GB2152182A

GB2152182A - Hydraulically damped two-chamber bearing structure

Info

Publication number: GB2152182A
Application number: GB08429471A
Authority: GB
Inventors: Rolf Von Sivers
Original assignee: Dr Ing HCF Porsche AG
Current assignee: Dr Ing HCF Porsche AG
Priority date: 1983-11-23
Filing date: 1984-11-22
Publication date: 1985-07-31
Also published as: GB8429471D0; IT8423466A0; DE3342300A1; FR2555272A1; IT8423466A1; FR2555272B1; JPS60136637A; IT1177120B; DE3342300C2; GB2152182B

Abstract

A hydraulically damped two-chamber bearing structure for motor vehicles in which the two chambers (2, 3) are hydraulically connected with each other by way of an intermediate plate (4) provided with a throttle opening 17, 16, 18 and fixedly held in the bearing housing (7, 10). One chamber (3) is delimited by a supporting rubber element (9) connected with a bearing core (20), which is prestressed opposite its main load direction and has a normal position (as shown) displacing the damping fluid from the first chamber (3) into the second chamber (2). The second chamber (2) is constructed as a resilient expansion container for the accommodation of the damping fluid from the first chamber (3), which is under the pressure of the prestress of the rubber element (9). <IMAGE>

Description

SPECIFICATION Hydraulically damped two-chamber bearing structure The present invention relates to a hydraulically damped two-chamber bearing structure for a motor vehicle aggregate bearing support, in which the two chambers are hydraulically connected with each other by way of an intermediate plate held fixedly in the bearing housing and provided with a throttle opening.

Bearing structures with hydraulic damping are known in the prior art for shock and vibration damping between two constructional elements limitedly movable relative to one antoher (DE OS 30 27 742). These bearing structures include two chambers which are hydraulically connected with each other by means of a throttle. Damping takes place by a fluid interchange.

In a three point suspension of a drive aggregate constructed in the manner of a transaxle, in which the forward drive unit is supported by two bearings and the rear unit by a single bearing, a special bearing matched to these conditions is necessary for the rear bearing. A complicated construction is required with the prior art bearing for achieving a bearing matched to these conditions of the drive aggregate constructed in the manner of a transaxle, particularly as not only a damping should be attainable in the vertical direction but also in radial directions.

The object of the present invention is to provide a two-chamber bearing structure which effectively dampens large vibrational deflections, acts in a body sound-insulating manner and has different stiffnesses in the radial and axial direction.

The present invention consists in a hydraulically damped two-chamber bearing structure for a motor vehicle aggregate bearing, comprising two chambers hydraulically connected with each other by way of an intermediate plate provided with a throttle opening and fixedly held in a bearing housing, one chamber being delimited by a supporting rubber element connected with a bearing core, wherein the rubber element is prestressed opposite its main load direction and has a normal position displacing the damping fluid from the first chamber into the second chamber, said first chamber being constructed as a resilient expansion container for the reception of damping fluid displaced from the second chamber, which is under the pressure of the prestress of the rubber element.

In the two-chamber bearing according to the present invention, a tensional bearing construction is necessary with a drive aggregate in the form of a transaxle by reason of its use as sole rear bearing, which is arranged above the aggregate. By means of such a bearing, on the one hand, a far-reaching acoustic separation between the aggregate and body is to be achieved, and on the other hand, also large vibrational movements are to be able to be effectively dampened, whereby the bearing is of different stiffness in the radial and axial direction. With larger vibrational deflections in the main load direction (tension) as well as in radial directions, abutments are provided which are integrated into the bearing.

The rubber element is so dimensioned that in case of a supporting function in the tensional direction it assumes a maximum bodysound-insulation function (dammping). Therebeyond, the element is used for the inherent material damping. In addition to this damping, a further hydraulic damping takes place by fluid exchange in a throttle bore of the partition plate.

A throttle channel in the intermediate plate which is constructed ring-shaped in a special manner, effects a particularly high damping of low frequency movements, the ratio of diameter to channel length is smaller than 0.1.

In order that the desired characteristic of the rubber element is not influenced disadvantageously by stresses. a pot-shaped outer bearing housing is passed, during the assembly of the bearing, over the inner housing connected with the rubber element, only when it is completely installed at the aggregate.

In the accompanying drawings: Figure 1 is a cross-sectional view through a two-chamber in accordance with the present invention in the non-loaded condition; and Figure 2 is a cross-sectional view through the two-chamber bearing of Figure 1 in the loaded condition.

Referring now to the drawings the bearing comprises an upper chamber 2 and a lower chamber 3 which are separated by an intermediate or partition plate 4 by means of a throttle 5. The upper chamber 2 is formed by an expansion container 6 of resilient material and is arranged in an upper bearing housing part 7.

The lower chamber 3 is formed by the intermediate plate 4, an upper boundary surface 8 of a rubber element 9 and an inner housing 10 receiving the element 9.

The inner housing 10 is received by a lower bearing housing part 11 which is connected with the upper bearing housing part 7.

The rubber element 9 is prestressed opposite its main load direction 12, in such a manner that the hydraulic fluid is displaced from the chamber 3 into the chamber 2 and fills the expansion container 6, as is illustrated in Figure 1, in the normal rest position of the rubber element.

The intermediate plate 4 includes an upper part and a lower part 1 4 connected with the upper part, which form therebetween a ringshaped channel 1 6 with an inflow opening 1 7 and the outflow opening 18.

An abutment 1 9 facing the rubber element 9 is provided at the intermediate plate 4 which is constructed rigidly; the abutment 1 9 limits an immersing movement of the rubber element 9 into the housing 11.

A frusto-conically solid bearing core 20 which is connected with the rubber element 9, is arranged concentrically within the rubber element 9. This bearing core 20 includes at its end face a bolt 21 which alone carries the drive aggregate, for example, at the height of a differential 22.

The rubber element 9 is preferably of frusto-conical shape, whereby the outer boundary surface 24 extends at the same direction a to the inner boundary surface 24a and thus to the circumferential surface 23 of the bearing core 20. It is achieved thereby that the existing rubber volume is stressed uniformly and partakes in equal parts in the functions to be effected.

The volume of the bearing core 20 amounts to about 1/3 to about 1/4 of the volume of the rubber element 9 whereby an optimum damping is achieved by way of the rubber element because the entire volume of the rubber is utilized for the dissipating work.

For limiting the movement of the rubber element 9 in the axial and radial directions, further abutments 25 and 26 are provided in addition to the compression abutment 1 9.

The abutment 25 for the axial limitation is formed by the lower boundary surface 27 of the rubber element 9 which is arranged facing the bottom 28 of the outer bearing housing part 11. The other radial abutment 26 is formed by the neck 29 of the rubber element 9 which projects through an opening in the bottom 28 of the lower bearing housing part 11 and is arranged adjacent an opening edge 30 of the housing.

The rubber element 9 is vulcanized onto the inner housing 10 and includes at its end a flange 31, on which the intermediate plate 4 is supported under interposition of a resilient element 32 and on which the expansion container 6 is supported circumferentially. The expansion container 6, the intermediate plate 4 and the inner housing 10 are held circumferentially clamped within an annular groove 33 formed by the upper bearing housing part 7. A connection of the upper bearing housing part 7 with the lower bearing housing part 11 then takes place by way of a connecting member 34 on the side of the body, which is connected with a flange 35 of the lower bearing housing part 11 and extends over the upper bearing housing part 7 retaining the same within the area of the annular groove 33.

As is shown in greater detail in Figure 2 in comparison to the position of the rubber element according to Figure 1, the rubber element 9 is axially displaced in the direction of the arrow 1 2. A part of the fluid has passed in this position from the chamber 2 by way of the throttle 5 in the intermediate plate 4 into the other chamber 3, whereby the expansion container 6 has slightly contracted and with the movement of the differential 22 in the main load direction 1 2 a reduction of the liquid volume of the upper chamber and an increase of the liquid volume of the lower chamber 3 takes place by way of the throttle 5. During the initial outward spring deflection, the hydraulic fluid which is under excess pressure in the chamber 2, enters into the chamber 3 throttled through the relatively narrow inflow opening as well as through the channel 1 6. After the initial outward spring deflection, when the excess pressure in the chamber has been decreased, the hydraulic fluid is drawn from the chamber 2 into the chamber 3 by the vacuum. The resilient damping which is produced by the rubber element 9 is thus additionally assisted hydraulically.

For changing the radial stiffness respectively resilience of the bearing, apertures 36 are provided in the rubber element.

Claims

1. a hydraulically damped two-chamber bearing structure for a motor vehicle aggregate bearing, comprising two chambers hydraulically connected with each other by way of an intermediate plate provided with a throttle opening and fixedly held in a bearing housing, one chamber being delimited by a supporting rubber element connected with a bearing core, wherein the rubber element is prestressed opposite its main load direction and has a normal position displacing the damping fluid from the first chamber into the second chamber, said first chamber being constructed as a resilient expansion container for the reception of damping fluid displaced from the second chamber, which is under the pressure of the prestress of the rubber element.

2. A bearing structure according to claim 1, wherein the intermediate plate includes an upper part and a lower part connected with the upper part, an annular channel for the fluid passage being formed between the upper part and lower parts, said channel being provided with at least one inflow opening and at least one outflow opening into the respective chambers.

3. A bearing structure according to claim 1 or 2, wherein the intermediate plate includes a concentric abutment for the rubber element.

4. A bearing structure according to any of claims 1 to 3, wherein the rubber element has a frusto-conical outer surface for connection with a pot-shaped bearing housing.

5. A bearing structure according to claim 4, wherein the bearing core is of frusto-conical shape and arranged concentrically in the rubber element, wherein the inner surface of the rubber element connected with the bearing core extending at substantially the same distance to the outer surface connected with the bearing housing.

6. A bearing structure according to claim 4 or 5, wherein the volume of the bearing core is about one-third to one-fourth of the volume of the rubber element.

7. A structure according to any of the preceding claims, wherein a lower boundary surface of the rubber element forms a tensional limit abutment facing the housing bottom.

8. A bearing structure according to any of the preceding claims, wherein a neck of the rubber element projects through an opening in the lower bearing housing part and forms a radial boundary abutment adjacent thereto.

9. A bearing structure according to any of the preceding claims, wherein the rubber element is held in an inner housing received by the lower bearing housing part which, together with the intermediate plate and the expansion container, is held circumferentailly in an annular groove formed by two flanges of an upper bearing housing part.

1 0. A bearing structure according to claim 9, wherein the rubber element held in the inner hosuing is received free of stress by the lower bearing housing part.

11. A hydraulically damped two-chamber bearing structure substantially as described with reference to. and as illustrated in, the accompanying drawings.