Method for stopping an engine in a parallel hybrid electric vehicle
First Claim
1. A system to stop an engine in a vehicle, the system comprising:
- a motor/generator;
a power transfer unit;
a vehicle powertrain connecting the engine, the motor/generator, and the power transfer unit;
a disconnect clutch for connecting the engine to, and disconnecting the engine from, the motor/generator; and
a vehicle system controller, the vehicle system controller being configured to determine a desired motor/generator speed, and to determine when to stop the engine based in part on the desired motor/generator speed.
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Accused Products
Abstract
The invention provides a strategy to stop a parallel HEV powertrain engine while maintaining smooth vehicle response to driver demand using the motor while simultaneously opening an engine disconnect clutch. In the preferred embodiment, the strategy stops an engine (based on, for example, driver demand), disconnects the disconnect clutch to the powertrain, halts fuel to the engine, and predicts a desired motor/generator speed. The prediction of desired motor/generator speed can be: a trajectory comparison based on present and past vehicle velocity and deceleration or on a vehicle accelerator position, or a determination of whether the vehicle is in speed following control mode. The system can also add additional strategies such as accelerate the strategy if a vehicle brake is applied. The gradual takeover by the motor occurs by proportionally decreasing actual engine torque until engine torque is zero while maintaining vehicle velocity using for example a proportional plus integral controller.
50 Citations
33 Claims
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1. A system to stop an engine in a vehicle, the system comprising:
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a motor/generator;
a power transfer unit;
a vehicle powertrain connecting the engine, the motor/generator, and the power transfer unit;
a disconnect clutch for connecting the engine to, and disconnecting the engine from, the motor/generator; and
a vehicle system controller, the vehicle system controller being configured to determine a desired motor/generator speed, and to determine when to stop the engine based in part on the desired motor/generator speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of stopping an engine in a vehicle, the vehicle including a motor/generator, the method comprising:
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determining a desired motor/generator speed;
operating the motor/generator based on the desired motor/generator speed;
determining an actual motor/generator speed;
comparing the desired motor/generator speed to the actual motor/generator speed to determine a speed error;
comparing the speed error to a calibratable tolerance;
halting fueling of the engine when the speed error is below the calibratable tolerance; and
opening a clutch when the speed error is below the calibratable tolerance, the clutch being configured to at least connect the engine to, and disconnect the engine from, the motor/generator. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of stopping an engine in a vehicle, the vehicle including a vehicle system controller, a motor, and a clutch connecting the engine to the motor, the method comprising:
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entering an engine stop mode based on a command from the vehicle system controller;
determining a desired motor/generator speed;
sending a speed command to the motor/generator based on the desired motor speed;
determining an actual motor/generator speed;
comparing the desired motor/generator speed to the actual motor/generator speed to determine a speed error;
comparing the speed error to a calibratable tolerance;
halting fueling of the engine when the speed error is below the calibratable tolerance;
opening the clutch when the speed error is below the calibratable tolerance;
determining whether the clutch is fully open; and
exiting the engine stop mode when it is determined that the clutch is fully open. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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Specification