Abstract: An improved pneumatic control valve apparatus which uses poppet valves as the primary valve components. The poppets are in a pair of poppet valve assemblies, each assembly containing a pair of spaced poppets on a shiftable shaft biased in one direction to cause the poppets to close respective valve seats and to open the valve seats when the shaft moves in the opposite direction. A roller diaphragm is used to couple the shaft to an adjacent support of the assembly. As the shaft moves in the opposite direction against a bias force, the roller diaphragms of each assembly flex in a rolling action to coordinate the movements of the poppets and the shaft. The poppets will simutaneously open their respective valve seats so that the same amount of fluid will flow through the valve seats and thereby assure precision movements of the shiftable parts of the work-producing device with which the poppet valve assemblies are coupled.

Abstract: An electrically controlled valve using a piezoelectric strip as an actuator can be constructed so as to include a valve body having separate pressure and return chambers connected by two different load passages. These load passages are connected to service ports used to connect a load to the valve. These passages are open at their ends into the two chambers. A pressure port is used to supply a fluid under pressure to the pressure chamber while a return port is used to convey fluid from the return chamber. The actuator is mounted in such a manner that it can be actuated by an electric signal to move with respect to the openings in the chambers so as to cause an increase in the pressure in one of the load passages and a decrease in the pressure in the other. The position of the actuator can be reversed. When the valve is not in use the actuator is located so that the pressures in both of the load passages are the same.