Universal joint for steering shaft

Abstract

This utility model relates to a universal joint (1) for a steering shaft of a motor vehicle, the universal joint including a universal joint cross shaft (3) having two pairs of journals (4) arranged at right angles to each other, and two universal joint forks (2), the universal joint forks having holes (22) respectively constructed in opposing arms (21) having hollow cylindrical inner walls, in which journals (4) are supported in rolling bearings (5) in a manner rotatable about the journal axis (Z), the rolling bearings having a rolling space between an outer sleeve (51) fixed in the hole (22) and the journals (5). The rolling element (52) is arranged such that at least one retaining protrusion (6) protrudes radially inward into the opening cross section of the hole (22) and is made by local plastic deformation of the edge section (23) of the hole (22) in such a way that a molded portion (61) is introduced axially recessed in the direction of the journal axis (Z) on the outer side of the universal joint fork (2) opposite to the journal (4) and having the edge section (23), spaced apart from the hole (22), wherein the material of the universal joint fork (2) undergoes plastic deformation between the molded portion (61) and the hole (22) to construct the retaining protrusion (6).

Description

Technical Field

[0001] This utility model relates to a universal joint for a motor vehicle steering shaft. The universal joint includes a universal joint cross shaft with two pairs of journals arranged at right angles to each other, and two universal joint forks. These two universal joint forks have holes with hollow cylindrical inner walls respectively constructed in opposing arms. In these holes, journals are supported in rolling bearings in a manner that allows them to rotatably about the journal axis. The rolling bearings have rolling elements arranged rotatably between an outer sleeve fixed in the hole and the journal. At least one retaining protrusion radially inwardly protrudes into the opening cross section of the hole. This is manufactured by local plastic deformation of the edge section of the hole, i.e., a molded portion axially recessed along the direction of the journal axis is introduced spaced apart from the hole on the outer side of the universal joint fork opposite to the journal, wherein the material of the universal joint fork undergoes plastic deformation between the molded portion and the hole to construct the retaining protrusion. Background Technology

[0002] In motor vehicles, the steering shaft is used to transmit steering torque introduced into the steering wheel to the steering transmission mechanism via the steering spindle and intermediate shaft. To compensate for angular deviations, at least one, and typically two, universal joints are integrated along the direction of the steering shaft. These universal joints are typically integrated between the steering spindle and intermediate shaft, and between the intermediate shaft and the steering transmission mechanism.

[0003] In its basic structure, each universal joint has two universal joint forks mounted on the ends of the shaft. Each universal joint fork has two arms extending axially along the axis and facing each other transversely to the axis. The universal joint cross shaft has two pairs of universal joint journals, simply referred to as journals, projecting radially in opposite directions. These journals are arranged on journal axes that intersect at right angles. Two of the journals in a pair are each supported in one arm of the universal joint fork in a manner that allows them to rotate about their journal axis in a journal bearing. This journal bearing is constructed as a rolling bearing, typically a needle roller bearing, and the journal axis extends transversely to the axis through the arm.

[0004] A rolling bearing has rolling elements arranged between an outer sleeve (which constitutes the outer ring of the rolling bearing) and a journal, which are capable of rolling on the outer circumferential surface of the journal or on an inner sleeve mounted on the journal. The outer sleeve may be constructed in the shape of a tube segment or a can, and has an axial end side that faces outward when viewed from the universal joint cross shaft, and is fixed in a hole that passes through a corresponding arm along the direction of the journal axis and extends axially outward when viewed from the universal joint cross shaft.

[0005] To secure the rolling bearing in the bore, as known from EP 3 396 189 B1, retaining protrusions are provided that project radially inward from the inner wall of the bore into the cross-section of the bore. These retaining protrusions secure the outer sleeve and prevent the outer sleeve from moving axially outward from the bore.

[0006] The method for manufacturing a retaining protrusion, known from EP 3 396 189 B1, firstly involves introducing a molded portion radially spaced relative to the bore edge on the outer side of the universal joint fork, away from the journal, thereby retaining a thin-walled, axially outwardly extending section between the molded portion and the outwardly open cross-section of the bore. Next, by applying a deformation force axially from the outside, the thin-walled section undergoes bending deformation, bending inward and constructing the retaining protrusion.

[0007] Manufacturing thin-walled sections with a defined wall thickness is relatively costly, and to provide sufficient axial length for bending, a relatively large axial clearance is required between the end face of the sleeve and the outer edge of the bore; that is, the bore must protrude more axially relative to the journal. Therefore, it is necessary to either increase the thickness of the arm or reduce the axial bearing length of the rolling bearing. Another disadvantage is that, to bend the section, an externally applied axial deformation force may undesirably cause axial displacement of the sleeve within the bore. To reliably prevent this, in a design known from EP 3396 189 B1, an axial clearance is provided between the retaining protrusion and the end face of the sleeve, so that the sleeve does not contact the bent section at the end face during bending deformation. However, this requires an additionally lengthened bore, and the axial clearance of the sleeve relative to the retaining protrusion makes it impossible to definitively define and fix the axial position of the sleeve.

[0008] In view of the above problems, the objective of this invention is to provide a functionally optimized retaining protrusion. Utility Model Content

[0009] According to this invention, the task is accomplished using the universal joint of this invention.

[0010] In a method of manufacturing a universal joint for a steering axle of a motor vehicle, the universal joint includes a universal joint cross shaft having two pairs of journals arranged at right angles to each other, and two universal joint forks having holes with hollow cylindrical inner walls respectively constructed in opposing arms. Journals in these holes are supported in rolling bearings in a manner rotatable about a journal axis. The rolling bearings have rolling elements arranged rotatably between an outer sleeve fixed in the hole and the journal, wherein at least one element radially inwardly protrudes into the hole. The retaining protrusion in the cross-section of the opening is manufactured by local plastic deformation of the edge section of the hole in the following manner: a molded portion that is axially recessed in the direction of the journal axis is introduced at a distance from the hole in the outer side of the universal joint fork that is opposite to the journal and has an edge section, wherein the material of the universal joint fork undergoes plastic deformation between the molded portion and the hole to construct the retaining protrusion. According to the present invention, when the molded portion is plastically molded by a forming punch pressed into the edge section in the axial direction, the retaining protrusion is manufactured by radially inward flow deformation.

[0011] The forming punch, along the so-called press-in direction or molding direction (which is axially or substantially axially oriented relative to the journal axis), presses from the outside into the material of the universal joint fork, spaced apart from the edge of the hole, in the edge region, so as to mold the molded portion through its negative molding plasticity. Thus, by definition, the molding direction is axially directed from the outside towards the end side of the journal, or towards the end side of the outer sleeve disposed thereon.

[0012] Importantly, the method according to this invention involves a material flow that is substantially transverse to the molding direction, generated by the plastic deformation that occurs when the forming punch penetrates axially into the outer side of the universal joint fork. The material is thus pushed perpendicular to the journal axis. Here, the material flows radially inward toward the journal axis; that is, the material flows inward from the inner wall of the hole into the hole's cross-section. This method creates a radially inwardly projecting flow protrusion, which can also be called a flow nose. The radial material flow through the flow protrusion creates a retaining protrusion.

[0013] In the method according to this invention, the radial flow deformation occurs transversely to the journal axis. That is, during the manufacture of the retaining protrusion, the material of the universal joint fork flows inward from the inner wall of the hole, transversely to the insertion direction of the forming punch, into the open cross-section of the hole. The main advantage here is that when the retaining protrusion is manufactured to be directly adjacent to the end side of the outer sleeve in the axial direction, or even manufactured to have the same axial height as the end side of the outer sleeve, no or only a very small axial force is applied to the outer end face of the outer sleeve located in the hole through the radial material flow. This effectively avoids undesirable consequences during the manufacture of the retaining protrusion, such as axial displacement or misalignment of the outer sleeve of the rolling bearing, or axial misalignment of the universal joint cross shaft.

[0014] An additional advantage is that, by means of the retaining protrusion that contacts the end side of the outer sleeve, the journal bearings of the journal pair, which are opposite each other in the universal joint fork, can be supported and positioned in a defined manner in a form fit, so that, in fact, no axial displacement of the outer sleeve or misalignment of the cross shaft occurs during assembly or even during operation.

[0015] Another advantage is that, compared to the aforementioned prior art, the required axial protrusion of the hole beyond the journal is smaller, which is given by the axial distance between the end side of the outer sleeve and the outer edge of the hole, whereas in the prior art, a wall section that can be axially bent relative to the end side of the outer sleeve must be provided.

[0016] In the prior art, axial bending is performed towards the end of the bearing sleeve, which is generated by axial bending deformation. In contrast, according to the present invention, the material is specifically pushed radially inward by a radial material flow. Accordingly, in the present invention, it is not necessary to provide additional axial space before deformation. The resulting advantage is that the axial length of the bore relative to the journal can be shorter, thereby selectively providing a larger axial bearing length for the rolling bearing, or enabling a smaller diameter of the universal joint fork (measured radially on the outside of the universal joint fork arm) for a more compact and lighter structure.

[0017] Another advantage over existing technologies is that the radially shaped portion formed by the retaining protrusion can provide a greater axial holding force than the radially shaped portion formed by known bending retaining sections. While thin-walled sections can indeed bend back under high axial loads, in this invention, the reversal of plastic flow deformation is effectively eliminated.

[0018] Preferably, it can be configured such that, during flow deformation, the radially inwardly pushed material flows around the edge section of the outer sleeve.

[0019] An outer sleeve is located in the bore, wherein the outer sleeve, with its preferably cylindrical circumferential surface, radially abuts against the cylindrical inner surface of the bore from the inside. The rolling bearing can, for example, be press-fitted into the bore. The axial end face of the outer sleeve (pointing axially outward relative to the journal axis when viewed from the universal joint cross shaft, that is, pointing outward from the bore relative to the universal joint axis) has a predetermined axial distance from the outer side of the universal joint arm, and therefore from the edge face of the bore. A surrounding edge is constructed between the circumferentially surrounding cylindrical circumferential surface of the outer sleeve and its axial end face. The bore has an axial protrusion relative to the outer sleeve; that is, the edge section of the bore is axially spaced outward relative to the edge along the journal axis.

[0020] According to this invention, during flow deformation, the material of the universal joint fork, which is plastically pushed and flows radially inward, is radially supported on the circumferential surface of the outer sleeve through the edge segments running circumferentially, and further flows radially inward beyond the end face of the outer sleeve (i.e., in the region of the aforementioned protrusion). Here, the material flows around the surrounding end edges of the outer sleeve and axially surrounds the end face of the outer sleeve.

[0021] In the prior art method described at the beginning, the material segment bends freely axially inward toward the end face, i.e., the material segment deforms relative to the end face but does not contact it. In contrast, according to the present invention, a radial material flow is generated. This material flow radially inward contacts the circumferential surface of the outer sleeve and is blocked there, causing the flowing material to be further radially displaced from the axial exterior of the journal, thereby constructing a retaining protrusion. During this flow, the material flows radially inward on the end face and contacts it. Thus, an effective axial fit is constructed between the outer sleeve and the retaining protrusion, which can be achieved through direct axial contact between the retaining protrusion and the end face, preferably axially clear. Advantageously, no or only negligible axial force is applied from the outside to the end face by the flowing material, so that the outer sleeve is not, or at least not significantly, loaded inwardly onto the journal cross shaft, and correspondingly, the axial fit of the outer sleeve in the bore is not affected.

[0022] In an advantageous manner, the molded portion may be molded at least to the axial position on the end side of the outer sleeve.

[0023] Here, the depth of the molding portion (measured from the outer side of the universal joint arm where the molding portion is introduced) is equal to or greater than the axial protrusion of the hole (measured between the end side of the outer sleeve and the outer side of the universal joint arm). This allows for a reliable form-fitting flow around the end edge of the outer sleeve through the radially inward plastic influx of material during molding. In the aforementioned prior art, the depth is always less than the protrusion.

[0024] An extension of this method can be configured such that, following radial flow deformation, flow deformation occurs in the circumferential direction. For this purpose, axial pressure is applied to the radially inwardly formed flow protrusion, thereby generating further plastic deformation. This pressure can be axially supported on the outer sleeve to produce plastic flow deformation. Here, the material radially inwardly protruding into the bore cross-section is axially upset and flows circumferentially relative to the journal axis. This axial support can be performed on the end side of the outer sleeve, as this end side is firmly and reliably clamped in the bore by the previous radial flow deformation. As a result, the retaining protrusion is widened in the circumferential direction. Therefore, measured separately in the circumferential direction, the retaining protrusion manufactured in this way is wider than the molded portion.

[0025] Preferably, multiple molded parts are manufactured in a manner that distributes them around the hole.

[0026] In a universal joint for a motor vehicle steering axle, the universal joint includes a universal joint cross shaft having two pairs of journals arranged at right angles to each other, and two universal joint forks. Each universal joint fork has a hole with a hollow cylindrical inner wall, constructed in opposing arms. Journals in these holes are supported in rolling bearings in a manner rotatable about the journal axis. The rolling bearings have rolling elements arranged rotatably between an outer sleeve fixed in the hole and the journal. At least one retaining protrusion radially inwardly protrudes into the opening cross-section of the hole, manufactured by localized plastic deformation of the edge section of the hole, such that a molded portion axially recessed along the journal axis is introduced, spaced apart from the hole, on the outer side of the universal joint fork opposite to the journal, wherein the material of the universal joint fork undergoes plastic deformation between the molded portion and the hole to construct the retaining protrusion. According to the present invention, the retaining protrusion is constructed as a radially convex, arched, flowing protrusion.

[0027] The universal joint according to this invention is manufactured by means of the method according to this invention and can have all the features and combinations thereof described above in conjunction with the method according to this invention. Conversely, all the specific features of the universal joint described below can be implemented by means of the method according to this invention.

[0028] A flow protrusion (which may also be called a flow nose) is a bulge or raised plastically formed portion that protrudes radially inward from the inner wall of a hole, created by pushing material in the radial direction through flow deformation. It does not produce bending deformation as in the prior art. This allows the outer sleeve to be held in an improved, more precisely positioned manner.

[0029] Advantageously, the flowing protrusions fit snugly around the outer sleeve.

[0030] During flow deformation, material pushed radially inward flows around the edge section of the outer sleeve. As a result, the outer sleeve is at least partially embedded in the flow deformation section, creating a form fit that acts axially. This ensures improved axial support and positioning of the rolling bearing.

[0031] It is possible that the flow protrusion contacts the outer sleeve.

[0032] Here, the end face of the outer sleeve is axially abutted against the retaining protrusion in a direct contact manner, thereby achieving axial, clearance-free positioning and fixation of the rolling bearing in the arm.

[0033] It can be set to measure separately in the circumferential direction, keeping the protrusion wider than the molded portion. This can improve the support of the form fit of the rolling bearing. Attached Figure Description

[0034] The advantageous embodiments of this utility model will now be explained in detail with the aid of the accompanying drawings.

[0035] Specifically:

[0036] Figure 1 A three-dimensional view of the universal joint according to the present invention is shown.

[0037] Figure 2 It shows Figure 1 Enlarged detail image,

[0038] Figure 3 An axial longitudinal section along the journal axis is shown.

[0039] Figure 4 With similar Figure 2 The view shows the second embodiment.

[0040] Figure 5 Similar to Figure 3 The dissection was shown according to Figure 4 The longitudinal section of the implementation method. Detailed Implementation

[0041] In different accompanying drawings, the same parts are always given the same reference numerals, and therefore are usually named or mentioned only once each.

[0042] Figure 1 A three-dimensional view shows a universal joint 1 according to the present invention. The universal joint includes two identically constructed universal joint forks 2, each having two arms 21 facing each other about a centerline W.

[0043] The universal joint cross shaft 3 has two pairs of journals 4 arranged at right angles to each other. When viewed from the axis W, these journals extend outward along their intersecting journal axes Z.

[0044] Figure 2 An enlarged view of arm 21 is shown, and Figure 3 A longitudinal section along the journal axis Z is shown.

[0045] As in Figure 3 As can be seen, the universal joint arm 21 has a cylindrical hole 22 that passes through the journal axis Z axially. A rolling bearing 5 is inserted into this cylindrical hole, which constitutes a journal bearing. The rolling bearing includes an outer sleeve 51 and rolling elements 52, such as needle rollers, in the press-fit hole 22, which are capable of rolling on the outer periphery of the journal 4.

[0046] In this embodiment, the outer sleeve 51 is constructed in the shape of a cylindrical can and has a closed end side 53 in front of the outer end of the journal 4.

[0047] An edge region 23 surrounding the outlet of the hole 22 is constructed on the outer side of arm 21. (As in...) Figure 2 As shown in the illustration. In the illustrated embodiment, in this edge region, each journal 4 is constructed with a total of four retaining protrusions according to the present invention by means of the method according to the present invention. These retaining protrusions project radially inward from the inside into the open cross-section of the hole 22, and are axially supported from the outside on the outer end side 53 of the outer sleeve 51.

[0048] According to this invention, each retaining protrusion 6 is manufactured as a flow protrusion by radial flow deformation of the material of the arm 21 in the edge region 23 of the hole 22. Accordingly, the retaining protrusion is configured as a radially convex arched flow protrusion.

[0049] According to the method of this utility model for manufacturing the retaining protrusion 6, Figure 3 The diagram is schematically shown. Here, the forming punch 7 is axially pressed into the edge region 23 from the outside along the journal axis, entering the outer side of the arm 21 with a gap from the hole 22, as shown in... Figure 3 As indicated by the downward-pointing arrow. The molding portion 61 is thus plastically molded. Here, the material is plastically pushed, and a material flow is generated along the radially inward flow direction F, as shown in... Figure 3 As indicated by the arrows, the material pushed by the radial material flow collides radially from the outside with the outer peripheral surface of the outer sleeve 51, and continues to flow inward along the end side 53 in the direction of the journal axis Z. In other words, the material flows around the edge section of the outer periphery of the outer sleeve 51 and its end side 53, thereby creating an effective form fit in the axial direction.

[0050] Preferably, the molding portion 61 has an axial depth T measured from the outer side of the arm 21 to the bottom of the molding portion, which is equal to or greater than the axial distance A of the end side 53 measured to the outer side of the arm 21. This is in Figure 3 and Figure 5 As shown in the image.

[0051] Figure 4 and Figure 5 It shows in Figure 2 and Figure 3An extended embodiment of the above is shown. In this extended embodiment, the retaining protrusion 6 is plastically deformed by an axial pressure through another flow of material directed in the circumferential direction. Therefore, the retaining protrusion 6 has a width B measured in the circumferential direction, which is greater than the width E of the molding portion 61, also measured in the circumferential direction. The axial pressure applied to achieve this plastic deformation can be easily supported by the outer sleeve 51, which is reliably and firmly clamped in the hole 22 by the material flowing radially inward during the previous plastic deformation.

[0052] Explanation of reference numerals in the attached figures

[0053] 1 universal joint

[0054] 2 universal joint forks

[0055] 21 arms

[0056] 22 holes

[0057] 23 Edge Section

[0058] 3-way universal joint cross shaft

[0059] 4 journals

[0060] 5 rolling bearings

[0061] 51 Outerwear

[0062] 52 rolling elements

[0063] 53 end side

[0064] 6. Maintain the protrusion

[0065] 61 Molding Department

[0066] 7-forming punch

[0067] W axis

[0068] Z-axis journal axis

[0069] F Flow direction

[0070] T Depth

[0071] A Spacing

[0072] B6 width

[0073] Width of E 61

Claims

1. A universal joint for a steering shaft, the universal joint comprising a universal joint cross shaft (3) having two pairs of journals (4) arranged at right angles to each other, and two universal joint forks (2) having holes (22) respectively constructed in opposing arms (21) having hollow cylindrical inner walls, in which journals (4) are supported in rolling bearings (5) in a manner rotatable about a journal axis (Z), the rolling bearings having rolling elements (52) arranged rotatably between an outer sleeve (51) fixed in the holes (22) and the journals (4), wherein, At least one retaining protrusion (6) protrudes radially inward into the opening cross-section of the hole (22), formed by local plastic deformation of the edge section (23) of the hole (22), namely, a molded portion (61) spaced apart from the hole (22) and axially recessed in the direction of the journal axis (Z) is introduced on the outer side of the universal joint fork (2) opposite to the journal (4) having the edge section (23), wherein the material of the universal joint fork (2) undergoes plastic deformation between the molded portion (61) and the hole (22) to construct the retaining protrusion (6). Its features are, The protrusion (6) is constructed as a radially convex, arched flow protrusion.

2. The universal joint according to claim 1, characterized in that, The shape of the flowing protrusion (6) fits around the outer sleeve (51).

3. The universal joint according to claim 2, characterized in that, The flow protrusion (6) contacts the outer sleeve (51).

4. The universal joint according to any one of claims 1 to 3, characterized in that, The protrusion (6) is wider than the molded part (61).

5. The universal joint according to any one of claims 1-3, characterized in that, The molded portion (61) is molded at least at the axial position of the end side (53) of the outer sleeve (51).

6. The universal joint according to any one of claims 1-3, characterized in that, Multiple molded parts (61) are distributed around the hole (22).

Images