| 摘要 |
A vacuum control valve, which is particularly suitable for controlling an exhaust-gas-recirculation valve (15) in a diesel engine (11), is secured to the injection pump (10) of such engine and is actuated by the engine's setting shaft (23). It has a bell-shaped housing (30) and a double-seat valve (33, 44, 43) which is adjusted by way of a pair of cam rings (50, 60). One of the cam rings (50) is fixed in the housing and clamps the outer edge (42) of a flexible diaphragm (41), whose middle part is in the form of a closing element (43) and which carries a piston (45) having a valve closing element (44). The other cam ring (60) is rotatably and axially displaceably guided within the fixed cam ring and acts on the piston (45). The cam of the cam rings (50, 60) are either symmetrical or asymmetrical and their flanks have a uniform slope. Rotation of the shaft (23) and the cam ring (60) in a first direction lowers the piston (45) and with it the closing element (43), thus connecting valve (15) to a vacuum pump (22) when the vacuum above the piston (45) reaches a predetermined level, the piston will rise against the action of a spring (53) to isolate the pump (22). Rotation of the cam (60) in the opposite direction lifts the piston (45), from the closing element (43) which is held against the seat (33), thus bending the chamber (38) above the piston (45). <IMAGE> |
