Engine torque smoothing
First Claim
1. A method of control of a hybrid vehicle having an internal combustion engine and an auxiliary power source/sink, the method comprising:
- determining a torque profile for the internal combustion engine by;
determining a normalized torque profile for each stroke of a cylinder in the engine, wherein the normalized torque profile is based on intake manifold pressure;
scaling the normalized torque profile to determine the cylinder torque; and
summing the cylinder torques for all cylinders in the engine to obtain an overall engine torque profile;
determining whether the torque profile provides acceptable NVH;
when the torque profile is determined to provide acceptable NVH, operating the hybrid vehicle solely on the output of the internal combustion engine; and
when the torque profile is determined to provide unacceptable NVH, operating the hybrid vehicle on both the internal combustion engine and the auxiliary power source/sink, wherein the auxiliary power source/sink provides a smoothing torque to reduce NVH to an acceptable level.
1 Assignment
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Accused Products
Abstract
Methods, devices, estimators, controllers and algorithms are described for estimating the torque profile of an engine and/or for controlling torque applied to a powertrain by one or more devices other than the engine itself to manage the net torque applied by the engine and other device(s) in manners that reduce undesirable NVH. The described approaches are particularly well suitable for use in hybrid vehicles in which the engine is operated in a skip fire or other dynamic firing level modulation manner—however they may be used in a variety of other circumstances as well. In some embodiments, the hybrid vehicle includes a motor/generator that applies the smoothing torque.
139 Citations
32 Claims
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1. A method of control of a hybrid vehicle having an internal combustion engine and an auxiliary power source/sink, the method comprising:
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determining a torque profile for the internal combustion engine by; determining a normalized torque profile for each stroke of a cylinder in the engine, wherein the normalized torque profile is based on intake manifold pressure; scaling the normalized torque profile to determine the cylinder torque; and summing the cylinder torques for all cylinders in the engine to obtain an overall engine torque profile; determining whether the torque profile provides acceptable NVH; when the torque profile is determined to provide acceptable NVH, operating the hybrid vehicle solely on the output of the internal combustion engine; and when the torque profile is determined to provide unacceptable NVH, operating the hybrid vehicle on both the internal combustion engine and the auxiliary power source/sink, wherein the auxiliary power source/sink provides a smoothing torque to reduce NVH to an acceptable level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method comprising:
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operating an engine, the engine being part of a powertrain; estimating an engine generated torque or angular acceleration profile during operation of the engine; based on the estimated torque or angular acceleration profile, identifying periods where an instantaneous torque or an instantaneous acceleration produced by the engine is expected to exceed a designated threshold, the designated threshold being an instantaneous torque threshold or an instantaneous acceleration threshold; and applying a counteracting torque to a component of a powertrain from an energy source or sink during the identified periods such that an expected overall powertrain torque does not exceed the designated threshold, wherein the designated threshold varies as a function of engine speed and transmission gear. - View Dependent Claims (9, 10, 11, 12)
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13. A method of controlling an output of a powertrain that includes an engine configured to apply torque to the powertrain, the method comprising:
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determining an expected engine torque profile associated with a sequence of one or more engine firing opportunities; determining whether the expected engine torque profile predicts the occurrence of one or more torque spikes that exceed a designated torque spike threshold; and for each predicted torque spike that exceeds the designated torque spike threshold, causing an opposing torque impulse to be applied to the powertrain, the opposing torque impulse being arranged to cause a net torque applied to the powertrain to not exceed the designated torque spike threshold, wherein the designated torque spike threshold varies as a function of engine speed and transmission gear. - View Dependent Claims (14, 15, 16)
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17. A method of determining an operational firing fraction for delivering a desired engine output during operation of an engine, the method comprising:
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(a) determining an estimated torque profile associated with operating the engine at a candidate firing fraction under current engine operating conditions to deliver the desired engine output; (b) determining whether a smoothing torque would be required to meet NVH criteria during operation of the engine at the candidate firing fraction under the current engine operating conditions; (c) determining a fuel efficiency associated with the candidate firing fraction; (d) repeating steps (a)-(c) for each of a plurality of candidate firing fractions; and (e) selecting one of the candidate firing fractions as the operational firing fraction based at least in part of the determined fuel efficiency of the candidate firing fractions, wherein the fuel efficiency implications of applying the smoothing torque are considered in the determination of the fuel efficiency of each candidate firing fraction that requires a smoothing torque. - View Dependent Claims (18, 19, 21, 22, 23, 24, 25)
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20. A method as recited in 17 wherein each torque profile is based at least in part on intake manifold pressure, engine speed, camshaft phase and spark timing.
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26. A method of control of a hybrid vehicle having an internal combustion engine and an auxiliary power source/sink, the method comprising:
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operating the internal combustion engine in a dynamic skip fire mode, wherein for a given reduced effective displacement that is less than full displacement of the internal combustion engine, a firing decision to either fire or skip firing a cylinder of the internal combustion engine is dynamically made on a firing opportunity-by-firing opportunity basis; determining a torque profile for the internal combustion engine; determining whether the torque profile provides acceptable NVH; when the torque profile is determined to provide acceptable NVH, operating the hybrid vehicle solely on the output of the internal combustion engine; and when the torque profile is determined to provide unacceptable NVH while operating in the dynamic skip fire mode, operating the hybrid vehicle on both the internal combustion engine and the auxiliary power source/sink, wherein the auxiliary power source/sink provides a smoothing torque to reduce NVH to an acceptable level. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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Specification