Patent ID: 7410349

Claim:
A pump assembly, comprising: a pump housing and a cover plate defining a pump cavity; a stator ring supported within said pump cavity in said pump housing; a pump ring rotatably supported within said pump cavity in said pump housing and which interfaces with said stator ring to define a plurality of variable volume pressure chambers; said cover plate covering said stator ring and said pump ring within said pump cavity, said cover plate being axially displaceable relative to said pump housing and defining a wall of each of said pressure chambers; and a biasing member that biases said cover plate toward said stator ring and said pump ring, wherein fluid pressure within said pressure chambers induces movement of said cover plate away from said stator ring and said pump ring, wherein said biasing member exerts a force having a magnitude allowing said stator ring and said pump ring to move based on the fluid pressure within said pressure chambers such that each translates to a position centered between said cover plate and said pump housing.