Method for starting an engine in a parallel hybrid electric vehicle
First Claim
1. A system to start 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 disposed between the engine and the motor/generator 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 facilitate closing of the disconnect clutch to start engine rotation while facilitating operation of the motor/generator based on a desired motor/generator speed, the vehicle system controller being further configured to calculate a slip speed error, the slip speed error being the difference between an actual motor/generator speed and an actual engine speed.
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Accused Products
Abstract
The invention provides a strategy to start a parallel HEV powertrain engine while maintaining a smooth vehicle response to driver demand using the motor while simultaneously closing an engine disconnect clutch. In the preferred embodiment, the strategy starts an engine (based on, for example, driver demand), closes the disconnect clutch, commands a desired motor/generator speed, fuels the engine, calculates a desired engine torque and gradually reduces actual motor/generator torque while proportionally increasing actual engine torque until motor/generator torque is zero while maintaining vehicle velocity using, for example, a proportional plus integral controller. The prediction of a desired motor/generator speed can be: a trajectory comparison based on present and past vehicle velocity and acceleration or on vehicle accelerator position, or a determination of whether the vehicle is in speed control mode. The system can also add additional strategies such as a termination strategy if a vehicle brake is applied.
89 Citations
32 Claims
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1. A system to start 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 disposed between the engine and the motor/generator 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 facilitate closing of the disconnect clutch to start engine rotation while facilitating operation of the motor/generator based on a desired motor/generator speed, the vehicle system controller being further configured to calculate a slip speed error, the slip speed error being the difference between an actual motor/generator speed and an actual engine speed. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of starting an engine in a vehicle, the vehicle including a motor/generator, the method comprising:
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operating the motor/generator based on a desired motor/generator speed;
calculating a speed error, the speed error being the difference between an actual motor/generator speed and the desired motor generator speed;
connecting the motor/generator directly to the engine to start engine rotation, the connecting of the motor/generator to the engine including closing a disconnect clutch when the speed error is below a first calibratable tolerance, the disconnect clutch being disposed between the engine and the motor/generator for connecting the engine to, and disconnecting the engine from, the motor/generator;
fueling the engine, thereby facilitating engine start; and
sending a desired torque command to the engine. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of starting an engine in a vehicle, the vehicle including a motor/generator, the method comprising:
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entering an engine start mode;
operating the motor/generator based on a desired motor/generator speed;
connecting the motor/generator directly to the engine when a speed error is below a first calibratable tolerance, the speed error being the difference between an actual motor/generator speed and the desired motor/generator speed;
fueling the engine, thereby facilitating engine start, when a slip speed error is below a second calibratable tolerance for a first calibratable time, the slip speed error being the difference between the actual motor/generator speed and an actual engine speed; and
sending a desired torque command to the engine when the slip speed error is below the second calibratable tolerance for the first calibratable time. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. A controller for starting an engine in a vehicle, the vehicle including a motor/generator, the controller comprising:
an algorithm for commanding the connection of the motor/generator to the engine while facilitating operation of the motor/generator based on a desired motor/generator speed, and for commanding fueling of the engine when a slip speed error is below a second calibratable tolerance for a first calibratable time, the slip speed error being the difference between an actual motor/generator speed and an actual engine speed.
Specification