| 摘要 |
<p>A liquid-gas spring, such as for controlling the back rest of a vehicle seat, has a main piston (26) carrying a piston rod (18) and defining first and second liquid-filled chambers (30,31). First and second normally-open valves (34,84), and a control valve (74) which is operated externally by a control rod, (62) control the flow of liquid between the first and second chambers (30,31) via a passageway (42) in the main piston (26). When the control valve (74) is open, liquid transfer enables the position of the piston rod (18) to be adjusted. A second piston (96) is subjected to the pressure in the second chamber (31) through a third normally open valve (108) and defines a gas-filled chamber (100). The second piston (96) moves to accommodate changes in volume caused by the piston rod (18). In the event of a violent mechanical shock to the vehicle, the sudden increase in pressure in either liquid-filled chamber (30,31), depending on the direction of the shock, causes the first (34) or the second (84) valve to close so as to block liquid transfer and to lock the piston rod (18) even if the control valve (74) is open. A sudden such increase in pressure in the second chamber (31) also causes the third normally open valve (108) to close. <IMAGE></p> |
