Sliding type constant velocity joint and method for manufacturing sliding type constant velocity joint

Abstract

To provide a sliding type constant velocity joint that can be efficiently manufactured and has a preferable characteristic relating to amplitude behavior or a long life.SOLUTION: A sliding type constant velocity joint is manufactured so that an outer annular line (RL11) passing through all the ball center points in an outer ball raceway (18) has an irregular shape having a maximum outer annular line diameter and a minimum outer annular line diameter and an inner annular line (RL12) passing through all the ball center points in an inner ball raceway (20) has a non-circular shape having a maximum inner annular line diameter and a minimum inner annular line diameter, where a joint inner part (12) is fitted so that an angle (α) formed between the maximum inner annular line diameter (DImax) and the maximum outer annular line diameter (DOmax) becomes less than 30° relative to a joint outer part (11).SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present invention relates to a sliding constant velocity joint and a method for manufacturing the same, which is designed to simultaneously variable and slidably transmit torque between an outer joint part and an inner joint part.

[0002] German Patent Application No. DE 10 2005 063 006 A1 discloses an inner joint part for a sliding constant velocity joint, which has a spherical outer guide surface for guiding a ball cage and a plurality of ball tracks distributed around the periphery of the spherical guide surface for accommodating torque-transmitting balls. Each of the ball tracks has a first, hard-machined raceway section for guiding the balls and a second, non-mechanically machined raceway section that does not perform any guiding function for the balls.

[0003] WO 2018 / 072835 discloses a method for machining ball tracks and guide webs of an inner joint part for a constant velocity joint in one clamping operation. This involves mechanical machining of at least one first ball track in a first rotational position followed by rotation to a second rotational position for machining at least one further ball track of the inner joint part. The method provides for mechanical machining of at least one guide web during rotation of the inner joint part from the first rotational position to the second rotational position.

[0004] JP 11-13780 A discloses a ball joint having an outer joint part and an inner joint part. The inner joint part is forged from a blank and heat treated, with the shape of the ball raceway remaining as forged. The dimensions of the ball raceway are measured to divide the inner joint part into three groups according to their dimensions. The outer joint part is also forged, heat treated, and finish-machined. After heat treatment, the ball raceway of the outer joint part is finish-machined by grinding.

[0005] JP 2005-337290 A discloses a drive shaft with a double offset joint on one side and an undercut-free ball joint on the other side. The running play of the ball joint is in the range of 20 to 200 micrometers. The pitch circle diameters (PCDs) of the ball raceways of the outer and inner rings are measured and classified according to a bandwidth of approximately 20 micrometers. Combinations of multiple outer and inner rings result in running play of approximately 20 to 60 micrometers for ball joints and 20 micrometers for double offset joints. An allocation process is performed to determine the outer and inner rings to be paired so that the distance between them is approximately 80 micrometers. The ball raceways of the inner and outer rings are finish-machined by cold forging.

[0006] The present invention is based on the problem of proposing a sliding constant velocity joint that can be efficiently manufactured and has good properties in terms of amplitude behavior (noise, vibration, harshness, also abbreviated as "NVH") or a long service life, and a further problem of proposing an efficient method for manufacturing such a sliding constant velocity joint.

[0007] According to the present invention, there is provided a sliding constant velocity joint, comprising: a joint outer part having an outer part longitudinal axis and outer ball raceways distributed over a circumferential surface, at least a partial section of which is hardened and mechanically finished before hardening, i.e., not mechanically processed after hardening; a joint inner part having a spherical outer guide surface and a plurality of inner ball raceways distributed over a circumferential surface, at least a partial section of which is hardened and processed by cutting; balls arranged in raceway pairs, each consisting of one outer ball raceway and one inner ball raceway; and a ball cage arranged between the joint outer part and the joint inner part, having a cage inner surface, a cage outer surface, and cage windows distributed over a circumferential surface, each accommodating at least one of the balls, wherein an outer annular line passing through the ball centers of all the balls in a cross section passing through the extended joint near the balls in contact with the outer ball raceway has a maximum an inner ball of the joint inner portion having an irregular shape with an outer annular diameter (DOmax) and a minimum outer annular diameter (DOmin), the maximum outer annular diameter (DOmax) being greater than the minimum outer annular diameter (DOmin) by an outer diameter difference value (DOdiff) of at least 0.15%, and a mean outer annular diameter (DOmid) being defined as half the sum of the maximum outer annular diameter (DOmax) and the minimum outer annular diameter (DOmin), i.e., DOmid=(DOmax+DOmin) / 2; The raceways are manufactured so that, in a cross section through an elongated joint by the ball in contact with the inner ball raceway, an inner annular line passing through all ball center points of the ball has a non-circular shape having a maximum inner annular line diameter (DImax) and a minimum inner annular line diameter (DImin), the maximum inner annular line diameter (DImax) being greater than the sum of the mean outer annular line diameter (DOmid) and 0.25 times an outer diameter difference value (DOdiff), and the minimum inner annular line diameter (DImin) being greater than the mean outer annular line diameter (DOmid) and 0.A sliding constant velocity joint is proposed in which the difference between the outer diameter difference (DOdiff) is less than 25 times, and the inner joint part is mounted relative to the outer joint part such that the angle formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) is less than 30°.

[0008] The advantages of the sliding constant velocity joint according to the present invention, also referred to as sliding joint or joint for short, are that it has a long service life and good properties in terms of noise, vibration, and harshness (NVH) behavior, while being easy to manufacture. When hardening the joint parts, especially the outer joint part of a sliding joint, it can lead to undesirable hardening distortions due to its relatively long and thin wall relative to the part diameter. These hardening distortions can only be reduced to a certain extent by process technology, which can result in different ball play in each raceway pair over the circumference, which can lead to impairments in terms of service life or NVH properties. In the case of an outer joint part with a very irregular annular line, an inner joint part that is geometrically approximated to this is manufactured and attached to the joint. Here, the maximum outer annular line diameter (DOmax) of the outer joint part may be greater than its minimum diameter (DOmin) by more than 0.15%, more than 0.2%, or more than 0.25%, and may be smaller by, for example, less than 2.0%, less than 1.5%, or less than 1.0%. The inner joint part or its ball track is intentionally manufactured non-circular and is aligned with the manufactured non-circular shape of the outer joint part so that the angle formed between the maximum inner annular diameter of the inner joint part and the maximum outer annular diameter of the outer joint part is less than 30°. Overall, this results in a reduction of the maximum ball play in the associated ball track, which has a favorable effect on the amplitude behavior and service life of the joint.

[0009] The outer and / or inner annular lines are preferably formed so as to extend continuously or steplessly around the circumference. The cross section through the extended joint used to define the outer or inner annular line may lie within a range of ±10 mm around the main working range of the joint, in particular the axis of the outer ball raceway. To facilitate installation, the inner and / or outer joint parts may be provided with markings indicating the associated maximum or minimum annular line diameter.

[0010] According to one embodiment, the maximum inner annular diameter (DImax) may be equal to the mean outer annular diameter (DOmid) plus 0.4 to 0.6 times the outer diameter difference value (DOdiff). Alternatively or additionally, the minimum inner annular diameter (DImin) may be equal to the difference between the mean outer annular diameter (DOmid) and 0.4 to 0.6 times the outer diameter difference value (DOdiff).

[0011] The number of ball tracks or balls in the joint can be selected according to technical requirements. Typically, joints with six or eight balls are used in automotive drivetrains, although joints with other numbers of balls or tracks are also used. A pitch angle is formed between two circumferentially adjacent balls. According to more specific embodiments, the angle formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) may be smaller than the pitch angle.

[0012] The joint outer part has a radial wall thickness in a longitudinal section through the raceway bottom, with the ratio of the radial wall thickness to the mean outer annular diameter (DOmid) preferably being less than or equal to 0.075. The inner surface of the joint outer part, on which the outer ball raceway is formed radially outward, may be machined, which allows for easy production with high precision to the desired manufacturing tolerances. The outer ball raceway may be mechanically finish-machined before hardening, either without chipping, particularly by forging, or with chipping, particularly by milling.

[0013] The spherical outer guide surface of the joint inner part is ideally round in a cross section through the joint inner part, i.e., manufactured with a manufacturing tolerance of, in particular, plus or minus 0.03 mm with respect to the nominal outer diameter. Preferably, the spherical outer guide surface is hardened at least in a section and machined after hardening. The ball raceway of the joint inner part can be machined before hardening and / or after hardening, at least in its functional section. Machining the ball raceway before hardening leads to particularly efficient manufacturing. Machining the ball raceway after hardening leads to high process reliability or high finishing accuracy. Preferably, the ball raceway is manufactured with a manufacturing tolerance of less than plus or minus 0.1 mm, in particular less than plus or minus 0.03 mm. Machining to produce the desired high finishing accuracy can be carried out, for example, by grinding.

[0014] According to one embodiment, at least the peripheral surface of the ball cage is ideally round, i.e., manufactured with a manufacturing tolerance of plus or minus 0.03 mm relative to the nominal circular peripheral diameter. The ball cage can have a curved, spherical outer control surface and an outer free surface about a first center point (MK1) and a spherical inner control surface about a second center point (MK2), the first center point (MK1) and the second center point (MK2) being axially spaced from the window or ball center plane (EK) of the ball cage, respectively. Between the spherical inner control surface and the outer free surface, the ball cage has a minimum radial wall thickness, and the ratio of the minimum radial wall thickness to the pitch circle diameter (PCD) can be, for example, less than 0.08.

[0015] According to one embodiment, the balls can be manufactured with a manufacturing tolerance of less than plus or minus 4 micrometers on the ball nominal diameter, which provides a high degree of precision such that sorting of balls according to their dimensions for individual ball tracks is not necessary.

[0016] The sliding joint may be designed, for example, such that the inner joint part can be bent relative to the outer joint part by a bending angle of up to 20°. Furthermore, the sliding constant velocity joint may be designed as a double offset joint, in which case other joint types such as VL or XL joints are also possible.

[0017] In the assembled state, a joint center plane (EM) is defined under the stretched joint, and the outer ball tracks have a central working section around the joint center plane and bottom-side and top-side secondary sections that lead from the central working section to the bottom and joint opening. The outer ball tracks may be slightly widened in the bottom-side secondary track section and / or the top-side secondary track section relative to the central working section, for example by at least 0.1 mm.

[0018] The subject matter also relates to a method for manufacturing a sliding constant velocity joint, comprising the steps of manufacturing a joint outer part having a longitudinal axis, a connection side, an opening side, an inner surface, and an outer ball raceway, the outer ball raceway being soft-finished and subsequently hardened, i.e., remaining unmechanically processed after hardening, wherein, in a cross section through the joint outer part, the ball contact points of the outer ball raceway define an irregularly shaped outer annular line having a maximum outer annular line diameter (DOmax) and a minimum outer annular line diameter (DOmin), the maximum outer annular line diameter (DOmax) being greater than the minimum outer annular line diameter (DOmin) by an outer diameter difference value (DOdiff) of at least 0.15%, 0.2%, or 0.25%, and wherein the mean outer annular line diameter (DOmid) is greater than the maximum outer annular line diameter (DOmax) and the minimum outer annular line diameter (DOmid). and manufacturing a joint inner part having a longitudinal axis, an outer surface, and an inner ball raceway, the inner ball raceway being soft pre-machined, hardened, and finish-machined such that, when viewed in a cross section through the joint inner part, ball contact points of the inner ball raceway define an inner annular line having a non-circular shape with a maximum inner annular line diameter (DImax) and a minimum inner annular line diameter (DImin), whereby the maximum inner annular line diameter (DImax) is greater than the sum of the average outer annular line diameter (DOmid) and 0.25 times an outer diameter difference value (DOdiff), and the minimum inner annular line diameter (DImin) is greater than the sum of the average outer annular line diameter (DOmid) and 0.25 times an outer diameter difference value (DOdiff), and the minimum inner annular line diameter (DImin) is greater than the sum of the average outer annular line diameter (DOmid) and 0.The problem is solved by a method including the steps of: manufacturing a ball cage having a cage axis, a cage inner surface, a cage outer surface, and cage windows distributed circumferentially around the cage axis (A13); inserting the joint inner part into the ball cage; inserting the joint inner part with the ball cage into the joint outer part, whereby the angle formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) is less than 30°; and inserting balls into the cage windows, where each ball is accommodated in a raceway pair consisting of one outer ball raceway and one inner ball raceway.

[0019] The method according to the invention achieves the same advantages as the product described above, so reference is made to the above description. It will be understood that all the features mentioned in relation to the joint according to the invention are also transferable to the present method, and vice versa. The present method provides an efficient finish, since a post-hardening machining step is omitted when manufacturing the outer part of the joint, and any non-circular shape resulting from hardening distortions is compensated for by the intended non-circular finish of the inner part of the joint. Overall, this results in a joint that is easy and cheap to manufacture, has a long service life, and has good properties in terms of noise, vibration, and harshness behavior ("NVH").

[0020] Advantageous embodiments are explained below on the basis of the drawings. [Brief explanation of the drawings]

[0021] [Figure 1A] 1 is a cross-sectional view showing a sliding type constant velocity joint according to the present invention. [Figure 1B] 1B is a longitudinal cross-sectional view of a sliding constant velocity joint taken along the section line 1B-1B of FIG. 1A and passing through a ball plane. [Figure 1C] 1C is a longitudinal cross-sectional view of a sliding constant velocity joint through a web plane along section line 1C-1C of FIG. 1A. [Figure 1D] 1B shows a detail in cross section through the ball track of the outer part of the joint with the ball housed therein according to FIG. 1A; FIG. [Figure 2A] 1B is an enlarged view of the outer portion of the joint of FIG. 1A with the dimensions indicated. [Figure 2B] 1B is an enlarged view of the inner portion of the joint of FIG. 1A with the dimensions indicated. [Figure 3A] FIG. 1B is a perspective view showing the inner part of the joint of FIG. 1A. [Figure 3B] 1A or 3A in an axial view of the inner part of the joint. FIG. [Figure 3C] 3C is a view showing the inner portion of the joint along section line 3C-3C of FIG. 3B. [Figure 3D] FIG. 10 shows a detail in cross section through the ball track of the inner part of the joint with the ball housed therein. [Figure 4A] FIG. 1B is a perspective cross-sectional view showing the outer portion of the joint of FIG. 1A. [Figure 4B] FIG. 4B is a half-longitudinal cross-sectional view showing the outer portion of the joint of FIG. 1A or FIG. 4A. [Figure 5A] FIG. 1B is a perspective view showing the ball cage of FIG. 1A. [Figure 5B] 1A or 5A in a longitudinal cross section through two opposing web regions. FIG. [Figure 5C] 1A or 5A in a longitudinal cross section through two opposing window areas. FIG.

[0022] 1A-1D (collectively also referred to as FIG. 1) show a sliding constant velocity joint 10 according to the present invention having an outer joint part 11, an inner joint part 12, a ball cage 13, and torque-transmitting balls 14 held in a common ball plane EK within windows 15 of the ball cage 13.

[0023] The joint outer part 11 has an inner guide surface 16 which contacts a particularly spherical control surface 17 of the ball cage 13 and can be guided in this guide surface 16. Furthermore, the joint outer part 11 has an outer part longitudinal axis A11 and a number of outer ball tracks 18 which are distributed over the periphery and extend longitudinally, and which extend over the majority of the joint outer part 11 to an open end or opening 19. Each track pair formed by an inner ball track 20 of the joint inner part 12 and an outer ball track 18 of the joint outer part 11 guides one of the torque-transmitting balls 14. Here, the windows 15 of the ball cage 13 or the balls 14 accommodated therein together define a ball plane EK. During joint bending, the ball plane EK is a plane which bisects the angle between the joint outer part 11 and the joint inner part 12. At the end 21 opposite the opening 19, the joint outer part 11 is closed in a bell-like shape and has a base 23 with an integrally formed pivot 24 used for torque transmission.

[0024] The joint outer part 11 is manufactured in such a way that the outer ball raceway 18 is finish-machined and then at least a section of the outer ball raceway 18 is hardened. This means that the outer ball raceway 18 retains its final profile before hardening and remains unmechanically machined after hardening. The inner surface 16 of the joint outer part 11, on which the outer ball raceway 18 is shaped radially outward, may be machined. This allows for easy production with the desired manufacturing tolerances. The outer ball raceway 18 may be mechanically finish-machined before hardening, either without chips, in particular by forging, or with chips, in particular by milling.

[0025] Subsequent hardening results in hardening strains in the outer joint part 18. These hardening strains lead to different radii of the outer joint part 11 around its circumference, or to different radii between the ball center points and the longitudinal axes A11 of the balls 14 housed within the ball raceways 18. In the hardened state, as shown in FIG. 1A or 2A, the centers of all the balls 14 in a cross section through the stretched joint define an outer annular line RL11 when the balls 14 are in contact with the outer ball raceway 18, as shown in FIG. 1D. This outer annular line RL11, passing through all the ball center points, has an irregular shape with a maximum outer annular line diameter DOmax and a minimum outer annular line diameter DOmin, as can be seen in FIG. 2A. In the simplified example shown here, the outer annular line RL11 has an elliptical shape symmetrical about its axis. It will be understood that the outer joint part 11 can have a different shape in practice, particularly an asymmetric shape. For example, the ball trajectory 18 may describe any other irregular circular line shape, such as a polygonal or wavy circular line RL11 having irregular maxima and minima around its circumference.

[0026] As can be seen from FIG. 1D, the outer ball tracks 18 are preferably designed in this embodiment so that, in cross section, two points of contact are formed with the associated torque-transmitting balls 14. The two-point contact can be formed, for example, by a track shape that is gothic or elliptical in cross section. The radial plane ER passing through the ball center points and the lines passing through the contact points 22, 22' respectively form angles γ22, γ22', which can be, for example, between 30° and 50°. The two-point contact or two-point track allows for a self-centering measurement of the ball tracks 18. However, circular tracks can also be used in principle.

[0027] Regardless of this shape, the individually determined ball center points M14 of the balls 14 can be connected to the outer annular line RL11 in such a way that the annular line preferably has a continuous or stepless extension over the circumference. The same also applies to the inner annular line RL12 of the joint inner part 12, which will be explained in more detail below. The cross sections through the extended sliding constant velocity joint 10 used to define the outer and / or inner annular lines can lie within the main working range of the joint, in particular within a range of plus / minus 10 mm around the axis M18 of the outer ball raceway 18.

[0028] The joint outer part 11 is made non-circular by a contouring finishing process before and subsequently during hardening, in which case the maximum outer annular diameter DOmax is at least 0.15% greater than the minimum outer annular diameter DOmin, i.e. DOmax ≥ 1.0015 * DOmin. It should be understood that larger difference ratios DOmax / DOmin are also possible, for example at least 1.025, at least 1.004, or at least 1.005. In the case of joint types with an ideally round target pitch circle diameter PCDsoll (English "Pitch Circle Diameter") of the ball 14, the minimum outer annular diameter DOmin can be, for example, between PCDsoll - (0.5% x PCDsoll) and PCDsoll - (1.0% x PCDsoll). That is, (PCDsoll-1.0% x PCDsoll) <DOmin<(PCDsoll-0.5%×PCDsoll) is.

[0029] Correspondingly, the maximum outer ring diameter DOmax can be, for example, between PCDsoll + (0.5% x PCDsoll) and PCDsoll + (1.0% x PCDsoll). (PCDsoll + 0.5% × PCDsoll) <DOmax<(PCDsoll+1.0%×PCDsoll) is.

[0030] From the values ​​found for DOmax and DOmin, the difference value DOdiff and the mean outer annular diameter DOmid can be calculated: DOdiff = DOmax - DOmin DOmid=(DOmax+DOmin) / 2 is.

[0031] The mean outer annular diameter DOmid is shown by the dashed line in Figure 2A.

[0032] To compensate for the hardening distortions of the outer joint part 11, the inner joint part 12 is manufactured by pre-machining the inner ball raceways 20, which are distributed around the periphery, with a certain degree of tolerance, followed by hardening at least a portion of the inner ball raceways 20 and then finishing them to the desired geometric shape. However, it is also possible to soft-finish the inner joint part and not perform any further mechanical processing after hardening. The ball raceways 20 of the inner joint part 12 are machined so that, in a cross section through the extended joint near the balls in contact with the inner ball raceways, the inner annular line RL12 passing through the ball centers M14 of all balls 14 has a non-circular shape with a maximum inner annular line diameter DImax and a minimum inner annular line diameter DImin. By machining the ball raceways 20, a high finishing accuracy of a few micrometers can be achieved.

[0033] Here, the target geometry for manufacturing the ball track 20 of the inner joint part 12 can be derived from the above-mentioned values ​​of the outer joint part 11. That is, the inner joint part 12 is manufactured so as to deviate from a symmetrical round shape. The arrangement and geometry of the ball track, and thereby a non-circular, in particular elliptical, shape with maximum and minimum diameters relative to the ball center point defined at ball contact, is generated.

[0034] Specifically, the inner ball raceway 20 is configured such that the maximum inner annular diameter DImax is greater than the sum of the average outer annular diameter DOmid and 0.25 times the outer diameter difference value DOdiff and / or is smaller than the maximum outer annular diameter DOmax, i.e.: DImax > DOmid + 0.25 × DOdiff and / or DImax <DOmax The metal can be machined to a finish such that

[0035] The minimum inner annular diameter DImin is at least one of: smaller than the minimum outer annular diameter DOmin; smaller than the difference between the average outer annular diameter DOmid and 0.25 times the outer diameter difference value DOdiff; and / or larger than the difference between the average outer annular diameter DOmid and 0.75 times the outer diameter difference value DOdiff, i.e.: DImin <DOmin、 DImin <DOmid-0.25×DOdiffおよび / または DImin>DOmid-0.75×DOdiff is.

[0036] In the case of a joint type where the ideal pitch circle diameter (English: "Pitch Circle Diameter", PCD) of the ball 14 is 60.00 mm, the minimum outer annular line diameter Domin can exist, for example, between 59.04 mm and 59.07 mm, and the maximum outer annular line diameter D0max can exist, for example, between 60.03 mm and 60.06 mm. Exemplarily, if the value of 59.04 mm is taken for D0min and the value of 60.06 mm is taken for D0max, it has been found that Dodiff = 1.02 mm and D0mid = 59.55 mm. From this result, the annular line RL12 of the joint inner part 12 can be obtained, or the corresponding contour of the inner ball track 20 for generating the annular line RL12 can be obtained. Here, the maximum inner annular line diameter DImax of the annular line RL12 of the joint inner part 12 is particularly larger than 59.80 mm and smaller than the maximum outer annular line diameter D0max. That is, 59.8 mm < DImax < 60.06 mm. The minimum inner annular line diameter DImin of the annular line RL12 is particularly smaller than 59.29 mm, or smaller than 59.04 mm, or larger than 58.78 mm, that is: 59.04 mm > DImin > 58.78 mm It should be understood that these data are only exemplary means.

[0037] In a further embodiment, the joint inner part 12 can be manufactured such that the maximum inner annular line diameter DImax is equal to the sum of the average outer annular line diameter D0mid and 0.4 to 0.6 times the outer diameter difference value D0diff, and / or the minimum inner annular line diameter DImin is equal to the difference between the average outer annular line diameter D0mid and 0.4 to 0.6 times the outer diameter difference value D0diff.

[0038] The joint inner part 12 thus produced is then mounted relative to the joint outer part 11 such that the angle formed between the maximum inner annular diameter DImax and the maximum outer annular diameter DOmax is less than 30°. To facilitate mounting, the joint inner part 12 and / or the joint outer part 12 can be provided with markings 44 indicating the associated maximum or minimum annular diameter. By aligning the mounting of the joint inner part 12 relative to the joint outer part 11 with respect to the angular position, a reduction in the maximum ball play of the balls 14 in the associated outer and inner ball tracks 18, 20 is achieved, which has a favorable effect on the vibration behavior and long life of the joint.

[0039] In this example, each raceway pair, formed by an outer ball raceway 18 and an inner ball raceway 20, lies with its raceway centerline in a radial plane passing through the joint. These radial planes are each equiangularly spaced from one another in this example; however, joints with unequal pitch angles, such as so-called "twin ball" joints, are also possible. The number of torque-transmitting balls 14 and the corresponding outer and inner ball raceways 18, 20 is eight in this example, but this number need not be limited to this. A pitch angle is formed between two circumferentially adjacent balls 14. According to a more specific embodiment, the angle formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) may be less than the minimum pitch angle.

[0040] Details of the joint inner part 12 are shown in Figures 3A to 3D, also collectively referred to as Figure 3. The spherical outer guide surface 26 of the joint inner part 12 is ideally round in a cross section through the joint inner part, i.e., manufactured with a manufacturing tolerance of, in particular, plus or minus 0.03 mm with respect to the nominal outer diameter. Preferably, the spherical outer guide surface 26 is hardened and machined after hardening, at least in the section that comes into contact with the inner guide surface 16 of the joint outer part 11 during operation of the joint.

[0041] In this embodiment, the ball tracks 20 of the joint inner part 12 each have a first track section 28, along which the ball 14 is guided during operation, and a second track section 29, which does not perform any guiding function for the ball. The ball tracks 20 are machined after hardening in the first track section 28, which may also be called the functional section. Preferably, these ball tracks are manufactured with a manufacturing tolerance of less than plus / minus 0.1 mm, in this case, less than plus / minus 0.03 mm. Machining to achieve the desired high finish accuracy can be carried out, for example, by means of grinding.

[0042] The second raceway section 29 is formed deeper than the first raceway section 28 (as viewed in a longitudinal cross section through the raceway bottom, as shown in FIG. 3B ). Thus, the second raceway section 29 thus formed forms a tool passage for hardening the first raceway section 28. A step 30 may be formed between the first raceway section 28 and the second raceway section 29. In this example, the first raceway section 28 has a longer length than the second raceway section 29.

[0043] The joint inner part 12 can be manufactured, for example, by preforming or forging a blank into a preformed part having an outer surface with a circumferentially distributed ball raceway 20, a central through-opening 31, a first end face 32, and an oppositely oriented second end face 33. The raceways of the preformed blank can then already have a first raceway segment 28 with a smaller raceway cross-sectional geometry and a second raceway segment 29 with a larger raceway cross-sectional geometry. The preformed blank can then be hardened at least in the first raceway segment 28, while the second raceway segment 29 can remain unhardened. The first raceway segment 28 is then machined to the desired geometry, while the second raceway segment 29 can remain unmachined.

[0044] As can be seen from Figure 3D, in this embodiment, the inner ball tracks 20 are also preferably designed in cross section so that two-point contact is formed with the associated balls 14. The contact points 36, 36' respectively include angles γ36, γ36' with the radial plane ER. Alternatively, circular tracks can be used.

[0045] The balls 14 can be manufactured with a manufacturing tolerance of less than plus or minus 4 micrometers about the ball nominal diameter, which provides such precision that sorting of the balls 14 according to their dimensions for the individual ball tracks 18, 20 is not necessary.

[0046] 4A and 4B show the outer joint part 11 in detail. The outer joint part 11 has a sleeve or wall section 25, into which the ball track 18 is molded. In a longitudinal section through the track bottom of the ball track 18, the wall section 25 has a radial thickness T25. The ratio of this radial wall thickness T25 to the mean outer annular diameter DOmid may be, for example, 0.075 or less. At the open end of the ball track 18, a stop means 38 is provided to prevent the balls 14 from undesirably slipping out of the ball track. The stop means 38 may be designed as a deformation area or a molded protrusion.

[0047] 5A to 5C show the details of the ball cage 15. The ball cage 13 is designed annularly about the cage axis A13 and has a curved outer control surface 17 followed by a conical free surface 34 that connects substantially tangentially to the control surface 17. Inside the ball cage 13, the ball cage 13 forms a concave inner control surface 35 for guiding the ball cage 13 relative to the outer guide surface 26 of the joint inner part 12. The outer control surface 17 has a maximum outer diameter centered on a first center point MK1, which is located at an approximately equal axial distance from the window or ball plane EK in the opposite direction to the maximum inner diameter of the inner control surface 35, which has a center point MK2. This deviation ("offset") of the maximum diameters of the control surfaces gives the joint its name, specifically a double offset joint.

[0048] In this embodiment, at least the peripheral surface part of the ball cage 13 is preferably ideally round, i.e. manufactured with a manufacturing tolerance of plus / minus 0.03 mm, in particular with respect to the nominal peripheral diameter. Between the inner control surface 35 and the outer free surface 34, the ball cage 13 has a minimum radial wall thickness. The ratio of the minimum radial wall thickness to the pitch circle diameter (PCD) may be, for example, less than 0.08.

[0049] In this embodiment, the sliding constant velocity joint 10 is designed so that the inner joint part 12 can be bent relative to the outer joint part 11 by a bending angle b of up to 20°. As shown in FIGS. 1B and 1C, a joint center plane EM is defined with the joint extended in the assembled state. The outer ball raceway 18 can have a central working section 37m around the joint center plane EM and bottom-side and opening-side secondary raceway sections 37b, 37o that lead from the central working section 37m to the bottom 23 and opening 19. The outer ball raceway 18 can optionally be slightly widened, for example by at least 0.1 mm, in the bottom-side secondary raceway section 37b and / or the opening-side secondary raceway section 37o relative to the central working section 37m. 1B and 1C also show a drive shaft 39, which is inserted in a rotationally immobile manner into the shaft groove of the inner joint part 12 and is axially held therein by means of a retaining ring 40. Furthermore, a bellows 41 is provided, the large flange 42 of which is tightly connected to the outer joint part 11 by means of a corresponding fixing ring, and the small flange 43 of which is tightly connected to the drive shaft 39 by means of a corresponding fixing ring.

[0050] As already mentioned above, the joint is designed as a double offset joint, but is not limited to this. Other joint types, such as VL or XL joints, can also be constructed in accordance with the invention with an outer joint part and an inner joint part having a deliberately non-circular and mutually aligned shape.

[0051] The sliding constant velocity joint 10 according to the present invention has the advantages of being easy to manufacture, having a long lifespan and good properties in terms of noise, vibration and harshness behavior ("NVH"). [Explanation of symbols]

[0052] 10. Sliding constant velocity joint 11 Outer part of the joint 12 Inner part of the joint 13 Ball Cage 14 balls 15. Window 16 Inner guide surface (11) 17 Outer control surface (13) 18 Outer ball trajectory 19 Opening 20 Inner ball trajectory 21 End 22,22' Contact 23 Bottom 24 Pivot 25 Wall section 26 Guide surface (12) 27 Functional classification 28 First orbital segment 29 Second orbital segment 30 Steps 31 Opening 32 first end face 33 Second end face 34 Free surface 35 Inner control surface (13) 36,36' Contact point 37m track division 37o,37b Orbit division 38 Stopper means 39 Drive shaft 40 retaining ring 41 Bellows 42 flange 43 flange 44 Marking α angle β Pitch angle γ contact angle δ bending angle A axis D14 ball diameter DImax Maximum inner annular diameter DImid Mean inner annular diameter DImin Minimum inner annular diameter DOdiff Outer diameter difference DOmax Maximum outer ring wire diameter DOmid Average outer ring diameter DOmin Minimum outer annular diameter EK Ball Plane EM center plane ER radial plane M14 ball center point M18 orbit center MK1 First Center Point MK2 Second Center Point PCD Pitch Circle Diameter RL Loop Line T Thickness

Claims

1. A sliding type constant velocity joint, a joint outer part (11) having an outer part longitudinal axis (A11) and outer ball tracks (18) distributed over its periphery, at least a section of which is hardened, and which has been mechanically finished before hardening, i.e. which is not mechanically worked after hardening; a joint inner part (12) having a spherical outer guide surface (26) and a plurality of inner ball tracks (20) distributed around its periphery, at least a portion of the inner ball tracks (20) being hardened; balls (14) arranged in pairs of tracks, each consisting of an outer ball track (18) and an inner ball track (20); a ball cage (13) disposed between the joint outer part (11) and the joint inner part (12), having a cage inner surface, a cage outer surface, and cage windows (15) distributed around the periphery, each of which accommodates at least one of the balls (14); In a cross section passing through an elongated joint beside the ball (14) in contact with the outer ball raceway (18), an outer annular line (RL11) passing through all ball center points (M14) of the ball (14) has an irregular shape having a maximum outer annular line diameter (DOmax) and a minimum outer annular line diameter (DOmin); - the maximum outer annular diameter (DOmax) is greater than the minimum outer annular diameter (DOmin) by an outer diameter difference value (DOdiff) of at least 0.15%; the mean outer annular diameter (DOmid) is defined as half the sum of the maximum outer annular diameter (DOmax) and the minimum outer annular diameter (DOmin) [DOmid=(DOmax+DOmin) / 2]; the inner ball raceway (20) of the joint inner part (12) is manufactured so that, in a cross section passing through the stretched joint beside the balls (14) in contact with the inner ball raceway (20), an inner annular line (RL12) passing through all ball centre points (M14) of the balls (14) has a non-circular shape with a maximum inner annular line diameter (DImax) and a minimum inner annular line diameter (DImin); the maximum inner annular diameter (DImax) is greater than the mean outer annular diameter (DOmid) plus 0.25 times the outer diameter difference value (DOdiff); the minimum inner annular diameter (DImin) is less than the difference between the mean outer annular diameter (DOmid) and 0.25 times the outer diameter difference value (DOdiff); The inner joint part (12) is mounted relative to the outer joint part (11) such that the angle (α) formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) is less than 30°.

2. 2. The sliding type constant velocity joint according to claim 1, wherein the outer annular line (RL11) and / or the inner annular line (RL12) extend continuously.

3. 3. The sliding constant velocity joint according to claim 1 or 2, wherein the cross section through the stretched joint is in the main working range of the joint, i.e. within a range of plus / minus 10 mm around the axis (M18) of the outer ball raceway (18).

4. the maximum inner annular diameter (DImax) is equal to the mean outer annular diameter (DOmid) plus 0.4 to 0.6 times the outer diameter difference (DOdiff); 3. The sliding type constant velocity joint according to claim 1, wherein the minimum inner annular diameter (DImin) is equal to the difference between the average outer annular diameter (DOmid) and 0.4 to 0.6 times the outer diameter difference value (DOdiff).

5. 3. The sliding-type constant velocity joint according to claim 1, wherein a pitch angle (β) is formed between two adjacent balls (14) in the circumferential direction, and an angle (α) formed between the maximum inner annular diameter (DImax) and the maximum outer annular diameter (DOmax) is smaller than the pitch angle (β).

6. 3. The sliding constant velocity joint according to claim 1, wherein the inner joint part (12) is provided with markings (44) indicating the associated maximum or minimum annular diameter (DImax, DImin).

7. 3. The sliding constant velocity joint according to claim 1, wherein the inner ball raceway (20) is manufactured with a manufacturing tolerance of less than 1 / 10 mm and is hard-machined, in particular by cutting.

8. The joint outer portion (11) has a radial thickness (T25) in a longitudinal section passing through the raceway bottom, 3. The sliding type constant velocity joint according to claim 1, wherein a ratio of said radial thickness (T25) to said mean outer annular diameter (DOmid) is 0.075 or less.

9. 3. The sliding type constant velocity joint according to claim 1 or 2, wherein the joint outer part (11) has an inner surface (16), the outer ball raceway (18) is formed on the inner surface (16) toward the radially outward side, and the inner surface (16) is machined.

10. 3. The sliding constant velocity joint according to claim 1, wherein the spherical outer guide surface (26) of the joint inner part (12) is ideally circular in a cross section passing through the joint inner part (12), i.e., manufactured with a manufacturing tolerance of plus / minus 0.03 mm with respect to the nominal outer diameter.

11. 3. The sliding constant velocity joint according to claim 1, wherein the spherical outer guide surface (26) is hardened and machined at least in a partial section.

12. 3. The sliding constant velocity joint according to claim 1, wherein at least a partial peripheral surface of the ball cage (13) is ideally round, i.e., manufactured with a manufacturing tolerance of plus / minus 0.03 mm relative to the nominal peripheral diameter.

13. the ball cage (13) has an outer control surface (17) and an outer free surface (34) curved about a first center point (MK1) and an inner control surface (35) spherical about a second center point (MK2), the first center point (MK1) and the second center point (MK2) each being at an axial distance from a center plane (EK) of the ball cage (13); the ball cage (13) has a minimum radial wall thickness (T13) between the spherical inner control surface (35) and the outer free surface (34); 3. The sliding type constant velocity joint according to claim 1, wherein a ratio of the minimum radial thickness (T13) to a pitch circle diameter (PCD) is less than 0.

08.

14. 3. The sliding constant velocity joint according to claim 1, wherein the balls (14) are manufactured with a manufacturing tolerance of less than plus or minus 4 micrometers with respect to the ball nominal diameter.

15. 3. The sliding constant velocity joint according to claim 1, wherein the inner joint part (12) is bendable relative to the outer joint part (11) by a bending angle (δ) of up to 20°.

16. In the assembled state, under the stretched joint, a joint center plane (EM) is defined, and the outer ball tracks (18) each have a central working section (37m) around the joint center plane (EM) and have bottom-side and opening-side secondary areas (37b, 37o) that run from the central working section (37m) to the bottom (21) and joint opening (19), 3. The sliding constant velocity joint according to claim 1, wherein the outer ball raceway (18) is widened by at least 0.1 mm in the bottom side secondary raceway section (37b) and / or the opening side secondary raceway section (37o) relative to the central working section (37m).

17. 3. The sliding constant velocity joint according to claim 1, wherein the outer ball raceway (18) is mechanically finish-machined before hardening, without chips, in particular by forging, or with chips, in particular by milling.

18. 3. The sliding constant velocity joint according to claim 1, wherein the at least a partial section of the inner ball raceway (20) is machined after hardening.

19. 3. The sliding constant velocity joint according to claim 1, wherein the sliding constant velocity joint (10) is designed as a double offset joint.

20. A method for manufacturing a sliding type constant velocity joint, comprising the steps of: manufacturing a joint outer part (11) having a longitudinal axis (A11), a connection side, an opening side, an inner surface (16), and an outer ball raceway (18), the outer ball raceway (18) is soft finished and subsequently hardened, i.e., remains unmechanically worked after hardening; when viewed in a cross section through the joint outer part (11), the ball contact points of the outer ball raceway (18) define an irregularly shaped outer annular line (RL11) having a maximum outer annular line diameter (DOmax) and a minimum outer annular line diameter (DOmin), the maximum outer annular diameter (DOmax) is greater than the minimum outer annular diameter (DOmin) by an outer diameter difference value (DOdiff) of at least 0.15%; a mean outer annular diameter (DOmid) defined as half the sum of the maximum outer annular diameter (DOmax) and the minimum outer annular diameter (DOmin) [DOmid=(DOmax+DOmin) / 2]; manufacturing a joint inner part (12) having a longitudinal axis (A12), an outer surface, and an inner ball raceway (20), The inner ball raceway (20) is manufactured such that, when viewed in a cross section through the joint inner part (12), the ball contact points (36, 36') of the inner ball raceway (20) define an inner annular line (RL12) having a non-circular shape with a maximum inner annular line diameter (DImax) and a minimum inner annular line diameter (DImin), whereby: the maximum inner annular diameter (DImax) is greater than the sum of the mean outer annular diameter (DOmid) and 0.25 times the outer diameter difference value (DOdiff); the minimum inner annular diameter (DImin) is less than the difference between the mean outer annular diameter (DOmid) and 0.25 times the outer diameter difference value (DOdiff); manufacturing a ball cage (13) having a cage axis (A13), a cage inner surface (35), a cage outer surface (17), and cage windows (15) distributed circumferentially around the cage axis (A13); Inserting the joint inner part (12) into the ball cage (13); inserting the joint inner part (12) with the ball cage (13) into the joint outer part (11), so that the angle (α) formed between the maximum inner annular wire diameter (DImax) and the maximum outer annular wire diameter (DOmax) is less than 30°; a step of inserting balls (14) into the cage windows (15), each of the balls (14) being accommodated in a raceway pair consisting of an outer ball raceway and an inner ball raceway (20); A method comprising:

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