Hybrid Electric Vehicle Powertrain with Engine Start and Transmission Shift Arbitration
First Claim
1. A method for controlling a hybrid electric vehicle powertrain having an engine, at least one motor-generator, a multiple-ratio transmission defining parallel power flow paths to vehicle traction wheels and a controller for effecting a transition from motor-generator drive operation to engine drive operation, the method comprising the steps of:
- determining whether the powertrain is operating in motor-generator drive operation with the engine off;
determining whether a desired power is less than a calibrated engine-on power threshold value;
calculating a predicted time to start the engine in advance of a transmission ratio shift;
calculating a predicted time to shift the transmission from one ratio to another ratio;
comparing the predicted time to shift the transmission to the predicted time to start the engine; and
starting the engine if the predicted time to shift the transmission is greater than the predicted time to start the engine, whereby a smooth transition from motor-generator drive operation to engine drive operation is achieved.
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Accused Products
Abstract
A control method and control system for a hybrid electric vehicle powertrain with a multiple-ratio transmission is disclosed in which engine start events are separated in time from transmission ratio shift events to effect a smooth transition from an electric drive state with the engine off to a drive state in which the engine delivers driving power.
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Citations
14 Claims
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1. A method for controlling a hybrid electric vehicle powertrain having an engine, at least one motor-generator, a multiple-ratio transmission defining parallel power flow paths to vehicle traction wheels and a controller for effecting a transition from motor-generator drive operation to engine drive operation, the method comprising the steps of:
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determining whether the powertrain is operating in motor-generator drive operation with the engine off; determining whether a desired power is less than a calibrated engine-on power threshold value; calculating a predicted time to start the engine in advance of a transmission ratio shift; calculating a predicted time to shift the transmission from one ratio to another ratio; comparing the predicted time to shift the transmission to the predicted time to start the engine; and starting the engine if the predicted time to shift the transmission is greater than the predicted time to start the engine, whereby a smooth transition from motor-generator drive operation to engine drive operation is achieved. - View Dependent Claims (4, 5)
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2. A method for controlling a hybrid electric vehicle powertrain having an engine, at least one motor-generator, a multiple-ratio transmission defining parallel power flow paths to vehicle traction wheels and a controller for effecting a transition from motor-generator drive operation to engine drive operation, the method comprising:
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determining whether the powertrain is operating with the engine off; calculating a desired rate of increase in desired transmission input power; determining whether the desired transmission input power is less than a pre-calibrated engine-on power threshold; determining a desired transmission input power; calculating a predicted time to start the engine in advance of a transmission ratio shift as a function of at least the desired rate of increase in transmission input power; measuring vehicle speed; calculating a predicted time to shift the transmission from one ratio to another ratio as a function of at least vehicle acceleration; comparing the predicted time to shift the transmission to the predicted time to start the engine; and starting the engine if the predicted time to shift the transmission is greater than the predicted time to start the engine whereby an engine start is separated in time from a transmission shift to improve smoothness in a transition from motor-generator drive operation to engine drive operation. - View Dependent Claims (3, 6, 7, 8, 9, 10)
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11. A method for controlling a hybrid electric vehicle powertrain having an engine, at least one motor-generator, a multiple-ratio transmission defining parallel power flow paths to vehicle traction wheels and a controller for effecting a transition from motor-generator drive operation to engine drive operation, the method comprising:
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determining whether the powertrain is operating with the engine off; calculating a desired rate of increase in desired transmission input power; determining a desired transmission input power; determining whether the desired transmission input power is less than a pre-calibrated engine-on power threshold; calculating a predicted time to start the engine in advance of a transmission ratio shift as a function of at least the desired rate of increase in transmission input power; measuring vehicle speed; calculating a predicted time to shift the transmission from one ratio to another ratio as a function of at least vehicle acceleration; comparing the predicted time to shift the transmission to the predicted time to start the engine; starting the engine if the predicted time to shift the transmission is greater than the predicted time to start the engine whereby an engine start is separated in time from a transmission shift to improve smoothness in a transition from motor-generator drive operation to engine drive operation; and establishing an engine start priority over a transmission shift event if the calculated time to start the engine is shorter than a calibrated time to start the engine regardless of the calculated predicted time to shift the transmission. - View Dependent Claims (12)
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13. A control system for controlling a hybrid electric vehicle powertrain having an engine, at least one motor-generator, a battery, a multiple-ratio transmission defining parallel power flow paths to vehicle traction wheels, a powertrain controller network including a vehicle system controller for establishing and disestablishing each of a plurality of powertrain operating states including an engine-only operating state, an operating state in which both the engine and the motor-generator are active and a motor-generator drive state in which the engine is inactive;
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a transmission controller in communication with the vehicle system controller in the powertrain controller network for effecting ratio shifts in the transmission in response to driver and powertrain operating input variables; and an engine controller in communication with the vehicle system controller in the powertrain controller network for establishing an engine-on state and an engine-off state in response to commands from the vehicle system controller; the powertrain controller network being configured to predict a time to start the engine following operation of the powertrain in the motor-generator drive state with the engine off and to predict a time to shift the transmission ratio; the powertrain controller network being configured further to start the engine when the predicted time to shift is greater than the predicted time to start the engine whereby an engine start event and a transmission ratio shift event are separated in time to effect a smooth transition from a motor-generator drive state to an engine drive state. - View Dependent Claims (14)
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Specification