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A new impinging nozzle head attached on a normal injection nozzle was designed for improving the performance and combustion of DI diesel engine. Since the fuel is directly injected to the nozzle head at a very short distance from a spray tip of nozzle in a DI diesel engine, the fuel particles will be improved in spray diffusion and distribution. In the case of a prototype injection nozzle with four orifices, the spray angle from each orifice is narrow and similar to the shape of conifer's leaves. By using of the new designed impinging nozzle head, however, an improved spray angle and distribution of fuel and a better starting performance at very low temperature have been observed.

This report is concerned with the theory and experiment of reducing the exciting force in piston-crank mechanism by the using of an eccentric gear trains during in a non-uniform velocity balancer system. For the experiment, we desinged a special apparatus to measure the exciting force at X and Y directions, and the rolling moment M causing form crankshaft, in an unloaded single-cylinder diesel engine. The obtained results supported our theory, and were compared with that of a conventional engine, too.

This paper is concerned with a new type of non-uniform velocity balancer appling to the single cylinder engine. A conventional balancer rotate in an uniform velocity,while the new one rotate in a non-uniform velocity. A non-uniform velocity rotation is given by the eccentric gear installed balancer shaft. It is recognized that the moderate eccentricity of gear train is existed for reducing the exciting force and its effect is remarkable.

This paper is describes the progress of the development of continuous variable valve timing mechanism by the combination of the three-dimensional cam and the moving rocker arm, and the performance of 4 cylinder gasoline engine with this mechanism. This continuous valve timing mechanism is very concise. Through the trial product's experiment, it proved to be reliable. Furthermore, engine performance demonstrated high torque and low fuel consumption in wide engine speed range.

Several different shaped impinging nozzle heads have been studied. A small impinging nozzle head supported by single stay shows a good spray distribution, and economic fuel consumption under middle engine loads and all engine speeds In a single cylinder DI diesel engine without air swirl Intake system.

This paper is described the performance of VVT using engine cycle simulation software and the verification of compression ignition combustion in practical engine. It was predicted by engine cycle simulation that the control of high temperature EGR by the application of VVT improved thermal efficiency markedly by compression ignition combustion. A trial VVT is applied to an actual engine, and compression ignition combustion is realized.

Fuel injected from multi-hole injector with a small injection angle (100°) is impinged to the multi-impingement-wall head(MIW head), which is located in the center of combustion chamber and is attached to the cylinder head. The fuel is diffused into the piston cavity to form a three-dimensional diffusion spray. The main advantage of diffusion spray is that the effects of the fuel impinging diffusion and the collision between fuel particles can be obtained. Based on the concept of MIW head, the experimental results show that the combustion performance and the fuel consumption have been improved. Besides, the NOx, HC and smoke densities of the exhaust gas of a diesel engine have been reduced.

A three-dimensional diffusing spray using the multi-impingement-wall head (MIW head) has been proposed to form air-fuel mixtures in a simple DI diesel engine. In this paper, effects of the width of the MIW head on spray pattern, distribution and engine performance have been investigated. In the fuel spray and engine performance experiments, an optimal width of MIW head results in the collision of fuel particles to advantageous position in a combustion chamber for obtaining a good fuel spray distribution. The minimum BSFC is almost the same value as that of a single DI diesel engine, the HC and smoke densities are reduced and the NOx density is shown a tendency to some increase under part load and decrease under full load. A relatively slow heat release rate and maximum temperature duration of the MIW head can be obtained by shortening the ignition delay.

The multi-impingement-wall head (MIW head) is designed to be located at the center of combustion chamber and is attached to the cylinder head. In this paper, a new concept of the MIW head has been investigated to obtain a three-dimensional diffusion spray for improving the combustion and performance of a DI diesel engine. Four Types of combustion chambers, the troidal type used in a normal DI diesel engine, and the reentrant types with a projection, with a cutouts, and their combinations (with both projection and cutouts) have been used in the NICS-MH engine experiments. Based on the experimental results of engine performance, it shows that the reentrant type of combustion chamber with a projection and a cutouts has a better fuel consumption and produces lower harmful exhaust gases (HC, NOx and smoke) than those of other NICS-MH engines.

As an effective means of improving engine output, turbocharging has been widely used in engines. However, due to the inherent mismatch of a turbocharger to a reciprocating machine, a turbocharged machine does have some drawbacks,such as the reduction in transient performance, low torque backup, low torque and etc. One solution to these problems is to dynamically vary the size of the turbine stage, reducing the swallowing capacity of the turbine at lower gasflows and increasing the swallowing capacity at high gasflows. A turbocharger fitted with such a turbine is called “Variable Geometry” turbocharger. In general, there are two types of variable nozzle turbocharger. One is the traditional gas turbine approach of using a set of individually pivotable nozzle guide vanes (1) (2), and the other is with axial movable nozzle vanes (3) (4) (5).

An axially movable vane turbocharger has been modified based on the basic aerodynamic design principles, and good performance is obtained. The details of design and engine bench testing results of several vane variations are presented, and the most suitable assembly nozzle with two separate vanes is then developed. These have produced a simple design with a minimum number of the moving parts. Experimental data also show that the new turbocharger efficiently expands the effective torque band and get the low fuel consumption at a wide engine speed range.

This report describes with the performance test of a diesel engine using a new variable scroll type turbocharger (VS turbocharger). The experimental variable scroll is relatively a simple structure in which several scroll pieces are jointed by pins, located inside of exhaust turbine inlet flow passage. The scroll is varied by the control rod according to exhaust flow volume, and as a result, the A/R ratio that effects to the performance of turbocharger is varied. To compare the performances of variable scroll type turbocharger with a conventional turbocharger with waste gate, a test of diesel engine equipped with each was performed. The experimental results show that VS turbocharger increases more than the conventional turbocharger in boost pressure at lower engine speed, and the wide torque range is ensured. Also, the experimental scroll pieces did not showed signs of trouble from heat wear during experimentation ensuring reliability.

A new variable scroll type turbocharger has been developed, which is a kind of variable geometry turbocharger. This paper describes a method for determining the shape of a scroll chamber of a turbine housing of the turbocharger. The basic idea is to vary the flow area using the scroll according to exhaust gas flow. The scroll consists of several scroll pieces joined to form a linked variable structure. The shape of the scroll pieces is decided on the basis of an Archimedes’ curve. The device developed is relatively simple.