SCR system and method for the purging thereof
View Patent ↗SCR system for treating the exhaust gases of an internal combustion engine, this system comprising a line for feeding a urea solution into the exhaust gases and a pump capable both of feeding the urea solution into the exhaust gases and of purging at least one part of the line by sucking a gas therethrough by means of a suction device, this system also comprising a control unit capable of activating and/or deactivating the operation of the pump and that of the suction device in a sequential manner in the course of one and the same purge procedure.
1. A Selective Catalytic Reduction (SCR) system for treating the exhaust gases of an internal combustion engine, the system comprising:
a line that feeds a urea solution into the exhaust gases;
a pump that both feeds the urea solution into said exhaust gases and purges at least one part of the line by sucking a gas through the at least one part by a suction device, the pump including an outlet;
a timer;
a pressure sensor that measures the pressure at the pump outlet; and
an electronic control unit configured to:
activate and deactivate operation of the pump and operation of the suction device in a sequential manner in the course of one and a same purge procedure; and
start the timer and actuate the pump in a purge mode if the pressure measured by the pressure sensor drops below a reference value,
wherein the timer is configured to control the suction device to open and close at predetermined times after actuating the pump.
2. The SCR system according to claim 1 , wherein the electronic control unit is further configured to activate the purge after a certain period when the engine is shut off.
3. The SCR system according to claim 1 , wherein the pump is a rotary positive-displacement pump of a gear pump type.
4. The SCR system according to claim 1 , further comprising:
an injector that injects the urea solution into the exhaust gases,
wherein the suction device is either a valve that sucks up air or exhaust gases that is located close to the injector, or is constituted by the injector itself.
5. The SCR system according to claim 1 , wherein either the pump rotates in two opposite directions, or the system comprises a 4-way valve that reverses flow in the line without changing the direction of rotation of the pump.
6. The SCR system according to claim 1 , wherein the electronic control unit is further configured to deactivate the operation of the pump before deactivating the operation of the suction device.
7. A Selective Catalytic Reduction (SCR) system for treating the exhaust gases of an internal combustion engine, the system comprising:
a line that feeds a urea solution into the exhaust gases;
a pump that both feeds the urea solution into said exhaust gases and purges at least one part of the line by sucking a gas through the at least one part by a suction device, the pump including an outlet;
a timer;
a pressure sensor that measures the pressure at the pump outlet; and
an electric control unit configured to:
activate and deactivate operation of the pump and operation of the suction device in a sequential manner in the course of one and a same purge procedure;
start the timer if the pressure measured by the pressure sensor drops below a reference value; and
actuate the pump by the electronic control unit in a purge mode at the end of a predetermined time interval detected by said timer,
wherein the timer is configured to open and close the suction device at predetermined times after actuating the pump.