# US 10,370,823 B2 · Work vehicle and method of controlling work vehicle

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- Number: US 10,370,823 B2
- Document ID: US10370823B2
- Status: Granted
- Kind: B2
- Application number: 15/026,675
- Filed: 2014-12-17
- Published: 2016-08-18
- Granted: 2019-08-06
- Earliest claimed: 2014-01-31
- Assignees: Komatsu Ltd.
- Applicants: Komatsu Ltd.
- Inventors: Shunsuke Miyamoto; Masao Yoshizawa; Yasuo Fujiwara
- Web page: https://patentgrep.com/patent/US10370823B2

## CPC

- E02F 9/2079: {Control of mechanical transmission (for hydrostatic transmission or hydraulic torque converter E02F9/2253)}
- B60K 6/387: Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
- B60K 6/445: Differential gearing distribution type
- B60W 10/06: including control of combustion engines
- B60W 10/08: including control of electric propulsion units, e.g. motors or generators
- B60W 10/10: including control of change-speed gearings
- 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)}
- E02F 9/2004: {Control mechanisms, e.g. control levers (control levers per se G05G)}
- E02F 9/202: {Mechanical transmission, e.g. clutches, gears (clutches per se F16D, gears per se F16H)}
- E02F 9/2075: {of the hybrid type (for vehicles in general B60W20/00)}
- F16H 3/44: using gears having orbital motion
- F16H 3/728: {with means to change ratio in the mechanical gearing}
- F16H 59/18: dependent on the position of the accelerator pedal
- B60K 6/365: with the gears having orbital motion
- B60K 2006/381: {characterized by driveline brakes}
- B60W 20/00: Control systems specially adapted for hybrid vehicles {(hybrid vehicle design, B60K6/00; electric vehicles B60L)}
- B60W 2300/17: Construction vehicles, e.g. graders, excavators
- B60W 2510/0638: Engine speed
- B60W 2520/10: Longitudinal speed
- B60W 2710/0644: Engine speed
- B60Y 2200/415: Wheel loaders
- B60Y 2300/70: Control of gearings
- B60Y 2400/73: Planetary gearings
- E02F 3/283: {with a single arm pivoted directly on the chassis (linkage mechanism for it E02F3/3405)}
- E02F 9/2066: {of the type combustion engines}
- E02F 9/2292: {Systems with two or more pumps}
- E02F 9/2296: {Systems with a variable displacement pump}
- F16H 2037/101: {Power-split transmissions with one differential at each end of a continuously variable transmission, i.e. CVT}
- F16H 2061/6601: {with arrangements for dividing torque and shifting between different ranges}
- F16H 2061/6602: {with at least two dynamo-electric machines for creating an electric power path inside the transmission device, e.g. using generator and motor for a variable power torque path}
- F16H 2200/2007: with two sets of orbital gears
- F16H 2200/2041: with four engaging means
- Y02T 10/62: Hybrid vehicles
- Y10S 903/903: having energy storing means, e.g. battery, capacitor
- E02F: DREDGING; SOIL-SHIFTING (winning peat E21C49/00)
- B60K: ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
- B60W: CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- F16H: GEARING
- B60Y: INDEXING SCHEME RELATING TO ASPECTS CROSS-CUTTING VEHICLE TECHNOLOGY
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS

## Abstract

A power transmission device of a work vehicle includes a mode switching mechanism configured to switch a drive power transmission route to one mode of at least two modes. A second mode is used in a range with the higher transmission speed ratio than a first mode. A controller increases the rotation speed of the engine from a first rotation speed for the engine corresponding to a first vehicle speed when the vehicle speed is within a range greater than the first vehicle speed where the transmission speed ratio reaches a predetermined first value that is less than the maximum value of the transmission speed ratio obtainable by the power transmission device. When the transmission route is in the second mode, the first value is greater than a second value of the transmission speed ratio at which the rotation speeds of the first motor and the second motor are equal.

## Claims

### Claim 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 apparatus driven by the engine;
a power transmission device that transmits drive power from the engine to the travel apparatus;
a controller that controls 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 transmitting rotation of the input shaft to the output shaft,
a first motor and a second motor each connected to rotational elements in the planetary gear mechanism, and
a mode switching mechanism that switches a drive power transmission route in the power transmission device to one mode of at least two modes,
the gear mechanism being configured such that varying rotation speeds of the motors varies a transmission speed ratio in the power transmission device, the transmission speed ratio being a ratio of a rotation speed of the output shaft to a rotation speed of the input shaft,
the at least two modes including a first mode and a second mode, the second mode being used in a range of the transmission speed ratio that is higher than a range of the transmission speed ratio in which the first mode is used,
the controller being configured such that when a vehicle speed of the work vehicle increases beyond a first vehicle speed where the transmission speed ratio reaches a predetermined first value that is less than a maximum value of the transmission speed ratio obtainable by the power transmission device, the controller increases a rotation speed of the engine from a first engine rotation speed corresponding to the first vehicle speed, and
the first value of the transmission speed ratio being greater than a second value of the transmission speed ratio, the second value being a value of the transmission speed ratio at which the rotation speed of the first motor and the rotation speed of the second motor are equal when the transmission route is in the second mode.

### Claim 2 (depends on 1)

The work vehicle according to claim 1, wherein
the range of transmission speed ratios used during the second mode is the range with the highest of the transmission speed ratios among the ranges that can be used during the at least two modes.

### Claim 3 (depends on 2)

The work vehicle according to claim 2, wherein
when the transmission speed ratio is at a predetermined mode switching threshold, a rotation speed ratio of the first motor to the input shaft is the same in the first mode of the drive power transmission route as in the second mode of the drive power transmission route, and a rotation speed ratio of the second motor to the input shaft is the same in the first mode of the drive power transmission route as in the second mode of the drive power transmission route; and
the second value of the transmission speed ratio is greater than the mode switching threshold and less than the maximum value of the transmission speed ratio.

### Claim 4 (depends on 1)

The work vehicle according to claim 1, wherein
the controller increases the rotation speed of the engine linearly in relation to the vehicle speed when the controller increases the engine speed from the first engine rotation speed in response to the vehicle speed being in a range of the vehicle speeds greater than the first vehicle speed.

### Claim 5 (depends on 1)

The work vehicle according to claim 1, wherein
the controller further includes a motor control unit that controls the first motor and the second motor to hold the transmission speed ratio at the first value while the rotation speed of the engine is increasing.

### Claim 6 (depends on 5)

The work vehicle according to claim 5, wherein
the motor control unit controls the rotation speed of at least one of the first motor and the second motor to be proportional to the rotation speed of the engine.

### Claim 7 (depends on 5)

The work vehicle according to claim 5, further comprising
an accelerator operating member configured to be operated by an operator
the controller including an engine control unit configured to increase a torque output from the engine as an operation amount of the accelerator operating member increases, and decrease the torque output from the engine as the operation amount of the accelerator operating member decreases when the vehicle speed increases beyond the first vehicle speed.

### Claim 8 (depends on 5)

The work vehicle according to claim 5, wherein
the motor control unit releases the hold on the transmission speed ratio when the rotation speed of the engine reaches or falls below a predetermined second engine rotation speed while the transmission speed ratio is being held at the first value.

### Claim 9 (depends on 5)

The work vehicle according to claim 5, further comprising
a work implement operating member configured to be used by an operator to operate the work implement;
the motor control unit releasing the hold on the transmission speed ratio when the work implement operating member is operated.

### Claim 10 (depends on 1)

The work vehicle according to claim 1, wherein
the first motor and the second motor are electric motors.

### Claim 11

A method of controlling a work vehicle provided with a power transmission device,
the power transmission device including
an input shaft,
an output shaft,
a gear mechanism including a planetary gear mechanism that transmits a rotation of the input shaft to the output shaft,
a first motor and a second motor each connected to rotational elements in the planetary gear mechanism, and
a mode switching mechanism that switches a drive power transmission route in the power transmission device to one mode of at least two modes,
the gear mechanism being configured such that varying the rotation speed of the motors varies the transmission speed ratio, the transmission speed ratio being a ratio of a rotation speed of the output shaft to a rotation speed of the input shaft,
the at least two modes including a first mode and a second mode, the second mode used in a range of the transmission speed ratio that is higher than a range of the transmission speed ratio in which the first mode is used, and
the method comprising:
increasing a rotation speed of the engine from a first engine rotation speed corresponding to a first vehicle speed when a vehicle speed of the work vehicle is in a range greater than the first vehicle speed, the first vehicle speed being a vehicle speed where the transmission speed ratio is a predetermined first value that is less than a maximum value of the transmission speed ratio obtainable by the power transmission device,
the first value being greater than a second value of the transmission speed ratio, the second value being a value of the transmission speed ratio at which the rotation speed of the first motor and the rotation speed of the second motor are equal when the transmission route is in the second mode.