Multi-part fork, method for manufacturing the fork and rear axle steering with such a fork

Abstract

Multi-part fork (1) for a rear axle steering system (20), comprising • a base body (2) which has at least one connecting pin (5, 6) on two opposite sides, • a first cheek (3) and a second cheek (4) which are arranged substantially parallel to each other on opposite sides of the base body (2) such that openings (10) in the respective cheek are aligned, wherein the respective connecting pin (5, 6) is passed through a respective recess (7, 8) on the respective cheek (3, 4) in order to fix the respective cheek (3, 4) to the base body (2) by cold forming an end section of the respective connecting pin (5, 6) protruding from the respective recess (7, 8).

Description

[0001] The invention relates to a multi-part fork for a rear axle steering system and a method for manufacturing the multi-part fork. Furthermore, the invention relates to a rear axle steering system for a vehicle with such a multi-part fork.

[0002] For example, DE 10 2017 201 352 A1 discloses a multi-part articulated fork for a rear axle steering system for connection with a joint, comprising two preferably exactly parallel webs with web surfaces, a web connecting the webs, and a mounting bore arranged in the web and having a longitudinal axis, wherein the web surfaces form an angle of inclination with the longitudinal axis in the range of 20° to 70°. This range corresponds to a large helix angle. The articulated fork is designed in two parts, with one web being a separate component. The webs are arranged parallel to each other. A base body manufactured as a forging comprises the web and an integrated web. A second web, additionally designed as a sheet metal part, is manufactured separately and connected to the base body.A method is proposed for connecting the second cheek to the base body, in which the component approximations are achieved using screw bolts, possibly via threaded holes machined into the web, as well as through targeted cold forming to create mounting bosses and subsequent formation of circumferential deformation ridges. At large helical angles, the problem arises that the fork can no longer be connected to the steering linkage via a central mounting hole, as the cheeks can obscure the mounting hole.

[0003] The object of the invention is to provide an alternative fork for a rear axle steering system. In particular, the fork should be simple and inexpensive to manufacture and suitable for large steering angles. This object is achieved by the subject matter of claim 1 and by the subject matter of claim 10. Preferred embodiments can be found in the dependent claims, the description, and the figures.

[0004] A multi-part fork for a rear axle steering system according to the invention comprises a base body having at least one connecting pin on two opposite sides, a first cheek and a second cheek arranged substantially parallel to each other on opposite sides of the base body, wherein the respective connecting pin is guided through a respective recess in the respective cheek to fix the respective cheek to the base body by cold forming an end section of the respective connecting pin protruding from the respective recess. Thus, the two cheeks rest substantially parallel to the base body and are firmly connected to the base body by the connecting pins. For this purpose, the connecting pins are guided through the recesses provided for this purpose in the cheeks and formed in such a way that the cheeks are inseparably connected to the base body.A connecting pin is a feature on the base body, preferably cylindrical, designed to be plastically deformed during fork assembly to fix the respective side to the base body. The geometry of the recess on each side essentially corresponds to the geometry of the connecting pin. For example, the recess may be a cylindrical bore. The length of the connecting pin is greater than the wall thickness of the wall in the area of ​​the recess, so that the connecting pin partially protrudes from the recess. The protruding end of the connecting pin is plastically deformed in such a way that the side is firmly connected to the base body. Thus, the fork consists of the base body and the two sides.

[0005] According to one embodiment, at least two connecting pins are formed on two opposite sides of the base body for connecting the respective cheek to the base body. The provision of at least two connecting pins for each cheek improves the fixation of the respective cheek to the base body, thereby creating a reliable anti-rotation device.

[0006] According to one embodiment, the connection between the respective connecting pin and the respective cheek is made by orbital riveting. During the orbital riveting process, an eccentric tool rotates on the free end section of the respective connecting pin, causing the end section to be plastically deformed. This plastic deformation occurs such that the material of the connecting pin expands radially outwards, forming a circumferential deformation bead that comes into contact with an edge region of the respective recess on the respective outer surface of the cheek. This firmly fixes the respective cheek between the base body and the deformed end region of the connecting pin, thereby establishing a permanent mechanical connection between the base body and the respective cheek via the connecting pin.Preferably, the orbital riveting process is controlled such that the deformation of the respective connecting pin occurs gradually in order to minimize stresses in the material and ensure a uniform distribution of the material deformation. For example, the respective cheek is made of a material with a higher hardness than the material of the base body, in particular the connecting pin, thereby creating improved fixation and wear resistance of the connection.

[0007] According to one embodiment, the base body is manufactured by forging. In particular, a mounting bore for a central screw connecting the base body to a steering linkage of a linear drive for the rear axle steering is formed in the base body between the at least two connecting pins. Specifically, the cylindrical bore extends transversely to the respective connecting pin. Furthermore, the base body has a cylindrical section for attaching a bellows, with the mounting bore passing through the cylindrical section designed as a bellows seat. Alternatively, the base body can be manufactured by hot forming or sintering.

[0008] According to one embodiment, both cheeks are made from a single sheet of metal, with the second cheek having a thinner wall than the first. In particular, the respective metal sheet is made of a steel alloy. The respective cheek is preferably stamped and formed, especially bent, from the metal sheet. This improves the manufacturing of the multi-part fork. The wall thickness of the metal sheet refers to its thickness. Therefore, the metal sheets have different thicknesses.

[0009] According to one embodiment, the second cheek is longer than the first. In other words, the second cheek is longer than the first. In particular, both cheeks are curved in essentially the same way. Despite the angle of the helix, the difference in length of the cheeks allows for the alignment of slot-like openings in each cheek, with the openings designed to accommodate an eccentric screw.

[0010] According to one embodiment, the second cheek has a stiffening collar that is at least partially circumferential on at least one of its two end faces. In particular, the stiffening collar is formed on an outwardly facing end face of the second cheek. The stiffening collar is to be understood as a protrusion, in particular a thickening, on the second cheek and extends over at least two, preferably three, of the four edges of the second cheek, thereby increasing the bending stiffness of the second cheek.

[0011] According to one embodiment, at least one of the two cheeks has at least one support surface for the eccentric screw passing through each opening. In particular, both cheeks have at least one support surface for the eccentric screw passing through each opening. Preferably, the openings are designed as elongated holes. Specifically, to form the elongated holes, an H-shaped section is punched out, with two opposing tongues being deformed substantially by 90° to form two support surfaces.

[0012] Furthermore, the invention also relates to a rear axle steering system for a vehicle, comprising a linear drive with a steering linkage and at least one multi-part fork according to the invention, which is arranged on the steering linkage. Preferably, a multi-part fork according to the invention is arranged at both ends of the steering linkage, wherein the linear drive has an electric actuator which acts on the steering linkage via a threaded drive to effect an axial displacement.

[0013] Furthermore, the invention also relates to a method for manufacturing the multi-part fork for the rear axle steering, wherein first the base body with the mounting bore and the at least two connecting pins, as well as the two cheeks, each with at least one recess, are provided, wherein the first cheek is then mounted on one of the two opposite sides of the base body, wherein the at least one connecting pin is guided through the at least one recess on the first cheek, wherein the end section of the connecting pin protruding from the recess is then cold-formed to fix the first cheek to the base body, wherein the base body is then mounted to the steering linkage of the linear drive of the rear axle steering via the mounting bore, wherein the second cheek is then mounted on the opposite side of the base body.wherein the at least one connecting pin is guided through the at least one recess on the second cheek, wherein finally the end section of the connecting pin protruding from the recess is cold-formed to fix the second cheek to the base body. The method according to the invention creates a multi-part fork that is easy and cost-effective to manufacture and is suitable for large helix angles, in particular in the range of 20° to 70°, between a longitudinal axis of the mounting bore on the base body and the respective cheek surface.

[0014] Further measures improving the invention are described in more detail below, together with a description of a preferred embodiment of the invention, with reference to the figures. Fig. 1 a schematic representation of a multi-part fork according to the invention, Fig. 2 a schematic representation of the multi-part fork according to the invention in a partially assembled state, Fig. 3 a schematic representation of the multi-part fork according to the invention in an unassembled state and Fig. 4 a simplified schematic view of a rear axle steering system according to the invention.

[0015] In Fig. 1, Fig. 2 and Fig. Figure 3 shows the multi-part fork 1 according to the invention from different perspectives and in different states. The fork 1 is designed for a rear axle steering system 20, which is Fig. Figure 4 shows the assembly and comprises a base body 2 produced by forging, as well as a first cheek 3 and a second cheek 4, each made from a sheet of metal. As shown in Figure 4, the assembly comprises a base body 2 produced by forging, a first cheek 3 and a second cheek 4, each made from a sheet of metal. Fig. As is clearly evident from Figure 1, the two cheeks 3, 4 are arranged essentially parallel to each other on opposite sides of the base body 2. As can be seen from Figure 1. Fig. As can be seen from Figure 3, the base body 2 has two connecting pins 5, 6 on each of its two opposite sides, which are guided through respective recesses 7, 8 in the respective cheek 3, 4. As can be seen particularly well from Fig. As shown in Figure 1, the end sections of the respective connecting pins 5, 6 protrude axially from the respective recesses 7, 8 on the respective cheek 3, 4. In order to fix the respective cheek 3, 4 to the base body 2, the respective end section of the respective connecting pin 5, 6 is deformed by cold forming, in particular by orbital riveting.

[0016] As from Fig. 2 and Fig. As can be seen from Figure 3, a fastening bore 12 is formed on the base body 2, the longitudinal axis of which is transverse to the longitudinal axes of the connecting pins 5, 6. The base body 2 further comprises a cylindrical section 13 for fastening a bellows 22, which is Fig. Figure 4 shows the second cheek 4 having a thinner wall than the first cheek 3, and its length is greater than that of the first cheek 3. Furthermore, the second cheek 4 has a partially circumferential stiffening collar 9 on its outer end face, which increases the bending stiffness of the thinner-walled second cheek 4. Both cheeks 3 and 4 have two support surfaces 11 at each opening 10 for the passage of an eccentric screw (not shown). As can be seen particularly well from Fig. As can be seen from Figure 1, the support surfaces 11 extend essentially perpendicularly outwards from the respective end face of the respective cheek 3, 4. The support surfaces 11 are produced by punching the opening 10 and forming two tongues by essentially 90°.

[0017] In Fig. Figure 2 shows the fork 1 before the orbital riveting of the connecting pins 5, which protrude from the first cheek 3. In other words, the first cheek 3 is first mounted on one of the two opposite sides of the base body 2, with the connecting pins 5 being guided through the recesses 7 on the first cheek 3. Then, the end sections of the connecting pins 5 protruding from the recesses 7 are orbital riveted to fix the first cheek 3 to the base body 2. Afterward, the base body 2 is mounted to the steering linkage 21 of the linear drive 23 of the rear axle steering 20 via the mounting bore 12. Then, the second cheek 4 is mounted on the opposite side of the base body 2, with the respective connecting pin 6 being guided through the respective recess 8 on the second cheek 4. Finally, the end sections of the connecting pins 6 protruding from the recesses 8 are deformed by means of orbital rivets in order to fix the second cheek 4 to the base body 2.If necessary, to align the two cheeks 3, 4 parallel to each other, the second cheek 4 can be at least partially plastically deformed after assembly so that the openings 10 in the respective cheek 3, 4, as in . Fig. 1 shown, aligned.

[0018] According to Fig. Figure 4 comprises a rear axle steering system 20 for a vehicle not shown in detail, a linear drive 23 with a steering linkage 21, which has a fork 1 at each of its free ends as shown in the preceding figures. The rear axle steering system 20 is arranged transversely to a longitudinal axis of the vehicle and is configured to adjust a steering angle at the wheels of the rear axle. For this purpose, the linear drive 23 further comprises an electric actuator that displaces the steering linkage 21 in the longitudinal direction. Reference symbol list 1 fork 2 basic shapes 3 first cheek 4 second cheek 5 connecting pins for first cheek 6 connecting pins for second cheek 7. Recess on the first cheek 8. Recess on the second cheek 9 stiffening collars 10 Breakthrough 11 Support surface 12 mounting holes 13 cylindrical section 20 Rear axle steering 21 Steering linkage 22 bellows 23 Linear drive

Claims

Multi-part fork (1) for a rear axle steering system (20), comprising: • a base body (2) having at least one connecting pin (5, 6) on two opposite sides, • a first cheek (3) and a second cheek (4) arranged substantially parallel to each other on opposite sides of the base body (2) such that openings (10) in the respective cheek are aligned, wherein the respective connecting pin (5, 6) is passed through a respective recess (7, 8) on the respective cheek (3, 4) in order to fix the respective cheek (3, 4) to the base body (2) by cold forming an end section of the respective connecting pin (5, 6) protruding from the respective recess (7, 8). Multi-part fork (1) according to claim 1, characterized in that at least two connecting pins (5, 6) are formed on the base body (2) on two opposite sides for connecting the respective cheek (3, 4) to the base body (2). Multi-part fork (1) according to one of the preceding claims, characterized in that the connection between the respective connecting pin (5, 6) and the respective cheek (3, 4) is made by orbital riveting. Multi-part fork (1) according to one of the preceding claims, characterized in that the base body (2) is manufactured by forging. Multi-part fork (1) according to one of the preceding claims, characterized in that both cheeks (3, 4) are made from a respective sheet of metal, wherein the second cheek (4) has a smaller wall thickness than the first cheek (3). Multi-part fork (1) according to one of the preceding claims, characterized in that the second cheek (4) has a greater length than the first cheek (3). Multi-part fork (1) according to one of the preceding claims, characterized in that the second cheek (4) has a stiffening collar (9) at least partially circumferential on at least one of the two end faces. Multi-part fork (1) according to one of the preceding claims, characterized in that at least one of the two cheeks (3, 4) has at least one support surface (11) for an eccentric screw guided through the opening (10) at the respective opening (10). Rear axle steering (20) for a vehicle, comprising a linear drive (23) with a steering linkage (21) and at least one multi-part fork (1) according to one of claims 1 to 8, which is arranged on the steering linkage (21). Method for manufacturing a multi-part fork (1) for a rear axle steering system (20), comprising the following steps: • Providing a base body (2) with a mounting bore (12) having at least one connecting pin (5, 6) on each of two opposite sides, • Providing a first cheek (3) and a second cheek (4), each with at least one recess (7, 8), • Mounting the first cheek (3) on one of the two opposite sides of the base body (2), wherein the at least one connecting pin (5) is guided through the at least one recess (7) on the first cheek (3), • Cold forming an end section of the connecting pin (5) projecting from the recess (7) to fix the first cheek (3) to the base body (2), • Mounting the base body (2) via the mounting bore (12) to a steering linkage (21) of a linear drive (23) of the rear axle steering system (20),• Mounting the second cheek (4) on the opposite side of the base body (2), wherein the at least one connecting pin (6) is guided through the at least one recess (8) on the second cheek (4), • Cold forming an end section of the connecting pin (6) protruding from the recess (8) in order to fix the second cheek (4) to the base body (2).

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