Patent ID: 9242627
Filing Date: 2016-01-26
CPC Classification: B60T,F16K,Y10T

Claim Text:
1. A valve assembly having a housing into which are provided a first port, a second port and a third port, and in which are located a first movable member, a second movable member and a third movable member, the first movable member being movable between a first position which causes the second movable member to close the first port to prevent any substantial flow of fluid through the first port, whilst the second and third ports remain open and flow of fluid between the second and third ports is permitted, a second position which causes the third movable member to close the third port to prevent any substantial flow of fluid through the third port, whilst the first and second ports remain open and flow of fluid between the first and second port is permitted, and a third position which causes the second movable member to close the first port and the third movable member to close the third port to prevent any substantial flow of fluid through either the first port or the third port, wherein the second movable member and the third movable member are separate such that relative movement between the second movable member and the third movable member is permitted; wherein there is a valve formation which surrounds the third port, which is fixed relative to the housing and which is configured such that engagement of the valve formation with a valve seat provided by the third movable member substantially closes the third port; wherein the third movable member is provided with a body which engages with a bearing surface of the housing, there being a seal which provides a substantially fluid tight seal between the bearing surface and the body of the third movable member whilst permitting movement of the third movable member relative to the housing; and wherein, when the valve formation engages with the valve seat so that the third moveable member substantially closes the third port, the area enclosed by the points of contact of the valve formation with the valve seat is greater than the area enclosed by the points of contact of the seal with the bearing surface, whereby the fluid pressure from the second port acts upon the third moveable member, thereby retaining the third moveable member in the closed position.