Draftex Industries Limited

Pascal Tournier

An engine mount assembly comprises a rigid dome-shaped cover secured to the vehicle body or chassis. The cover supports internal rubber elements which in turn support rigid facing jaws. A damping module comprising two bellows chambers and an assembly of two valve elements is inserted in a unit, together with a valve arrangement. A bolt secured to the engine of the vehicle passes through the valve elements and holds the damping module in position and transmits engine vibrations to the damping module. Hydraulic fluid in the chambers is thus forced through a helical conduit which contains a restriction for damping the fluid movement and thus the vibrations. At higher vibration frequencies, valve flaps vibrate causing alternate small compression and expansion of the chambers and thus damping of the vibrations.

Vibration damping assemblies

An engine mount comprises a relatively stiff elastomeric member having an interior defining a first chamber containing hydraulic liquid. The elastomeric member is attached both to the engine and to the vehicle body. A flexible wall defines a second chamber and the two chambers are connected by a restricted channel. Engine vibration is transmitted to the liquid in the first chamber via the elastomeric member, and damping takes place because of the resistance to the flow of liquid between the two chambers or because of oscillation of the mass of the liquid in the restricted channel. In addition, a flexible membrane is supported by the interior wall of the elastomeric member and urged against this wall by a leaf spring, and the air pressure between the interior wall of the elastomeric member and the membrane is variable. When the air pressure is increased, the membrane moves away from the wall of the elastomeric member against the spring so that the first chamber is now partially defined by a flexible wall, thus reducing the damping effect and the stiffness.

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Orvault, France

Pascal Tournier