Fluid working machine with valve actuator and method for controlling the same

Abstract

A fluid working machine has at least one working chamber of cyclically varying volume and low and high pressure valves to regulate the flow of working fluid into and out of the working chamber, from low and high pressure manifolds. The low and high pressure valves are actuated by electronically controlled valve actuation means which, when actuated, applies forces to the low and high pressure valve members to open and/or close the respective valves. The low and high pressure valve members are independently moveable and, although the low pressure valve member typically begins to move quickly in response to a shared valve control signal, the high pressure valve member typically moves only after a change in the pressure within the working chamber. The electronically controlled valve actuation means may be a shared electronically controlled valve actuator, such as a solenoid within a magnetic circuit which directs magnetic flux through both low pressure and high pressure valve armatures which are connected to the respective valve members.