Patent Document ID: 9255873
Application ID: 13183601
Patent Flag: 1

Claim One:
1. A controller for a particulate matter detection sensor, the particulate matter detection sensor including an attachment portion to which conductive particulate matter contained in gas is attached, and a pair of opposed electrodes spaced from each other at the attachment portion, the particulate matter detection sensor being adapted to output a detection signal corresponding to a resistance between the pair of opposed electrodes, the controller being adapted to calculate an amount of attached particulate matter based on a sensor detection value from the particulate matter detection sensor, the controller comprising: a signal output circuit connected to the particulate matter detection sensor such that the sensor detection value is changeable in a predetermined output range by the signal output circuit; a heater configured to heat the attachment portion so as to burn and remove the particulate matter attached to the attachment portion; a learning portion for obtaining the sensor detection value in a burning of the particulate matter due to heating of the heater, for calculating a sensor standard value in a state where the resistance between the pair of opposed electrodes is reduced based on the obtained sensor detection value, and for storing the sensor standard value as a learning value; a correcting portion for correcting the sensor detection value based on the sensor standard value stored by the learning portion, wherein: the sensor standard value is one of a zero-point learning value and an upper-limit learning value; the correcting portion reduces the sensor detection value by a correction value calculated based on the zero-point learning value, and increases the sensor detection value by a correction value calculated based on the upper-limit learning value; the controller further comprises a heater resistance calculating portion calculating a heater resistance; the learning portion determines both a state during the burning of the particulate matter and a state immediately after the burning and removing the particulate matter based on the calculated heater resistance, and executes both a zero-point learning and an upper-limit learning to calculate one of the zero-point learning value and the upper-limit learning value; and the controller is configured to: calculate an actual articulate matter amount based on the sensor detection value from the particulate matter detection sensor; and control a state of an engine based on the actual particulate matter amount.