Search Results

A numerical modeling technique is proposed for computer simulations of high speed valve train dynamics. The dynamic terms in the valve spring reaction forces are calculated using linear vibration theory for given kinematic valve motions. Because the spring dynamics are analyzed before the time stepping integration, spring surge phenomena can be included without using additional computer time. Consequently, valve train dynamics can be simulated very quickly without noticeable errors in accuracy. The experimental results prove the computer model developed here is accurate and also computationally efficient.

In 1990, Roy Douglas developed an analytical method to calculate the global air-to-fuel ratio of a two-stroke engine from exhaust gas emissions. While this method has considerable application to two-stroke engines, it does not permit the calculation of air-to-fuel ratios for oxygenated fuels. This study proposed modifications to the Roy Douglas method such that it can be applied to oxygenated fuels. The ISO #16183 standard, the modified Spindt method, and the Brettschneider method were used to evaluate the modifications to the Roy Douglas method. In addition, a trapped air-to-fuel ratio, appropriate for two-stroke engines, was also modified to incorporate oxygenated fuels. To validate the modified calculation method, tests were performed using a two-stroke carbureted and two-stroke direct injected marine outboard engine over a five-mode marine test cycle running indolene and low level blends of ethanol and iso-butanol fuels.

Motorcycle usage continues to expand globally. Motorcycles use various fuels in different countries and regions, and it is required that they comply with emissions and fuel consumption regulations as specified in UN-GTR No.2 (WMTC). In general, a motorcycle engine has a large bore diameter and a high compression ratio due to demands of high performance. Poor fuel quality may cause damage to the engine, mainly by knocking. Knock control systems utilizing high-frequency vibration detection strategies like knock sensors, which are equipped on several sport-touring motorcycles, are not used widely for reasons of complex construction and high cost. This research aims to develop a new concept of combustion control for common motorcycle as an alternative.

Clothing accounts for a surprisingly large quantity of resupply and waste on the International Space Station (ISS), of the order of 14% of the equivalent system mass (ESM). Efforts are underway in the ISS program to reduce this, but much greater changes are likely to be possible and justifiable for long duration missions beyond low Earth orbit (LEO). Two approaches are being assessed for long duration missions: to reduce the mass of the wardrobe through use of lighter fabrics, and to clean clothing on board for reuse. Through good design including use of modern fabrics, a lighter weight wardrobe is expected to be feasible. Collateral benefits should include greater user comfort and reduced lint generation. A wide variety of approaches to cleaning is possible. The initial evaluation was made based on a terrestrial water-based washer and dryer system, as this represents the greatest experience base.

These last years, much of researches were carried out to find the appropriate substitution fuel to the fossil fuels. The use of biofuel prepared from non-edible vegetable oils are becoming a promising source to produce a fuel for diesel engine, commonly referred to as “biodiesel”. Considering the high oil extraction yield (around 40%) and the great quantity of pistacia lentiscus (PL) trees available in arid and semi-arid areas of Mediterranean countries, it is selected in the present work to study the biodiesel prepared from PL oil. PL biodiesel is obtained by converting PL seed oil with a single-step homogenous alkali catalyzed transesterification process. PL biodiesel characterization, according to the standard methods, shows that the physicochemical properties are comparable to those of conventional diesel fuel. In a second part, a single cylinder air-cooled, DI diesel engine is used to test PL biodiesel at 1500 rpm under various engine load conditions.

In racing world regardless of two-wheeled vehicle (motorcycle) or four-wheeled vehicle, vehicle setting is performed in accordance with various race conditions. From the age of carburetor till even now ECU is used, vehicle setting executes as well and plays an important role. Changeover to electronic control makes vehicle control more precise; meanwhile, vehicle control technique to become complicated is occurring every day. Therefore, whenever a new competition vehicle is developed, tool required for vehicle setting is also necessary to be updated according to vehicle control technique implemented. Setting-method till now is that, all information required for vehicle setting is packaged in tool, thereby tool and vehicle have always been a combination of 1-to-1. Consequently, in manufacturer's vehicle development, tool development / update becomes a burden and leads to increment of development costs.

Knock is a major technological constriction of natural gas spark ignition engines. Nowadays, it is widely accepted that knock is due to auto-ignition in the end gas region. Knock can occur for different reasons, which could be related to the engine itself (design and settings) or to the gas composition (or the gas quality). In a previous study the effect of engine settings on knock in a C.F.R. SI engine fuelled by pure methane was established by using a knock indicator, based on the evaluation of the energy of end gases. The paper deals with knock limit prediction from natural gas quality in a C.F.R. engine. A 2-zone thermodynamic model was developed in order to predict knocking conditions by evaluating a knock indicator. The model relies on some standard assumptions. Ignition delay was expressed as a function of engine settings, and a physical correlation for the heat release rate model was used.

This paper introduces a novel personal rapid transit (PRT) system and further describes the process of designing and optimizing the suspension system for the prototype vehicle. The objective of the prototype development is to build a small, low-cost, lightweight, and comfortable vehicle. The current build of the vehicle lacks enough roll stiffness or a smooth ride. As such, a complete redesign of the suspension system for the next generation of prototypes is desired. The Short-Long Arm (SLA) double wishbone suspension with an outboard coil is the design of choice for the new prototype. To evaluate the ride and safety, a quarter-car model is evaluated for suspension travel, body acceleration, and dynamic wheel load over a pseudo-random road profile. The results from these models show a comparison between the two prototype vehicles in relation to their ride comfort and safety.

The Drive By Wire (hereafter referred to as DBW) system is the electronically throttle control system. It controls a throttle valve in order to aim at a suitable throttle position according to an engine operating condition and a demand of driver or rider. This system is basically composed of a throttle body with driving motor, an Accelerator Position Sensor (hereafter referred to as APS), and an Electronic Control Unit (hereafter referred to as ECU). The DBW system is spreading to motorcycle field as replacement of existing mechanical intake control system. This is because there are some advantages as the following especially in the large displacement model: capability for installation of several functions, flexibility in adaptation to recent environmental regulations, and effect on reduction of system cost, etc. In general, the motorcycle has some unique features compared with the automobile. Among them, important features for the DBW system are following three points.

A new power control unit (PCU) has been developed for a Honda small hybrid vehicle with a two-motor hybrid system launched in 2020. For small hybrid vehicles, downsizing and reducing costs of hybrid systems are major challenges. As such, there were emphatic requirements for the newly developed PCU to be small and affordable. To satisfy these requirements for the PCU, new technologies and components have been introduced such as an all-in-one type intelligent power module (IPM) with integrated functions and reverse conducting IGBT (RC-IGBT), a new control sequence for voltage control unit (VCU), and revised PCU packaging to improve cooling performance. The new IPM has a printed-circuit board (PCB) equipped with an electric control unit (ECU) and gate drive circuits, 7 current sensors, and a power module with RC-IGBTs. This functional integration led to a reduction in the number of main electrical PCU assembly components from 9 in the previous PCU to 2 in the new PCU.

Numerical simulation is a useful and a cost-effective tool for engine cycle prediction. In the present study, a dual Wiebe function is used to approximate the heat release rate in a DI, naturally aspirated diesel engine fuelled with eucalyptus biodiesel/diesel fuel blends and operated at various engine loads. This correlation is fitted to the experimental heat release rate at various operating conditions (fuel nature and engine load) using a least squares regression to find the unknown parameters. The main objective of this study is to propose a model to predict the Wiebe function parameters for more general operating conditions, not only those experimentally tested. For this purpose, an artificial neural network (ANN) is developed on the basis of the experimental data. Engine load and eucalyptus biodiesel/diesel fuel blend are the input layer, while the six parameters of the dual Wiebe function are the output layer.

The performance of Gasoline Direct Injection (GDI) engines is governed by multiple physical processes such as the internal nozzle flow and the mixing of the liquid stream with the gaseous ambient environment. A detailed knowledge of these processes even for complex injectors is very important for improving the design and performance of combustion engines all the way to pollutant formation and emissions. However, many processes are still not completely understood, which is partly caused by their restricted experimental accessibility. Thus, high-fidelity simulations can be helpful to obtain further understanding of GDI injectors. In this work, advanced simulation and experimental methods are combined in order to study the spray characteristics of two different 3-hole GDI injectors.

This paper presents a cohesive set of engine-in-the-loop (EIL) studies examining the use of hierarchical model-predictive control for fuel consumption minimization in a class-8 heavy-duty truck intended to be equipped with Level-1 connectivity/automation. This work is motivated by the potential of connected/automated vehicle technologies to reduce fuel consumption in both urban/suburban and highway scenarios. The authors begin by presenting a hierarchical model-predictive control scheme that optimizes multiple chassis and powertrain functionalities for fuel consumption. These functionalities include: vehicle routing, arrival/departure at signalized intersections, speed trajectory optimization, platooning, predictive optimal gear shifting, and engine demand torque shaping. The primary optimization goal is to minimize fuel consumption, but the hierarchical controller explicitly accounts for other key objectives/constraints, including operator comfort and safe inter-vehicle spacing.

The crude oil depletion, as well as aspects related to environmental pollution and global warming has caused researchers to seek alternative fuels. Biogas is one of the most attractive available fuels. It is of great interest both economically and ecologically. However, it faces problems that may compromise its industrial use. The dual-fuel engines have been investigated as a technique for the recovery of these gases and finding solutions to these problems. In the present work, performance and emissions of a direct injection diesel engine were first evaluated in conventional mode and dual fuel mode. The effect of biogas composition, based on methane content, is then examined. Also, dual fuel operation with regard to knock is investigated. The results show that, up to 95% of engine full load, the brake thermal efficiency (BTE) is lower in dual fuel mode. In terms of the specific consumption, although at high load the gap is much less, it is more significant in case of dual fuel mode.

Biologically derived isobutanol, a four carbon alcohol, has an energy density closer to that of gasoline and has potential to increase biofuel quantities beyond the current ethanol blend wall. When blended at 16 vol% (iB16), it has identical energy and oxygen content of 10 vol% ethanol (E10). Engine dynamometer emissions tests were conducted on two open-loop electronic fuel-injected marine outboard engines of both two-stroke and four-stroke designs using indolene certification fuel (non-oxygenated), iB16 and E10 fuels. Total particulate emissions were quantified using Sohxlet extraction to determine the amount of elemental and organic carbon. Data indicates a reduction in overall total particulate matter relative to indolene certification fuel with similar trends between iB16 and E10. Gaseous and PM emissions suggest that iB16, relative to E10, could be promising for increasing the use of renewable fuels in recreational marine engines and fuel systems.

The hybrid electric vehicle is currently changing the automotive market at an impressive rate. While not as highly publicized, the transit bus market is being transformed at an equal rate. As these markets move forward, the school bus market remains largely unchanged. As an unchanged market, there is still the opportunity to optimize a hybrid vehicle platform for school buses. This study begins the modeling process of an existing class C school bus and investigates the potential that both series and parallel hybrids hold to reduce fuel consumption and emissions for a school bus. The primary focus of this study is to investigate the potential benefits of adding an electricity grid interconnection to hybrid electric school buses, allowing them to add to the hybrid potential with a pre-charged battery pack from the electric utility grid. These vehicles are known as plug-in hybrids.

Near-term advances in spark ignition (SI) engine technology (e.g., variable value lift [VVL], gasoline direct injection [GDI], cylinder deactivation, turbo downsizing) for passenger vehicles hold promise of delivering significant fuel savings for vehicles of the immediate future. Similarly, trends in transmissions indicate higher (8-speed, 9-speed) gear numbers, higher spans, and a focus on downspeeding to improve engine efficiency. Dual-clutch transmissions, which exhibit higher efficiency in lower gears, than the traditional automatics, and are being introduced in the light-duty vehicle segment worldwide. Another development requiring low investment and delivering immediate benefits has been the adaptation of start-stop (micro hybrids or idle engine stop technology) technology in vehicles today.

Fuel spray injected by a port injector has significant effects on engine power output and combustion efficiency. For this reason, it is necessary to atomize fuel into fine droplets and accurately supply it without being susceptible to any changes in temperature or negative pressure affected by engine. This document introduces an atomization technique with optimized layout of nozzle holes and drastically reduced pressure loss (energy loss) in the flow under a needle valve seat. It also describes an injector having a short fuel flow path and a small dead volume under the valve seat, which can have good resistance against any changes in temperature and negative pressure.

This paper presents the evolution of a series of connected, automated vehicle technologies from simulation to in-vehicle validation for the purposes of minimizing the fuel usage of a class-8 heavy duty truck. The results reveal that an online, hierarchical model-predictive control scheme, implemented via the use of extended horizon driver advisories for velocity and gear, achieves fuel savings comparable to predictions from software-in-the-loop (SiL) simulations and engine-in-the-loop (EiL) studies that operated with a greater degree of powertrain and chassis automation. The work of this paper builds on prior work that presented in detail this predictive control scheme that successively optimizes vehicle routing, arrival and departure at signalized intersections, speed trajectory planning, platooning, predictive gear shifting, and engine demand torque shaping.

CHP power plants, supplied by natural gas, have a great interest due to more and more stringent environmental regulations. Natural gas has a low C/H ratio resulting in low CO2 emissions in spark ignition engines. For economical reasons, CHP gas engines are normally designed to operate under their optimal settings. Small variations in the composition of the supplied gas can then lead to knock occurrence. In this paper, a preventive knock device is developed for CHP power plants. It is based on the instantaneous measure of the Methane Number (MN) of the supplied gas. The measure is performed through an online MN gas sensor (it measures as well Wobbe index and the calorific value of the supplied gas). Prediction of knock, following the MN of the gas is developed in previous works. Correction of knock is performed through an engine map, established thanks to numerical simulations.