Patent ID: 7484482

Claim:
A valve assembly suitable for use with an exhaust port of a two-stroke internal combustion engine, the valve assembly comprising: a valve actuator, the valve actuator including: a diaphragm; and a pressure chamber defined at least in part by the diaphragm, the pressure chamber being fluidly connectable to at least one pressure source, via a pressure control device, the pressure chamber having a volume variable in response at least in part to pressure supplied to the pressure chamber by the at least one pressure source; a valve operatively connected to the actuator, the valve being movable to a first position when a first pressure is supplied to the pressure chamber by the at least one pressure source, the valve being movable to a second position when a second pressure is supplied to the pressure chamber by the at least one pressure source, the valve being biased towards a third position, the valve being movable to the third position when a third pressure is supplied to the pressure chamber by the at least one pressure source, the third pressure being insufficient to overcome the bias, the third position being intermediate the first position and the second position; and a spring biasing the valve towards the third position.