Exhaust system of an engine

hi, I am sujon I just completed graduate at International University of Business Agriculture and Technology in Bangladesh Department of Mechanical Engineering

1. Welcome Presentation Topic: Exhaust System of an Engine Md Sujon Babu ID: 15207019

2. Contents Introduction of exhaust system Describe the parts and operation of exhaust system components Understand the operation of a muffler Understand the operation of a catalytic convertor Understand the operation of a Resonator Understand the operation of a heat shield Turbocharger and its operation Discuss about turbocharger Question-answer session

3. Introduction of exhaust system An Exhaust system is usually piping used to guide reaction exhaust gases away from a controlled combustion inside an engine or stove. The entire system conveys burnt gases from the engine and includes one or more exhaust pipes.

4. Introduction ( cont.) Depending on the overall system design, the exhaust gas may flow through one or more of Cylinder head and exhaust manifold A turbocharger to increase engine power A catalytic converter to reduce pollution A muffler or silencer to reduce noise.

5. Exhaust system fundamentals Exhaust system functions Carries burned exhaust gases away from the passenger compartment Quiets the engine Most new cars have one or more catalytic converters Excessive backpressure Reduces performance and fuel economy Exhaust system flow Not severely affected by bends in the pipe

6. Exhaust system fundamentals Mounted to cylinder head's exhaust ports Typically made of cast iron or steel Exhaust temperature Related to the amount of load on the engine Headers Aftermarket manifolds made of tube steel Sometimes require modification to install

7. Exhaust Manifold Fastens over the exhaust ports to carry burned gases into the exhaust system Connects the cylinder head exhaust ports to a header pipe Can be made of heavy cast iron or lightweight aluminum or stainless steel tubing

8. Exhaust Manifold

9. Exhaust system of an engine

10. Cross Flow Head This shows how the burnt gases comes out from the engine cylinder.

11. Exhaust pipes There are three types of exhaust pip Header pipe Intermediate pipe Tail pipe Usually made of rust-resistant tubing so we have to make sure the pipes are cleared of any obstructions and clogs.

12. Muffler Sheet metal chamber that dampens pressures pulsations to reduce exhaust noise. This is used conjunctions with a resonator. Service To ensure proper function, listen for a rattling noise when the car accelerates. Check for rust.

13. Muffler

14. Catalytic Converter An enclose, high temperature afterburner that consumes and chemically treats pollutants in the engine exhaust. An afterburner used to reduce the amount of exhaust pollutants entering the atmosphere One or more catalytic converter can be located in the exhaust system Types of catalytic converter Mini catalytic converter Two-way catalytic converter Three-way catalytic converter Dual bed catalytic converter

15. Catalytic converter

16. Resonator A resonator is a hollow chamber in the exhaust tract that creates a frequency of pulses that reverse the pulses coming down the exhaust pipe It works in conjunction with the muffler to quiet the exhaustion being emitted from the car Service Check for rattling to indicate loose pieces or debris build-up

17. Resonators

18. Heat Shield Metal plates that prevent exhaust heat from transferring to the fuel lines, floor, transmission and engine Located in areas where the exhaust system components are close to the vehicle’s body or near the ground The shields reduce the amount of heat transferred into the body and protect items under the vehicle Heat shields should be flat and not bent

19. Heat Shield

20. Exhaust system service Exhaust systems rust because of acids and moisture Exhaust gaskets suffer a good deal of abuse Header pipes collapse resulting in a restriction Tools used for exhaust work Chain-type pipe and roller-type exhaust cutters Pipe expander Deep sockets Chisel cutter Oxyacetylene torch

21. Damaged exhaust pipe

22. Turbocharger Small radial fan pump driven by the energy of the exhaust flow Helps a smaller engine provide more power Components and characteristics Centrifugal pump Diffuser and volute Size must match compressor Boost pressure: amount of air density provided Turbo lag: time required to bring the turbo up to a functioning speed

23. Turbocharger(Cont) Supercharged systems Use different ways to prevent excess pressure from accumulating Waste gate Prevents overpowering Internal and external Amount of boost can be changed Spring or boost controllers Valves Blow-off and compressor by-pass

24. Turbocharger(Cont) Variable geometry turbochargers Vary turbocharger geometry After cooler/intercooler Cooled by either air or water Turbocharger thrust/boost differential Occurs when pressure is higher in either the turbine or the compressor Turbocharger parts Bearings, turbine shaft, compressor, turbine wheels, and housings

25. Function of Turbocharger A turbocharger is a turbine driven forced induction device that increases an internal combustion engine’s efficiency and power output by forcing extra air into the combustion chamber. This improvement over a naturally aspirated engine’s power output is due to the fact that the compressor can force more air and proportionately more fuel into the combustion chamber than atmospheric pressure alone .

26. Functions of turbocharger parts Boost Threshold The boost threshold of a turbocharger system is the lower bound of the region within which the compressor operates. Below a certain rate of flow, a compressor operates. Below a certain rate of flow, a compressor produces insignificant boost. This limits boost at a particular RPM, regardless of exhaust gas pressure. Newer turbocharger and engine developments have steadily reduced boost thresholds. Turbochargers start producing boost only when a certain amount of kinetic energy is present in the exhaust gases. Without adequate exhaust gas flow to spin the turbine blades, the turbocharger cannot produce the necessary force needed to compress the air going into the engine.

27. Functions of turbocharger parts(cont.) Turbine The turbocharger turbine, which consists of a turbine wheel and a turbine housing, converts the engine exhaust gas into mechanical energy to drive the compressor. The gas, which is restricted by the turbine’s flow cross-sectional area, results in a pressure and temperature drop between the inlet and outlet. This pressure drop is converted by the turbine into kinetic energy to drive the turbine wheel.

28. Functions of turbocharger parts(cont.) Compressor Turbocharger compressors are generally centrifugal compressors consisting of three essential component: compressor wheel, diffuser, and housing. With the rotational speed of the wheel, air is drawn in axially, accelerated to high velocity and then expelled in a radial direction. The diffuser slows down the high-velocity air, largely without losses, so that both pressure and temperature rise. The diffuser is formed by the compressor backplate and a part of the volute housing, which in its turbine collects the air and slows it down further before it reaches the compressor exit.

29. Functions of turbocharger parts(cont.) Center Housing/ Hub The center hub rotating assembly (CHRA) houses the shaft that connects the compressor impeller and turbine. It also must contain a bearing system to suspend the shaft, allowing it to rotate at very high speed with minimal friction. For instance, in automotive applications the CHRA typically uses a thrust bearing of ball bearing lubricated by a constant supply of pressurized engine oil. The CHRA may also be considered water-cooled by having and entry and exit point for engine coolant. Water-cooled models use engine coolant to keep lubricating oil cooler, avoiding possible oil coking from the extreme heat in the turbine. The development of air-foil bearing removed the risk.

30. Turbocharger (Troubleshooting) Turbocharger balance Turbo spin in excess of 100,000 rpm and are balanced to run in excess of 150,000 rpm Turbocharger replacement Not usually attempted in repair shops Turbocharger troubleshooting Common failures: blockages, leaks, and foreign object damage

31. Turbocharger( Troubleshooting ) Diagnosing damage to a turbo Turbine damage Broken piston rings, valves, or pistons Compressor damage Results from objects entering the intake Thrust bearing failure Not common