Patent ID: 8602381

Claim:
A valve assembly for regulating a supply of fluid from a high pressure manifold to a working chamber of a fluid working machine, the valve assembly comprising a primary valve, a secondary valve, an electromagnet and an armature, the primary valve comprising a face-seating primary valve member and a primary valve seat, the secondary valve comprising a secondary valve member moveable between a sealing position and an open position in which the secondary valve provides a path for fluid to flow between opposite sides of the primary valve member to reduce the pressure difference across the primary valve member, wherein the armature is coupled to the secondary valve member and slidable along a path extending between a first position and a second position, the second position being closer to the electromagnet than the first position, wherein, in the first position, the primary valve member is biased towards the primary valve seat and the secondary valve member is biased towards the sealing position, and in the second position, the primary valve member is biased away from the primary valve seat and the secondary valve member is biased towards the open position, wherein the coupling between the armature and the secondary valve member is configured to enable the armature to move from the first position towards the second position without a corresponding movement of the secondary valve member, but to exert a force through the coupling between the armature and the secondary valve member to cause the secondary valve member to move and to thereby open the secondary valve, while the armature is at a location between the first position and the second position along said path.