SYSTEM AND METHOD FOR CONTROLLING OPERATION OF AN ELECTRIC ALL-WHEEL DRIVE HYBRID VEHICLE

• US 20120271494A1
• Filed: 04/22/2011
• Published: 10/25/2012
• Est. Priority Date: 04/22/2011
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Kim, Min-Joong, Swales, Shawn H., Schoenek, Norman
• Granted Patent: US 8,447,451 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 2007/0092 the motor axle being coaxial to the wheel axle
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60K 6/52 Driving a plurality of drive axles, e.g. four-wheel drive
• CPC Class Codes: B60K 7/0007 the motor being electric
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/115 with planetary gears
• CPC Class Codes: B60W 10/30 including control of auxiliary equipment, e.g. air-conditioning compressors or oil pumps
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2710/0627 Fuel flow rate
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method of controlling operation of an electric all-wheel drive hybrid vehicle having an engine, automatic transmission, and first and second motor-generators includes driving the vehicle via the second motor-generator. The method also includes determining desired engine speed and transmission gear ratio. The method also includes starting the engine via the first motor-generator and locking up all but one of a plurality of transmission torque transmitting devices required to be engaged for selecting the gear ratio. The method additionally includes modulating engagement of the one remaining torque transmitting device while controlling the engine to generate the desired engine speed. Furthermore, the method includes regulating the engine and the first motor-generator such that their combined torque is approximately zero, locking up the remaining torque transmitting device to select the gear ratio, and controlling the engine to generate desired transmission output torque. A system for controlling such a vehicle is also disclosed.

Claims

1. A method of controlling operation of an electric all-wheel drive hybrid vehicle having an internal combustion engine configured to drive the vehicle via a first set of wheels through an automatic transmission, a first motor-generator configured to start the engine, and a second motor-generator configured to drive the vehicle via a second set of wheels, the method comprising:

driving the vehicle solely via the second motor-generator while the engine is off;

receiving a request for the engine to be started for generating a desired level of transmission output torque;

determining a desired engine speed and a gear ratio in the transmission according to the desired level of transmission output torque;

starting the engine via the first motor-generator for generating the desired level of transmission output torque;

locking up all but one of a plurality of transmission torque transmitting devices required to be engaged for selecting the gear ratio;

modulating the engagement of the one remaining torque transmitting device of the plurality of torque transmitting devices such that a torque capacity of the one remaining torque transmitting device is gradually increased;

controlling the engine to generate the desired engine speed while the engagement of the one remaining torque transmitting device is being modulated;

regulating the engine and the first motor-generator such that combined torque input from the engine and the first motor-generator to the transmission is approximately zero;

locking up the one remaining torque transmitting device to select the gear ratio; and

controlling the engine to generate the desired level of transmission output torque.

2. The method of claim 1, wherein the first motor-generator is configured as one of an integrated starter-generator (ISG) and a 12 volt stop-start motor.

3. The method of claim 1, wherein said controlling the engine to generate the desired engine speed is accomplished by controlling engine torque via at least one of regulating engine fuel rate, retarding engine spark, and regulating the torque of the first motor-generator.

4. The method of claim 1, wherein said controlling the engine to generate the desired level of transmission output torque is accomplished via at least one of regulating engine fuel rate, advancing engine spark, and regulating the torque of the first motor-generator.

5. The method of claim 1, wherein said controlling the engine to generate the desired level of transmission output torque is accomplished to drive the vehicle in an electric all-wheel drive mode.

6. The method of claim 1, wherein said controlling the engine to generate the desired level of transmission output torque is accomplished to drive the vehicle in an engine-only drive mode.

7. The method of claim 6, further comprising phasing out the second motor-generator while the engine is being controlled to generate the desired level of transmission output torque in the engine-only drive mode.

8. The method of claim 7, wherein the vehicle includes an energy storage device configured to supply energy to the second motor-generator, and said comprising phasing out the second motor-generator is accomplished when the energy supplied to the second motor-generator by the energy storage device is below a predetermined value.

9. The method of claim 6, wherein the vehicle includes a controller configured to receive the request for the engine to be started for generating a desired level of transmission output torque, and wherein the controller is programmed to execute each of said determining the desired engine speed and the gear ratio in the transmission, starting the engine via the first motor-generator, locking up all but one of a plurality of torque transmitting devices, modulating the engagement of the remaining one torque transmitting device, controlling the engine to generate the desired engine speed, regulating the engine and the first motor-generator such that combined torque input from the engine and the first motor-generator to the transmission is approximately zero, locking up the remaining torque transmitting device, controlling the engine to generate the desired level of transmission output torque, and phasing out the second motor-generator.

10. The method of claim 1, wherein the vehicle includes a single fluid pump configured to apply the plurality of transmission torque transmitting devices.

11. A system for controlling operation of an electric all-wheel drive hybrid vehicle, the system comprising:

an internal combustion engine configured to drive the vehicle via a first set of wheels through an automatic transmission, wherein the transmission includes a plurality of torque transmitting devices required to be engaged for selecting a gear ratio;

a first motor-generator configured to start the engine;

a second motor-generator configured to drive the vehicle via a second set of wheels;

a controller configured to receive a request for the engine to be started when the vehicle is being driven solely via the second motor-generator, to control the engine to generate a desired level of transmission output torque, and configured to;

determine a desired engine speed and a gear ratio in the transmission according to the desired level of transmission output torque;

start the engine via the first motor-generator for generating the desired level of transmission output torque;

lock up all but one of a plurality of transmission torque transmitting devices required to be engaged for selecting the gear ratio;

modulate the engagement of the one remaining torque transmitting device of the plurality of torque transmitting devices such that a torque capacity of the one remaining torque transmitting device is gradually increased;

control the engine to generate the desired engine speed while the engagement of the one remaining torque transmitting device is being modulated;

regulate the engine and the first motor-generator such that combined torque input from the engine and the first motor-generator to the transmission is approximately zero;

lock up the one remaining torque transmitting device to select the gear ratio; and

control the engine to generate the desired level of transmission output torque.

12. The system of claim 11, wherein the first motor-generator is configured as one of an integrated starter-generator (ISG) and a 12 volt stop-start motor.

13. The system of claim 11, wherein the controller is configured to control the engine to generate the desired engine speed by controlling engine torque via at least one of regulating engine fuel rate, retarding engine spark, and regulating the torque of the first motor-generator.

14. The system of claim 11, wherein the controller is configured to control the engine to generate the desired level of transmission output torque via at least one of regulating engine fuel rate, advancing engine spark, and regulating the torque of the first motor-generator.

15. The system of claim 11, wherein the desired level of transmission output torque is for driving the vehicle in an electric all-wheel drive mode.

16. The system of claim 11, wherein the desired level of transmission output torque is for driving the vehicle in an engine-only drive mode.

17. The system of claim 16, wherein the controller is additionally programmed to phase out the second motor-generator while the engine is being controlled to generate the desired level of transmission output torque in the engine-only drive mode.

18. The system of claim 17, further comprising an energy storage device configured to supply energy to the second motor-generator, wherein the second motor-generator is phased out when the energy supplied to the second motor-generator by the energy storage device is below a predetermined value.

19. The system of claim 11, wherein the vehicle includes a single fluid pump configured to apply the plurality of transmission torque transmitting devices.

20. An electric all-wheel drive hybrid vehicle comprising:

an internal combustion engine configured to drive the vehicle via a first set of wheels through an automatic transmission, wherein the transmission includes a plurality of torque transmitting devices required to be engaged for selecting a gear ratio;

a first motor-generator configured to start the engine;

a second motor-generator configured to drive the vehicle via a second set of wheels;

a controller configured to receive a request for the engine to be started when the vehicle is being driven solely via the second motor-generator, to control the engine to generate a desired level of transmission output torque, and configured to;

determine a desired engine speed and a gear ratio in the transmission according to the desired level of transmission output torque;

start the engine via the first motor-generator for generating the desired level of transmission output torque;

lock up all but one of a plurality of transmission torque transmitting devices required to be engaged for selecting the gear ratio;

modulate the engagement of the one remaining torque transmitting device of the plurality of torque transmitting devices such that a torque capacity of the one remaining torque transmitting device is gradually increased;

control the engine via retarding engine spark to generate the desired engine speed while the engagement of the one remaining torque transmitting device is being modulated;

regulate the engine and the first motor-generator such that combined torque input from the engine and the first motor-generator to the transmission is approximately zero;

lock up the one remaining torque transmitting device to select the gear ratio; and

control the engine via advancing engine spark to generate the desired level of transmission output torque.