joint portion (3), and a plurality of rotating bodies (4), The aforementioned outer joint portion (2) is A receiving portion (6) for the inner joint portion (3) extends along the first rotation axis (5), Three orbital surfaces (9) extending along the first rotation axis (5) and distributed in the circumferential direction (7, 8) and It has, The aforementioned inner joint portion (3) is A central body (11) extending along the second axis of rotation (10), Three journals (14) extending from the central body (11) along the radial direction (12) and It has, Each of the journals has a journal axis (13) and is distributed in the circumferential direction (7, 8). One of the plurality of rotating bodies (4) is positioned in each of the journals (14), The rotating body (4) contacts the journal (14) with its inner circumferential surface (15) and contacts the respective raceway surfaces (9) with its outer circumferential surface (16). Each journal (14) has contact surfaces (17, 18) for contacting the inner circumferential surface (15), The first contact surface (17) is oriented at least in the first circumferential direction (7), The second contact surface (18) is oriented at least in the second circumferential direction (8), The second circumferential direction (8) is oriented in the opposite direction to the first circumferential direction (7). When the aforementioned rotating shafts (5, 10) are arranged coaxially with respect to each other, The first contact surface (17) has a first pitch circle radius (19), The second contact surface (18) has a second pitch circle radius (20), The aforementioned raceway surface (9) has a third pitch circle radius (21), At least the first pitch circle radius (19) and the second pitch circle radius (20) have different values ​​from each other. Tripod-type joint (1).

2. A tripod-type joint (1) according to claim 1, The first pitch circle radius (19) is either smaller than or larger than the third pitch circle radius (21). A tripod-type joint (1) characterized by the following:

3. A tripod-type joint (1) according to claim 1 or 2, The second pitch circle radius (20) is either greater than or less than the third pitch circle radius (21). A tripod-type joint (1) characterized by the following:

4. A tripod-type joint (1) according to claim 1 or 2, The value of the first pitch circle radius (19) or the second pitch circle radius (20) corresponds to the value of the third pitch circle radius (21). A tripod-type joint (1) characterized by the following:

5. A tripod-type joint (1) according to claim 1, The third pitch circle radius (21) is either greater than or less than the first pitch circle radius (19) and the second pitch circle radius (20). A tripod-type joint (1) characterized by the following:

6. A tripod-type joint (1) according to claim 1 or 2, Each of the rotating bodies (4) is: The inner ring (22) having the inner circumferential surface (15), The outer ring (23) having the outer peripheral surface (16), A plurality of rolling elements (24) are located between the inner ring (22) and the outer ring (23). Equipped with A tripod-type joint (1) characterized by the following:

7. A tripod-type joint (1) according to claim 1 or 2, The outer circumferential surface (16) has a convex shape relative to each of the raceway surfaces (9). A tripod-type joint (1) characterized by the following:

8. A tripod-type joint (1) according to claim 1 or 2, The inner circumferential surface (15) is cylindrical. A tripod-type joint (1) characterized by the following:

9. A tripod-type joint (1) according to claim 1 or 2, The inner circumferential surface (15) is concave with respect to each of the contact surfaces (17, 18). A tripod-type joint (1) characterized by the following:

10. A tripod-type joint (1) according to claim 1 or 2, Each of the aforementioned contact surfaces (17, 18) extends over an angular range (25) that spreads out from each of the journal axes (13), The aforementioned angular range (25) includes angles less than 180 degrees. A tripod-type joint (1) characterized by the following:

11. An inner joint portion (3) for a tripod-type joint (1), A central body (11) extending along the second axis of rotation (10), Three journals (14) extending from the central body (11) along the radial direction (12) and It has at least the following features: Each of the journals (14) has a journal axis (13) and is distributed in a circumferential direction (7, 8). Each of the journals (14) has a contact surface (17, 18) for contacting a rotating body (4) of the tripod-type joint (1) that can be placed in the journal (14), The first contact surface (17) is oriented at least in the first circumferential direction (7), The second contact surface (18) is oriented at least in the second circumferential direction (8), The second circumferential direction (8) is oriented in the opposite direction to the first circumferential direction (7). The first contact surface (17) has a first pitch circle radius (19), The second contact surface (18) has a second pitch circle radius (20), The first pitch circle radius (19) and the second pitch circle radius (20) have different values ​​from each other. Inner joint section (3).

Images