Controller for injectors

A controller for injectors, the controller comprising processing circuitry and a memory module, wherein

• the memory module stores correction information,
• the correction information indicates a correspondence relationship between a torque difference and an injection correction value,
• control targets of the controller are the injectors,
• an internal combustion engine includes multiple cylinders,
• the injectors are provided for the respective cylinders so as to supply fuel to each of the cylinders,
• the processing circuitry is configured to repeatedly execute injection control during operation of the internal combustion engine, and
• the injection control includes:
• calculating a torque difference for each of the cylinders over a specified period of time during operation of the internal combustion engine, wherein
• the torque difference is a difference between an individual cylinder torque and an all-cylinder mean torque,
• the individual cylinder torque is a mean value of the torque of each of the cylinders over the specific period of time, and
• the all-cylinder mean torque is a mean value of the torque for all of the cylinders over the specific period of time;
• calculating, based on the correction information, the injection correction value in correspondence with the torque difference for each cylinder, wherein
• the injection correction value is a correction value for a fuel injection amount from each injector,
• in the correction information, the injection correction value for a case in which the individual cylinder torque is greater than the all-cylinder mean torque is a value indicating a decrease correction,
• the injection correction value for a case in which the individual cylinder torque is less than the all-cylinder mean torque is a value indicating an increase correction,
• the decrease correction decreases the fuel injection amount,
• the increase correction increases the fuel injection amount, and
• when an absolute value of the torque difference during the increase correction is equal to an absolute value of the torque difference during the decrease correction, a correction amount of the increase correction is greater than a correction amount of the decrease correction;
• calculating a corrected injection amount for each of the cylinders by using the injection correction value, wherein
• the corrected injection amount is obtained by correcting a base injection amount with the injection correction value, and
• the base injection amount corresponds to an operating state of the internal combustion engine;
• and
• supplying the corrected injection amount to each of the cylinders at a specified cycle through control of the injectors during the specific period of time, wherein
• the injection control includes a current injection control, a previous injection control, and a second previous injection control,
• the current injection control is a newly performed injection control,
• the previous injection control is performed prior to the current injection control,
• the second previous injection control is performed prior to the previous injection control, and
• in the current injection control, the processing circuitry is configured to
• when calculating the torque difference, store the individual cylinder torque obtained through the supply of the corrected injection amount by the previous injection control in the memory module,
• when calculating the corrected injection amount, store an increased-injection cylinder in the memory module, the corrected injection amount of the increased-injection cylinder being greater than the base injection amount,
• when calculating the torque difference, determine whether the individual cylinder torque obtained through the supply of the corrected injection amount in the previous injection control is less than the individual cylinder torque obtained through the supply of the corrected injection amount in the second previous injection control, for the cylinder stored as the increased-injection cylinder in the previous injection control,
• if the determination is affirmative when calculating the injection correction value, set the injection correction value of the increased-injection cylinder to a specific correction value, the specific correction value being a value indicating the decrease correction, the specific correction value being determined in advance regardless of the torque differences of the increased-injection cylinder, and
• if the determination is negative, set the injection correction value of the increased-injection cylinder to a value that corresponds to the torque differences of the increased-injection cylinder based on the correction information.