FR2461165A1 - SHOCK ABSORBING MOUNT - Google Patents

Abstract

A SHOCK-ABSORBING MOUNT (FOR EXAMPLE FOR SUPPORTING A VEHICLE ENGINE ON THE VEHICLE CHASSIS), INCLUDES A TUBULAR SUPPORT BODY 10 CONNECTED BY AN ELASTOMERIC ANNULAR ELEMENT 16 TO A COUPLING BODY 22. THE TUBULAR BODY 10 IS CLOSED BY A CROSS WALL 34 SO THAT A CHAMBER 40 IS DELIMITED INSIDE BETWEEN THE CROSSWALL 34 AND THE ANNULAR ELEMENT 16. THIS CHAMBER 40 IS FILLED WITH DAMPING LIQUID. A PLATE ELEMENT IN THE FORM OF A PISTON 32 DIVIDES CHAMBER 40 INTO TWO SUB-CHAMBERS 40A, 40B COMMUNICATING AROUND THE PERIPHERY OF THE PLATE ELEMENT 32. THE PLATE ELEMENT 32 IS CONNECTED BY A ROD 26 TO THE ORGAN COUPLING 22 SO THAT HIGH AMPLITUDE OSCILLATIONS OF THE LATTER CAUSE THE FLUID TO FORCE PASS BETWEEN THE SUB-CHAMBERS 40A, 40B TO PRODUCE A FLUID CUSHIONING EFFECT. AT LEAST A PART 34 OF THE WALLS OF THE CHAMBER MAY ELASTICALLY DECLINE TO ALLOW THE ABSORPTION OF LOW AMPLITUDE OSCILLATIONS WITHOUT PRODUCING A FLUID CUSHIONING EFFECT.

Description

246 1,165

The present invention relates to a shock-absorbing mount.

  shock structure intended to support an oscillating body on a support structure, and in particular but not exclusively mountings for supporting the engine of a motor vehicle on the chassis of the vehicle. Known shock absorption mounts of the type comprising a tubular support body designed to

be fixed on a support structure; a delivery body

fully disposed coaxially with said tubular support body

  laire and used to couple the mount to the oscillating body; an annular elastomer element fixed respectively by

its inner and outer peripheral parts to an extremi-

  tee of the tubular support body and the coupling member-

  is lying; and a fluid damper intended to dampen the oscillations of the coupling member with respect to

the tubular support member.

  Shock absorbing mounts of this type

  serve to dissipate part of the energy of the body

  lant and thereby determine sufficient absorption of the vibrations of this body which avoids oscillations of excessive amplitude which might otherwise occur, for example when the frequency of the vibrations of the oscillating body approaches the resonance frequency of the body. In some applications, it is desirable

  to have a significant damping effect when the

  lations of the oscillating body have a high amplitude, (that is

i.e. a low frequency), and an extremely low damping effect when the oscillations are of low amplitude (high frequency). In particular, the frame

supporting an engine on the chassis of a motor vehicle

bile must determine an effective damping of the

  lations of the engine when it is running at low speed or when the vehicle is subjected to sudden jolts produced by rough terrain, while when the engine is running at high speed, the damping determined by the mount must be as small as possible and sufficient so that the engine is isolated from the chassis and -2 -

comfortable walking conditions are ensured.

  An object of the present invention is to provide a

shock absorbing frame of the type mentioned above

  known and which while being very simple, robust and effective, is constituted in such a way that the fluid damper becomes effective only when the amplitude of the oscillations

  of the oscillating body exceeds a given value.

To achieve this goal, the present invention proposes

  a shock absorbing mount of the type specified above

  above and in which - the tubular support body is provided at its end remote from the annular elastomer element with a transverse wall which, with the annular element, delimits a chamber inside said support body

  tubular, this chamber containing a damping liquid

  mentally; - The coupling member is provided with a rod extending coaxially inside the chamber and carrying a transverse plate element which divides the

  room in two sub-rooms, these sub-rooms communicate

  as for each other via an annular passage comprised between the internal wall of the tubular support body and the periphery of said plate element, and - at least part of the walls of the internal chamber

yields elastically to absorb latent variations

- Volume in the chamber due to oscillations of the coupling member relative to the tubular support body whose amplitude is less than a predetermined value. A shock absorbing mount implementing the invention capable of being used for mounting a motor vehicle engine on the chassis of a

  vehicle will now be described in detail, by way of example

ple, with reference to the attached schematic drawings in which:

  Figure 1 is an axial section of the shock mount

shocking;

246 1,165

  Figure 2 is an axial section of a first variant of the frame of Figure 1; Figure 3 is a sectional view along III-III of Figure 2; Figure 4 is an axial sectional view of a second variant of the frame of Figure 1, and Figure 5 is a plan view in the direction of the arrow

V of Figure 4.

- As shown in Figure 1, the shock absorbing mount includes a tubular metal support body

intended to be fixed to the chassis of the motor vehicle

the. The tubular body 10 is provided at one end with an annular flange 12 and it coaxially supports at its opposite end a metal ring 14. The internal surface of the ring 14 is of frustoconical shape which diverges upwards. To the internal surface of the ring 14 is fixed a correspondingly shaped part of the external surface 18 of an annular element 16. The element 16 is made of elastomer and has the general shape of a bell with a

  central frustoconical opening and diverging upwards.

The upper part of the external surface 18 of the element 16 is of convex shape and the lower part of the internal surface 20 of the element 16 is of concave and convex shape. A metallic coupling member 22 constituted by a double-ended socket of frustoconical external shape is fixed in position inside the frustoconical central opening of the element 16, its widest part being at the top. The coupling member 22 is provided with two axial and threaded blind holes 24 and 30 which open respectively in the upper and lower end faces of the member 22. The upper axial hole 24 serves

  to the engagement of a corresponding threaded coupling member

  and not shown, which is fixed to the engine of the vehicle.

  In the lower axial hole 30 of the coupling member 22 is engaged the threaded end portion 28 of a rod 26 disposed coaxially inside the tubular support body - 4 - 10. The end of the rod 26 which is opposed to

  the threaded part 28 supports an element in a trans-

  versal in the form of a & washer 32.

At its end remote from the elastomer element 16, the tubular support member 10 is closed by a transverse wall 34 in the form of an annular diaphragm made of elastomeric material 36, the periphery of which is fixed to an annular flange M8. The collar 38 is connected

  to the annular collar 12 of the tubular support member

  slide 10. In section, the diaphragm 36 has a tooth profile

  saw due to a number of concentric annular grooves

triques 36a, 36b formed respectively on the surface

internal and on the external surface of the diaphragm 36.

The tubular support body 10 defines with the annular elastomer element 16 and the transverse wall 1 a

  chamber 40 containing a damping liquid. The rondel-

32 divides room 40 into a first room

variable volume 40a and a second chamber with variable volume

ble 40b communicating with each other by an annular passage 42 comprised between the internal wall of the body

  tubular support 10 and the peripheral rim of the round

cross section 32.

  In operation, the tubular support body 10 is fixed to the chassis of a motor vehicle and the coupling member 22 is connected to a part of the vehicle engine. While the engine is running and / or when the vehicle is in motion, the shock-absorbing mount is capable of absorbing both the oscillations of the engine directed along the axis of the tubular body 10 and the

  oscillations perpendicular to this axis. The mounting frame

  shock absorption has a strong damping action in the presence of large amplitude displacement oscillations of the engine (produced for example when the engine is running at low speed or when the vehicle is passing over rough terrain), and a very weak action of 'damping in the presence of small amplitude oscillations (produced by -5- example when the engine is running at high speed). In general, any elastic deformation of the annular elastomer element 16 tends to produce a variation in volume of the chamber 40, and when this variation is below a certain level, it is compensated by the elastic deformation of the diaphragm 36. When the diaphragm 6 is completely distended, it then acts as a rigid element and it follows that the further deformation of the elastomer element 16 causes the damping fluid to pass by force into the annular passage 42 between the chambers 40a and 40b to produce a damping effect

  viscous, the direction of this current depending on the deformation

mation of element 16 and depending on whether this deformation increases

  lie or decrease the volume of chamber 40a.

It will be understood that the small amplitude oscillations

  produce latent variations in volume in the cham-

  bre 40 which are completely absorbed by the elastic deformation of the diaphragm fi. As a result, there is no significant passage of fluid in the chambers 40a and 40b, and

that there is no viscous amortization.

  The variants of the shock absorbing mount which are illustrated in Figures 2 to 5 are generally similar to the embodiment shown in Figure

1, and in the rest of this description, we will only describe

  differences in detail, the same reference numbers being used to identify identical components

or the like.

In the first variant which is shown in Figures 2 and 3, the transverse wall 34 is constituted by a metal disc 44. The concave and convex internal surface 20 of the annular element 16 comprises a pair of depressions or depressions 46 arranged diametrically qpossIr; compared to each other. The annular element 16 therefore comprises

  two opposite surfaces 16a of reduced axial thickness giving

  providing element 16 with differential radial flexibility along two mutually perpendicular axes A and B

(see Figure 3).

In this variant, the transverse washer 32 is provided with an elastomeric pad 48 which faces the

disk li.

  In operation, the surfaces 16a of the element an-

  nular 16 are elastically deformed in the presence of small amplitude oscillations of the coupling member 22 relative to the tubular support body 10, so that the latent variations in volume of the chamber 40 are

absorbed without viscous damping thereby produced.

However, in the presence of large amplitude oscillations

  study, the surfaces 16a are quickly completely disten-

due and it follows that the annular element 16 acts, for the most part, as a rigid element. As a result, the damping fluid flows alternately

between the two chambers 40a and 40b passing through the passa-

annular age 42, which gives rise to a viscous type damping. Elastomer pad 48 acts as a stopper

  to limit the axial displacement of the coupling member

ment 22 towards disc 44.

  The second variant of the shock absorption mount shown in Figures 4 and 5 differs from the embodiment of Figure 1 only in that the convex external surface 18 of the annular element 16 is constituted by a pair of recesses or depressions 50 arranged diametrically opposite one another. The surface of the recesses 50 corresponds to that of a cylinder with a horizontal axis. Regarding the recesses 46 of the shock absorbing mount shown in the Figures

2 and 3, the recesses 50 provide the element 16 with flexibility

  differential radial unity along two mutual axes

  slightly perpendicular C and D (see Figure 5). In corres-

  pondance of the hollows 50, the element 16 comprises two surfaces

  16b whose axial thickness is reduced.

  When the second variant of the frame operates, the reduced thickness portion 16b deforms 6lastically,

  together with diaphragm 36, to absorb varia-

  latent volume in chamber 40 from -7-

  of low amplitude oscillations of the coupling member

  ment 22 relative to the tubular support body 10 and

  without production of viscous damping.

  The number and shape of the recesses 46 of the shock absorbing mount shown in Figures 2 and 3 and the recesses 50 of the shock absorbing mount shown in Figures 4 and 5 may be variable thus , for example, it is possible to provide more than two recesses spaced circumferentially from one another around the element 16, and the recesses can be present under

the shape of radially spaced concentric annular grooves

each other.

-8 -

Claims (9)

  1. - Shock absorbing mount intended to support, carry an oscillating body on a support structure, and in particular but not exclusively support frames   carrying the engine of a motor vehicle on the chassis of the vehicle, comprising a tubular support body adapted to be fixed on a support structure; a coupling member disposed coaxially with said tubular support body and serving to couple the mount to the body   oscillating; an annular elastomer element fixed, res-   pectively, by its internal peripheral parts - and ex-   dull, at one end of the tubular support body and   to the coupling member, and a fluid damper   designed to dampen the oscillations of the coupling member with respect to the tubular support member, characterized in that: - the tubular support body (1) is provided, at its   far end of the annular elastomer element (16)   re, a transverse wall (34, 44) which, with the annular element (16), delimits a chamber (40) inside said tubular support body (10), this chamber (40) containing a liquid depreciation; - the coupling member (22) is provided with a rod (26) extending coaxially inside the chamber (40) and carrying a transverse plate element (32) which divides the chamber (40) in two sub-chambers (40a, 40b), these sub-chambers (40a, 40b) communicating with each other via an annular passage (42)   between the inner wall of the tubular support body the surface (10) and the periphery of said plate element (32), and - at least a part of the walls of the internal chamber (40) yields elastically to absorb variations latent volume in the chamber (40) due to the oscil-   lations of the coupling member (22) relative to the tubular support body (10) of less amplitude   greater than a predetermined value. 2. - Shock absorbing frame according to the resale -9_ dication 1, characterized in that the transverse wall (34) of the tubular support body (10) is in the form of an elastic diaphragm (36) and constitutes said part of the chamber wall which may give way.   3. - shock absorbing frame according to claim 2, characterized in that the annular elastomer element (16) has surfaces of reduced axial thickness   (16b) forming other elastically deformed wall parts mables from said chamber (40). 4. - Shock absorbing mount according to the claim   cation 3, characterized in that said thick surfaces reduced axial force of the annular element are formed by depressions (50) spaced circumferentially on the external surface (18) of the annular element (i6). 5. - Shock absorbing frame according to the resale dication 4, characterized in that said depressions (50) are two in number and are arranged diametrically   opposite to each other.   6. - Shock absorbing frame according to the resale dication 1, characterized in that said transverse wall   (44) of the tubular support body (10) is rigid, the element   annular ment (16) being provided with surfaces of reduced axial thickness (16a) constituting said wall portion of the room (40) which can yield.   7. - Shock absorbing frame according to the resale   dication 6, characterized in that the surfaces of reduced axial thickness of the annular element (16) consist of depressions (46) circumferentially spaced and provided in the internal surface (20) of the annular element (î6).   8. - Shock absorbing frame according to the resale dication 7, characterized in that said depressions (46) are two in number and are arranged diametrically opposite to each other.   9 ._- Shock absorbing mount as claimed cation b, characterized in that the plate element trans-   versal (32) is provided with an elastomeric pad (48) made   sant facing the transverse wall (44) of the support body tubular (10).