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Technical Paper

Inaudible Knock and Partial-Burn Detection Using In-Cylinder Ionization Signal

2003-10-27
2003-01-3149
Internal combustion engines are designed to maximize power subject to meeting exhaust emission requirements and minimizing fuel consumption. Maximizing engine power and fuel economy is limited by engine knock for a given air-to-fuel charge. Therefore, the ability to detect engine knock and run the engine at its knock limit is a key for the best power and fuel economy. This paper shows inaudible knock detection ability using in-cylinder ionization signals over the entire engine speed and load map. This is especially important at high engine speed and high EGR rates. The knock detection ability is compared between three sensors: production knock (accelerometer) sensor, in-cylinder pressure and ionization sensors. The test data shows that the ionization signals can be used to detect inaudible engine knock while the conventional knock sensor cannot under some engine operational conditions.
Technical Paper

MBT Timing Detection and its Closed-Loop Control Using In-Cylinder Pressure Signal

2003-10-27
2003-01-3266
MBT timing for an internal combustion engine is also called minimum spark timing for best torque or the spark timing for maximum brake torque. Unless engine spark timing is limited by engine knock or emission requirements at a certain operational condition, there exists an MBT timing that yields the maximum work for a given air-to-fuel mixture. Traditionally, MBT timing for a particular engine is determined by conducting a spark sweep process that requires a substantial amount of time to obtain an MBT calibration. Recently, on-line MBT timing detection schemes have been proposed based upon cylinder pressure or ionization signals using peak cylinder pressure location, 50 percent fuel mass fraction burn location, pressure ratio, and so on. Because these criteria are solely based upon data correlation and observation, both of them may change at different engine operational conditions. Therefore, calibration is still required for each MBT detection scheme.
Technical Paper

Soft Spray Formation of a Low-Pressure High-Turbulence Fuel Injector for Direct Injection Gasoline Engines

2002-10-21
2002-01-2746
Currently, high-pressure fuel systems and swirl injectors dominate direct injection spark ignition (DISI) engine applications worldwide. Besides its advantage of good atomization due to the high pressure, this technology also has many inherent drawbacks, such as, high system cost, complicated system configuration, excessive wall wetting, lack of spray tailoring flexibility, etc., which limit the benefits available from the DISI concept. To overcome these drawbacks, a low-pressure direct injection (LPDI) fuel injector was developed which utilizes a novel high-turbulence nozzle to produce a soft spray, with droplet size comparable to the high-pressure swirl injector sprays, but much reduced penetration. This unique nozzle design provides a degree of independent control of injector flow, spray droplet size, spray angle, penetration, and spray distribution pattern.
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