Fuel pressure control strategy at engine shutdown
View Patent ↗A fuel system control method may include determining when an engine transitions from an engine on condition to an engine off condition. The method further includes determining a first fuel pressure in a fuel system of the engine a predetermined time after the determined engine off condition. A fuel injector of the fuel system may be actuated during the engine off condition when the first determined fuel pressure is above a first predetermined pressure limit to bleed fuel from the fuel system and reduce pressure within the fuel system.
1. A method comprising:
determining when an engine transitions from an engine on condition to an engine off condition;
determining a first fuel pressure in a direct injection fuel system of the engine a predetermined time after the determined engine off condition; and
actuating a fuel injector of the direct injection fuel system during the engine off condition when the first determined fuel pressure is above a first predetermined pressure limit to bleed fuel from the direct injection fuel system and reduce pressure within the direct injection fuel system to a pressure below the first predetermined pressure limit.
2. The method of claim 1 , wherein the first fuel pressure is determined in a fuel rail of the direct injection fuel system.
3. The method of claim 2 , wherein the direct injection fuel system operates at a fuel pressure of at least 30 megapascal (MPa) within the fuel rail during the engine on condition.
4. The method of claim 3 , wherein the first predetermined pressure limit is less than or equal to 5 MPa.
5. The method of claim 1 , wherein the actuating includes actuating the fuel injector for at least 100 microseconds.
6. The method of claim 1 , further comprising determining a second fuel pressure in the direct injection fuel system after the actuating and indicating a system fault when the second fuel pressure is above a second predetermined pressure limit.
7. The method of claim 6 , wherein the system fault indicates a faulty pressure sensor.
8. The method of claim 6 , wherein the second predetermined pressure limit is equal to the first predetermined pressure limit.
9. The method of claim 1 , wherein the predetermined time and the first predetermined pressure limit are empirically determined based on a fuel leak rate through the fuel injector when the fuel injector is in a non-actuated state.
10. A method comprising:
determining when an engine transitions from an engine on condition to an engine off condition;
determining a first fuel pressure in a direct injection fuel system of the engine a predetermined time after the determined engine off condition;
actuating a fuel injector of the direct injection fuel system during the engine off condition when the first determined fuel pressure is above a first predetermined pressure limit to bleed fuel from the direct injection fuel system and reduce pressure within the direct injection fuel system to a pressure below the first predetermined pressure limit;
determining a second fuel pressure in the direct injection fuel system after the actuating; and
indicating a system fault when the second fuel pressure is above a second predetermined pressure limit.
11. The method of claim 10 , wherein the predetermined time and the first and second predetermined pressure limits are empirically determined based on a fuel leak rate through the fuel injector when the fuel injector is in a non-actuated state.
12. A control module comprising:
an engine operating condition evaluation module that determines when an engine transitions from an on condition to an off condition;
a fuel pressure determination module in communication with the engine operating condition evaluation module that determines a first fuel pressure in a direct injection fuel system of the engine a predetermined time after the determined engine off condition; and
a fuel injector actuation module in communication with the fuel pressure determination module that actuates a fuel injector of the direct injection fuel system during the engine off condition when the first determined fuel pressure is above a first predetermined pressure limit to bleed fuel from the direct injection fuel system and reduce pressure within the direct injection fuel system to a pressure below the first predetermined pressure limit.
13. The control module of claim 12 , wherein the fuel pressure determination module determines the fuel pressure within a fuel rail of the direct injection fuel system.
14. The control module of claim 13 , wherein the direct injection fuel system operates at a fuel pressure of at least 30 megapascal (MPa) within the fuel rail during the engine on condition.
15. The control module of claim 14 , wherein the first predetermined pressure limit is less than or equal to 5 MPa.
16. The control module of claim 12 , wherein the fuel injector actuation module actuates the fuel injector for at least 100 microseconds.
17. The control module of claim 12 , further comprising a fuel system fault determination module in communication with the fuel pressure determination module, the fuel pressure determination module determining a second fuel pressure in the direct injection fuel system after the actuating and the direct injection fuel system fault determination module indicating a system fault when the second fuel pressure is above a second predetermined pressure limit.
18. The control module of claim 17 , wherein the system fault indicates a faulty pressure sensor.
19. The control module of claim 18 , wherein the second predetermined pressure limit is equal to the first predetermined pressure limit.
20. The control module of claim 12 , wherein the predetermined time and the first predetermined pressure limit are empirically determined based on a fuel leak rate through the fuel injector when the fuel injector is in a non-actuated state.