Vehicle and method for controlling engine start in a vehicle
First Claim
1. A method for starting an engine in a hybrid vehicle being driven by an electric machine, comprising:
- operating a starter motor;
reducing a launch clutch pressure command to cause slip;
raising a pressure command to a first clutch transferring torque to the engine when launch clutch slip has reached a predetermined level;
turning off the starter motor;
fueling the engine; and
fully engaging the launch clutch after desired engine torque is achieved.
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.
71 Citations
20 Claims
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1. A method for starting an engine in a hybrid vehicle being driven by an electric machine, comprising:
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operating a starter motor; reducing a launch clutch pressure command to cause slip; raising a pressure command to a first clutch transferring torque to the engine when launch clutch slip has reached a predetermined level; turning off the starter motor; fueling the engine; and fully engaging the launch clutch after desired engine torque is achieved. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for starting an engine in a hybrid 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; initiating operation of a starter motor substantially simultaneously with raising the pressure of the first clutch 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 (10, 11, 12, 13, 14, 15, 16, 17)
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18. A hybrid 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 and 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, 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 start the engine is reduced, raise the pressure of the first clutch to transfer torque from the electric machine to the engine while the starter motor is still operating; turn off the starter motor, fuel the engine, and fully engage the first clutch. - View Dependent Claims (19, 20)
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Specification