Coordination of vehicle actuators during firing fraction transitions
First Claim
1. A method of managing firing fraction transitions in a vehicle having a powertrain that includes an engine and a drivetrain that includes an adjustable slip drivetrain component, the method comprising:
- while the engine is operating at a first firing fraction and the adjustable slip drivetrain component is operating at a first drivetrain slip, determining a requested second firing fraction that is different than the first firing fraction, the second firing fraction having an associated second drivetrain slip and an associated second drivetrain slip transition threshold that is higher than the first drivetrain slip;
initiating a transition from the first drivetrain slip towards the second drivetrain slip;
transitioning to a target firing fraction that is different than the first and second firing fractions, the target firing fraction (i) being selected from a set of available firing fractions capable of delivering a requested engine output, and (ii) having an associated target drivetrain slip transition threshold that is less the second drivetrain slip transition threshold; and
after transitioning to the target firing fraction, transitioning to the second firing fraction, andwherein each firing fraction transition is constrained to only occur when an actual driveline slip is at least as high as the associated drivetrain slip transition threshold.
1 Assignment
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Accused Products
Abstract
A variety of methods and arrangements are described for controlling transitions between firing fractions during skip fire or dynamic firing level modulation operation of an engine. In general, actuator first transition strategies are described in which an actuator position (e.g., cam phase, TCC slip, etc.) is changed to, or close to a target position before a corresponding firing fraction change is implemented. When the actuator change associated with a desired firing fraction change is relatively large, the firing fraction change is divided into a series of two or more firing fraction change steps. A number of intermediate target selection schemes are described as well.
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Citations
33 Claims
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1. A method of managing firing fraction transitions in a vehicle having a powertrain that includes an engine and a drivetrain that includes an adjustable slip drivetrain component, the method comprising:
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while the engine is operating at a first firing fraction and the adjustable slip drivetrain component is operating at a first drivetrain slip, determining a requested second firing fraction that is different than the first firing fraction, the second firing fraction having an associated second drivetrain slip and an associated second drivetrain slip transition threshold that is higher than the first drivetrain slip; initiating a transition from the first drivetrain slip towards the second drivetrain slip; transitioning to a target firing fraction that is different than the first and second firing fractions, the target firing fraction (i) being selected from a set of available firing fractions capable of delivering a requested engine output, and (ii) having an associated target drivetrain slip transition threshold that is less the second drivetrain slip transition threshold; and after transitioning to the target firing fraction, transitioning to the second firing fraction, and wherein each firing fraction transition is constrained to only occur when an actual driveline slip is at least as high as the associated drivetrain slip transition threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of controlling an engine in a vehicle having a powertrain that includes the engine and a drivetrain that includes an adjustable slip drivetrain component, the method comprising:
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while the engine is operating at a first firing fraction having an associated first drivetrain component slip, determining a desired second firing fraction and an associated second drivetrain component slip, the second drivetrain component slip being different than the first drivetrain component slip; initiating a transition from the first drivetrain component slip to the second drivetrain component slip; after an actual drivetrain component slip is at or within a predetermined range of the second drivetrain component slip, transitioning to the second firing fraction, wherein the transition to the second firing fraction is initiated only after the actual drivetrain component slip is at or within the predetermined range of the second drivetrain component slip; and directing operation of the engine during the transitions to deliver a requested output, whereby an actual commanded firing fraction gradually changes during the transition from the first firing fraction to the second firing fraction. - View Dependent Claims (14, 15)
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16. A method of controlling an engine in a vehicle having a powertrain that includes the engine and a drivetrain that includes an adjustable slip drivetrain component, the method comprising:
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(a) while the engine is operating at a first firing fraction and the adjustable slip drivetrain component is operating at a first drivetrain slip, determining a requested second firing fraction that is different than the first firing fraction, the second firing fraction having an associated second drivetrain slip, the second drivetrain slip being higher than the first drivetrain slip; (b) initiating a transition from the first drivetrain slip to the second drivetrain slip; (c) identifying a target firing fraction that is different than the first and second firing fractions from a set of available firing fractions capable of delivering a requested engine output, the target firing fraction having an associated target drivetrain slip that is less the second drivetrain slip; (d) transitioning to the target firing fraction, wherein the transition to the target firing fraction is constrained to only occur when an actual driveline slip is at least as high as a target driveline slip threshold associated with the target firing fraction; and (e) after transitioning to the target firing fraction, transitioning to the second firing fraction, wherein the transition to the second firing fraction is constrained to only occur when the actual driveline slip is at least as high as a second driveline slip threshold associated with the second firing fraction; and (f) directing operation of the engine during the transitions to deliver the requested engine output. - View Dependent Claims (17, 18, 19, 20)
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21. A method of controlling an engine in a vehicle having a powertrain that includes the engine and a drivetrain that includes a torque converter clutch (TCC) the method comprising:
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(a) while the engine is operating at a first firing fraction and the torque converter is operating at a first slip, determining a requested firing fraction that is lower than the first firing fraction, the requested firing fraction being a second firing fraction having an associated second torque converter slip, the second torque converter slip being higher than the first torque converter slip; (b) initiating a transition from the first torque converter slip to the second torque converter slip; (c) selecting an intermediate firing fraction that is between the first and second firing fractions, the intermediate firing fraction having an associated torque converter slip; (d) identifying the selected intermediate firing fraction as a target firing fraction; (e) transitioning to the target firing fraction, wherein the transition to the target firing fraction is constrained to only occur when an actual torque converter slip is at least as high as, or within a predetermined range of the torque converter slip associated with the target firing fraction; (f) when the target firing fraction is not the second firing fraction, selecting a next firing fraction having an associated next torque converter slip and setting the target firing fraction to be the next firing fraction; (g) iteratively repeating (e) and (f) until the requested firing fraction is reached; and (h) directing operation of the engine during the transitions to deliver a requested output. - View Dependent Claims (22, 23, 24, 25, 26)
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27. A powertrain controller arranged to direct skip fire operation of an engine and to direct a slip setting of a drivetrain component, the powertrain controller being configured to:
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direct operation of the engine at a first firing fraction and direct operation of the drivetrain component at a first slip; while the engine is operating at the first firing fraction and the drivetrain component is operating at the first drivetrain slip, determine a requested second firing fraction that is different than the first firing fraction, the second firing fraction having an associated second drivetrain slip and an associated second drivetrain slip transition threshold that is higher than the first drivetrain slip; initiate a transition from the first drivetrain slip towards the second drivetrain slip; direct transition to a target firing fraction that is different than the first and second firing fractions, the target firing fraction (i) being selected from a set of available firing fractions capable of delivering a requested engine output, and (ii) having an associated target drivetrain slip transition threshold that is less than the second drivetrain slip transition threshold; and after directing transition to the target firing fraction, direct transition to the second firing fraction, wherein each firing fraction transition is only directed when an actual driveline slip is at least as high as the associated drivetrain slip transition threshold. - View Dependent Claims (28, 29, 30, 31)
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32. A powertrain controller arranged to direct skip fire operation of an engine and to direct a slip setting of a drivetrain component, the powertrain controller being configured to:
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direct operation of the engine at a first firing fraction and operation of the drivetrain component at a first drivetrain component slip; while the engine is operating at the first firing fraction and the drivetrain component is operating at the first drivetrain component slip, determine a desired second firing fraction and an associated second drivetrain component slip, the second drivetrain component slip being different than the first drivetrain component slip; initiate a transition from the first drivetrain component slip to the second drivetrain component slip; after an actual drivetrain component slip is at or within a predetermine range of the second drivetrain component slip, direct a transition to the second firing fraction, wherein the transition to the second firing fraction is initiated only after the actual drivetrain component slip is at or within the predetermined range of the second drivetrain component slip; and direct operation of the engine during the drivetrain component slip and firing fraction transitions to deliver a requested output. - View Dependent Claims (33)
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Specification