FUEL PROPERTY DETERMINATION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

A fuel property determination apparatus for an internal combustion engine is applied to an internal combustion engine that is equipped with an ignition plug and an ignition timing controller. An electronic control unit provided in the fuel property determination apparatus executes a determination process of making a determination on a property of a fuel supplied to the internal combustion engine based on an ignition sufficiency ratio, during a predetermined period after startup of the internal combustion engine. The electronic control unit is configured to determine that the property of the fuel is heavy when a determination index value that is obtained by subjecting the ignition sufficiency ratio to a smoothing process is equal to or larger than a predetermined threshold. The electronic control unit is configured to set a smoothing coefficient to a value corresponding to each of a first period, a second period, and a third period.

主权项

1. A fuel property determination apparatus for an internal combustion engine including an ignition plug having a spark generation portion, the fuel property determination apparatus comprising:
an electronic control unit that is configured to: (i) correct an ignition timing as a timing for generating a spark from the spark generation portion, (ii) execute feedback control of an engine rotational speed such that an engine rotational speed converges to a target rotational speed, (iii) calculate an ignition sufficiency ratio during a preset period after startup of the internal combustion engine, and execute a determination process of making a determination on a property of a fuel supplied to the internal combustion engine based on the ignition sufficiency ratio, the ignition sufficiency ratio being a ratio of an advancement correction amount of the ignition timing to a maximum ignition correction width as a maximum width that allows the ignition timing to be corrected when the ignition timing is corrected in the feedback control, (iv) determine that the property of the fuel is heavy when a determination index value obtained by subjecting the ignition sufficiency ratio to a smoothing process is equal to or larger than a predetermined threshold, the smoothing process being a process of calculating a weighted average of an ignition sufficiency ratio obtained this time and a determination index value obtained last time, and (v) set a smoothing coefficient to a value corresponding to each of a first period, a second period, and a third period, the smoothing coefficient being an inverse of a coefficient corresponding to a weight of the ignition sufficiency ratio obtained this time in the smoothing process, the first period being a period from startup of the internal combustion engine to attainment of the target rotational speed by the engine rotational speed, the second period being a period from attainment of the target rotational speed by the engine rotational speed to lapse of a predetermined period, and the third period being a period after lapse of the predetermined period from attainment of the target rotational speed by the engine rotational speed.