GB2129910A

GB2129910A - Hydraulically damped elastomeric mounting

Info

Publication number: GB2129910A
Application number: GB08322944A
Authority: GB
Inventors: Jurgen Heitzig; Dr Gunter Eberhard
Original assignee: Continental Gummi Werke AG
Current assignee: Continental AG
Priority date: 1982-09-09
Filing date: 1983-08-26
Publication date: 1984-05-23
Also published as: ES274264Y; DE3233456C2; IT8322768A0; GB2129910B; FR2533007B1; IT1166944B; SE448569B; FR2533007A1; ES274264U; GB8322944D0; DE3233456A1; SE8304636D0; SE8304636L

Abstract

Elastic engine mountings having a ring-shaped rubber spring member 3 which takes up static and dynamic loads and being equipped with a damping disc 8 immersed in a damping fluid 6 in order to provide hydraulic damping have been proposed. In accordance with the invention, the damping disc 8 is movably mounted with axial play between spherical or ball-shaped buffer surfaces on a rod 4 and is provided with holes (81) through which the damping fluid can flow in the vicinity of the buffer surfaces. Low amplitude movements of the rod are not transmitted to the disc 8 and are therefore undamped. Larger amplitude movements are transmitted to the disc 8, but impact noise is minimised by the buffer surfaces and the flow resistance afforded by the holes (81). <IMAGE>

Description

SPECIFICATION Hydraulically damped elastic mounting The present invention relates to hydraulically damped elastic mountings, particularly for the engines of motor vehicles, having a ring-shaped rubber spring member which seals off a potshaped housing containing the damping fluid and includes a damping disc immersed in a damping fluid mounted on a rigid connecting member which passes centrally through the spring member with a tight fit.

In known mountings of this type, (e.g.

according to DOS 2,712,641), the damping disc is connected to a connecting member which takes up the engine load directly by means of an elastically deformable transmission member. All experience shows that connections of this type and similar continuous connections between the damping disc and the connecting member in practice produce undesirable noise in the mountings. For improved acoustic behaviour of the mounting, however, it is desirable that the damping disc should not make contact up to a limiting amplitude of movement of the spring and entirely avoid the need for damping in this range of vibrations.

Accordingly it is an object of the present invention to provide freedom of movement for the damping disc which is independent of the movement of the spring of the mounting in the lower range of vibrational amplitudes and thus to ensure the necessary acoustic decoupling, while at the same time avoiding the hazard of undesirable impact noise resulting therefrom.

According to the present invention there is provided a hydraulically damped elastic mounting, particularly for the engine of a motor vehicle, includes a ring-shaped rubber spring member which seals a pot-shaped housing containing damping fluid and carries a damping disc immersed in a damping fluid on a rigid connecting member which passes centrally through the spring member forming a tight fit therewith, in which the damping disc, manufactured from a rigid material, is located movably in an axial direction on the connection member between spherical or ballshaped buffer surfaces which arch back outwards and is provided with holes for the flow of damping fluid in the vicinity of the contact surface.

In a practical embodiment of the concept of the invention the damping disc can be applied to the shaft of an axially movable interlocking set screw, that is one constructed with radial contact on all sides, which is inserted into the connecting member, wherein in accordance with a further important subsidiary characteristic of the invention the holes for the passage of fluid are constructed as open recesses behind the hole distributed at mutual angular spacings around the periphery of the central hole accepting the shaft of the set screw and the head of the set screw has a substantially identical diameter to that of the cylindrical connecting member and the surface of which facing the damping disc is constructed in a spherical or ball shape in the same way as the frontal surface of the connecting member.

The invention performs the specified task by surprisingly simple means. The damping disc which is applied to the shaft of the set screw in an interlocking way without any possibility of deviation in a radial direction has the limited axial play in both directions necessary for the desired acoustic decoupling with the possibility that the amount of free movement, and thus the range of undamped vibration, can be altered by appropriate adjustment of the supporting set screw in accordance with the conditions obtaining or the initial conditions. The resulting increased hazard of impacts, rattling and impact with the damping disc is avoided however by the special design and arrangement of the flow passages in association with the spherical or ball-shaped construction of the buffer surfaces.In association with the parts which move in relation to each other the flow and displacement forces in the closing stage of the free movement increase sharply in such a way that direct impact between the metal surfaces is always and under all circumstances reliably prevented. The app!ication of known noisedamping cushioning pads with the disadvantage of greater complexity of construction and greater length can henceforth be avoided.

The present invention will be further illustrated, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a longitudinal sectional view of a hydraulically damped elastic engine mounting; and Fig. 1 a is a plan view of the damping disc of the mounting.

The mounting illustrated consists of a potshaped housing 2, made of sheet steel, light metal or any other metallic material, which is provided with bent over securing flanges 21. A ring-shaped rubber spring member 3 is pressed and locked by means of its shape into the upper region of the housing 2 and at the same time forms the upper seal. A metal connecting member 4 passes centrally through the fuil length of the spring member 3, the arrangement being such that connecting member 4 is only tightly fitting in the upper portion of spring member 3, the greater part of the length of the connecting member 4 being free to move relative thereto with radial play. The housing 2 can be folled with a suitable high viscosity damping fluid 6 by means of a filling hole which can be seaied by a stopper 5.

In the mounted condition, the mounting is secured to a load-bearing member of a motor vehicle (not shown) on the housing side by means of flanges 21, while the supported engine rests directly on a securing bolt which is not shown beyond the point of insertion and is secured to a connecting member 4 via threaded hole 41 and thereby transmits part of its weight to spring member 3. The static load transmitted in this way need not be considered for the present purpose; as far as the method of operation of the mounting according to the invention is concerned only the dynamic movements deriving from inward and outward oscillations are of importance.

The lower internal face of connecting member 4 is immersed in the damping fluid 6 and is externally decreasingly bevelled in the form of a truncated sphere at a comparatively small angle, and the internal surface of the head 71 of a set screw 7, which is inserted into a threaded hole 42 in the connecting piece opposite thereto, is formed in the spherical shape. The set screw 7 is used to attach a damping disc 8 to connecting member 4, for which purpose the part of the shaft of the screw directly connected to head 71 is provided with a shoulder-like cylindrical collar 72.

The damping disc 8, which is in the form of a virtually undeformable planar disc manufactured from metal or other rigid material, is provided with a central hole ddimensioned to correspond with, or be only slightly greater than, the external diameter of collar 72 so that it is introduced with a capacity for axial movement but with virtually no radial play between the spherical surfaces of parts 4 and 71 in the mounted condition illustrated in Fig. 1. As can be seen from the plan view in Fig. 1 a the central hole d is constructed somewhat in the manner of a four-leafed clover by the provision of four segmental gaps 81 angularly disposed about its periphery. The radial guidance of collar 72 is not however affected thereby.

Small in and out movements of the mounting are undamped because of the described axially movable arrangement of damping disc 8. The disc then remains uniformly at rest in the damping fluid and it only comes into contact with connecting member 4, or the head of set screw 7, when a given amplitude of vibration is exceeded. Contact between the two metal components 4 and 71 is under all circumstances strongly restrained as a result of the throttled flow of damping fluid through gaps 81 and the externally spherically decreasing contact surfaces and is therefore free of jarring or impact noise.

Claims

1. A hydraulically damped elastic mounting, particularly for the engine of a motor vehicle, includes a ring-shaped rubber spring member which seals a pot-shaped housing containing damping fluid and carries a damping disc immersed in a damping fluid on a rigid connecting member which passes centrally through the spring member forming a tight fit therewith, in which the damping disc, manufactured from a rigid material, is located movably in an axial direction on the connecting member between spherical or ballshaped buffer surfaces which arch back outwards and is provided with holes for the flow of damping fluid in the vicinity of the contact surface.

2. A mounting as claimed in claim 1, in which the damping disc is applied to the shaft of an axially movable interlocking set screw inserted into the connecting member.

3. A mounting as claimed in claim 1 or 2, in which the holes for the flow of fluid in the damping disc have the form of open gaps distributed at mutual angular spacings around the periphery of the central hole which accepts the shaft of the set screw.

4. A mounting as claimed in claim 2 or 3, in which the head of the set screw has a diameter substantially equal to that of the cylindrical connecting member and is of a spherical or ball shape on the surface opposite to the damping disc in the way as the frontal face of the connecting member.

5. A hydraulically damped electric mounting, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.