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Technical Paper

Combustion Characteristics Detection for Low Pressure Direct Injection Engines Using Ionization Signal

2006-10-16
2006-01-3317
It is well-known that in-cylinder ionization signals can be used for detecting combustion characteristics of IC (Internal Combustion) engines. For example, engine misfire, incomplete combustion (or partial-burn), knock, MBT (Minimum spark advance for Best Torque) timing and combustion stability can be detected using in-cylinder ionization signals. In addition, closed loop combustion spark timing control strategies have been developed to control engine MBT timing and to manage spark timing advance (knock) and retard (incomplete combustion) limits. In-cylinder ionization signals can also be used for closed loop control of maximum equivalence ratio (lean limit) at a desired combustion stability level. Up to now, most of the ionization applications have been for PFI (Port Fuel Injection) engines. This paper presents ionization detection for gasoline Direct Injection (DI) engines.
Technical Paper

A High Speed Flow Visualization Study of Fuel Spray Pattern Effect on Mixture Formation in a Low Pressure Direct Injection Gasoline Engine

2007-04-16
2007-01-1411
In developing a direct injection gasoline engine, the in-cylinder fuel air mixing is key to good performance and emissions. High speed visualization in an optically accessible single cylinder engine for direct injection gasoline engine applications is an effective tool to reveal the fuel spray pattern effect on mixture formation The fuel injectors in this study employ the unique multi-hole turbulence nozzles in a PFI-like (Port Fuel Injection) fuel system architecture specifically developed as a Low Pressure Direct Injection (LPDI) fuel injection system. In this study, three injector sprays with a narrow 40° spray angle, a 60°spray angle with 5°offset angle, and a wide 80° spray angle with 10° offset angle were evaluated. Image processing algorithms were developed to analyze the nature of in-cylinder fuel-air mixing and the extent of fuel spray impingement on the cylinder wall.
Technical Paper

Quantitative Characterization of Near-Field Fuel Sprays by Multi-Orifice Direct Injection Using Ultrafast X-Tomography Technique

2006-04-03
2006-01-1041
A low-pressure direct injection fuel system for spark ignition direct injection engines has been developed, in which a high-turbulence nozzle technology was employed to achieve fine fuel droplet size at a low injection pressure around 2 MPa. It is particularly important to study spray characteristics in the near-nozzle region due to the immediate liquid breakup at the nozzle exit. By using an ultrafast x-ray area detector and intense synchrotron x-ray beams, the interior structure and dynamics of the direct injection gasoline sprays from a multi-orifice turbulence-assisted nozzle were elucidated for the first time in a highly quantitative manner with μs-temporal resolution. Revealed by a newly developed, ultrafast computed x-microtomography technique, many detailed features associated with the transient liquid flows are readily observable in the reconstructed spray.
Journal Article

Gasoline Fuel Injector Spray Measurement and Characterization - A New SAE J2715 Recommended Practice

2008-04-14
2008-01-1068
With increasingly stringent emissions regulations and concurrent requirements for enhanced engine thermal efficiency, a comprehensive characterization of the automotive gasoline fuel spray has become essential. The acquisition of accurate and repeatable spray data is even more critical when a combustion strategy such as gasoline direct injection is to be utilized. Without industry-wide standardization of testing procedures, large variablilities have been experienced in attempts to verify the claimed spray performance values for the Sauter mean diameter, Dv90, tip penetration and cone angle of many types of fuel sprays. A new SAE Recommended Practice document, J2715, has been developed by the SAE Gasoline Fuel Injection Standards Committee (GFISC) and is now available for the measurement and characterization of the fuel sprays from both gasoline direct injection and port fuel injection injectors.
Technical Paper

Engine Position Tracking at Shutdown

2005-04-11
2005-01-0048
Engine position synchronous control of fuel injection and spark ignition at engine start can reduce regulated emissions, and improve start quality. Synchronous fuel and ignition control requires full 720° engine position information. Emissions and start quality benefits are gained if engine position is available at key-on before initial engine rotation. Typical engine position sensor sets require substantial engine rotation before engine position is initialized. Tracking engine stop position, for use on the next start, eliminates the initial engine angular travel required for synchronization. The previous stop position of the engine is stored in non-volatile memory, giving engine position immediately at start. This approach is applicable for systems in which the engine controller remains powered for some time after key-off. As the engine stops, direction reversals are common.
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.
Technical Paper

Simulation of Pressure Pulsations in a Gasoline Injection System and Development of an Effective Damping Technology

2005-04-11
2005-01-1149
In today's search for a better fuel economy and lower emissions, it is essential to precisely control the injected fuel quantity, as demanded by the engine load, into each of the engine cylinders. In fuel injection systems, the pressure pulsations due to the rapid opening and closing of the injectors can cause uneven injected fuel amounts between cylinders. In order to develop effective techniques to reduce these pressure pulsations, it is crucial to have a good understanding of the dynamic characteristics of such fuel injection systems. This paper presents the benefits of using simulation as a tool to analyze the dynamic behaviors of a V8 gasoline injection system. The fuel system modeling, based on a one-dimensional (1D) lumped parameter approach, has been developed in the AMESim® environment. The comparison between the simulation results and the experimental data shows good agreement in fluid transient characteristics for both time and frequency domains.
Technical Paper

Optimizing the Effects of Body Attachment Stiffness on Steering Column In-Vehicle Modes

2001-03-05
2001-01-0041
This paper presents an unambiguous and intuitive method for identification of steering column resonant (SCR) mode of vibration. One simple but overlooked technique to determine the SCR mode in-vehicle is to provide local stiffnesses of the body locations where the Instrument Panel (IP) attaches, to the IP suppliers to be used in their design and development. This paper describes how this technique is useful in predicting the first few important in-vehicle steering column modes for different classes of vehicles, with examples presented in each class. The results obtained from such analyses are compared against those from direct in-buck simulations. This technique is not limited to its application in developing IP systems, but can easily be extended to include other systems such as seats, fuel tanks, etc. Also it is shown that a design optimization analysis may be performed using these attachment stiffnesses as design variables resulting in a system level solution.
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