Fluid injection control system

1. An aftertreatment system for treating exhaust gas discharged from a combustion engine, the aftertreatment system comprising:

a tank containing a volume of a fluid;

an injector configured to inject the fluid into a stream of exhaust gas discharged from the combustion engine;

a supply conduit fluidly connecting the tank and the injector;

a pump pumping the fluid from the tank to the injector;

a pressure sensor engaging the supply conduit; and

a control module in communication with the pressure sensor and the pump and controlling the pump based on first and second measurements from the pressure sensor, the first measurement indicative of a first pressure within the supply conduit when the pump is operating, the second measurement from the pressure sensor indicative of a pressure head within the supply conduit when the pump is not operating, the controller determining a correction value based on the second measurement and applying the correction value to future pressure sensor measurements when the pump is operating to account for the pressure head.

2. The aftertreatment system of claim 1 , wherein the control module controls operation of the pump based on a sum of the first and second measurements.

3. The aftertreatment system of claim 1 , wherein the second measurement is taken when the supply conduit is filled with the fluid.

4. The aftertreatment system of claim 1 , further comprising a return conduit fluidly coupling the injector and the tank, wherein the second measurement is taken with the return conduit empty of the fluid.

5. The aftertreatment system of claim 1 , further comprising a return conduit fluidly coupling the injector and the tank, wherein the second measurement is taken with the return conduit filled with the fluid.

6. The aftertreatment system of claim 1 , wherein the fluid includes urea.

7. The aftertreatment system of claim 1 , wherein the fluid includes a hydrocarbon fluid.

8. An aftertreatment system for treating exhaust gas discharged from a combustion engine, the aftertreatment system comprising a tank containing a volume of a fluid; an injector configured to inject the fluid into a stream of exhaust gas discharged from the combustion engine; a pump pumping the fluid from the tank to the injector; and a control module in communication with the pump and operable to determine a correction value to account for a pressure head corresponding to a vertical height of the injector, the control module applying the correction value to control the pump.

9. The aftertreatment system of claim 8 , further comprising a pressure sensor in communication with the control module and engaging a supply conduit fluidly connecting the tank and the injector, wherein the control module controls the pump based on data received from the pressure sensor.

10. The aftertreatment system of claim 9 , wherein the vertical height is a vertical distance between the pressure sensor and the injector.

11. The aftertreatment system of claim 9 , wherein the data received from the pressure sensor includes a first measurement indicative of a first pressure within the supply conduit when the pump is operating and a second measurement indicative of a second pressure within the supply conduit when the pump is not operating.

12. The aftertreatment system of claim 11 , further comprising a return conduit fluidly coupling the injector and the tank, wherein the second measurement is taken with the return conduit empty of the fluid.

13. The aftertreatment system of claim 11 , further comprising a return conduit fluidly coupling the injector and the tank, wherein the second measurement is taken with the return conduit filled with the fluid.

14. The aftertreatment system of claim 8 , wherein the fluid includes urea.

15. The aftertreatment system of claim 8 , wherein the fluid includes a hydrocarbon fluid.

16. A method of controlling a pump of a fluid injection system for an exhaust aftertreatment system comprising:

operating the pump to achieve a stable target pressure in a supply conduit connecting the pump and an injector of the fluid injection system;

shutting off the pump after the stable target pressure is achieved;

allowing a fluid pressure within the supply conduit to stabilize after shutting off the pump;

acquiring a first fluid pressure measurement within the supply conduit after the fluid pressure is allowed to stabilize to account for a pressure head that exists due to a vertical distance between the injector and a location at which the first fluid pressure measurement is made;

operating the pump after acquiring the first fluid pressure;

and

controlling operation of the pump based on the first and second fluid pressure measurement to account for the pressure head existing in the supply conduit when the pump is off.

17. The method of claim 16 , further including acquiring a second fluid pressure measurement within the supply conduit during the operation of the pump after acquiring the first fluid pressure, wherein controlling operation of the pump based on the first and second fluid pressure measurements includes adding the first fluid pressure measurement to the second fluid pressure measurement.

18. The method of claim 16 , wherein the fluid injection system includes a return conduit fluidly coupling the injector with a tank, wherein the first fluid pressure measurement is acquired with the return conduit empty of injection fluid.

19. The method of claim 16 , wherein the fluid injection system includes a return conduit fluidly coupling the injector with a tank, wherein the first fluid pressure measurement is acquired with the return conduit filled with injection fluid.