WORK VEHICLE AND CONTROL METHOD FOR SAME

• US 20150315767A1
• Filed: 06/25/2014
• Published: 11/05/2015
• Est. Priority Date: 06/28/2013
• Status: Active Grant

• Current Assignee: Komatsu Ltd.
• Original Assignee: Komatsu Ltd.
• Inventors: MIYAMOTO, Shunsuke, MONDEN, Hiroshi, HIRAKI, Hikosaburou, FUJIWARA, Yasuo, OHKURA, Yasunori
• Granted Patent: US 9,732,499 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B60K 2006/381 characterized by driveline brakes shift brakes in transmission B60K6/54
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/485 Motor-assist type
• 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 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2200/40 Working vehicles
• CPC Class Codes: B60L 2220/42 with use of more than one motor
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/40 using propulsion power supplied by capacitors
• CPC Class Codes: B60L 50/62 charged by low-power generators primarily intended to support the batteries, e.g. range extenders
• 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 10/26 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 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 2300/17 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: B60W 2510/1005 : Transmission ratio engaged
• CPC Class Codes: B60W 2520/10 : Longitudinal speed
• CPC Class Codes: B60W 2540/10 : Accelerator pedal position
• CPC Class Codes: B60W 2540/12 : Brake pedal position
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/0677 : Engine power
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: B60W 2710/105 : Output torque
• CPC Class Codes: B60W 30/18127 : Regenerative braking
• CPC Class Codes: B60W 30/1884 : Avoiding stall or overspeed of the engine
• CPC Class Codes: B60W 50/0097 : Predicting future conditions
• CPC Class Codes: B60Y 2200/411 : Bulldozers, Graders
• CPC Class Codes: E02F 3/283 : with a single arm pivoted directly on the chassis linkage mechanism for it E02F3/3405
• CPC Class Codes: E02F 3/422 : Drive systems for bucket-arms, front-end loaders, dumpers or the like
• CPC Class Codes: E02F 9/2075 : of the hybrid type for vehicles in general B60W20/00
• CPC Class Codes: E02F 9/2079 : Control of mechanical transmission for hydrostatic transmission or hydraulic torque converter E02F9/2253
• CPC Class Codes: E02F 9/2091 : Control of energy storage means for electrical energy, e.g. battery or capacitors energy recovery arrangements in hydraulic or pneumatic drives E02F9/2217
• CPC Class Codes: F16H 2200/2007 : with two sets of orbital gears
• CPC Class Codes: F16H 3/66 : composed of a number of gear trains without drive passing from one train to another
• 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 903/93 : Conjoint control of different elements
• CPC Class Codes: Y10S 903/945 : Characterized by control of gearing, e.g. control of transmission ratio

Abstract

The power-transmission device has an input shaft, an output shaft, a gear mechanism, and a motor. The gear mechanism includes a plurality of planetary gear mechanisms and a mode-switching mechanism, and transmits the rotations of the input shaft to the output shaft. The mode-switching mechanism selectively switches the drive-power transmission path of the power-transmission device between a plurality of modes. The motor is connected to the rotating elements of the planetary gear mechanisms. A target-input-torque determination unit determines the target input torque, which is a target value for the torque to be inputted to the power-transmission device. The target-output-torque determination unit determines the target output torque, which is a target value for the torque to be outputted from the power-transmission device. The command-torque determination unit uses the torque balance information to determine torque commands to the motor from the target input torque and the target output torque.

Claims

1. A work vehicle, comprising:

an engine;

a hydraulic pump driven by the engine;

a work implement driven by hydraulic fluid discharged from the hydraulic pump;

a travel device driven by the engine;

a power-transmission device configured to transmit driving power from the engine to the travel device; and

a control unit for controlling the power-transmission device;

the power-transmission device including

an input shaft;

an output shaft;

a gear mechanism for transmitting rotation of the input shaft to the output shaft, the gear mechanism including a plurality of planetary gear mechanisms and a mode-switching mechanism for selectively switching a drive-power transmission path in the power-transmission device among a plurality of modes; and

a motor connected to a rotating element of the plurality of planetary gear mechanisms; and

,

the power-transmission device being configured so that a rotation speed ratio of the output shaft with respect to the input shaft is changed by changing a rotation speed of the motor, and

the control unit including

a target-input-torque determination unit that determines a target input torque which is a torque target value inputted to the power-transmission device;

a target-output-torque determination unit that determines a target output torque which is a torque target value outputted from the power-transmission device;

a storage unit for storing torque balance information for defining a relationship between the target input torque and the target output torque to achieve a balance of the torques of the power-transmission device; and

a command-torque determination unit that uses the torque balance information to determine a command torque for the motor from the target input torque and the target output torque.

2. The work vehicle according to claim 1, further comprising

a vehicle speed detecting unit for detecting a vehicle speed;

an accelerator operating member;

an accelerator operation detecting unit for detecting an operation amount of the accelerator operating member;

the control unit further having a transmission requirement determination unit for determining a required tractive force on the basis of the vehicle speed and the operation amount of the accelerator operating member; and

the target-output-torque determination unit determining the target output torque on the basis of the required tractive force.

3. The work vehicle according to claim 2, wherein

the transmission requirement determination unit determines the required tractive force from the vehicle speed on the basis of required tractive force characteristics that define a relationship between the vehicle speed and the required tractive force;

and

the transmission requirement determination unit determines the required tractive force characteristics in response to the operation amount of the accelerator operating member.

4. The work vehicle according to claim 3, wherein

the transmission requirement determination unit determines the required tractive force characteristics by multiplying the basic required tractive force characteristics by a tractive force ratio and a vehicle speed ratio;

and

the transmission requirement determination unit determines the tractive force ratio and the vehicle speed ratio in response to the operation amount of the accelerator operating member.

5. The work vehicle according to claim 4, further comprising

a speed change operating member;

the transmission requirement determination unit selecting the basic required tractive force characteristics in response to an operation of the speed change operating member.

6. The work vehicle according to claim 2 wherein

the required tractive force characteristics define the required tractive force that is a negative value with respect to the vehicle speed equal to or above a predetermined speed.

7. The work vehicle according to claim 2, further comprising

an energy reservoir unit for storing energy generated in the motor;

the control unit further has an energy management requirement determination unit for determining an energy management required horsepower on the basis of a remaining amount of energy in the energy reservoir unit;

the transmission requirement determination unit determining a transmission required horsepower on the basis of the vehicle speed and the operation amount of the accelerator operating member; and

the target-input-torque determination unit determining the target input torque on the basis of the transmission required horsepower and the energy management required horsepower.

8. The work vehicle according to claim 7, further comprising

a work implement operating member for operating the work implement;

the control unit further including

a work implement requirement determination unit for determining a work implement required horsepower on the basis of the operation amount of the work implement operating member; and

an engine requirement determination unit for determining an engine required horsepower on the basis of the work implement required horsepower, the transmission required horsepower, and the energy management required horsepower;

the target-input-torque determination unit determining an upper limit of the target input torque from an upper limit target input torque line and the engine rotation speed; and

the upper limit target input torque line defining, as the upper limit of the target input torque, a value that is less than the target output torque of the engine determined from the engine required horsepower and the engine rotation speed.

9. The work vehicle according to claim 8, wherein

the control unit further has a distribution ratio determination unit for determining a transmission output ratio;

and

the distribution ratio determination unit sets a value less than one as the transmission output ratio when the total of the work implement required horsepower, the transmission required horsepower, and the energy management required horsepower is larger than a predetermined load upper limit horsepower; and

the target-input-torque determination unit determines the target input torque on the basis of the energy management required horsepower and a value derived by multiplying the transmission required horsepower by the transmission output ratio.

10. The work vehicle according to claim 9, wherein

the target-output-torque determination unit determines the target output torque on the basis of a value derived by multiplying the required tractive force by the transmission output ratio.

11. The work vehicle according to claim 1, wherein

the control unit further includes

an engine requirement determination unit for determining an engine required horsepower;

and

a required throttle determination unit for determining a required throttle value,

the storage unit stores an engine torque line that defines a relationship between the output torque of the engine and the engine rotation speed, and a matching line for determining the required throttle value from the engine required horsepower;

the engine torque line includes a regulation region and a full load region;

the regulation region changes in response to the required throttle value;

the full load region includes a rated point and a maximum torque point located on the low engine rotation speed side from the rated point;

the required throttle determination unit determines the required throttle value so that the engine torque line and the matching line coincide at a matching point where the output torque of the engine becomes the torque corresponding to the engine required horsepower; and

the matching line is set to pass through a position closer to the maximum torque point than the rated point in the full load region of the engine torque line.

12. The work vehicle according to claim 11, further comprising

a work implement operating member for operating the work implement;

a vehicle speed detecting unit that detects a vehicle speed;

an accelerator operating member;

an accelerator operation detecting unit for detecting an operation amount of the accelerator operating member; and

an energy reservoir unit for storing energy generated in the motor;

the control unit further including

a work implement requirement determination unit for determining a work implement required horsepower on the basis of the operation amount of the work implement operating member;

a transmission requirement determination unit for determining a transmission required horsepower on the basis of the vehicle speed and the operation amount of the accelerator operating member; and

an energy management requirement determination unit for determining an energy management required horsepower on the basis of a remaining amount of energy in the energy reservoir unit;

the engine requirement determination unit determining the engine required horsepower on the basis of the work implement required horsepower, the transmission required horsepower, and the energy management required horsepower.

13. The work vehicle according to claim 1, wherein

the plurality of modes includes a first mode and a second mode;

and

the command-torque determination unit determines the command torque for the motor from a first torque balance information in the first mode, and determines the command torque for the motor from a second torque balance information in the second mode.

14. A method for controlling a work vehicle, the work vehicle comprising:

a power-transmission device having an input shaft;

an output shaft;

a gear mechanism for transmitting rotation of the input shaft to the output shaft, the gear mechanism including a plurality of planetary gear mechanisms and a mode-switching mechanism for selectively switching a drive-power transmission path in the power-transmission device between a plurality of modes; and

a motor connected to a rotating element of the plurality of planetary gear mechanisms, the power-transmission device configured to change a rotation speed ratio of the output shaft with respect to the input shaft by changing the rotation speed of the motor, the method comprising;

a step for determining a target input torque that is a torque target value inputted to the power-transmission device;

a step for determining a target output torque that is a torque target value outputted from the power-transmission device; and

a step for using torque balance information for defining a relationship between the target input torque and the target output torque so that a balance of the torques in the power-transmission device is achieved, to determine a command torque for the motor from the target input torque and the target output torque.