Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2000-12-19
2002-04-16
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140140, C267S122000
Reexamination Certificate
active
06371462
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to active hydraulic anti-vibration supports and to active anti-vibration systems incorporating such supports. Such supports are specifically intended for mounting engines on the bodies of motor vehicles and are designed to produce counter-vibrations to cancel out the effects of the vibrations generated by these engines.
BACKGROUND OF THE INVENTION
More specifically, the invention relates to an active hydraulic anti-vibration support designed to be inserted between two rigid elements and comprising:
first and second rigid armatures intended to be fixed respectively to the two rigid elements to be connected,
an elastomer body linking the two armatures to one another and partially bounding a working chamber filled with liquid,
a flexible wall partially bounding a compensating chamber filled with liquid, which is connected to the working chamber by a throttled passage also filled with liquid,
an exciter member having a first face communicating with the liquid contained in the working chamber and a second opposing face isolated from said working chamber, said exciter member being mounted so that it can move in a direction of displacement substantially perpendicular to the first and second faces of the exciter member, starting from a non-operating position,
a control device designed to displace the exciter member at least in a first direction in said direction of displacement into an end stop position,
an elastic return device permanently applying a force to the exciter member to return it to its non-operating position, in accordance with a certain elasticity curve which imparts said return force depending on the displacement undergone by this exciter member parallel with the direction of displacement, this curve having a tangent for a first displacement value (zero or not) corresponding to the non-operating position of the exciter member, and the return force having a certain threshold value for a second displacement value corresponding to the end stop position of the exciter member.
In known anti-vibration supports of this type, the elastic return device is substantially linear so that the elasticity curve essentially corresponds to said tangent.
These anti-vibration supports are satisfactory in terms of their function but nevertheless have the disadvantage of requiring a particularly powerful control device to immobilize the exciter member in its end stop position, especially if the vehicle engine is operating at a relatively high speed.
In effect, this being the case, the control device must apply to the exciter member a force which is significantly greater than said threshold value of the return force in order to guarantee that the exciter member will remain immobilized in spite of the dynamic stress applied to this member.
As a result, the control device must be over-rated if it is to be capable of immobilizing the exciter member, which makes this control device relatively heavy and expensive.
OBJECTS AND SUMMARY OF THE INVENTION
The objective of this invention is to overcome this disadvantage in particular.
To this end, an anti-vibration support as proposed by the invention is characterized in that the elasticity curve of the elastic return device is non linear and is located below said tangent, at least in the vicinity of the second displacement value.
As a result of these features, the force which the control device needs to exert in order to immobilize the exciter member in its locked position is less than the force that would be needed in the known anti-vibration supports, which means that it is no longer necessary to provide a higher capacity control device.
Preferred embodiments of the anti-vibration device proposed by the invention may incorporate one and/or the other of the following features:
the elasticity curve of the return device has a maximum between the first and second displacement values;
the elasticity curve of the return device has a minimum substantially on a level with the second displacement value;
the elasticity curve of the return device has a linear initial part;
the exciter member has an elastomer membrane which at least partially forms the return device, this membrane being of a substantially truncated cone shape in the non-operating position, converging towards the working chamber from an annular base joined to a rigid partition bounding said working chamber;
the exciter member has a rigid central wall which is joined to the rigid partition by the elastomer membrane;
the elastomer membrane has an annular zone of a reduced thickness in the vicinity of its annular base;
the control device has a pneumatic chamber which is in contact with the second face of the exciter member and which is designed to be linked selectively either to a vacuum source or to the atmosphere.
Another objective of the invention is to provide an active anti-vibration system comprising:
at least one active hydraulic anti-vibration support as defined above, in which the control device consists of a pneumatic chamber in contact with the second face of the exciter member,
and an actuating device which is designed to be linked to at least one device serving as a sensor which receives information representative of the engine speed of the vehicle, this actuating device being designed to:
cyclically link the pneumatic chamber with a vacuum source and to the atmosphere to cause the exciter member to vibrate so as to generate counter-vibrations in the working chamber if the information received by the device serving as a sensor indicates that the vehicle engine is operating at an idling speed;
and link the pneumatic chamber permanently to the vacuum source if the information received by the device serving as a sensor indicates that the vehicle engine is operating at a speed higher than the idling speed so that the exciter member will then be retained in its end stop position.
Advantageously, the actuating device is designed so that the pneumatic chamber applies a mean force to the exciter member corresponding to a linear initial part of the elasticity curve of the return device if the engine is idling.
REFERENCES:
patent: 5167403 (1992-12-01), Muramatsu et al.
patent: 5170998 (1992-12-01), Muramatsu
patent: 5215293 (1993-06-01), Muramatsu et al.
patent: 5217211 (1993-06-01), Ide et al.
patent: 5314173 (1994-05-01), Ide et al.
patent: 3 801 108 (1989-07-01), None
patent: 196 20 219 (1996-11-01), None
patent: 2 301 165 (1996-11-01), None
French Preliminary Search Report dated Sep. 18, 2000, French Appl. No. FR 9916243.
Hutchinson
Marshall Gerstein & Borun
Oberleitner Robert J.
Sy Mariano
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