Air System Doesel Flashcards
What is Lead path?
Lead path helps to avoid short term interventions,thereby improve the response time of Air system.
Air system can calculate air requirement based on
Either torque or quantity depending on the project
What are the three blocks of Air system
Intake manifold(takes in air),
Engine,
Exhaust
Air filter in air system?
Filters contaminants and dust (filters more than 90% of Air )which might damage the engine.
Full form of HFM?
Hot-film air-mass sensor
What is the use of HFM?
Measures the air mass flow inside the intake manifold.
Also detects the aging of the HFM and adjusts its value accordingly.
Depending on how advance the HFM is also measure the temp and humidity of the air.
How does HFM work?
HFM has thin hot film which is heated to a constant temp, and whenever the air flows through it, the temp of the film decreases. So the amount of air entering is directly proportional to how much the film is cooling down.
Turbocharging has two parts, what are they?
Compressor and turbine
How does a turbocharger work?
It has two parts compressor and turbine,both are connected. Turbine is connected to the exhaust side and the compressor on the intake manifold, the exhaust gases move the turbine and which moves the air compressor and hence increase the speed of the air intake in the engine.
Volumetric efficiency
Volumetric efficiency 1 means the volume is completely utilised
Diesel engine is operated with volumetric efficiency of more than 1, how?
Air is compressed and filled in the engine.
After compression, the pressure of the air is how much
3.5 bar(3.5 time the atmospheric pressure)
CAC full form ?
Charge Air Coller
Why is there a need of CAC in air system?(2 reasons)
- To cool down hot air that was the result of compression so that this hot air does not go inside the engine, which can result in increase in high temperature, causing the formation of NOx.
- When the air temperature is less, density is more, you can accomodate more air in engine.
What is the difference between noise due to more cylinder?
More cylinder, smoother sound
Why emission control is hard in single cylinder vehicles?
Because in single cylinder, the value given by HFM is wrong as there is not a constant flow of air in the engine and hence the emission control in single cylinder engine is very tough.
Advantages and dis of filling more air in the cylinder of engines
Advantages: more volumetric efficiency.
Better compression and hence combustion.
Disadvantages
Unused air remains, resulting in formation of NOx.
EGR path
Exhaust gas recirculation path.
What is the advantage of recirculating the exhaust gas.
Increase the volumetric efficiency.
Does not react with fuel to form NOx. As NOx has the property to be formed on higher temperatures and exhaust gas reduces the overall temperature inside the engine cylinder.
EGRCLr, EGRVLv, ThrVlv,EGRClrByp
EGRCLr:Exhaust gas recirculation cooler.
EGRVLv: EGR valve
ThrVlv: throttle valve
EGRClrByp: EGR CooleR bypass
Turbocharger are made of two diffrent metals, what are they and why
Exhaust side(turbine) is made of Cast iron because it has to manage higher temperatures.
Inlet manifold side is made of aluminium alloy.
