Turbine engine compressor discharge pressure modulated transmission

Abstract

A gas turbine engine and automatic transmission power train having a modulator valve controlled by an engine compressor pressure and altitude responsive force actuator and a speed governor to provide a modulator pressure increasing with increasing engine power during normal engine operation and decreasing with increasing output speed operative to increase friction drive capacity and increase upshift speed with increasing modulator pressure. The force actuator provides a force which increases with increasing compressor discharge pressure and an altitude aneroid provides an opposing force decreasing with increasing altitude so the net actuator apply force increases with increasing compressor discharge pressure and altitude and is the same at the same engine power at all altitudes. The actuator has a compressor discharge pressure chamber having on one side a small apply diaphragm connected to a force apply member and on the other side a large release diaphragm and an apply spring acting through the diaphragms on the force apply member. When the engine is operating, minimum to maximum normal operating range compressor discharge pressure acts on the release diaphragm to disable the apply spring and on the apply diaphragm to provide with aneroid altitude correction an apply force increasing from a low value to a high value as compressor discharge pressure increases from minimum to maximum. On engine shut down or other loss of compressor discharge pressure when the engine is operating, as compressor discharge pressure decreases below the minimum operating value the release diaphragm release force is reduced and when compressor discharge pressure equals atmospheric pressure the apply spring force transmitted to the apply member provides a high modulator pressure operative in the transmission to delay upshifts to indicate this condition and to meet maximum drive torque requirements.