Method for producing a trailing arm for a wheel suspension unit of a motor vehicle

Abstract

Method for producing a trailing arm (102) for a wheel suspension unit of a motor vehicle, with a first end (105) for the vehicle-side connection and a second end (109) for connection to a wheel carrier (103), wherein the trailing arm (102) is bent and / or angled and is made at least partially from a fiber-reinforced plastic, characterized in that the trailing arm (102) consists at least partially of a molded tube (10) made of braided and / or wound continuous fibers (11) which are cross-linked with a matrix of plastic, and the shape of the molded tube (10) predetermines the basic shape of the trailing arm (102), wherein the shape of the molded tube is produced by wrapping and / or braiding a core, and wherein the core is inflated or compressed after wrapping and / or braiding.

Description

The invention relates to a method for producing a trailing arm for a wheel suspension unit of a motor vehicle according to the preamble of claim 1.DE 20 2015 103 040 U1 closest to the invention discloses a wheel suspension unit for a motor vehicle, at least having a longitudinal control arm, having a first end for the vehicle-side connection and a second end for the connection to a wheel carrier, wherein the longitudinal control arm is manufactured at least partially from a fiber-reinforced plastic.DE 10 2013 111 701 A1 discloses a method for producing a connecting element for a chassis of a motor vehicle, having the steps: providing a ball joint with a ball joint cage, providing a mold core, forming a base body of the connecting element by braiding or winding the ball joint cage and the mold core with fibers or by folding over the ball joint cage and the mold core with fiber braid blanks, displacing the fibers or fiber braid blanks with a potting resin, and releasing the mold core from the base body.Trailing arms form part of the wheel suspension in motor vehicles. Such a longitudinal link can be pivotably connected on the one hand to the vehicle frame, an auxiliary frame or the vehicle body and on the other hand firmly to a wheel carrier on which the actual axis of rotation of the wheel is in turn arranged. In addition, at least one suspension arm can engage on the wheel carrier, for example, which is pivotably connected to the latter. In addition to these pivotable designs, there are designs in which the trailing arm is firmly connected to the vehicle frame and, due to a given elasticity, enables a movement of the wheel carrier connected thereto. Under certain circumstances, the wheel carrier is also not directly connected to the trailing arm, but is fastened to a cross member which connects mutually opposite trailing arms to one another.From the prior art, trailing arms are known which are formed from steel sheets. For example, US 2007 / 0 007 741 A1 discloses a trailing arm arrangement in which a sword-shaped trailing arm is formed by a sheet metal forming process. A reinforcement member is also formed in a sheet metal forming process.However, there are various requirements for the trailing arm which are difficult to meet with a steel-sheet-shaped member. On the one hand, the trailing arm should be as stiff as possible in the longitudinal direction in order to absorb the torques during braking and acceleration processes. However, the wheel carrier connected to the trailing arm is normally suspended via a plurality of lateral connections (transverse arms etc.), resulting in a kinematic overdetermination. Therefore, in the event of vertical transverse and torsional movement of the wheel, the trailing arm should not be stiff, as some flexibility is necessary to resolve the overdetermination. However, in trailing arms made of steel sheets, this flexibility leads to unattenuated oscillations at low frequencies, which is undesirable in terms of NVH (noise, vibration, roughness) aspects. In addition, the weight of a component made of steel sheet is undesirably high in view of the current trend of saving weight and reducing fuel consumption associated therewith.It has therefore already been proposed to use trailing arms made of a fiber-reinforced plastic. For example, DE 20 2015 103 040 U1 discloses a wheel suspension unit for a motor vehicle having at least one longitudinal control arm which is manufactured at least partially from a fiber-reinforced plastic. In this case, a plurality of different plastics and / or different fibers can be used. A trailing arm made of a fiber-reinforced plastic is also known from DE 10 2012 221 682 A1. This trailing arm is rigidly connected on one side to a steering knuckle and on the other side to the vehicle. WO 2015 / 197 279 A1 and WO 2016 / 0 051 25 A1 likewise disclose chassis control arms made of fiber composite materials.Although the known fiber-reinforced vehicle control arms fulfil their function, the field of manufacturing fiber-reinforced longitudinal control arms, in particular, still offers room for improvements.The invention is based on the object of providing a trailing arm for a wheel suspension of a motor vehicle, which in particular can be easily manufactured in various configurations.According to the invention, the object is achieved by methods for producing a trailing arm for a wheel suspension unit of a motor vehicle having the features of claim 1.A method for producing a trailing arm for a wheel suspension unit of a motor vehicle is disclosed, having a first end for the vehicle-side connection and a second end for the connection to a wheel carrier, wherein the trailing arm is designed to be bent and / or angled and is manufactured at least partially from a fiber-reinforced plastic. According to the invention, the trailing arm consists at least partially of a shaped tube made of braided and / or wound continuous fibers which are crosslinked with a matrix made of plastic, wherein the shape of the shaped tube defines the basic shape of the trailing arm, wherein the shape of the shaped tube is produced by winding and / or braiding a core, and wherein the core is inflated or compressed after winding and / or braiding.Further, particularly advantageous embodiments of the invention are disclosed in the dependent dependent dependent claims.It should be noted that the features and measures individually listed in the following description can be combined with one another in any technically meaningful manner and reveal further configurations of the invention. The description additionally characterizes and specifies the invention, in particular in conjunction with the figures.As already stated above, the trailing arm for the wheel suspension of a motor vehicle has a first end for the vehicle-side connection, and a second end for connection to a wheel carrier. The trailing arm is at least partially made of a fiber-reinforced plastic. According to the invention, the trailing arm consists at least partially of a molded tube made of braided and / or wound continuous fibers, wherein the continuous fibers of the molded tube are crosslinked with a matrix made of plastic. For example, glass, aramid and / or carbon fibers can be used as fibers, wherein various fiber materials can also be mixed. A polyester resin can be used as the matrix material. The trailing arm can also be referred to as a tongue arm.The use of such a molded hose makes it possible to easily produce fiber-reinforced composite trailing arms having various shapes. The trailing arm has the known advantage of saving weight compared to comparable vehicle control arms. The molded tube can also define different shapes of a longitudinal link, which are then molded with a plastic matrix to form the longitudinal member. Optionally, further loose fibers can also be introduced into this plastic matrix. The shaped tube cross-linked with matrix material can enclose an inner cavity, so that the longitudinal member is a hollow component. The space within the shaped tube can, however, also be filled with material. This material may or may not be cross-linked with the fibers of the molded tube. For example, the space within the molded tube can be filled with a plastic, a fiber-reinforced plastic or another material.In this way, a light trailing arm with different shapes and connection elements can be produced, wherein different designs of the trailing arm can be produced by differently preformed shaped hoses. The shape of the shaped tube specifies the basic shape of the trailing arm according to the invention. The longitudinal link is bent and / or angled. In a preferred embodiment, it is an L-shaped trailing arm. In the case of an L-shaped trailing arm, an L-shaped wound shaped hose is thus used, for example.The shape of the cross section of the shaped tube can also be selected to be very variable. For example, the hose can have a round, oval, rectangular and / or polygonal shape in cross section. For rectangular or polygonal shapes, the "corners" are typically slightly rounded due to the braided or wound continuous fiber tubing. The shape of the cross section of the shaped tube can also vary over the length of the trailing arm, so that the shaped tube can have different shapes in different regions. Depending on the intended application and the requirements, the design of the trailing arm can thus be chosen to be flexible, for example between tubular and flat.As already mentioned above, the shape of the shaped tube is produced by winding / braiding a winding mandrel (core) which has the corresponding shape. The winding or braiding process can be carried out with computer and / or robot assistance, whereby continuous fibers are wound around the winding mandrel by placing them one above the other in such a way that a braided tube is produced. The continuous fibers used are either already impregnated with matrix material before the winding process, which subsequently cures together with the fibers, or the wound shaped tube is subsequently impregnated with matrix material, which then cures. Mixed forms of these mentioned procedures are also possible.Various types of winding mandrels can be used. For example, it can be a temporary core which is formed from sand and can be dissolved after the production of the shaped tube. However, it can also be a solid core. Furthermore, they can be rigid or flexible cores. In an alternative embodiment, it is a core that can be inflated to the specific dimensions and geometries. Such a core can be used advantageously for different geometries of a core. In particular, it can be used for geometries with waisted contour.Connection points for connecting the trailing arm to other components of the motor vehicle can also be formed on the trailing arm and in particular in the shaped hose. For example, a bushing for the vehicle-side connection of the trailing arm can be formed at the first end of the trailing arm. This bushing can already be provided as an opening in the shaped hose. It can also be integrated into the molded tube as a separate plastic component. This integrated bushing replaces steel or aluminum bushings often used in the art.At least one component made of another material, in particular metal, ceramic, rubber or a further plastic, can be incorporated in regions of the trailing arm. This integrated component can be used for stabilizing the trailing arm. In particular, the component can be a winding or braiding mandrel which was used to produce the shaped tube. For example, the same plastic can be used for the winding core as for the matrix material, so that the core can optionally remain in the hose. In this case, the core made of matrix material can additionally contain loose fibers and be pressed, for example, to form a core having the required shape.The invention also includes a motor vehicle having at least one trailing arm which is connected to the vehicle by a first end and is connected to a wheel carrier by a second end. The trailing arm is formed according to an embodiment of the invention. FIG. 1 shows a wheel suspension unit according to the prior art. Further advantageous embodiments of the invention are disclosed in the dependent claims and the following description of the figures. The following are shown: FIG. 2 shows a schematic illustration of the production of a shaped tube for a trailing arm, and FIG. 3 shows various producible shapes I-IV of a shaped hose for a trailing arm.In the different figures, identical parts are always provided with the same reference numerals, which is why they are generally also described only once.FIG. 1 shows a possible embodiment of an L-shaped longitudinal control arm 102, for example in the form of a so-called tongue control arm. The trailing arm 102 is part of a wheel suspension unit 101, the basic structure of which is known from the prior art. The wheel suspension unit 101 is essentially composed of three separately manufactured components: the trailing arm 102, a wheel carrier 103 and a brake carrier plate 104. The trailing arm 102 is formed as a substantially L-shaped component and has a rubber bearing bush receiving sleeve 110 at a first end 105, by means of which it can be fastened to the chassis of a vehicle (not shown). The longitudinal member 102 can thus be attached to the vehicle via this first end 105.At a second end 106, the trailing arm 102 is connected to the wheel carrier 103. The wheel carrier 103 has axle receptacles 107, 108 and 109 for various laterally engaging links or arms. The brake carrier plate 104 is laterally attached to the wheel carrier 103.FIG. 2 shows the production of a shaped tube 10 for use in a fiber-reinforced trailing arm. The shape of the molded tube 10 is defined by a winding core 20, which is shown by a dashed line. The winding core 20 is in particular an L-shaped component, so that an L-shaped shaped shaped tube is produced. In the winding process, a plurality of continuous fibers 11 are wound onto the winding mandrel 20 at different angles. The winding direction 30 is marked with an arrow in FIG. 2.FIG. 3 shows various shapes of the cross section A-A of the shaped tube 10, which can be produced during the winding process by a corresponding selection of the winding core. The shape I is an oval shape, while the shape II is rectangular and has rounded corners. The shape III is polygonal with rounded corners. The shape IV is a rectangular or polygonal shape which, however, is constricted in the region of the longer sides, i.e. the distance between the opposite longer sides is smaller than the length of the shorter sides.The geometry of the shape IV (or similar shapes) of a shaped tube can be produced in various ways. For example, in one embodiment, a core is used that can be inflated to the specific dimensions and geometries. Thus, a shaped tube can first be wound and the core can then be inflated into the desired shape of the tube. For example, for the mold IV, a molded tube having a rectangular or polygonal cross section can first be wound and the core used can subsequently be inflated, so that the molded tube expands, for example, on the short sides of the wound molded tube.In a further embodiment, a wound shaped tube is pressed in from the outside with a profile in order to bring it into a specific shape. For example, a profile can be applied from the outside, which acts on the shaped tube in such a way that it is constricted centrally, as in the case of the shape IV. For this purpose, additionally or alternatively, a vacuum can also be used, with which specific regions of the shaped tube are drawn inward. Also in this embodiment, an inflatable core may be used.When forming a winding core, it may be advantageous if the latter is deformed from a matrix material, since the latter is deformable in the wet state. This matrix core can thus be pressed together or inflated. The fiber winding direction can also be used to influence the shape of the molded tube. In particular, a specific internal tension between the longitudinal and transverse directions can be selected.List of reference numbers:10 Shaped tube 11 Fiber, continuous fiber 20 Winding mandrel, winding core 30 Winding direction 101 Wheel suspension unit 102 Longitudinal control arm 103 Wheel carrier 104 Brake caliper plate 105 First end 109 Second end 110 Bushing 107, 108, 109 Axle receptacle

Claims

Method for producing a trailing arm (102) for a wheel suspension unit of a motor vehicle, having a first end (105) for vehicle-side connection and a second end (109) for connection to a wheel carrier (103), wherein the trailing arm (102) is designed to be bent and / or angled and is manufactured at least partially from a fibre-reinforced plastic, characterized in that the trailing arm (102) is composed at least partially of a shaped tube (10) made of braided and / or wound continuous fibres (11), which are crosslinked with a matrix made of plastic, and the shape of the shaped tube (10) specifies the basic shape of the trailing arm (102), wherein the shape of the shaped tube is produced by winding and / or braiding a core, and wherein the core is inflated or compressed after the winding and / or braiding.Method according to claim 1, characterised in that areas of the core are drawn inwards by vacuum.Method according to claim 1 or 2, characterized in that the core is formed from a matrix material which is deformable in the wet state.Method according to claim 3, characterised in that the core is formed from the same matrix material as the shaped tube (10).Method according to one of the preceding claims, characterized in that a cross-section round, oval, rectangular or polygonal shape of the shaped tube (10) is produced.Method according to one of the preceding claims, characterized in that a shape of the cross section of the shaped tube (10) is produced which varies over the length of the longitudinal link (102).Method according to one of the preceding claims, characterized in that a bushing (100) for the vehicle-side connection of the trailing arm (102) is formed as an opening in the shaped hose (10) at the first end (105) of the trailing arm (102).Method according to one of the preceding claims, characterized in that at least one component made of another material is incorporated in regions into the plastic of the trailing arm (102).Method according to claim 8, characterised in that the other material is metal, ceramic, rubber or a further plastic.

Images