Over the past several decades, the automotive industry is more focused on reducing engine, wind, and road noise to improve comfort. However, as background noise levels continue to decrease, the squeaks and rattles created by the many components inside and outside the vehicle become gradually noticeable, and annoying. In electric vehicles the squeaks and rattles noise becomes more dominant than other type of noise as a result of absence of dominant noise source of engine from conventional petrol/diesel vehicle. In this paper, we are proposing a simulation methodology to develop a systematic approach to identify and solve squeak and rattle problems in vehicle components/sub-assemblies at primary stage of product development. This work will present a unique approach in understanding varied methods and Design of Experiments (DOE) techniques used to identify root-cause of squeak and rattle problems and to find a solution by using numerical methods.
In order to meet the challenges of future CAFE regulations & pollutant emission, vehicle fuel efficiency must be improved upon without compromising vehicle performance. Optimization of engine breathing & its impact on vehicle level fuel economy, performance needs balance between conflicting requirements of vehicle Fuel Economy, performance & drivability. In this study a Port Fuel Injection, naturally aspirated small passenger car gasoline engine was selected which was being used in a typical small passenger car. Simulation approach was used to investigate vehicle fuel economy and performance, where-in 1D CFD Engine model was used to investigate and optimize Valve train events (Intake and exhaust valve open and close timings) for best fuel economy. Engine Simulation software is physics based and uses a phenomenological approach 0-D turbulent combustion model to calculate engine performance parameters. Engine simulation model was calibrated within 95% accuracy of test data.
From April 2020 BS 6 phase 1 legislation has come into place in India. Further in the coming years from 2022 CAFÉ norms will be implemented targeting 122 g/km CO2 fleet emissions. Also from year 2023 onwards BS 6 phase 2 emission legislation with RDE cycle will be in place. With the expensive exhaust after-treatment system needed for meeting BS 6 norms, the Diesel powertrain based vehicles cost has increased further creating even further price difference to it's Gasoline fuel variants. Additionally the price difference between Diesel and Gasoline fuel is always reducing. These reasons have changed the buying pattern of passenger cars in India, with vehicle powered by engine<1.5 L displacements have gradually shifted predominantly to Gasoline powertrain. The impact of this will further stress the fleet CO2 emissions for manufacturers.
One of the main objective of manufacturer is to achieve high productivity with low cost while increasing the customer satisfaction. With increased competition in the automotive sector the product quality is defined not only from fuel economy and durability perspective but also Noise, Vibration and Harshness (NVH), which plays a vital role in attracting the customers. In two wheeler, engine is dominant noise source and its quality improvement is utmost priority. Now a days, several signal processing and sensing techniques are developed for noise source identification of an engine but precise source identification can be achieved only by advanced analysis technique. This paper focuses on a procedure for noise source identification from engine sub-system viz. valve operation and its generation mechanism using crank angle domain analysis in two wheeler engine. Baseline noise measurements were carried out for critical frequency identification.
Today’s automotive industry is changing rapidly towards environmentally friendly vehicle propulsion systems. All over the globe, legislative CO2 consumption targets are under discussion and partly already in force. Hybrid powertrain configurations are capable to lower fuel consumption and limit pollutant emissions compared to pure IC-Engine driven powertrains. Depending on boundary conditions a numerous of different hybrid topologies- and its control strategies are thinkable. Typical approach is to find the optimum hybrid layout and strategy, by performing certain technical design tasks in office simulation directly followed by vehicle prototype tests on the chassis dyno and road. This leads to a high number of prototype vehicles, overload on chassis dynos, time consuming road test and finally to tremendous costs. Our new developed approach is using the engine testbed with simulation capabilities as bridging element between office and vehicle development environment.
Vehicles consume energy and release harmful emissions throughout their life period from the manufacturing stage of raw materials to the vehicle scrapyard. Current Green-House Gas (GHG) emissions with gasoline and diesel vehicles are reported to be 164 gCO2/km and 156 gCO2/km respectively. Thus, enormous researches are carried out for low-carbon alternatives replacing conventional gasoline and diesel vehicles to reduce GHG emissions. The continuous research on hydrogen as a transportation fuel has demonstrated the potential of reduced vehicular emissions compared to conventional fuels. Life cycle assessment (LCA) is a comprehensive technique used to estimate the overall environmental impact of vehicles. In this present work, a comparative LCA is conducted between Compressed Natural gas (CNG) powered vehicles and H-CNG powered vehicles. Also sustainable indicators such as Net Energy Ratio, Fossil Energy Ratio are evaluated for the test cases.
Gearbox power transfer efficiency is a major factor in overall powertrain efficiency of a car. 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 gearbox 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.
Due to ever increasing demand of more fuel efficient engine with lower manufacturing cost, compact design and lower maintenance cost; OEM’s prefer three cylinder internal combustion engine over four cylinder engine. Though customer demands NVH characteristics of a three cylinder engines to be in line with four cylinder engine. Crank-train balancing plays most vital role in NVH aspects of three cylinder engines. A three cylinder engine crankshaft with phase angle of 120 degrees poses a challenge in balancing the crank train. In three-cylinder engines, total sum of unbalanced inertia forces occurring in each cylinder will be counterbalanced among each other. However, parts of inertia forces generated at No.1 and No. 3 cylinders will cause primary and secondary resultant moments about No. 2 cylinder. Conventional method of designing a dynamically balanced crank train is time consuming and leads to rework during manufacturing.
There has been a persistent demand for Vehicle fuel efficiency improvement, mainly due to ever-increasing fuel price and imposition of stricter regulatory norms to curb greenhouse gas emissions. Factors like driving style, vehicle weight, engine, tyre, aerodynamics, weather conditions, etc. affect fuel efficiency. This study focuses on the impact of certain sub-parameters like tyre construction, tyre wear, inflation pressure and driver behavior to establish a correlation between the Rolling Resistance Coefficient (RRC) of a tyre and the fuel efficiency of the vehicle. Tyres with contrasting RRC are considered with multiple drivers and driving conditions while measuring Fuel efficiency using test cycles defined as Constant Speed Test (CST), Mixed Cycle Test (MCT) and Public Road Test (PRT). Fuel consumption sensitivity to driving behavior or driving aggressiveness varies even within expert drivers .
Short development cycles, less packaging space and stringent noise emission rules have increased the need of CAE usage and first time right design approach. Engine exhaust noise is the main contributor of automotive noise when vehicle speed is low to moderate. Exhaust noise contains tailpipe noise and shell radiation noise. As vehicle speed increases, contribution of flow noise and tire noise is comparatively at higher side. The cold end development engineer is responsible to design a muffler to meet tailpipe and shell radiation noise targets. Muffler shell stiffness is a key characteristic for deciding shell radiation noise. High intensity pulses of exhaust gas passes through the exhaust pipe and hits cold end from inside which causes shell vibration and respectively shell noise. There are several conventional methods available to improve shell stiffness, but all of them are not applicable for ‘double layered critically shaped mufflers’ and all of them are not cost-effective.
Today the whole automotive world is progressively transforming towards the adoption of new alternate and innovative technologies evolving in ICE to meet the stringent emission regulations and future CO2 goals while protecting the environment; may it be a Electrification, Various degrees of hybridization, Alternate fuels, Engine downsizing, Cylinder deactivation or VVT etc. The key to achieve better FE, reduction in CO2 or emissions is realized by saving every pie of energy spent or reducing the parasitic losses and improving engine efficiencies wherever possible. In this paper, an experimental study on the deployment of various energy saving technologies are exploited on small 2 Cylinder CRDI BSVI engine for friction reduction moving forward from BSIV to BSVI phase. In first step, Piston-Ring pack is optimized for energy saving potentials by design and surface coating modification approach. Design optimizations are done in balancer shaft to improve energy losses.
Automotive suspension system forms the basis for the design of vehicle with durability, reliability and NVH requirements. The automotive suspension systems are exposed to dynamic and static loads which in turn demands the highest integrity and performance against fatigue based metallic degradation. The current focus in automotive industry is to reduce the weight of the automotive parts and components without compromising with its static and dynamic mechanical properties. This weight reduction imparts fuel efficiency with added advantages. High-strength low alloy steel (HSLA) offers optimum combination of mechanical properties. Furthermore, welding processes offer design flexibility to achieve robust and lightweight designs with high strength steels. However, welding process has to be established to get optimum benefits of high strength steels with minimal adverse effects and deterioration of the static and dynamic mechanical properties of the weldments.
In a Passive suspension, damping force is generated by a shock absorber by pressurizing the oil flow between chambers. Typically, vehicle responds with suspension deflection which significantly depends on damping forces and velocity. Tuning damping forces for various road and steering input is a Black box. In any setting, damping force w.r.t velocity is tuned for optimum ride and handling. Practically, to achieve a balance between the two is a tedious task as the choices & arrangements of inner parts like piston, port, valve etc., which defines the forces set up [soft / hard] are infinite. The objective of this paper is to measure, objectify and evaluate the performance of two such optimum setting in various ride and handling events. A passenger car set up with an optimum soft & hard suspension damping force, is studied for various ride and handling sub-attributes and their conflicts are examined in detail from a performance point of view.