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About this book

This book is intended to serve as a comprehensive reference on the design and development of diesel engines. It talks about combustion and gas exchange processes with important references to emissions and fuel consumption and descriptions of the design of various parts of an engine, its coolants and lubricants, and emission control and optimization techniques. Some of the topics covered are turbocharging and supercharging, noise and vibrational control, emission and combustion control, and the future of heavy duty diesel engines. This volume will be of interest to researchers and professionals working in this area.

Table of Contents

Frontmatter

Chapter 1. Introduction

Abstract
The book is on design of diesel engines. The engine design is motivated by advanced emission standards, and yearning for fuel economy as well as downsizing to achieve light weight. The book develops the subject gradually by discussing various topics so that it is useful to a practising engineer and a student intending to develop a career in engine design. The book is broadly divided into five parts after introduction. The introduction chapter summarises the book after giving some thoughts on estimating the power, maximum torque and shape of the torque curve to satisfy vehicles on- and off-road.
P. A. Lakshminarayanan, Avinash Kumar Agarwal

Thermodynamics, Combustion, Gas Exchange, Emissions

Frontmatter

Chapter 2. Modern Diesel Combustion

Abstract
The chapter begins with the historical development of diesel combustion and explains engine Combustion Mechanisms followed by Fuel Injection and Supercharging. It explains the important step in the evolution of engine design to reduce NOx by Exhaust Gas Recirculation. Apart from the popular systems there are also Alternative Diesel Combustion Systems to remember. The evolution of the diesel engine is undoubtedly driven by the legislative standards for the Emissions of Internal Combustion Engines. The real concern regarding Global Climate Change imposes the limit to carbon dioxide and hence indirectly the fuel consumption. The particulate affective animal breathing systems as well as global warming is controlled tightly. This calls for accurate measurement of Particle Number. Apart from gaseous emissions, there is also a cap on the noise emissions. Al these requirements are satisfied to a large extent by the use of sophisticated air flow and fuel injection inside the engine. However, the advanced emission norms are satisfied only if there is Exhaust Aftertreatment to abate Nitric oxides and particulates. Hard working large engines have heat recuperation systems to consume the exhaust and coolant heat usefully. For carrying out this work, the losses have to be estimated correctly. To save cost and noise, many times the diesel engines are converted to operation on neat gas. For development of a country’s infrastructure the diesel engine is being further developed to compete with other power sources as the engine is advantageous regarding logistics, storage, efficiency and compactness.
Walter Knecht, P. A. Lakshminarayanan

Chapter 3. Supercharging

Abstract
Historically, diesel engine was supercharged to increase power. The charger was run by mechanically by the engine crankshaft. This enabled airflow as a function of engine speed, ideal for a piston engine. However, as it would, it wasted a lot of exhaust energy and turbocharging was invented where the turbine driven by the exhaust gases drives the compressor. This has its own problems like mismatch in air flow in terms of lower airflow than required at lower speed range and higher airflow at higher speed range. This was resolved by various techniques. The easiest, but not the most efficient, method is waste gating the turbocharger. Variable turbine entry turbocharger, two stage turbocharger and other ingenious solutions increased the overall efficiency of the engine and improved the power to weight ratio of the diesel engine. Surging, wheel speed and choking are the boundaries of operation of a turbo compressor. The boundaries are stretched by new designs of the compressor wheel. With the advent of electronics intelligent control of turbocharger enabled enhancing the airflow in the low speed range and hence the engine torque. Charge air cooling plays an important role in increasing the air flow, reducing nitric oxide emissions as well as the power. The development of turbochargers is continuing with new concepts that enhance power, engine efficiency as well as emissions.
Walter Knecht, P. A. Lakshminarayanan

Chapter 4. Introduction to Turbocharging—A Perspective on Air Management System

Abstract
This chapter provides an introduction to air management system with an emphasis on turbocharging, its role in emissions, fuel economy and performance. A typical turbocharger has a radial turbine run by the exhaust gas (thus extracting useful energy) which in turn spins a compressor that compresses air drawn from the atmosphere through the intake system. Sending compressed air into the engine allows more fuel to be burnt within the same volume, increasing the efficiency of the engine (lower surface area means lower frictional and heat transfer losses). In other words, a turbocharger could be used to “downsize” the internal combustion engine, with reduced losses. It is also accompanied by reduced emissions since the air flow could be increased as desired with a turbocharger.
D. A. Subramani, R. Dhinagaran, V. R. Prasanth

Chapter 5. Topics on Selective Catalyst Reduction

Abstract
SCR concept is used effectively in large electric power stations to abate nitric oxides for the last fifty years. Here, simpler controls to inject ammonia in the engine exhaust over a catalyst were enough since the change in emission was only with respect to load and slow. However, application of this technique to truck and car engines was challenging and invited control and thermal problems. This chapter, after introducing the chemical technology goes in depth, explaining the engine optimization for SCR technology, the trade-off of NOx and soot, and rail pressure and timing. The principle of NOx reduction is explained using NOx model with maps of exhaust flow, storage of ammonia in the catalyst and dosing ratio. A temperature model is essential for precise control of nitric oxides. Also, a model for hydrolysis of urea to ammonia and accelerated reaction rates in the presence of nitrogen dioxide is given to consider upstream diesel oxidation catalyst that not only increases the concentration of nitrogen dioxide but also oxidizes carbon monoxide as well as hydrocarbons. Understanding the specification and salient properties of urea solution is important for the success of the SCR technology. In the highly transient thermal environment, there are various types of potential failures due to creep, thermal stress and flow stress. Further, the hydrolysis of urea just after injection, nozzle clogging, crystallization in the catalyst, ammonium di sulphide plugging, active catalyst surface plugging, poisoning due to high sulphur in the fuel as well as potassium and other alkali metals from lubricating oil and other flow phenomenon are studied for the longevity of the SCR system in the engine with the optimally located urea injector. Airless injection system does away with the need for compressed air which is necessary for air assisted injection system; however, distribution of urea and its hydrolysis in the flow is more complex and hence more detailed design analysis must be carried out. Continuous development and tightening of emission limits call for Cu or Ze based catalyst that lights off at a lower temperature than the cost-effective and sulphur tolerant vanadium-based catalyst. Choice of metallic or ceramic catalyst substrate creates an intense dilemma between cost, manufacture, thermal response, and life. Coated or extruded catalyst is again a design trade-off. The high-speed electronic control or the dosing control unit communicates with engine management system. The entire application exercise involves in modelling the storage, reaction and slip of ammonia over the catalyst for transient cycles. Therefore, some companies have preferred exhaust gas recirculation which is less fuel efficient than SCR. SCR in emerging markets has its own challenges and advantages. There are challenges in the field regarding dosing system failure, HC poisoning, catalyst wash out, reliability of NOx sensors. Application of SCR calls for long duration field trials at varying loads, at high altitudes and temperatures which are either not envisaged in the engine laboratory or not possible to simulate easily.
P. Kumar

Chapter 6. Strategies to Control Emissions from Off-Road Diesel Engines

Abstract
With advancement of societies, travel over short distances in traffic snarls or long distances at high power is becoming common. Also, diesel engine is the main workhorse of the fast industrialising globe, for building infrastructure, and improving comfort. The increase in engine population working in different duty cycles, has caused rise in emissions in spaces where large population is concentrated. As emission standards are progressively raised worldwide to combat this problem, advanced and complex diesel engines are designed to meet the specifications; hand in hand, testing diesel engines according to operating cycles defined as functions of the types of duties, has become more and more sophisticated. For on-road operations, the testing cycles of different nations are becoming harmonised to avoid multiplicity of certification tests or of engine calibrations. There are many harmful chemical compounds, mainly in gaseous form in the engine exhaust; those that are in minute traces and can be healed by the nature, are not regulated; on the other hand, nitric oxides (NOx), carbon monoxide, total hydrocarbons, particulate matter (PM) which are in large concentrations, are regulated tightly. Carbon dioxide as a significant contributor to global warming is regulated indirectly by placing a ceiling on the corporate average consumption of fossil fuels. Diesel is known for NOx formation in the high temperature zones of diesel spray, and for creation of PM in rich cold regions of the spray. In this chapter, the impact of various parameters of operation and design, is explained in the context of diesel engines, to enable devising control strategies such as turbocharging, intercooling, exhaust gas recirculation, and water injection, or aftertreatment systems like selective catalytic reduction, diesel oxidation catalyst, and diesel particulate filter are discussed in detail.
M. V. Ganesh Prasad

Chapter 7. External Exhaust Gas Recirculation

Abstract
In diesel engines, NOx (Oxides of Nitrogen) forms when the flame temperature in the combustion chamber exceeds 2000 K. Late injection of fuel into the combustion chamber decreases NOx at the cost of fuel efficiency by 10–15%. Recirculating a part of the exhaust gas into the combustion chamber is termed as exhaust gas recirculation (EGR) which helps in reducing NOx with a particulate trade off. Diesel oxidation catalyst and a particulate filter are, therefore, necessary to reduce the particulate. In this chapter, the complex interactions between the EGR, turbocharger, EGR cooler, air fuel ratio, combustion efficiency and pumping work are described. It is shown that EGR provides an effective means for reducing flame temperatures and NOx emissions, particularly under lower air fuel ratio conditions. Combustion deterioration is predominant at higher load, low speed and lower boost conditions due to a substantial reduction of air fuel ratio with EGR.
P. Sahaya Surendira Babu, P. Kumar

Chapter 8. Diesel Particulate Filter

Abstract
The development of automotive emission control technology over the last five decades is one of the greatest environmental success stories of this century. Innovation of Catalytic Converter in 1970 changed the emission scenario worldwide. Later on, Diesel Particulate Filters (DPFs) were innovated in 1985 and were commercialized in the year 2000 to control diesel engine out particulates. Particle Number emission limit came under regulated mass emissions after Euro 6 standards. Diesel Particulate Filters is an effective after treatment device to control Particulate Matter and Particle Number. In this Chapter, Diesel Particulate Filters have been elucidated with reference to their function, construction, working, substrate, wash coat, catalyst and canning technology. The Design Considerations with reference to geometrical, mechanical and thermal properties are explained. Influence of various constraints and factors effecting the performance of these After-treatment devices such as air-fuel ratio, exhaust and light-off temperatures, conversion and filtration efficiencies, space velocity and poison concentrations are discussed and the impact of fuel and lubricating oil quality have also been summarized. The different DPF failure modes with their causes and regeneration methods are classified in this chapter. Factors affecting DPF performance and general performance criteria for DPF are discussed in-depth. Diesel Particulate Filter validation plan, performance testing and certification criteria is highlighted in this chapter. Catalysed-DPF, Continuously Regenerating Trap (CRT), methods of servicing of DPF and various recent research advances in DPF have been explained in detail. Different types of tests used to evaluate them have been highlighted and their optimization, performance and durability have been explained. Regeneration, innovation in fuel injection and controls, etc. have been discussed in detail.
K. C. Vora, Kartik E. Gurnule, S. Venkatesh

Chapter 9. Conversion of Diesel Engines for CNG Fuel Operation

Abstract
The objective of converting a diesel engine to neat CNG operation is manifold. To achieve very low emissions without complex equipment, use alternative gaseous fuel available in countries which have only expensive access to liquid fuel and not the least emit relatively lower carbon dioxide. The lean burn combustion strategy has been the darling some extreme designers claiming improved efficiency and reduced nitric oxides. Though the improvements could be shown in the laboratory in practical conditions, the difference was either negligible or counterproductive. In addition, treatment of NOx in lean conditions was a big challenge. Therefore, almost all the designers have switched to stoichiometric combustion. Transient control of stoichiometry is easier when port or manifold injection is practiced instead of carburation. Again, high voltage electronic ignition system with smart spark timing management, goes a long way in controlling combustion and emissions. Long life spark plugs of high heat rating with integrated ignition coil not only simplifies the design but also enhances the voltage at the spark plug by reducing losses. The engine modifications by redesigning the piston, cylinder head, exhaust valve system and manifolds, and introduction of gas and ignition system, cooling system and turbocharger are carried out meticulously. The vehicle is adapted for the CNG system consisting of the storage cylinders, high pressure tubes, pressure regulator and gas filter. The thermal efficiency and emissions of the engine is improved by reduced throttle losses and using a simplified EGR circuit. This chapter will provide the general guidelines for converting a diesel compression ignition engine to spark ignited compressed natural gas engine. An example is provided to convert a diesel engine to a state-of-the-art natural gas engine with computer controlled multipoint injection.
G. Jeevan Dass, P. A. Lakshminarayanan

Chapter 10. Simulation of Gas Flow Through Engine

Abstract
Modern diesel engine has to meet both legislative and customer requirements simultaneously. Engine sub-systems are required to be precisely matched considering their interactive effect. It is a costly and time-consuming task if done experimentally. This task is becoming more complex due to flexibility in the advanced subsystems, which makes optimum matching of the subsystems practically becomes impossible. Use of simulation tools is very effective to handle this complexity and has advantage of significantly lower development time and cost. 3D CFD and 1D thermodynamic simulation tools are effectively used to analyse and tune engine subsystems performance. This gives opportunity to tune sub-system performance with their interactive effects, without a need of making physical prototypes. Considering the execution time, 1D thermodynamic simulation tool is more useful in the early stage development of the engine.
Neelkanth V. Marathe, Sukrut S. Thipse, Nagesh H. Walke, Sushil S. Ramdasi

Design of Engine Build

Frontmatter

Chapter 11. Development of Ports of Four Stroke Diesel Engines

Abstract
Fresh air is breathed in and products of combustion are exhaled by the inlet and exhaust ports. The efficiency of air flow is given by the flow coefficient. The flow is turbulent for most of the period and avoiding recirculation zones improves the flow. The energy for the flow is imparted by the piston during the intake stroke and only partly in the exhaust stroke as blowdown is a significant contributor during exhaust process. The energy during intake is partitioned between components contributing to flow and to swirl, which is important to support combustion in a direct injection engine. Of all the types of intake ports producing swirl in the cylinder, helical port is amenable to theoretical treatment with less empiricism; also, a helical port is stable in production and highly efficient. Helical port design considers free vortex with a correction for friction at cylinder liner surfaces. The optimum helical port is one which minimises the variation of exit velocity about the periphery of the valve seat. The exhaust port is designed to accelerate the flow at zones where there is a tendency to separate and then, a diffuser is designed to gain pressure. The definitions for the flow coefficient and swirl number vary from institution to institution. The definitions followed in this chapter were pioneered by AVL; these are widely used in many countries as de facto standard. The engine swirl can be reproduced at steady state rig for benchmarking or tuning the ports designed based on theory.
Nagaraj S. Nayak, P. A. Lakshminarayanan

Chapter 12. Design and Analysis Aspects of Medium and Heavy-Duty Engine Crankcase

Abstract
The crankcase is the base part to which all important parts of an engine are assembled inside and on to it. The structure though is apparently stationary, it transmits or receives highly fluctuating loads at high frequency, from the piston, crankshaft and different pumps and gears inside it, and through bolt holes, its walls, ribs and surfaces mating with the other components. It enables the piston movement and wears out over the period of its maintenance life. The subject on crankcase is vast and an attempt is made in this chapter to describe the design and development of this basic part, with sufficient peer references. To construct a crank case of a heavy-duty diesel engine, materials of choice are grey cast (GJL), vermicular (CJL) and ductile irons (GJS). The physical and mechanical characteristics of grey, vermicular and ductile cast irons are tabled for use in various calculations. The strength of the material, basically affected by alloying elements and their effect on phase transformation and material properties is given with reference to the basic iron carbon equilibrium diagram. The resulting material properties specific to application like shock, vibration, fatigue and heat transfer are given. The cylinder liner may be integral with the crankcase or separate depending on the philosophy of design and application. The liners are classified as dry liner and wet liner; the latter can be either having a stop at the top or at the middle. The wear of the liner especially by the high contact pressure of the rings at the top and bottom dead centres is controlled by providing sufficient oil film thickness without much carryover past the piston to the combustion chamber. The surface is carefully honed where the type of honing is a choice after balancing the cost and required performance. The liner thickness is designed by not only considering the strength but also stiffness against cavitation. The design of a liner, in general, ponders over the failure modes like liner fillet cracking, bore distortions, bore polishing and, in case of wet liner, cavitation. The functionalities of the bays like crankcase top deck, between the cylinders, crankcase bottom and main bearing cap, crankcase front end and crankcase rear end are taken care of while designing the crankcase. While laying out the top deck, the following important parameters are studied: gasket sealing, crankcase top stiffness, cylinder head bolts and cone of compression, deck cooling by CFD analysis, brinelling and indentation, fretting, oil-hole management, and bore distortion. Similarly, while designing bays between the cylinders, the parameters to be considered are coolant heat transfer, flow velocity, cavitation, crankcase ventilation, piston secondary motion and NVH. The important parameters while planning the bottom and main bearing caps are the assembly aspects, strength against firing and inertia loads, high cycle fatigue of crankcase and main bearing caps, main and side bolt fatigue, fretting at crankcase at the bearing cap interface and NVH aspects. The front end is constructed by considering the mounting components, and NVH by carrying out modal analysis; the bearing crush, radial loads, sealing methods, main and side bolt placement are some of the important aspects borne in mind. On the flywheel end of the crankcase, locating the flywheel housing, oil seal housing design as well as NVH are the aspects to take care. The design is validated experimentally at the hydro-pulsation rig. Finally, the success of the design is very dependent on the quality of production.
Swapnil Thigale, M. N. Kumar, Yogesh Aghav, Nitin Gokhale, Uday Gokhale

Chapter 13. Connecting Rod

Abstract
The connecting rod converts the reciprocating motion of piston into the rotating motion of the crankshaft. Generally, it can be seen in three parts, i.e., small end, shank and big end. The connecting rod motion is complex as the small end is reciprocating along cylinder axis and big end is rotating along with the crankpin. The Loads on a connecting rod are categorized as three types namely, Firing load, Inertia load and other loads. The analysis of loads on Connecting Rod by classical method must be carried out for sizing and shaping before going for detailed analysis using the finite element method for both static and dynamic loads. The examples for the classical method are available in the appendix. The analysis for the four load cases namely, Bolt Preload and Bearing and Bush Interference, Gas Pressure Loading, Inertia Loading and Combined Loading is presented. Enhancing the yield strength and fatigue strength is achieved by choice of Materials and heat treatment. Some practical aspects during design like Weight grouping of connecting rods, Push-out force test and Testing of the connecting rod are given. The fracture splitting method for connecting rods is becoming popular as an exercise in cost reduction. The manufacturing process of connecting rod is described in brief. At the end of the chapter various failure modes are described which are borne in mind while designing the connecting rod.
Prakash R. Wani

Chapter 14. Critical Fasteners, Highly Loaded Bolted Joints

Abstract
Due to clamping of the parts, the compressive stress is induced at the joint surface. The compressive stress keeps the joint away from opening out. The reliability of the joint depends on what is the reliability of the fasteners geometry, correct material selection and heat treatment, reliability of load analysis and reliability in achieving expected joint clamping load during assembly of the relevant parts. In this chapter, the preload on critical fasteners is explained using the force diagram of a bolted joint and the settling force, pre-loading on the bolts and tightening by torque-controlled tightening, angle-controlled tightening and other methods is described in detail. Important practical aspects like thread engagement length, limiting surface pressure and fatigue loading are dealt with at length. The influence of temperature especially in cylinder head bolts is important to consider while designing. The high temperature fasteners form a special category in design and development. Various methods to improve the fatigue strength of the joints are given. The time-honoured design process as per VDI 2230 is explained and examples are provided in the appendix. Also, the typical failure modes for which the design work is carried out are provided.
Prakash R. Wani

Chapter 15. Crankshaft

Abstract
A crankshaft is used to convert reciprocating motion of the piston into rotary motion. The crankshaft in an engine is probably the most complex of all the shafts used in any machinery, and, as the name implies, it is far from being anywhere near a straight shaft. With the help of examples, crankshafts are classified depending on the type of supports as overhung and centre crankshaft or based on the number of throws as single throw or multi-throw shafts. The procedure for design the crankshafts is explained in detail using calculations of the crankshaft strength and stress. The factors affecting the fatigue strength are deliberated. Plots of oil film thickness explain the wear pattern. Inherently, single-, two-, three- and four- cylinder in line engines are not fully balanced for inertia forces or couples; if the cost permits, counter rotating balance shafts are designed to neutralize these forces. Otherwise, these forces are left unbalanced; they cause rigid body vibration of the engine and also are transmitted to the vehicle and to other parts. Vee engine shafts are treated slightly differently from the inline engine shafts. The designed shaft when made does not have mass distribution as per the design because of manufacturing tolerances to forging and machining. This imbalance is removed at a balancing machine within the limits specified in standards. The inertias of individual throws, piston, and connecting rod as well as the flywheel with the stiffness of the shaft result in multiple natural frequencies in the rotational direction. In case of long shafts as in the case of a six-cylinder engine, the torsional vibration can have a resonance frequency in the operating range of speeds and can induce fatigue usually starting from the oil hole in crank pin. Therefore, calculations of moments of inertia, equivalent stiffness and the natural frequencies as well as the amplitude of vibration are important. If the amplitude is sufficiently high, the torsional stress can exceed the fatigue strength limit leading to failure. To avoid the natural frequency in the speed range of operation an oscillator in the form of a torsional vibration damper is added. The new system not only shifts the frequencies but al-so reduces the dynamic magnifier to reduce the torsional stresses. Various parameters like characteristic frequency at fixed points, damping ratio, unit tuning ratio, optimum tuning ratio are introduced and with the aid of a characteristic help-graph, the tuning ratio of a rubber or spring damper can be selected. While rubber is relatively less expensive, heat dissipation in the damper must be carefully predicted to estimate the temperature of the rubber in the damper as the properties of rubber are highly dependent on temperature. The type of rubber is properly selected and manufactured with great care to avoid aging of rubber at the operating temperature. When the heat may not be easily dissipated fluid dampers are useful. Such dampers without a spring only dampen the vibration to save the shaft but do not play any major role in shifting the natural frequency of the shaft system. The engine load can be quickly simulated at specific rigs to estimate the bending fatigue or torsional fatigue. Finally, the importance of the design of bolts and the applied tightening torque are important to hold the flywheel, the crank pulley, connecting rods, bearing caps together, cannot be understated.
Prakash R. Wani

Chapter 16. Gaskets

Abstract
This chapter describes the importance of application and designing of gaskets with the main focus on cylinder head gasket which plays a very important role in engine performance. The gaskets are classified as cylinder head gasket, exhaust line gasket, intake line gaskets, and sump gaskets and cover gaskets in the order of decreasing complexity. The design philosophy of cylinder head gasket with stopper or non-stopper type for combustion gas sealing is an important decision made with the experience of the designer of the gasket and the engine. The highly non-linear load deflection characteristics is challenging. The cylinder head lift during the combustion stroke is carefully studied to avoid the potential failure by gas leakage, and coolant and oil leakage. The load balance must be arrived at by both finite element analysis as well as a number of experiments both at the bench as well as at the engine dynamometer. The oil and coolant holes have to be sealed with appropriate gasket pressures with single seal bead or by elastomeric element. The cylinder head gasket surface is treated for reducing friction. The design of exhaust flange and turbocharger gaskets are confounding because of large relative thermal expansion, mechanical vibration and loss of bolt tension. Design principle of rocker cover gasket and oil sump gaskets to seal oil from leakage is discussed. The formed-in-place gasket is cost effective and avoids severe loss of elasticity of the joints.
Osamu Aizawa

Chapter 17. Design of Valve Train for Heavy Duty Application

Abstract
Today’s high speed and heavy-duty engine demands precise design and analysis of the various engine components. Amongst the various components, valve train of an Internal Combustion (IC) engine plays the crucial role. The components of valve train like camshaft, tappet, pushrod, rocker arm, valves etc. are subjected to inertia and vibrational forces. The valves are also subjected to thermal loads. These forces should be studied to make sure precise and controlled functioning of the valve train. The complex task of valve train system design and development can be achieved by theoretical and simulation analysis which considers mechanical, thermal and hydrodynamic factors. Different simulation tools are available for valve train kinematic analysis. This chapter describes about the methods of cam design, valve train layouts, theoretical analysis of valve train design and comparison with simulation results, tribology of valve train and experimentation of valve train.
Aniket Basu, Nitin Gokhale, Yogesh Aghav, M. N. Kumar

Chapter 18. Engine Retarders

Abstract
One of the important reasons for higher efficiency of a diesel engine at part loads than a conventional spark ignition engine is because of the missing throttle in the inlet duct of the engine. However, for the same reason, the braking of a diesel-powered truck by the pumping power of the engine alone is insufficient and hence, the load on service brakes on the wheels is not graceful. Insufficient braking on slopes or during down-shifting of gears, causes over-speeding the engines and endangers parts under dynamic inertia forces. For example, limiting design speeds are in the increasing order: valve train, connecting rod, flywheel. For handling heavy trucks and buses, retarder is necessary. The exhaust brake invented by Clessie Cummins, named Jake brake is the first effective solution and it is still common in low tonnage vehicles, because it is cost-effective. With increased power density in terms of hp/litre capacity of modern diesel engines, an exhaust brake is not enough to retard high tonnage vehicles. In this chapter, the theory of the required braking power (hp/ton) for a given vehicle and the pumping power of a given engine (hp/litre) is derived; later, their estimation is described, Then, various systems and devices of different capacities are described for a designer to make a suitable choice.
M. V. Ganesh Prasad

Chapter 19. Engine Gear Train Design

Abstract
A drive system is generally located at the front of the engine and is used to drive essential engine components such as camshaft, fuel pump and oil pump. All gears are finally connected to the crank gear which provides the input power to all other gears. First the choice of spur or helical gear is made considering various aspects like noise, width allowed for the gear casing, machining simplicity ability to maintain accuracy and overall cost of the engine. Gear train can be simple or compound, the latter resulting more compact train. Contact ratio of engagement is studied for strength estimation as well as noise. For the complete design of engine gear train, first, loads from the fuel injection pump, engine camshaft, oil pump, water pump, air compressor and the hydraulic pump are estimated. The choice of the gear pressure angle is made considering its significance to the normal load on the shafts and the bearings. The calculation of gear consists of forces on gear, basic rack tooth, profile selection, material and heat treatment process. Then the safety factor for surface durability and tooth bending are calculated. The backlash of gear train is usually higher in engines using shell bearings than in, e.g., machinery using ball bearings, because of higher bearing clearances. While large backlash enables gear-train running free of interference, it can introduce rattle especially at those gear-pairs, where the load is alternating, e.g., at the gear driving high pressure plunger type fuel pump. Gear whine at high frequency stands out even when its sound power is relatively less than from other noise sources. The choice of gear material is made considering material availability, cost, fatigue limits, temperature limits, fracture toughness, load and torque carrying capacity, manufacturing requirements, weight, treatments, machinability, operational characteristics, damping characteristics, and corrosion and wear resistance. While designing the steel gear train, heat treatment is specified for strength against wear, pitting and bending.
Vishal Bhat, M. N. Kumar, Yogesh Aghav, Nitin Gokhale

Chapter 20. Piston and Rings for Diesel Engines

Abstract
The piston is at the heart of an engine inside the cylinder bore, forming a moving boundary of the combustion chamber. The pistons are designed to have high strength, low weight, stability at high temperature, wear and corrosion resistance and thermal conductivity apart from easiness to cast and machine. This chapter is divided into three parts: Aluminium piston, piston rings and Cast-Iron pistons. (1) Today, the most popular material is hypereutectic aluminium satisfying the needs. The properties of aluminium are enhanced by alloying with silicon, copper, nickel, zinc, lead, titanium, phosphorus, zirconium and vanadium in optimum proportion. However, the ring groove wear in diesel is solved by a cast iron ring carrier inserted in the aluminium piston. In this chapter, the typical dimensions of the piston and their proportions with respect to the nominal diameter are given to initiate the design. The classical formulae for the sizing of pistons and pins for strength are provided. A detailed study of the piston expansion and movement, rings flutter, flow of oil and gases past the piston assembly though can be made with the help of a computer using both the time-honoured calculus and importantly by using the finite element method. The phenomena are explained using several examples. Pistons are manufactured by forging or casting process depending upon the strength, weight and cost. The casting process results in major or minor defects. Under major, air entrapment at ring zone, sludge at ring zone, eddy current rejections, ring insert variation, cooling gallery tilt, cold shut, bonding mistake or corrosion could arise. Minor defects are miss-handling, air entrapment at pin bore, in-gate broken, impression of glass fibre filter, etc. Systematic analysis of rejections due to defects can be carried out by creating a cause and effect diagram and actions to control or improve the process are taken. An example is provided. (2) Rings are proportioned similar to the pistons. They are made of cast iron mostly and when strength demands either nodular cast iron or steel is used. With higher strength materials, the additional advantage is the ability to design narrow faces to scrape oil better at the same maintain lower tangential load of the rings which helps in reducing the friction power and hence fuel consumption. The formulae useful for the layout of rings is given. (3) In some new generation engines, with the increasing cylinder pressure in the downsized engines to achieve higher power to weight ratio or in engines with high EGR, aluminium is not able to contain the creep and is replaced by forged steel. The highly loaded steel pistons are invariably gallery cooled by oil. The gallery is created by either laser welding the top crown or by friction welding. One to one replacement of aluminium to forged steel would bring in unbearable penalty of weight; however, clever use of the strength of steel as well its conductivity enabled radically new shape of pistons that have relatively lower compression height as well as weight equal to an aluminium piston. The simulation and calculation of the steel piston remains the same as that for aluminium piston but for the change in properties of the material.
Subrata Neogy, Vikas Ramchandra Umbare, Vineet Ahluwalia, P. A. Lakshminarayanan

Chapter 21. Cooling, Coolants, and Water Pump and Oil Pump

Abstract
In a diesel engine the parts in contact with the high temperature gases like piston, liner and cylinder head are kept within safe temperature limits by a coolant constantly circulated over the surfaces. The heat to be transferred to the coolant is estimated for EGR, non EGR and CNG engines. When the heat transfer fails, the oil becomes too thin to support the piston rings, valve seats and the valve stems and seizure takes place. Chemicals are added to demineralised water maintain the surfaces corrosion free and help in hardness salts remain suspended without forming solids to block the intricate passages. The coolant is maintained at a higher pressure by a cap on the radiator to enable higher boiling point; the freezing point can be lowered by adding ethylene glycol in eutectic proportions which also increases the boiling point. Addition of highly corrosive alcohol brings in additional responsibilities to the additive package, especially to protect the radiators and engine parts made of aluminium.
S. Seetharaman, P. A. Lakshminarayanan

Chapter 22. Design of Electronic Control for Diesel Engines

Abstract
The main drivers of engine development are fuel economy and very high emission standards that need tighter control of fuel injection during the highly transient automotive cycle. For long, the responsibility is surrogated by mechanical controllers to high speed digital controls that are electronic. The intimate control of injection pressure injection timing, rate of injection and most importantly the number of injection pulses per cycle are controlled by the ECU, not only for limiting the engine-out emissions or reducing fuel consumption, but also for control of noise and after-treatment system. This chapter gives an overview of common rail injection system and working of the electronic injector, listing their advantages. The features of electronic control unit (ECU) are air charge management, torque set-point function, torque limitation function, engine speed control, engine position management, metering unit control and pressure relief valve control as well as fault diagnostics and on-board diagnostics are discussed. The engine management system has inputs, outputs, sensors and actuators apart from sensors and the pedal module. In the latest on-board diagnostic requirements, there is a need for monitoring rationality of sensor signals and total functional failure are important for detecting total breakdown of the system (such as loss of after-treatment device, EGR cooler or charge air cooler) or a component, or loss of a component like the catalyst. Inducement strategies of low level, maximum vehicle speed and OBD disablement, and electronic control of after-treatment system and EGR as well as OBD I and OBD II needs are treated at the end of the chapter. The topics on development process of an ECU, hardware-in-loop, software-in-loop, verification on vehicle for series production, production code generation and closed loop control mechanism are briefly dealt with.
M. Leelakumar

Noise and Vibration

Frontmatter

Chapter 23. Study of Noise and Vibration Problems Related to Heavy Duty Diesel Engines

Abstract
Noise can be described as what is heard, and vibration as what is felt by a person. The pulsation of air particles in contact with vibrating structure or fluctuating flow causes noise. Noise from the engine due to exhaust and inlet flows are predominant at lower frequencies and at high frequencies it is usually structure related. Noise from the cooling fan is not negligible. Noise at steady state is studied but more annoying is transient noise. The pass-by and interior noise are the net effect of the noise from the engine, tires, vehicle panels, the fan and the exhaust silencer. Exhaust noise and engine noise are the loudest components of the pass-by noise from diesel trucks and buses. Vibration on the other hand, is mainly due to inertia forces left unbalanced by design as well as inevitable manufacturing tolerances to the masses and linear dimensions. Further, the side thrust to the cylinder walls and the forces at the bearings induce a vibrating torque about the crankshaft axis, proportional to the brake mean effective pressure. This chapter is written under three subtitles namely, noise at steady state, transient noise and engine vibrations.
P. A. Lakshminarayanan

Future

Frontmatter

Chapter 24. Future Diesel Engines

Abstract
This chapter provides a survey of technology trends expected in future diesel engines. Although diesel engines have dramatically changed over the years, the basic qualities that initially made these engines desirable remain the same: fuel economy, performance, reliability, and durability. Performance, reliability, and durability have seen big advances, but perhaps one of the largest changes in the modern diesel engines is the addition of sociability as a key driver and the introduction of diesel exhaust aftertreatment as a result. Requirements on fuel efficiency and emissions are motivated by global economic and environmental implications of the use of fossil fuels. These technology-forcing-factors are expected to play crucial roles in developing future engines as well. Irrespective of the geographic region, engine manufacturers will have to seek an integrated perspective and significant advancements in the fuel quality and subsystems dealing with air handling, fuel systems, combustion, controls and exhaust aftertreatment are expected. There is an increasing trend to move towards cleaner combustion strategies that can significantly reduce the levels of emissions within the cylinder itself by operating in non-traditional diesel engine operating regimes or by controlling fuel composition. The quest for alternative energy sources for diesel engines is expected to continue for reasons of energy independence, emissions reduction, fuel efficiency and GHG reduction. Use of natural gas and biofuels produced from indigenous options are being actively pursued. Hybridization of diesel is in early stages and is continued to be a key enabler for GHG and emissions reduction, as well as fuel efficiency. High pressure common rail injection with precise control of number of pulses and duration, and flexible control of injection rate shaping are being developed, and it is expected that optimization of nozzle design and ECU control strategies will complement these developments. Challenges lie in ensuring fuel quality and in sensors and control systems development. High efficiency aftertreatment systems that integrate oxidation catalysts, wall-flow DPFs, de-NOx catalysts, HC and DEF injectors as well as sensors and closed loop controls are being pursued. Devices with combined functionalities (such as SCR-F) are particularly interesting. For today’s engines, aftertreatment integration and optimization is as critical and complex as turbocharger mapping and fuel injector tuning. The development of intake charge filtration systems will be motivated by need to improve filtration capacity, efficiency and pressure drop reduction. Use of Organic Rankine cycle and electric turbo-compounding are promising for waste energy recovery. Though turbocharger and EGR technologies have reached relative maturity, their optimum integration will be crucial in view of incorporation of advanced combustion, after-treatment and waste heat recovery technologies.
Z. Gerald Liu, Achuth Munnannur
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