Patent ID: 6113359
Filing Date: 2000-09-05
Classification: F04B

Abstract:
A hydraulic unit of the type including housing means, a shaft rotatably supported relative to said housing means, a cylinder block rotatably disposed within said housing means and associated with said shaft for rotation therewith; said cylinder block defining an output end and a plurality N of cylinders, and a piston member disposed for reciprocation within each of said cylinders, in response to rotation of said cylinder block; said housing means including an end cap disposed axially adjacent said output end of said cylinder bock and including a transverse interior surface and defining a first fluid kidney port opening into said interior surface, a high pressure port, and a first fluid passage providing open fluid communication between said first kidney port and said high pressure port, said first fluid passage being configured such that high pressure fluid in said first fluid passage is operable to deflect a portion of said end cap between said first fluid passage and said interior surface; a valve plate disposed intermediate said cylinder barrel and said end cap and fixed to be non-rotatable relative to said end cap, said valve plate including a valve surface in sliding engagement with said output end of said cylinder barrel, and an opposite surface in engagement with said interior surface of said end cap said valve plate further including port means configured to provide fluid communication of pressurized fluid between said cylinders and said first kidney port as said cylinder barrel rotates; characterized by:(a) said interior surface of said end cap and said opposite surface of said valve plate cooperating to define a relieved area;(b) said deflection of said portion of said end cap having a generally known transverse extent and a generally known axial extent; and(c) said relieved area being configured such that said known transverse and axial extent of said end cap deflection will not result in any substantial deformation of said valve plate in a direction toward said cylinder block.