If the engine is the car’s heart, the controller ought to be the brain, and today we are going to understand it better.
The ancient controllers date back to late 70s, and they rose because of the American government policies of reducing polluting gases. Therefore manufacturers looked for new alternatives in automotive, and thus was born the Engine Control Unit – ECU.
This device allows to control electronically what was done with mechanical and pneumatic systems such as carburettors or injection pumps, being able to control in a more effective way the combustion engine.
Big picture of a straight-six engine (L6) and its ECU main diagram.
Depending on the technology, the ECU can take information from one or another kind of sensors, compare data with the settings you have programmed on its internal memory and decide the orders to give them to the actuators that control the engine. This also let us increase the functions that are assigned to this small computer, adapted to the needs of each vehicle.
In our case, for controlling a Honda CBR 600 RR engine (our heart), assembled on the new ART-16 with our own designs of the intake, exhaust and cooling system, we need to get a programmable ECU, as the original unit is optimized to be used with the CBR standard parts.
We use the Link G4+ Storm, which is fully programmable and comes with its own software. It allows data logging of both analog and digital sensors. It is designed in order to control a 4-strokes engine and also has extra inputs and outputs to add new features.
PC Link software interface example.
SENSORS AND ACTUATORS
The most common sensors that an ECU reads are:
- CKP (Crankshaft position): Gives crankshaft position.
- CMP (Camshaft position): Gives the camshaft position.
- WS (wheel speed): Gives the gear speed to the output of the engine block, which is related to the vehicle speed provided while no skidding.
- EOT (engine oil temperature): Gives exactly what it says.
- ECT (engine coolant temperature): Gives the coolant temperature.
- Lambda sensor: Oxygen concentration in the exhaust gas, which represents the degree of richness of the air/fuel mixture.
- MAP (manifold absolute pressure): Indicates the gas pressure in the intake manifold (ours car “nose”).
- IAT (intake air temperature): Indicates the air temperature in the intake manifold.
- KNS (knock sensor): It indicates the time of the engine knock.
- TP (throttle position): It indicates the position of the throttle, measured on the admission butterfly (hole “nose” that opens or closes when the driver presses the accelerator pedal).
And the main actuators to keep the engine at peak performance are:
- Ignition coils: Control of ignition of 4 spark plugs.
- Injectors: Injectors opening control.
- Fuel: Control the fuel pump.
In our case we also control the fan in the cooling circuit.
COMMUNICATION AND USE OF DATA
This ECU allows to log data. It stores information from all sensors to be analysed later in the computer, which allows you to track down engine stalls, misfires or other undesired behaviours.
The unit also allows you to take data in real time via CAN Bus, which is a communication protocol to transmit messages between distributed systems. In our case we communicate the ECU, the display and the DAQ (data acquisition board) by CAN Bus to show information to the pilot while we use telemetry or we save data on-board.
All this makes it the perfect ECU for our task. Do you know something better? We keep working hard!