Power-on downshift control for a hybrid electric vehicle powertrain
First Claim
1. A method for controlling power distribution in a hybrid electric vehicle powertrain, the powertrain comprising an engine, a multiple-ratio transmission having a power delivery member drivably connected to the engine for developing a mechanical driving power flow path to vehicle traction wheels, a first electric machine coupled to the engine and a second electric machine in an electrical power flow path to the vehicle traction wheels, the transmission having selectively engageable friction elements for establishing at least two forward drive transmission ratios, one friction element being released as a second friction element is engaged to effect a power-on downshift, the method comprising:
- increasing torque output of the second electric machine in a first operating mode at the beginning of the power-on downshift following a shift request;
maintaining torque delivered through the mechanical driving power flow path at approximately its pre-shift level as the first friction element is slipping and the second friction element is engaging in a second operating mode;
maintaining torque output of the second electric machine during the second operating mode;
decreasing the torque output of the second electric machine in a third operating mode at the end of the power-on downshift; and
increasing torque delivered through the mechanical power flow path to fully engage the second friction element in the third operating mode as the torque output of the second electric machine returns to approximately its pre-shift level whereby a fast response to a request for an increase in traction wheel torque is achieved.
2 Assignments
0 Petitions
Accused Products
Abstract
A method for controlling a hybrid electric vehicle powertrain having an engine, a multiple-ratio transmission, a first electric machine and a second electric machine. On a power-on transmission downshift, electric wheel torque is used to compensate for a slow response of an engine to a request for increased traction wheel torque.
-
Citations
12 Claims
-
1. A method for controlling power distribution in a hybrid electric vehicle powertrain, the powertrain comprising an engine, a multiple-ratio transmission having a power delivery member drivably connected to the engine for developing a mechanical driving power flow path to vehicle traction wheels, a first electric machine coupled to the engine and a second electric machine in an electrical power flow path to the vehicle traction wheels, the transmission having selectively engageable friction elements for establishing at least two forward drive transmission ratios, one friction element being released as a second friction element is engaged to effect a power-on downshift, the method comprising:
-
increasing torque output of the second electric machine in a first operating mode at the beginning of the power-on downshift following a shift request; maintaining torque delivered through the mechanical driving power flow path at approximately its pre-shift level as the first friction element is slipping and the second friction element is engaging in a second operating mode; maintaining torque output of the second electric machine during the second operating mode; decreasing the torque output of the second electric machine in a third operating mode at the end of the power-on downshift; and increasing torque delivered through the mechanical power flow path to fully engage the second friction element in the third operating mode as the torque output of the second electric machine returns to approximately its pre-shift level whereby a fast response to a request for an increase in traction wheel torque is achieved. - View Dependent Claims (2, 3, 4, 5, 6)
-
-
7. A method for controlling power distribution in a hybrid electric vehicle powertrain, the powertrain comprising an engine, a multiple-ratio transmission having a power delivery member drivably connected to the engine for developing a mechanical driving power flow path to vehicle traction wheels, a first electric machine coupled to the engine and a second electric machine in an electrical power flow path to the vehicle traction wheels, the transmission having selectively engageable friction elements for establishing at least two forward drive transmission ratios, one friction element being released as a second friction element is engaged to effect a power-on downshift, the method comprising:
-
maintaining torque output of the second electric machine and maintaining torque delivered through the mechanical driving power flow path at appropriately their respective pre-shift levels in a first operating mode of the power-on downshift following a shift request; decreasing torque delivered through the mechanical driving power flow path to a value less than its pre-shift level to effect slipping of the first friction element during a second operating mode of the power-on downshift; increasing torque output of the second electric machine during the second operating mode to a level greater than its pre-shift level during the second operating mode; decreasing the torque output of the second electric machine during a third operating mode of the power-on downshift to a level approximately the same as the its pre-shift level; and increasing torque delivered through the mechanical power flow path during the third operating mode as the second friction element becomes fully engaged whereby the duration of the power-on downshift is shortened. - View Dependent Claims (8, 9, 10)
-
-
11. A method for controlling power distribution in a hybrid electric vehicle powertrain, the powertrain comprising an engine, a multiple-ratio transmission having a power delivery member drivably connected to the engine for developing a mechanical driving power flow path to vehicle traction wheels, a first electric machine coupled to the engine and a second electric machine in an electrical power flow path to the vehicle traction wheels, the transmission having selectively engageable friction elements for establishing at least two forward drive transmission ratios, one friction element being released as a second friction element is engaged to effect a power-on downshift, the method comprising:
-
increasing torque output of the second electric machine to a first level in a first operating mode at the beginning of the power-on downshift following a shift request; increasing torque output of the second electric machine to a higher second level in a second operating mode; maintaining torque delivered through the mechanical driving power flow path at approximately its pre-shift level in the first operating mode; decreasing torque delivered through the mechanical power flow path during the second operating mode to a level approximately equal to a difference between the first and second levels of torque for the second electric machine; decreasing the torque output of the second electric machine during a third operating mode at the end of the power-on downshift; and increasing torque delivered through the mechanical power flow path during the third operating mode as the second friction element becomes fully engaged whereby the downshift is shortened and traction wheel torque remains approximately unchanged at an increased level during the second operating mode. - View Dependent Claims (12)
-
Specification