Gas turbine engine fuel system with ecology valve

摘要

A gas turbine engine fuel system has an ecology valve for withdrawing residual fuel from primary and secondary fuel manifolds upon engine shut-down. The ecology valve has primary and secondary reservoirs respectively connected in fluid flow communication with the primary and secondary fuel manifolds. The valve further has a reciprocating piston movable from a retracted position when engine start-up is initiated to an extended position which the piston assumes under normal engine running conditions. The movement of the reciprocating piston between the retracted and extended positions controls the flow of fuel from and to the primary and secondary reservoirs. A cross-bleed passage is defined in the reciprocating piston. The cross-bleed passage connects the primary and secondary reservoirs in fluid flow communication only when the piston is in its extended position. In this way, the cross-bleed flow between the primary and secondary fuel manifolds may be initiated only at the end of the engine start-up phase.

主权项

1. An ecology valve for withdrawing residual fuel from a primary fuel manifold and a secondary fuel manifold of a gas turbine engine upon the gas turbine engine shut-down, the ecology valve comprising:
a variable volume primary reservoir having a primary port connectable in fluid flow communication with the primary fuel manifold; a variable volume secondary reservoir connectable in fluid flow communication with the secondary fuel manifold; a reciprocating piston movable within the variable volume primary reservoir and the variable volume secondary reservoir from a retracted position when engine start-up is initiated to an extended position which is assumed by the piston under normal engine running conditions, the movement of the reciprocating piston between the retracted position and the extended position reducing respective volumes of the variable volume primary reservoir and of the variable volume secondary reservoir, thereby flowing the fuel from the variable volume primary reservoir and the variable volume secondary reservoir to the primary fuel manifold and the secondary fuel manifold, respectively; and a cross-bleed passage defined in the reciprocating piston, the cross-bleed passage connecting the variable volume primary reservoir and the variable volume secondary reservoir in fluid flow communication only when the piston is in its extended position, the cross-bleed passage having an inlet and an outlet which are both in fluid flow communication with the variable volume primary reservoir when the reciprocating piston is in its retracted position.