1. Field of the Invention
This invention relates to a hydraulically damping engine mounting with fluid-filled chambers at least partly bordered by elastic walls, and a membrane with limited excursion capability separating the membranes, with at least one passage connecting the chambers, whereby the bearing characteristic can be adjusted by changing the rigidity of a flexible wall located in one of the chambers which, at low rigidity, works against a gas volume enclosed in an intermediate space, and which at high rigidity comes into at least partial contact against a stop.
2. Background Information
Such engine mountings are disclosed, for example, by German Patent No. 34 46 725, in which there is a partition between the two chambers, and in which one of the chambers has a ring-shaped elastic membrane running along the outside wall thereof. The intermediate space formed between the elastic membrane and the rigid outer wall can be pressurized with an underpressure to achieve a high rigidity of the engine mounting. When the engine mounting is to be switched to a harder characteristic for travel, it is necessary to apply an underpressure to the intermediate space, so that the elastic wall is in direct contact against the outside wall of the engine mounting.
One disadvantage of this system is that the generation of the underpressure in the intermediate space presents problems. These problems generally arise due to the necessity of using rigid lines between the evacuation device and the mounting, as flexible feed lines were found to collapse when an underpressure was applied. Further, for reasons relating to safety, it is not possible to install bleeds or taps in the brake line. Moreover, a long feed line, even one of rigid construction, has the disadvantage that the flexible wall can only come into contact with the rigid stop after sufficient air has been been sucked out of both the intermediate chamber, as well as the underpressure line. All of these disadvantages show that the pressurization of the intermediate chamber with an underpressure has not been suitable for use in actual practice.