Method for regenerating a particulate collection filter and an exhaust emission control system with a particulate collection filter

An exhaust emission control system with a particulate collection filter regenerated by the use of a regenerative gas comprising:

• determining means for determining when the filter must be regenerated;
• partial combustion means for causing particulate combustion in only the downstream part of said filter in the flow of said regenerative gas when the filter must be regenerated;
• and
• combustion propagating means for causing particulate combustion in the downstream part of said filter to propagate toward the upstream part of said filter in the flow of said regenerative gas, wherein said flow of said regenerative gas is in a direction from said upstream part of said filter towards said downstream part of said filter.

An exhaust emission control system with a particulate collection filter regenerated by the use of a regenerative gas comprising:

• determining means for determining when the filter must be regenerated;
• partial combustion means for causing particulate combustion in only the downstream part of said filter in the flow of said regenerative gas when the filter must be regenerated;
• and
• combustion propagating means for causing said particulate combustion in the downstream part of said filter to propagate toward the upstream part of said filter in the flow of said regenerative gas, wherein said filter carries a high-temperature-active catalyst in the upstream part of said filter in the flow of the regenerative gas and a low-temperature-active catalyst in the downstream part of said filter, and wherein said partial combustion means has fuel supplying means for supplying fuel to said filter when said filter must be regenerated and only said low-temperature-active catalyst is active.

An exhaust emission control system with a particulate collection filter regenerated by the use of a regenerative gas comprising:

• a determining means for determining when the filter must be regenerated;
• a regenerative gas supplying means for supplying a regenerative gas to one end of said filter when the filter must be regenerated such that particulate combustion propagates from said one end toward the downstream part of said filter in the flow of the regenerative gas;
• and
• reversing means for reversing the supply of the regenerative gas to the other end of said filter such that particulate combustion propagates from said other end toward the downstream part of said filter in the flow of the regenerative gas before temperature in any part of said filter becomes higher than a predetermined temperature due to heat produced by the particulate combustion.