WO1989005245A1

WO1989005245A1 - A vehicle engine suspension device

Info

Publication number: WO1989005245A1
Application number: PCT/SE1988/000657
Authority: WO
Inventors: Göran SJÖSTRAND
Original assignee: Ab Volvo
Priority date: 1987-12-03
Filing date: 1988-12-01
Publication date: 1989-06-15
Also published as: JPH03503035A; SE459801B; US5035296A; DE3868282D1; SE8704847D0; EP0419478B1; EP0419478A1; SE8704847L

Abstract

A suspension arrangement for front-wheel drive vehicles equipped with transversely positioned engines. The suspension comprises a pair of compressible cushions (6, 7) which are arranged between the engine (3) and the engine bed (1), one of the cushions being located forwardly off the engine and the other rearwardly thereof. The cushions are inclined towards one another and have supports (17) which are intended to be fixated by and secured in complementary seats (20) located on the engine bed. When no load acts on the cushions, and the cushions are in their expanded state, the distance a between the cushions is greater than the distance b between the seats, but decreases to b under the influence of the weight of the engine.

Description

A vehicle engine suspension device

The present invention relates to a vehicle engine suspension device which comprises at least one pair of compressible engine cushions or pads connected to the engine and having supports intended for attachment to the seats of an engine bed plate, wherein the cushions are inclined towards one another in the direction of com¬ pression and the seats are inclined correspondingly.

It is conventional to position the engine cushions of each engine cushion pair located on respective opposite sides of a vehicle engine - as seen in its axial direction such that said cushions are inclined towards one another in the direction of compression and therewith cause the natural frequencies of the engine to lie within a narrower frequency band. In the case of known installations of this kind, the distance between the cushion supports in the absence of compressive load is equal to the distance between the seats on the chassis frame in the engine compartment. When the engine is lowered into the engine compartment and the supports come into contact with the seats, the cushions are subjected to shear forces as a result of the weight exerted thereon by the engine. Engine cushions, however, and particularly liquid-damped cush¬ ions, are primarily constructed to take up solely co - pression forces and their useful life will be shortened considerably if the cushions are subjected to excessive shear forces.

The object of the present invention is to provide a vehicle engine suspension system of the kind described in the introduction with which the engine cushions will be subjected solely to compression forces in the direction of symmetry. This object is achieved in accordance with the invention in that the distance between the supports in the expanded state of the cushions when no load acts thereon is so much greater than the distance between the seats as to ensure that essentially no shear forces will act on the cushions when the cushions are compressed under the weight of the engine.

Since the cushions are inclined towards one another, the lower ends of the cushions will move progressively closer together as the cushions are compressed.

By suitably adapting this mutual spacing in the absence of load to the degree of compressibility attainable and to the dead weight of the engine, it can be ensured that the compression resulting from the engine weight will be precisely that required to decrease the distance between the supports to an extent such that said distance will be equal to the distance between the seats when the cushions are subjected to the static weight of the engine. By

"engine weight" is meant here and in the following that part of the weight of the entire engine assembly, i.e. engine, clutch and gear box, which is to be supported by the cushions.

The invention will now be described in more detail with reference to exemplifying embodiments thereof illustrated in the accompanying drawings, in which Figure 1 is a perspective view of a complete engine suε- pension system intended for a transversely positioned engine.

Figure 2 is a side view of engine cushions and mounting, with the engine illustrated schematically, and Figure 3 is an enlarged view of the ringed area in Figure 2. The engine suspension illustrated in Figure 1 includes an intermediate frame 1 which is intended to be mounted on the vehicle chassis with the aid of resilient, vibration- -damping bushes 2, one at each corner of the frame. The frame 1 carries the engine 3, together with the gear box 4 and the vehicle steering transmission 5.

A pair of dampened engine cushions 6, 7 are mounted bet¬ ween the engine 3 and the frame 1, in front of and behind said engine respectively as seen in the direction of the vehicle long axis. The main function of the cushions is to dampen vertically acting engine movement and vibrations and will suitably be of the liquid-damped kind. The cush¬ ions are placed on respective sides of a plane extending vertically through the common centre of gravity of the engine and gear box. A third cushion 8 is mounted between the forwardly located edge surface of the engine and the right-hand side of the frame, the purpose of this third cushion being to impart a suitable natural frequency to the engine in the vehicle roll direction. This third cushion 8 may also be a liquid-damped cushion, although not necessarily so. A torque brace 9 is mounted reεilient- ly on the left-hand side of the engine block, above the gear box 4, one end of the brace being mounted on a torque arm 10 on the engine block and the other end thereof being mounted on a bracket 11 on the rear defining wall (not shown) of the engine compartment. A further torque brace 12 connects the engine with the intermediate frame 1. The main purpose of the braces is to counteract twisting of the engine when the vehicle is accelerated or braked.

The cushions 6, 7 also counteract tendencies of the engine to twist or likewise rotate. The cushions 6, 7 are best seen from Figures 2 and 3 and comprise a cylindrical, metal holder part 15, a resilient body 16 attached to the holder part and a metal, conical support element 17 which is attached to the resilient body 16 and has located therein a central, screwthreaded bore 18. Each of the holder parts 15 of the cushions 6. 7 is screwed firmly to its respective attachment 19 on the engine.. The attach- ments 19 each have a length dimension which is so adapted that a distance a_ between the cushion symmetry axes S' in the non-loaded state of said cushions is greater than a distance b_ between the symmetry axes S" of a pair of seats 20 on the frame 1. The differences are exaggerated in Figure 2, for the sake of illustration. The seats 20 have the form of a pair of conical recesses which are comple¬ mentary with the conical support elements 17 of the cushions .

Figure 2 illustrates the stage of an engine mounting process in which the outer side surfaces of the supports and the seats 20 are in contact With one another. As the engine is lowered, the resilient bodies 16 of the cushions 6, 7 are progressively further compressed until finally, when the whole weight of the engine rests on all three cushions 6, 7 and 8, they are compressed to an extent such that the symmetry axes S' and S" of the supports 17 and the seats 20 coincide, as illustrated in Figure 3. Thus as a result of this compression, the original distance a_ between the supports 17 is reduced to a distance b_, i.e. a distance which is equal to the distance between the seats 20.

The conicity of the cushion supports 17 and the seats 20 is effective in guiding the engine automatically into its correct position on the engine bed. When the engine is in place and the cushions 6, 7 compressed, as shown in Figure 3, a bolt (not shown) is screwed through the bottom of a respective seat and into a bore 18 in respective support elements 17. Although Figures 2 and 3 show the seats 20 and the supports 17 to have mutually the same conicity, the seats will preferably be slightly more pointed than the supports, so as to ensure a clearance- -free, or fully tight, connection when the securing bolts are tightened.

The distance a_ between the cushions 6. 7 is thus chosen with respect to the resistance of the cushions to com¬ pression and to that part of the engine weight which the cushions are intended to support such that the compression caused by the static load of the engine - in practice in the order of magnitude of 10 mm - will result in a re¬ duction in said distance a_. to the distance b_, and there¬ with ensuring that the resilient bodies of the cushions will not be subjected to shear forces.

Claims

1. A vehicle engine suspension arrangement comprising at least one pair of compressible engine cushions which are connected to the engine and which are provided with supports for attachment against seats located on an engine bed. the cushions being inclined towards one another in the direction of compression and the seats being corre¬ spondingly inclined, characterized in that the distance (a) between the supports (17) in the absence of load on the cushions (6_r 7) is so much greater than the distance (b) between the seats (20) that the cushion will be essen¬ tially free from shear forces when the cushions are com¬ pressed by the influence exerted by the weight of the engine.

2. An arrangement according to Claim 1, characterized in that the supports (17) and the seats (20) have at least substantially complementary conical surfaces with upwardly converging symmetry axes (S¹, S").

3. An arrangement according to Claim 1 or Claim 2, characterized in that the supports (17) have the form of inverse frustated cones, and in that the seats (20) are conical recesses.

4. An arrangement according to Claim 2, characterized in that the cone angle of the seats (20) is more acute than the cone angle of the supports (17).