Individual timing and injection fuel metering system

• US 5,441,027 A
• Filed: 03/10/1994
• Issued: 08/15/1995
• Est. Priority Date: 05/24/1993
• Status: Expired due to Term

• Current Assignee: Cummins Incorporated
• Original Assignee: Cummins Incorporated
• Inventors: Buchanon, David L., Peters, Lester L., Tarr, Yul J., Perr, Julius P.
• Primary Examiner(s): Moulis, Thomas N.
• Application Number:
  US08/208,365
• Time in Patent Office: 523 Days
• Field of Search: 123/446, 123/502, 123/456, 123/500, 123/501, 123/510, 123/481
• US Class Current: 123/446
• CPC Class Codes: F02M 57/02 Injectors structurally combined with fuel-injection pumps
• CPC Class Codes: F02M 57/021 the injector being of valveless type, e.g. the pump piston co-operating with a conical seat of an injection nozzle at the end of the pumping stroke
• CPC Class Codes: F02M 57/024 with hydraulic link for varying the piston stroke
• CPC Class Codes: F02M 57/025 hydraulic, e.g. with pressure amplification
• CPC Class Codes: F02M 57/026 Construction details of pressure amplifiers, e.g. fuel passages or check valves arranged in the intensifier piston or head, particular diameter relationships, stop members, arrangement of ports or conduits
• CPC Class Codes: F02M 59/105 hydraulic drive F02M59/32 takes precedence
• CPC Class Codes: F02M 59/366 Valves being actuated electrically

Abstract

A metering system is provided which controls the amount of fuel supplied to the combustion chambers of a multi-cylinder internal combustion engine comprising a fuel pump for supplying fuel at low pressure to a first and a second group of unit fuel injectors, a first solenoid-operated fuel control valve controlling the flow of fuel to the first set of injectors and a second solenoid-operated fuel control valve controlling the flow of fuel to the second set of injectors. The system may also include first and second solenoid-operated timing fluid control valves associated with the first and the second group of injectors, respectively. The injectors are capable of being in the fuel receiving mode, establishing a metering period, and the timing receiving mode, establishing a timing period, at the same time to increase the amount of time available for metering both timing fluid and fuel. By grouping the various injectors based on the order of injection so that the injectors from each group are placed in the injection mode in spaced periods throughout each cycle of the engine, e.g. injectors from other groups injecting in the period of time between each injection mode, the system can be designed to permit longer metering and timing periods.

Claims

1. A metering system for controlling the amount of fuel supplied to the combustion chambers of a multi-cylinder internal combustion engine, comprising:

a fluid supply means for supplying fuel at low supply pressure, said fluid supply means including first and second fuel supply paths;

a first set of unit injectors for receiving fuel from said fluid supply means at the low supply pressure and for injecting the fuel at relatively high pressure into respective combustion chambers of the engine, each injector of said first set adapted to be placed in a fuel receiving mode for receiving fuel from said fluid supply means, only one unit injector from said first set of unit injectors being placed in said fuel receiving mode at any given time;

a first electromagnetic fuel control valve positioned in said first fuel supply path between said fluid supply means and said first set of unit injectors for controlling the flow of fuel to said first set of unit injectors;

a second set of unit injectors for receiving fuel from said fluid supply means at the low pressure and for injecting the fuel at relatively high pressure into respective combustion chambers of the engine, each injector of said second set adapted to be placed in a fuel receiving mode for receiving fuel from said fluid supply means, only one unit injector from said second set of unit injectors being placed in said fuel receiving mode at any given time; and

a second electromagnetic fuel control valve positioned in said second fuel supply path between said fluid supply means and said second set of unit injectors for controlling the flow of fuel to said second set of unit injectors.

2. The metering system of claim 1, wherein said fluid supply means includes first and second timing fluid supply paths for supplying timing fluid to said first and said second set of unit injectors, respectively, each unit injector of said first and said second set of unit injectors adapted to receive timing fluid from said fluid supply means for controlling the timing of injection, further including a first electromagnetic timing fluid control valve positioned in said first timing fluid supply path between said fluid supply means and said first set of unit injectors for controlling the flow of timing fluid to said first set of unit injectors, and a second electromagnetic timing fluid control valve positioned in said second timing fluid supply path between said fluid supply means and said second set of unit injectors for controlling the flow of timing fluid to said second set of unit injectors, wherein at any given time during the operation of the unit injectors only one unit injector from each of said first and said second set of unit injectors is in a timing fluid receiving mode for receiving timing fluid from said fluid supply means.

3. The metering system of claim 2, wherein said one unit injector is capable of being in said fuel receiving mode and said timing fluid receiving mode at the same time.

4. The metering system of claim 2, wherein each unit injector includes an injector body containing an injector cavity, a fluid timing circuit communicating with one of said first and said second timing fluid supply paths, and a fuel metering circuit communicating with one of said first and said second fuel supply paths, said fluid timing circuit and said fuel metering circuit communicating with said injector cavity, and an injection orifice formed in one end of said injector body and further including a plunger means mounted for reciprocal movement within said injector cavity, said plunger means comprising inner and outer plunger sections, a variable volume timing chamber being formed in said injector cavity between said inner and outer plunger sections and a variable volume fuel metering chamber being formed in said injector cavity between said inner plunger section and said injection orifice and wherein said plunger means is operable to be placed in said fuel receiving mode establishing a metering period during which fuel may flow through said metering circuit into said metering chamber, is operable to be placed in said timing fluid receiving mode establishing a timing period during which timing fluid may flow through said fluid timing circuit into said timing chamber, and is operable to be placed in an injection mode in which fluid flow through both circuits to both of said chambers is blocked thereby for producing injection of the fuel in said metering chamber through said injection orifice.

5. The metering system of claim 4, wherein at least a portion of said metering period of each unit injector occurs during said timing period of the same unit injector.

6. The metering system of claim 4, wherein said first and said second electromagnetic fuel control valves are each movable between an open position wherein fuel may flow therethrough to said metering chamber of a unit injector of said first set of unit fuel injectors and said second set of unit fuel injectors, respectively, during said metering period and a closed position wherein fuel is blocked from flowing therethrough to said metering chamber, and wherein said first and said second electromagnetic timing fluid control valves are each movable between an open position wherein timing fluid may flow therethrough to said timing chamber of a unit injector of said first set of unit fuel injectors and said second set of unit fuel injectors, respectively, during said timing period and a closed position wherein fluid is blocked from flowing therethrough to said timing chamber.

7. The metering system of claim 6, wherein each of said first and said second electromagnetic fuel control valves and each of said first and said second electromagnetic timing fluid control valves is movable from said closed position to said open position and from said open position to said closed position within said metering period and said timing period, respectively, to define a fuel metering event and a timing fluid metering event, respectively.

8. The metering system of claim 7, wherein said plunger means is operable to move through periodic injection Strokes in which said plunger means moves inwardly in said injector cavity toward said injection orifice for each cycle of the engine causing fuel to be expelled from said injector cavity through said injection orifice to the combustion chamber, said fuel metering event and said timing fluid metering event occurring only between said periodic injection strokes.

9. The metering system of claim 7, wherein said plunger means is operable to move through a metering stroke in which said plunger means moves outwardly in said injector cavity away from said injection orifice, said fuel metering event and said timing fluid metering event occurring only during said metering stroke.

10. The metering system of claim 1, wherein each unit injector of said first and said second set of unit injectors includes an injector body containing an injector cavity, a fluid timing circuit for receiving timing fluid from said fluid supply means, a fuel metering circuit communicating with one of said first and second fuel supply paths, a plunger means mounted for reciprocal movement within said injector cavity and an injection orifice formed in said injector body at one end of said injector cavity, a variable volume metering chamber being formed in said injector cavity adjacent a first end of said plunger means between said plunger means and said injection orifice and a variable volume timing chamber being formed in said injector cavity adjacent a second end of said plunger means opposite said first face, said timing chamber of each injector adapted to receive timing fluid from said fluid supply means, further including an electromagnetic timing fluid control valve positioned in said fluid timing circuit between said timing chamber and said fluid supply means for controlling the flow of timing fluid to said timing chamber, wherein said electromagnetic timing fluid control valve is movable between an open position wherein timing fluid may flow therethrough to said timing chamber and a drain position wherein timing fluid is drained therethrough from said timing chamber to define a timing event during which the timing fluid at a predetermined pressure forces said plunger means toward said metering chamber for producing injection of the fuel in said metering chamber through said injection orifice.

11. The metering system of claim 10, wherein the timing fluid acts on said second end of said plunger means to force said plunger means toward said metering chamber, said second end having an effective cross-sectional area greater than the effective cross-sectional area of said first end of said plunger means.

12. The metering system of claim 4, wherein said fuel metering circuit includes a fuel supply port formed in said injector body and a spring-loaded check valve positioned upstream of said supply port for permitting fuel to flow into said metering chamber during said metering period and for preventing the flow of fuel from said metering chamber during the period of injector operation when the metered fuel is injected.

13. The metering system of claim 12, wherein said inner plunger section reciprocates adjacent to said injection orifice and said metering chamber is positioned adjacent said injection orifice.

14. The metering system of claim 2, wherein said fluid supply means supplies timing fluid to said first and said second timing fluid supply paths at a substantially constant pressure and supplies fuel to said first and said second fuel supply paths at a substantially constant pressure.

15. The metering system of claim 2, wherein said fluid supply means includes a fuel pump for providing fuel to each of said first and said second fuel supply paths and to each of said first and said second timing fluid supply paths.

16. The metering system of claim 15, wherein said fuel pump includes a pressure regulator for varying the fuel supply pressure based on engine operating conditions.

17. The metering system of claim 15, further including at least one flow control valve positioned downstream of said fuel pump for providing a fixed fuel flow rate independent of fuel pressures upstream and downstream of said at least one flow control valve.

18. The metering system of claim 17, wherein said at least one flow control valve includes four flow control valves, each of said four flow Control valves positioned adjacent one of said electromagnetic valves.

19. The metering system of claim 1, wherein each injector of said first and said second set of injectors is adapted to be placed in a fuel injection mode for producing injection of the fuel into respective combustion chambers of the engine, said injection mode of each injector in said first set of injectors occurring after the injection mode of an injector of said second set of injectors.

20. The metering system of claim 2, wherein said first and second timing fluid supply paths are fluidically separate from said first and second fuel supply paths.

21. The metering system of claim 20, wherein said fluid supply means includes a lube oil supply pump for supplying lube oil to said timing fluid supply paths and a fuel supply pump for supplying fuel to said first and second fuel supply paths.

22. A metering system for metering and timing of fuel injection into the combustion chambers of a multi-cylinder internal combustion engine, comprising:

a fluid supply means for supplying fuel and timing fluid at a low supply pressure, said fluid supply means including a timing fluid common rail and a fuel common rail;

one or more unit injectors positioned adjacent said common rails for receiving fuel at the low supply pressure and for injecting the fuel at relatively high pressure into respective combustion chambers of the engine, each of said one or more injectors including an injector body containing an injector cavity, a fluid timing circuit communicating with said timing fluid common rail, a fuel metering circuit communicating with said fuel common rail, and an injection orifice formed in one end of said injector body and further including a plunger means mounted for reciprocal movement in said injector cavity, said plunger means including inner and outer plunger sections, a variable volume timing chamber being formed in said injector cavity between said inner and outer plunger sections and a variable volume fuel metering chamber being formed in said injector cavity between said inner plunger section and an end of the injector cavity;

an electromagnetic timing fluid control valve positioned in said timing fluid common rail for controlling the flow of fuel to said timing chamber, said electromagnetic timing fluid control valve being movable between an open position wherein timing fluid may flow therethrough to said timing chamber and a closed position wherein fluid is blocked from flowing therethrough to said timing chamber; and

an electromagnetic fuel control valve positioned in said fuel common rail for controlling the flow of fuel to said metering chamber, said electromagnetic fuel control valve being movable between an open position wherein fuel may flow therethrough to said metering chamber and a closed position wherein fuel is blocked from flowing therethrough to said metering chamber, wherein said electromagnetic fuel control valve and said electromagnetic timing fluid control valve are each movable from said closed position to said open position and from said open position to said closed position to define a fuel metering event and a timing fluid metering event, respectively, during which a predetermined quantity of fuel and timing fluid, respectively, are metered into said metering chamber and said timing chamber, respectively.

23. The metering system of claim 22, wherein said plunger means is operable to be placed in a fuel receiving mode establishing a metering period during which fuel may flow through said metering circuit into said metering chamber, said plunger means operable to be placed in a timing fluid receiving mode establishing a timing period during which timing fluid may flow through said timing fluid common rail into said timing chamber, and said plunger means operable to be placed in an injection mode in which fluid flow through both said circuits to both of said chambers is blocked thereby for producing injection of the fuel in said metering chamber through said injection orifice.

24. The metering system of claim 23, wherein at least a portion of said metering period of each of said one or more injectors occurs during said timing period of the same injector.

25. The metering system of claim 24, wherein said plunger means is operable to move through periodic injection strokes in which said plunger means moves inwardly in said injector cavity toward the said injection orifice for each cycle of the engine causing fuel to be expelled from said injector cavity through said injection orifice to the combustion chamber, said fuel metering event and said timing fluid metering event occurring only between said periodic injection strokes.

26. The metering system of claim 24, wherein said plunger means is operable to move through a metering stroke in which said plunger means moves outwardly in said injector cavity away from said injection orifice, said fuel metering event and said timing fluid metering event occurring only during said metering stroke.

27. The metering system of claim 22, wherein said fluid supply means includes a fuel supply pump for supplying both fuel and a timing fluid to said one or more injectors.

28. The metering system of claim 22, wherein said electromagnetic timing fluid control valve is movable between an open position wherein timing fluid may flow therethrough to said timing chamber and a closed position wherein fluid is blocked from flowing therethrough to said timing chamber to define a timing event during which the timing fluid at a predetermined pressure forces said plunger means toward said metering chamber for producing injection of the fuel in said metering chamber through said injection orifice.

29. The metering system of claim 22, wherein said fuel metering circuit each includes a fuel supply port formed in said injector body and a spring-loaded check valve positioned upstream of said supply port for permitting fuel into said metering chamber during said metering period and for preventing the flow of fuel from said metering chamber during the period of injector operation when the metered fuel is injected.

30. The metering system of claim 29, wherein said inner plunger section reciprocates adjacent to said injection orifice and said metering chamber is positioned adjacent said injection orifice.

31. The metering system of claim 27, wherein said fluid supply means supplies timing fluid to said timing fluid common rail at a substantially constant pressure and supplies fuel to said fuel common rail at a substantially constant pressure.

32. The metering system of claim 27, wherein said fuel pump includes a pressure regulator for varying the fuel supply pressure based on engine operating conditions.

33. The metering system of claim 27, further including at least one flow control valve positioned downstream of said fuel pump for providing a fixed fuel flow rate independent of upstream and downstream fuel pressures.

34. The metering system of claim 33, wherein said at least one flow control valve includes two flow control valves, each of said two flow control valves positioned adjacent one of said electromagnetic valves.

35. The metering system of claim 22, wherein said timing fluid common rail and said fluid timing circuit is fluidically separate from said fuel common rail and said fuel metering circuit.

36. The metering system of claim 35, wherein said fluid supply means includes a lube oil supply pump for supplying lube oil to said timing fluid common rail and a fuel supply pump for supplying fuel to said fuel common rail.