Patent ID: 7162867
Filing Date: 2007-01-16
Classification: F01N,Y02T

Abstract:
1. An exhaust gas purifying device for an internal combustion engine, the purifying device comprising: a particulate filter that is provided midway in an exhaust passage, the particulate filter collecting particulate matters contained in exhaust gas, wherein particulate matters accumulate on the particulate filter by being collected by the particulate filter; a differential pressure detecting means that detects differential pressure of the particulate filter; and a control means that performs a forcible regeneration, in which particulate matters accumulating on the particulate filter are burned and removed to regenerate the particulate filter, when an accumulating amount of particulate matters accumulating on the particulate filter becomes a predetermined regeneration demand amount, wherein the control means includes an accumulating amount calculating means, which calculates the accumulating amount in accordance with an accumulating characteristic and at least the differential pressure, the control means defines the accumulating characteristic that is a relationship between the accumulating amount and the differential pressure, the control means defines a former increasing characteristic line on a side, on which the accumulating amount is equal to or less than an accumulating amount defined on a predetermined transition point, wherein the former increasing characteristic line is a substantially straight line passing through an initial point, on which the accumulating amount is zero, the control means defines a latter increasing characteristic line on a side, on which the accumulating amount is greater than the accumulating amount defined on the transition point, wherein the latter increasing characteristic line is a substantially straight line having a slope gentler than a slope of the former increasing characteristic line, when the differential pressure increases from the initial point along the former increasing characteristic line, and when the differential pressure becomes greater than a differential pressure defined on the transition point, the differential pressure increases along the latter increasing characteristic line, the control means defines a limit accumulating characteristic with a substantially straight line that passes through the initial point and has a slope substantially the same as the slope of the latter increasing characteristic line, the control means further includes a forcible transition means that performs a forcible transition when the accumulating amount, which is calculated in accordance with the accumulating characteristic, enters a predetermined forcible transition area, particulate matters accumulating on the particulate filter are burned in the forcible transition until the accumulating characteristic substantially becomes the limit accumulating characteristic, and the accumulating amount calculating means moves the accumulating characteristic to the limit accumulating characteristic until the accumulating characteristic substantially becomes the limit accumulating characteristic when particulate matters accumulating on the particulate filter are burned by the forcible transition means.