Skip fire engine control

• US 8,511,281 B2
• Filed: 07/09/2010
• Issued: 08/20/2013
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: Tula Technology, Incorporated
• Original Assignee: Tula Technology, Incorporated
• Inventors: Tripathi, Adya S., Silvestri, Chester J., Chandler, Christopher W., Hand, Chris, Switkes, Joshua P., Wilcutts, Mark
• Primary Examiner(s): Vo, Hieu T
• Application Number:
  US12/833,916
• Publication Number:
  US 20110030657A1
• Time in Patent Office: 1,138 Days
• Field of Search: 123/481, 123/198.DB, 123/198.F, 123/478, 123/480, 123/406.29, 701103-105, 701/102
• US Class Current: 123/481
• CPC Class Codes: F02D 17/02 Cutting-out cutting-out engines in multiple engine arrangements F02D25/04
• CPC Class Codes: F02D 41/0087 Selective cylinder activation, i.e. partial cylinder operation deceleration cut-off F02D41/123
• CPC Class Codes: F02D 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126

Abstract

A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. In the variable displacement mode, selected combustion events are skipped so that other working cycles can operate at better thermodynamic efficiency. More specifically, selected “skipped” working cycles are not fired while other “active” working cycles are fired. Typically, fuel is not delivered to the working chambers during skipped working cycles. In one aspect of the invention, a firing pattern is determined that is not fixed but the active working cycles are selected to favor the firing of working chambers that have recently been fired at least in part to reduce wall wetting losses. In another aspect of the invention, when an active working cycle follows a skipped working cycle in the same working chamber, the quanta of fuel injected for delivery to the working chamber is increased relative to the quanta of fuel that would be delivered to the working chamber when the active working cycle follows another active working cycle in the same working chamber in order to compensate for wall wetting losses that occur during skipped working cycles.

Claims

1. An engine controller for controlling the operation of an internal combustion engine having a plurality of working chambers, each working chamber being generally arranged to operate in a succession of working cycles, the engine controller comprising:

firing pattern determining logic arranged to determine a firing pattern that includes skipped working cycles and active working cycles, wherein at any given time, the firing pattern is not fixed but the active working cycles are selected to favor the firing of working chambers that have recently been fired at least in part to reduce wall wetting losses; and

fuel delivery logic arranged to direct the delivery of fuel to the working cycles in accordance with the determined firing pattern, wherein fuel is not affirmatively delivered to the working chambers during skipped working cycles and wherein fuel is affirmatively delivered to the working chambers during the active working cycles.

2. An engine controller for controlling the operation of an internal combustion engine having a plurality of working chambers, each working chamber being generally arranged to operate in a succession of working cycles, the engine controller comprising:

firing pattern determining logic arranged to determine a firing pattern that includes skipped working cycles and active working cycles, wherein at any given time, the firing pattern is not fixed; and

fuel delivery logic arranged to direct the delivery of fuel to the working cycles in accordance with the determined a firing pattern, wherein fuel is not affirmatively delivered to the working chambers during skipped working cycles and wherein fuel is affirmatively delivered to the working chambers during the active working cycles, wherein the fuel delivery logic is further arranged to increase the quanta of fuel injected during active working cycles that immediately follow a skipped working cycle in the same working chamber, relative to the quanta of fuel injected when the active working cycles immediately follow a previous active working cycle in the same working chamber at least in part to compensate for wall wetting losses that occur during skipped working cycles.

3. A method of controlling the operation of an internal combustion engine in a skip fire variable displacement mode, the engine including a plurality of working chambers, each working chamber being generally arranged to operate in a succession of working cycles, the method comprising:

determining a firing pattern that includes skipped working cycles and active working cycles, wherein at any given time, the firing pattern is not fixed but the active working cycles are selected to favor the firing of working chambers that have recently been fired at least in part to reduce wall wetting losses; and

delivering fuel to the working cycles in accordance with the determined firing pattern, wherein fuel is not affirmatively delivered to the working chambers during skipped working cycles and wherein fuel is affirmatively delivered to the working chambers during the active working cycles.

4. A method as recited in claim 3 wherein:

injectors are used to deliver fuel during the active working cycles; and

when an active working cycle follows a skipped working cycle in the same working chamber, the quanta of fuel injected for delivery to the working chamber is increased relative to the quanta of fuel that would be delivered to the working chamber when the active working cycle follows another active working cycle in the same working chamber in order to compensate for wall wetting losses that occur during skipped working cycles.

5. A method as recited in claim 3 wherein when at least half of the working cycles are skipped working cycles, more than half of the active working cycles occur in working chambers in which the immediately preceding working cycle was an active working cycle.

6. A method as recited in claim 5 wherein at least 70% of the active working cycles occur in working chambers in which the immediately preceding working cycle was an active working cycle.

7. A method of controlling the operation of an internal combustion engine in a skip fire variable displacement mode, the engine including a plurality of working chambers, each working chamber being generally arranged to operate in a succession of working cycles, the method comprising:

determining a firing pattern that includes skipped working cycles and active working cycles, wherein at any given time, the firing pattern is not fixed; and

delivering fuel to and firing the working cycles in accordance with the determined firing pattern, wherein skipped working cycles are not fired and fuel is not affirmatively delivered to the working chambers during skipped working cycles and wherein active working cycles are fired and fuel is affirmatively delivered to the working chambers during the active working cycles; and

wherein injectors are used to deliver fuel during the active working cycles; and

wherein when an active working cycle follows a skipped working cycle in the same working chamber, the quanta of fuel injected for delivery to the working chamber is increased relative to the quanta of fuel that would be delivered to the working chamber when the active working cycle follows another active working cycle in the same working chamber in order to compensate for wall wetting losses that occur during skipped working cycles.