Vehicle And Method For Controlling Engine Start In A Vehicle
First Claim
1. A method for starting an engine in a vehicle, comprising:
- requesting an engine start;
operating an electric machine;
engaging a first clutch disposed between the engine and the electric machine to bring a pressure of the first clutch to a first level providing for subsequent rapid engagement of the first clutch;
initiating operation of a starter motor substantially simultaneously with the engagement of the first clutch, such that torque is transferred from the starter motor to the engine and required torque transfer from the electric machine to the engine is reduced;
reducing the pressure of the first clutch to a second level while the starter motor is operating;
raising the pressure of the first clutch to a third level when the slip in the launch clutch has reached a predetermined level such that torque is transferred from the electric machine to the engine while the starter motor is still operating;
turning off the starter motor when a speed of the engine is a predetermined speed above a speed of the starter motor; and
fully engaging the first clutch.
1 Assignment
0 Petitions
Accused Products
Abstract
A vehicle includes a motor/generator, a starter motor, a disconnect clutch disposed between the engine and the motor/generator, and at least one clutch disposed between the motor/generator and the vehicle drive wheels. When an engine start is requested, various parameters are controlled to ensure a smooth engine start wherein driveline torque disturbances are minimized. The starter motor is used to crank the engine at the lowest engine speeds when the engine-required torque is the highest. This reduces the amount of torque necessary to be supplied from the motor/generator, and further helps to reduce torque disturbances in the driveline. If the motor/generator is producing torque to propel the vehicle at the time the engine start is requested, a launch clutch or one or more transmission clutches can be controlled to provide slip between the motor/generator and the vehicle drive wheels to further reduce torque disturbances in the driveline.
81 Citations
18 Claims
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1. A method for starting an engine in a vehicle, comprising:
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requesting an engine start; operating an electric machine; engaging a first clutch disposed between the engine and the electric machine to bring a pressure of the first clutch to a first level providing for subsequent rapid engagement of the first clutch; initiating operation of a starter motor substantially simultaneously with the engagement of the first clutch, such that torque is transferred from the starter motor to the engine and required torque transfer from the electric machine to the engine is reduced; reducing the pressure of the first clutch to a second level while the starter motor is operating; raising the pressure of the first clutch to a third level when the slip in the launch clutch has reached a predetermined level such that torque is transferred from the electric machine to the engine while the starter motor is still operating; turning off the starter motor when a speed of the engine is a predetermined speed above a speed of the starter motor; and fully engaging the first clutch. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for starting an engine in a vehicle, comprising:
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requesting an engine start when a first clutch disposed between the engine and an electric machine is at least substantially disengaged; operating the electric machine; engaging the first clutch from the at least substantially disengaged state to bring a pressure of the first clutch to a first level providing for subsequent rapid engagement of the first clutch; initiating operation of a starter motor substantially simultaneously with the engagement of the first clutch, such that torque is transferred from the starter motor to the engine and required torque transfer from the electric machine to the engine is reduced; raising the pressure of the first clutch to a third level such that torque is transferred from the electric machine to the engine while the starter motor is still operating; turning off the starter motor; and fully engaging the first clutch. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15)
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16. A vehicle including vehicle drive wheels, the vehicle comprising:
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an engine; a starter motor for rotating the engine to facilitate an engine start; an electric machine operable to propel the vehicle and to rotate the engine; a first clutch disposed between the engine and the electric machine for selectively connecting the engine to the electric machine; and a control system including at least one controller, the control system being configured to; request an engine start when the first clutch is at least substantially disengaged, operate the electric machine, engage the first clutch from the at least substantially disengaged state to bring a pressure of the first clutch to a first level providing for subsequent rapid engagement of the first clutch, initiate operation of the starter motor substantially simultaneously with the engagement of the first clutch, such that torque is transferred from the starter motor to the engine and required torque transfer from the electric machine to the engine is reduced, raise the pressure of the first clutch to a third level such that torque is transferred from the electric machine to the engine while the starter motor is still operating; turn off the starter motor, fuel the engine, thereby facilitating torque production by the engine, and fully engage the first clutch. - View Dependent Claims (17, 18)
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Specification