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Exhaust particulate emissions from a 4-cylinder, 2.25 liter spark ignition engine were measured and characterized. A single-stage ejector-diluter system was used to dilute and cool the exhaust sample for measurement. The particulate measurement equipment included a condensation nucleus counter and a scanning mobility particle sizer. Exhaust measurements were made both upstream and downstream of the catalytic converter using three different fuels. Unlike particulate emissions in diesel engines, spark ignition exhaust particle emissions were found to be highly unstable. Typically, a stable “baseline” concentration on the order of 105 particles/cm3 is emitted. Occasionally, however, a “spike” in the exhaust particle concentration is observed. The exhaust particle concentrations observed during these spikes can increase by as much as two orders of magnitude over the baseline concentration.

Soot-related oil thickening problems have been reported over the years by multiple OEMs in Europe, Japan, and in the U.S.A (1,2,3). The earliest problems, from the late 1970s, were often attributed to adverse changes in operation [lower engine speeds, heavy loads and low air/fuel ratio, or severe operation such as stop-and-go service (3)] which led to a high soot generation rate. In the late 1980s, the emission legislation became more stringent and soot-related oil thickening concerns resurfaced. It appeared that even engines that produced a relatively low level of soot in the exhaust gas showed a high level of soot contamination in the lubricant (4). For the oil and oil additive industry, the Mack T-7 engine test offered a useful tool to evaluate the ability of oils to disperse soot, but it has been noted that the industry remains without a test based on a European engine to adequately evaluate an oil's ability to disperse diesel engine soot.

An electronic engine management system has been developed to control both ignition timing and air-fuel (A/F) ratio to maximize fuel economy. Both controls employ feedback techniques and are therefore intrinsically adaptable to a wide variety of models, as required for a universal retrofit market. The ignition control loop monitors the position of the combustion pressure peak while the mixture control loop senses the lean limit as defined by a roughness threshold. Test results demonstrate fuel economy and transient operation. A brief background to the New Zealand energy conservation program is in included as background to the system’s specification.

At present, combustion pressure sensors find widespread use in basic engine research and development. In the future they could provide the essential information for closed loop engine control (of both fuel mixture and ignition timing) and diagnostics. The quartz piezoelectric device is the most familiar; its concept has been extended to piezo-ceramic configurations seated beneath or inside a sparkplug. This paper presents preliminary results for a novel fiber-optic pressure sensor incorporated into a spark-plug. Head-stud transducers are also described.

Experiments were performed to measure the average and time-resolved particle number emissions and number-weighted particle size distributions from a gasoline direct injection (GDI) engine. Measurements were made on a late model vehicle equipped with a direct injection spark ignition engine. The vehicle was placed on a chassis dynamometer, which was used to load the engine to road load at five different vehicle speeds ranging from 13 - 90 km/hr. Particle number emissions were measured using a TSI 3020 condensation nucleus counter, and size distributions were measured using a TSI 3934 scanning mobility particle sizer. Average polydisperse number concentration was found to increase from 1.1 × 108 particles/cm3 at 13 km/hr to 2.8 × 108 particles/cm3 at 70 km/hr. Under a closed-loop, stoichiometric homogeneous charge operating mode at 90 km/hr, number emissions fell to 9.3 × 107 particles/cm3 (at all other operating conditions, the engine was in a lean stratified charge operating mode).

Experiments were undertaken to determine some of the characteristics of exhaust particulate emissions in two port fuel injected spark ignition engines. A 2.3L 1993 GM Quad-4 engine and a 4.6L 1994 Ford V8 were tested. Sampling and dilution were accomplished through the use of a single-stage, low residence-time ejector diluter; dilution ratios were maintained at approximately 15:1. Number concentration was measured with a TSI 3020 condensation nucleus counter, and size distributions were measured using two scanning mobility particle sizers. The Quad-4 engine was used to determine the effects of the catalytic converter and deposit control additives on particulate emissions. The catalyst was found to remove particles with an efficiency as high as 78% at low power conditions (∼7 kW), dropping steeply with power, reaching a minimum value of approximately 10% at moderate power conditions (∼18 kW).