Selective catalyst reduction system and method of controlling temperature of reducing agent injection module

1. A selective catalytic reduction system, comprising:

a reducing agent injection module installed in an exhaust pipe through which an exhaust gas is discharged from an engine, and including an injection nozzle configured to inject a reducing agent into the exhaust pipe;

a temperature calculator, implemented by a processor including electrical circuits, configured to calculate a temperature of the reducing agent injection module using information on the temperature of the reducing agent injection module; and

a temperature controller, implemented by a processor including electrical circuits, configured to control to increase a reducing agent injection amount of the reducing agent injection module when the calculated temperature of the injection nozzle exceeds an allowable temperature when the engine operates,

wherein the temperature controller is configured to decrease an engine RPM when the temperature of the injection nozzle exceeds an allowable temperature after the reducing agent injection amount is increased during the engine operation.

2. The selective catalytic reduction system of claim 1 , wherein the temperature calculator monitors the temperature of the reducing agent injection nozzle through a temperature model of the reducing agent injection nozzle.

3. The selective catalytic reduction system of claim 1 , wherein the temperature-related information includes at least one of an amount of the exhaust gas, an injection amount of the reducing agent, a temperature of the exhaust gas, a fan rotation speed of a cooling fan, a coolant temperature, an atmosphere temperature and an engine room temperature.

4. The selective catalytic reduction system of claim 1 , further comprising

a cooling fan installed in a side of the reducing agent injection module and configured to cool the reducing agent injection module.

5. The selective catalytic reduction system of claim 4 , wherein the temperature controller is configured to increase a rotation speed of the cooling fan when the calculated temperature of the injection nozzle exceeds an allowable temperature right after the engine stops.

6. The selective catalytic reduction system of claim 1 , wherein a selective reduction catalyst is installed in the exhaust pipe and the reducing agent injection module is installed in a front side of the selective reduction catalyst.

7. A method of controlling a temperature of a reducing agent injection module, comprising:

detecting information on a temperature of a reducing agent injection module installed in an exhaust pipe of an engine;

calculating a temperature of an injection nozzle of the reducing agent injection module using the temperature-related information; and

increasing a reducing agent injection amount of the reducing agent injection module when the calculated temperature of the injection nozzle exceeds an allowable temperature when the engine operates; and

decreasing an engine RPM when the temperature of the injection nozzle exceeds an allowable temperature after the reducing agent injection amount is increased during the engine operation.

8. The method of claim 7 , wherein calculating the temperature of the injection nozzle comprises

monitoring the temperature of the reducing agent injection module through a temperature model of the reducing agent injection module.

9. The method of claim 7 , wherein the temperature-related information includes at least one of an amount of the exhaust gas, an injection amount of the reducing agent, a temperature of the exhaust gas, a fan temperature, an atmosphere temperature and an engine room temperature.

10. The method of claim 7 , further comprising increasing a rotation speed of a cooling fan which is installed to cool the reducing agent injection module when the calculated temperature of the injection nozzle exceeds an allowable temperature right after the engine stops.