Bush

Abstract

Various embodiments provide a bush for isolating vibrations, the bush comprising: a first anchor part defining a longitudinal axis; a second anchor part disposed coaxially with respect to the first anchor part; a first resilient body operably engaged with the first anchor part; a second resilient body operably engaged with the second anchor part; and an inertial mass element disposed between the first anchor part and the second anchor part, wherein the inertial mass element is independently connected to the first resilient body and the second resilient body, wherein the first resilient body, second resilient body and inertial mass element are arrange to isolate vibrations between the first anchor part and the second anchor part within a predetermined operational frequency range, and wherein the inertial mass element is arranged to isolate the first anchor part and second anchor part from dynamic stiffness increases associated with eigenmodes of the inner resilient body and the outer resilient body in the predetermined operational frequency range.

1 . A bush for isolating vibrations, the bush comprising:
 a first anchor part defining a longitudinal axis;   a second anchor part disposed coaxially with respect to the first anchor part;   a first resilient body operably engaged with the first anchor part;   a second resilient body operably engaged with the second anchor part; and   an inertial mass element disposed between the first anchor part and the second anchor part,   wherein the inertial mass element is independently connected to the first resilient body and the second resilient body,   wherein the first resilient body, second resilient body and inertial mass element are arranged to isolate vibrations between the first anchor part and the second anchor part within a predetermined operational frequency range,   wherein the inertial mass element is arranged to isolate the first anchor part and second anchor part from dynamic stiffness increases associated with eigenmodes of the first resilient body and the second resilient body in the predetermined operational frequency range, and   wherein the bush includes one or more snubber portions to physically limit an extent of relative radial movement between the first and second anchor parts, and wherein at least one of the first and second anchor parts includes the one or more snubber portions.   
     
     
         2 . A bush according to  claim 1 , wherein the inertial mass element occupies a non-resonant condition in the predetermined operational frequency range. 
     
     
         3 . A bush according to  claim 1 , wherein the inertial mass element occupies a resonant condition at a frequency below the predetermined operational frequency range. 
     
     
         4 . A bush according to  claim 1  having a dynamic stiffness characteristic that exhibits a single peak at a resonant frequency below the predetermined operational frequency range. 
     
     
         5 . A bush according to  claim 4 , wherein the resonant frequency is less than 1000 Hz. 
     
     
         6 . A bush according to  claim 1 , wherein one of the first and second resilient bodies includes axially extending passages therethrough to facilitate relative movement between the first and second anchor parts during loading. 
     
     
         7 . A bush according to  claim 6 , wherein both of the first and second resilient bodies include axially extending passages therethrough to facilitate relative movement between the first and second anchor parts during loading. 
     
     
         8 . A bush according to  claim 6 , wherein the axially extending passages include the one or more snubber portions which physically limit an extent of relative radial movement between the first and second anchor parts. 
     
     
         9 . A bush according to claim I, wherein the first anchor part is a rod extending along the longitudinal axis, and wherein the second anchor part is a sleeve surrounding the rod. 
     
     
         10 . A bush according to  claim 9 , wherein the inertial mass element is a rigid tubular body disposed coaxially with respect to the rod in between the rod and the sleeve. 
     
     
         11 . A bush according to  claim 10 , wherein the first resilient body extends radially between an outer surface of the rod and an inner surface of the rigid tubular body, and the second resilient body extends radially between an outer surface of the rigid tubular body and an inner surface of the sleeve. 
     
     
         12 . A bush according to  claim 10 , wherein the first resilient body is a solid resilient member that fills an annular volume between the rod and the rigid tubular body. 
     
     
         13 . A bush according to  claim 1 , wherein the first anchor part is a boss element and the second anchor part is a cup element arranged to receive the boss element therein, and wherein the first resilient body, second resilient body and inertial mass element together form a frustoconical interconnection between the boss element and the cup element. 
     
     
         14 . A bush according to  claim 13 , wherein the inertial mass element comprises a snubber portion for limiting relative axial movement between the boss element and the cup element. 
     
     
         15 . A bush according to  claim 14 , wherein the snubber portion comprises a radially extending plate. 
     
     
         16 . A bush according to  claim 14 , wherein the cup element comprises a top flange arranged to abut the snubber portion to restrict an axial distance by which the boss element is movable into the cup element. 
     
     
         17 . A bush according to  claim 1 , wherein the first anchor part is connectable to a first machine component and the second anchor part is connectable to a second machine component, whereby the bush is operable to isolate vibrations between the first machine component and second machine component. 
     
     
         18 . A bush according to  claim 17 , wherein the first machine component and second machine component are the engine and chassis of a vehicle.