Patent ID: 6170381
Filing Date: 2001-01-09
Classification: B60T

Abstract:
A fluid power apparatus comprising a housing with a bore therein which is divided by a power piston into an inlet chamber and an outlet chamber, said power piston having passage means therethrough for connecting said inlet chamber with said outlet chamber, valve means for controlling the flow of a fluid under pressure from a source through said passage means, said valve means including a valve seal, a valve spring and an input rod, said valve spring urging said valve seal into engagement with said input rod to define a working chamber within said passage means, said fluid under pressure flowing from said inlet chamber to said outlet chamber by passing between said valve seal and a valve seat located in said working chamber, said flowing of fluid past said valve seat in a rest mode of operation developing a first turbulence which creates a non-resonant noise having an acceptable audible level of approximately 30 dB, said input rod responding to an actuation force from an operator by moving said valve seal toward said valve seat to restrict the flow of fluid from said working chamber and cause a corresponding fluid pressure change of the fluid in said inlet chamber, said corresponding fluid pressure change acting on said power piston to create an output force, said flowing of fluid from said working chamber to produce said output force creating a second turbulence which produces a resonance noise, said valve seal being characterized by a labyrinth ring having a cylindrical body with a first end and a second end, said first end having a face thereon with at least a first ring and a step which transitions into a conical surface connected to a base with a center opening, said face modifying said turbulence in fluid flowing from said inlet chamber and shifting the frequency of the fluid flowing past said valve seat such that said resonance noise of the fluid is below an acceptable audible range of 65 dB.