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| EGR SYSTEM |
EGR SYSTEM AND ITS USE
EGR (Exhaust Gas Recirculation) system is reducing the combustion temperature of an engine by small amount of an exhaust gas taking from an engine and back into the engine. EGR system has come to reduce the NOx or pollution by reducing the temperature of combustion engine. EGR works by recirculating a portion of an engine's exhaust gas back to the engine cylinders. This dilutes the O2 in the incoming air stream and provides gases inert to combustion to act as absorbents of combustion heat to reduce peak in-cylinder temperatures.
NOx is produced in high temperature mixtures of atmospheric nitrogen and oxygen that occur in the combustion cylinder, and this usually occurs at cylinder peak pressure. Another primary benefit of external EGR valves on a spark ignition engine is an increase in efficiency, as charge dilution allows a larger throttle position and reduces associated pumping losses.
EGR valve is fitted in BSIV and BSVI vehicle to reduce temperature as well as pollution. EGR valve is a spring loaded valve work on the basis of temperature when the temperature reached at 100*C then EGR valve open and take the gas coming from combustion chamber about 20% and mix with fresh air coming from air filter then back into the combustion chamber by it reduce the temperature of an engine. EGR valve connected with exhaust line and intake manifold. It is located near the intake manifold.
Main part used in EGR system is.
· EGR valve
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| EGR VALVE |
· EGR cooler
EGR valve- The EGR valve is a small component designed to allow the flow of exhaust gases into the intake manifold in controlled amounts. As such, it's a simple valve that closes and opens as needed.
The EGR valve has one single job to do, regardless of the system configuration, type of control and number of sensors: that is, to either open or direct exhaust gases into the combustion chamber, or to close and keep them from entering.
Whenever you start the engine, the valve comes alive and waits in a closed position, blocking the flow of exhaust gases.
Once the engine reaches operating temperature and speed increases, the valve—either through vacuum or electronic control gradually opens, allowing burned exhaust gases to enter and combine with the air-fuel mixture inside the combustion chamber. If you slow down sufficiently or come to a stop, the valve gradually closes and blocks the flow of exhaust gasses. And the process continues for as long as the engine is running.
After you shut off the engine, the EGR valve closes and remains in that position.
Main function of an EGR valve controls the flow of exhaust gases from the exhaust manifold into the intake manifold. EGR valve control by the ECU (electronic control unit) The EGR valve is normally closed. It's also closed when the engine is cold, at idle, or under hard acceleration. The EGR flow is at its peak during steady cruising. The EGR system flow is monitored by several sensors.
Symptoms of failure EGR valve- Actually there are two kinds of bad EGR valves, with different symptoms. An EGR valve can fail in two ways: It can be open all the time, or it can be closed all the time and other symptoms are.
· a smell of fuel
· increased fuel consumption
· pinging, tapping, or knocking sounds
· failed smog test
· Check Engine Light on
EGR cooler- The EGR cooler is a component used to lower the temperature of the exhaust gases that are recirculate by the EGR system. The EGR system recirculates exhaust gases back into the engine in order to decrease cylinder temperatures and NOx emissions.
EGR COOLER
An EGR cooler works to improve a vehicle’s overall performance by cooling the exhaust gas before it’s recirculate into the intake manifold. This has the benefit of reducing the combustion temperature, thereby preventing valve clatter and detonation. It also reduces the amount of NOx gases produced, since the combustion chamber does not reach the temperatures required for excess levels of NOx gases to form.
EGR cooling is usually facilitated through the circulation of engine coolant through the EGR as a heat exchange medium. The overall size and type of EGR cooler made available in a vehicle depends on the engine size as well as the emissions standard the engine must remain in compliance with.
Symptoms of failure EGR cooler-
One of the first symptoms of a potential problem with the EGR cooler is engine overheating. If the EGR cooler has any issues that restrict the flow of exhaust gases through the cooler it can cause the engine to overheat. Over time, carbon can build up on the inside of the EGR cooler and restrict flow through the cooler. And other symptoms are given below.
· Engine overheating
· Exhaust leak.
· Check Engine Light comes on.
Engine overheating-
If the EGR cooler has any issues that restrict the flow of exhaust gases through the cooler it can cause the engine to overheat. Over time, carbon can build up on the inside of the EGR cooler and restrict flow through the cooler. This can cause the unit to overheat, at which point it will not be able to cool the exhaust gases, and the engine will overheat as a result. Engine overheating can lead to knock or ping from the engine, and even serious damage, if the issue is left unattended.
Exhaust leak-
Another issue of a problem with the EGR cooler is exhaust leaks. If the EGR cooler gaskets fail, or the cooler gets damaged for any reason, it can cause an exhaust leak to develop.
Check Engine Light comes on-
Another symptom of a bad or failing EGR cooler is a Check Engine Light. If the computer detects a problem with the EGR system, such as insufficient flow or exhaust, it will set off the Check Engine Light to alert the driver of the issue. A Check Engine Light can also be set off by a wide variety of other issues, so having the computer scanned for trouble codes is highly recommended.
EGR coolers are not found on all vehicles, but for the vehicles that are equipped with them they are critical to the performance and drive-ability of the vehicle. Any problems with the EGR cooler can also lead to increased emissions, which will be a problem for states that require emissions testing for all of their vehicles. For this reason, if you suspect that your EGR cooler may be having an issue, have the vehicle inspected by a professional technician, such as one from Your Mechanic, to determine if the cooler should be replaced.
External link-
cooling system in vehicle
https://indiastudy2.blogspot.com/2020/05/cooling-system-engine-cooling.html
https://indiastudy2.blogspot.com/2020/05/cooling-system-engine-cooling.html
Sensor used in vehicle
Brake and its Type
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