Torque converter clutch lockup during skip-fire operation
First Claim
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1. A method of operating a vehicle having an internal combustion engine and a powertrain, wherein the powertrain includes an engine-decoupling friction interface and has one or more resonant frequencies of concern, the method comprising:
- operating the engine in a skip-fire manner to supply motive power to move the vehicle;
transferring the engine motive power through the friction interface;
while the engine is operating in the skip-fine manner, automatically determining whether current skip-fire operating conditions are suitable for locking-up the friction interface, wherein the friction interface lock-up determination is based at least in part on current engine speed and current skip-fire firing fraction and is arranged to ensure that a current combustion frequency does not incite any of the one or more resonant frequencies of concern; and
locking-up the friction interface during operation in the skip-fire manner when it is determined that current skip fire operating conditions are suitable for locking-up the friction interface.
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Abstract
A variety of methods and arrangements for determining conditions when an engine-decoupling friction interface may be locked-up during skip-fire operation of an internal combustion engine are described. In some embodiments, the engine-decoupling friction interface is the lockup clutch of a torque converter situated in a powertrain that transmits motive power from the engine to a wheel. Rotation of the wheel causes vehicle motion.
47 Citations
18 Claims
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1. A method of operating a vehicle having an internal combustion engine and a powertrain, wherein the powertrain includes an engine-decoupling friction interface and has one or more resonant frequencies of concern, the method comprising:
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operating the engine in a skip-fire manner to supply motive power to move the vehicle; transferring the engine motive power through the friction interface; while the engine is operating in the skip-fine manner, automatically determining whether current skip-fire operating conditions are suitable for locking-up the friction interface, wherein the friction interface lock-up determination is based at least in part on current engine speed and current skip-fire firing fraction and is arranged to ensure that a current combustion frequency does not incite any of the one or more resonant frequencies of concern; and locking-up the friction interface during operation in the skip-fire manner when it is determined that current skip fire operating conditions are suitable for locking-up the friction interface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method of operating a vehicle having an internal combustion engine and a powertrain, wherein the powertrain includes an engine-decoupling friction interface, the method comprising:
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determining a set of available skip fire firing fractions capable of delivering a currently requested engine output each available skip fire firing fraction having an associated friction interface slip at current operating conditions; selecting an operational skip fire firing fraction from a set of available skip fire firing fractions that are capable of delivering the desired engine output, wherein the selection of the operational skip fire firing fraction is based in part on the friction interface slip associated with the selected operational skip fire firing fraction indicating that the friction interface may be locked-up during operation at the current operating conditions; operating the engine at the selected operational skip fire firing fraction to supply motive power to move the vehicle; transferring the engine motive power through the friction interface; locking-up the friction interface so that losses in the engine-decoupling friction interface are minimized so as to provide overall optimum vehicle fuel efficiency.
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17. A method of operating a vehicle having an internal combustion engine and a powertrain, wherein the powertrain has a specified tuned absorber frequency and includes an engine-decoupling friction interface, the method comprising:
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determining a set of available skip fire firing fractions capable of delivering a currently requested engine output; selecting an operational firing fraction from the set of available skip fire firing fractions, wherein the selected operational firing fraction has a characteristic frequency close to the specified tuned absorber frequency at a current engine speed; and locking-up the friction interface while operating at the selected operational firing fraction. - View Dependent Claims (18)
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Specification