Valve assembly

Abstract

A valve assembly suitable for regulating the flow of fluid between a working chamber of a fluid-working machine and a fluid manifold. The valve assembly comprises a valve body comprising a valve seat, a fluid passage extending through the valve body, and a travelling member comprising a valve member, which valve member is operable between an open position in which the valve member is spaced apart from the valve seat and fluid can flow through the fluid passage and a closed position in which the valve member is in sealing contact with the valve seat preventing fluid from flowing through the fluid passage. The valve assembly defining a fluid flow path passing, in a first fluid flow mode, between the valve member and the valve seat, and into the fluid passage. The valve assembly is characterized by defining a fluid flow path including a constricted flow region and further comprising a reduced pressure chamber in communication with both a first surface of the travelling member and the constricted flow region, arranged to exert a force on the travelling member by way of a pressure reduction in the reduced pressure chamber when fluid is flowing along the fluid flow path, through the constricted flow region, which force acts to resist closure of the valve. Thus, a force is generated which opposes forces acting on the valve member due to the flow of fluid past the valve member.