Sensor is defined as an electronic device which is used to measure the physical and chemical quantity of substances and converts it in to the electronic signal that can be read by the Electronic Control Unit [ECU].
In vehicle, to collect data from different electro-mechanical devices and send the same to the control unit for vehicle control, driver safety, comfort and information and emission control sensors are required.
Sensor is an electronic device used in automobile to collect data from various systems or parts working in the vehicle. Sensor senses the physical or chemical amount of parts and sends it to the ECU. Sensors find its application in most of the automotive systems which include- Fuel supply system, cooling system, lubrication system, exhaust system, ac system, braking system, ignition system, steering, and suspension system.Modern vehicles uses number of micro controller based ECU and as such sensor has become a vital component for the automotive system. Accuracy, resolution, sensitivity and repeat ability are some of the main specification of the sensor.
There are different types of sensor working on the various principles like electrooptics, electromagnetic and piezoelectricity. Sensors are even defined as MEMs which stands for Micro-Electro-Mechanical system. Apart from the applications of sensor mentioned above, they are also useful to increase the vehicle and driver safety.
All sensors used in automobile work on four different principles:
1. Rotational Motion Sensor:
Rotational motion sensor measures the rotational speed of shaft. In automotive camshaft position sensor and crankshaft position sensor are the examples of rotational motion type sensor.
This type of sensor works on principles like variable reluctance, Hall Effect and magnetoresistor.
Engine crankshaft, engine camshaft, wheel speed can be measured with the help of rotational motion sensor.
2. Pressure Sensor:
This type of sensor works on the principle: "when pressure is applied to any part, electrical voltage is generated". This generated voltage is then fed to the ECU. Pressure sensor measures the pressure, ranging from 10 kPa to 180 Mpa.
This type of sensor works on piezo-resistive and capacitive principle.
Engine Absolute manifold pressure, engine barometric manifold pressure, turbo-boost pressure,and evaporative fuel leak pressure can be measured with the help of this sensor.
3. Temperature Sensor:
Temperature sensor generates voltage according to the temperature of part and sends it to the ECU. It can measure the temperature of part ranging from -100C to 10000C.
This type of sensor works on thermistor principle.
Engine coolant temperature and air intake temperature can be measured with the help of temperature sensor.
4. Linear and Angular Position Sensor:
Linear position sensor measures linear distance ranging from 2 microns to 200 mm. Angular position sensor measures the angular position of the components of the vehicle.
This type of sensor works on potentiometric, optical encoder and Hall Effect principle.
Fuel float level accelerator pedal angle and transmission gear position are measured with the help of linear and angular position sensor.