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Technical Paper

Development of Diesel Particulate Trap Systems for City Buses

1991-02-01
910138
Diesel particulate trap systems are one of the effective means for the control of particulate emission from diesel vehicles. Hino has been researching and developing various diesel particulate trap systems for city buses. This paper describes two of the systems. One uses a wall flow filter equipped with an electric heater and a sensing device for particulate loading for the purpose of filter regeneration. Another makes use of a special filter named “Cross Flow Filter” with an epoch-making regeneration method called “Reverse Jet Cleaning”, by which it becomes possible to separate the part for particulate burning from the filter. Both systems roughly have come to satisfy the functions of trap systems for city buses, but their durability and reliability for city buses are not yet sufficient.
Technical Paper

Development of Conductible Type Vibration Damping Composite Steel Sheet for Automotive Use

1991-02-01
910294
Vibration Damping Composite Steel Sheets (VDC) have recently been developed as a new material to satisfy the requirements concerning various types of noise and vibration control for various fields such as automobiles, electric appliances and building materials. Requirement for VDC continues to expand, because VDC, consisting of two steel sheets and a layer of visco-elastic synthetic resin, which is sandwiched between the two steel sheets, has an excellent damping capability. However, it is rather difficult to spot weld the VDC, as it has an electrically insulating resin layer. To improve the weldability, metal particle is generally mixed into the resin. For automotive body panels, VDC is required to have not only high vibration damping capability but also superior properties such as weldability, bonding strength and formability. In this study, the effects of metal particle size and volume fraction on these properties have been investigated.
Technical Paper

Application of Heavy Duty Diesel Engine to Future Emission Standards

1991-02-01
910482
Future emission standards for heavy duty diesel engines will require extensive development using an integrated approach. This paper describes the latest results from HINO heavy duty diesel engine combustion research program. Improvement of the NOx/particulate/fuel economy trade off requires fuel injection equipment of Pump Line Nozzle (PLN) System and unit injector with high pressure capability, injection rate control and timing control, and a combustion system matched with high pressure injection. Combustion characteristics (ignition delay, combustion period, heat release curve), fuel consumption, particulate, and exhaust gas emission of each injection system are compared and discussed. The unit injector system has an advantage of lower particulate level, especially dry soot, than the Pump Line Nozzle system. The potential for further improvement through engine modification and aftertreatment is also discussed.
Technical Paper

Hybrid Charging System for Heavy Duty Diesel Engines

1991-02-01
910419
In Japan, the next stage exhaust gas emission registration will be introduced around 1994. In case of heavy duty diesel engines, the level of NOx will be limited to 6.0g/kWh and the limit of particulate will be added to it. Its limit will be 0.7g/kWh. In U.S.A, regulation of particulate was already effective in 1988 and it will be tightened in 1991 and 1994. To pass these regulations, turbocharging with an intercooler is recommended to increase air flow, because reduction of black smoke at high load condition will be achieved by the improvement of combustion process. Also it will reduce negative effects by retard of injection timing that reduce NOx level. Although this improvement will be effective over approximate 1000rpm of engine speed, it will not be effective under 1000rpm because an engine can not get sufficient air flow due to poor performance of a turbocharger at this range. This is still one of unsolved problems at present.
Technical Paper

Nato Durability Test of an Adiabatic Truck Engine

1990-02-01
900621
A previous paper (1)* described the performance improvements which can be obtained by using an “adiabatic” (uncooled) engine for military trucks. The fuel economy improved 16% to 37% (depending upon the duty cycle) and was documented by dynamometer testing and vehicle testing and affirmed by vehicle simulation. The purpose of this paper is to document a NATO cycle 400 hour durability test which was performed on the same model adiabatic engine. The test results showed that the engine has excellent durability, low lubricating oil consumption and minimal deposits.
Technical Paper

Measurement of Unregulated Exhaust Emissions from Heavy Duty Diesel Engines with Mini-Dilution Tunnel

1990-02-01
900643
Many reports on characterization of unregulated exhaust emissions from diesel engines and its measurement methods have been presented, but the number of objective chemical compositions used in those experiments are limited. Those reports have referred to use of a large and expensive full-flow dilution tunnel specified by US EPA, and also to the fact that, in case of a partial-flow dilution tunnel which is called “mini-tunnel”, the use should be limited only to steady state engine operations. The authors reported in SAE Paper 890181 that a multi-tube type mini-dilution tunnel, which was compact and less expensive, had good agreement with the full-flow dilution tunnel required by US FTP for heavy-duty diesel engines, when the regulated exhaust emissions were measured on a heavy-duty diesel engine under steady state and transient operaton conditions.
Technical Paper

Mitsubishi New 12.0-Liter Turbocharged and Intercooled Diesel Engine

1990-09-01
901572
To meet the increasingly strong demand for high-speed transportation, better fuel economy, higher reliability and the social requirements for more strict Japanese regulations against exhaust and noise emissions, Mitsubishi Motors Corporation has recently developed the 6D40T1 in-line 6-cylinder, 12.0-liter turbocharged and intercooled diesel engine for heavy-duty trucks. This engine meets the 1989 Japanese exhaust emission regulations and has an output of 258 kW. To achieve both fuel economy and good drivability, Mitsubishi's original, electronically-controlled fuel injection system was adopted. The so-called prestroke-controlled fuel injection pump is capable of flexible and precise control of both fuel injection rate and timing. The basic structure of the 6D40T1 was designed with high rigidity to permit high cylinder pressures. In addition, to reduce friction and heat losses, a 4-valve design, roller cam followers with needle roller bearings, and shortened exhaust ports were adopted.
Technical Paper

The Design and Development of a New Range of Small Industrial Diesel Engines

1990-09-01
901569
A completely new range of air and water cooled diesel engines have been designed and developed by Lister-Petter Ltd. for the 5 kW to 30 kW industrial engine market. Changes to the Company organisation required to meet the demanding cost and time objectives are described. The design philosophy used for the major components is discussed, highlighting those areas where cost savings were achieved without compromising quality or reliability. Two alternative combustion systems are offered on the water cooled engine range and the paper discusses the merits of direct and indirect injection combustion systems.
Technical Paper

Evaluation of Oxygenated Fuel by Direct Injection Diesel and Direct Fuel Injection Impingement Diffusion Combustion Diesel Engines

1990-09-01
901566
Selected as an alternative diesel fuel based on consideration regarding the relationship between the fuel molecular structure and exhaust emission and criteria as alternative fuels, Dimethylacetal (DMA) was evaluated in both a direct injection (DI) diesel and a Direct Fuel Injection Impingement Diffusion Combustion Diesel (OSKA-D) engines. Since DMA with a 1% commercial-type cetane improver has 53 for the cetane number, no ignition-assist divice such as a spark plug is needed, unlike methanol. According to the DI diesel engine test, the NOx emission for DMA was almost equal to that for hydrocarbon diesel fuel, but smoke for DMA was much lower than that for diesel fuel. The OSKA-D engine test showed that NOx emission for DMA was much lower than that for diesel fuel and smoke emission for DMA was zero under all engine conditions.
Technical Paper

The Microcrystal Structure of Soot Particulates in the Combustion Chamber of Prechamber Type Diesel Engines

1990-09-01
901579
To clarify the microcrystal structure of soot particulate in the combustion chamber, we examined sampling methods which freeze the reaction of sample specimens from the combustion chamber and collected the soot particulates on microgrids. We investigated the microcrystal structure with a high resolution transmission electron microscope. The results were: the particle size distribution and the microcrystal structure of the soot particulates is little different for the cooled freezing method and room temperature sampling. The typical layer plane structure which characterizes graphite carbon is not observed in the exhaust of diesel engines, but some particulates display a somewhat similar layer plane structure. The structure of soot particulate is a turbostratic structure as the electron diffraction patterns show polycrystals. The soot particulates in the combustion chamber is similar to exhaust soot particulates.
Technical Paper

The Interaction of Fuel Spray and Air Swirl in a Diesel Combustion Chamber with Nitrogen Gas Circulation

1990-09-01
901580
A single cylinder engine was modified into a photographic test equipment. A new method-filling and cycling nitrogen gas to the cylinder-was used to keep the fuel in combustion chamber out of firing. Tests were carried out at three fuel injection pressure and three gas swirl rates. The chamber swirl rate was measured by hot-wire anemometer, the fuel spray pictures were taken by a high speed camera. By reference to the experimental results, the spray bevaviers in swiling flow were discussed both in the main injection and the end injection periods.
Technical Paper

New Technology for Powershift Transmissions in Hydrostatik Driven Wheel Excavators and Wheel Loaders

1990-09-01
901555
Hydrostatic drives are winning ever-greater preference in fast-moving construction machines vith speeds approaching 40 km/h and a high proportion of reverse-gear operation. A very important precondition to achieving optimum, effective technical solutions is the cooperation of engine, hydrostatic system, multi-ratio powershift transmissions and axles as a complete drive system. The function and complexity of open and closed-loop control systems are also of major influence. Operation of the vehicle must be made simpler for the driver while improving driving comfort, and the speed with which the drive system responds to the drivers commands must be increased. For this to be achieved, the way in which drive power is utilized under constantly changing operational conditions must involve a high degree of automated functions in addition to the manual commands.
Technical Paper

LDA Measurements of Steady and Unsteady Flow Through the Induction System of a Heavy Duty Diesel Engine

1990-09-01
901576
LDA technique was used to investigate valve exit flow and in-cylinder flow generated by a directed intake port of a heavy duty Diesel engine under steady and unsteady conditions. The results obtained under both steady and unsteady show the flow patterns is very sensitive to the valve lift with this type of intake port. At small valve lift, flow profile around the valve periphery is relatively uniform, the corresponding in-cylinder flow is characteristic of double vortex. With valve lift increasing, the separating region appears near the valve seat in part of the valve periphery, therefore the flow pattern begins to depend on the position around the valve periphery. As a result, the valve exit flow is almost along the elongation of intake port at the maximum lift, the corresponding in-cylinder flow behaves as a solid body of rotation. The motion of valve seems to have little effects on the valve exit flow pattern.
Technical Paper

Comparison of Analytical and Experimental Investigations of a Hydraulic Multi-Circuit Sequential Apportioning System

1990-09-01
901553
In conventional hydraulic systems, a fixed or variable displacement pump is used to supply a number of separate branches of a circuit, each with potentially different flow rate and pressure requirements which can vary widely with time. Conventional approaches to distributing the flow to the individual branches generally involve valves controlling the flow to each individual branch. This can lead to significant energy losses from valve throttling, depending upon the actual flow and pressure requirements of each part of the circuit. In the system discussed in this paper, the entire output of the pump is quickly and sequentially directed to each individual branch of the circuit. The average speed of the actuator is controlled by the proportion of time that the pump flow is being directed to that branch. A small accumulator is incorporated in each branch of the circuit to smooth the velocity of the actuator.
Technical Paper

Chemical Flow Control System for Injection-Type Sprayers

1990-09-01
901562
Two peristaltic pumps were tested to determine their accuracies in metering three liquid herbicides for injection-type sprayers. To maintain acceptable chemical application accuracy from either pump, recalibration is necessary if the formulation or its temperature changes. An experimental thermal flowmeter was developed and evaluated along with turbine and piston flowmeters. The piston flowmeter had the best linearity and smallest time constant. A system to control the flow rate of the injected chemical is proposed and was simulated to determine its dynamic response. The proposed chemical metering system, coupled with plumbing systems of sprayers used by private and commercial applicators, were simulated to predict chemical application accuracies.
Technical Paper

Numerical Study for Free-Stream Turbulence Effects on a Single Droplet Vaporization

1990-09-01
901607
This investigation reports on the study of the ambient turbulent effects on the droplet vaporization in the fuel spray combustion. For tractability, this discussion considers a single droplet in an infinite turbulent flow. In this numerical study, the low-Reynolds-number version of k- ε turbulence model was used to represent the turbulence effects. The set of two-dimensional conservation equations which describe the transport phenomena in turbulent flow using the mean flow quantities including the droplet internal laminar motion, are solved numerically with the finite difference procedure of Patankar(SIMPLER). The evaluation of the computational model is provided by two limiting cases: turbulent flow over the solid sphere and the laminar flow over a liquid drop. The results show that the turbulence effects are noticeable for the vaporization at high turbulence intensity (10-50%) which is encountered in a typical spray.
Technical Paper

A Visualization of Spray of Gasoline Injection

1990-09-01
901606
The good relationship between the spray condition in the intake manifold and the combustion characteristics is required. Firstly by this report it was tried the visualization and observation of spray of gasoline injection. It was mainly photographed when injection just began and the spray impinged on a intake valve. The photographs of fuel spray were taken by a image converter type high speed camera. The characteristics of the fuel spray injected in early injection period is influenced with fuel pressure and flow rate of fuel. The atomizing phenomenon of tip fuel of spray could be visualized. The atomizing process in early injection period are differ from that in stady-state spray. And the picture of spray at impingement on the intake valve was shown too. The atomizing condition on the valve surface could be observed visually.
Technical Paper

NIIGATA Ultra Lean Burn SI Gas Engines -Achieving High Efficiency and Low NOx Emission-

1990-09-01
901608
The demand for gas engines running on natural gas and sewage gas has been increasing in recent years as the key of the cogeneration systems which are now being put into commercial use. At the same time, the regulations aimed at reducing air pollution from exhaust gases are becoming more and more stringent in line with the public interest in environmental protection. In response to these demands, the authors have developed the mediumsized, medium-speed gas engines “26HXG” series. The developed engine realizes a very low NOx emission and high efficiency by an Ultra Lean Burn with an excess air ratio exceeding 2.0. This Ultra Lean Burn has been realized by means of a pre-chamber combustion system and a lot of efforts for optimizing design parameters. As a result of the optimization of the design parameters, a low NOx emission of 200 ppm in O2 0% equivalent together with a high thermal efficiency as high as 38 %, which is competitive to the diesel engines, has been achieved.
Technical Paper

Exploratory Development of Low NOx and High Combustion Load Combustor

1990-09-01
901604
A low emission and high combustion load combustor is developed. The combustor reduces both NOx and unburnt fractions using rich-lean staged combustion. NOx is suppressed by fuel-rich combustion in the primary combustion chamber. Unburnt fraction is oxidized by the transition from rich to lean combustion. To avoid NOx formation, residence time nearby stoichiometry is shortened. NOx is less than 24.8 ppm(16 % O2 equivalence) or 2.26 g/kg throughout the experiments. Combustion efficiency is high regardless of the wide operating range. Specific combustion load is up to 33.6 MW/m3 without excessive NOx emission under atmospheric air condition.
Technical Paper

Studies on Combustion and Exhaust Emissions in a High Speed DI Diesel Engine

1990-09-01
901614
Cylinder pressures at several locations and the radiant heat emission were measured simultaneously in order to better understand the combustion behavior in the combustion chamber of a high speed DI diesel engine. The radiant measurements utilized an optical fiber thermometer (OFT) with a light pipe sensor. The exhaust emissions of NOx, smoke and particulates were also measured. The formation of NOx and soot and the soot burn-up processes were analyzed applying an in-cylinder two-zone model. The results were compared with the experiment. It was confirmed that diffusion burning stage started close to the first peak of the heat release rate curve. The OFT output was closely related to the diffusion combustion process. The measured exhaust smoke correlated well with the cumulative diffusion combustion quantity. The dry soot in the particulate emission also correlated well with the Bosch smoke density except for the cases of high sulfur fuel and water-emulsified fuel.
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