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Pneumatic brake system is widely used in heavy truck, medium and heavy buses for its great superiority and braking performance over other brake systems. Pneumatic brake system consists of various valves such as Dual Brake Valve (DBV), Quick release Valve (QRV), Relay Valve (RV), Brake chambers. Dynamics of each valve is playing a crucial role in overall dynamic performance of the braking system. However, it is very difficult to find the contribution of each valve and pipe diameters in overall braking performance. Hence, it is very difficult to arrive a best combination for targeted braking performance as it is not possible to evaluate all combination on the actual vehicle. Hence, it is very important to have a mathematical model to optimize and evaluate the overall braking performance in early design phase. The present study is focusing on the mathematical model of a pneumatic brake circuit.

Use of diluting agents in neat vegetable oil to reduce its density and viscosity, is arguably the best alternative route for vegetable oil usage in diesel engines. It is suitable where the complex transesterification process for biodiesel production is not feasible. In this study, Calophyllum vegetable oil was diluted with 10%, 20% and 30% by volume of Isopropyl alcohol and named as CI10, CI20 and CI30 respectively. Neat diesel was termed as D100. An exhaustive field trial on a single cylinder agricultural diesel engine indicated that full load brake thermal efficiency of D100 was 26.4% followed by CI10, CI20 and CI30 test fuels. Emissions of carbon monoxide, hydrocarbons and smoke were impressively reduced by a margin of 17-63% for the isopropyl alcohol containing test fuels as compared to the diesel baseline. However, oxides of nitrogen emissions were marginally higher for the isopropyl alcohol blends.

The heat losses through exhaust gases and the engine coolant contribute significantly towards reduction in thermal efficiency of an Internal Combustion (IC) engine. This largely impacts the fuel economy and power output. Waste Heat Recovery (WHR) has proven to be an effective method of overcoming these challenges. A Rankine cycle is a reverse refrigeration cycle that circulates a working fluid through the four basic components namely the pump, evaporator, turbine and condenser. It is a popular WHR approach in automotive applications with varying levels of success in the past. As the heat transfer capability in organic working fluids is greater than the conventionally used inorganic fluids, the former is used to capture maximum waste heat from low grade heat sources such as the automobile engine. A dual-loop Organic Rankine Cycle (ORC) is proposed for a heavy duty IC Engine with working fluids R245fa and R236fa for the High Temperature (HT) and Low Temperature (LT) loops respectively.

This paper focuses on factors that enhance energy efficiency of air conditioning system on mid-sized, standard and premium buses with engine power from 125 to 280 HP. It covers aspects like light weighting of roof air conditioning system, usage of optimized ducting system with minimal resistance to blowers, deployment of rotary scroll compressor with fast idle control in place of reciprocating piston compressor. The scope of this paper covers AC compressors driven by main engine of vehicle/ bus, study related to auxiliary/donkey engine driven AC compressor is not considered. Context- In order to enhance fuel efficiency in buses an energy efficient air conditioning system should be deployed. This will lead to reduced parasitic load on the engine and translate into direct fuel saving.

In present commercial vehicles, the cranking torque required for a heavy duty compression ignition engine is very high. This results in higher durability and reliability requirement of cranking system components and also makes it cumbersome to implement start-stop micro hybrid feature which requires more number of cranking cycles in lifetime. Hence higher capacity starter motor and battery is being used for implementing start-stop feature. However this would result in cost and packaging issues. In order to implement start-stop feature maintaining the same starter motor and battery capacity, the cranking energy demand of the engine needs to be reduced. Studies conducted shows that the major source of breakaway torque is the work done in compression stroke during a starting cycle.

Best fuel efficiency is one of the core requirements for commercial vehicles in India. Consequently it is a central challenge for commercial vehicle OEMs to optimize the entire powertrain, hence match engine, transmission and rear axle specifications best to the defined application. The very specific real world driving conditions in India (e.g. traffic situations, road conditions, driver behavior, etc.) and the large number of possible commercial powertrain combinations request an efficient and effective development methodology. This paper presents a methodology and tool chain to specify and develop commercial powertrains in a most efficient and effective way. The methodology is based on the measurement of real world driving scenarios, identification of representative Real World Driving Profiles and vehicle system simulation which allows extended analysis of the road topography, the traffic situation as well as the driver behavior.

The running costs of heavy-duty trucks are strongly influenced by fuel consumption. Even a small improvement in fuel economy has a big effect on fleet cost savings and pollutant contamination. From the different possible sub-systems to be improved, reducing the rolling resistance of the tires is a cost-effective option due to its relatively high influence on the fuel consumption without negatively affecting the overall performance. Nevertheless, the other causes of resistance forces, such as mechanical friction and aerodynamics must be optimized as well. The focus of the work is to propose an accurate methodology specifically for heavy trucks for the proper evaluation of resistance forces to allow accurate fuel consumption simulation. For this purpose, the results obtained in proving ground were post-processed by applying different resistance forces characterization methodologies and the results were analyzed theoretically and numerically.

This study is made on a simplified pitch model of an armored fighting vehicle. Jerks and angular acceleration inside the vehicle compartment Affects accurate firing attack and reduced fatigue to the occupants in Vehicle. The Stability Augmentation Technique can enhance the stability and ride comfort of the vehicle platform from road and firing disturbance. The force requirement for stabilizing the platform is calculated from the displacement of vehicle body in terms of pitch angle and Heave displacement with respect to the equilibrium position, the equivalent force at suspension mounting points required to stabilize the platform is calculated using a force transformation technique. The required force is given by an active Damper for stabilization, within the limit of damper capacity.

In commercial vehicle, Leaf Spring design is an important milestone during product design and development. Leaf springs are the most popular designs having multiple leaves in contact with each other and show hysteresis behavior when loaded and unloaded. Commonly used methods for evaluation of leaf spring strength like endurance trials on field and Rig testing are time consuming and costly. On the other hand, virtual testing methods for strength and stiffness evaluation give useful information early in the design cycle and save considerable time and cost. They give flexibility to evaluate multiple design options and accommodate any design change early in development cycle. A study has been done in Volvo-Eicher to correlate Rig result with Finite Element Analysis (FEA) simulation result of Multi-stage Suspension Leaf Spring, entirely through Finite Element Analysis route.

CFD simulations of an engine cooling system needs to resolve two aspects of the system; in-cylinder combustion and engine cooling. Underlying physics of an in-cylinder combustion process and heat transfer through engine cooling system requires very different time scales for resolution. This puts a limitation on practicality of solving the two problems simultaneously for any industrial case. Instead of solving the problem simultaneously, solution for an engine cooling system operating at a constant load can be derived using the coupled approach. This involves running two different CFD simulations: a transient in-cylinder simulation to model combustion in the engine, and a steady state CHT simulation using engine cooling system for heat transfer. These simulations are thermally coupled through boundary conditions and are performed in cyclic manner one after the other. Simulations are continued till the change in temperature with coupled cycles becomes insignificant.

Basic driveline configurations offered in mid-size trucks have a standard “open” differential. Open differentials allow smooth cornering, as the outside tire must spin faster on corners as it travels a larger arc, when compared to the inner tire. This system has a main problem when traction is lost, due to slippery roads, different friction coefficients between pavements or even when the axle is submitted to a twist ditch. All of the power goes to the wheel with the least traction and the pickup is stuck. In order to improve traction on these situations, limited slip differentials were developed. A limited-slip differential will prevent excessive power from being allocated just to one wheel, and thereby keeping both wheels in powered rotation. There are several solutions offered in the market, each one presenting different torque transfer capabilities.

The higher is the volume of automated transmissions for high load capacity commercial vehicles in the market, the higher is the necessity to develop auxiliary systems capable to reduce the wear of the clutch disc during start-ability performance in slopped plans. The Hill Start Assist System, HSA, is compounded by a set of components in the brake system, disposed in such a way that provides to the driver the possibility of starting to run with comfort and safety by the actuation of the service brakes, without overheating the clutch system and simultaneously avoiding the undesirable effect of composition roll-back. For this, it is only necessary that the vehicle be equipped, besides automated transmission, Anti-lock Braking System, ABS, and an active traction control in, at least, one of the drive axles.

Fuel efficiency is an essential matter at commercial vehicle development. High fuel consumption of commercial vehicles has been considered synonymous with inefficiency or absence of available resources and budget to test more driveline configurations in different customer missions. The Brazilian market has a several request of mission profile, trailer configuration, load distribution, average speed, productivity and fuel economy target. Due to the increase of operational cost, customer expectation of profitability and market competition the company need create some different methodology to develop the best line up for each customer without impact on the program milestones and budget.

The present paper addresses an investigation about the definition of a parameter for quantifying the creep-groan propensity in brake pads. Creep-groan is a self-excited vibration caused by stick-slip phenomenon [1, 2, 3]. For the definition of the creep-groan propensity parameter, extensive experimental work was performed on a laboratory-scale tribometer. The experiments are divided in two main parts: (i) study of correlation between accelerometer signal with physical and operating parameters. (ii) validation of the chosen parameter, which was based on stick-slip tests performed with three different materials, one low-metallic (low-met) and two non-asbestos organic (NAO 1 and 2). From the first study, it was found that both the slip power and mean torque multiplied by torque variation showed a slightly higher correlation with the acceleration signal.

One effect which is present in drum and disc brakes is the temperature. This effect significantly changes the vehicle and semi-trailer combinations performance, mainly in drum brakes that is more susceptible to this factor. High temperatures mean loss of efficiency, higher lining wear, brakes and rolling systems components life reduction and could be caused by many factors, which can be mentioned, overload, error in design and choice of brake system, speeding, over adjustment (dragging) and environment heat exchange. The challenge is to comprehend the relation between different brake configuration and how these configurations affects the temperatures generation on brake system, allowing that this factors can be evaluated during the project design. This paper aims to show a case study for a new brake family to be used in city bus application where the fleets are looking for better, safety, performance and low lining wear reduce the to increase the maintenance time.

In engineering development, simulation methods are frequently used to perform thermal and mechanical stress components analysis. In brake systems, where the components are exposed to mechanical and thermal loads, the numerical analysis is very helpful. Once a numerical model for brake assembly is available, it will be possible to understand the effects of successive brake applications on the temperature distribution in drum brake's friction materials. This is a fundamental aspect to determine, for instance, the thermal stress distribution which is related to the warming and cooling of the brakes. In this work, an analytical solution to calculate stabilized temperature was used to establish a heat flux through a pneumatic S cam drum brake's friction material applied to a numerical model in a finite element analysis.

Strength and durability of commercial vehicle structure is of prime importance to users while quicker time to market and least material cost are demands of competitive world. This requires assessment not just with simplistic loadcases but robust and accurate predictions closely co-relating real proving ground conditions. This paper demonstrates systematic approach of first road load predictions using MBD model, then stress analysis using FE model and finally life prediction using fatigue solver. MBD model was built using flex body, air suspensions with rigid links and tires with FTire characteristics. Same model ran on various virtual proving grounds and load history at various joints were extracted. Then inertia relief stress analysis with unit loads were carried out in Nastran and output stresses were mapped against load history in fatigue solver.

Reliable sealing solutions are extremely important in commercial vehicle industry because sealing failures can cause vehicle breakdown, damage of equipment or even accident, incurring expenses that are substantially higher than the costs of just replacing the damaged seals. Consequently, new seal designs must be experimentally verified and validated before they can be implemented. In this study, Mooney - Rivlin hyper elastic material model is used to simulate the sealing behavior during dynamic conditions. The seal under study is a large diameter lip seal made of Neoprene® rubber (NBR) A finite element model to study the response of the seal under dynamic conditions was developed. The analysis took into account the mating parts dimensions and the lip seal parameters. Three designs were proposed and verified. The seal design is optimized using non-linear FEA and validated. Results include contact pressure, deflection and strain experienced by the seal during actuation.

The search for better energy efficiency is leading the developments in automotive industry, looking for opportunities to reduce losses, optimizing the design and getting better efficiency of every component. This paper will present a non-linear dynamic study of interaction between commercial vehicle and the environment, considering all the influence of their dynamic characteristics in the fuel consumption. The first step is to analyze all variables that influence the dynamic behavior and then construct a mathematical model based on energy and based on forces (Newton). The interaction between the vehicle and its environment and the response of it will be considered as influent aspects and should be included into vehicle dynamic modeling.

The several problems and bottlenecks faced users public transport users in big cities are a common knowledge. Among them agencies responsible for public transport recognize the lack of centralized control, the under and over supply, the lack of information to users and the non-compliance of scheduled trips. In order to work identified problems improving cities like Recife and São Paulo are testing systems named as embedded technology that integrate the use of GPS, cameras, centralized monitoring among others, retarding a deeper coverage compared to systems previously used. The main objectives are the comfort and safety increase of users and the freight logistics improvement. This paper presents the technologies being tested in Brazil through successful models applied in countries as Spain and Colombia, as well as the scope of bids and proposals for improvement of public transport.