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Technical Paper

Simulation of Gear Shift Force Curve and Shift Rail Ramp Profile

This paper presents a simulation for the gear shift process of a manual transmission, implemented using a library function. All the subsystem (i.e. synchronizer and the shift system) are correlated to generate a gear shift curve for optimum shift ability prediction of a manual transmission. A 5-speed manual transmission is used as an example in the paper to illustrate the simulation, co-relation and the validation of the gear shift performance curve on the vehicle. The dynamic behavior of the shift system and synchronizer in engaging and disengaging the gear is simulated through the gear shift characteristics to generate the shift rail's ramp profile. The synchronizer travel is co-related with the shift rail ramp profile to get a negative force after synchronization is over. The profile indicates the role of the detent ball diameter, radius on the shift rail ramp's profile etc and how it affects synchronizer force over the shift rail travel.
Technical Paper


Material selection is based on Process such as forging, die-casting, machining, welding and injection moulding and application as type of load for Knife Edges and Pivots, to minimize Thermal Distortion, for Safe Pressure Vessels, Stiff, High Damping Materials, etc. In order for gears to achieve their intended performance, durability and reliability, the selection of a suitable gear material is very important. High load capacity requires a tough, hard material that is difficult to machine; whereas high precision favors materials that are easy to machine and therefore have lower strength and hardness ratings. Gears are made of variety of materials depending on the requirement of the machine. They are made of plastic, steel, wood, cast iron, aluminum, brass, powdered metal, magnetic alloys and many others. The gear designer and user face a myriad of choices. The final selection should be based upon an understanding of material properties and application requirements.
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.
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

Development of a Free Motion Headform Impactor

The development of interior fittings of passenger car to minimize the injuries to the head of the occupants requires mandatory compliance to the regulations in Europe and USA. In European regulation ECE R21 and similarly in FMVSS 201 the test on the instrument panel area suffices. The FMVSS 201u requirements in USA require also a free motion headform to be impacted on additional areas of the A-Pillar trim, sun visors, grab handles, and seat belt upper anchorage points of the B-Pillar too. Free Motion Headform Impactors (FMHI) are costly equipment. The FMVSS 201u [1] test is not conducted by any test agency in India as yet. Paper deals with the development of the head form impactor to fire the headform at angular positions in the vehicle and the test results have enabled the development of the vehicle interiors to enhance the safety of vehicles in crash situations.
Technical Paper

Development of Common Rail Engine for LCV BS III and a Step Towards BS IV Emission Compliance

This work discusses about the emission development of a 4 cylinder inline 3.3 liter CRDe to meet BS III emission norms applicable to 3.5 Ton and above category and upgradable to BS IV emission by suitable after treatment. This engine is developed from a 3.2l mechanical pump engine. During development the focus was on the usage of higher swept volume, selection of engine hardware like piston bowl, turbocharger, injectors and optimization of the injection parameters. A cost-effective solution for meeting the BS III norms in the LCV category without application of EGR and exhaust after treatment even though there is 15% increase of the power rating and 10% increase in Peak torque of the engine. Injection parameters like injection timing, injection quantity and pilot injection were optimized to meet the emission target.
Technical Paper

Shift System Inertia Mass Optimization Techniques to Minimize Double Bump for Manual Transmission

The demand of gear shift quality in vehicles has increased considerably in the past few years. The gear shift is the key interface between driver and vehicle transmission. The essential criterions for the operating quality of the gear shift is the operating force and feel on the gear shift knob at each stage of gear shift, starting from start of gear shift to the end of gear shift. This paper deals with techniques to reduce secondary force due to synchronizer sleeve hitting on dog ring at the end of gear shift which is also known as Double Bump. The double bump ratio should be less than 0.4 to achieve the best in class shift feel for passenger car segment. Normal driver will not feel if double bump ratio is less than 0.6. Inertia mass mounted on shift system of manual transmission helps to generate momentum at the end of gear shift to nullify the double bump force.
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

A Supervisory Learning Based Two-Wheeler Drive Pattern

The life of a two-wheeler and its parts depend much on its usage during its years of running. The quality of its parts determine the life and efficiency; however the handling of the two-wheeler also plays a major role in estimating it's life and other performance parameters. Hence, it is beneficial to have an efficient system which enhances the life of a two-wheeler and also gives better mileage. This paper constitutes an efficient drive pattern system which addresses the above. This system consists of two main parts: the data collection system and an Android-based mobile application which runs on a mobile phone. The data collection system collects data from various sensors on the vehicle and then the data is processed and sent to the mobile phone of the rider during the run time of the two-wheeler. The application uses this data to depict useful information like drive pattern and various indicators.
Technical Paper

Scaling Model of Heat Exchangers in Automotive Air Conditioning Systems

Heat exchangers are thermoregulatory system of an automotive air conditioning system. They are responsible for heat exchange between refrigerant and air. Sizing of the heat exchanger becomes critical to achieve the required thermal performance. In the present work, the behavior of heat exchanger with respect to change in size is studied in detail by developing a scaling model. The limited experiments have been conducted for 3 different condensers. Commercially available 1D tool GT Suite is used for simulations. The heat exchangers are modeled using COOL3D module of GT Suite. The experimental thermal capacities of heat exchanger are compared with the simulated values. A good agreement up to ±2.3% is found between the experiments and simulations. Then developed scaling model in GT Suite is used for predicting the thermal behavior of heat exchangers by changing the size of the heat exchanger. Scaled thermal capacities of each model is compared with the corresponding experimental results.
Technical Paper

Studies on Neutral Gear Rattle in Early Stage Design

In today's competitive automobile market, customers have become more sensitive towards NVH behavior of the vehicle than ever. The noise generated by gear rattle is one of the main contributors towards customer's overall NVH perception. This paper adopts a model based design approach towards gear rattle phenomenon to predict the tendency of gear rattle at a very early stage of design. This up-front understanding of gear rattle will potentially reduce the expensive design changes and iterations at later stages. A single unloaded gear pair is modeled in AMESim software, which is then extended to the complete gearbox in neutral condition. The sensitivity of rattle index for different input parameters is studied. Analysis on uncertainty propagation is carried out to find the rattle index distribution for Gaussian variation of input parameters. A novel rattle index based on Jerk is proposed and compared with the existing index.
Technical Paper

Experimental Approach to Improve the Door Slam Noise Quality in Utility Vehicles

The customer perception about the door slam noise and its feel would indicate the brand image of the car. In this paper the authors have made an effort to improve the door slam noise quality of the vehicle, which is currently in production. This paper describes the probable areas in the door to improve the slam noise quality by attempting modifications in the door design factors, such as door alignments, door panel stiffness, door trims, window glass rattle, latch striker alignment, door seals, air extractor. Since the door closing event is a transient phenomenon, it requires special tools such as wavelet transforms, Zwicker loudness to understand the slam events precisely. Subjective jury evaluations have been conducted to understand the effect of these modifications and rank the modifications based on their contributions to the door slam quality.
Technical Paper

Evaluation and Comparative Study of ValveTrain Layouts with Different Rocker Ratio

The Valve Train system is an integral part of any engine and the impact of its design is very crucial, particularly in high speed engines. Maintaining the required valve timing throught the engine operating speed and longer component life are the two important parameters which drive current valvetrain designs. An engine ValveTrain system designed for a valve lift of 7mm is to be modified for an increased valve lift of 8mm. A study was conducted to understand which design parameters are to be changed /modified to make this possible. For this study, the valvetrain of an air-cooled motorcycle engine is taken up. The valvetrain arrangement was an Over Head Camshaft (OHC) design with a Roller-Follower. A 1D commercially available numerical code was used to simulate the kinematics and dynamics of the system.
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, Compact and Light Weight Plenum Assembly for Automobiles

Plenum is the part located between the front windshield and the bonnet of an automobile . It is primarily used as an air inlet to the HVAC during fresh air mode operation. It’s secondary functions include water drainage, aesthetic cover to hide the gap between windshield to bonnet, concealing wiper motors and mechanisms etc. The plenum consists mainly two sub parts viz. upper plenum and lower plenum. Conventional plenum design which is found in majority of global OEMs employ a plastic upper plenum and a metal lower plenum which spans across the entire width of engine compartment. This conventional lower plenum is bulky, consumes more packaging space and has more weight. In this paper, we propose a novel design for the plenum lower to overcome above mentioned limitations of the conventional design. This novel design employs a dry and wet box concept for its working and is made up of complete plastic material.
Technical Paper

Detent Profile Optimization to Improve Shift Quality of Manual Transmissions

The customer of today is sensitive towards shift quality. The demand is for a crisp and precise gear shift with low shift effort. The impulses from synchronizers make shifts feel notchy. After synchronization the blocker ring releases the sleeve. The sleeve then hits the teeth of the clutch body ring. The second impulse causes a phenomenon called double bump. This can be felt at the hand and makes a shift feel notchy or sluggish. An ideal way to overcome this is to optimize the detent profile. This paper explains in detail the various factors that contribute to the perceived shift feel. Various methods to optimize the forces on the knob by changing the detent profile are discussed. Gear Shift Quality Assessment (referred as GSQA henceforth) is a tool to acquire the required shift feel data. Using this tool shift efforts and kinematics of a 5 speed manual transmission are plotted for illustration. The calculations required to optimize the detent profile are explained in detail.
Technical Paper

Manufacturing of Transmission Quill Gear by Sinter Hardening

Transmission quill gears are hot forged steel parts often used in constant mesh manual transmissions. The quill gear, which helps to transmit the power from input drive shaft to output shaft through driving gears. It’s having external teeth which is positively engaged with driving gear and sleeve. During gear selection sleeve take load from input shaft and transmit to driven gear. Quill gear directly engaged with driving gears on outer surface and bearing in inner surface which needs to have high strength and durability. These properties can be improved by carburization heat treatment in existing design such processes can lead to increased costs. We have developed quill gear through powder metallurgical process and then cooled rapidly in the furnace to get high strength and wear properties. Material composition are optimized to suit for sinter hardening process conditions.
Technical Paper

Analytical Approach to Gear Reverse Engineering (Spur and Helical)

In today's automotive industry Benchmarking plays a vital role to improve performance, quality of critical functions and key areas of an organization by understanding and evaluating the products & processes in relation to Best Practices. Gear Reverse Engineering (here in after called as GRE) a part of Benchmarking is an activity which follows an analytical approach to calculate basic key parameters for an unknown gear pair. This paper propose a diagnostic tool/method, which determines basic gear parameters for an unknown gear pair, by simply measuring few dimensions as input followed by step wise analytical approach. This tool/method simplifies the gear designer job at initial stage by eliminating frequent trial & errors, iterations and complex measurements, which saves time & cost.
Technical Paper

Methodology to Performance Verification of Close Gear Ratios for SUV

In automotive world, SUV required more powerful, high pickup as well as best acceleration performance driveline that study reaches to close gear ratio transaxle, so this paper presents the gear ratio’s performance (Torque and Acceleration) in terms of comparative analysis for close vs. wide ratios for six speed manual transaxle (250 Nm torque capacity), having center distance of 85 mm. The gear performance and comparative analysis test has been carried out to achieve good performance in terms of drivability (speed, torque, gradabeality) and their results are compared with theoretical calculations. For Validation of each gear ration’s performance has analyzed by using test rig and correlated their results with torque values. The close ratios selection has been done by using calculation and comparison, for such concept developed performance prediction excel sheet, results are tabulated and finally represents through graph.
Technical Paper

Evaluation of Vehicle Systems Structural Durability Using PSD Based Fatigue Life Approach

In current competitive environment automobile industry is under heavy pressure to reduce time to market. First time right design is an important aspect to achieve the time and cost targets. CAE is a tool which helps designer to come up with first time right design. This also calls for high degree of confidence in CAE simulation results which can only be achieved by undertaking correlation exercises. In automobiles most of the structures are subjected to vibration from dynamic loads. All the dynamic road loads are random in nature and can be very easily expressed in terms of power spectral density functions. In the current scenario structural durability of the parts subjected to vibration is done partially through modal performance and partially though frequency response analysis. The only question that arises is what amplitude to use at what frequency and how to map all the accelerated tests dynamic load frequency spectrum to simulation domain.