Tokuta Inoue

Development of the Toyota Lean Combustion System

The lean combustion of an SI engine has been recognized as one of the most promising methods for further improvement of fuel economy. There has been, however, difficulty in extending the lean misfire limit enough to realize no-x emission levels below the mandatory level and still keep satisfactory driveability. A simulation study has been carried out to search for the possibility of getting better fuel economy under the constraints of no-x emission and driveability. To realize the optimum calibration, the lean misfire limit has been extended by the introduction of (1) high swirl and high combustion chamber turbulence through the use of a helical port with an unique swirl control valve, (2) a newly developed ZrO2 lean mixture sensor and (3) the multi-point fuel injection with sophisticated control. A very good fuel economy level of 17.0 km/l (Japanese 10 mode) has been accomplished while still meeting the NO-X emission cycle regulation of 0.25 g/km. This paper describes the system and its components, the results of the simulation and the experiments on the effects of each component. (Author/TRRL)

An adaptive fuel injection control with internal model in automotive engines

An adaptive fuel-injection control system has been developed for automotive engines. It uses a new air-fuel (A/F) ratio sensor to sense the wide A/F range, and consists of three subsystems based on a fuel behavior model: an inverse system (IS), a model following compensator (MFC), and an estimator of model parameters (EMP). The EMP estimates the parameters of the fuel behavior model during idling and adjusts the IS and MFC. This system allows accurate control of the A/F ratio during acceleration or deceleration, even when the engine coolant temperature conditions and/or fuel compositions vary.<<ETX>>

Nitrogen CARS thermometry for a study of temperature profiles through flame fronts

Abstract Using coherent anti-Stokes Raman spectroscopy (CARS), we have performed detailed axial and radial temperature surveys in a premixed methane-air flame at atmospheric pressure with a special emphasis on measurements of temperature profiles through thin flame fronts. The temperature is inferred from N 2 CARS spectra. The thickness of flame fronts for flames with a stoichiometric mixture is about 700 μm, while it broadens considerably in a fuel rich flame. The spatial resolution for measuring the temperature profile is about 100 μm.

The Effects of ‘Inclination Angle of Swirl Axis’ on Turbulence Characteristics in a 4-Valve Lean-Burn Engine with SCV

It has been demonstrated that the in-cylinder turbulence of a 4 valve engine with a swirl control valve (SCV) is enhanced by inclined swirl. This paper examines the effects on turbulence of varying swirl inclination angle defied as the inverse tangent of the vertical component of total angular momentum divided by the horizontal component. Experiments were conducted on a 4-valve single cylinder engine with SCV using a backward-scatter LDV and BSA (Bust Spectrum Analyzer). The results show that although total angular momentum is greatest with horizontal swirl, turbulence intensity measured in the center of the combustion chamber attains a peak value when the swirl inclination angle is between 30 and 45 degrees from the cylinder axis under the same flow rate.

Effects of Helical Port with Swirl Control Valve on the Combustion and Performance of S. I. Engine

A helical port with swirl control valve (SCV) has been developed to satisfy two inconsistent requirements of achieving sufficient swirl generation to improve the combustion and still maintaining high volumetric efficiency. Their effects on combustion were confirmed in a single cylinder engine using high speed flame photography and cylinder pressure diagram analysis which has demonstrated faster combustion. As a result of a hot wire anemometer study, the differences in gas motion were clarified between two helical port with and without SCV, and more active movement of the center of swirl was measured in the case of helical port with SCV which suggests generation of higher turbulence in the cylinder.

Development of Methanol Lean Burn System

A methanol fueled, lean burn system has been developed to improve both specific fuel consumption and NOx emissions. A 1.6L four-cylinder engine with increased compression ratio has been used to develop this system. Three major components of the Toyota Lean Combustion System (T-LCS) has been applied: (1) A helical port with a swirl control valve (2) A lean mixture sensor (3) Timed, multi-point fuel injection. A 2250 lb. Inertia Weight test vehicle has been fitted with this engine, and fuel system materials have been modified. This methanol, lean burn system has improved the fuel economy by about 12%, still satisfying the 1986 emission standards of the U.S.A. and Japan. Aldehyde emissions have also been evaluated.

Regenration Process of Ceramic Foam Diesel-Particulate Traps

Periodic regeneration of the diesel particulate trap is essential to maintain the collection efficiency and exhaust gas back pressure at acceptable levels. The objectives of this study are to describe the phenomenology of ceramic foam filter regeneration process and to present its mathematical model. Further simulation study is carried out to estimate the effects of various factors including fuel additive on the ignition and the filter bed temperature and to investigate conditions of excessive temperature which could result in filter destruction. The model is based on the assumption that the regeneration process is composed of two steps. The first step is the additional heat supply from the external energy source, and the second step is the spontaneous combustion propagation. The results from the analytical model agreed very well with the experimental results. Additional energy is required above normal engine operating conditions to initiate the incineration under lower exhaust gas temperature. Regeneration must be carried out within a narrow range of particulate loading to avoid the melting of the filter material. The effects of fuel additives have been estimated by using the mathematical simulation.

Lean combustion characteristics of locally stratified charge mixture: Basic studies of in-vessel combustion ignited by laser

Abstract In order to study the trade-off between improved lean combustion and reduced NO x emissions under a locally stratified charge mixture, this paper examines the effects of the rich mixture volume on combustion duration and the NO x emissions under the same total equivalence ratio in a combustion vessel. The rich methane-air mixture in a soap bubble was ignited at the center of the bubble by a pulsed YAG laser. As a result, it was found that the magnitude of the NO x emissions does not increase as the rich mixture volume increases up to a critical volume, but the combustion duration at that time shortens remarkably. The same tendency was also obtained by means of computer simulation using a 4-cylinder lean burn engine.

Direct synthesis of middle isoparaffins from synthesis gas

Branched paraffins with 4 to 7 carbon number shows high octane number as well as high reactivity for steam reforming, which suggest the binary fuel for both internal combustion engine and fuel cell engine as well. It wastried to make iso-paraffin rich hydrocarbons by Fischer-Tropsch Synthesis (F-T-S) over Co/SiO 2 catalyst. The basic concept is to secondarily isomerize or hydrocrack the F-T-S products. Small amount of added zeolite to Co/SiO 2 catalyst, enhanced the formation of C 4 -C 1 0 isoparaffins while suppressing the formation of longer hydrocarbons probably because of the selective cracking of higher hydrocarbons by zeolite. The three-component catalyst (Co/SiO 2 -Pd/SiO 2 -ZSM-5) promoted the formation of paraffins, whereas the yield of isomerized products was not high enugh. For 2-steps reaction, the first step catalyst is the zeolite modified Co/SiO 2 catalyst and the second catalyst is Pd/SiO 2 +ZMS-5 catalyst where additional hydrogen was added. The selectivity of isoparaffins was markedly promoted and the molecular weight of the product decread while the syngas conversion was kept constant. The hydrocracking of n-octane (which is the model compound of FTS reaction) over hybrid catalyst composed of Pd/SiO 2 -zeolite and showed high and stable activity giving iso-paraffin rich hydrocarbons. The isomerization was favored for Pd rich catalyst. The role of Pd is the port hole of hydrogen spill-over to zeolite.

Deposition of a-Si Films Using Silane Molecular Beams Excited by Heated Wire and ArF Laser

Amorphous silicon films were deposited by using silane molecular beams excited either by ArF laser beams or heated tungsten wires. Reaction mechanisms are discussed on the basis of the dependence of deposition rates on substrate temperature and, in the case of the heated-wire method, on wire temperature.