Engine control for smooth clutch engagement in a hybrid vehicle
A vehicle includes an engine, a traction motor, a clutch configured to mechanically couple the engine and traction motor, and a controller. The controller may be configured to, in response to an engine starting and achieving a target speed while the traction motor is generating torque to drive the vehicle, retard engine spark, based on an amount of engine acceleration required to achieve the target speed, to reduce engine torque, and in response to the engine torque falling below a threshold value, lock the clutch.
1. A vehicle control method comprising:
in response to an engine starting and achieving a target speed while an electric machine is generating torque to drive the vehicle, retarding engine spark to reduce engine torque; and
in response to the engine torque falling below a threshold value, locking a clutch configured to mechanically couple the engine and the electric machine.
2. The method of claim 1 , wherein an amount of the retarding is based on an engine torque required to achieve the target speed.
3. The method of claim 2 , wherein the engine torque required to achieve the target speed is based on a pre-defined time period.
4. The method of claim 3 , wherein a time period beginning with initiation of the retarding and ending with the engine torque falling below the threshold value is less than the pre-defined time period.
5. The method of claim 4 , wherein the pre-defined time period is equal to 300 ms and the time period is equal to 80 ms.
6. The method of claim 1 , further comprising, in response to the engine starting and achieving the target speed while the electric machine is generating torque to drive the vehicle, clipping engine air mass to reduce the engine torque.
7. A vehicle comprising:
an engine;
a traction motor;
a clutch configured to mechanically couple the engine and traction motor; and
a controller configured to,
in response to the engine starting and achieving a target speed while the traction motor is generating torque to drive the vehicle, retard engine spark, based on an amount of engine acceleration required to achieve the target speed, to reduce engine torque, and
in response to the engine torque falling below a threshold value, lock the clutch.
8. The vehicle of claim 7 , wherein the amount of engine acceleration required to achieve the target speed is based on a pre-defined time period.
9. The vehicle of claim 8 wherein a time period beginning with initiation of the reduction of engine torque and ending with the engine torque falling below the threshold value is less than the pre-defined time period.
10. The vehicle of claim 9 , wherein the pre-defined time period is equal to 300 ms and the time period beginning with initiation of the reduction of engine torque and ending with the engine torque falling below the threshold value is equal to 80 ms.
11. The vehicle of claim 7 , further comprising, in response to the engine starting and achieving the target speed while the traction motor is generating torque to drive the vehicle, clipping engine air mass to reduce the engine torque.
12. A controller for a vehicle comprising:
input channels configured to receive engine status indicators;
output channels configured to provide engine operating commands and clutch engagement commands; and
control logic configured to,
in response to engine status indicators indicative of an engine starting and achieving a target speed while an electric machine is generating torque to drive the vehicle, generate engine operating commands to retard engine spark to reduce engine torque, and
in response to engine status indicators indicative of the engine torque falling below a threshold value, generate clutch engagement commands to mechanically couple the engine and electric machine.
13. The controller of claim 12 , wherein an amount of the retarding is based on an engine torque required to achieve the target speed.
14. The controller of claim 13 , wherein the engine torque required to achieve the target speed is based on a pre-defined time period.
15. The controller of claim 14 , wherein a time period beginning with initiation of the retarding and ending with the engine torque falling below the threshold value is less than the pre-defined time period.
16. The controller of claim 15 , wherein the pre-defined time period is equal to 300 ms and the time period beginning with initiation of the retarding and ending with the engine torque falling below the threshold value is equal to 80 ms.
17. The controller of claim 13 , further comprising, in response to engine status indicators indicative of the engine starting and achieving the target speed while the electric machine is generating torque to drive the vehicle, clipping engine air mass to reduce the engine torque.