Reinforced upper control arm for vehicle suspension system

Abstract: An upper control arm for a vehicle suspension system having a modulus section of hollow construction for reduced weight. The modulus section of the control arm is of a stamped and welded construction thereby eliminating material weight while reducing the cost of manufacturing. The modulus section has a substantially triangular configuration with a reinforced rim flange along the high compression stress area of the control arm elbow. The reinforced rim flange improves the strength of the control arm without sacrificing the weight reduction provided by the hollow construction.

Description: This invention relates to an upper control arm for a vehicle suspension system adapted to be connected to a ball joint assembly and a pivot bar assembly and comprising an integral body having a substantially U-shaped configuration with means for receiving the ball joint assembly at the apex of said body and means for receiving the pivot bar assembly at the ends of said body. Upper control arms are routinely incorporated into the suspension systems of truck and passenger vehicles. The typical control arm is generally U-shaped with a ball joint assembly at the apex of the control arm and pivot bar bushings at the ends of the arm for mounting the control arm to a pivot bar assembly. In the past, the modulus sections between the bushings and the ball joint have been solid sections of cast iron or cast aluminum. It was believed that the traditional cast metal sections were necessary to maintain the integrity of the control arm under the stresses of the suspension system. More recently, the modulus section has been constructed of a steel forging of wire frame design. Although these control arm constructions were stong enough to withstand the stress loads they also were very heavy. In today's vehicle market every aspect of a vehicle is examined for weight reduction. US-A-2 611 625 patent discloses an independent front wheel suspension coupled as a unit to the vehicle frame and comprising a control arm presenting the features defined in the first part of independent claim 1. The arm is composed of a pair of lateral channel portions extending outwardly in a couverging manner and joined together by a wet portion. The channel portions have on both sides flanges and the outer flanges extend around the outer end portion of the web portion. This control arm may be stamped out of a single piece of sheet metal, but may not be strong enough to withstand the very high stress loads that occur during heavy use. Recent proposals for reducing the weight of the suspension system include a hollow, two-piece control arm. The square hollow bar section comprises a pair of U-shaped components nested together and double seam welded. Thus, the control arm has double side walls with single upper and lower walls. Although strong and lightweight, the double side walls are not located at the compressive stress areas of the arm where additional strength is required. Moreover, the double seam construction requires precise welding over a curving contour which has not been easy to accommodate. Nevertherless, substantial weight reduction over the solid cross-section of the prior known control arms has been accomplished. The present invention overcomes the disadvantages of the prior known control arms and this is achieved by the subject matter of claim 1. These features allow to reduce the overall weight of the control arm while maintaining strenght in key stress areas of the elbow section. The hollow triangular sections are formed through a stamping process wherein the upper apex of the modulus section incorporates a seam weld to form the triangular cross-section. For increased stiffening and reinforcement, an enlarged rim flange is formed along the welded apex seam. This rim flange along the high compression stress ares of the control arm elbow eliminates stress failures along this area and permits double plate FEA modeling resulting in additional load balancing capabilities. Other objects, features and advantages of the invention will be apparent from the following detailed description taken in connection with the accompanying drawings. The present invention will be more fully understood by reference to the following detailed description of a preferred embodiment of the present invention when read in conjunction with the accompanying drawing, in which like reference characters refer to like parts throughout the views and in which: FIGURE 1 is an elevated perspective view of a upper control arm for a vehicle suspension system embodying the present invention; and FIGURE 2 is a cross-sectional view of the control arm taken along lines 2-2 of Fig. 1. Referring to Figures 1 and 2, there is shown elevational and cross-sectional views of a control arm 10 embodying the principles of the present invention. The control arm 10 is preferably an upper control arm forming a part of a suspension system of a vehicle. As is typical of such components, the control arm 10 has a substantially U-shaped configuration with bushing apertures 12 formed at the ends of the arms 14 and a ball joint receptacle 16 formed at the apex 18 of the control arm 10. The ball joint receptacle 16 is adapted to cooperate with a ball joint assembly (not shown) and may include a ball joint housing integrally formed with the control arm 10. Typical modern control arms 10 incorporate a separate ball joint housing which is inserted into the apex 18 of the control arm 10. The bushing apertures 12 are designed to retain pipe bushings (not shown) for mating engagement with a pivot bar assembly forming a portion of the vehicle suspension system. The pivot bar typically extends through both bushing apertures 12 allowing the control arm 10 to pivot about the assembly in response to road conditions affecting the vehicle suspension system. The control arm 10 of the present invention is formed of an integral metal stamping to ensure the required structural strength for the suspension system. However, unlike the prior known control arms which incorporate a solid construction, the present invention comprises hollow modulus sections 20 for weight reduction. The control arm 10 includes modulus sections 20 along each arm 14 between the apex 18 and the bushing apertures 12. These modulus sections 20 are subject to extreme compression and tension loads and therefore must have sufficient structural strength to withstand such loads. In order to maintain the structural strength while providing substantial weight reduction, the modulus sections 20 of the control arm 10 of the present invention are provided with a hollow, substantially triangular cross-sectional configuration as best shown in Fig. 2. It has been found that this triangular configuration provides improved strength against the loads while also providing a uniform weld line over the contours of the modulus sections 20 facilitating programmable welding of the seam 22 along the modulus sections 20. The triangular modulus section 20 of the control arm 10 include a bottom wall 24 and a pair of side walls 26 brought into mutual contact to form the seam 22 at the upper (top) apex of the triangular configuration. The upper seam 22 is welded to join the side walls 26. In a preferred embodiment, a reinforcement rim flange 30 may be provided along the upper seam 22. The rim flange 30 is formed by integral extension flanges 32 of the side walls 26. The rim flange 30 provides a stiffening effect to the modulus sections 20 of the control arm 10 thereby improving structural strength. For additional strength, one or more reinforcement members 34 may be inserted within the hollow modulus sections 20. These reinforcement members 34 may be in the form of a hollow tube or a solid bar and are positioned at the high stress coordinates of the control arm 10. Thus, although the reinforcement members 34 may be inserted along the full length of the modulus sections 20 it is preferable to insert the members 34 only at the areas of greatest load thereby minimizing added weight. The reinforcement members 34 are preferably welded to the bottom wall 24 prior to bending the side walls 26 into mutual to form the triangular modulus sections 20. Thus, the present invention provides a reinforced hollow modulus section 20 of a control arm 10 while minimizing added weight. The foregoing detailed description has been given for clearness of understanding only and no unnecessary limitations should be understood therefrom as some modifications will be obvious to those skilled in the art without departing from the scope of the appended claims.

Claims: A control arm (10) for a vehicle suspension system adapted to be connected to a ball joint assembly and a pivot bar assembly, and comprising an integral body (10) having a substantially U-shaped configuration with means (16) for receiving the ball joint assembly at the apex of said body and means (12) for receiving the pivot bar assembly at the ends of said body, said integral body (10) having modulus sections (20) along each arm, characterized in that said modulus sections (20) have a hollow, substantially triangular cross-sectional configuration. The control arm (10) as defined in claim 1 and further comprising a reinforcement member (34) positioned within at least a portion of said hollow modulus section (20). The control arm (10) as defined in claim 2 wherein said reinforcement member (34) is mounted within said hollow modulus sections (20) at high load stress coordinates of said control arm (10). The control arm (10) as defined in claim 3 wherein said reinforcement member (34) is welded within said hollow modulus sections (20) at the high stress positions along said control arm (10). The control arm (10) as defined in claim 4 wherein said modulus sections (20) include an upper seam (22) formed along the top apex of said triangular modulus section (20). The control arm (10) as defined in claim 5 wherein said upper seam (22) is welded to join two sides (26) of said triangular modulus section (20) forming said top apex. The control arm (10) as defined in claim 6 wherein said triangular modulus section (20) includes a bottom wall (24), a pair of side walls (26) joined to form said seam (22) and flanges (30) integrally formed with and extending outwardly from said side walls (26), said flanges (30) forming a reinforcement rim flange adding structural strength to said modulus sections (20). The control arm (10) as defined in claim 4 wherein said reinforcement member (34) is a hollow metal tube. The control arm (10) as defined in claim 4 wherein said reinforcement member (34) is a metal bar.

Inventors: RICHART LELAND M, VRANA JOHN J, RICHART, LELAND M., VRANA, JOHN J.
Applicants: MASCOTECH INC, MASCOTECH, INC.
Application year: 1992
Main classification: B60G7
IPC codes: B60G7, F16S1