Staged fuel injection system with shuttle valve and fuel injector therefor

摘要

A fuel injection system for a gas turbine engine combustion chamber comprises at least one pilot fuel injector (PI) having a fuel discharge passage communicated to the combustion chamber and at least one secondary fuel injector (S1) having a fuel discharge passage communicated to the combustion chamber and a fuel purging passage communicated to a higher pressure region upstream of the combustion chamber. A fuel flow control device supplies metered fuel flow to the pilot fuel injector under all regimes of engine operation and to the secondary fuel injector under certain, intermittent regimes of engine operation requiring fuel flow above a selected level. A shuttle valve (110) is movable to a first position to provide fuel flow communication between the fuel control device (SFDV) and the fuel discharge passage of the secondary fuel injector (S1) for fuel injection to the combustion chamber. The shuttle valve (110) also is movable to a second position to communicate the fuel discharge passage and the fuel purging passage of the secondary injector (S1) to the higher pressure region to purge fuel from the fuel discharge passage to the combustion chamber. The shuttle valve (110) is communicated at all times to pilot inlet fuel pressure and biased by a spring (120) in a manner to position the shuttle valve at the second purging position when fuel flow to the secondary injector is controlled below the selected level and is communicated to secondary fuel inlet pressure when fuel flow thereto exceeds the selected level such that the secondary fuel pressure on the shuttle valve overcomes the pilot fuel inlet pressure and the spring means to position the shuttle valve at the first injection position.