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Software logic for operating APU in Electric Taxi System for Aircrafts

IP.com Disclosure Number: IPCOM000239048D
Publication Date: 2014-Oct-06
Document File: 5 page(s) / 275K

Publishing Venue

The IP.com Prior Art Database

Related People

Lee Glascoe: INVENTOR [+2]

Abstract

The EGTS aircraft taxiing system (EGTS) employs light weight electric motors mounted on the Main Landing Gear (MLG) of the aircraft to taxi the aircraft prior to takeoff and after landing. The Auxiliary Power Unit (APU) supplies electric power to the motors and additionally supplies compressed air to drive pneumatic systems such as the Environmental Control System (ECS) and the Air Turbine Starter (ATS) used for Main Engine Starting (MES). Both the EGTS and the ECS, along with the normal aircraft electrical operating demands, are dependent on the APU when the aircraft main engines are not operating. During momentary peak electric power demands from the EGTS, the APU could encounter operating limits which will result in a reduction of electric power to the aircraft / EGTS or reduced pneumatic energy to the ECS or ATS. The present invention provides a solution for operating the APU during these momentary peak demand periods.

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Software logic for operating APU in Electric Taxi System for Aircrafts

Allan Steves and Lee Glascoe ABSTRACT

The EGTS aircraft taxiing system (EGTS) employs light weight electric motors mounted on the Main Landing Gear (MLG) of the aircraft to taxi the aircraft prior to takeoff and after landing. The Auxiliary Power Unit (APU) supplies electric power to the motors and additionally supplies compressed air to drive pneumatic systems such as the Environmental Control System (ECS) and the Air Turbine Starter (ATS) used for Main Engine Starting (MES). Both the EGTS and the ECS, along with the normal aircraft electrical operating demands, are dependent on the APU when the aircraft main engines are not operating. During momentary peak electric power demands from the EGTS, the APU could encounter operating limits which will result in a reduction of electric power to the aircraft / EGTS or reduced pneumatic energy to the ECS or ATS. The present invention provides a solution for operating the APU during these momentary peak demand periods.


1. Introduction

An aircraft burns significant quantities of fuel while taxiing about airports during landing or takeoff. The motive force for taxiing is conventionally provided by main propulsion engines which are inefficient during idle and at lower power settings, leading to burning significant quantities of fuel during taxi operation. For aircraft that execute short segment flights with frequent landings and takeoffs, up to 5-10% of the overall mission fuel can be burned on the ground. Some downsides in using the conventional main propulsion engines for taxiing are:


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- Fuel burnt in aircraft main propulsion engines during taxiing on runways of airports results in increased levels of exhaust and impacts the air quality at and around airports.

- Aircraft have to carry additional fuel (cost) to account for the fuel usage during taxiing.

The EGTS employs light weight electric motors mounted on the Main Landing Gear (MLG) of the aircraft to taxi the aircraft prior to takeoff and after landing. Power to the EGTS is provided by the aircraft's Auxiliary Power Unit (APU), as it uses significantly less fuel than the main propulsion engines of the aircraft. Aircraft control during EGTS operation is easier and more precise than that achieved using jet thrust. In addition to the savings in fuel burn, less operating time of the main propulsion engines on the ground means less chance for Foreign Object Damage (FOD) to be ingested into the engine intake which can cause damage to the engines. EGTS also allows the aircraft to operate in reverse on its own without the aid of a motorized tug.

A commercial aircraft APU serves two primary functions.
(1) Producing compressed air to drive aircraft pneumatic systems.

(2) Mechanically drive an APU mounted generator to run the standard aircraft electrical systems (typically produce 115 V alternating current (AC) at 400 Hz) and now to additionally supply electric...