1. Sensors for recording operating conditions, which convert various material parameters into electrical signals.
2. ECU to generate output electrical signals based on signals from sensors and a given algorithm.
3. Actuators for converting the output electrical signals of the ECU into mechanical parameters.
Crankshaft speed sensor
1 - permanent magnet; 2 - casing; 3 - engine crankcase; 4 - metal rod; 5 - coil; 6 - toothed rotor
The position of the piston in the engine cylinder is decisive in determining the timing of fuel injection into the combustion chamber. Since the pistons are rigidly connected to the crankshaft through the connecting rods, the crankshaft position sensor transmits information to the control unit regarding the position of all pistons. An inductive yaw rate sensor determines the crankshaft speed and this important input variable is passed to the ECU.
The ferromagnetic rotor with 60 teeth is mounted on the crankshaft, while the rotor is missing 2 teeth. This gap is located in a certain position with respect to the crankshaft and the position of the piston in the first cylinder. The sensor is a permanent magnet and a metal rod with an inductive coil. When the rotor teeth pass near the pole of the sensor, a sinusoidal voltage is induced in it, the amplitude of which increases with increasing crankshaft speed.
Camshaft position sensor
The camshaft controls the intake and exhaust valves and rotates at half the speed of the crankshaft. As the piston moves to top dead center, the position of the camshaft indicates which piston is on the compression or exhaust stroke.
The camshaft position sensor works on the Hall effect. A momentary sensor signal tells the ECU that the No. 1 piston has entered the compression stroke.
Temperature sensors
1 - connector; 2 - body; 3 - NTC resistor
Temperature sensors are installed in various places in the engine and are designed to measure the temperature of the coolant, air entering the engine, engine oil and fuel returning to the fuel tank. At the heart of each sensor is a resistor whose resistance varies with temperature with a negative temperature coefficient (NTC). Voltage drop across the resistor through the analog-to-digital converter (ADC) transmitted to the ECU. The sensor response is stored in the ECU memory as a function of voltage.
Temperature sensor characteristic (NTC)
Air flow meter
1 – connector contacts; 2 - internal connections; 3 - electronic block; 4 - hole for air inlet; 5 – sensor element; 6 - hole for air release; 7 - body
The fuel injection system is designed for precise dosing of fuel depending on the amount of incoming air at various engine operating modes. The correct ratio of air and fuel is necessary to reduce the amount of harmful substances in the exhaust gases. This requires the use of sensors that accurately record the actual flow of air entering the engine's cylinders at any given moment.
The accuracy of the sensor should not depend on the pulsations, the exhaust gas recirculation system and the temperature of the air entering the engine. These requirements are met by a heated thin film air flow meter. A micromechanical measuring system registers the air flow and its direction.