The present invention relates to the field of suspension thrust bearing devices used in particular on motor vehicles in the suspension struts of the steered road wheels.
The invention relates more particularly to a suspension thrust bearing comprising a top ring and a bottom ring between which are positioned rolling elements, for example balls or rollers. The top and bottom rings are generally mounted in contact with bottom and top bearing or support pieces, such as covers or cups. The top and bottom cups form a housing for the rings of the rolling bearing and provide the interface between said rings and the neighbouring elements.
A suspension thrust bearing is positioned in the top part of the suspension strut between the bodywork of the vehicle and a suspension spring. The spring is fitted around a damping piston rod, the end of which is linked to the bodywork of the vehicle through an elastic block that filters the vibrations. The suspension spring axially bears, directly or indirectly, on the bottom cup. The top cup is fixed relative to the bodywork of the vehicle.
The suspension thrust bearing makes it possible to transmit axial forces between the suspension spring and the bodywork of the vehicle, while allowing a rotation movement between the bottom cup and the filtering elastic block. This relative angular movement derives from a steer angle of the steered road wheels of the vehicle and/or the compression of the suspension spring.
A suspension thrust bearing is known from the document EP-B1-1 445 129, that is provided with a bottom support cover and a rolling bearing mounted to bear against the latter. The support cover is made of synthetic material and comprises an axial centring surface for a suspension spring which is prolonged, at its top end, by a radial surface forming a stop for the end of said spring.
In the embodiment illustrated in FIGS. 2 and 4, an intermediate bearing cup is positioned between the suspension spring and the support cover in order to obtain a good distribution of the load applied by the spring and substantially reduce the risks of cracking of the support cover.
In operation, the intermediate bearing cup is exposed to water splashes, which means that anti-corrosion surface treatments such as catophoresis must be used. However, these treatments are relatively costly and their implementation is a polluting factor.
To overcome this drawback, the patent application FR-A1-2 857 906 recommends to embed, inside the bottom support cover, a metal stiffening insert. The use of an additional, separate bearing cup is thus avoided.
However, the suspension thrust bearing of this document presents the drawback of providing only a single narrow passage between a top cover and the bottom support cover supporting the rolling bearing to provide the seal for the bearing.
Thus, in certain conditions, for example when the vehicle is running on a flooded road or even when cleaning the vehicle with a high pressure water jet, water can infiltrate into the rolling bearing with harmful consequences on the life of the rolling bearing.