Plastic chassis component with elastomer bearing

Abstract

Method for manufacturing a chassis component (10) for supporting a load, comprising at least one damping element (20), with an inner part (21), an external part (25), and an elastomeric part (23) which is provided at least partially between the inner part (21) and the outer part (25), and a housing (30) which surrounds the damping element (20) in a radial direction, wherein the housing (30) is at least partially made of plastic material and is directly and positively connected to the outer part (25) of the damping element (20), with the following steps: Positioning the damping element (20) in a cavity of a plastic application device, wherein the cavity essentially corresponds to the shape of the housing (30), Supporting at least the outer part (25) of the damping element (20), Injecting a plastic material to fill the remaining cavity of the device, and Curing of the plastic material, wherein the positioning of the damping element (20) or the supporting of at least the outer part (25) comprises that the damping element (20) is positioned or supported in the cavity in a rotationally secure manner by means of a positioning means (22).

Description

[0001] The invention relates to a method for producing a chassis component for supporting a load with at least one damping element with an inner part, an outer part and an elastomer part, which is provided at least partially between the inner part and the outer part, and a housing which surrounds the damping element in the radial direction.

[0002] Such chassis components are known per se and are used extensively in motor vehicles, for example to provide spring support for engines, transmissions, drive shafts, axles and other similar components relative to the body of the motor vehicle.

[0003] For this purpose, the housings of engine mounts and their further structural components, as well as transmission cross bridges and structural components in the axle area, have usually been made of aluminum or steel. This has the advantage that the chassis component can be exposed to high mechanical loads due to the stability of these materials. However, housings made of these materials are relatively heavy. It has therefore already been proposed to manufacture parts of the housing or even the entire housing from plastic. For example, DE 10 2007 032 957 A1 discloses a motor vehicle bearing in which part of the housing is made of plastic. To save weight, the plastic part has a hollow space that is stabilized by reinforcing ribs. This ensures that the mechanical requirements of this vehicle component can be met despite the weight savings achieved by using plastic instead of aluminum.

[0004] For chassis components of the type described above, elastomer bearings such as rubber bushings can be used as damping elements in both non-calibrated and calibrated versions for installation in these vehicle components. Calibrated in this context means that the elastomer bearings are made from an inner and an outer part, between which a rubber is vulcanized. As a result, the rubber shrinks during vulcanization, tension builds up between the inner and outer parts. Therefore, after vulcanization, the outer part is pressed together, thereby reducing the tension between the inner and outer parts or bringing the elastomer between the inner and outer parts to the desired tension. This allows the course of the force path characteristic curve of the elastomer bearing to be influenced or adjusted.

[0005] The assembly of the damping element and housing, whether made of aluminum, steel, or plastic, to form the chassis component described above has traditionally been performed as a separate step in a dedicated assembly device, in which the damping element is pressed into a corresponding opening in the housing. Care must be taken to ensure the exact positioning and insertion depth of the damping element into the housing. Furthermore, any surface protection on the outside of the damping element must not be damaged during the assembly process.

[0006] DE 36 24 280 A1 describes a joint for transmission rods in motor vehicles, in particular a rubber joint or ball joint, with an inner joint part movably mounted in a cylindrical outer shell and with a joint eye made of plastic surrounding the outer shell, in which the outer shell is held in the axial direction by stops.

[0007] DE 10 2009 049 400 A1 describes a connecting rod for a torque support with at least two half-shells, each of which has a bulge at at least one end, which, when the half-shells are assembled, form receiving eyes for a bushing, wherein the half-shells are made of fiber-reinforced plastic and have at least one molded-in bead.

[0008] US 2008 / 0 222 841 A1 describes a silent block device comprising a substantially cylindrical silent block, a silent block seat, and a substantially cylindrical housing. The housing and the seat have a first connecting device between the housing and the seat for clamping the seat to the housing. The housing consists of a body formed from several parts and made of a material selected from, among others, thermoplastic, thermosetting, or a plastic matrix composite.

[0009] JP 4658665 B2 describes a torque rod having recessed-shaped fittings in axially intermediate portions of the outer peripheral surfaces of intermediate cylinders and fittings on the inner peripheral surfaces of the outer cylinder portions of a resin-made rod body to be attached to the fittings of the intermediate cylinders to prevent the relative movement of the intermediate cylinders to the outer cylinder portions.

[0010] The invention is based on the object of providing a method for manufacturing a chassis component of the type described above, in which the positioning of the damping element and housing can be carried out simply and precisely. The invention is further based on the object of providing a chassis component of the type described above by this manufacturing method, in which the surface protection of the outer side of the damping element can be protected from damage caused by the joining of the damping element and housing.

[0011] This object is achieved by a method according to claim 1.

[0012] The housing is made at least partially of plastic material and is directly connected to the outer part of the damping element in a form-fitting manner. “Directly form-fitting” means that the plastic material of the housing is applied directly to the outside of the outer part of the damping element. For example, the plastic material can be connected to it directly, i.e. without an adhesive intermediate layer or other intermediate layers. The “application” of the plastic material can be carried out, for example, using an injection molding process in which the outer part of the damping element is overmolded with the plastic material of the housing. This makes it possible to dispense with the assembly step of bringing the damping element and housing together, which was previously necessary. In this way, the previously mentioned disadvantages associated with this assembly step can also be avoided.

[0013] Applying the plastic housing to the outer part of the damping element is therefore advantageous, as the damping element can be precisely positioned in the injection mold and secured there before the plastic is injected. If necessary, suitable positioning aids can be used to securely maintain the damping element's position during the injection process, thus ensuring the desired position relative to the cured housing.

[0014] Another advantage is that, in order to connect the damping element and the housing, no axial press-in forces are exerted on the outside of the outer part of the damping element through the inside of the corresponding recess in the housing, which could previously lead to damage to the outside of the outer part of the damping element.

[0015] Another advantage is that by omitting the previously described assembly step, a manufacturing step can be eliminated. Thus, the production of the plastic housing using an injection molding process can be combined with the joining of the damping element and housing using an injection molding process, thus eliminating both the previously described assembly step and the corresponding assembly device.

[0016] Another advantage is that the positive connection between the damping element and the housing also creates a secure connection in the axial direction. This means that the damping element can only be pressed out of the housing against the forces of the positive connection between the applied plastic of the housing and the outside of the damping element. This creates a secure connection that acts in both axial directions of the damping element, without any forces acting in the radial direction between the damping element and the housing.

[0017] Furthermore, the housing is made of plastic instead of, for example, aluminum or steel, as this reduces the weight of the chassis component.

[0018] According to one aspect of the invention, the housing and damping element enclose each other on one side, preferably on both sides, at least in regions in the axial direction of the damping element. This means that either the damping element is encompassed or enclosed by the housing or, conversely, the housing is encompassed or enclosed by the damping element in such a way that the damping element cannot be pressed out of the housing or at least can only be pressed out by an increased pressing-out force. In other words, the damping element is held in a form-fitting manner at least in one axial direction by at least one radial partial region of the housing in its axial direction, or the housing is held by at least one radial partial region of the damping element. If the damping element is held in the axial direction on both sides by the housing orthe housing from the damping element, the damping element can be held securely in the housing even against higher extrusion forces in both axial directions than was previously the case with a damping element pressed into the housing.

[0019] This advantageous design compared to the known assembly of damping element and housing is only made possible by applying the plastic housing to the outer part of the damping element. Thus, with conventional assembly, at most one side of the housing or the damping element can be designed in such a way that pressing the damping element out of the housing in this axial direction is blocked by corresponding projections or the like. The other side of the housing or the damping element in the axial direction can have no such projections at all or at most very small ones, since the pressing of the damping element into the housing must occur from at least one side of the housing and must not be blocked.

[0020] This limitation is eliminated by applying the plastic housing to the damping element, allowing the damping element to withstand greater extrusion forces than is the case with conventional assembly. This can be achieved by applying the plastic housing to the damping element using an injection molding process, for example, by creating undercuts in the injection mold.

[0021] According to a further aspect of the invention, at least the damping element, preferably the inner part, has a positioning means by means of which it can be held securely against rotation with respect to the axial direction. This allows the damping element to be securely held and positioned during production, for example by means of an injection molding process, by the tool of the injection molding machine engaging in the positioning means. This can be achieved, for example, by a recess on one side and a corresponding elevation on the other side. Alternatively, the damping element or, for example, just the inner part or outer part can be designed to be non-rotationally symmetrical, such as square or oval.

[0022] According to one aspect of the invention, the inner part and / or outer part of the damping element is made, at least in part, of metal, preferably aluminum or steel. This advantageously increases the stability of the damping element.

[0023] According to a further aspect of the invention, the outer part has a stiffening element made of metal at least in some regions. This feature relates to vehicle components which have a combination of two plastics or of a plastic and an elastomer, e.g. a plastic such as PA (polyamide) for the housing and rubber such as NR (natural rubber) as the elastomer part of the damping element. In injection molding processes for such components it is necessary for the tools which position the elastomer component during encapsulation to be relatively stable, i.e. with thick walls, in order to withstand the pressure during encapsulation and to ensure the positioning of the elastomer component even during encapsulation. It is therefore advantageous to insert the outer part into the injection mold, e.g. with a bushing with an outer metal made of steel, which stabilizes the elastomer component.This allows the tools that position the outer part during overmolding to be made thinner and lighter.

[0024] According to one aspect of the invention, the damping element is calibrated. Using a calibrated damping element is advantageous for the bearing, as it can have a predeterminable force path characteristic. Furthermore, calibrated damping elements are characterized by their very short spring travel between the stops.

[0025] According to the invention, a method for producing a chassis component according to the invention is carried out with the following steps: • Positioning the damping element in a cavity of a device for applying plastic, wherein the cavity essentially corresponds to the shape of the housing, • Supporting at least the outer part of the damping element, • Injecting a plastic material to fill the remaining cavity of the device, and • Curing of the plastic material.

[0026] This method is advantageous for the reasons described above, ie it avoids the disadvantages mentioned above that are associated with the previously usual assembly step.

[0027] According to the invention, the outer part of the damping element is supported on its outer side during the process of applying the plastic of the housing in order to absorb the forces that can occur, in particular, during application by means of an injection molding process, via the support and thus to keep them away from the damping element.

[0028] This step is based on the realization that the pressure exerted during the overmolding of the outer part of the damping element in the injection mold can cause deformation of the outer part. Particularly when using calibrated damping elements, this deformation can lead to a change or even complete misalignment of the force-spring characteristic curve set by the calibration of the damping element. Furthermore, supporting the damping element can also ensure its positioning during overmolding, i.e., it can prevent displacement or twisting of the damping element during overmolding. Such a positional deviation could lead to problems during assembly of the chassis component and to an undesirable change in the force-displacement characteristic curve of the finished chassis component.

[0029] These disadvantages or problems could be eliminated or at least reduced by injecting the plastic housing material into the injection mold at a low velocity to reduce the forces acting on the outer part of the damping element. However, this measure results in an undesirable increase in the manufacturing time of the chassis component.

[0030] Therefore, it is advantageous according to the invention to support at least the outer part of the damping element during the overmolding process in order to be able to produce the chassis component with the positioned damping element without slowing down the manufacturing process.

[0031] An embodiment and further advantages of the invention are explained in conjunction with the following figures. Fig. 1 a perspective schematic view of a damping element, Fig. 2 a perspective schematic view of a housing, Fig. 3 a perspective schematic view of a chassis component, Fig. 4a a perspective schematic view of a partial area of ​​a chassis component with a one-sided securing of the housing, Fig. 4b a detailed view of the Fig. 4a, Fig. 5a a perspective schematic view of a partial area of ​​a chassis component with a double-sided securing of the housing, Fig. 5b a detailed view of the Fig. 5a, Fig. 6a a perspective schematic view of a partial area of ​​a chassis component with a one-sided securing of the outer part, Fig. 6b a detailed view of the Fig. 6a, Fig. 7a a perspective schematic view of a partial area of ​​a chassis component with a securing of the outer part on both sides, and Fig. 7b a detailed view of the Fig. 7a.

[0032] Fig. 1 shows a perspective schematic view of a damping element 20. In this first embodiment, the damping element 20 is a cylindrical elastomer bearing 20, such as a rubber bushing; however, other shapes, such as square or oval damping elements 20, are also possible. The elastomer bearing 20 has, as its inner part 21, an inner, closed metal ring 21, through whose opening 27, which runs in the axial direction A (longitudinal axis A), an axle, shaft, or the like can be guided, inserted, and fastened. The inner metal ring 21 has a notch 22 as a positioning means 22, by means of which the inner metal ring 21 together with the damping element 20 can be secured against twisting during production. The inner metal ring 21 is positively connected, via an elastomer material 23, to an outer, closed metal ring 25, which represents the outer part 25 of the damping element 20.The outer metal ring 25 is provided in the radial direction around the elastomeric material 23 and the inner metal ring 21. For both cylindrical and rectangular damping elements 20, the radial direction is understood to be the plane perpendicular to the longitudinal axis A. The inner and / or outer metal rings 21, 25 can be made, at least in part, of aluminum or steel, for example. However, other metals are also applicable.

[0033] The representation of the Fig. 1 can also show the elastomer bearing 20 in a calibrated state. During the manufacture of the elastomer bearing 20, the rubber is introduced into the area between the inner and outer metal rings 21, 25 and vulcanized there to form the elastomer material 23. Since the rubber shrinks during vulcanization, but the metal rings 21, 25 cannot be contracted by the elastomer material 23, the elastomer material 23 forms in the radial direction under tension between the inner and outer metal rings 21, 25. The elastomer material 23 can be continuous or spaced apart by intermediate gaps. In order to reduce this manufacturing-related stress, which can reduce the service life of the elastomer bearing 20, or to set a desired course of the force path characteristic of the elastomer bearing 20, the outer metal ring 25 is therefore compressed radially after vulcanization until the desired stress is reached.In this case, the intermediate gaps in the elastomeric material 23, if present, can close.

[0034] Fig. 2 shows a perspective schematic view of a housing 30. The housing 30 is made of plastic, such as a synthetic resin, and has an outer body 31 which is reinforced by means of rib-like webs 35 in order to achieve high stability with low material usage and weight. Holes 37 are provided in the outer body 31 and / or in the webs 35 in order to be able to fasten the housing 30, for example by means of screws, bolts or the like, to a structural component of a vehicle or its chassis. Furthermore, the housing 30 has openings 33 in the axial direction B (longitudinal direction B), which are provided for receiving, for example, elastomer bearings 20.

[0035] Fig. Figure 3 shows a perspective schematic view of a chassis component 10, which has a housing 30, in whose openings 33 an elastomer bearing 20 is inserted. The longitudinal axis A of the elastomer bearing 20 and the longitudinal axis B of the openings 33 of the housing 30 lie on top of each other, ie they coincide. The openings 27 of the elastomer bearing 20 have in the illustration of Fig. 3 no axle, shaft or the like.

[0036] Fig. 4a shows a perspective schematic view of a partial area of ​​a chassis component 10 with a one-sided securing device 39 of the housing 30. Fig. 4b shows a detailed view X1 of the Fig. 4a. The inner part 20 and the surrounding plastic material of the housing 30 are in a quarter area of ​​the inner part 20 ( Fig. 4a) and the enlarged view ( Fig. 4b) is shown cut open to show the structure in more detail as well as on the back of the inner part 20 and housing 30. In particular, the Fig. 4b, that the securing means 39 of the housing 30 extends on one side around the outer part 27 of the inner part 20, ie, forms a region 39 enclosing the inner part 20. In this way, the inner part 20 is positively blocked in a direction of the axis B, ie, secured against being pushed out of the housing 30 in this direction B.

[0037] Fig. 5a shows a perspective schematic view of a partial area of ​​a chassis component 10 with a double-sided securing device 39 of the housing 30. Fig. 5b shows a detailed view of the Fig. 5a. In this embodiment, the securing means 39 is formed on both sides around the inner part 20, so that movement between the inner part 20 and the housing 30 in both directions of the axis B is positively blocked by the protrusion 39.

[0038] Fig. 6a shows a perspective schematic view of a partial area of ​​a chassis component 10 with a one-sided securing device 29 of the outer part 27. Fig. 6b shows a detailed view of the Fig. 6a. In this embodiment, the securing means 29 forms an area 29 surrounding the housing 30 on one side, so that the inner part 20 is positively blocked relative to the housing 30 in a direction of the axis B, ie is secured against being pushed out in this direction B.

[0039] Fig. 7a shows a perspective schematic view of a partial area of ​​a chassis component 10 with a double-sided securing device 29 of the outer part 27. Fig. 7b shows a detailed view of the Fig. 7a. In this embodiment, movement between the housing 30 and the inner part 20 in the direction of the axis B is blocked by a locking device 29 on each side of the outer part 27.

[0040] Conventionally, the chassis component 10 is manufactured by assembling the separately manufactured components elastomer bearing 20 and housing 30, e.g. by pressing.

[0041] According to the invention, however, the elastomer bearing 20 is introduced into the cavity of an injection mold, where it is positioned and fixed in position. The positioning and fixing of the elastomer bearing 20 can be achieved, for example, by the holding devices of the injection mold engaging the opening 27 of the elastomer bearing 20. At the same time, rotation of the elastomer bearing 20 can be prevented by engaging the notch 22. The elastomer bearing 20 can be used in both a non-calibrated and a calibrated state.

[0042] Furthermore, support devices of the injection mold engage, for example, in the area of ​​the elastomer material 23 in order to support the outer metal ring 25 outwards against the pressure of the injected plastic material and thus maintain the position of the elastomer bearing 20 during the injection molding process.

[0043] After positioning, securing, and supporting the elastomer bearing 20 in the injection mold, the injection molding material is injected into the remaining cavity of the injection mold to form the housing 30. After the plastic material has cured, the chassis component 10 can be removed from the injection mold. The outer metal ring 25 of the elastomer bearing 20 and the housing 30 are thus directly connected to one another in a form-fitting manner and formed as a single piece. List of reference symbols (part of the description) 10 chassis component 20 (calibrated) damping element or (calibrated) elastomer bearing 21 Inner part or inner metal ring 22 Positioning means or notch 23 Elastomer part or elastomeric material 25 Outer part or outer metal ring 27 Opening 29 Fuse or area surrounding the housing, one-sided or both-sided 30 housings 31 Outer body 33 openings 35 bridges 37 holes 39 Fuse or area surrounding the inner part, one-sided or both-sided A axial direction or longitudinal axis of the damping element 20 B axial direction or longitudinal axis of the openings 33 of the housing 30

Claims

[1] Method for producing a chassis component (10) for supporting a load, with at least one damping element (20), with an inner part (21), an outer part (25), and an elastomer part (23) which is provided at least partially between the inner part (21) and the outer part (25), and a housing (30) which surrounds the damping element (20) in the radial direction, wherein the housing (30) consists at least partially of plastic material and is directly connected in a form-fitting manner to the outer part (25) of the damping element (20), with the steps: Positioning the damping element (20) in a cavity of a device for applying plastic, wherein the cavity substantially corresponds to the shape of the housing (30), Supporting at least the outer part (25) of the damping element (20), Injecting a plastic material to fill the remaining cavity of the device, and Curing of the plastic material, wherein the positioning of the damping element (20) or the supporting of at least the outer part (25) comprises that the damping element (20) is positioned or supported in the cavity in a rotationally secure manner by means of a positioning means (22).

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