Vehicle drive system and vehicle controlling method

• US 20020123836A1
• Filed: 02/14/2002
• Published: 09/05/2002
• Est. Priority Date: 03/01/2001
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Yamaguchi, Musashi, Komiyama, Susumu, Deguchi, Yoshitaka
• Granted Patent: US 6,662,096 B2
• Time in Patent Office: Days
• US Class Current: 701/51
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• 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 2240/443 Torque
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60W 10/04 including control of propulsion units
• 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 10/105 of electric type
• 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 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/242 : for electrical energy
• CPC Class Codes: B60W 2510/305 : Power absorbed by auxiliaries
• CPC Class Codes: B60W 2520/10 : Longitudinal speed
• CPC Class Codes: B60W 2540/10 : Accelerator pedal position
• CPC Class Codes: B60W 2552/15 : Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/1011 : Input shaft speed, e.g. turbine speed
• CPC Class Codes: B60W 2710/1061 : Output power
• CPC Class Codes: B60W 30/1882 : characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: F16H 61/662 : with endless flexible members
• CPC Class Codes: Y02T 10/40 : Engine management systems
• 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
• CPC Class Codes: Y02T 10/84 : Data processing systems or methods, management, administration
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/918 : Continuously variable
• CPC Class Codes: Y10S 903/945 : Characterized by control of gearing, e.g. control of transmission ratio

Abstract

A minimum needed power is computed by adding a reserve drive power to a target drive power, a best fuel cost-performance rotation speed is computed based on the target drive power and the best fuel cost-performance power characteristics of an engine (1), and a minimum needed rotation speed is computed based on the minimum needed power and the maximum power characteristics of the engine (1). The best fuel cost-performance rotation speed is compared with the minimum needed rotation speed, the larger is selected as a target input rotation speed of a continuously variable transmission (2), the speed ratio of the transmission (2) is controlled based on the driving axe rotation speed and target input rotation speed, and the torque of the engine (2) is controlled based on the engine rotation speed and target drive power.

Claims

1. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a continuously variable transmission provided between the engine and the drive wheel,

a sensor which detects an accelerator depression amount,

a sensor which detects a vehicle speed,

a sensor which detects an engine rotation speed, and

a controller functioning to;

compute a target drive power based on the accelerator depression amount and vehicle speed,

set a reserve drive power for vehicle acceleration,

compute a minimum needed power by adding the reserve drive power to the target drive power,

compute a best fuel cost-performance rotation speed based on the target drive power and best fuel cost-performance power characteristics of the engine,

compute a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

compare the best fuel cost-performance rotation speed and minimum needed rotation speed, and select the larger as the target input rotation speed of the transmission,

control the speed ratio of the transmission based on the vehicle speed and target input rotation speed, and

control the torque of the engine based on the engine rotation speed and target drive power.

2. The drive system as defined in claim 1, wherein the controller further functions to:

store a relation between the engine power and the best fuel cost-performance rotation speed of the engine, and

compute the best fuel cost-performance rotation speed based on the target drive power and the stored relation.

3. The drive system as defined in claim 1, wherein the controller further functions to:

store a relation between the engine rotation speed and the maximum power of the engine, and

compute the minimum needed rotation speed based on the minimum needed power and the stored relation.

4. The drive system as defined in claim 1, wherein:

the transmission comprises a generator connected to the engine and a motor connected to the drive wheel, and the controller further functions to;

control the torque of the motor based on the motor rotation speed and target drive, power, and

control the rotation speed of the generator based on the target input rotation speed.

5. The drive system as defined in claim 1, wherein the controller further functions to:

determine a running mode of the vehicle, and

modify the reserve drive power according to the running mode.

6. The drive system as defined in claim 1, wherein the controller further functions to:

determine a gradient of a road, and

modify the reserve drive power according to the gradient.

7. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a generator connected to the engine,

a motor connected to the drive wheel,

a battery electrically connected to the generator and the motor,

a sensor which detects an accelerator depression amount,

a sensor which detects a vehicle speed,

a sensor which detects an engine rotation speed,

a sensor which detects a motor rotation speed and

a controller functioning to;

compute a target drive power based on the accelerator depression amount and vehicle speed,

compute a required motor power by correcting the target drive power by the efficiency of the motor,

set a target generated power according to the required motor power,

compute a target engine power by correcting the target generated power by the efficiency of the generator,

set a reserve drive power for vehicle acceleration,

compute a minimum needed power by adding the reserve drive power to the target engine power,

compute a best fuel cost-performance rotation speed based on the target engine power and best fuel cost-performance power characteristics of the engine,

compute a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

compare the best fuel cost-performance rotation speed and minimum needed rotation speed, and select the larger as the target rotation speed of the generator,

control the torque of the motor based on the motor rotation speed and target drive power,

control the rotation speed of the generator based on the target rotation speed, and

control the torque of the engine based on the engine rotation speed and target engine power.

8. The drive system as defined in claim 7, further comprising;

a sensor which detects the state of charge of the battery,

wherein the controller further functions to;

compute a target charge and discharge power of the battery based on the state of charge of the battery, and

set a value obtained by adding the target charge and discharge power to the required motor power, as the target generated power.

9. The drive system as defined in claim 7, wherein the controller further functions to:

compute the minimum needed power by subtracting the available discharge power of the battery from a value obtained by adding the reserve drive power to the target engine power.

10. The drive system as defined in claim 7, further comprising:

an auxiliary device,

wherein the controller further functions to;

compute a power consumption of the auxiliary device, and

correct the target drive power by the power consumption of the auxiliary device.

11. The drive system as defined in claim 7, wherein the controller further functions to:

determine a running mode of the vehicle, and

modify the reserve drive power according to the running mode.

12. The drive system as defined in claim 7, wherein the controller further functions to:

determine a gradient of a road, and

modify the reserve drive power according to the gradient.

14. The drive system as defined in claim 13, wherein the controller further functions to:

set an engine start power which is required to start the engine,

compute a power required to run only under the motor by adding the engine start power to a value obtained by adding the reserve drive power to the target engine power,

determine whether or not to prohibit motor running wherein the vehicle runs only under the motor by comparing the available discharge power of the battery with the power required to run only under the motor, and

set the final value of the target engine power to zero when motor running is permitted.

15. The drive system as defined in claim 13, wherein the controller further functions to:

set an engine start power which is required to start the engine,

compute a power required to run only under the motor by adding the engine start power to a value obtained by adding the reserve drive power to the target engine power,

determine whether or not to prohibit motor running wherein the vehicle runs only under the motor by comparing the available discharge power of the battery with the power required to run only under the motor, and

start the engine when the engine has stopped, when motor running is prohibited.

16. The drive system as defined in claim 13, further comprising:

an auxiliary device,

wherein the controller further functions to;

compute a power consumption of the auxiliary device, and

correct the target drive power by the power consumption of the auxiliary device.

17. The drive system as defined in claim 13, wherein the controller further functions to:

determine a running mode of the vehicle, and

modify the reserve drive power according to the running mode.

18. The drive system as defined in claim 13, wherein the controller further functions to:

determine a gradient of a road, and

modify the reserve drive power according to the gradient.

13. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a continuously variable transmission provided between the engine and the drive wheel,

a motor connected to either one of the engine and drive wheel,

a battery electrically connected to the motor,

a sensor which detects an accelerator depression amount,

a sensor which detects a vehicle speed,

a sensor which detects an engine rotation speed, and

a controller functioning to;

compute a target drive power based on the accelerator depression amount and vehicle speed,

set a target engine power according to the target drive power,

set a reserve drive power for vehicle acceleration,

compute a minimum needed power by subtracting an available discharge power of the battery from a value obtained by adding the reserve drive power to the target engine power,

compute a best fuel cost-performance rotation speed based on the target engine power and the best fuel cost-performance power characteristics of the engine,

compute a minimum needed rotation speed based on the minimum needed power and the maximum power characteristics of the engine,

compare the best fuel cost-performance rotation speed and minimum needed rotation speed, and select the larger as the target input rotation speed of the transmission,

compute the maximum power of the engine based on the engine rotation speed,

compare the target engine power with the maximum engine power, and select the smaller as a final value of the target engine power,

control the torque of the motor based on the target drive power and the final value of the target engine power, and

control the torque of the engine based on the engine rotation speed and the final value of the target engine power.

19. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a continuously variable transmission provided between the engine and the drive wheel,

means for detecting an accelerator depression amount,

means for detecting a vehicle speed,

means for detecting an engine rotation speed,

means for computing a target drive power based on the accelerator depression amount and vehicle speed,

means for setting a reserve drive power for vehicle acceleration,

means for computing a minimum needed power by adding the reserve drive power to the target drive power,

means for computing a best fuel cost-performance rotation speed based on the target drive power and best fuel cost-performance power characteristics of the engine,

means for computing a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

means for comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and selecting the larger as the target input rotation speed of the transmission,

means for controlling the speed ratio of the transmission based on the vehicle speed and target input rotation speed, and

means for controlling the torque of the engine based on the engine rotation speed and target drive power.

20. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a generator connected to the engine,

a motor connected to the drive wheel,

a battery electrically connected to the generator and the motor,

means for detecting an accelerator depression amount,

means for detecting a vehicle speed,

means for detecting an engine rotation speed,

means for detecting a motor rotation speed,

means for computing a target drive power based on the accelerator depression amount and vehicle speed,

means for computing a required motor power by correcting the target drive power by the efficiency of the motor,

means for setting a target generated power according to the required motor power,

means for computing a target engine power by correcting the target generated power by the efficiency of the generator,

means for setting a reserve drive power for vehicle acceleration,

means for computing a minimum needed power by adding the reserve drive power to the target engine power,

means for computing a best fuel cost-performance rotation speed based on the target engine power and best fuel cost-performance power characteristics of the engine,

means for computing a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

means for comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and selecting the larger as the target rotation speed of the generator,

means for controlling the torque of the motor based on the motor rotation speed and target drive power,

means for controlling the rotation speed of the generator based on the target rotation speed, and

means for controlling the torque of the engine based on the engine rotation speed and target engine power.

21. A drive system for a vehicle, comprising:

an engine,

a drive wheel,

a continuously variable transmission provided between the engine and the drive wheel,

a motor connected to either one of the engine and drive wheel,

a battery electrically connected to the motor,

means for detecting an accelerator depression amount,

means for detecting a vehicle speed,

means for detecting an engine rotation speed,

means for computing a target drive power based on the accelerator depression amount and vehicle speed,

means for setting a target engine power according to the target drive power,

means for setting a reserve drive power for vehicle acceleration,

means for computing a minimum needed power by subtracting an available discharge power of the battery from a value obtained by adding the reserve drive power to the target engine power,

means for computing a best fuel cost-performance rotation speed based on the target engine power and the best fuel cost-performance power characteristics of the engine,

means for computing a minimum needed rotation speed based on the minimum needed power and the maximum power characteristics of the engine,

means for comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and select the larger as the target input rotation speed of the transmission,

means for computing the maximum power of the engine based on the engine rotation speed,

means for comparing the target engine power with the maximum engine power, and selecting the smaller as a final value of the target engine power,

means for controlling the torque of the motor based on the target drive power and the final value of the target engine power, and

means for controlling the torque of the engine based on the engine rotation speed and the final value of the target engine power.

22. A vehicle control method used for a vehicle including an engine, a drive wheel, a continuously variable transmission provided between the engine and the drive wheel, the method comprising:

computing a target drive power based on an accelerator depression amount and vehicle speed,

setting a reserve drive power for vehicle acceleration,

computing a minimum needed power by adding the reserve drive power to the target drive power,

computing a best fuel cost-performance rotation speed based on the target drive power and best fuel cost-performance power characteristics of the engine,

computing a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and selecting the larger as the target input rotation speed of the transmission,

controlling the speed ratio of the transmission based on the vehicle speed and target input rotation speed, and

controlling the torque of the engine based on an engine rotation speed and target drive power.

23. A vehicle control method used for a vehicle including an engine, a drive wheel, a generator connected to the engine, a motor connected to the drive wheel, a battery electrically connected to the generator and the motor, the method comprising:

computing a target drive power based on an accelerator depression amount and vehicle speed,

computing a required motor power by correcting the target drive power by the efficiency of the motor,

setting a target generated power according to the required motor power,

computing a target engine power by correcting the target generated power by the efficiency of the generator,

setting a reserve drive power for vehicle acceleration,

computing a minimum needed power by adding the reserve drive power to the target engine power,

computing a best fuel cost-performance rotation speed based on the target engine power and best fuel cost-performance power characteristics of the engine,

computing a minimum needed rotation speed based on the minimum needed power and maximum power characteristics of the engine,

comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and selecting the larger as the target rotation speed of the generator,

controlling the torque of the motor based on a motor rotation speed and target drive power,

controlling the rotation speed of the generator based on the target rotation speed, and

controlling the torque of the engine based on an engine rotation speed and target engine power.

24. A vehicle control method used for a vehicle including an engine, a drive wheel, a continuously variable transmission provided between the engine and the drive wheel, a motor connected to either one of the engine and drive wheel, a battery electrically connected to the motor, the method comprising:

computing a target drive power based on an accelerator depression amount and vehicle speed,

setting a target engine power according to the target drive power,

setting a reserve drive power for vehicle acceleration,

computing a minimum needed power by subtracting an available discharge power of the battery from a value obtained by adding the reserve drive power to the target engine power,

computing a best fuel cost-performance rotation speed based on the target engine power and the best fuel cost-performance power characteristics of the engine,

computing a minimum needed rotation speed based on the minimum needed power and the maximum power characteristics of the engine,

comparing the best fuel cost-performance rotation speed and minimum needed rotation speed, and select the larger as the target input rotation speed of the transmission,

computing the maximum power of the engine based on an engine rotation speed,

comparing the target engine power with the maximum engine power, and selecting the smaller as a final value of the target engine power,

controlling the torque of the motor based on the target drive power and the final value of the target engine power, and

controlling the torque of the engine based on the engine rotation speed and the final value of the target engine power.