Rapid shutdown and ecology system

Abstract

A dual function rapid shutdown and ecology system for fuel delivery systems for engines, specially aircraft gas turbine engines, is disclosed. The dual function is accomplished in a single module operated by a single electromagnetic solenoid valve commanded by the engine electronic control unit. Upon actuation of the solenoid valve, a large spring loaded piston strokes to the extreme of its travel creating a cavity having a volume sufficient to accommodate all fuel leftover in the fuel manifold and distribution system at shutdown, thus preventing atmospheric pollution or engine damage upon subsequent operation. Simultaneous with actuation of the solenoid valve, fuel pressure differentials cause a small piston to stroke to the extreme of its travel opening fuel passageways and causing all the fuel being delivered to the engine combustion chamber to be bypassed back to pump inlet, thus effectively accomplishing the rapid shutdown function. An alternate embodiment allows for use of the dual function system on engines employing low pressure differentials along the various stages of the fuel control system manifold or where the ecology function is not required.

We claim:  
     
         1 . A gas turbine engine fuel control rapid shut down and ecology system comprising: 
 a cylindrically shaped valve body, internally bored to define a valve chamber having upper and lower ends;    a first cylindrical piston member placed internal to the valve chamber and movable therein along the longitudinal axis thereof;    a bored cavity at the upper end and along the longitudinal axis of the first cylindrical piston member;    a spirally wound spring positioned internal to the bored cavity at the upper end of the first cylindrical piston member, one end bearing on the base of the bored cavity and the other end bearing on the upper internal end of the valve chamber;    a bored cavity at the lower end and along the longitudinal axis of the first cylindrical piston member;    a second cylindrical piston member placed internal to the bored cavity at the lower end of the first cylindrical piston member and movable therein along the longitudinal axis thereof;    an annular shaped face plate attached to the lower end of the first cylindrical piston member to interlock the second cylindrical piston member within the bored cavity;    a fluid passageway connecting the upper end of the valve chamber to a gas turbine engine fuel manifold immediately upstream of combustion chamber atomizers;    a fluid passageway connecting a gas turbine engine fuel manifold immediately downstream of a high pressure fuel pump to the lower end of the valve chamber;    a fluid passageway, including an electrically actuated solenoid valve, connecting the lower end of the valve chamber to a gas turbine engine fuel manifold immediately downstream of a low pressure fuel pump;    a plurality of fluid passageways connecting the bored cavity along the upper end of the second cylindrical piston member to a gas turbine engine fuel manifold downstream of the low pressure fuel pump and upstream of a valve controlling the fuel pressure delivered to combustion chamber atomizers;    whereby when said gas turbine engine is turned off, said solenoid valve will simultaneously close causing fuel pressure differentials to drive both first and second cylindrical piston members downward thus rapidly terminating further fuel flow to the combustion chamber atomizers, and providing a temporary cavity to accommodate all fuel leftover in the manifold and distribution system at shutdown.    
     
     
         2 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 1 , wherein o-ring seals are provided at three circumferential locations of the valve chamber.  
     
     
         3 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 2 , wherein an o-ring seat is provided on the base of the bored cavity at the lower end of the first cylindrical piston member.  
     
     
         4 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 1 , wherein the diameter of the first cylindrical piston member is about 2.5 inches.  
     
     
         5 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 4 , wherein the stroke of the first cylindrical piston member within the valve chamber is about 1.5 inches.  
     
     
         6 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 1 , wherein a small orifice is provided on the fluid passageway connecting a gas turbine engine fuel manifold immediately downstream of a high pressure fuel pump to the lower end of the valve chamber.  
     
     
         7 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 1 , wherein the depth and diameter of the bored cavity at the upper end and along the longitudinal axis of the first cylindrical piston member is sized to provide a scavenge volume sufficient to accommodate all fuel leftover in the manifold and distribution system after shutdown.  
     
     
         8 . A gas turbine engine fuel control rapid shut down and ecology system comprising: 
 a first cylindrically shaped valve body, internally bored to define a valve chamber having upper and lower ends;    a first cylindrical piston member placed internal to the valve chamber and movable therein along the longitudinal axis thereof;    a bored cavity at the upper end and along the longitudinal axis of the first cylindrical piston member;    a bored cavity at the lower end and along the longitudinal axis of the first cylindrical piston member, said bored cavity having a diameter larger than the bored cavity on the opposite end of the first cylindrical piston member;    a spirally wound spring positioned internal to the bored cavity at the upper end of the first cylindrical piston member, one end bearing on the base of the bored cavity and the other end bearing on the upper internal end of the valve chamber;    a fuel passageway leading from an annular cavity along the outer surface of the first cylindrical piston member to a spring loaded accumulator valve;    a fuel passageway leading from the spring loaded accumulator valve to a witness drain;    a second cylindrically shaped valve body, internally bored to define a second valve chamber having upper and lower ends;    a second cylindrical piston member placed internal to the second valve chamber and movable therein along the longitudinal axis thereof;    a fluid passageway connecting the upper end of the first valve chamber to a gas turbine engine fuel manifold immediately upstream of combustion chamber atomizers;    a fluid passageway connecting a gas turbine engine fuel manifold immediately downstream of a high pressure fuel pump to the lower ends of both first and second valve chambers;    a fluid passageway, including an electrically actuated solenoid valve, connecting the lower end of the first valve chamber and upper end of the second valve chamber to a gas turbine engine fuel manifold immediately downstream of a low pressure fuel pump;    a fluid passageway connecting the upper end of the second valve chamber to a gas turbine engine fuel manifold upstream of a valve controlling the fuel pressure delivered to combustion chamber atomizers;    whereby when said gas turbine engine is turned off, said solenoid valve will simultaneously close causing fuel pressure differentials to drive both first and second cylindrical piston members downward thus rapidly terminating further fuel flow to the combustion chamber atomizers, and providing a temporary cavity to accommodate all fuel leftover in the manifold and distribution system at shutdown as well as all fuel contained in the annular cavity along the outer surface of the first cylindrical piston member.    
     
     
         9 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein o-ring seals are provided on the first cylindrical piston member at the upper transverse surface and at the bottom peripheral surface.  
     
     
         10 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein an o-ring seal is provided on the lower peripheral surface of the second cylindrical piston.  
     
     
         11 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein the diameter of the first cylindrical piston member at the lower end is about 2.5 inches.  
     
     
         12 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 11 , wherein the diameter of the of the first cylindrical piston member at the location of the o-ring seals on the upper transverse surface is about 2 inches.  
     
     
         13 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein the stroke of the first cylindrical piston member within the valve chamber is about 1.5 inches.  
     
     
         14 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein an orifice is provided on the fluid passageway connecting a gas turbine engine fuel manifold immediately downstream of a high pressure fuel pump to the lower end of the valve chamber.  
     
     
         15 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8 , wherein the depth and diameter of the bored cavity at the upper end and along the longitudinal axis of the first cylindrical piston member is sized to provide a scavenge volume sufficient to accommodate all fuel left over in the manifold and distribution system at shutdown.  
     
     
         16 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 8  wherein a fuel passageway leading from an annular cavity along the outer surface of the first cylindrical piston member is connected to a spring loaded check valve and thereafter to a fluid passageway downstream of the low pressure pump, thereby allowing for remote location of the first cylindrical piston member and valve chamber;  
     
     
         17 . A gas turbine engine fuel control rapid shut down and ecology system comprising: 
 a valve chamber containing a first spring loaded piston member movable along the longitudinal axis thereto and including a bored cavity for temporary storage of fuel;    a second piston member movable along the longitudinal axis thereto and placed internal to a bored cavity at the lower end and along the longitudinal axis of the first cylindrical piston member;    a plurality of fluid passageways connecting the valve chamber to a gas turbine engine fuel manifold at points downstream of the low pressure pump, high pressure pump, fuel pressure and flow control valves;    an electrically actuated solenoid valve placed on the fluid passageway from the valve chamber to a gas turbine engine fuel manifold immediately downstream of a low pressure fuel pump;    whereby when said gas turbine engine is turned off, said solenoid valve will simultaneously close causing fuel pressure differentials to drive both first and second cylindrical piston members downward thus rapidly terminating further fuel flow to the combustion chamber atomizers, and providing a temporary cavity to accommodate all fuel leftover in the manifold and distribution system at shutdown.    
     
     
         18 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 17 , wherein a separate second valve chamber is provided for housing the second piston member there within.  
     
     
         19 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 18 , wherein a fuel passageway leads from an annular cavity along the outer surface of the first piston member to a spring loaded accumulator valve.  
     
     
         20 . The gas turbine engine fuel control rapid shut down and ecology system of  claim 17 , whereby a fuel passageway leads from an annular cavity along the outer surface of the first cylindrical piston member to a spring loaded check valve and thereafter to a fuel control system manifold downstream of the low pressure pump thereby allowing for remote location of the first cylindrical piston member and valve chamber.  
     
     
         21 . A method of rapidly terminating fuel flow to gas turbine engine combustion chamber atomizers and providing a temporary storage volume to accommodate fuel left in the manifold after shutdown, said method comprising the steps of: 
 providing a fuel passageway from a gas turbine engine fuel manifold upstream of fuel chamber atomizers and leading to a valve chamber containing a first spring loaded piston member movable along the longitudinal axis thereto and including a bored cavity for temporary storage of fuel;    providing a plurality of fluid passageways from a gas turbine engine fuel manifold at points downstream of the low pressure pump, high pressure pump, fuel pressure and flow control valves, and leading to a second piston member movable along its longitudinal axis and placed internal to a bored cavity at the lower end and along the longitudinal axis of the first cylindrical piston member;    providing an electrically actuated solenoid valve placed on the fluid passageway from the valve chamber to a gas turbine engine fuel manifold immediately downstream of a low pressure fuel pump;    actuating said solenoid valve thereby causing fuel pressure differentials to drive both first and second cylindrical piston members downward thus rapidly terminating further fuel flow to the combustion chamber atomizers, and providing a temporary storage volume to accommodate all fuel left in the manifold after shutdown.    
     
     
         22 . The method of  claim 21 , wherein a separate second valve chamber is provided for housing the second piston member there within.  
     
     
         23 . A method of rapidly terminating fuel flow to gas turbine engine combustion chamber atomizers and providing a temporary storage volume to accommodate fuel left in the manifold after shutdown, said method comprising the steps of: 
 providing a scavenge volume of sufficient size to accommodate, for temporary storage, fuel remaining in a gas turbine engine fuel manifold upstream of fuel chamber atomizers after engine shutdown;    returning to a gas turbine engine fuel manifold, upon startup, said fuel that has been temporarily stored after engine shutdown;    terminating rapidly upon commanded shutdown any continued fuel flow to a gas turbine engine combustion chamber.