Engine controlling device and method for a hybrid vehicle

• US 20070199745A1
• Filed: 02/27/2007
• Published: 08/30/2007
• Est. Priority Date: 02/28/2006
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Hayashi, Nobuki
• Granted Patent: US 7,770,675 B2
• Time in Patent Office: Days
• US Class Current: 180/65.28
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/182 Brake pressure, e.g. of fluid or between pad and disc
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2530/16 Driving resistance
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/18027 : Drive off, accelerating from standstill
• CPC Class Codes: B60W 30/18118 : Hill holding
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility

Abstract

An engine controlling device and method for a hybrid vehicle that includes an engine and a motor-generator as driving sources and has an electric-vehicle (EV) drive mode in which the vehicle is driven using only the motor-generator as a driving source and a hybrid (HEV) drive mode in which the vehicle is driven while including the engine as a driving source. When the vehicle is in a stopped state while the driving force of the engine is not being used, the device estimates a minimum driving torque required for starting the vehicle from the relationships among a brake torque, a motor-generator torque and a vehicle speed during a transitional period of a brake-pedal releasing operation. Based on the estimated minimum driving torque, the device determines prior to pressing of the accelerator pedal whether it is necessary to use the engine for a driving force of the hybrid vehicle.

Claims

1. A controlling device for a hybrid vehicle, comprising:

an engine;

a motor-generator;

wheels for moving the hybrid vehicle;

a brake for braking the wheels; and

a controller operable to;

estimate an estimated driving force required for a forward movement of the vehicle when the brake is to be released from a state where the vehicle is stopped by the brake, the estimated driving force based on relationships among a braking force of the brake, a driving force of the motor-generator, and a vehicle speed; and

determine whether to use the engine for a driving force of the hybrid vehicle based on the estimated driving force.

2. The controlling device for the hybrid vehicle according to claim 1 wherein the controller is further operable to start the engine when the controller determines that it is necessary to use the driving force of the engine.

3. The controlling device for the hybrid vehicle according to claim 2 wherein the controller is further operable to cancel the start of the engine after the controller determines that it is necessary to use the driving force of the engine if the brake is re-pressed within a predetermined time period.

4. The controlling device for the hybrid vehicle according to claim 1 wherein the estimated driving force is based on a total torque of a brake torque and a motor-generator torque when the vehicle speed is a negative value.

5. The controlling device for the hybrid vehicle according to claim 4 wherein the controller is further operable to use the driving force of the engine if the total torque is greater than a predetermined torque value.

6. The controlling device for the hybrid vehicle according to claim 5 wherein the predetermined torque value comprises a maximum driving torque of the motor-generator.

7. The controlling device for the hybrid vehicle according to claim 5 wherein the predetermined torque value is equal to a value of a current motor-generator torque subtracted from a predetermined maximum driving torque of the motor-generator.

8. The controlling device for the hybrid vehicle according to claim 4 wherein the controller is further operable to determine that it is not necessary to use the driving force of the engine if the total torque is equal to or less than a predetermined torque value.

9. The controlling device for the hybrid vehicle according to claim 8 wherein the predetermined torque value comprises a predetermined maximum driving torque of the motor-generator.

10. The controlling device for the hybrid vehicle according to claim 1 wherein the controller is further operable to determine that it is not necessary to use the driving force of the engine if the vehicle speed is zero or higher when the brake is to be released from the state where the vehicle is stopped by the brake.

11. The controlling device for the hybrid vehicle according to claim 1, further comprising:

a first clutch interposed between the engine and the motor-generator, the first clutch being capable of changing a torque transfer capacity; and

wherein the controller is further operable to allow engagement of the first clutch when the controller determines it is necessary to use the driving force of the engine.

12. The controlling device for the hybrid vehicle according to claim 11 wherein the controller is further operable to start the engine using the motor-generator when the first clutch becomes engaged in a state where the engine is not rotating.

13. A controlling device for a hybrid vehicle having an engine, a motor-generator and a brake for braking wheels of the hybrid vehicle, the device comprising:

means for estimating an estimated driving force required for a forward movement of the vehicle when the brake is to be released where the vehicle is stopped by the brake;

wherein the estimated driving force is based on relationships among a braking force of the brake, a driving force of the motor-generator and a vehicle speed; and

means for determining whether to use the engine for a driving force of the hybrid vehicle based on the estimated driving force.

14. A method for controlling a hybrid vehicle having an engine, a motor-generator and a brake for braking wheels of the hybrid vehicle, the method comprising:

estimating an estimated driving force required for a forward movement of the vehicle when the brake is to be released where the vehicle is stopped by the brake;

wherein the estimated driving force is based on relationships among a braking force of the brake, a driving force of the motor-generator and a vehicle speed; and

determining whether to use the engine for a driving force of the hybrid vehicle based on the estimated driving force.

15. The method according to claim 14 wherein the estimated driving force is based on a total torque of a brake torque and a motor-generator torque when the vehicle speed is a negative value and wherein determining whether to use the engine for the driving force based on the estimate driving force further comprises:

using the driving force of the engine if the total torque is greater than a predetermined torque value.

16. The method according to claim 15 wherein the predetermined torque value comprises a maximum driving torque of the motor-generator.

17. The method according to claim 15, further comprising:

subtracting a current motor-generator torque from a predetermined maximum driving torque of the motor-generator;

wherein a result of the subtracting step is the predetermined torque value.

18. The method according to claim 14 wherein the estimated driving force is based on a total torque of a brake torque and a motor-generator torque when the vehicle speed is a negative value and wherein determining whether to use the engine for the driving force based on the estimate driving force further comprises:

determining that it is not necessary to use the driving force of the engine if the total torque is equal to or less than a predetermined torque value.

19. The method according to claim 14 wherein determining whether to use the engine for the driving force based on the estimated driving force further comprises:

deciding to start the engine when the estimated driving force is below a necessary force; and

canceling the start of the engine if the brake is re-pressed within a predetermined time period after deciding to start the engine.

20. The method according to claim 14, the hybrid vehicle having a first clutch interposed between the engine and the motor-generator;

and wherein determining whether to use the engine for the driving force based on the estimated driving force further comprises;

allowing engagement of the first clutch when the estimated driving force is below a necessary force.