I.C.S. ECU

Artesjet Microturbines

Description of the I.C.S.

The I.C.S. (Intelligent Control System) is a total system for the control of a model gas turbine engine. On the autostart version PERMITS A TOTALLY AUTOMATIC STARTING FROM THE RADIO CONTROLLER, now you can forget the problems starting your engine. Its main function is to control and regulate the fuel pump, providing to the turbine engine the necessary amount of fuel for safe and controlled operation. The I.C.S. measures the exhaust gas temperature, the relative position of the throttle stick and the rotor speed. It monitors all of the controls necessary to guarantee that the engine stays between the user defined parameters of operation, also providing failsafe shutdown of the engine when it has detected any important anomaly. In order to make this assessment, the I.C.S. has a rpm sensor, a thermocouple input, a throttle servo input, power connections for the fuel pump, starter, glow plug, fuel and gas valves and the battery and a digital (RS232) serial port to program and read the data in real-time to a PC.

The measurements made by the I.C.S. are:

· Temperature of the exhaust gas

· Pump battery voltage

· Width of the throttle pulses from the radio transmitter

· Engine rotor RPM

· Engine runs time.

· External analog signal.

All of these measurements can be read into and displayed on the Handheld Data terminal (HDT) that is connected to the I.C.S. by a RJ-45 connector, or into a personal computer trough a RS232 adapter. The configuration/setup parameters are stored in the I.C.S. by the terminal of hand or the PC.

Features:

· RPM input: Magnetic sensor up to 250.000 R.P.M.

· Temperature range up to 1000ºC using a "K" type thermocouple

· PWM control of 1024 levels for pump, glow plug and starter motor.

· Adjustable power for the starter motor

· Build-in electronic brake for the starter motor to help the clutch to disengage.

· Blown glow-plug detector

· Adjustable glow-plug power

· Glow-plug temperature independent of the battery voltage

· Adjustable gas off temperature

· Adjustable rpm starter switch on and off.

· Elapsed engine run timers

· Status LED on the unit plus 2 more remote on option

· RS232 interface to interface to a PC.

· Black box function. Record the engine measures each 0.5sec up to 52 minutes.

Adjusting the parameters:

On this software version there are 2 sets of parameters that can be changed.

The "user" parameters are adjustable trough the Data Terminal using normal menus. The "manufacturer" parameters are accessible by a special procedure and in some software versions, are only accessible by the manufacturers.

The user parameters are:

· Radio throws adjust.

· Maximum rpm

· Idle RPM

· Stop RPM

· Minimum temperature

· Maximum temperature

· Acceleration time

· Deceleration time

· Stability time

· Pump start point

· Pump start ramp

· Glow plug power

From these parameters, the readings of the engine and the position of the throttle control, the I.C.S. adjusts the power to the fuel pump in the following way:

First, the I.C.S. verifies that the control pulse of the transmitter is correct, that is to say, is between the limits set by the user. If the pulse is not correct, or the pulses are not received during 0.5 seconds, the system assumes that there is a trouble with the radio link and shuts down the engine (fail safe). During this time of delay, the system assumes that the throttle is at idle and decelerates the engine to this power.

Once verified that the pulse is correct, the relative position of the throttle stick determined by the limits programmed by the user is calculated. This calculation gives a value between 0% and 100% that can be read on the HDT or a PC. This value is transformed into a value of equivalent rotor speed from the values of full power speed and idle speed programmed by the user. For example, if we programmed an idle speed of 30.000 rpm and a full power speed of 100.000 rpm, this speed will be reached with the throttle control at 100%. With the throttle stick at 50%, the equivalent speed would be 65.000 rpm (half way between 30Krpm and 100Krpm). This calculated equivalent speed is compared with the one read from the engine and the power to the pump is corrected/adjusted until reaching the desired speed, in this case 65Krpm.

The speed of the slope of spool up is a parameter programmed by the user. To accelerate the engine the I.C.S. has to raise the power to the pump. The system monitors the exhaust temperature, reducing the rate acceleration if the temperature approaches to the maximum programmed temperature. In case of arriving at this maximum temperature, the system reduces the fuel flow until restoring the motor within its limits of operation, being able to stop the pump if it can not lower the temperature. With this system it is guaranteed that the engine accelerates in the minimum time possible without exceeding the max. Temperature or speed, adapting itself to the variations of the engine, room temperature, pump, fuel pressure etc.

With this system, called closed loop, the rotor RPM of the engine tracks linearly with the position of the throttle control, independently of the type of pump, batteries or engine. This benefit is very useful in multiengine aircraft, since the thrust of the engines is always in balance.

Aside from the safeguards of speed out of limits, temperature or radio failure, the system also incorporates two additional safeguards. First is pumping shutdown in case that the temperature of the exhaust is lower than the minimum, protecting the engine from flooding itself of non-burned fuel in case of flameout. The second is fuel pump shutdown due to a too low rotor speed. The system stops the fuel pump in case that the rotor speed is less than the programmed stop pressure. This safeguards the engine from continued running in case that rotor speed is less than that required to self-sustain the engine, or in an rpm sensor failure.

The engine can be started manually (semiautomatic) or full autostart system.

In order to start the engine in manual mode, the user must first raise the transmitter throttle trim and leave the throttle stick in idle/minimum position. The green Light Emitting Diode (LED) on the I.C.S. illuminates, indicating the system is "ready for start". Once in this position, the operator must 1) turn/spin up the engine with the starter motor / blower etc, 2) open the butane/propane gas, and ignite it. When the I.C.S. registers an exhaust temperature higher than the programmed start/minimum temperature and the rotor turning, the LED begins to blink and, 3) the system begins to pump fuel to the motor, raising the fuel pump power slowly until the idle speed is reached. This final condition is signaled by the system extinguishing the LED. The manual start is only possible after power-on the unit. If the throttle is cycled, the system enters in AUTO mode, and cannot be started in manual until it is switched off/on again.

To start the engine automatically, the user should cycle the throttle from idle to full power and back to idle again. In this moment the start procedure is triggered and the autostart sequence progress until the engine is at idle. The user can abort the start process by lowering the trim.

In the case that the measured exhaust temperature is higher than the start/minimum programmed temperature, the throttle stick acts a switch, allowing the starter to be energized and too cool down the engine after an aborted start.

A pump prime system is added. When, in the start phase, the throttle stick is set up to 100% during 5 sec, the pump is switched on at 25% of power for 1 second maximum. This allows priming the pump and the fuel tubes before the start.

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