Rotary fluid pressure device and improved shuttle arrangement therefor

A rotary fluid pressure device of the type including housing means defining a first fluid port and a second fluid port;

• a rotary fluid displacement mechanism including an internally-toothed member and an externally-toothed member eccentrically disposed within said internally-toothed member for relative orbital and rotational movement therebetween;
• the teeth of said members 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 define a main fluid path operable to provide fluid communication between said first fluid port and said second fluid port through said fluid displacement mechanism;
• input-output shaft means and means operable to transmit torque between said externally-toothed member and said input-output shaft means;
• said valve means including a stationary valve member comprising a plate-like member disposed immediately adjacent said internally- and externally-toothed members and having a sealing surface disposed adjacent thereto;
• said stationary valve member having an axially opposite balancing surface disposed to be subject to fluid pressure in a pressure balancing chamber cooperatively defined by said housing means and said stationary valve member;
• shuttle valve means operable to communicate fluid pressure from said main fluid path to said pressure balancing chamber;
• characterized by:
• (a) said stationary valve member defining a shuttle bore disposed axially adjacent said pressure balancing chamber, and in open fluid communication therewith;
• (b) a shuttle valve member slidably disposed in said shuttle bore, and cooperating therewith to define first and second chambers disposed on axially opposite ends of said shuttle valve member;
• (c) said stationary valve member defining a lubrication passage communicating with said shuttle bore axially intermediate said first and second chambers;
• (d) first passage means providing fluid communication between said first fluid port and said first chamber, and second passage means providing fluid communication between said second fluid port and said second chamber;
• (e) said shuttle valve member being configured such that:
• (i) when said first fluid port contains high pressure, said shuttle valve member is biased to a first position, in which said shuttle valve member provides fluid communication between said first chamber and said pressure balancing chamber, and between said second passage means and said lubrication passage and
• (ii) when said second fluid port contains high pressure, said shuttle valve member is biased to a second position in which said shuttle valve member provides fluid communication between said second chamber and said pressure balancing chamber, and between said first passage means and said lubrication passage.