Image Number 15 for United States Patent #6286306.
A system for purifying exhaust gas generated by an internal combustion engine having a bypass exhaust gas passage branching from an exhaust pipe which is opened or closed by a switch-over valve, and an adsorbent which adsorbs unburneds component in the exhaust gas installed at the bypass exhaust passage. In the system, when the engine operation is within a high engine speed and high load region, the switch-over valve is operated to open the bypass exhaust gas passage to reduce noise due to switch-over valve chattering, etc. Similarly, the bypass exhaust gas passage is opened at that range, when the exhaust gas temperature is greater or equal to a predetermined value, to introduce high temperature exhaust gas to burn away cloggy material adhered to the adsorbent which would otherwise deteriorate or degrade the adsorbent.
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