High Pressure Oil Limit Based on Fuel Level To Protect Fuel Injectors

• US 20100030452A1
• Filed: 08/01/2008
• Published: 02/04/2010
• Est. Priority Date: 08/01/2008
• Status: Active Grant

• Current Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Original Assignee: International Engine Intellectual Property Company, LLC (Volkswagen AG)
• Inventors: Rodriguez, Rogelio, Beyene, Michael
• Granted Patent: US 7,702,449 B2
• Time in Patent Office: Days
• US Class Current: 701/104
• CPC Class Codes: F02D 2250/02 Fuel evaporation in fuel rails, e.g. in common rails
• CPC Class Codes: F02D 2250/31 Control of the fuel pressure
• CPC Class Codes: F02D 33/003 Controlling the feeding of liquid fuel from storage containers to carburettors or fuel-injection apparatus control of electrical fuel pumps F02D41/3082, controlling fuel flow to a common rail F02D41/3845; Failure or leakage prevention; Diagnosis or detection of failure; Arrangement of sensors in the fuel system; Electric wiring; Electrostatic discharge
• CPC Class Codes: F02D 41/021 Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/221 relating to the failure of actuators or electrically driven elements
• CPC Class Codes: F02D 41/3836 Controlling the fuel pressure
• CPC Class Codes: F02D 41/3854 with elements in the low pressure part, e.g. low pressure pump
• CPC Class Codes: F02D 41/40 with means for controlling injection timing or duration
• CPC Class Codes: F02M 57/025 hydraulic, e.g. with pressure amplification
• CPC Class Codes: F02M 63/023 Means for varying pressure in common rails pressure control F02D41/3845

Abstract

A first fuel value (FL_Signal) indicative of the quantity of fuel presently in a fuel tank (34) and a second fuel value (FL_LOW_THLD) representing a quantity of fuel in the tank at which a maximum Injection Control Pressure (ICP) limit should be changed are processed by a processor (22). When the result of the processing discloses that the second fuel value is less than the first fuel value, the maximum ICP limit is reduced from a greater value (ICPC_NORMAL_LMX) to a lesser value (ICPC_FL_LMX).

Claims

1. An internal combustion engine comprising:

a control system;

a fuel system that draws liquid fuel from a fuel tank to charge fuel injectors that when actuated by the control system force fuel charges into engine combustion chambers using hydraulic fluid at injection control pressure (ICP); and

the control system comprising a processor for executing an ICP control strategy, wherein the strategy comprises processing a first fuel value indicative of the quantity of fuel presently in the tank and a second fuel value representing a quantity of fuel in the tank at which a maximum ICP limit set by the ICP control strategy should be changed, and when the result of the processing discloses that the second fuel value is less than the first fuel value, execution of the ICP control strategy reduces the maximum ICP limit from a greater value to a lesser value.

2. An engine as set forth in claim 1 wherein execution of the ICP control strategy conditions reduction of the maximum ICP limit from the greater value to the lesser value on the second fuel value being continuously less than the first fuel value for a defined length of time.

3. An engine as set forth in claim 1 wherein execution of the ICP control strategy restores the maximum ICP limit from the lesser value to the greater value when the result of the processing discloses that the second fuel value ceases to be less than the first fuel value.

4. An engine as set forth in claim 3 wherein execution of the ICP control strategy conditions restoration of the maximum ICP limit from the lesser value to the greater value on the second fuel value continuously ceasing to be less than the first fuel value for a defined length of time.

5. An engine as set forth in claim 1 comprising a switch function having inputs whose values correspond respectively to the greater and the lesser values of the maximum ICP limit, and wherein the switch function is controlled by the result of processing the first and second fuel values.

6. A fuel system and a control system for an internal combustion engine:

wherein the fuel system draws liquid fuel from a fuel tank to charge fuel injectors that when actuated by the control system force fuel charges into engine combustion chambers using hydraulic fluid at injection control pressure (ICP); and

wherein the control system comprises a processor for executing an ICP control strategy that comprises processing a first fuel value indicative of the quantity of fuel presently in the tank and a second fuel value representing a quantity of fuel in the tank at which a maximum ICP limit set by the ICP control strategy should be changed, and when the result of the processing discloses that the second fuel value is less than the first fuel value, causing the maximum ICP limit to be reduced from a greater value to a lesser value.

7. A fuel system and a control system as set forth in claim 6 wherein execution of the ICP control strategy conditions reduction of the maximum ICP limit from the greater value to the lesser value on the second fuel value being continuously less than the first fuel value for a defined length of time.

8. A fuel system and a control system as set forth in claim 6 wherein execution of the ICP control strategy restores the maximum ICP limit from the lesser value to the greater value when the result of the processing discloses that the second fuel value ceases to be less than the first fuel value.

9. A fuel system and a control system as set forth in claim 8 wherein execution of the ICP control strategy conditions restoration of the maximum ICP limit from the lesser value to the greater value on the second fuel value continuously ceasing to be less than the first fuel value for a defined length of time.

10. A fuel system and a control system as set forth in claim 6 comprising a switch function having inputs whose values correspond respectively to the greater and the lesser values of the maximum ICP limit, and wherein the switch function is controlled by the result of processing the first and second fuel values.

11. A method for control of injection control pressure (ICP) that is used to force the injection of fuel into an engine combustion chamber comprising:

processing a first fuel value indicative of the quantity of fuel presently in a fuel tank and a second fuel value representing a quantity of fuel in the tank at which a maximum ICP limit should be changed, and when the result of the processing discloses that the second fuel value is less than the first fuel value, causing the maximum ICP limit to be reduced from a greater value to a lesser value.

12. A method as set forth in claim 11 comprising conditioning reduction of the maximum ICP limit from the greater value to the lesser value on the second fuel value being continuously less than the first fuel value for a defined length of time.

13. A method as set forth in claim 11 comprising restoring the maximum ICP limit from the lesser value to the greater value when the result of the processing discloses that the second fuel value ceases to be less than the first fuel value.

14. A method as set forth in claim 13 comprising conditioning restoration of the maximum ICP limit from the lesser value to the greater value on the second fuel value continuously ceasing to be less than the first fuel value for a defined length of time.

15. A method as set forth in claim 11 comprising controlling a switch function by the result of processing the first and second fuel values to cause the switch function to pass one of the greater and the lesser values of the maximum ICP limit to the exclusion of the other based on the result of processing the first and second fuel values.