CORONA IGNITION SYSTEM AND METHOD FOR CONTROLLING A CORONA IGNITION DEVICE

摘要

A corona ignition system that can be operated with relatively low expenditure in the vicinity of its resonant frequency. For each ignition, impedance and frequency values are stored in a data structure and are allocated to a respective voltage value. The data structure is complemented by an adjustment variable whose value specifies whether the present frequency value of the present engine cycle has been classified as too high or too low. The value of the adjustment variable is determined anew in each engine cycle. To that end, a comparison is made between a present frequency value with an earlier frequency value and a present impedance value with an earlier impedance value. Based upon the comparison, a value can be assigned to the adjustment value to cause a lower or higher frequency value of the corona discharge in the next cycle.

主权项

1. A corona ignition system for igniting fuel in a combustion chamber of a cyclically operating internal combustion engine, comprising:
an oscillating circuit comprising an ignition electrode; a high-frequency generator configured for generating an alternating voltage from a primary voltage in order to excite the oscillating circuit; and a control unit configured for controlling the high-frequency generator, the control unit having a memory in which a data structure is provided, the data structure allocating an impedance value and a frequency value to successive intervals of voltage values, wherein the control unit is configured to:
determine an impedance value, a frequency value and a corresponding voltage value for each ignition, store the impedance and frequency values in the data structure and allocate the impedance and frequency values to the interval in which the corresponding voltage value is located;store a variable in the memory and use the variable to calculate a frequency value and set a frequency of the alternating voltage to the frequency value before a corona discharge is generated; andeach time new frequency and impedance values are allocated to one of the intervals and stored in the data structure, define the value of the variable anew by assigning to the variable a value that effects the setting of the frequency of the alternating voltage as follows:
to a lower value than the new frequency value if (i) the new frequency value is higher than the frequency value stored previously for this interval and if the new impedance value is higher than the impedance value stored previously for this interval, or (ii) the new frequency value is lower than the frequency value that was previously stored for this interval and the new impedance value is lower than the impedance value that was previously stored for this interval; andto a higher value than the new frequency value if (i) the new frequency value is higher than the frequency value that was previously stored for this interval and if the new impedance value is lower than the impedance value that was previously stored for this interval, or (ii) the new frequency value is lower than the frequency value that was previously stored for this interval and the new impedance value is higher than the impedance value that was previously stored for this interval.