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Compacted Graphite Iron (CGI) has been recognized for years as a unique material possessing a fortunate combination of properties intermediate between gray iron and ductile iron. This material, for reasons outlined in this paper, is ideal for cylinder blocks, heads and other cast iron components for diesel engines. It makes possible casting weight savings of up to 1/3 and/or increased power output. This paper will outline reasons why this is now possible, whereas it has seldom been applied in volume production heretofore. Physical and mechanical properties of CGI, which provide the opportunity for weight reduction and increased power, are discussed. Currently, most diesel engine cylinder blocks, heads, liners and many other castings are produced from gray iron, which requires relatively heavy sections to provide the strength, stiffness and durability necessary for commercial application.

Starting from the real vehicle working conditions and taking that engine works at the optimum economic line as a foundation, this paper gives the power transmissive principle of hybrid vehicle with energy storage flywheel working in process of accelerating, uniformly running and braking, derives the relationship of the ratio and time in continuously - variable transmission(CVT) under working conditions of adjusting engine load, recovering and releasing energy etc., and provides the theoretic foundation for transmission system of flywheel energy storage vehicle to realize optimum economic control.

Many design philosophies have been used to design engine mount systems. One is to place the stiffness roll axis coincidental to the torque axis (crankshaft), to produce pure roll under static torque. Another is to focus the mount system to align with the inertial roll axis and uncouple dynamic roll. Recent trends have been to abandon mount system focusing as a criterion, in favor of controlling the six natural frequencies of the powertrain on the mount system. This paper discusses a technique to focus the mounts to uncouple the dynamic matrix, as much as possible within design constraints, while also maintaining control of the powertrain rigid body natural frequencies. Using engine mount system focusing to uncouple the dynamic matrix reduced lateral shake in an experimental vehicle. This reduction in vehicle shake was substantiated by total vehicle system models, experimental measurement, and subjective evaluation.

Technologies and incremental costs for meeting the proposed 2004 US emissions standards for heavy-duty diesel engines are discussed in this paper. Manufacturers will most likely use a combination of technologies including reoptimized combustion chambers, fuel systems, air handling systems, electronic controls and aftertreatment. First year production incremental costs are estimated to range from between $257 and $467 to meet the new standards.

An experimental study to determine the impact of turbocharger outlet conditions, namely boost pressure and temperature, on charge air cooler durability was conducted. A charge air cooler, locally instrumented with strain gauges and thermocouples, was installed in a vehicle and tested in a controlled wind tunnel environment at conditions which produced different amounts of peak boost pressure and turbocharger outlet temperature. Findings suggest that elevated turbocharger outlet conditions should be approached with caution and that charge air coolers for such applications should include appropriate design features.

Protection of the Earth's environment by means of energy saving and cleaning up of air pollution on a global scale is one of the most important subjects in the world today. Because of this, the requirements for better fuel economy and cleaner exhaust emissions of internal combustion engines have been getting stronger, and, in particular, simultaneous reduction in nitrogen oxides (NOx) and particulate matter (PM) from heavy-duty diesel engines (HDDEs) without degrading fuel economy has become a major subject. Mitsubishi Motors Corporation (MM) has been selling diesel-powered heavy-duty trucks in the U.S. market since 1985 and has agressively carried out development work for meeting the 1991 model year exhaust emission standards.

By means of computer simulation, the potential of a Band Variable-Inertia Flywheel (BVIF) as an energy storage device for a diesel engine city bus is evaluated. Replacing both a fixed-inertia flywheel (FIF) and a continuously variable transmission (CVT), the BVIF is capable of accelerating a vehicle from rest to a nearly-constant speed, while recovering part of the kinetic energy normally dissipated through braking of the vehicle. The results are compared with that of conventionally-powered bus. A fuel saving of up to 30 percent is shown with the BVIF-integrated system. The regenerative braking system reduces brake wear by a factor of five in comparison with the conventional vehicle.

There is paucity of literature on temperature generation in the reciprocating contacts. The objective of this paper is to demonstrate development of closed form solution for temperature rise at the non-lubricated piston ring/bore interface of the oil-less /oil-free air brake compressor. The solution will depend on parameters of reciprocating motion of the piston, gas load, piston ring geometry and thermophysical properties of the ring and bore material. The problem is reduced to solving the three-dimensional diffusion equation for a rectangular source of heat involved in a reciprocating motion. The solution is presented in an integral form. The temperature instabilities typical for a line source of heat are avoided by using a rectangular source of heat. The final results are obtained using numerical integration. Various cases of practical interest such as fast and slowly moving piston, long and short piston strokes are considered using a computer program.

Mobility method is used to analyze the steady-state performance of crankshaft and connecting rod bearings which are subjected to loads whose magnitude and direction both vary in time. The steady-state characteristics include journal center orbit, minimum film thickness, maximum film pressure, effective temperature, flow through the bearing, etc. To extract the stiffness and damping coefficients over the load cycle, linear analysis method based on a short-bearing approximation is employed. In addition, the oil flow through the main and connecting rod bearings is investigated. Sufficient lubrication conditions for these bearings are discussed. This combined analysis is supported by numerical simulations. The case studies are based on AlliedSignal's two-cylinder truck air brake compressor, TU-FLO 550, which illustrate the entire approach.

Thermal barrier coatings (TBCs) have been employed for ten years in all types of diesel engines. TBCs have been used to reduce corrosion of pistons and valves, improve fuel efficiency, reduce pollution, allow use of lower quality fuels, improve cost start capability, reduce maintenance costs, improve power and improve lube oil life. Recently much interest has been demonstrated by transit operators in TBCs for pollution control and fuel economy results. A summary of the experience to date, current bus-related activities and advancements in thermal barrier coatings will be discussed. Diesel TBCs (thermal barrier coatings) are plasma-applied ceramic coatings which insulate combustion components such as pistons, valves and fire decks from thermal transmission and shock. Similar coatings have been effectively used in the aerospace industry for many decades.

The city buses start and stop frequently, therefore significant amount of kinetic energy is wasted on friction plates. In order to retrieve this amount of energy, various feasible and efficient energy storage systems have been suggested by researchers to reuse the energy to improve the efficiency of the city bus. Due to small size, high energy density, cleanliness and easiness to absorb/reuse the energy, the storage system of flywheel is hopeful to be coming into wide use. In this paper, a dynamic model is analyzed to study the characteristics of the system using time series. Finally, comparison between simulation and experiment is given.

Chrysler Corporation has developed an 8.0-liter engine for light truck applications. Numerous features combine to produce the highest power and torque ratings of any gasoline-fueled light truck engine currently available while also providing commensurate durability. These features include: a deep-skirt ten-cylinder 90° “V” block, a Helmholtz resonator intake manifold that enhances both low and mid-range torque, light die cast all-aluminum pistons for low vibration, a unique firing order for smooth operation, a “Y” block configuration for strength and durability, a heavy duty truck-type thermostat to control warm up, and a direct ignition system.

During recent years there has been a continuing increase in the demands for higher braking performance of commercial vehicle engines. Mercedes-Benz had introduced the engine brake with continuously open decompression valve (‘Konstantdrossel’) into series production in 1989 as an option (1). A further increase of braking power was to be achieved while retaining the additional decompression valve in the cylinder head. For this, the decompression valve was no longer kept open during the whole working cycle (continuously open decompression valve), but only for a short period from just before compression TDC to about 90...120° crank angle after compression TDC (pulsed decompression valve). The hydraulic actuating system which opens and closes the decompression valves was developed in cooperation with Mannesmann-Rexroth GmbH, Lohr, Germany. The engine braking performance attainable with this system is shown in comparison to other known engine braking systems.

Modern commercial vehicle engines are equipped with turbocharging and intercooling. This results in low emissions and fuel consumption. In the lower speed and load range and under transient conditions, these engines have disadvantages, as the fuel injection rate has to be limited to avoid excessive smoke emission. Also, the engine braking performance of highly charged, small displacement engines is also lower than that of large displacement engines. Mercedes-Benz decided to develop a combination of turbocharger and mechanical supercharger. In the lower speed range higher torque levels are possible and maximum torque is available without any lag especially in the transient mode with low smoke emission and fuel consumption. Vehicle performance during acceleration can be improved by up to 30%. During engine braking operation, the mechanical supercharger is activated throughout the whole engine speed range which results in a distinctive increase in braking power.

To reduce diesel engine noise that is induced mainly by main bearing impact forces, two types of low noise concepts of basic crankcase structures were studied. One is the “Isolated Skirt Type”, which has the feature to suppress vibrations of engine surface by separating the crankcase skirt from the main bearing caps. The other is the “Bed Plate Type”, which embodies the feature to suppress vibrations by stiffening the lower part of crankcase by adopting a bed plate design. Dynamic characteristics of both prototypes were investigated by means of experimental modal testings such as double pulse laser holography system and impulsive hydraulic excitation test rig which simulates the exciting force of combustion gas pressure in cylinder. As the result of many experimental tests, it was concluded that the “Bed Plate Type” was advantageous over the “Isolated Skirt Type” in terms of engine noise reduction.

Air applied, mechanically held (AAMH) air brake systems or lock actuators as they are sometimes called in Europe, have been around for a long time but they were not well known nor have past designs been very successful. Now a new design in a piston configuration and an internal wedge locking mechanism overcomes previous problems with this type of system and offers operating advantages over the common spring brake system. This paper examines the operation of the AAMH system.

In this paper,the flywheel is considered to be linear elastic composition in accordance with its operating characteristic, mechanical and mathematical model are presented,the finite element method is employed to carry out the numerical analysis of steady and unsteady stresses within the high speed flywheel in the regenerative braking system of a city bus,and these provide the basis foŕ its structural modification and further rational design.

One of the main factors of the drum brake performance and quality is the accuracy of “S” profiles of the cam shafts. To reduce cost, most axle and brake manufacturers use cam shafts with forged “S” cams, in some cases decreasing the accuracy of “S” profile, brake performance, and quality as compared to a machined “S” profile option. Today's highly competitive market, especially the bus market, requires the highest possible brake performance at reduced cost. This paper shows how to meet both requirements for cam shaft manufacturing, high “S” profile accuracy and low machining cost, at the same time.

A new, systematic approach to the design-evaluation-test product development cycle is described wherein the vehicle design and simulation environments are integrated. This methodology is applied to brake mechanical design and material selection. Time-domain computations within a vehicle dynamic simulation environment account for brake and lining geometry and material properties, actuator properties, and temperature effects. Two examples illustrate the utility of this approach by examining: the effect of varying hydraulic cylinder diameter on passing federally mandated stopping distance tests, and the effect of S-cam actuator adjustment on the performance of air brakes on a tractor-trailer. The simulation results are compared with experimental vehicle stopping distance tests to assess the validity of the simulations.

The primary objective of this paper is to develop a model that accurately represents the dynamics of air flowing through the components of a pneumatic system configuration, which is common in many heavy duty vehicle applications, that eventually translates into braking force. This objective is met using the dynamic compressible airflow equations, which describe flow through an orifice. These equations are coordinated to describe the directional motion of dynamic airflow as commanded by the driver at the foot-pedal and as modified downstream by a modulator to facilitate ABS activity. The solenoid actuated relay valve also includes the motion dynamics of a piston in the existence of hysteresis and coulomb friction type built-in non-smooth nonlinearities. The adoption of an isentropic process, as opposed to the more general case of polytropic behavior, is experimentally determined to suffice for accuracy while yielding significant mathematical convenience.