EEC Temperature Control System
Publication Date: 2017-Mar-13
The IP.com Prior Art Database
The system described herein permits better control of the environment of engine-mounted electronic boxes, and more specifically the engine electronic control.
EEC Temperature Control System
The system described herein permits better control of the environment of engine-mounted
electronic boxes, and more specifically the engine electronic control.
As known in the field, a full authority digital engine (or electronics) control (“FADEC”)
includes a digital computer (often called an "Engine Electronic Controls” (EEC) or "engine
control unit" (ECU)) and its related accessories that control all aspects of aircraft engine
performance. FADECs have been produced for both piston engines and jet engines. The EEC is
a complex and critical component of the FADEC.
However, in certain type of jet engines, EEC units may fail at an unusually high rate,
which may be caused by the thermal cycling that occurs in a typical flight evolution.
Traditionally, the EEC is installed in a cold compartment around the aero-engine and is cooled
by ram air to survive the hot weather take-offs. In such traditional configurations, the EEC is
cooled on the ground by natural convection when the jet engine is off or at ground idle. On other
engines, when the engine is operating while on the ground, cooling air is drawn around the EEC
by the low pressure produced at the engine inlet.
During flight conditions, cooling flow for the EEC is provided by a ram air inlet. The
amount of cooling air is passively controlled by an orifice (or a venturi), part of the ram air inlet
system. As the aircraft accelerates to cruise speed, the amount of cooling flow increases, which
can cause two problems: a) overcooling the electronic circuitry at cruise and cracking of the
solder joints because of thermal fatigue, b) freezing of the condensed water within the EEC
pressure sense lines which may result in an unacceptable loss of thrust during cruise.
Thus, a typical EEC may experience in a single flight a range of ambient temperatures
between very cold at cruise (approximate range of -20 °C to 0 °C) to hot on the ground and low
altitude (approximate range of 70 °C to 90 °C) . Because of the extreme differences in these
operating temperatures, thermal expansion and contraction of the electronic components and of
the solder at the junction of these components to the circuit boards within the EEC occurs,
thereby leading to thermal fatigue and failure. Freezing in the EEC pressure sense lines may
cause an uncommanded loss of thrust.
When failure or temporary loss of thrust occurs, the EEC may need to be replaced at the
end of the flight; in some instances, the engine may even need to be shut down during the flight.
In any case, an engine maintenance action must occur. These situations are very costly to both
the airlines and to the engine/aircraft manufacturers due to flight disruptions, engine
maintenance, and component replacements. In-flight shutdown typically costs thousands of
dollars due to an aircraft having to land at a non-destination airport, and a back-up aircraft
having to be called or other form of transportation arrang...