Hybrid vehicle drive force control device and control method

• US 6,090,007 A
• Filed: 03/18/1999
• Issued: 07/18/2000
• Est. Priority Date: 03/20/1998
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Uchida, Masaaki, Katakura, Shusaku, Nakajima, Yuki
• Primary Examiner(s): Marmor, Charles A
• Assistant Examiner(s): HO, HA DINH
• Application Number:
  US09/271,337
• Time in Patent Office: 488 Days
• Field of Search: 477/2, 477/3, 477/15, 477/44, 477/46, 180/65.2, 180/65.3, 180/65.4, 180/65.5, 180/65.6
• US Class Current: 477/46
• CPC Class Codes: B60K 6/485 Motor-assist type
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/427 Voltage
• CPC Class Codes: B60L 2240/429 Current
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/443 Torque
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2250/28 Accelerator pedal thresholds
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 3/0046 relating to electric energy storage systems, e.g. batteries or capacitors
• CPC Class Codes: B60L 50/15 with additional electric power supply with capacitors charged by engine-driven generators B60L50/40; with batteries charged by engine-driven generators B60L50/61
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 58/26 by cooling
• 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 10/10 : including control of change-speed gearings
• CPC Class Codes: B60W 10/26 : for electrical energy, e.g. batteries or capacitors
• 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 2540/10 : Accelerator pedal position
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 2710/105 : Output torque
• CPC Class Codes: F16H 61/66 : specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• 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: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/905 : Combustion engine
• CPC Class Codes: Y10S 903/907 : Electricity storage, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/909 : Gearing
• 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

In a hybrid vehicle wherein the rotation torque of a motor and engine are input to a continuously variable transmission, a target speed ratio is determined from a target engine rotation speed set based on a target drive torque of said vehicle and a vehicle speed. A target combined torque of the motor and engine is set based on the target drive torque and a real speed ratio of the transmission. A target motor torque is determined based on the target combined torque and the input rotation speed of the continuously variable transmission. A value obtained by subtracting the target motor torque from the target combined torque is set equal to a target engine torque. The drive force of the hybrid vehicle is optimized by controlling the engine, motor and continuously variable transmission by the target engine torque, target motor torque and target speed ratio thus obtained.

Claims

1. A hybrid vehicle drive force control device for controlling, according to a depression of an accelerator pedal, an output torque of an engine, an output torque of a motor which varies according to a supply current from a battery, and a speed ratio of a continuously variable transmission which is connected to said engine and said motor, comprising:

a sensor for detecting a depression amount of said accelerator pedal,

a sensor for detecting a vehicle speed,

a sensor for detecting an input rotation speed of said continuously variable transmission,

a sensor for detecting an output rotation speed of said continuously variable transmission,

an engine controller for varying said output torque of said engine based on a target engine torque,

a motor controller for varying said output torque of said motor based on a target motor torque,

a speed ratio controller for varying said speed ratio of said continuously variable transmission based on a target speed ratio, and

a microprocessor programmed to;

set a target drive torque of said vehicle based on said depression amount of said accelerator pedal and said vehicle speed,

set a target engine rotation speed based on said target drive torque,

set said target speed ratio based on said target engine rotation speed and said vehicle speed,

calculate a real speed ratio of said continuously variable transmission from the input rotation speed and output rotation speed of said continuously variable transmission,

set a target combined torque of said engine and said motor based on said target drive torque and said real speed ratio,

set said target motor torque based on said target combined torque and said input rotation speed, and

set said target engine torque based on the difference of said target combined torque and said target motor torque.

2. A drive force control device as defined in claim 1, wherein said motor comprises a motor/generator which operates as a generator according to the input of a rotation torque from said continuously variable transmission.

3. A drive force control device as defined in claim 1, wherein said microprocessor is further programmed to set said target drive torque to be larger when a depression amount of said accelerator pedal is larger, and to set said target drive torque to be smaller when said vehicle speed is slower.

4. A drive force control device as defined in claim 1, wherein said microprocessor is further programmed to set said target engine torque equal to a value obtained by dividing a difference of said target combined torque and said target motor torque, by a torque ratio equal to the inverse of the ratio of the rotation speed of said engine and the input rotation speed of said continuously variable transmission.

5. A drive force control device as defmed in claim 1, wherein said microprocessor is further programmed to set said target combined torque equal to a value obtained by dividing said target drive torque by said real speed ratio.

6. A drive force control device as defined in claim 1, wherein said microprocessor is further programmed to set said target engine rotation speed to be larger when said target drive torque is larger.

7. A drive force control device as defined in claim 1, wherein said microprocessor is further programmed to set said target motor torque to be larger when said target combined torque is larger.

8. A drive force control device as defined in claim 1, wherein said microprocessor is further programmed to store a map which defines the relation of said target drive torque and said target engine rotation speed so as to be able to realize a predetermined power with minimum fuel consumption, and is further programmed to determine said target engine rotation speed based on said target drive torque and said map.

9. A drive force control device as defined in claim 1, wherein said device further comprises a sensor for detecting a charge amount of said battery, and said microprocessor is further programmed to limit a maximum value of said target motor torque to a smaller value, when said battery charge amount is smaller.

10. A drive force control device as defined in claim 1, wherein said device further comprises a sensor for detecting the charge amount of said battery, and said microprocessor is further programmed to set said target engine rotation speed to be lower for the same target drive torque, when said battery charge amount is larger.

11. A hybrid vehicle drive force control device for controlling, according to a depression of an accelerator pedal, an output torque of an engine, an output torque of a motor which varies according to a supply current from a battery, and a speed ratio of a continuously variable transmission which is connected to said engine and said motor, comprising:

means for detecting a depression amount of said accelerator pedal,

means for detecting a vehicle speed,

means for detecting an input rotation speed of said continuously variable transmission,

means for detecting an output rotation speed of said continuously variable transmission,

means for setting a target drive torque of said vehicle based on said depression amount of said accelerator pedal and said vehicle speed

means for setting a target engine rotation speed based on said target drive torque,

means for setting a target speed ratio based on said target engine rotation speed and said vehicle speed,

means for calculating a real speed ratio of said continuously variable transmission from the input rotation speed and output rotation speed of said continuously variable transmission,

means for setting a target combined torque of said engine and said motor based on said target drive torque and said real speed ratio,

means for setting a target motor torque based on said target combined torque and said input rotation speed, and

means for setting a target engine torque based on the difference of said target combined torque and said target motor torque,

means for varying an output torque of said engine based on said target engine torque,

means for varying said output torque of said motor based on said target motor torque, and

means for varying a speed ratio of said continuously variable transmission based on said target speed ratio.

12. A hybrid vehicle drive force control method for controlling, according to a depression of an accelerator pedal, an output torque of an engine, an output torque of a motor which varies according to a supply current from a battery, and a speed ratio of a continuously variable transmission which is connected to said engine and said motor, comprising:

detecting a depression amount of said accelerator pedal,

detecting a vehicle speed,

detecting an input rotation speed of said continuously variable transmission,

detecting an output rotation speed of said continuously variable transmission,

setting a target drive torque of said vehicle based on said depression amount of said accelerator pedal and said vehicle speed,

setting a target engine rotation speed based on said target drive torque,

setting a target speed ratio based on said target engine rotation speed and said vehicle speed,

calculating a real speed ratio of said continuously variable transmission from the input rotation speed and output rotation speed of said continuously variable transmission,

setting a target combined torque of said engine and said motor based on said target drive torque and said real speed ratio,

setting a target motor torque based on said target combined torque and said input rotation speed,

setting a target engine torque based on the difference of said target combined torque and said target motor torque,

varying an output torque of said engine based on said target engine torque,

varying said output torque of said motor based on sad target motor torque, and

varying a speed ratio of said continuously variable transmission based on said target speed ratio.