Patent ID: 6122905
Filing Date: 2000-09-26
Classification: F01D,F04D

Abstract:
In a gas turbine engine including a compressor with an axial fluid flow path, a bypass fluid flow path concentric with the compressor fluid flow path, a bleed valve in fluid communication with the compressor fluid flow path and the bypass fluid flow path whereby the bleed valve comprises a piston extending radially, with a piston head radially remote from the compressor fluid flow path, a pneumatic chamber surrounding a portion of the piston head and means for introducing compressed fluid into said chamber, the piston including a valving means and a rigid member extending between the piston head and the valving means whereby the piston is effective to open or close the communication between the compressor fluid flow path and the bypass fluid flow path, the improvement including a precompressed spring, precompressed to between 20 and 50 lbs., associated with the piston to normally urge the piston radially outwardly relative to the compressor fluid flow whereby the pneumatic pressure in the chamber surrounding the piston head must overcome the precompressed spring in order to close said valving means whereby the precompressed spring controls the closing schedule of the bleed valve to avoid the surge conditions of the engine.