Search Results

In this report, adhesion mechanism between epoxy resin and primer and between primer and Ni platting in Hybrid vehicle (HV) was investigated. Adhesion forces are thought to be a combination of mechanical bond forces (such as anchor effect), chemical bond forces and physical bond forces (such as hydrogen bonding and Van der Waals force). Currently there is insufficient understanding of the adhesion mechanism. In particular, the extent to which the three bond forces contribute to adhesion strength. So the adhesion mechanism of polyimide primers was analyzed using a number of different methods, including transmission electron microscope (TEM) and atomic force microscope (AFM) observation, to determine the contributions of the three bonding forces. Molecular simulation was also used to investigate the relationship between adhesion strength and the molecular structure of the primer.

The ignition delay and combustion characteristics of hydrogen jets in an argon-oxygen atmosphere were investigated to provide fundamental data for operating an argon-circulated hydrogen internal combustion engine. Experiments were conducted in a constant-volume combustion vessel to study the effects of ambient temperature, ambient pressure, oxygen concentration and injection pressure on a pre-burning system. The hydrogen-jet penetration and flame were also investigated based on high-speed shadowgraph images. The experimental results indicated that the ignition delay (τ) increases as the ambient temperature (Ti) decreases, similar to the results obtained in an air atmosphere. The heat-release rate results also exhibited similar trends.

The field of diesel combustion research is producing numerous reports on studies of premixed combustion, which promises simultaneous reduction of both NOx and soot, in order to meet increasingly stringent regulations on harmful emissions from automobiles. However, although premixed combustion can simultaneously reduce both NOx and soot, certain issues have been pointed out, including the fact that it emits greater quantities of unburned HC and CO gases and the fact that it limits the operating range. Furthermore, this combustion method sets the ignition delay longer with the aim of promoting the mixing of fuel and air. This raises issues with the product due to the combustion instability and sensitivity to the uneven fuel properties that are found on the market, the capability of the engine response under transient conditions, the deterioration in combustion noise, and so on.

This study focuses on improvement of the predictive accuracy of empirical engine models using the Model Base Calibration (MBC) method. This research discusses the effects of the number of measurement points on the accuracy of models for different Design of Experiments (DoE) by using a direct-injection 4-cylinder diesel engine. The results show that the predictive accuracy of the models converges on fixed values when the number of measurement points is increased in Latin Hypercube Sampling (LHS) and D-Optimal Design. This is because the probability density distribution of the measurement data has little variation as the number of measurement points increases. Comparing LHS and D-Optimal indicates that D-Optimal displays a higher level of accuracy, it is able to extend the boundary model because of its greater number of measurement points at the boundaries of the boundary model.

For reduction of NOx and soot emission with conventional diesel diffusion combustion, the authors focused on enhancement of the rate of injection (hereafter referred to as RoI) to improve air availability, thus enhancing the fuel distribution and atomization. In order to increase opening ramp of the RoI (hereafter referred to as fast injection rate), a hydraulic circuit was improved and nozzle geometries were optimized to make the greatest use of the advantages of the hydraulic circuit. Two different common rail injectors were prepared for this research. One is a mass production-type injector with piezo actuator that achieved the EURO-V exhaust gas emission standards, and the other is a prototype injector equipped with the new hydraulic circuit. The nozzle needle of the prototype injector is directly actuated by high-pressure fuel from common rail to improve the RoI.

Multiple injections that are necessary to reduce emissions, noise, and vibration of diesel engine have been accomplished by common-rail fuel injection system. Especially a fuel amount of each injection has to be tightly controlled, but actually there is a difference between an actual amount and a target one. Injection period will be determined according to a map in that the relation between injected amount and injection period is stated. But in the case of multiple injections, pressure wave caused by previous injections remain in a common-rail system at the time an injection second or later starts. Therefore, actual amounts injected will be different from target ones. In order to compensate the difference, the method that the influence of pressure wave on fuel amount injected is also investigated and injection period will be corrected is realized in an actual engine control system. Meanwhile, pressure wave propagation in common-rail has been studied.

The potential of high efficiency zero-emission engines fueled by hydrogen, which is regarded as a promising form of energy for the future, is being researched. The argon circulated hydrogen engine [ 1 ] is one system theoretically capable of achieving both high efficiency and zero emissions, and its feasibility for use in vehicles has been studied. Specifically, tests were performed to verify the following issues. It was examined whether stable hydrogen combustion could be achieved under an atmosphere of argon and oxygen, which has a high specific heat ratio, and whether the substantial thermal efficiency improvement effect of the argon working gas could be achieved. An argon circulation system was also studied whereby steam, which is the combustion product of the hydrogen and oxygen emitted from the engine, is separated by condensation to enable the remaining argon to be re-used.

Fundamental investigation is conducted on flow and the spark-ignited combustion process of a high-speed, unsteady hydrogen jet, by experimental and theoretical approaches. Jet development and flame propagation in a constant-volume vessel were visualized by means of the shadowgraph technique. The effects of ignition timing and ignition location on the combustion process were investigated. Furthermore, a numerical simulation was performed by using incompressible-flow type computational fluid dynamics with the k-ε turbulence model and the flamelet concept. The pseudo-nozzle concept is applied to the inlet condition with a large pressure gradient. The flame propagation process is described by reference to the flame area evolution model. The results show that the pressure-history in a vessel and the flame propagation process are successfully described for experimental data. Furthermore, the flame propagation process in a jet is investigated.

Formula One engines, which are the pursuit of the ultimate in performance, tend to be comparatively vulnerable to durability issues. These engines sometimes run under a state of unstable combustion as compensation for improved fuel economy. To cope with these issues, there have been strong demands in the racing field for a technology that will allow constant monitoring and prompt action to be carried out on system malfunctions and failures, as well as unstable combustion. The research program described in this paper deals with an onboard technology for monitoring combustion under all the operational conditions using ionic current measurement. The technology will possibly be applied to engine management and car-to-pit communications via telemetering. The scope of the control it offers includes; detection of misfire and hesitation, detection and management of detonation, and management of lean-burn combustion.

A new simple ULEV system has been developed, using only an underfloor catalytic converter. The new system features a VTEC (variable valve timing and lift mechanism) engine with a newly developed catalyst, a precise air-fuel ratio control for maximizing the catalyst performance and the newly developed low heat capacity exhaust system with the air-gap. These technology have contributed to a reduction in the feed gas, the quick activation of the catalyst and an improvement in the maximum conversion ratio of the catalyst, making it possible to pass the ULEV standard without sacrificing vehicle output power.