MULTI-LEVEL SKIP FIRE

• US 20160131058A1
• Filed: 10/21/2015
• Published: 05/12/2016
• Est. Priority Date: 11/10/2014
• Status: Active Grant

• Current Assignee: Tula Technology, Incorporated
• Original Assignee: Tula Technology, Incorporated
• Inventors: YOUNKINS, Matthew A., SERRANO, Louis J.
• Granted Patent: US 9,399,964 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: F01L 1/047 Camshafts
• CPC Class Codes: F02D 11/02 characterised by hand, foot, or like operator controlled initiation means
• CPC Class Codes: F02D 13/0223 Variable control of the intake valves only
• CPC Class Codes: F02D 13/0273 Multiple actuations of a valve within an engine cycle
• CPC Class Codes: F02D 13/06 Cutting-out cylinders
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 2041/001 for engines with variable valve actuation
• CPC Class Codes: F02D 2041/0012 with selective deactivation of cylinders
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 41/0002 Controlling intake air
• CPC Class Codes: F02D 41/008 Controlling each cylinder individually
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/04 Introducing corrections for particular operating conditions F02D41/14 takes precedence
• CPC Class Codes: F02D 41/107 and deceleration
• CPC Class Codes: F02D 41/123 the fuel injection being cut-off
• CPC Class Codes: F02D 41/26 using computer, e.g. microprocessor
• CPC Class Codes: F02P 5/145 using electrical means
• CPC Class Codes: F02P 5/1502 using one central computing unit
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In one aspect, a method for controlling operation of an internal combustion engine is described. The engine is operated in a skip fire manner such that selected skipped working cycles are skipped and selected active working cycles are fired to deliver a desired engine output. A particular level of torque output is selected for each of the fired working chambers. Various methods, arrangements and systems related to the above method are also described.

Claims

1. A method of controlling the operation of an internal combustion engine having a plurality of working chambers to deliver a desired output, wherein each working chamber has at least one intake valve that is cam-actuated and at least one exhaust valve, the method comprising:

operating the engine in a skip fire manner that skips selected skipped working cycles and fires selected active working cycles to deliver a desired engine output, wherein decisions whether to fire or skip each working cycle are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and

selecting a high or low torque output on the fired working chambers wherein decisions whether to use a high or low torque output are dynamically determined during operation of the engine on a firing opportunity by firing opportunity basis; and

adjusting air charge for the fired working chambers based on whether the high or low torque output was selected on the fired working chambers.

2. A method as recited in claim 1 wherein the air charge is adjusted to generate high or low torque output by independently controlling at least two intake valves in each of the fired working chambers.

3. A method as recited in claim 1, further comprising:

deactivating skipped working chambers during selected skipped working cycles to thereby prevent pumping air through the skipped working chambers during the selected skipped working cycles.

4. A method as recited in claim 1 wherein all of the valves are actuated by one or more cam lobes coupled with one or more camshafts.

5. A method as recited in claim 1 further comprising:

generating a skip fire firing sequence that indicates for each fire, whether the fire involves using a high or low torque output; and

operating the engine based on the skip fire firing sequence.

6. A method as recited in claim 1 further comprising:

determining a level fraction and a firing fraction wherein the level fraction helps indicate a ratio of high or low torque output fires relative to a total number of fires including the high torque output and low torque output fires; and

operating the engine in a skip fire manner based on the level fraction and the firing fraction.

7. A method as recited in claim 1 wherein the selection of the high or low torque output on the fired working chambers is determined at least in part using a sigma delta converter.

8. A method as recited in claim 1 wherein the selection of the high or low torque output is based on one or more of a lookup table and a state machine.

9. A method as recited in claim 1 wherein each of the working chambers includes a first intake valve and a second intake valve, the method further comprising:

while operating the engine in a skip fire manner and during a selected working cycle, opening and closing the first and second intake valves based on different timing cycles.

10. A method as recited in claim 9 wherein the first intake valve is operated based on an Atkinson cycle and the second intake valve is operated based on an Otto cycle.

11. A method as recited in claim 1 wherein:

the firing of selected active working cycles involves firing working chambers at the high or low torque output based on whether high or low torque output was selected on the fired working chambers;

each fired working chamber includes a first intake valve and a second intake valve;

when a fired working chamber is fired at a high torque output, the first and second intake valves of the fired working chamber are independently controlled based on a high torque valve control scheme; and

when a fired working chamber is fired at a low torque output, the first and second intake valves of the fired working chamber are independently controlled based on a low torque valve control scheme, which is different from the high torque valve control scheme.

12. A method as recited in claim 11 wherein:

the high torque valve control scheme involves delivering air through the first and second intake valves during a selected working cycle; and

the low torque valve control scheme involves not allowing air through the first intake valve during a selected working cycle.

13. A method as recited in claim 10 wherein:

the high torque valve control scheme involves delivering air through the first intake valve and not the second intake valve during a selected working cycle;

the high torque valve control scheme further involves operating the first intake valve based on an Otto cycle during the selected working cycle;

the low torque valve control scheme involves delivering air through the first and the second intake valves during a selected working cycle; and

the low torque valve control scheme further involves operating the first intake valve based on an Otto cycle during the selected working cycle and operating the second intake valve based on a Late Intake Valve Closure (LIVC) Atkinson cycle during the selected working cycle.

14. A method as recited in claim 1 further comprising:

detecting a knock in a working chamber of the engine; and

in response to the detection, requiring that one or more working chambers be fired at the low torque output and not the high torque output; and

operating the engine in a skip fire manner based on the requirement.

15. A method as recited in claim 1 further comprising:

detecting a condition that is one of

     1) vehicle deceleration and coasting; and

     2) stopping of the engine using a start/stop feature;

detecting that engine torque has been requested;

in response to the detection operations, requiring that one or more selected working chambers not be fired at the high torque output; and

operating the engine in a skip fire manner based on the requirement.

16. A method as recited in claim 1, further comprising:

assigning a window to a target firing opportunity for a target working chamber;

determining whether a high or low torque output is selected on one or more of the working chambers;

firing the target working chamber during the window;

measuring an engine parameter during the window; and

determining whether an engine problem exists based at least in part on the torque output determination and the engine parameter measurement.

17. A method as recited in claim 1 wherein:

the engine includes a first subset of one or more working chambers and a second subset of one or more working chambers;

each working chamber in the first subset is arranged to be selectively fired or deactivated; and

each working chamber in the second subset is arranged to be fired during every engine cycle and is not capable of being deactivated during operation of the engine.

18. A method as recited in claim 1 wherein:

the engine includes a first subset of one or more working chambers that are each capable of generating the selected high and low torque output;

the engine further includes a second subset of one or more working chambers that are each not capable of generating the selected high and low torque output; and

the selection of the high or low torque output is from the fired working chambers in the first subset and not the second subset.

19. A method as recited in claim 1 wherein:

operating one of the fired working chambers to generate the low torque output at substantially a minimum brake specific fuel consumption condition.

20. A method as recited in claim 1 wherein:

the selection of high or low torque output on the fired working chambers is based at least in part on noise, vibration and harshness (NVH) considerations.

21. A method as recited in claim 1 further comprising:

using a higher air charge for the fired working chambers for which the high torque output was selected than for the fired working chambers for which the low torque output was selected.

22. A method as recited in claim 1 further comprising:

firing a selected working chamber at the high torque output based on the selection; and

firing a selected working chamber at the low torque output based on the selection wherein the low torque output firing is more fuel efficient than the high torque output firing.

23. A method as recited in claim 1 further comprising:

determining a plurality of candidate effective firing fractions that deliver the desired engine torque wherein each effective firing fraction is one or more values based on a cylinder torque level and a ratio of fires to firing opportunities;

comparing fuel efficiency of the candidate effective firing fractions;

based on the comparison, selecting one of the effective firing fractions; and

operating the engine based on the selected one of the candidate effective firing fractions.

24. A method as recited in claim 1 further comprising:

each fired working chamber includes a first intake valve and a first exhaust valve; and

actuating the first intake valve to deliver air to the fired working chamber wherein the first intake valve and the first exhaust valve of the fired working chamber are arranged such that whenever the first intake valve is actuated during a selected working cycle, the first exhaust valve is also actuated during the same selected working cycle.

25. A method as recited in claim 1 wherein all of the intake and exhaust valves are cam-actuated.

26. An engine controller for an engine including one or more working chambers, each working chamber including one or more cam-actuated intake valves, the engine controller comprising:

a firing fraction calculator arranged to determine a firing fraction suitable for delivering a desired engine torque;

a firing timing determination module arranged to determine a skip fire firing sequence based on the firing fraction wherein the skip fire firing sequence indicates whether, during a selected firing opportunity, a selected working chamber is deactivated or fired and further indicates, for each fire, whether the fire generates a low torque output or a high torque output; and

a firing control unit that is arranged to operate the one or more working chambers of the engine in a skip fire manner based on the firing sequence and wherein the firing control unit is further arranged to adjust air charge for each fired working chamber based on whether the firing sequence indicates a low torque output or a high torque output for the fired working chamber.

27. An engine controller as recited in claim 26 wherein the firing timing determination module is arranged to select the skip fire firing sequence from a library of predefined skip fire firing sequences.

28. An engine controller as recited in claim 26 wherein the firing timing determination module is arranged to generate the skip fire firing sequence using a sigma delta converter.

29. An engine controller as recited in claim 26 wherein the firing control unit is arranged to independently control intake valves for a selected working chamber in order to fire the selected working chamber at a high or low torque level based on the skip fire firing sequence.

30. An engine controller as recited in claim 26 wherein:

each of the working chambers of the engine includes a first intake valve and a second intake valve;

the firing control unit is further arranged to selectively open the first intake valve and not the second intake valve during a first selected working cycle; and

the firing control unit is further arranged to selectively open the first and second intake valves during a second selected working cycle such that timing of a closing and opening of the first and second intake valves during the second selected working cycle are different.

31. An engine controller as recited in claim 26 wherein:

the firing timing determination module is arranged to make firing decisions on a firing opportunity by firing opportunity basis, each firing decision indicating whether, during a selected firing opportunity, a selected working chamber is deactivated or fired and further indicates, for each fire, whether the fire generates a low torque output or a high torque output.

32. An engine system comprising:

an intake manifold;

a first set of one or more working chambers, each working chamber of the first set including a first intake valve and a second intake valve;

at least two intake passages that connect the intake manifold with one of the first set of working chambers wherein the at least two intake passages are arranged relative to the one of the working chambers such that a central axis of each of the intake passages substantially intersects with a central axis of the one of the working chambers.

33. An engine system as recited in claim 32, further comprising:

a first cam and a second cam that are arranged to independently actuate the first and second intake valves, respectively, wherein the engine system is arranged to independently actuate or deactivate the first and second intake valves on a working cycle by working cycle basis and wherein the independent actuation and deactivation of each of the first and second intake valves helps enable the working chamber to generate high or low torque output.

34. An engine system as recited in claim 33 further comprising:

a second set of one or more working chambers wherein each working chamber in the second set is not capable of generating a plurality of different levels of torque output.

35. An engine system as recited in claim 33 further comprising:

a second set of one or more working chambers wherein each working chamber in the second set is not capable of being deactivated during operation of the engine system.