Hybrid vehicle drive control system

• US 20070102207A1
• Filed: 11/06/2006
• Published: 05/10/2007
• Est. Priority Date: 11/07/2005
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Kouno, Kazuyuki, Yamanaka, Tsuyoshi, Joe, Shinichiro, Ueno, Munetoshi, Hidaka, Terumasa, Okuda, Tadashi, Adachi, Kazutaka, Itou, Ken, Tsuchikawa, Haruhisa, Onoyama, Taiichi
• Granted Patent: US 7,784,575 B2
• Time in Patent Office: Days
• US Class Current: 180/65.310
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60L 15/2036 Electric differentials, e.g. for supporting steering vehicles
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2200/26 Rail vehicles
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• 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 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• 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 2710/027 Clutch torque
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/105 Output torque
• 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

A hybrid vehicle drive control system is configured to perform engine startup when switching from an electric drive mode to a hybrid drive mode, without creating a sense of output torque loss. In particular, a controller selectively controls a first clutch disposed between the engine and the motor/generator and a second clutch disposed between the motor/generator and a drive wheel to switch between an electric drive mode in which the first clutch is released and the second clutch is engaged, and a hybrid drive mode in which both the first and second clutches are engaged. The controller sets the second torque transfer capacity to a value that is more than zero and less than the target motor/generator torque of the motor/generator when switching from the electric drive mode to the hybrid drive mode and when starting the engine.

Claims

1. A hybrid vehicle drive control system comprising:

an engine;

a motor/generator;

a first clutch configured and arranged to change a first torque transfer capacity between the engine and the motor/generator;

a second clutch configured and arranged to change a second torque transfer capacity between the motor/generator and at least one drive wheel; and

a controller configured to selectively control the first and second clutches to switch between an electric drive mode in which the first clutch is released and the second clutch is engaged, and a hybrid drive mode in which both the first and second clutches are engaged,

the controller being further configured to set the second torque transfer capacity to a value that is more than zero and less than a target motor/generator torque of the motor/generator when starting the engine during a drive mode change from the electric drive mode to the hybrid drive mode.

2. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to set the second torque transfer capacity of the second clutch by controlling the second torque transfer capacity of the second clutch when starting the engine.

3. The hybrid vehicle drive control system as recited in claim 2, wherein

the controller is further configured to set the second torque transfer capacity of the second clutch when starting the engine to a smaller value of a maximum drive force that can be generated by the motor/generator and a target vehicle drive force;

and

the controller is further configured to reduced the second torque transfer capacity of the second clutch when starting the engine to generate a prescribed slippage in the second clutch.

4. The hybrid vehicle drive control system as recited in claim 3, wherein

the controller is further configured to control the prescribed slippage in the second clutch by performing feedback control of the second torque transfer capacity of the second clutch when the second clutch is determined to be operating in a coefficient of friction stable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively gradual;

and

the controller is further configured to control the prescribed slippage in the second clutch by performing feedforward control of the second torque transfer capacity of the second clutch when the second clutch is determined to be operating in a coefficient of friction unstable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively rapid.

5. The hybrid vehicle drive control system as recited in claim 4, wherein

the controller is further configured to set the second torque transfer capacity of the second clutch to a sum of a target drive force equivalent component, the first torque transfer capacity of the first clutch, and a second clutch slip control component of the torque, when in the coefficient of friction stable region;

and

the controller is further configured to set the second torque transfer capacity of the second clutch to a sum of the target drive force equivalent component and the first torque transfer capacity of the first clutch when in the coefficient of friction unstable region.

6. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to set the second torque transfer capacity of the second clutch by controlling the target motor/generator torque of the motor/generator when starting the engine.

7. The hybrid vehicle drive control system as recited in claim 6, wherein

the controller is further configured to set the target motor/generator torque of the motor/generator to a sum of the target drive force, a first clutch transfer torque component, and the second clutch slip control component of the torque before starting the engine.

8. The hybrid vehicle drive control system as recited in claim 6, wherein

the controller is further configured to set the target motor/generator torque of the motor/generator to a sum of the target drive force, the first clutch transfer torque component, and the second clutch slip control component of the torque, minus an engine torque estimated value after starting the engine.

9. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to set the second torque transfer capacity of the second clutch by controlling at least one of the second torque transfer capacity of the second clutch and the target motor/generator torque of the motor/generator when starting the engine.

10. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to generate slippage in the second clutch by setting the second torque transfer capacity of the second clutch to the value that is less than the target motor/generator torque for engine startup, and to engage the first clutch regardless of a rotational state of the motor/generator.

11. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to selectively perform one of

first starting engagement control of the first clutch and then torque transfer capacity control of the second torque transfer capacity of the second clutch,

first start the torque transfer capacity control of the second torque transfer capacity of the second clutch and then the engagement of control of the first clutch, and

simultaneously starting the engagement control of the first clutch and the torque transfer capacity control of the second torque transfer capacity of the second clutch,

depending on whether priority is given to reducing shock or improving engine starting response due to at least one of a vehicle acceleration request, an operation state, or a transition from the electric drive mode to the hybrid drive mode.

12. The hybrid vehicle drive control system as recited in claim 11, wherein

the controller is further configured to first start performing the engagement control of the first clutch, and then the torque transfer capacity control of the second torque transfer capacity of the second clutch, upon receiving a request for rapid acceleration above a prescribed acceleration rate;

and

the controller is further configured to first the torque transfer capacity control of the second torque transfer capacity of the second clutch and then the engagement of control of the first clutch upon receiving a request for low acceleration below a prescribed acceleration rate.

13. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to set at least one of the second torque transfer capacity of the second clutch and the target motor/generator torque of the motor/generator, which are used in setting the second torque transfer capacity of the second clutch when starting the engine, to a sum of a target drive force equivalent component and a first torque transfer capacity of the first clutch when the second clutch is determined to be operating in a coefficient of friction unstable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively rapid, and

the controller is further configured to set at least one of the second torque transfer capacity of the second clutch and the target motor/generator torque of the motor/generator, which are used in setting the second torque transfer capacity of the second clutch when starting the engine, to a sum of the target equivalent component, the first torque transfer capacity of the first clutch, and a second clutch slip control component of the torque when the second clutch is determined to be operating in a coefficient of friction stable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively gradual.

14. The hybrid vehicle drive control system as recited in claim 13, wherein

the controller is further configured to selectively use one at least one of a torque transfer capacity control of the second clutch and a motor/generator torque control when in the coefficient of friction stable region to achieve the second clutch slip control component of the torque depending on whether priority is given to reducing shock or improving engine starting response due to at least one of a vehicle acceleration request, an operation state, or a transition from the electric drive mode to the hybrid drive mode.

15. The hybrid vehicle drive control system as recited in claim 14, wherein

the controller is further configured to use the torque transfer capacity control of the second clutch, upon receiving a request for rapid acceleration above a prescribed acceleration rate;

and

the controller is further configured to use the motor/generator torque control upon receiving a request for low acceleration below a prescribed acceleration rate.

16. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to engage the first clutch prior to engagement of the second clutch when switching from the electric drive mode to the hybrid drive mode has been completed after the starting the engine.

17. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to selectively perform one of

first start engaging the first clutch and then start the engine,

first start the engine and then start engaging the first clutch, and

simultaneously engaging the first clutch and starting the engine,

depending on at least one of a slipping state of the second clutch and a requested engine response when starting the engine.

18. The hybrid vehicle drive control system as recited in claim 17, wherein

the controller is further configured to first engaging the first clutch and then start the engine, upon determining that a vehicle is starting travel from a stopped state;

and

the controller is further configured to first start the engine and then start engaging the first clutch upon determining that the vehicle is traveling.

19. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to switch from a motor/generator torque control to a hybrid drive mode control when the second clutch is determined to be operating in a coefficient of friction unstable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively rapid.

20. The hybrid vehicle drive control system as recited in claim 1, wherein

the controller is further configured to switch from a second clutch torque transfer capacity control to a hybrid drive mode control when the second clutch is determined to be operating in a coefficient of friction stable region in which a change in the coefficient of friction with respect to the slippage of the second clutch is relatively gradual.

21. A hybrid vehicle drive control system comprising:

first power supply means for supplying a first source of power;

second power supply means for supplying a second source of power;

first power transfer means for selectively changing a first torque transfer capacity between the first and second power supply means;

second power transfer means for selectively changing a second torque transfer capacity between the second power supply means and at least one drive wheel of a hybrid vehicle; and

control means for selectively controlling the first and second power transfer means to switch between an electric drive mode by releasing the first power transfer means and engaging the second power transfer means, and a hybrid drive mode by engaging both the first and second power transfer means,

the control means further including a function for setting the second torque transfer capacity to a value that is more than zero and less than a target torque of the second power supply means when starting the first power supply means during a drive mode change from the electric drive mode to the hybrid drive mode.

22. A hybrid vehicle drive control method comprising:

selectively changing a first torque transfer capacity between an engine and the motor/generator using a first clutch;

selectively changing a second torque transfer capacity between the motor/generator and at least one drive wheel of a hybrid vehicle using a second clutch;

selectively controlling the first and second clutches to switch between an electric drive mode by releasing the first clutch and engaging the second clutch, and a hybrid drive mode by engaging both the first and second clutches; and

setting the second torque transfer capacity to a value that is more than zero and less than a target motor/generator torque of the motor/generator when starting the engine during a drive mode change from the electric drive mode to the hybrid drive mode.