Showing papers on "Spark (mathematics) published in 2000"

Numerical simulation of spark ignition including ionization

Abstract: A detailed understanding of the processes associated with spark ignition, as a first step during combustion, is of great importance for clean operation of spark ignition engines. In the past 10 years, a growing concern for environmental protection, including low emission of pollutants, has increased the interest in the numerical simulation of igniton phenomena to guarantee sucessful flame kernel development event for lean mixtures. However, the porcess of spark ignition in a combustible mixture is not yet fully undrstood. The use of detailed reaction mechanisms, combined with electrodynamical modeling of the spark, is necessary to optimize spark ignition for lean mixtures. This work presents the simulation of the coupling of flow, chemical reactions, and transport with discharge processes including ionization in order to investigate the development of a stable flame kernel initiated by an electrical park in methane/air mixtures. A transport model taking into account the interactions of charged particles has been incorporated in the flow model. This model is based on the Chapman-Enskog theory with an extension for polyatomic gases and considers resonant charge transfer and ambipolar diffusion for the computation of the transport coefficients. A two-dimensional code to simulate the early stages of flame development, shortly after the breakdown discharge, has been developed. The modeling includes an equation for the electrical field. The spark plasma channel left behind by the breakdown is incorporated into the initial conditions. Due to the fast expansion of the plasma channel, a complicated flowfield develops after the emission of a shock wave by the expanding channed. The second phase, that is, the development of a propagating flame and the flame kernel expansion, can last up to several milliseconds and is dominated by diffusive processes and chemical reactions.

Geometrical study of spark ignition in two dimensions

Abstract: Spark ignition, as the first step during the combustion in Otto engines, has a profound impact on the further development of the flame kernel. Over the last ten years growing concern for environment protection, including low emission of pollutants has increased the interest in the numerical simulation of ignition phenomena to guarantee successful flame kernel development even for lean mixtures. However, the process of spark ignition in a combustible mixture is not yet fully understood. The use of detailed reaction mechanisms, combined with electrodynamical modelling of the spark, is necessary to optimize ignition of lean mixtures. This work presents simulations of the coupling of flow, chemical reactions and transport with discharge processes in order to investigate the development of a stable flame kernel initiated by an electrical spark. A two-dimensional code to simulate the early stages of flame kernel formation, shortly after the breakdown discharge, has been developed. The model includes Joule heati...

Charge control for direct injection spark ignition engines with EGR

Abstract: Modern automotive engines rely increasingly on high performance estimation and control algorithms to deliver the expected performance benefits. This paper discusses a number of control problems and issues that arise in the design of a charge controller for a lean-burn direct injection spark ignition engine with exhaust gas recirculation (EGR). To deal with uncertainties and parameter variations that can significantly affect the engine performance, the use of feedback and adaptive controllers is shown to be essential.

High efficiency, extended life spark plug having shaped firing tips

Abstract: A spark plug is provided which is suitable for use in a spark ignition system for an internal combustion engine. The spark plug is equipped with a specially configured firing tip on each of its electrodes for the purpose of minimizing the demand voltage of the spark plug, as well as extending the life of the spark plug by maximizing the time over which the demand voltage will remain within an acceptable level. For this purpose, the firing tips are configured such that their firing surfaces include at least three edges and three corners which serve as arc initiation sites of a relatively low resistance arc path between the electrodes.

Non-Linear Model-Based Throttle Control

Abstract: Spark ignited engines require accurate control of both air and fuel, and one important component in this system is the throttle servo. A non-linear throttle model is built and used for control desi ...

Method and device for electronic spark control in the event of the failure of the phase detector

Abstract: The invention relates to a method and a device for the electronic spark control in the event of the failure of the phase detector, which, if the double ignition mode is not activated, carry out the normal electronic spark control individually for each cylinder. If the double ignition mode is activated in the event of the failure of the phase detector, the electronic spark control is carried out using a measure that is not individually performed for each cylinder. Such a cylinder non-individual measure could be a retarded ignition security adjustment or an electronic spark control with a knock recognition threshold for all cylinders.

An incremental analysis of spark paths in air using 3-dimensional image processing

Abstract: A video camera has been used to record the path of spark breakdowns across a positive point/plane air-gap. By using a prism as a mirror, two images were obtained from which the path could be determined in three dimensions by subsequent computer processing and analysis. Images were analyzed for each of five angular positions of the point electrode's axis, the gap remaining constant. The fractal dimension of each path was determined and found to increase slightly with the inclination of the pointed electrode. Each spark appeared to have propagated semi-randomly in a direction which included a 'memory' factor, that is, it tended to follow the previous direction while moving monotonically towards the opposite electrode. This was confirmed by an analysis of 400 spark paths which showed that each section has a specific relationship to the previous section, but that there is a wide variation around this mean which leads to the characteristic shape of a spark path. Simulations based on these results yield spark tracks which look similar to those measured and have similar fractal dimensions. These analyses strongly suggest that the development of spark paths in air is by successive steps and in a direction suggested by an angular probability distribution which is related to the field at the tip of the propagating leader.

A method for spark rejection in ultraviolet flame detectors

Abstract: A novel method is presented to render ultraviolet (UV) flame detectors insensitive to ignition spark radiation. The method involves isolating the signal due to the sparks from the UV sensor output and subtracting a DC signal proportional to it from the output of the flame detector sensor system. A practical demonstration of the method is given using a commercially available UV flame detector with the addition of an analog circuit to perform the necessary signal processing. A selectivity improvement to spark radiation of greater than 130 has been obtained. The method is robust in that it is independent of the distance between the light source and the flame detector and has been designed to work with different spark generators found on the market. The analog circuit is simple, requiring few components, thus ensuring rugged, fail-safe operation and low cost.

Spark plug having an encapsulated electrode gap

Abstract: Encapsulated spark plugs improve combustion control in spark ignited engines. The present invention improves reliability and life of an encapsulated spark plug. A spark plug shell has a connection region and an orificed region, and a tip portion. The present invention provides improved heat transfer from the tip portion through the orificed region to the connection region. An access orifice provides access to set an electrode gap.

Ignition unit for internal combustion engine

Abstract: For minimizing spark energy and improving durability of a spark plug ( 13 ) without controlling a time for energizing a primary wiring (L 1 ); the ignition unit ( 1,2 and 3 ) for an internal combustion engine is arranged in that actions of a transistor ( 17 ) are controlled by an ECU ( 19 ) to abruptly interrupt a primary current (i 1 ) such that high voltage for ignition induced to a secondary wiring (L 2 ) is applied on the spark plug ( 13 ) for generating spark discharge. For forcibly interrupting spark discharge at a spark discharge duration, the ECU ( 19 ) switches the thyristor ( 21 and 210 ) ON to supply current to the primary wiring (L 1 ) for forcibly interrupting the spark discharge. By controlling the spark discharge duration to be optimum on a basis of an operating condition of the internal combustion engine, it is possible to restrict generation of multiple discharge and to restrict exhaustion of electrodes of the spark plug ( 13 ). It is also possible to realize spark discharge through a simple arrangement of low cost by simply providing a single thyristor ( 21 and 210 ).

System and method for ignition spark energy optimization

Abstract: A method for controlling spark energy from a spark plug (52) of a combustion engine (20). The method includes determining a spark energy intensity based on at least one engine operating condition, determining a period of time to supply a current to an ignition coil (60) connected to the spark plug to achieve the determined spark energy intensity from the spark plug as a function of a voltage supplied from a power supply (54) to the ignition coil, and connecting the power supply to the ignition coil for the determined time period.