Sukhpreet Singh JhajjMechanical Engg.Group 2Semester -8th

Sensors In Engine Management System

Sensors are the electronic components which sense for the different part of the engine and send the information to the Electronic Control Unit (ECU) For the further action.

What are Sensors?

Camshaft Position Sensor. Crankshaft Position Sensor. Manifold Absolute Pressure Sensor. Temprature Sensor. Knock Sensor. Lambda Sensor.

Different Type Of Sensors :-

It is used to identify the position TDC position of Cylinder No.1.

It is mounted on the cylinder head and works on camshaft.

The generated signals are used to turn power transistor off and on, which in turn switch the coils at proper time.

For gasoline and Diesel Fuel Injection System, the precision of the signal is very important to achieve high comfort and optimal performance.

Camshaft Position Sensor

Together with the speed sensor signal, the camshaft sensor signal supplies the absolute angular position of the crankshaft referred to TDC of the first fired engine cylnder.

It is unlikely that a failed camshaft position sensor will cause the engine to not start, as this particular sensor only times the injector pulses.

Cam shaft Position Sensor

The fuel injection system needs a reference to the position to the crankshaft in relation to rotational degrees. For this purpose, the CKP scans the toothed rotor mounted on the fly-wheel or small timing gear.

Crankshaft position Sensor

It is based on the induction principle, i.e induction coil senses alternation in the magnetic flow of the integrated permanent magnets relative to sensor wheel.

In order to meet the present and future emission limits and to achieve maximum comfort at ideal performance, the measurement of the engine speed must be extremely precise.

The signal precision is achieved via the high signal amplitude of the sensor and is still dependent on the design of the sensor wheel and on the application of engine system at engine.

Working

Crank Shaft Position Sensor

It is used to determine how much load is being placed on the engine. This is needed because if the load is heavy, more fuel must be injected to the engine. If the load is less, less fuel will be needed.

The manifold absolute pressure sensor provides instantaneous manifold information to the engine ECU. This is necessary to calculate air density and determine the engine air mass flow rate,which is used to calculate appropriate fuel flow.

The signal of the sensor is also used to determine the atmospheric pressure. For this purpose, the signals are evacuated with the engine stopped and when it is running at slow speed.

Manifold Absolute Pressure

Manifold Absolute Pressure

The temperature sensor measures temprature at or in the engine, e.g. The coolant circuit, oil circuit and fuel supply line and inlet air.

It is used to ON or OFF the radiator if the temperature of the engine increases to cool it.

Temprature Sensor

Temperature Sensor

Knocking is the process which occur when the ignition point is too far or advanced. Following the start of normal combustion, the considerable increase in pressure in combustion chamber leads to spontaneous ignition of the unburnt residual mixture not yet reached by the flame front.

Persistent knocking over lengthy period can cause mechanical damage to the engine on account of the pressure waves and increased thermal load.

Knock Sensor

It is located on the engine cylinder block. It senses vibration, which are then converted into electrical signal or sent to ECM for retarding the ignition timing to prevent damage to engine.

It is made up of piezoelectric material.

Knock Sensor

It is also called as Oxygen Sensor and is mounted at the outlet of exhaust manifold in MPFI vehicle. It detects the oxygen concentration in the exhaust gas and gives feedback to ECU to correct the air fuel ratio.

Lean mixture- High Oxygen content in exhaust gas. Rich mixture- Less Oxygen Content in exhaust gas. The Essential Constituent of the oxygen sensor is

special-ceramic body featuring gas-permeable platinum electrodes on its surface.

Lambda Sensor

Lambda Sensor

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