This invention relates in general to independent suspension systems for supporting a vehicle frame assembly on the wheels of a vehicle. In particular, this invention relates to an improved method for connecting a ball and socket joint to one or both of the upper and lower control arms in such an independent suspension system.
Virtually all land vehicles in common use, such as automobiles, vans, and trucks, include a frame assembly that is supported upon a plurality of ground-engaging wheels by a resilient suspension system. The structures of known vehicle frame assemblies can be divided into two general categories, namely, separate and unitized. In a typical separate vehicle frame assembly, the structural components of the body portion and the frame portion are separate and independent from one another. When assembled, the frame portion of the assembly is resiliently supported upon the vehicle wheels by the suspension system and serves as a platform upon which the body portion of the assembly and other components of the vehicle can be mounted. Separate vehicle frame assemblies of this general type are found in most older vehicles, but remain in common use today for many relatively large or specialized use modern vehicles, such as large vans, sport utility vehicles, and trucks. In a typical unitized vehicle frame assembly, the structural components of the body portion and the frame portion are combined into an integral unit which is resiliently supported upon the vehicle wheels by the suspension system. Unitized vehicle frame assemblies of this general type are found in many relatively small modern vehicles, such as automobiles and minivans.
In both separate and unitized types of vehicle frame assemblies, the suspension system resiliently supports the vehicle frame assembly on the rotatable wheels of the vehicle. One type of suspension system commonly used in both automobiles and trucks is an independent suspension system. In an independent suspension system, the vehicle frame assembly is supported individually upon each of the wheels of the vehicle such that each of the wheels can move upwardly and downwardly relative to the vehicle frame assembly independently of the other wheels. Thus, when a bump or a depression in the road upon which the vehicle is operated is encountered by one of the wheels, the other wheels are not moved upwardly and downwardly in response thereto. As a result, the independent suspension system provides a relatively smooth ride.
A typical structure for an independent suspension system includes a lower control arm and, in some instances, an upper control arm for each wheel of the vehicle. The upper and lower control arms are typically V-shaped, each having a pair of inner ends that are connected to the vehicle frame structure for pivoting movement in a generally vertical plane and an intermediate outer portion. The outer portions of the upper control arm and the lower control arm are connected through respective ball and socket joints to the upper and lower ends of a steering knuckle. A wheel spindle extends outwardly from the steering knuckle between the upper and lower ends thereof, and a hub and wheel assembly is mounted on the outer end of the wheel spindle. The pivoting connections of the upper and lower control arms to the vehicle frame assembly allow the wheels to move upwardly and downwardly, while maintaining the rotational axis of the wheel generally parallel with the road upon which the vehicle is operated. The two ball and socket joints permit rotational movement of the steering knuckle and wheel spindle relative to the vehicle frame assembly, while accommodating a limited amount of angular movement between the upper and lower ends of the steering knuckle and the respective upper and lower control arms connected thereto during the vertical pivoting movement.
As mentioned above, the outer portions of the upper and lower control arms are connected to respective ball and socket joints. Traditionally, this connection has been accomplished forming an aperture through the outer portion of the control arm and inserting the socket portion of the ball and socket joint through this aperture. A circumferential flange provided on the socket portion of the ball and socket joint abuts the control arm to properly position the ball and socket joint and to bear the load of the vehicle on the associated wheel. A number of methods are known in the art for retaining the socket portion of the ball and socket joint in the control arm aperture. In some instances, the socket portion is sized to be press fit within the aperture. In other instances, a plurality of rivets or other mechanical fasteners extend through respective apertures formed through the circumferential flange and the control arm.
Although known retaining methods have been effective, it has been found that in some instances, the control arm may be formed having a configuration that provides such a small physical space that the use of traditional rivets and other mechanical fasteners is difficult at best. Also, it has been found that the apertures formed through the control arm to accommodate such rivets and other mechanical fasteners may introduce undesirable weaknesses therein. Thus, it would be desirable to provide an improved method for connecting a ball and socket joint to a control arm in a vehicle suspension system that avoids these problems.