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The filtration efficiency of a DPF drops when it suffers a failure such as melting and cracks during regeneration. And then, on-board diagnostics (OBD) device has become needed worldwide to detect a DPF failure. In the development of an OBD soot sensor, evaluation of the sensor demands a portable instrument which can measure the soot concentration for on-board and in-field use. Some of the emission regulations require the in-field emission measurements under normal in-use operation of a vehicle. This study is intended to develop a high sensitivity and high response portable smoke meter for on-board soot measurements and a reference to OBD soot sensors under development. The smoke meter accommodates a 650 nm laser diode, and its principle is based on light extinction in high soot concentration range and backward light scattering for low soot concentration measurement.

Tier 2 Emission standards enacted by the U.S. Environmental Protection Agency (EPA) require substantial emission reductions for new vehicles, including those with diesel engines. The standards are fuel neutral, and all light duty vehicles must eventually meet a fleet averaged emission level of Bin 5. To improve the emission capability for diesel engines, several advanced technologies have been investigated. These technologies include: common rail FIE with multi-injection capability, enhanced cooled EGR system with increased flow capability, variable geometry turbo charger, and a lower compression ratio piston. A new combustion approach using premixed diesel combustion was applied in the low load area for improving NOx and soot emissions significantly in the FTP-75 test cycle. Applying these technologies, engine out NOx was substantially reduced while maintaining similar soot levels.

Control of NOx and PM from diesel engines is a key for enlarging its application in transportation field. To achieve this, many improvements have been done, for instance, the introduction of highly flexible common-rail injection system and cooled EGR system with advanced control strategy. In order to meet more stringent emission regulations in near future, research and development activities have been carried out energetically in the world. In this paper, a low emission combustion strategy is realized by combination of common-rail and cooled EGR. First of all, low soot combustion is approached by optimizing pilot and main injection, in which pilot is controlled to eliminate hot flame. Then, once low soot combustion achieved, higher EGR can be used to reduce NOx.

A new concept of highly efficient and sulfur tolerant NOx reduction catalyst for diesel engines has been demonstrated. This catalyst has a double-layer construction and is composed of Pt and Rh as the precious metals, oxygen storage materials and some other catalytic components. Periodic lean/rich operation similar to the Lean NOx Trap catalyst was found to improve the highly efficient NOx reduction activity in a laboratory reactor test. As a result, this catalyst has the feature of high NOx reduction in a temperature window from 15°C to 35°C, and of high oxidation activity even in a lower temperature condition for HC and CO. Sulfur poisoning characteristics were also evaluated in a laboratory reactor test. The results showed that the proper desulfation procedure with a relatively low temperature environment enabled the stored sulfur to be reomved, and to maintain the NOx reduction efficiency for asignificantly long time period.

A compact, lightweight compression-ignition engine designed for high fuel economy and low emissions was developed by ISUZU for the GM PNGV vehicle. This engine was the key component in the selected parallel hybrid vehicle powertrain for the 80 mpg fuel economy target. The base hardware was derived from a 1.7 Liter, 4-cylinder engine, and a three-cylinder version was created for the PNGV application. To achieve the required high efficiency, the engine used lightweight components thus minimizing weight and friction. To reduce exhaust emissions, electromechanical actuators were used for EGR, intake throttle, and turbocharger. Through careful application of these devices and combustion development, stringent engine out exhaust emission targets were also met.

The newly developed Duramax 6600 V8 Diesel engine has incorporated a lot of the latest technologies to achieve better fuel economy and lower exhaust emissions. It will provide the GMC Sierra and Chevrolet Silverado with a Diesel engine to satisfy a multitude of major customer requirements such as higher output, lower fuel consumption, comfortable V8 sound, high reliability and good driveability. An optimized combustion system coupled with a four-valve per cylinder configuration, high pressure common rail fuel injection system, new design combustion chamber and valve covered orifice (VCO) nozzle enables to meet 1998 U. S. Environmental Protection Agency (EPA) emission standards for heavy-duty diesel engines without exhaust gas recirculation (EGR) and aftertreatment.

Piston slap impact noise has been investigated using a piston secondary motion simulation. This simple model accurately estimates piston slap impact, by considering the hydrodynamic effects of the piston skirt oil film and the friction forces at various contact points. The results were compared with the actual piston motion measured by a link mechanism. Consequently, the calculation accuracy was confirmed to be sufficient to make precise estimates of piston slap noise.

This paper has clarified the noise generating mechanism on the BOSCH AD type fuel injection pump by using numerical and experimental analysis methods. The calculated vibration of each part has been verified to coincide well with the measured acceleration data. Based on the detailed analysis, the major noise source of the injection pump was found to originate from the tappet vibration caused by the steep pressure drop at the end of injection. After performing some parameter studies by using the simulation model, it turned out that some specifications of the injection pump influenced its sound power.

Recent progress in noise and vibration analysis technology had made great contributions to both noise level reduction and sound quality improvement in the interior noise of passenger cars. However, in spite of remarkable reductions in interior noise level, the sound quality in diesel passenger cars is still judged to be worse because of its different sound characteristics compared with gasoline versions. By using subjective testing, it was found that the main cause of poor sound quality in our test vehicle was the high contribution of relatively low frequency half-order multiple components, principally 2.5 and 3.5 order of engine rotation. The undesirable vibration transfer characteristics of the chassis was found to be one cause, but the half order components of powertrain vibration were also shown to be at a high level, and were the source of the excitation.

The authors developed a new method to calculate engine exciting forces by solving equations of motion using measured angular velocity fluctuation at the flywheel of the engine. Vibration response of a powerplant to the calculated engine exciting forces can be obtained by rigid body frequency response analysis with NASTRAN program using the measured value of the powerplant moment of inertia and the mount rubber characteristics. Calculated acceleration levels of a powerplant by this method were in close agreement with the measured ones. This method can be applied to estimate a powerplant vibration mode and levels when such parameters as engine mount locations are changed. As examples, the effect of reciprocating mass and cylinder-to-cylinder variation of fuel delivery were quantitatively discussed.