CONTROL SYSTEM AND CONTROL METHOD FOR INTERNAL COMBUSTION ENGINE

摘要

A control system for an engine includes a limiting current gas sensor includes a pumping cell arranged in the exhaust passage of the engine and an ECU. The ECU is configured to: execute step-up operation for increasing a voltage applied between a pair of electrodes of the pumping cell from a first voltage to a second voltage, then, execute step-down operation for reducing the applied voltage from the second voltage to a third voltage within a second period; acquire an air-fuel ratio of the exhaust gas multiple times within a first period from a start of the step-up operation to a start of the step-down operation; acquire a first waveform characteristic value indicating a characteristic of a waveform of current within the second period; and estimate an actual concentration of sulfur in fuel by using the first waveform characteristic value and the acquired air-fuel ratios.

主权项

1. A control system for an internal combustion engine, the internal combustion engine including an exhaust passage and a limiting current gas sensor, the limiting current gas sensor including a pumping cell arranged in the exhaust passage, exhaust gas in the exhaust passage being introduced to the pumping cell, the control system comprising:
an electronic control unit configured to:
(i) execute step-up operation for increasing a voltage applied between a pair of electrodes of the pumping cell from a first voltage to a second voltage higher than the first voltage;(ii) execute step-down operation for, after completion of the step-up operation, reducing an applied voltage from the second voltage to a third voltage lower than the second voltage;(iii) acquire an air-fuel ratio of the exhaust gas multiple times within a first period from a start of the step-up operation to a start of the step-down operation;(iv) acquire a first waveform characteristic value indicating a characteristic of a waveform of current flowing between the pair of electrodes within a second period in which the step-down operation is executed; and(v) estimate an actual concentration of sulfur in fuel of the internal combustion engine by using the first waveform characteristic value and a plurality of acquired air-fuel ratios.