FORM 2
THE PATENT ACT 1970 (39 of 1970)
The Patents Rules, 2003 COMPLETE SPECIFICATION
(See Section 10, and rule 13)
1. TITLE OF INVENTION
CONTROL ARM, IN PARTICULAR A TRANSVERSE CONTROL ARM, FOR A
VEHICLE WHEEL SUSPENSION
2. APPLICANT(S)

a) Name
b) Nationality
c) Address

ZF FRIEDRICHSHAFEN AG GERMAN Company 88038 FRIEDRICHSHAFEN GERMANY

3. PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the invention and the manner in which it is to be performed : -

Description
The invention relates to a control arm, in particular a transverse control arm, for a motor vehicle wheel suspension, comprising at least two elongate hollow body components and at least one substantially plate-shaped connection element fastened to the hollow bodies.
Control arms for motor vehicle wheel suspensions are known in different designs in the prior art. They may take the form of shell-like components, wherein such control arms as a rule comprise two shell components, which are formed from sheet metal and welded or riveted to one another at their outer edges.
Control arms of the initially described generic type are moreover known, in which two hollow body components, which as a rule are configured as closed profiles, to the outside of which a metal connection sheet is welded to form the overall body. The drawback of such a control arm structure is that, first of all, the components that are to be connected to one another have to be manufactured with a relatively close tolerance so that the total external dimensions of the finished control arm have the required values particularly in view of necessary chassis- and body connections.
Control arms of this type moreover have the drawback that the planar moment of inertia of the overall structure may be adapted to specific boundary conditions only by varying the ratios of dimensions, for example of the hollow body components and the thickness of the connection web.
The object of the present invention is therefore further to develop a control arm of the initially described generic type in a way that makes it possible, on the one hand, to bring about an easier tolerance compensation of the components to be connected to one another and, moreover, to adapt the component structure to different requirements with regard to planar moments of inertia.
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This object is achieved according to the invention by the technical teaching described in the characterizing portion of claim 1.
What is central to the present invention is that the hollow body components have at least one opening extending in the component longitudinal axis for receiving one of the end regions of the connection element, and that the end region of the connection element to be connected to a hollow body profile is inserted into the interior of the hollow body component in order to achieve an increased and predetermined planar moment of inertia.
This design according to the invention, first of all, by virtue of a differing depth of insertion of the respective end regions of the connection element into the openings of the respective hollow body components permits an optionally required tolerance compensation with regard to the external dimensions of the control arm to be manufactured and, at the same time, by virtue of the depth dimension of the inserted end regions it is possible to bring about a significant change of the planar moment of inertia of the overall structure.
Further advantageous developments of the subject matter of the invention arise from the features of the sub-claims.
With regard to a variation of the planar moment of inertia, it has proved particularly advantageous for the end regions of the connection element that are inserted into the interior of the hollow body components to be provided with at least one bend inside the interior. By means of one or more bends it is optionally possible to introduce more material of the connection element inside the interior of the hollow body components, this in turn influencing the magnitude of the planar moments of inertia.
It has proved an advantageous technique for connection of the individual parts of the control arm to weld hollow body components and connection webs to one another in the region of the hollow body opening, thereby simultaneously bringing
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about a sealing of the hollow body components. The joining point in this case is advantageously situated not immediately adjacent to the outside of the components where possibly particularly high stresses occur.
There now follows a detailed description of several development variants of the subject matter of the invention with reference to the accompanying drawings.
These drawings show:
Figures 1 to 4 cross-sectional views of constructional variants of control arms according to the invention of different dimensions.
The control arm of a vehicle wheel suspension that is illustrated in cross section in Figure 1 substantially comprises a hollow body component 1, a hollow body component 2, and a plate-shaped connection element 3 disposed between the two hollow body components 1 and 2. The hollow body components 1 and 2 are of a substantially rectangular design in cross section and have in each case at a side wall slot-shaped openings 4, which are oriented in the direction of the central longitudinal axis of the hollow body components 1 and 2. The width of the openings 4 is so dimensioned that it corresponds approximately to the thickness of the connection element 3. The connection element 3 is of a substantially plate-shaped design.
It is evident from Figure 1 that two end regions 7 of the connection element 3 have been inserted through the openings 4 of the hollow body components 1 and 2, with the result that the corresponding end regions 7 are situated inside the interior 6 of the hollow body components 1 and 2. This structure according to the invention has substantially two advantages. Firstly, by the insertion of the end regions 7 of the connection element 3 it is possible to bring about a specific tolerance compensation with regard to the total external dimensions of the control arm. What is more, depending on the size of the cross sections of the hollow body components 1 and 2 it
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is possible optionally to realize control arms of differing overall size by inserting the end regions 7 to a differing extent into the interiors 6 of the hollow body components 1,2. A further positive effect of the design is the possibility of being able to influence the planar moment of inertia of the overall structure of the control arm by insertion of the end regions 7. Tests have demonstrated that, compared to a clear interior 7 of the hollow body components 1, 2, the planar moment of inertia of the construction of Figure 1 may be increased by ca. 20%. If a specific planar moment of inertia is required, then by virtue of insertion of the connection element 3 into the respective interiors 7 of the hollow body components 1, 2 a precisely predetermined planar moment of inertia may be achieved.
In Figure 2 a construction of a control arm for a motor vehicle wheel suspension is shown, which as in Figure 1 substantially comprises two hollow body components 1, 2 as well as a connection element 3 connected to the hollow body component. A fundamental design difference between the various constructional variants Ues in the fact that the end regions 7 of the connection element 3, which project in each case through the opening 4 inside the hollow body components 1 and 2 into the interiors 6 of the respective components, are each provided with two bends 8 and 9. By means of these bends the mass of the end region 7 of the connection element 3, which are disposed inside the interior 6 of the respective hollow body components 1 and 2, may be additionally increased compared to the construction of Figure 1. This results computationally in an increase of the planar moment of inertia compared to a clear interior 6 of more than 60%. The connection of the respective connection element 3 to the hollow body components 1 and 2 is realized in both constructional variants by means of a welded connection. The welded connection is effected here, as may be seen from Figures 1 and 2, by means of weld seams 5 that are disposed directly adjacent to the respective opening 4 of the hollow body components 1 and 2.
The control arm illustrated in Figure 3 has two differently shaped hollow profiles 1 and 11 as well as a connection element 3 disposed between them. The hollow body component 1 corresponds substantially to the design also provided in Figures 1 and
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2 for the hollow body components 1 and 2 illustrated there. The hollow body component 1 of Figure 3 however has in the region of the opening 4 two outwardly projecting flanges 12, which form between them the opening gap, through which the end region 7 of the connection element 3 is inserted. Designing the opening region with the illustrated flange 12 may be advantageous when the hollow body component 1 is to be connected for example by spot welding to the connection element 3. The location of the spot welding is indicated by a dash-dot line in Figure 3.
The further hollow body component 11 in Figure 3, in contrast to the hollow body component 1, is of a substantially U-shaped design, thereby producing in this case a wider opening 13. Into the opening 13 the end region 7 of the connection element 3 is inserted to such an extent that it comes to lie with its free end abutting the rear wall of the hollow body component 11. The free end of the connection element 3 is in this case bent substantially at right angles, thereby resulting in a widening of the contact surface between the connection element 3 and the wall of the hollow body component 11. In this region, the two components of the transverse control arm are connected to one another likewise by means of spot welding, the location of which is indicated by the dash-dot line.
In Figure 4 a further development variant of a control arm is illustrated in cross section, in which both hollow body components 11 take the form of U-shaped profiles. Into the resulting openings the respective end regions 7 of the connection element 13 are inserted. In the illustrated embodiment, these end regions are each altered in shape by means of the bends 8 and 9 in such a way that for the connection element 13 a shape arises, which together with the hollow body components 11 realizes a closed form of the end regions of the control arm.
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List of reference characters
1 hollow body component
2 hollow body component
3 connection element
4 opening
5 weld seam
6 interior
7 end region
8 bend
9 bend
10 through-hole
11 hollow body component
12 flange
13 connection element

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WE CLAIM:
1. Control arm, in particular a transverse control arm, for a motor vehicle wheel
suspension, comprising at least two elongate hollow body components and at
least one substantially plate-shaped connection element fastened to the hollow
bodies,
characterized in that
the hollow body components (1, 2, 11) have at least one opening (4) extending in the component longitudinal axis for receiving one of the end regions (7) of the connection element (3), and that the end regions (7) of the connection element (3) are inserted into the interior of the hollow body component (1, 2).
2. Control arm according to claim 1,
characterized in that
the end regions (7) of the connection element (3) that are inserted into the interior of the hollow body component (1, 2) have at least one bend (8, 9) inside the interior (6).
3. Control arm according to one of claims 1 or 2,
characterized in that
the hollow body component (1, 2) and connection web (3) are welded to one another in the region of the hollow body opening (4).
4. Control arm according to one of claims 1 to 3,
characterized in that
the connection element (3) have through-openings (10) in the sub-regions that are not situated inside an interior (6) of a hollow body component (1, 2,11).
Dated this 2nd day of July, 2007

ABSTRACT
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A control arm, in particular a transverse control arm, for a motor vehicle wheel suspension, comprising at least two elongate hollow body components and at least one substantially plate-shaped connection element fastened to the hollow bodies, is proposed, in which according to the invention the hollow body components (1, 2,) have at least one opening (4) extending in the component longitudinal axis for receiving one of the end regions (7) of the connection element and the end regions (7) of the connection element (3) are inserted into the interior of the hollow body component (1, 2).