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Technical Paper

Simulating Real World Driving: A Case study on New Delhi

In the Indian Context, Fuel Economy of a vehicle is one of key elements while buying a Car. The fuel economy declared by OEMs (Original Equipment Manufacturers) is one of the key indicators while assessing the fuel economy. However it is based on a standard driving cycle and evaluated under standard conditions as mandated by emission legislation. As the driving pattern has a major influence on fuel economy, the objective of this paper is to study real world driving patterns and to define a methodology to simulate a real world driving cycle. A case study was done on Delhi City, by running a fleet of vehicles in different traffic conditions. Thereafter data analysis like acceleration %, specific energy demand per distance, Acceleration vs. Vehicle Speed distribution etc. was done with the help of MATLAB. The final validation of cycle was done by comparing Lab results with on-road Fuel Economy data.
Technical Paper

Vehicle Cold Start Mode Fuel Economy Simulation Model Making Methodology

The air pollution and global warming has become a major problem to the society. To counter this worldwide emission norms have become more stringent in recent times and shall continue to get further stringent in the next decade. From OEMs perspective with increased complexity, it has become a necessity to use simulation methods along with model based systems approach to deal with system level complexities and reduce model development time and cost to deal with the various regulatory requirements and customer needs. The simulation models must have good correlation with the actual test results and at the same time should be less complex, fast, and integrable with other vehicle function modelling. As the vehicle fuel economy is declared in cold start condition, the fuel economy simulation model of vehicle in cold start condition is required. The present paper describes a methodology to simulate the cold start fuel economy.
Technical Paper

Aerodynamic Design Optimization in Rear End of a Hatchback Passenger Vehicle

Aerodynamic evaluation plays an important role in the new vehicle development process to meet the ever increasing demand of Fuel Economy (FE), superior aero acoustics and thermal performance. Computational Fluid Dynamics (CFD) is extensively used to evaluate the performance of the vehicle at early design stage to overcome cost of proto-parts, late design changes and for time line adherence. CFD is extensively used to optimize the vehicle’s shape, profiles and design features starting from the concept stage to improve the vehicle’s aerodynamic performance. Since the shape of the vehicle determines the flow behavior around it, the performance is different for hatchback, notchback and SUV type of vehicles. In a hatchback vehicle, the roof line is abruptly truncated at the end, which causes flow separation and increase in drag.
Technical Paper

Evaluation of Sound Radiation from Exhaust Muffler Shell-A Novel Experimental Approach

Shorter product development cycles, densely packed engine compartments and intensified noise legislation has increased the need for accurate predictions of passenger cars Exhaust system noise at early design stages. The urgent focus on the increasing CO2 emissions and the efficiency of IC-engines as well as upcoming technologies might adversely affect the noise emission from an exhaust system, so it is becoming increasingly important to evaluate the sub system level noise emissions in an early design stage in order to predict and optimize the exhaust system performance. Engine performance and vehicle NVH characteristics are two important parameters on which the design of the exhaust system has major influence. The reduction of exhaust noise is a very important factor in controlling the exterior and interior noise levels of vehicles, particularly to reach future target values of the pass-by noise and sound engineering for the vehicle.
Technical Paper

Fuel Efficient Algorithm for Climate Control in Next Generation Vehicles

Automobile industry is shifting its focus from conventional fuel vehicles to NexGen vehicles. The NexGen vehicles have electrical components to propel the vehicle apart from mechanical system. These vehicles have a goal of achieving better fuel efficiency along with reduced emissions making it customer as well as environment friendly. Idle start-stop is a key feature of NexGen vehicles, where, the Engine ECU switches to engine stop mode while idling to cut the fuel consumption and increase fuel efficiency. Engine restarts when there is an input from driver to run the vehicle. There is always a clash between the Engine ECU and automatic climate control unit (Auto-AC) either to enter idle stop mode for better fuel efficiency or inhibit idle stop mode to keep the compressor running for driver comfort. This clash can be resolved in two ways: 1 Hardware change and, 2 Software change Hardware change leads to increase in cost, validation effort and time.
Technical Paper

Aerodynamic Development of Maruti Suzuki Vitara Brezza using CFD Simulations

Recent automotive trend shows that customer demand is moving towards bigger size vehicle with more comfort, space, safety, feature and technology. Global market of SUV is projected to surpass 21 million units by 2020. Despite economic slowdown and weak new car sales worldwide, India and China will continue to be primary market for SUV due to sheer size of population, urban expanding middle class and larger untapped rural market. However, stricter emission norms push for clean and green technology and unfavorable policy towards use of diesel vehicle has made the SUV design very challenging due to conflicting needs. Due to bigger size of vehicle, aerodynamic design plays an important role in achieving emission targets and higher fuel efficiency. This paper highlights the aerodynamic development of Maruti Suzuki Vitara Brezza, which is an entry level SUV vehicle with high ground clearance of 198 mm and best in class fuel economy of 24.3 kmpl.
Technical Paper

Thermal Radiation Heat Transfer Model and Its Application for Automobile Exhaust Components

Shielding vehicle underbody or engine room components from exhaust heat is becoming a difficult task with increasing packaging constraints, which lead to the proximity of components with high temperatures of the exhaust systems. Heat insulators are provided to protect various components from exhaust system parts. Generally the requirement of heat insulators are fixed on the basis of benchmarked temperatures measured on vehicles with similar layout, during the initial phase of vehicle design. Also various CFD techniques are available to predict the surface temperatures on components in order to determine the necessity of a heat insulator. The aforementioned techniques use radiation and convection heat transfer effects on a complete vehicle model and the overall process generally takes considerable time to provide the results. This paper deals with a theoretical approach to predict the temperatures on nearby components due to exhaust system heat.
Technical Paper

Hybrid Controls Comparison on HILs Using a Modular Soft Platform

Hybrid Electric Vehicle (HEV) Controls Development is an important aspect to realize the goals of Powertrain Electrification i.e. fuel economy and emission improvement. Keeping that in mind, development engineers need to formulate numerous control strategies. Once the control strategy is evaluated and frozen, it typically does not change from one vehicle model application to another. However, it may happen that Electronic Control Unit (ECU) manufacturer may change depending on the sourcing strategy. Therefore, in order to maintain uniformity, it may be required to compare control strategy of a finished ECU product frozen for one model application to be compared with new ECU sourced through another manufacturer. This paper discusses a methodology to compare control strategy of two ECU’s sourced from different ECU manufacturers with identical control requirements.
Technical Paper

Development of Test Method to Validate Synchronizer Ring Design for Torsional Fluctuations in Manual Transmission

Manual transmissions dominate the Indian market for their obvious benefit of low cost and higher mechanical efficiency resulting in higher fuel economy. Synchronizer system in manual transmission enables smoother and quieter gear shifting. Synchronizer ring is the key element which provides the necessary frictional torque to synchronize the speed of gear and sleeve for smooth shifting. During vehicle running, synchronizer rings are free to rattle inside the indexing clearance. High engine torsional excitation and low clutch dampening can result into increased fluctuation of the input shaft of transmission. High fluctuation or lower contact area of synchronizer ring can lead to damage on the index area. This damage may cause hard gear shifting and gear shift blockage in case of extreme damage.
Technical Paper

Effect of Compression and Air Fuel Ratio on the Flame Kernel Development

Cycle to cycle variations is always a cause for concern in port injected SI engines. Earlier studies in this field suggest that cycle by cycle variations in the position and growth rate of flame kernel has a significant role in the cycle by cycle variations in the pressure curves. Researchers are always interested in understanding the fluid flow and combustion characteristics in a running engine to study these variations in detail. Due to its simplicity in adaptation, fiber optic spark plug enables the researchers to study the effects of charge motion on the developing flame kernel at relatively less cost and effort. In this paper 8 channel fiber optic spark plug was used to measure and understand the flame kernel development. Flush mounted pressure transducer is also installed to measure in cylinder pressure data.
Technical Paper

Challenges in Developing Low Rolling Resistance Tyre

Vehicles in India will soon come with star ratings, signifying how environment-friendly they are. The OEM's have braced to improve fuel economy of their existing & upcoming models. Tyre rolling resistance is one of the significant factors for vehicle fuel consumption. Improvement in Fuel consumption is always a prime focus area & to improve it all major factors are considered. In newly launched models, the low rolling resistance tyre development was initiated. The project is challenging as it requires not only achieving low rolling resistance in smaller size tyres (12″ to 13″) but also required to meet other critical vehicle performance parameters like ride, handling, NVH & durability. Effects of Tyre construction, rubber compound were analyzed to achieve lower rolling resistance and better durability of tyre. In addition, the factors affecting the rolling resistance of tyre like inflation pressure, load, and speed in smaller tyre sizes (12″ to 13″) are discussed in this paper.
Journal Article

Improving STL Performance of Automotive Carpets with Multi-layering and Effective Decoupling

Automotive floor carpet serves the purpose of insulating airborne noises like road-tire noise, transmission noise, fuel pump noise etc. Most commonly used automotive floor carpet structure is- molded sound barrier (PE, vinyl etc.) decoupled from the floor pan with an absorber such as felt. With increasing customer expectations and fuel efficiency requirements, the NVH requirements are increasing as well. The only possible way of increasing acoustic performance (Specifically, Sound Transmission Loss, STL) in the mentioned carpet structure is to increase the barrier material. This solution, however, comes at a great weight penalty. Theoretically, increasing the number of decoupled barrier layers greatly enhances the STL performance of an acoustic packaging for same weight. In practice, however, this solution presents problems like- ineffectiveness at lower frequencies, sudden dip in performance at modal frequencies.
Technical Paper

Design Considerations for Plastic Fuel Rail and Its Benefits

Global automobile market is very sensitive to vehicle fuel economy. Gross vehicle weight has substantial effects on FE. Hence, for designers it becomes utmost important to work on the weight reduction ideas up to single component level. Fuel delivery pipe (Fuel Rail) is one such component where there is a big potential. Fuel rail is an integral part of the vehicle fuel system and is mounted on the engine. Primarily it serves as a channel of fuel supply from fuel tank through fuel lines to the multiple fuel injectors, which further sprays the fuel into intake ports at high pressure. Due to opening and closing of injectors, pulsations are generated in fuel lines, so fuel rail also acts as a surge tank as well as a pulsation damper. All these factors make the design of a fuel rail very critical and unique for a particular engine. Materials like aluminum, plastic and sheet metal are generally used for fuel rail manufacturing.
Technical Paper

Valve Opening and Closing Event Finalization for Cost Effective Valve Train of Gasoline Engine

With more stringent emission norm coming in future, add more pressure on IC engine to improve fuel efficiency for survival in next few decades. In gasoline SI (spark ignition) engine, valve events have major influence on fuel economy, performance and exhaust emissions. Optimization of valve event demands for extensive simulation and testing to achieve balance between conflicting requirement of low end torque, maximum power output, part load fuel consumption and emission performance. Balance between these requirements will become more critical when designing low cost valve train without VVT (Variable valve timing) to reduce overall cost of engine. Higher CR (Compression ratio) is an important low cost measure to achieve higher thermal efficiency but creates issue of knocking thereby limiting low speed high load performance. The effective CR reduction by means of late intake valve closing (LIVC) is one way to achieve higher expansion ratio while keeping high geometric CR.
Technical Paper

Evaluating the Effect of Light Weighting Through Roll Stiffness Change on Vehicle Maneuverability and Stability

Objective To achieve better fuel economy and reduced carbon footprint, OEMs are reducing the sprung and unsprung mass. This translates into a reduction in stiffness which profoundly deteriorates the handling/road holding characteristics of the vehicle. To model these changes in stiffness, modifications are made to suspension roll stiffness at the front and rear. This study compares different configurations of roll stiffness and evaluates vehicle behavior using frequency response characteristics and phase change of Yaw Gain recorded. The present work associates acquired data with subjective feedback to outline the shift in vehicle balance emerging from a variation of sprung and unsprung mass ratio. Methodology To study the frequency response characteristics of the vehicle, the pulse input is chosen for this. An ideal pulse input’s Fourier transform represents constant amplitude over all the frequency ranges. By giving a single input, the system is subjected to a range of frequencies.