Power plants – Reaction motor – Method of operation
Reexamination Certificate
1999-11-03
2002-02-05
Kim, Ted (Department: 3746)
Power plants
Reaction motor
Method of operation
C060S039094, C060S039010, C060S039830, C244S13500B
Reexamination Certificate
active
06343465
ABSTRACT:
BACKGROUND-STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH DEVEL.
Not Applicable
BACKGROUND-FIELD OF INVENTION
This invention relates to aircraft safety improvements, specifically an efficient, economical method of using an aircraft's propulsion or auxiliary Power engines, for new purposes of removing fuel tank fume-vapors and control of fuel tank temperature to reduce the potential of explosion and flammability there-in.
BACKGROUND-DESCRIPTION OF PRIOR ART
Past and present day engineering design in commercial and corporate-business a aircraft to remove explosion potential in fuel tanks has been to design out all energy sources which could ignite the explosive fumes there-in. The history of aircraft fuel tank explosions and especially the tragic results of the recent T.W.A. Flight 800 explosion and crash show that designing out all possible energy sources is impossible. Furthermore, even if it were possible to remove all on-board energy sources it would be impossible to remove external energy sources such as bullets, missiles, meteors and lightning strikes. Some solutions other than designing out energy sources have been proposed. One current proposal is to purge fuel tank ullage areas of dangerous explosive fume-vapors by ram air methods. Problems with ram air purge methods would be creation of aerodynamic drag penalties but more importantly they would deposit unburned hydrocarbons into the atmosphere. Another method proposes cooling the fuel tank ullage area to reduce flammability potential by introducing ram air past the fuel tank. Again, aerodynamic drag penalties occur with possible static electricity build-up problems of its own. A further problem with ram air purge methods is they can only operate when the aircraft is in motion and not at a standstill such as waiting on the tarmac for flight instructions. Another method proposal is to reduce the fuel tank ullage area and consequently the fume-vapor build-up by always carrying a minimum amount of fuel in the tank. Problems associated with this method are the continual weight penalties and operational constraints including the inability to always maintain the minimum amount of fuel in the tank. A final proposal to reduce fuel tank flammability is to cool fuel tanks by using colder fuel or fuel stored in underground tanks. Again, the main drawback is the operational constraint to maintain the fuel temperature after fueling.
Past and present day military solutions for the prevention of fuel tank explosions is to introduce inerting gases into the fuel tank ullage area so that dangerous fume-vapors will not accumulate there-in. The well known drawbacks to these systems are massive weight penalties and maintenance nightmares including the high cost and complexity of these systems. Historically the operation of these systems have created some safety problems of there own. Also, the displaced unburned hydrocarbons caused by these methods create atmospheric pollution. A current fuel tank inerting method proposes utilization of engine exhaust as an inerting gas. Problems associated with this method include the cost and weight of the system needed to treat and introduce exhaust gases to the fuel tank and the inherent corrosiveness of the exhaust products.
SUMMARY
In accordance with the broad aspects of the invention, an aircraft safety system includes an inexpensive, simple, efficient and effective method for purging and removing explosive and flammable fuel fumes and heat from the aircraft's a fuel tank and fuel tank compartment areas using the aircraft's operating dedicated propulsive or auxiliary power engines' low pressure suction intake action for a new use of purging aircraft fuel tank areas and as the driving method to remove fuel flames and heat to reduce explosive and flammability potential while replacing fumes and beat with outside ambient air mechanically refrigerated air or aircraft cabin-cockpit outflow air.
More specifically, ducting or conduit is provided, one end of which is in communication with the aircraft's fuel tank ullage area or fuel tank compartment, and the other end of the duct is coupled to the engine air intake area so that the operating engine's intake suction force is used to drive the system of purging and removing dangerous fumes and heat from the fuel tank areas and conducting them into the engine's combustion, chamber areas for combustion and exhaust. Additionally the removed fume and heat is replaced by ambient outside air, mechanically refrigerated air or cabin-cockpit overflow air through the tank or tank compartment intake valves.
In operation, this method of fume-heat removal method can be implemented by manual or automatic control servo-mechanism after the engine selected for this method is started and operating. The fumes and heat from fuel tank ullage or fuel tank compartment will exit the tank or tank compartment outflow-valve and be conducted via the duct or conduit from the higher pressure tank or tank compartment into the lower pressure engine's combustion area for combustion and exhaust to the atmosphere. Concurrently, outside air will enter into the tank or tank compartment inflow valve as the fume and, heat re-placement medium if the outside ambient air temperature is below a predetermined set temperature, if outside air temperature is above this preset temperature the replacement medium will be mechanically refrigerated air provided by the aircraft's mechanical equipment or cabin-cockpit conditioned outflow air. It should be obvious that while the aircraft is in flight or at altitude the majority of replacement air will be the outside ambient air however, while on the runway or tarmac waiting for take-off with a relatively high outside-temperature the replacement air may well be the aircraft's refrigerated air or cabin-cockpit outflow air.
Obvious advantages of this method of purging and removing dangerous fumes and heat by this method is that it is easy and inexpensive to implement as new manufacture or retrofit existing aircraft and due to it's simplicity, the system is highly reliable with relatively little added weight penalty and few maintenance problems. Furthermore, it is an added explosive deterrent against any errant energy source and can be used supplementary to any existing or future method or apparatus for this purpose as an added insurance. Additionally a major advantage of this method over proposed ram air methods for the same purposes is that this method can be used at a standstill while on the tarmac or runway and even while refueling the aircraft while ram air methods require forward motion to operate and when so doing, pollute the atmosphere with unburned hydrocarbons while this method combusts the unburned hydrocarbons before they are vented to the atmosphere. In this regard, the method has produced two unanticipated advantages which are, increased engine efficiency due to engine intake of unburned fumes and a decrease in the pollution of the atmosphere by unburned hydrocarbons due to their combustion before being vented to the atmosphere.
OBJECTS AND ADVANTAGES
Accordingly several objects and advantages of the present invention are:
(a) to provide the simplest and most efficient, economical, safest reliable method of removing aircraft fuel tank fume-vapors and maintaining tank temperature to reduce explosive amid flammability potential there-in;
(b) to provide a method to reduce an aircraft's fuel tank, explosive potential that can be easily and inexpensively retrofitted to existing aircraft systems;
(c) to increase the aircraft's- engine efficiency by enriching engine combustion intake air-with fuel fume-vapors;
(d) to combust unburned hydrocarbons that were previously vented to the atmosphere;
(e) to cool fuel tank ullage areas by drawing cooler ambient outside air into the fuel tank while removing fuel fume-vapors;
(f) to draw fume-vapors from the aircraft's fuel tank and replace them with mechanically temperature conditioned outside air;
(g) to draw fume-vapors from fuel tanks-connected
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