Aeronautics and astronautics – Aircraft structure – Ice prevention
Reexamination Certificate
1999-09-09
2001-04-03
Eldred, J. Woodrow (Department: 3644)
Aeronautics and astronautics
Aircraft structure
Ice prevention
C244S13400A
Reexamination Certificate
active
06209823
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to the field of aircraft deicing, and more particularly, the present invention relates to an apparatus and method for deicing aircraft using forced air from a compressor unit.
BACKGROUND OF THE INVENTION
Some deicing systems and methods used for deicing snow and ice-covered aircraft surfaces use an apparatus that sprays large quantities of deicing fluids onto the aircraft surfaces. Typically, this has been accomplished by spraying a heated antifreeze fluid (e.g., a glycol and water mixture) onto the iced surfaces of the aircraft, together with a large quantity of compressed air. An example includes the system disclosed in U.S. Pat. No. 5,244,168, the disclosure which is hereby incorporated by reference in its entirety, where a nozzle mixes pressurized air and deicing fluid to provide a spray pattern for application to the aircraft to deice the aircraft.
Other systems separate the glycol and water mixture from the compressed air and include a separate nozzle for discharging compressed air by providing a forced air deicing system having a powerful compressed air source. Typically, these systems include a vehicle frame, such as the chassis of a truck, having a boom with one end mounted on the vehicle frame and a free end. An operator cab is positioned at the free end of the boom and a deicer air jet nozzle is connected at the free end of the boom, typically mounted on the operator cab for operator control.
Many of these systems use very powerful jet engine air start units. The air exits the nozzle at a temperature of 300° F. to 400° F. above ambient. As a result, some of the ice and snow is melted and can migrate into crevices on the aircraft. The aircraft acts as a heat sink because the large mass of the aircraft remains at subfreezing temperatures. Thus, sensitive sensors and critical trailing edge flaps may become frozen and ineffective.
Typically, this type of compressor is capable of 300 to 500 horsepower and provide 300 to 400 pounds a minute of compressed air. The units are very inefficient producing unnecessary hot air and excessive noise. Additionally, these systems are very heavy and must be positioned near the vehicle frame, a long distance from the operator cab carrying an air jet nozzle. As a result, long tubes must extend from the vehicle frame along the boom to the operator cab where the nozzles are located. These long runs from the compressor can cause thermodynamic and pneumatic deficiencies.
Also, any system that injects fluid at high pressure into the air stream has a drawback because the fluid could act as a cutting medium and damage aircraft surfaces. Therefore, it is essential in some instances to keep a great distance from the aircraft to avoid damaging the aircraft with the high pressure fluid, thus making the forced air system ineffective.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a n apparatus and method for deicing aircraft where a compressor unit, including any motor driving the compressor, can be mounted on the boom, proximate to a deicer air jet nozzle.
It is still another object of the present invention to provide an apparatus and method for deicing aircraft that uses forced air discharge that is efficient and uses a compressor unit that is lightweight, but generates an air discharge from a deicer air jet nozzle that is appropriate for deicing aircraft under frigid conditions, but also does not discharge at temperatures substantially above ambient temperature.
In accordance with the present invention, an apparatus and method for deicing aircraft now allows a compressor unit to be mounted on the vehicle boom by the use of a centrifugal compressor, such as the type of compressor commonly used when supercharging internal combustion engines. This type of compressor is directly connected to a motor output, which in a preferred aspect of the invention is a hydraulic motor via a transmission, such as a belt, and in a preferred aspect, a drive gear unit. The centrifugal compressor includes an impeller and outlet as is normal with many of the superchargers used in automobile vehicle engines. The apparatus includes a vehicle frame and a boom having one end mounted on the vehicle frame and a free end. The compressor unit is mounted on the boom proximate to the free end and a deicer air jet nozzle is connected at the free end of the boom and operatively coupled to the air outlet of the centrifugal compressor for receiving air and discharging the air for a deicer application.
A hydraulic pump is mounted on the vehicle frame and hydraulic feed lines extend from the hydraulic pump along the boom to the hydraulic motor for supplying hydraulic fluid under pressure to the hydraulic motor. The vehicle frame can typically include a vehicle engine, such as normal with a truck. A transmission is driven from the vehicle engine and interconnects the hydraulic pump for supplying power to the hydraulic motor.
A drive gear unit is operatively connected between the centrifugal compressor and the hydraulic motor for stepping up the revolutions per minute of the centrifugal compressor relative to the output of the hydraulic motor. The drive gear unit further comprises an input spur gear driven from the hydraulic motor and an output spur gear driving the centrifugal compressor. The input spur gear and output spur gear define about a 2:1 to about 4:1 gear ratio. The deicer air jet nozzle defines an axisymmetric contour having a converging portion. An example of such an air jet nozzle is disclosed in U.S. Pat. No. 5,755,404, the disclosure which is hereby incorporated by reference in its entirety.
Typically, a fluid nozzle is mounted on the deicer air jet nozzle. A source of deicing fluid could be mounted at the vehicle frame and a supply tube interconnects the source of deicing fluid in the fluid nozzle. A pump is operatively connected to the source and supply tube and pumps deicing fluid from the source of deicing fluid through the supply tube and fluid nozzle. Typically, if an aircraft contains much ice, the deicing fluid would be placed on the ice to aid in melting the ice. A centrifugal pump can typically inject deicing fluid into the air stream at 100 to 200 PSIG. Any greater pressure could create problems with aircraft damage.
A method aspect is also disclosed and includes the steps of compressing air within a centrifugal compressor located on a vehicle boom by driving a motor coupled to the centrifugal compressor and discharging the air from a deicer air jet nozzle attached to the end of the vehicle boom such that air is forced outward from the deicer air jet nozzle at about 100 pounds per minute.
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Allen Dyer Doppelt Milbrath & Gilchrist, P.A.
Eldred J. Woodrow
FMC Corporation
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