| 摘要 |
<p>The purpose of the present invention is to appropriately correct variation in the characteristics of a particulate matter (PM) sensor and to increase the detection precision of the sensor. The PM sensor (16) has a pair of electrodes (22) that collect PM in exhaust gas. The sensor output changes according to the amount of PM collected. If the sensor output has approached saturation, PM combustion control is executed, which combusts and removes PM between the electrodes (22) by using a heater (26). When the output sensitivity of the PM sensor (16) is to be corrected, first the cumulative amount of supplied power (W) is measured, which is the total amount of power supplied to the heater (26) up to when the sensor output changes from a first signal value (V1) to a second signal value (V2), while power is being supplied to the heater (26) by PM combustion control. Then, a sensitivity coefficient (K) including variation in output sensitivity is calculated on the basis of the cumulative amount of supplied power (W) and the sensor output at any point in time is corrected on the basis of this sensitivity coefficient (K). This enables smooth correction of the sensor sensitivity using the existing PM combustion control.</p> |
