Method and device for detecting pressure difference of particulate filter

A particulate filter differential pressure sensing method comprising:

• sensing by an upstream pressure sensor a first pressure on an upstream side of a particulate filter disposed in an exhaust passage of an internal combustion engine;
• sensing by a downstream pressure sensor a second pressure on a downstream side of the particulate filter;
• calculating an upstream-to-downstream differential pressure of the particulate filter;
• correcting a sensed value of the first pressure or the second pressure so as to reduce a difference in waveform phase between the first pressure and the second pressure;
• implementing the calculation of the upstream-to-downstream differential pressure based on the corrected sensed value of the first pressure or the second pressure;
• calculating a phase compensation time period based on rotation speed of the internal combustion engine, wherein the phase compensation time period corresponds to the difference in waveform phase;
• and
• setting the corrected sensed value to a sensed value of one of the first pressure and the second pressure the phase compensation time period before, wherein the one of the first pressure and the second pressure is more advanced in waveform phase than the other.

A particulate filter differential pressure sensing device comprising:

• an upstream pressure sensor structured to sense a first pressure on an upstream side of a particulate filter disposed in an exhaust passage of an internal combustion engine;
• a downstream pressure sensor structured to sense a second pressure on a downstream side of the particulate filter;
• a phase compensation section configured to correct a sensed value of the first pressure or the second pressure so as to reduce a difference in waveform phase between the first pressure and the second pressure;
• and
• a differential pressure calculation section configured to calculate an upstream-to-downstream differential pressure of the particulate filter based on the corrected sensed value of the first pressure or the second pressure;
• wherein a first for-sensor pipe that branches from an exhaust pipe provided with the particulate filter and leads to the upstream pressure sensor and a second for-sensor pipe that branches from the exhaust pipe and leads to the downstream pressure sensor are different in path length from each other;
• and
• wherein the phase compensation section is configured to calculate the corrected sensed value by retarding the sensed value of one of the upstream pressure sensor and the downstream pressure sensor corresponding to one of the first for-sensor pipe and the second for-sensor pipe that is shorter in path length than the other.

A particulate filter differential pressure sensing device comprising:

• an upstream pressure sensor structured to sense a first pressure on an upstream side of a particulate filter disposed in an exhaust passage of an internal combustion engine;
• a downstream pressure sensor structured to sense a second pressure on a downstream side of the particulate filter;
• a phase compensation section configured to correct a sensed value of the first pressure or the second pressure so as to reduce a difference in waveform phase between the first pressure and the second pressure;
• and
• a differential pressure calculation section configured to calculate an upstream-to-downstream differential pressure of the particulate filter based on the corrected sensed value of the first pressure or the second pressure;
• wherein the phase compensation section is configured to:
• calculate a phase compensation time period based on rotation speed of the internal combustion engine, wherein the phase compensation time period corresponds to the difference in waveform phase;
• and
• set the corrected sensed value to a sensed value of one of the first pressure and the second pressure the phase compensation time period before, wherein the one of the first pressure and the second pressure is more advanced in waveform phase than the other.