Patent ID: 8539755

Claim:
A device for purifying exhaust gas of an internal combustion engine, comprising: at least one high efficiency filter arranged in at least one passage for feeding at least one fluid into a combustion chamber to remove fine particles smaller than 50 nanometers that serve as nuclei for forming PM, wherein said fine particles smaller than 50 nanometers are removed to decrease the number of PM particles emitted from the internal combustion engine; at least one by-pass that by-passes said at least one high efficiency filter; valve means for controlling a change-over of the flow of the fluid into said at least one high efficiency filter, the flow of the fluid into said at least one by-pass and the flow of the fluid backward through said at least one high efficiency filter; and a control device including control logic for calculating the number of the emitted PM particles depending upon the operating conditions of the internal combustion engine to control the fluid; wherein when the calculated number of the PM particles exceeds a predetermined value, the fluid is controlled to pass through said high efficiency filter; when the calculated number of the PM particles is smaller than the predetermined value, the control device determines if PM is formed based upon the operating conditions; wherein when the PM is formed, the fluid is controlled to pass through said by-pass, and when the PM is not formed, the fluid is controlled to flow backward through said high efficiency filter to clean said high efficiency filter.