Power plants – Combustion products used as motive fluid – Combined with starting feature
Reexamination Certificate
2001-12-11
2002-11-26
Casaregola, Louis J. (Department: 3746)
Power plants
Combustion products used as motive fluid
Combined with starting feature
C060S739000
Reexamination Certificate
active
06484510
ABSTRACT:
The present invention relates generally to fuel delivery systems for engines, especially aircraft gas turbine engines, and more particularly to ecology and fuel flow splitting functions for such fuel delivery systems.
Some fuel delivery systems for gas turbine engines require multiple fuel manifolds to segregate various types of fuel nozzles for optimal engine performance. A means of dividing this flow between the manifolds is therefor required. U.S. Pat. No. 5,809,771 Wernberg discloses an ecology valve and a fuel flow splitting valve having a single piston operable in two different regions, one for modulating flow to primary and secondary engine nozzles as a function of fuel pressure and another where flow to primary and secondary engine nozzles is determined by the fixed port geometry. It is very difficult to extend this concept to more than two distinct engine manifolds.
Some engines also require an ecology function that removes a set quantity of fuel from the engine fuel manifold(s) upon cessation of engine operation. Fuel removal is required for two reasons. First, it keeps fuel from vaporizing into the atmosphere. Second, it keeps fuel from coking on the engine's fuel nozzles, a condition that hinders nozzle performance. Prior art ecology systems have used an arrangement of pistons, check valves, plumbing, reservoirs and pumps to accomplish this task. In engines requiring multiple fuel manifolds, multiple ecology valves or a multiple chambered ecology valve have been used. These types of architecture result in complex, high cost and weight ecology systems. A two chambered valve is disclosed in the above-mentioned Wernberg U.S. Pat. No. 5,809,771. In the Wernberg system, fuel is simultaneously withdrawn from the two manifolds and a separate chamber is required for each engine manifold to ensure discrete fuel removal from those manifolds upon engine shut-down. It is also very difficult to extend this concept to more than two distinct engine manifolds. The Wernberg system employs at least one check valve downstream of the ecology valve for diverting a part of the modulated flow from the primary to the secondary manifold. Such downstream valving allows a degree of undesirable cross-talk between the manifold supply lines and may reduce engine fuel flow reliability or increase the load on the fuel supply pump. It is desirable to minimize the fuel remaining in an engine fuel manifold upon cessation of engine operation and to provide a compact, economical ecology function for fuel supply systems. It is also desirable to achieve such an ecology function by employing a simple single diameter piston valve which is controlled solely by a signal from a pressurizing valve, and to accomplish the ecology function while avoiding any cross-talk between the several manifold fuel supply lines thereby maintaining the fuel pressure integrity in those several lines. It is further desirable to avoid this cross-talk while achieving a fuel splitting function which is operable to appropriately distribute fuel to a plurality of engine fuel manifolds.
The present invention provides solutions to the above problems in the form of a fuel divider and ecology system adapted for an engine requiring three discrete fuel manifolds. One manifold contains atomizer nozzles (for engine start), and two manifolds contain air blast nozzles, one servicing the lower half and the other servicing the upper half of the engine. For the flow dividing function, the system incorporates a plurality of valves to appropriately distribute metered burn flow to these three fuel manifolds. This system accomplishes the ecology function using one single chamber staged valve, and modifying the main fuel control pressurizing valve to include a pressure switching function. This approach limits the ecology components to one ecology valve piston, and one plumbed line from the pressurizing valve to control it. The fuel splitting function is achieved by a first splitter valve which divides the fuel flow from a pressurizing valve between atomizer or start-up nozzles and air blast or main running nozzles; and a second splitter valve which subdivides flow between the upper and lower manifolds.
FUEL DIVIDER AND ECOLOGY SYSTEM FOR A GAS TURBINE ENGINE
The present invention relates generally to fuel delivery systems for engines, especially aircraft gas turbine engines, and more particularly to ecology and fuel flow splitting functions for such fuel delivery systems.
Some fuel delivery systems for gas turbine engines require multiple fuel manifolds to segregate various types of fuel nozzles for optimal engine performance. A means of dividing this flow between the manifolds is therefor required. U.S. Pat. No. 5,809,771 Wernberg discloses an ecology valve and a fuel flow splitting valve having a single piston operable in two different regions, one for modulating flow to primary and secondary engine nozzles as a function of fuel pressure and another where flow to primary and secondary engine nozzles is determined by the fixed port geometry. It is very difficult to extend this concept to more than two distinct engine manifolds.
Some engines also require an ecology function that removes a set quantity of fuel from the engine fuel manifold(s) upon cessation of engine operation. Fuel removal is required for two reasons. First, it keeps fuel from vaporizing into the atmosphere. Second, it keeps fuel from coking on the engine's fuel nozzles, a condition that hinders nozzle performance. Prior art ecology systems have used an arrangement of pistons, check valves, plumbing, reservoirs and pumps to accomplish this task. In engines requiring multiple fuel manifolds, multiple ecology valves or a multiple chambered ecology valve have been used. These types of architecture result in complex, high cost and weight ecology systems. A two chambered valve is disclosed in the above-mentioned Wernberg U.S. Pat. No. 5,809,771. In the Wernberg system, fuel is simultaneously withdrawn from the two manifolds and a separate chamber is required for each engine manifold to ensure discrete fuel removal from those manifolds upon engine shut-down. It is also very difficult to extend this concept to more than two distinct engine manifolds. The Wernberg system employs at least one check valve downstream of the ecology valve for diverting a part of the modulated flow from the primary to the secondary manifold. Such downstream valving allows a degree of undesirable cross-talk between the manifold supply lines and may reduce engine fuel flow reliability or increase the load on the fuel supply pump.
It is desirable to minimize the fuel remaining in an engine fuel manifold upon cessation of engine operation and to provide a compact, economical ecology function for fuel supply systems. It is also desirable to achieve such an ecology function by employing a simple single diameter piston valve which is controlled solely by a signal from a pressurizing valve, and to accomplish the ecology function while avoiding any cross-talk between the several manifold fuel supply lines thereby maintaining the fuel pressure integrity in those several lines. It is further desirable to avoid this cross-talk while achieving a fuel splitting function which is operable to appropriately distribute fuel to a plurality of engine fuel manifolds.
The present invention provides solutions to the above problems in the form of a fuel divider and ecology system adapted for an engine requiring three discrete fuel manifolds. One manifold contains atomizer nozzles (for engine start), and two manifolds contain air blast nozzles, one servicing the lower half and the other servicing the upper half of the engine. For the flow dividing function, the system incorporates a plurality of valves to appropriately distribute metered burn flow to these three fuel manifolds. This system accomplishes the ecology function using one single chamber staged valve, and modifying the main fuel control pressurizing valve to include a pressure switching function. This approach limits the ecology components to one ecology valve piston
Fisher Steven F.
Futa, Jr. Paul W.
Sharp Kevin R.
Allied-Signal Inc.
Casaregola Louis J.
Palguta Larry J.
LandOfFree
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