Patent ID: 7114518

Claim:
A valve assembly comprising: a valve body defining a fluid passage extending through said valve body, said fluid passage having a first end and an opposite second end, said first end defining a first port through which fluid is communicated to and from said fluid passage and said second end defining a second port through which fluid is communicated to and from said fluid passage; a biasing element; a valve member moveably disposed within said fluid passage within said valve body, said valve member having a travel length extending from a first position relative to said valve body to a second position relative to said valve body, said biasing element biasing said valve member along said travel length from said first position toward a third position disposed between said first and second positions, said valve member at least partially defining a variable first opening, a second opening and at least one third opening, said first opening defining a variable constriction in said fluid passage between said first and second ends and having an area which progressively increases as said valve member moves from said first position toward said third position, said second opening and said at least one third opening defining said second port wherein when said valve member is disposed between said first position and said third position said second port is defined substantially solely by said second opening and when said valve member is in said second position said second port is defined by both said second opening and said at least one third opening; wherein said valve member defines a valve member passage extending from said second port to said first opening, said biasing element being disposed outside said valve member passage; and wherein fluid flow through said fluid passage within said valve body in a first direction from said second end toward said first end exerts pressure upon said valve member and biases said valve member toward said first position and wherein fluid flow through said fluid passage within said valve body in a second direction from said first end toward said second end exerts pressure upon said valve member and biases said valve member toward said second position.