Search Results

In modern automotive vehicles, there is a major concern for noise and vibrations generating from drivetrain. These noise and vibrations affect the passenger comfort and drivetrain parts life. Engine generates fluctuating torque and causes angular acceleration that results into torsional vibrations. These vibrations are transmitted to powertrain. Clutch disc consists damper springs and hysteresis which aids reducing these torsional vibrations. Based on the damper spring stiffness, one can control the resonance speed range and shift the resonance rpm out of driving speed range of engine. The resonance should not happen within driving speed range of vehicle to avoid large amplitude torsional vibration. But here limitation is put on the torque transmission capability of clutch for meeting vehicle requirements. As, low stiffness of damper spring requires large wind-up angle so, it is critical to decide its stiffness.

Gear rattle is due to impact noise of unloaded gears in transmission having freedom to move in backlash region. Engine order vibrations in the presence of backlash in meshing pairs induce the problem. It is a system behavior wherein flywheel torsional vibrations, the pre-damper characteristics and transmission drag torque plays a vital role in an engine idle condition (hot & cold). Idle rattle is a severe issue, which is highly noticeable in cold condition or after 1st engine crank. Gear rattling observed in idle condition is idle gear rattle or neutral gear rattle, specifically in cold condition is a “Cold idle rattle” and this is one of the critical noise parameters considered for entire vehicle NVH. Damper mechanism in the clutch, is used to serve better isolation (by reducing the input excitation to transmission parts) of vibrations between engine and transmission their by reducing gear rattle intensity.

Gearbox and driveline durability is always been a sensitive subject from both end user and manufacturer’s point of view. Since powertrain is heart of vehicle, naturally it is expected to long last and perform satisfactorily for the entire vehicle life. Sometimes the driveline aggregates especially gearbox might face some issues because of various factors, but this is distinctively noted by the driver since it is one of the important touch point of the vehicle. The gear slippage is a very typical phenomenon observed in automotive gearbox. The issue of gear slippage is very sensitive because it leads to compromising safety of the driver, also it deteriorates gear shift quality and thereby performance of the vehicle. Generally, gear slippage is not observed during end of line testing or during early kilometers of vehicle. It is observed after some thousand kilometers, that to initially gear slippage is not observed consistently and that’s why it is difficult to identify at early stage.

The public transport in India is gradually shifting towards electric mobility. Long range in electric mobility can be served with High Voltage Battery (HVB), but HVB can sustain for its designed life if it’s maintained within a specific operating temperature range. Appropriate battery thermal management through Battery Cooling System (BCS) is critical for vehicle range and battery durability This work focus on two aspects, BCS sizing and its coolant flow optimization in Electric bus. BCS modelling was done in 1D CAE software. The objective is to develop a model of BCS in virtual environment to replicate the physical testing. Electric bus contain numerous battery packs and a complex piping in its cooling system. BCS sizing simulation was performed to keep the battery packs in operating temperature range.

Automotive suspension system forms the basis for the design of vehicle with durability, reliability, dynamics 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 ductility, monotonic and cyclic mechanical properties. Furthermore, welding processes offer design flexibility to achieve robust and lightweight designs with high strength steels.

Small commercial vehicles (SCVs) are the drivers of a major part of India’s indirect economy, providing the most efficient means of transport. With the introduction of BS-VI norms, some major overhauls have been done to the SCV models to meet BS VI norms in challenging timeline for early market entry. This forced to automotive designers towards challenge of cost competitiveness as well as refinement level to survive in this competitive market. This paper explains the systematic approach used to overcome challenges of higher tactile vibrations, higher in-cab noise because of BS VI requirement in 2 cycle engine required for small commercial vehicle. The solutions were need to be worked out without compromising the other performance attributes like total cost of ownership, fuel economy, ease of servicing and cost effectiveness.

Normal engine mounting system is designed to carry loads of powertrain in all driving conditions and also isolate the vibrations of powertrain. Softer mounts are good for vibration isolation but it is not recommended to have softer mounts because durability will be affected adversely. Optimum stiffness needs to be finalized which will have balance between durability and performance. In addition to durability many performance parameters needs to be checked during the time of development. This study includes the development of engine mounting system for elimination of drive away judder in first gear. Maximum peak torque value for the drive-away event is in the range of 80Nm - 120Nm. In the worst case, this peak torque can reach to maximum 170Nm depending on maneuver, engine rpm is around 1100-1200. Steering wheel, instrument panel and whole vehicle cabin will vibrate for few seconds and then vehicle will run smoothly.

Environmental regulation, operating cost reduction and meeting stringent safety norms are the predominant challenges for the automotive sector today. Automotive OEMs are facing equally aggressive challenges to meet high fuel efficiency, superior performance, low cost and weight with enhanced durability and reliability. One of the key technologies which enable light weighting and cost optimization is the use of fiber reinforced polymer (FRP) composite in automotive chassis systems. FRP composites have high specific strength, corrosion and fatigue resistance with additional advantage of complex near net shape manufacturing and tailor made properties. These advantages makes FRPs an ideal choice for replacing conventional steel chassis automotive components. However, FRP’s face challenges from operating environment, in particular temperature and moisture.

The small commercial vehicle business is driven by demand in logistic, last mile transportation and white goods market. And to cater these businesses operational and safety needs, they require closed container on vehicle. As of now, very few OEM’s provide regulatory certified container vehicle because of constrains to meet inertia class of the vehicle. This paper focuses on design of a durable and extremely reliable container, made of the low-cost economy class glass fibre & core material. The present work provides the means to design the composite container for the N1 category of the vehicle. The weight of after-market metal container ranges between 300-350 Kg for this category of vehicle, which affects the overall fuel economy and emission of the vehicle. A detailed CAE analysis is done to design composite container suitable to meet inertia class targets and to achieve weight reduction of 30-40% as compared to metal container.

With the advent of BS VI regulations, automotive manufacturers are required to innovate the powertrains, fuel systems, exhaust and its after treatment systems to meet the regulatory requirements. The exhaust regulations can be met either by reducing the exhaust gases being generated by the engine (attacking the source) or by treating the exhaust gases in after treatment devices. The choice of the opted system varies with the manufacturer. The after-treatment devices such as catalytic converters are generally mounted in the engine compartment to take advantage of high temperature of exhaust gases to yield the reactions. Such an arrangement imposes a lot of thermal load on the peripheral components such as gearshift cables, bearings, oil seals, driveshafts etc. Thermal shields or thermal sleeve are used to address thermal issue and to protect transmission components.

The automotive sector is going through a phase of stiff competition among various Original Equipment Manufacturers for increasing their profitability while ensuring highest levels of customer satisfaction. The biggest challenge for such companies lies in minimizing their overall cost involving investments in Research and Development, manufacturing, after sales service and warranty costs. Higher warranty costs not only affect the net profit but in turn it also affects the brand image of the company to a large extent in the long run. An effort is made here to target such warranty costs due to frequent tail pinion and hub seal leakages on single reduction/hub reduction axles of Heavy Commercial Vehicles in the field. A preliminary study involving the severity analysis of such failures is followed by a step by step investigation of these failures.

Interdependency of automotive transmission aggregates on electrical/ electronics systems is increasing day by day, offering more comfort and features. For a system integrator, it becomes very much important while selecting/designing any such component to take into consideration the relationship between such interdependent components from performance as well as endurance point of view. DMF failures due to inadequate starting system, is a major stumbling block in development of DMF for a particular vehicle application. The interface of DMF and starting system of a vehicle makes it essential to consider the effect of one on another. The study shows that the majority of DMF failures happen because of resonance phenomenon in the DMF during engine starting. The improper selection of starter motor makes the DMF more vulnerable for such failures.

Crank train torsional vibration is an important aspect for design and development of Powertrain for NVH refinement and durability. Crank train torsional vibration parameters like angular acceleration of flywheel or twist, depends upon various design parameters like geometry of crankshaft, mass of flywheel, stiffness of clutch, mass of pulley etc. It also depends upon engine operating conditions like engine speed, engine load, combustion peak pressure and combustion pressure variation etc. Most of these parameters are decided by engine power, torque, engine architecture and packaging constraints. Addition of torsional vibration damper (TVD), which works on the principle of tuned dynamic absorber, is commonly deployed design solution to control the torsional vibrations as well as stresses (to improve durability of crank train) induced in crank train assembly at specified modal frequency.

The entire commercial vehicle industry is moving towards weight reduction to leverage on the latest materials available to benefit in payload & fuel efficiency. General practice of weight reduction using high strength steel with reduced thickness in reference to Roark’s formula does not consider the stiffness & dent performance. While this helps to meet the targeted weight reduction keeping the stress levels within the acceptable limit, but with a penalty on stiffness & dent performance. The parameters of stiffener like thickness, section & pitching are very important while considering the Stiffness, bucking & dent performance of a dumper body. The Finite Element Model of subject dumper body has been studied in general particularly on impact of dent performance and is correlated with road load data to provide unique solution to the product. The impact of payload during loading of dumper is the major load case.

There has been immense focus on Gear Shift Quality as it is seen as an important factor for subjective evaluation of driving comfort of a vehicle with manual transmission. Synchronizer and driveline stiffness optimization is often the only area of focus for gear shift quality during early design stage. Proven Simulation models are already available for predicting the effect of synchronizer and driveline stiffness. Though Gear shift cable also has a significant effect on gear shift quality, neither design guidelines nor simulation models are available for predicting gear shift cable performance. Designers have relied on physical approach to establish cable routing, since cable routing cannot be predicted on virtual vehicle. In design phase cable routing is imagined and modeled in CAD using constrained curve geometry and later on established by physical trials on vehicle with various cable lengths, routing paths and clamp positions.

Hybridization of vehicle drive train is an important step to increase energy security, reduce crude oil import, improvement of air quality and GHG reduction. Heavy traffic congestion poses a great challenge in improvement of fuel economy. Nowadays urban climatic condition forces the passenger to keep air-conditioning (AC) on; thus further decreasing the fuel economy. In a typical urban drive; the vehicle commutes with low speed forcing IC Engine to run in its low efficiency operational points. Further it is characterized by frequent start-stop and crawling. It has been observed that the power consumption for AC is comparable to that required for the vehicle propulsion. Hence the AC on condition with propelling vehicle demands higher power from engine creating a challenge for fuel economy improvement.

In today’s automobile market, most OEMs use manual transmission for cars. Gear Shifting is a crucial customer touch point. Any issue or inconvenience caused while shifting gears can result into customer dissatisfaction and will affect the brand image. Synchronizer is a vital subsystem for precise gear shifting mechanism. Based on vehicle application selection of synchronizer for given inertia and speed difference is a key factor which decides overall shift quality of gearbox. For more demanding driver abuse conditions like skip shifting, conventional brass synchronizers have proved inadequate for required speed difference and gear inertia, which eventually results into synchronizer crashing and affects driving performance. To increase synchronizer performance of multi-cone compact brass synchronizer, a ‘Grit blasting process’ has been added. These components tested with an accelerated test plan successfully.

Electrical and Series Hybrid Vehicles are generally provided with single speed reduction gearbox. To improve performance and drive range, a two-speed gearbox with coordinated control of traction motor and gearshift actuator is proposed. For a two-speed gearbox, gearshift without clutch would increase the shifting effort. Active Synchronization is introduced for a smoother gearshift even without clutch. The quality of gearshift is considered as a function of applied shift force and time taken. To enhance the quality of the gearshift further, the location of the synchronizer in the transmission system is optimized. To validate the improvement in the quality of the gearshift, a mathematical model of the two-speed gearbox incorporating proposed location of synchronizer assembly along with active synchronization is developed. The qualitative and quantitative analysis of the results achieved is presented.

Basic Function: Vehicle remote is used for vehicle lock/unlock/search/Hazard lights /approach light functions for customer convenience and vehicle security system. Conventional approach: 1 Use of separate RF (Radio Frequency) receiver -Additional Cost impact. 2 High remote RF power - Reduced remote battery life and bigger remote size required 3 High sensitivity RF receiver - High cost. Low Cost approach: It involves the followings: 1 Integration of RF receiver inside the Body Control Module (BCM). 2 Low Power Remote and Optimization of Remote PCB layout to get the maximum power. 3 External wired antenna taken out from BCM and proper routine need be ensured to get the best performance. 4 BCM mounting location to get the best remote range in all vehicle directions. This paper relates to the methodology for low cost approach for the RF communication between remote transmitter and receiver with achieving the best remote performance at vehicle level condition.

Power-supply forms a key hardware block for every automotive ECU. Apart from delivering robust and reliable logic supply voltages it is also burdened with many auxiliary tasks like transient protection, good EMI/EMC performance, Power-hold function, Analog Sensor supply voltage etc. It also needs to meet all automotive norms including short to battery/ground etc. This paper discusses low cost implementation techniques which maximize the value delivered to the vehicle application at minimal cost. Innovative techniques are described for combining sensor and logic supplies wherever applicable. Hurdles faced during such circuit optimization are clearly explained along with the solutions adopted to overcome hurdles yet meeting automotive test norms. A novel low cost concept which combines transient protection as well as power-hold function (without using the conventional relay based technique) further adds value to the end application.