Search Results

In the recent years world-wide automotive manufacturers are continuously working in the research of the suiTable technical solutions to meet upcoming stringent carbon dioxide (CO2) emission targets, defined by regulatory authorities across the world. Many technologies have been already developed, or are currently under study, to meet the legislated targets. To meet this objective, the generation of tumble at intake stroke and the conservation of turbulence intensity at the end of compression stroke inside the combustion chamber have a significant role in the contribution towards accelerating the burning rate, increasing the thermal efficiency and reducing the cyclic variability [1]. Tumble generation is mainly attained by intake port design, and conservation is achieved during the end of compression stroke 690 ~ 720 crank angles (CA) which is strictly affected by the piston bowl geometry and pentroof combustion chamber shape.

Vehicles which are sold and put into service in a country have to meet the regulations and standards of that country. Every country has a separate regulation and approval procedure which requires expensive design modifications, additional tests and duplicating approvals. Thus, there is the need to harmonize the different national technical requirements for vehicles and form a unique international regulation. With this rationale, the World Forum for Harmonization of Vehicle Regulations of the United Nations Economic Commission for Europe (UN/ECE/WP29) has brought governments and automobile manufacturers together to work on a new harmonized test cycle and procedure which is to be adopted around the world. This lead to the development of Worldwide Harmonized Light Duty Test Procedures (WLTP) and Cycles (WLTC). The test procedure is divided into 3 cycles, depending on a power to mass ratio of the tested vehicle.

In recent years, world-wide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent carbon dioxide (CO2) emission targets, as defined by international regulatory authorities. Many technologies have been already developed, or are currently under study, to meet legislated targets. In-line with above objective, the enhancement of turbulence intensity inside the combustion chamber has a significant importance which contributes to accelerating the burning rate, to increase the thermal efficiency and to reduce the cyclic variability [9]. Turbulence generation is mainly achieved during the intake stroke which is strictly affected by the intake port geometry, orientation and to certain extends by combustion chamber masking. Conservation of turbulence intensity till 700~720 crank angle (CA) is achieved by optimized shape of combustion chamber geometry and piston bowl shape.

In recent years, worldwide automotive manufacturers have been continuously working in the research of suitable technical solutions to meet upcoming stringent Real Driving Emission (RDE) and Corporate Average Fuel Economy (CAFÉ) targets, as set by international regulatory authorities. Many technologies have been already developed, or are currently under study by automotive manufacturer for gasoline engines, to meet legislated targets. In-line with the above objective, there are many technologies available in the market to expand lambda 1 (λ=1) region by reducing fuel enrichment at high load-high revolutions per minute (RPM) by reducing exhaust gas temperature (for catalyst protection) for RDE regulation [1]. Integrated Exhaust Manifold (IEM) is the key technology for the Internal Combustion (IC) for the subjected matter as catalyst durability protection is done by reducing exhaust gas temperatures instead of injecting excess fuel for cooling catalyst.

Fun to drive, pick-up of vehicle, high acceleration feeling of vehicle, time to reach max velocities are some parameters prevailing in the passenger vehicle market. In addition to focusing on information about fuel economy declared by manufacturer, the customer also has drivability related criteria in his mind. Although drivability is subjective, it can be judged by using various parameters like maximum speed, pick-up feeling, overtaking acceleration, time to reach 0 – 100 km/h or 0 – 60 km/h, etc. While comparing two vehicles of the same segment, one vehicle may perform better on some of the parameters while losses on others. To decide overall drive performance of a vehicle based on various measured performance related parameters, a methodology is defined. This will help to understand the overall performance of a vehicle holistically and to compare its performance with other vehicles in a better way.

With the advent of stricter regulation for tail pipe emission and urge to reduce the carbon foot prints, the engine hardware has undergone through evolutionary changes over the years i.e., boosting, low viscosity engine oil, high pressure fuel injection, cooled EGR, friction reduction, downsizing etc. These technological changes have led to the challenge of increase in radiated noise level from the engine (source) due to increased number of auxiliary drives on engine i.e., Turbo charger, HP fuel pump along with faster combustion & harsher operating conditions. The fuel system is one such system which has become most intricate with operating pressure going above 2000bar in the fuel rail and capability of up to 10 fuel injection per combustion. These changes in hardware could result in abnormal noise generation during specific operating conditions which may result in customer annoyance inside vehicle cabin.

In today’s Indian automotive industry, vehicles are becoming more complex and require more efforts to develop. Also, new and upcoming regulations demand more trials under varied driving conditions to ensuring robustness of emission control. Combined with expectations of customer to get new products more frequently, requires solutions and methods that can allow more trials with required accuracy to ensure compliance to stricter regulation and delivery a quality product. This translates into more trials in less time during the development life cycle. Recently, to overcome above challenge, there has been focus on simulating the vehicles trials in engine bench environment. ‘Road to Lab to Math’ (RLM) is a methodology to reduce the effort of On-road testing and replace it with laboratory testing and mathematical models. Also, on-road testing of prototype vehicles is expensive as it requires physical parts.

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.

Blending locally produced ethanol with petrol will help India strengthen its energy security. India is making steady progress in raising the share of ethanol having increased to 8.1% in ethanol supply year 2020-21 (Dec-Nov) with target to achieve 10% ethanol blending in the ethanol supply year 2021-22. In future, Government of India is planning to start supply of 20% ethanol blended petrol from Apr’23 and to cover PAN India by Apr’25. Pure ethanol has lower calorific value than Petrol thus ethanol blended petrol will always have calorific value lower than that of petrol thereby deteriorating Fuel economy. On the other hand, ethanol blended petrol will have higher RON compared to petrol. Higher RON reduces knocking tendency thereby providing calibration optimization potential to optimize Spark timing. Optimized spark timing can help in improving Full Load Torque by reducing Phasing losses and operating closer to MBT.

In view of global concern for greenhouse gas emissions, need for greener and efficient Engines is increasing. Hence is it imperative that Internal Combustion Engines are improved in terms of efficiency to reduce Greenhouse gas emissions and meet CAFE targets. The cooling system of an ICE plays a major role in a vehicle performance. In this system, the radiator, thermostat, and cooling fan are the main components. Conventional cooling system uses Wax-type thermostat which is activated at specified coolant temperature and maintain same coolant temperature in fully warmed up condition at all engine operating points. Operative temperature selection in Wax-type is trade-off between engine friction & thermal efficiency at lower loads & knocking at higher loads. An electronic thermostat is a good alternative to maintain optimum temperature as per operating point requirement since optimum temperature at different operating points can be different.

Exhaust system of an automobile is primarily employed in automobile to purify exhaust gases and reduce noise due to combustion. However, a side-effect of the above function is the increase in backpressure. As specified in various literatures, an increase in backpressure can lead to a deterioration on engine performance (Power & torque). Benefit of backpressure reduction can be further taken in terms improving the power & torque of engine or improving the fuel economy. With growing concerns related to global warming and CO2 emissions, reducing exhaust back pressure is one of the promising areas in engine design in order to improve the fuel economy of the automobile and achieving carbon neutrality targets. However, reducing the back pressure generally tends to deteriorate the noise attenuation performance of the Exhaust system.

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.

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.

Valve train system is one major contributor to engine overall friction loss and is approximately 30% of total engine friction at lower speed and approximately 20 % at higher engine speed. Valve spring loads (preload and working) are proportional to friction loss of valve train. To optimizing the valve spring design main requirement is valve train perform it function safely at maximum engine cutoff RPM with minimum preload and working load. Robustness and frictional power loss are contradicting requirement, robustness demand high stiffness spring for better valve jump and bounce performance with dynamic safe valve spring design, on the other hand low frictional power loss demand for use of low stiffness spring. To optimize the valve spring stiffness for meeting both the requirement we need accurate prediction of valve spring in design stage and good correlation with testing data to reduce the number of iterations.

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.

Gearbox power transfer efficiency is a major factor in overall powertrain efficiency of a passenger vehicle. With rapidly changing emission and fuel efficiency regulations, there is a push to increase the gearbox efficiency to improve the overall fuel economy of the vehicle. In case of an existing gearbox, efficiency can be improved by using the low viscosity lubrication oil. Despite a benefit in increasing the gearbox efficiency, lowering down the viscosity of lubrication oil gives rise to few challenges with respect to its performance. One of these challenges is breather performance which defines that transmission oil should not come out of breather pipe in some pre-defined conditions during gearbox operation. As this validation is being carried out on proto parts when the complete system is ready, failure to satisfy the defined criteria for breather performance can lead to multiple trials.