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Technical Paper

A Simple Mechanism for AC Compressor Operation

One of the most essential components of automotive HVAC system is compressor. In a vehicle it is directly mounted on the engine. It derives power from the engine feed system to keep refrigerant moving in the HVAC system of the vehicle. It is also essential to complete the vapor compression cycle. During the operation, it causes considerable load on the engine and thus results in lower fuel efficiency and higher pollution. There are several types of compressors available globally. According to construction it can be classified as reciprocating piston type, scroll type and rotary vane type. The reciprocating piston types of compressors are further classified as fixed displacement and variable displacement. Normally the fixed displacement compressors have good idling cooling performance, but it increases the load on the engine. To reduce the load on the engine and to have good idling cooling performance, generally a variable displacement compressor is used.
Technical Paper

Intelligent Exhaust Gas Recirculation Governing for Robust BS-III Compliant 2.5 l Mechanical Pump Drive Diesel Vehicle

October 2010 has brought major change over in Indian Auto Industries, with all India going BS-III Emission compliant (Metro with BS-IV Emission norms). During that time majority of the utility segment vehicles were having diesel engine with simple mechanical fuel injection system. To make these vehicles BS-III compliance cost effectively, with same fuel economy and reliability, was a challenging task. To enable this, Exhaust Gas Recirculation (EGR) through simple pneumatic EGR valve was the optimum technique. The EGR valve was controlled by means of simple Electronic Control Unit (ECU). Limitations of mechanical diesel fuel injection pump, stringent emission regulations, coupled with production constraints and variations, calls for robust control logics for governing EGR. The present work describes the robust strategies and logics of intelligent EGR governing of a 2.5 l, four Cylinder turbocharged, mechanical pump diesel engine for a BS-III compliant multi utility vehicle.
Journal Article

Lithium Ion Battery for Hybrid and Electric Mobility under Indian Ambient Conditions - A Perspective

Hybrid Electric Vehicles (HEVs), Plug-in Hybrid Electric Vehicles (PHEVs), Extended Range Electric Vehicles (EREVs), Battery Electric Vehicles' (BEVs) development is gaining traction across all geographies to help meet ever increasing fuel economy regulations and as a pathway to offset concerns due to climate change and improve the overall green quotient of automobiles. These technologies have primarily shifted towards Li-ion batteries for Energy Storage (due to energy density and mass). In order to make actual business sense of these technologies, of which, battery is a major cost driver, it is necessary for these batteries to provide similar performance and life expectancy across the operating and soak (storage) range of the vehicles, as well as provide the requirements at a competitive cost.
Technical Paper

Correlation of Test with CAE of Dynamic Strains on Transmission Housing for 4WD Automotive Powertrain

Reducing the vibrations in the powertrain is one of the prime necessities in today's automobiles from NVH and strength perspectives. The necessity of 4×4 powertrain is increasing for better control on normal road and off-road vehicles. This leads to bulky powertrains. The vehicle speeds are increasing, that requires engines to run at higher speeds. Also to save on material costs and improve on fuel economy there is a need for optimizing the mass of the engine/vehicle. The reduced stiffness and higher speeds lead to increased noise and vibrations. One more challenge a powertrain design engineer has to face during design of its transmission housings is the bending / torsional mode vibrations of powertrain assembly. This aggravates other concerns such as shift lever vibrations, shift lever rattle, rise in in-cab noise, generation of boom noise at certain speeds, etc. Hence, reducing vibrations becomes an important and difficult aspect in design of an automobile.
Journal Article

Front-Loading of Occupant Ingress-Egress Targets in Vehicle Architecture

Achieving comfortable Ingress-Egress (I/E) is a major ergonomic challenge for Occupant packaging engineers during vehicle design. Vehicles should be designed so that the targeted drivers are able to comfortably get in and out of it. Simulating occupant ingress/egress motion for vehicle involves many constraints and capturing actual behavior of human motion is cumbersome. In recent years, there are number of studies to investigate occupant ingress/egress motion and to understand perceived discomfort, influence of specific design parameters, age impact etc. These studies majorly used techniques like real time motion capturing in a vehicle mockup, comparison of joint torques developed during the ingress/egress motions etc., to identify the occupants discomfort aspects. This paper aims to capture the ingress/egress influencing parameters and incorporating the parameters in vehicle architecture layout during concept phase itself considering various anthropometric measurements.
Technical Paper

Migration Phenomenon in Gear Teeth of Hypoid Crown Wheels (Ring Gears) - Controlling and Eliminating the Same in Manufacturing

The paper talks about the migration phenomenon that is observed in gears. The phenomenon discussed here is that observed on hypoid gears which due to their high spiral angles cause the issue to be more sensitive, but the analogy to other gears is applicable. Mahindra manufactures hypoid gear sets for its axles in-house that go on a wide range of its products; with performance benefits also come the stringent quality requirements for hypoid gear sets. Migration is the phenomenon that causes the furling or unfurling of individual gear teeth with respect to each other. This in effect causes the circular tooth spacing between two teeth to become non-uniform. This has a direct effect on the performance of the mated gear set.
Technical Paper

Novel Approach for Model-Based Development - Part II: Developing Virtual Environment and Its Application

With continuous pressure for reducing vehicle development time and cost, without compromising on system reliability, it is imperative to move from Road to Lab to Model (RLM) based development. Every OEM is currently using virtual environment to complete functional checks of systems during development. The method of developing control functions and calibration in virtual environment brings repeatability and reproducibility which typically is challenging in real world testing. This process is cost effective and optimizes the time for development and brings high level of system maturity before testing it in the vehicle. This paper focuses on defining a front-loading approach for setting up of virtual test environment. Development of virtual test environment and its validation with respect to real vehicle data will be discussed, with focus on vehicle plant model and driver model.
Technical Paper

Novel Approaches for Model-Based Development - Part I: Developing a Real-World Driver Model

OEMs these days are focusing on front loading the activities to Virtual Test Environment (VTE) based development owing to high development cost and complexity in achieving repeatability during testing phase of vehicle development,. This process not only helps in reducing the cost and time but also helps in increasing the maturity and confidence level of the developed system before actual prototype is built. In the past, extensive research has happened for increasing the fidelity of VTE by improving plant model efficacy which involves powertrain and other vehicle systems. On the other hand, improving the precision of driver model which is one of the most complex nonlinear systems of virtual environment still remains a challenge. It is apparent that various drivers show different behavior in real world for a given drive profile. While modelling a driver for a VTE, the real world driver attributes are seldom considered.
Technical Paper

Development of Indian Digital Simulation Model for Vehicle Ergonomic Evaluations

Virtual assessment of an occupant postural ergonomics has become an essential part of vehicle development process. To design vehicle for different market is one of the primary reason for manufacturers using digital tools to address the specific needs of the target market including cultural background, road and traffic conditions. RAMSIS is a widely used software for creating digital human models (DHM) of different target population which allows manufacturers to assess design with unique customer requirements in product design. Defining these requirements with RAMSIS human module helped development team to accurately define occupant targets such as occupant space, visibility and reachability etc. Occupant behavior and usage scenario are factors which are unique to target market and they influence the occupant posture and usage pattern inside the vehicle. This paper defines the methodology towards the development of Indian Digital Simulation model for vehicle ergonomic evaluations.
Technical Paper

Life Estimation and Thermal Management of a 48V Mild-Hybrid Battery Pack

The 48V mild-Hybrid system uses a 48V Lithium - Ion battery pack to boost the engine performance, to harness recuperative energy and to supply the accessory boardnet power requirement. Thermal management of the 48V battery pack is critical for its optimal utilization to realize the mild hybrid functionality, to meet CO2 reduction targets and useful life particularly under usage in hot ambient conditions. This paper discusses the various challenges and options of thermal management for the 48V battery pack based on the usage pattern and environmental conditions. The lifetime for a passively cooled battery pack is estimated for a typical Indian usage pattern. Active-air cooling is evaluated for the thermal management of the 48V mild-Hybrid battery pack. The tradeoffs are compared in terms of availability of hybrid functions and battery life.
Technical Paper

Identification and Resolution of Vehicle Pull and Steering Wobble Using Virtual Simulation and Testing

A vehicle drifts due to several reasons from its intended straight path even in the case of no steering input. Vehicle pull is a condition where the driver must apply a constant correction torque to the steering wheel to maintain a straight-line course of the vehicle. This paper presents an investigation study into the characteristics of a vehicle experiencing steering drift. The aim of the work is to study vehicle stability and the causes of vehicle drift/pull during straight line to minimize vehicle pull level and hence optimize safety measures. A wobble in the steering wheel feels like the steering wheel is shaking to the left and right. This may get worse, if speed increases. This paper focuses on modelling and evaluating effects of suspension parameters, differential friction, brake drag variation, Unbalanced mass in the wheel assembly and C.G. location of the vehicle under multibody dynamic simulation environment.
Technical Paper

Front Loading of Foot Swing Envelop during Egress to Vehicle Architecture

In automotive industry, design of vehicle to end customer with proper ergonomics and balancing the design is always a challenge, for which an accurate prediction of postures are needed. Several studies have used Digital Human Models (DHM) to examine specific movements related to ingress and egress by translating complex tasks, like vehicle egress through DHMs. This requires an in-depth analysis of users to ensure such models reflect the range of abilities inherent to the population. Designers are increasingly using digital mock-ups of the built environment using DHMs as a means to reduce costs and speed-up the “time-to-market” of products. DHMs can help to improve the ergonomics of a product but must be representative of actual users.
Technical Paper

Underbody Drag Reduction Study for Electric Car Using CFD Simulations

Electric cars are the future of urban mobility which have very less carbon foot print. Unlike the conventional cars which uses BIW (Body in White), some of the electric cars are made with a space frame architecture, which is light weight and suitable for low volume production. In this architecture, underbody consists of frames, battery pack, electronics housing and electric motor. Underbody drag increases due to air entrapment around these components. Aerodynamic study for baseline model using CFD simulations showed that there was a considerable air resistance due to underbody components. To reduce the underbody drag, different add-ons are used and their effect on drag is studied. A front spoiler (air dam) is used to deflect the incoming air towards sides of the car. A under hood cover for front components, trailing arm cover for trailing arm and rear bumper cover for rear components were used to reduce underbody drag.
Technical Paper

In-Vehicle Visual Hindrance Free Positioning of Instrument Cluster

In-vehicle displays such as an instrument cluster in a vehicle provide vital information to the user. The information in terms of displays and tell-tales needs to be perceived by the user with minimal glance during driving. Drivers must recognize the condition of the vehicle and the state of its surroundings through primarily visual means. Drivers then process this in the brain, draw on their memory to identify problem situations, decide on a plan of action and execute it in order to avoid an accident. There are visual hindrances seen in real world scenario such as obscuration, reflection and glare on the instrument cluster which prevents the vital information flow from vehicle to the driver. In order to ensure safety while driving, the instrument cluster or driver displays should be placed in an optimized location. This paper deals with how to achieve a visual hindrance free cluster position in a vehicle to protect the important information flow from the vehicle to the driver.
Technical Paper

Hardware and Combustion Optimization Strategy to Reduce Engine Out Emissions for BS V Limits

With growing need for air quality improvement the emission norms are becoming stringent than ever, triggering a challenge for OEMs. This is because selection of appropriate technology to meet stringent emission standard and engine performance has to be ensured with improved fuel efficiency, and control cost. To comply with future emission standards, intensive efforts are required to optimize the overall engine out emissions with reduce dependency on exhaust after treatment systems. This paper highlights about strategies employed in developing BS V emissions compliant engine for SUV application. The authors have assumed the limits of EURO 5 emission norms as equivalent to BS5 for this purpose. An existing BS IV compliant engine is selected as a base engine and engine out emission targets were defined considering certain conversion efficiency for the after treatment system.
Technical Paper

Front Loading In-Vehicle Traffic Light Visibility Requirements for Driver as per Indian Road Standards

Traffic awareness of the driver is one of the prime focus in terms of pedestrian and road safety. Driver experience plays a significant role and driving requires careful attention to changing environments both within and outside the vehicle. Any lapse in driver attention from the primary task of driving could potentially lead to an accident. It is observed that, lack of attention on the ongoing traffic and ignorant about the traffic information such as traffic lights, road signs, traffic rules and regulations are major cause for the vehicle crash. Traffic signals & signage are the most appropriate choice of traffic control for the intersection, it is important to ensure that driver can see the information far away from the intersection so that he/she can stop safely upon viewing the yellow and red display. Then, upon viewing the signal operations and conditions the motorist can stop his/her vehicle successfully before entering the intersection.
Technical Paper

Innovative Method of Calibration to Meet BS4 Emission with Optimized Fuel Economy and Noise in a MPV with 2.5Lit Common Rail Diesel Engine

In today's fast growing automobile world, the Emission limits are stringent; customer expectations of vehicle performance and Fuel economy are more. Achieving these parameters for the given engine are challenging task for any automobile engineers. BS4 Emission limits are 50% more stringent than BS3 limits and from April 2010 onwards, all passenger cars which will be selling in 13 metro cities in India should be BS4 emission compliant. In this paper, we have described how BS4 limits were achieved in a MPV with 2.49 l, 70kW Common Rail Direct Injection Turbocharged Diesel engine, with push rod. During Emission development, the following processes were followed to meet BS4 emission limits without sacrificing the engine performance, Fuel Economy and Noise. Selecting suitable hardwares like Turbocharger, EGR cooler at engine level to reduce NOx and Unburned Hydrocarbon Emissions with best Brake specific fuel consumption.
Technical Paper

Intake System Design Approach for Turbocharged MPFI SI Engine

The automotive industry is currently facing the challenge of significantly stringent requirements regarding CO₂ emission and fuel economy coming from both legislations and customer demand. Advanced engine technologies play a vital role for downsizing of gasoline engine. The development of key design technologies for high efficiency gasoline engines is required for the improvement of competitive power in the global automobile industry. This paper focused on effect of geometry of intake manifold of gas exchange process and consequently the performance of the engine. Specially, the optimal design technologies for the intake manifold and intake port shape must be established for high performance, increasingly stringent fuel economy and emission regulations. Space in vehicle or packaging constraints and cost are also important factors while consideration of the design.
Technical Paper

Optimization of the Passenger Airbag Module to Meet Interior Fittings Compliance Requirements of ECE R21

Airbags play a vital role in occupant protection during a crash event. Apart from the crash test the airbags have to additionally meet the requirements of the ECE R 12 headform impact test with Driver's Airbag (DAB) located in the steering wheel being deployed and the ECE R21 headform impact test for Passenger Airbag (PAB) in undeployed condition. Improper location of the PAB module below the Instrument Panel, the design of the air bag housing and the Instrument Panel are some of the factors that could lead to non compliance of the components of the uninflated PAB. The paper deals with the investigation conducted for compliance of the PAB to ECE R 21 with the uninflated air bag in meeting the requirements of 80 g at 19.3 km/h by proper location, changes to the design of the PAB cover, air bag housing brackets, etc.
Technical Paper

Experiences in improving the Low end performance of a Multi Purpose Vehicle (MPV) equipped with a common rail Diesel engine.

Continually increasing customer demands and legislative Requirements regarding fuel economy, emissions, Performance, drive ability and comfort need to be met by every OEM's developing vehicles worldwide. There is a serious pressure to reduce CO2 emission from automotive application which contributes to around 15.9% of the total CO2 production based on the Surveys done time to time. In a developing market like India, many foreign players are entering with lots of option for offering to this market. The parameters of prime importance here are fuel efficiency with good drive ability and at the same time affordable price. Diesel engines are finding these benefits and attracting the buyer over its counterpart (Gasoline). The road condition and the driving pattern in India compared with developed countries differ to a major extent. In India, the Low speed uses are predominating in Cities and in Ghats.