GB2161241A

GB2161241A - A hydraulically damped resilient mounting

Info

Publication number: GB2161241A
Application number: GB08512783A
Authority: GB
Inventors: Jurgen Heitzig; Gunter Eberhard
Original assignee: Continental Gummi Werke AG
Current assignee: Continental AG
Priority date: 1984-05-28
Filing date: 1985-05-21
Publication date: 1986-01-08
Also published as: DE3419851A1; ES286798U; SE8502586D0; FR2564929A1; SE8502586L; IT1185577B; GB8512783D0; ES286798Y; JPS6159035A; IT8520905A0

Abstract

In a hydraulically damped resilient mounting of the type where an elastomeric spring 2 and a diaphragm 4 define two liquid-filled chamber 8, 9 which communicate via a throttle 17, a chamber 10 on the other side of the diaphragm (which would normally be at atmospheric pressure) can be subjected to a reduced pressure when desired. This causes the diaphragm 4 to deflect to the dotted line position which induces cavitation in the liquid. This renders the throttle 17 and therefore the hydraulic damper ineffective, thus removing a source of undesirable noise. When the mounting is used to mount a vehicle engine, vacuum is supplied from the manifold either selectively or automatically in response to sensed parameters. <IMAGE>

Description

SPECIFICATION A hydraulically damped mounting The present invention relates to hydraulically damped mountings, more especially for the driving motor in motor vehicles, said mounting comprising a cup-shaped housing which is sealed, at its upper circumferential edge when viewed in the loading direction, by a resilient rubber member and is sealed, in its lower region, by a flexible diaphragm which is held in position at a distance from the base of said housing, and said mounting comprising a throttle device in the housing interior between the resilient member and the diaphragm, said housing interior being filled entirely with a damping fluid.

In engine mountings of this type, the vibrations caused by shocks during travel and also by the imbalances in the engine are damped by the throttled overflow of damping fluid through the throttling device within predetermined frequency range and rapidly absorbed. If, on the one hand, therefore, the travelling comfort is considerably increased, the throttling device, on the other hand, also contributes again towards transmission of noises, and such transmission is greater than with undamped mountings. Accordingly, it is an object of the pres ent invention to combine the desired damping properties of resilient mountings with the acoustic blocking action of conventional, undamped mount ings.

According to the present invention there is provided a hydraulically damped resilient mounting, more especially for the driving motor in motor ve hicles, said mounting comprising a cup-shaped housing which is sealed, at its upper circumferential edge when viewed in the loading direction, by a resilient rubber member and is sealed, in its lower region, by a flexible diaphragm which is held in position at a distance from the base of said housing, and said mounting also comprising a throttle device in the housing interior between the resilient member and the diaphragm, said housing interior being filled entirely with a damping fluid, in which, on its end remote from the damping fluid, the diaphragm is capable of being acted upon by a reduced pressure -relative to the outside atmosphere.

According to an arrangement of the present in vention, the chamber, sealed from the outside, between the housing base and the diaphragm is provided with a connection member which is alter nately connectable to a source of reduced pressure and to the outside atmosphere.

By using surprisingly simple means,the present invention permits the damping of the mounting to be selectively switched-on or made ineffective. Un der normal circumstances -that is to say, when the diaphragm becomes deformed counter to the at mospheric pressure - the throttling device functions in an unhindered manner, so that the full damping effect is achieved to the prescribed extent. If reduced pressure is fed to the underside of the diaphragm, however, the diaphragm tends to become deformed in the direction towards the housing base. The resultant reduced, static pressure of the damping fluid causes the internal binding forces to be similarly reduced, and foam and pinholes are thereby formed; so, in practical terms, the throttling device becomes inoperative. In this state, the mounting operates with the considerably lower noise level of an undamped resilient mounting.

When the present invention is preferably applied to engine mountings of motor vehicles, there is no problem in supplying reduced pressure, because such reduced pressure is always available to an adequate extent at the induction manifold of the engine. The diaphragm loading can be switched between reduced pressure and atmospheric pressure at will by the driver. This is achieved, for example, by means of a solenoid valve which is to be actuated from the instrument panel or, however, such switching may also be effected automatically in dependence upon predetermined parameters of the mounting system, possibly via an on-board computer.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawing, in which the single Figure is a cross-sectional view through an engine mounting.

The main component parts of the illustrated engine mounting include a cup-shaped housing 1 and an upper bearing insert 3 which is supported on said housing 1 via a hollow-conical, resilient rubber member 2 which simultaneously forms the upper seal for the housing 1 which is produced from a piece of moulded sheet metal. A flexible rubber diaphragm 4 is sealingly clamped in position in a flange-like edging beneath the resilient member 2, said diaphragm 4 being spaced from said resilient member and also from the housing base. The mounting may be secured to a portion of a vehicle body (not shown) by means of a headed screw 5 attached to the base of the housing 1, while the bearing insert 3 serves to receive an engine retaining means (also not shown more fully) and, for this purpose, said insert 3 is provided with a stud bolt 6.A dividing wall 7, which is clamped to the diaphragm 4 in the edge region of the housing 1, divides the externally sealed housing interior between the resilient member 2 and the diaphragm 4 into an upper chamber 8 and a lower chamber 9 which, as indicated by dashed lines in the drawing, are both filled entirely with a damping fluid and are both constantly interconnected via a throttle bore 17 which extends through the dividing wall 7.

The shape of the resilient member 2 changes as a result of dynamic loadings, and such deformations produce reciprocal displacements in a column of fluid between two chambers 8 and 9 through the throttle bore 17. In turn, such displacements produce reciprocal movements of the diaphragm 4 which extends with an edge bead along the internal wall of the housing 1. This mode of operation for the mounting thus far described is known per se.

In the arrangement according to the present invention, the working chamber 10 is formed be tween the diaphragm 4 and the fully continuous base of the housing 1 and is provided with a connection member 25 via a bore 15 formed in the headed screw 5, said connection member 25 being suitable for the attachment thereto of a pipe or hose. This arrangement permits reduced pressure or atmospheric pressure to be selectively introduced into the working chamber 10, as shown by the arrow "vac/at". While the diaphragm 4 actuates damping in the described manner counter to atmospheric pressure, it becomes deformed by the influence of reduced pressure in the working chamber 10 (as shown by the broken lines) to such an extent that foam portions and vapour bubbles develop in the damping fluid in the chambers 8 and 9. In practical terms, this arrangement eliminates the effectiveness of the whole damping device.

Claims

1. A hydraulically damped resilient mounting, more especially for the driving motor in motor vehicles, said mounting comprising a cup-shaped housing which is sealed, at its upper circumferential edge when viewed in the loading direction, by a resilient rubber member and is sealed, in its lower region, by a flexible diaphragm which is held in position at a distance from the base of said housing, and said mounting also comprising a throttle device in the housing interior between the resilient member and the diaphragm, said housing interior being filled entirely with a damping fluid, in which, on its end remote from the damping fluid, the diaphragm is capable of being acted upon by a reduced pressure -relative to the outside atmosphere.

2. A mounting as claimed in claim 1, in which the chamber, sealed from the outside, between the housing base and the diaphragm is provided with a connection member which is alternately connectable to a source of reduced pressure and to the outside atmosphere.

3. A hydraulically damped resilient mounting substantially as hereinbefore described with reference to the accompanying drawing.