Systems and methods for reducing rail pressure in a common rail fuel system
Methods and systems, using a controller ( 20 ), for performing fuel pressure control operation of an engine ( 12 ) having at least one cylinder ( 16 ) is disclosed. The controller ( 20 ) includes a fuel system control unit ( 42 ) configured to control a fuel pressure applied to at least one injector ( 18 ) of the engine ( 12 ) during a motoring condition period ( 412 ) based on a commanded pulse train duration ( 410 ). During the motoring condition period ( 412 ), no combustion occurs in the at least one cylinder ( 16 ) of the engine ( 12 ). The commanded pulse train duration is a time period during which the at least one injector ( 18 ) of the engine ( 12 ) is activated for a drain operation. The fuel system control unit ( 42 ) is configured to command the at least one injector ( 18 ), for the commanded pulse train duration during the motoring condition period ( 412 ), to release fuel from the at least one injector ( 18 ) without injecting the fuel into the at least one cylinder ( 16 ) of the engine ( 12 ).
1. A system for performing fuel pressure control operation of an engine ( 12 ) having at least one cylinder ( 16 ) comprising:
a controller ( 20 ) including a fuel system control unit ( 42 ) configured to control a fuel pressure applied to at least one injector ( 18 ) of the engine ( 12 ) during a motoring condition period ( 412 ) based on a commanded pulse train duration ( 410 ), the motoring condition period ( 412 ) during which no combustion occurs in the at least one cylinder ( 16 ) of the engine ( 12 ), the commanded pulse train duration being a time period ( 410 ) during which the at least one injector ( 18 ) of the engine ( 12 ) is activated for operation,
wherein the fuel system control unit ( 42 ) is configured to command the at least one injector ( 18 ), for the commanded pulse train duration during the motoring condition period ( 412 ), to release fuel from the at least one injector ( 18 ) without injecting the fuel into the at least one cylinder ( 16 ) of the engine ( 12 ).
2. The system of claim 1 , wherein the fuel system control unit ( 42 ) is configured to determine the commanded pulse-train duration based on a critical injector activation time.
3. The system of claim 2 , wherein the critical injector activation time represents a maximum commanded on-time period applied to the at least one injector ( 18 ) to achieve a maximum fuel drain amount from the at least one injector ( 18 ) without delivering the fuel to the at least one cylinder ( 16 ) of the engine ( 12 ).
4. The system of claim 2 , wherein the fuel system control unit ( 42 ) is configured to command the at least one injector ( 18 ) for a commanded on-time period that is less than the critical injector activation time.
5. The system of claim 2 , wherein the fuel system control unit ( 42 ) is configured to command the at least one injector ( 18 ) for a commanded on-time period that is greater than or equal to the critical injector activation time.
6. The system of claim 2 , wherein the fuel system control unit ( 42 ) is configured to generate at least one drain pulse ( 408 ) applied to the at least one injector ( 18 ) during the motoring condition period ( 412 ) based on the critical injector activation time.
7. The system of claim 6 , wherein the at least one drain pulse ( 408 ) has a commanded on-time period that is less than the critical injector activation time.
8. The system of claim 6 , wherein the fuel system control unit ( 42 ) is configured to command two or more injectors ( 18 ) simultaneously using the at least one drain pulse ( 408 ) to increase fuel drainage from the engine ( 12 ).
9. The system of claim 6 , wherein the fuel system control unit ( 42 ) is configured to generate at least one test pulse ( 416 ) applied to the at least one injector ( 18 ) during the motoring condition period ( 412 ) based on the critical injector activation time.
10. The system of claim 9 , wherein the at least one test pulse ( 416 ) has a commanded on-time period that is greater than or equal to the critical injector activation time.
11. A method of performing fuel pressure control operation of an engine ( 12 ) having at least one cylinder ( 16 ) comprising:
receiving a signal indicating that no fuel is delivered to the at least one cylinder ( 16 ) of the engine ( 12 );
detecting a motoring condition based on the received signal;
controlling a fuel pressure applied to at least one injector ( 18 ) of the engine ( 12 ) in the motoring condition based on a commanded pulse train duration ( 410 ); and
commanding the at least one injector ( 18 ), for the commanded pulse train duration, to release fuel from the at least one injector ( 18 ) without injecting the fuel into the at least one cylinder ( 16 ) of the engine ( 12 ).
12. The method of claim 11 , further comprising determining the commanded pulse train duration based on a critical injector activation time.
13. The method of claim 12 , further comprising calculating the critical injector activation time that represents a maximum commanded on-time period applied to the at least one injector ( 18 ) to achieve a maximum fuel drain amount from the at least one injector ( 18 ) without delivering the fuel to the at least one cylinder ( 16 ) of the engine ( 12 ).
14. The method of claim 12 , further comprising commanding the at least one injector ( 18 ) for a commanded on-time period that is less than the critical injector activation time.
15. The method of claim 12 , further comprising commanding the at least one injector ( 18 ) for a commanded on-time period that is greater than or equal to the critical injector activation time.
16. The method of claim 12 , further comprising generating at least one drain pulse ( 408 ) applied to the at least one injector ( 18 ) of the engine ( 12 ) in the motoring condition based on the critical injector activation time.
17. The method of claim 16 , further comprising using the at least one drain pulse ( 408 ) having a commanded on-time period that is less than the critical injector activation time.
18. The method of claim 16 , further comprising commanding two or more injectors ( 18 ) simultaneously using the at least one drain pulse ( 408 ) to increase fuel drainage from the engine ( 12 ).
19. The method of claim 16 , further comprising generating at least one test pulse ( 416 ) applied to the at least one injector ( 18 ) of the engine ( 12 ) in the motoring condition based on the critical injector activation time.
20. The method of claim 19 , further comprising using the at least one test pulse ( 416 ) having a commanded on-time period that is greater than or equal to the critical injector activation time.