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With the current state of ever rising fuel prices and unavailability of affordable alternate technologies, significant research and development efforts have been invested in recent times towards improving fuel efficiency of vehicles powered with conventional internal combustion engines. To achieve this, a varied approach has been adopted by researchers to cover the entire energy chain including fuel quality, combustion quality, power generation efficiency, down-sizing, power consumption efficiency, etc. Apart from energy generation, distribution and consumption, another domain that has been subjected to significant scrutiny is energy recuperation or recovery. A moving vehicle and a running engine provide a number of opportunities for useful back-recovery and storage of energy. The most significant sources for recuperation are the kinetic energy of the moving vehicle or running engine and to a lesser extent the thermal energy from medium such as exhaust gas.

With India achieving the BSVI milestone, the diesel particulate filter (DPF) has become an imperative component of a modern diesel engine. A DPF system is a device designed to trap soot from exhaust gas of the diesel engine and demands periodic regeneration events to oxidize the accumulated soot particles. The regeneration event is triggered either based on the soot mass limit of the filter or the delta pressure across it. For a Heavy Duty Diesel Engine (HDDE), pressure difference across the DPF is not usually reliable as the size of the DPF is large enough compared to the DPF used ina passenger vehicle diesel engine. Also, the pressure difference across DPF is a function of exhaust mass flow and thus it makes it difficult to make an accurate call for active regeneration. This demands for a very accurate soot estimation model and it plays a vital role in a successful regeneration event.

Optimization of vehicle engine cooling package with requisite heat rejection capacity plays a key role in achieving most fuel economy and also in meeting the stringent noise norms. A set of design and operating features from existing vehicle engine cooling systems is reviewed and evaluated for their potential to provide optimized engine cooling. The features reviewed states significant potential in engine performance but these are balanced by satisfying required engine cooling requirement. Sets of trials are carried out on said vehicle with dissimilar features of cooling packages and the results are evaluated. Fuel economy trials in performance mode are carried out on vehicle with well thought-out cooling package for healthier comparison.

For an automotive exhaust system, noise level and back pressure are the most important parameters for passenger comfort and engine performance respectively. The sound quality perception of the existing silencer design was unacceptable, although the back pressure measured was below the target limit. To improve the existing design, few concepts were prepared by changing the internal elements of silencer only. The design constraints were the silencer shell dimensions, volume of silencer, inlet pipe and outlet tailpipe positions, which had to be kept same as that of the existing base design. The sound quality signal replaying and synthesizing was performed to define the desired sound quality. The numerical simulation involves 3D computational fluid dynamics (CFD) with appropriate boundary condition having less numerical diffusions to predict the back pressure. The various silencer concepts developed with this preliminary analysis, was then experimentally verified with the numerical data.

Important vehicle performance parameters such as, fuel economy and high speed stability are directly influenced by its aerodynamic drag and lift. Wind tunnel testing to asses these parameters requires heavy investment especially when test wind tunnel is not available in the country where vehicle development center is present. Hence to save cost and to compress development time, it is essential to asses and optimize parameters of a vehicle in very early stages of development. Using numerical flow simulations optimization runs can be carried out digitally. Industry demands prediction of aerodynamic drag and lift coefficients (CD,CL) within an accuracy of a few counts, consuming minimal HPC resources and in a short turnaround time. Different OEMs deploy different testing methods and different softwares for numerical simulations.

Liquefied Petroleum Gas (LPG)-powered vehicles use a pressure regulator/vaporizer to expand and modulate the gas pressure to meet the engine's operational demands. This expansion process is accompanied by a phase change wherein liquid LPG is converted to its gaseous form. This consequently reduces the temperature of the working fluid which may result in freezing (Joule-Thompson effect). In order to aid complete phase change and avoid any freezing, the vaporizer is heated either electrically or by the engine coolant circulation. Any inefficiency in the heating may lead to improper phase change and can result in a phenomenon known as "liquid carryover," wherein a liquid LPG gets entrained in the downstream gas circuit where the gaseous form is demanded. The liquid carryover (if any) leads to the improper engine functioning leading to driveability and emission issues.

Diesel engines tend to operate on lower exhaust temperatures, compared to their gasoline counterparts. Exhaust emission control becomes a significant issue at these lower temperatures, as any catalytic converter needs certain light off temperature to commence functioning. The trend so far has been to move the catalytic converters closer to the exhaust manifold, in order to get the benefit of higher temperatures - but most of the applications are limited to the location available after the turbo chargers. This is due the fact that very minute and efficient catalyst is required, if it has to be placed before the turbo charger. This catalyst also needs to be extremely durable to take care of high exotherms which occur within the catalysts and also to prevent any possible damage to the turbo chargers.

Regenerative braking has become one of the major features for a hybrid vehicle as it converts brake energy into electrical energy storable into battery and leads to an increase in overall fuel efficiency of the vehicle. Traditional regenerative braking systems are designed such that the mechanical braking force from the friction brakes is varied in order to get maximum electric braking. This is the optimum method; however, such a system calls from electronics (Anti-lock Braking System) for regulation of mechanical braking leading to an increased cost. In this paper, the authors present a new strategy for implementing a regenerative brake strategy without changing the mechanical brake system of a conventional vehicle converted to a hybrid vehicle. The electric motor that serves as the traction motor or the Integrated Starter Generator (ISG) system, is used for regenerative braking also. There is no change in the other vehicle specifications as compared to the conventional vehicle.

1 With increasing fuel price, the power train size is on a downward trend. For Fuel Economy maximization, the engine capacity and reduction ratios are getting reduced. So gradability of a vehicle is becoming a trade off factor for the power train size finalization in a car. At the same time OEMs are working hard to maintain profitability by reducing development and operational cost and time. In this complexly competitive scenario in automobile manufacturing, simulation is gaining an upper hand over actual testing as simulation consumes lesser time and resource as compared to actual testing. This paper is aimed at developing a simulation technique for restart or stop and start gradability which is a very critical parameter for finalization of engine torque characteristics and power train configuration. The simulation is done on AVL-CRUISE software.

Micro Hybrid Systems are a premier approach for improving fuel efficiency and reducing emissions, by improving the efficiency of electrical energy generation, storage, distribution and consumption, yet with lower costs associated with development and implementation. However, significant efforts are required while implementing micro hybrid systems, arising out of components like Intelligent Battery Sensor (IBS). IBS provides battery measurements and battery status, and in addition mission critical diagnostic data on a communication line to micro hybrid controller. However, this set of data from IBS is not available instantly after its initialization, as it enters into a lengthy learning phase, where it learns the battery parameters, before it gives the required data on the communication line. This learning period spans from 3 to 8 hours, until the IBS is fully functional and is capable of supporting the system functionalities.

Engine Stop/Start System (ESS) promises to reduce greenhouse emissions and improve fuel economy of vehicles. Previous work of the Authors was concentrated on bridging the gap of improvement in fuel economy promised by ESS under standard laboratory conditions and actual driving conditions. Findings from the practical studies lead to a conclusion that ESS is not so popular among the customers, due to the complexities of the system operation and poor integration of the system design with the driver behavior. In addition, due to various functional safety requirements, and traffic conditions, actual benefits of ESS are reduced. A modified control algorithm was proposed and proven for the local driving conditions in India. The ways in which a given driver behaves on the controls of the vehicles like Clutch and Brake Pedals, Gear Shift Lever were not uniform across the demography of study and varied significantly.

The paper describes a first-of-its-kind attempt of authors to develop an intake manifold - combined with - rocker cover (IMCRC) in sheet molding compound (SMC) for 3 L and 4 L direct injection diesel engines with power ratings 75 kW and 92 kW respectively. The objective was to reduce overall engine weight, noise and cost. The intake manifold is designed to withstand absolute boost pressures of more than 2 bar, temperature in the range of 160 °C. and capable of carrying load of directly attached components such as an air intake pipe. It is worth to note that the designed SMC component always remains in the vicinity of the exhaust manifold by virtue of base engine layout constraint. The development if successful can expand the horizon of SMC in diesel engine application.

The automotive industry is heading in the direction of signing off the exhaust system durability based on computer simulation rather than rig simulation and physical vehicle testing. This is due to the cost, time and availability of prototype vehicles and test track. Use of Finite Element Method (FEM) enables to assure the structural integrity of the exhaust system and also contribute to better understanding of the system behavior in the various operating conditions and evaluation of structural strength. This paper deals with dynamic analysis of a modular automotive exhaust system where it is directly mounted on power train pack. Selection of dynamic loads, processing of the test data, and effect of assembly loads along with material property variation due to temperature are explained. It also includes validation of the CAE model, prediction of probable failure locations and improving the design based on analysis outcome.

Primarily, Acoustic performance of muffler are evaluated by insertion loss (IL) and backpressure/restriction. Where Insertion loss is mainly depends upon proper selection of muffler volume, which is proportional to Engine Swept volume, along with internal design configuration, which drives the acoustic principle. Same time, meeting the vehicle level pass by noise (PBN) value as per regulatory norms and system level backpressure as per engine specification sheet are the key evaluating criteria of any good exhaust system. Here, a new Reactive/Reflective type muffler of tiny size have been designed for heavy commercial vehicle application, which is unique in shape and innovative to meet desire performance. In this design, mainly sudden expansion, sudden contraction, flow through perforation and bell-mouth flow phenomenon are used.

Gasoline engines with Multi point fuel injection (MPFI) technology are being developed with naturally aspirated and/or turbocharged engines. Wherein a MPFI and turbo charged combination engines have certain challenges during development stages. One of the important challenge is design of air intake and exhaust system. With MPFI turbocharged engine combination, the under bonnet heat management is crucial task for drivability. The heat management of air intake plays a vital role in drivability part therefore a design layout of air intake path is an important aspect. Drivability can be categorized as low end, mid-range and top end drivability. Turbocharged MPFI engines have a typical phenomenon of ‘Lag in response’ in the low-end region. This ‘Lag in response’ phenomenon at low-end drivability region can be overcome through optimization of air intake system and optimization of exhaust back pressure.

Authors were challenged with a task of developing a full vehicle simulation model, with a target to simulate the electrical system performance and perform digital tests like Battery Charge Balance, in addition to the fuel efficiency estimation. A vehicle is a complicated problem or domain to model, due to the complexities of subsystems. Even more difficult task is to have a control algorithm which controls the vehicle model with the required control signals to follow the test specification. Particularly, simulating the control of a vehicle with a manual transmission is complicated due to many associated control signals (Throttle, Brake and Clutch) and interruptions like gear changes. In this paper, the development of a full vehicle model aimed at the assessment of electrical system performance of the vehicle is discussed in brief.

This paper focuses on factors that enhance energy efficiency of air conditioning system on mid-sized, standard and premium buses with engine power from 125 to 280 HP. It covers aspects like light weighting of roof air conditioning system, usage of optimized ducting system with minimal resistance to blowers, deployment of rotary scroll compressor with fast idle control in place of reciprocating piston compressor. The scope of this paper covers AC compressors driven by main engine of vehicle/ bus, study related to auxiliary/donkey engine driven AC compressor is not considered. Context- In order to enhance fuel efficiency in buses an energy efficient air conditioning system should be deployed. This will lead to reduced parasitic load on the engine and translate into direct fuel saving.

A hybrid electric powertrain being a complex system requires analysis of all its subsystems to optimally utilize, size components for performance evaluation and control strategy development. An integrated high fidelity model of these can lower development costs, time and achieve the targeted performance while allowing for early redefinition of the system. A high fidelity model of a sedan car featuring chassis with longitudinal and lateral dynamics, suspension with joints, tires calculating longitudinal & lateral forces during vehicle motion, Engine model with combustion & dynamics of reciprocating and rotating components, Electric motors, Battery system, and gearbox with synchronizers and friction components was developed. Powertrain components were interconnected using 3D rotational flanges. Weight distribution was accomplished by appropriately locating various powertrain components using 3D supporting mounts, which help to study the mount forces as well.

Better ride and comfort, enhanced safety, reliability and durability, lower running cost as well as cost of ownership continue to be challenges for automotive OEMs. Higher fuel efficiency is considered as USP not only for lower running cost but also is hygiene factor from sustainability point of view. This has necessitated the need for Augmenting Light weighting horizon in automotive OEMs. Augmenting this leads to invention of innovative materials and processes for emerging cost competitive market. This paper focuses on technology efforts towards augmenting light weighting Horizon in Automotive. Light weighting concepts being explored by OEMs with the help of automotive component manufacturers from Powertrain - Engines & Transmission, Chassis and Suspension are discussed.

In a heavy commercial vehicle, the engine cooling package is designed by considering peak heat load on the vehicle cooling system from an engine end. In cooling systems, the major unit that consumes most power from the engine is the engine cooling fan. It was seen from the vehicle measured duty cycle data, for most of the time engine operates at part load condition. Regardless of demand from the engine cooling system, engine fan was operating continuously at equivalent speed of the engine. This results in continuous consumption of productive engine power from the fan end ultimately affecting vehicle fuel economy. The present study shows that low idle speed viscous fan has the potential to meet stringent engine cooling performance requirements and consumes less engine power throughout an actual vehicle duty cycle. Experiments were conducted on test vehicle with different fan speeds.