Patent ID: 7431262

Claim:
In a proportional valve, the improvement comprising: a digital forcer having a plurality of solenoid actuators, each having a stationary member, a moveable member, at least one solenoid coil and a return spring, the stationary member and moveable member, when the moveable member is in a first position, defining a zero air gap magnetic circuit, the spring being disposed to urge the moveable member away from the first position, the moveable member moving to the first position in response to a latching current pulse in one of the solenoid coils of a first magnetic sense, and being retained in the first position after termination of the latching current pulse by residual magnetism until released by a releasing current pulse in one of the solenoid coils of a second magnetic sense opposite the first magnetic sense; a valve member; the plurality of solenoid actuators being disposed and configured so that the spring in each solenoid actuator will cause a respective force on the valve member when the respective moving member is released; the forces exertable on the valve member by each spring being a respective one of a relative force in a binary sequence of relative forces.