Work vehicle and control method for same

• US 10,407,864 B2
• Filed: 06/25/2014
• Issued: 09/10/2019
• 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
• Primary Examiner(s): Scott, Jacob S.
• Assistant Examiner(s): Butler, Michael E
• Application Number:
  US14/653,485
• Publication Number:
  US 20150322645A1
• Time in Patent Office: 1,903 Days
• Field of Search: 701 50
• 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 work implement requirement determination unit determines a work implement required horsepower on the basis of an operation amount of a work implement operating member and a hydraulic pressure of a hydraulic pump. A transmission requirement determination unit determines a transmission required horsepower on the basis of a vehicle speed and the operation amount of the accelerator operating member. An engine requirement determination unit determines an engine required horsepower on the basis of the work implement required horsepower and the transmission required horsepower. The required throttle determination unit determines a required throttle value based on an engine requirement.

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 work implement operating member for operating the work implement;

a pressure sensor for detecting a hydraulic pressure of 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;

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; and

a control unit configured to control the power-transmission device;

the power-transmission device including

an input shaft;

an output shaft;

a gear mechanism including a planetary gear mechanism, the gear mechanism being configured to transmit rotation of the input shaft to the output shaft;

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

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

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

the control unit 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 the hydraulic pressure of the hydraulic pump;

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;

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

a required throttle determination unit for determining a required throttle value based on the engine required horsepower;

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;

a distribution ratio determination unit for determining a transmission output ratio, dividing the work implement required horsepower and the transmission required horsepower into respective priority portions and respective ratio portions, prioritizing the priority portions of the work implement required horsepower and the transmission required horsepower over the ratio portions of the work implement required horsepower and the transmission required horsepower, and maintaining the priority portions of the work implement required horsepower and the transmission required horsepower and decreasing the ratio portions of the work implement required horsepower and the transmission required horsepower when the sum of the work implement required horsepower, the transmission required horsepower and the energy management required horsepower is greater than a predetermined load upper limit horsepower; and

the distribution ratio determination unit prioritizing the energy management required horsepower over the priority portions of the work implement required horsepower and the transmission required horsepower.

2. The work vehicle according to claim 1, wherein

the control unit further includes

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 that stores torque-balance information to define 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; 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.

3. The work vehicle according to claim 2, wherein

the transmission requirement determination unit determines 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 determines the target output torque on the basis of the required tractive force.

4. The work vehicle according to claim 3, 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 an operation amount of the accelerator operating member.

5. The work vehicle according to claim 4, wherein

the transmission requirement determination unit determines the required tractive force characteristics by multiplying 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 an operation amount of the accelerator operating member.

6. The work vehicle according to claim 5, 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 accelerator operating member.

7. The work vehicle according to claim 3, wherein

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

8. The work vehicle according to claim 2, wherein

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

9. The work vehicle according to claim 8, wherein

the engine requirement determination unit determines the 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 determines 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 defines a value smaller than the target output torque of the engine determined from the engine required horsepower and the engine rotation speed, as the upper limit of the target input torque.

10. The work vehicle according to claim 9, wherein

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

11. The work vehicle according to claim 10, 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.

12. The work vehicle according to claim 1, wherein

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 a torque that corresponds 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.

13. The work vehicle according to claim 12, wherein

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

14. The work vehicle according to claim 2, wherein

the power-transmission device further has a mode-switching mechanism for selectively switching a drive-power transmission path for the power-transmission device between a plurality of modes that 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.

15. 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 including a planetary gear mechanism, the gear mechanism being configured to transmit rotation of the input shaft to the output shaft, a motor connected to a rotating element of the planetary gear mechanism, and an energy reservoir unit for storing energy generated in the motor, 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 detecting an operation amount of a work implement operating member;

a step for detecting a hydraulic pressure of a hydraulic pump for driving the work implement;

a step for detecting a vehicle speed;

a step for detecting an operation amount of an accelerator operating member;

a step for determining a work implement required horsepower on the basis of an operation amount of the work implement operating member and the hydraulic pressure;

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

a step for determining an engine required horsepower on the basis of the work implement required horsepower and the transmission required horsepower;

a step for determining a required throttle value based on the engine required horsepower;

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

a step for dividing the work implement required horsepower and the transmission required horsepower into respective priority portions and respective ratio portions;

a step for prioritizing the energy management required horsepower over the priority portions of the work implement required horsepower and the transmission required horsepower;

a step for prioritizing the priority portions of the work implement required horsepower and the transmission required horsepower over the ratio portions of the work implement required horsepower and the transmission required horsepower; and

a step for maintaining the priority portions of the work implement required horsepower and the transmission required horsepower and decreasing the ratio portions of the work implement required horsepower and the transmission required horsepower when the sum of the work implement required horsepower, the transmission required horsepower and the energy management required horsepower is greater than a predetermined load upper limit horsepower.