Two-piece balance plate for gerotor motor

A rotary fluid pressure device comprising housing means defining a fluid inlet port and a fluid outlet port;

• a fluid pressure displacement mechanism associated with said housing means and including an internally toothed ring member and an externally-toothed star member eccentrically disposed within said ring member;
• said ring member and said star member having relative orbital and rotational movement, and interengaging to define expanding and contracting fluid volume chambers in response to said orbital and rotational movement;
• valve means cooperating with said housing means to provide fluid communication between said fluid inlet port and said expanding volume chambers, and between said contracting volume chambers and said fluid outlet port;
• said housing means comprising an end cap assembly disposed rearwardly of said ring member and comprising part of said valve means, and a housing member disposed forwardly of said ring member;
• a plurality of fasteners disposed in fastener bores, said fasteners maintaining said end cap assembly and said housing member in tight sealing engagement relative to said ring member;
• and a balancing plate disposed between said ring member and said housing member and adapted to be closely disposed to an adjacent end surface of said star member, to minimize fluid leakage therebetween;
• said adjacent end surface of said star member defining a fluid chamber, and said star member defining a fluid passage communicating pressurized fluid from said main fluid flow path, upstream of said fluid displacement mechanism, to said fluid chamber to provide a fluid pressure bias of the star member toward said stationary valve member;
• characterized by:
• (a) said adjacent end surface of said star member comprising a plurality of individual star tooth surfaces;
• (b) each of said star tooth surfaces defining a generally radially extending fluid passage in communication with said fluid chamber;
• (c) each of said star tooth surfaces further including a fluid passage oriented generally perpendicular to said radial fluid passage, and having a decreasing flow volume in a direction away from said radial fluid passage, thus providing pressurized fluid between said balancing plate and said adjacent end surface of said star member.