WO2024116544A1 - Work machine and method for controlling work machine - Google Patents

Work machine and method for controlling work machine Download PDF

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Publication number
WO2024116544A1
WO2024116544A1 PCT/JP2023/033259 JP2023033259W WO2024116544A1 WO 2024116544 A1 WO2024116544 A1 WO 2024116544A1 JP 2023033259 W JP2023033259 W JP 2023033259W WO 2024116544 A1 WO2024116544 A1 WO 2024116544A1
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WO
WIPO (PCT)
Prior art keywords
braking force
transmission
work machine
state
controller
Prior art date
Application number
PCT/JP2023/033259
Other languages
French (fr)
Japanese (ja)
Inventor
陽 竹野
Original Assignee
株式会社小松製作所
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Filing date
Publication date
Application filed by 株式会社小松製作所 filed Critical 株式会社小松製作所
Publication of WO2024116544A1 publication Critical patent/WO2024116544A1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T7/00—Brake-action initiating means
    • B60T7/12—Brake-action initiating means for automatic initiation; for initiation not subject to will of driver or passenger
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
    • B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
    • B60T8/32—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration
    • B60T8/34—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition
    • B60T8/48—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force responsive to a speed condition, e.g. acceleration or deceleration having a fluid pressure regulator responsive to a speed condition connecting the brake actuator to an alternative or additional source of fluid pressure, e.g. traction control systems
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16D—COUPLINGS FOR TRANSMITTING ROTATION; CLUTCHES; BRAKES
    • F16D48/00—External control of clutches
    • F16D48/06—Control by electric or electronic means, e.g. of fluid pressure
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H61/00—Control functions within control units of change-speed- or reversing-gearings for conveying rotary motion ; Control of exclusively fluid gearing, friction gearing, gearings with endless flexible members or other particular types of gearing
    • F16H61/38—Control of exclusively fluid gearing
    • F16H61/40—Control of exclusively fluid gearing hydrostatic

Definitions

  • the present invention relates to a work machine and a method for controlling the work machine.
  • Some work machines are equipped with a transmission. When the operator is not operating the accelerator pedal, a braking force is applied to the work machine by the inertial braking force from the transmission.
  • the work machine of Patent Document 1 is equipped with an HST (Hydrostatic Transmission).
  • the HST is equipped with a hydraulic pump and a hydraulic motor.
  • an inertial braking force is generated by the internal load of the hydraulic pump, hydraulic motor, and engine. The operator uses this inertial braking force to adjust the vehicle speed of the work machine.
  • the inertial braking force from the transmission there is a limit to the inertial braking force from the transmission. Therefore, for example, when going downhill, the inertial braking force from the transmission may be insufficient to provide the required braking force. Furthermore, the inertial braking force may change depending on the state of the transmission. For this reason, it is difficult to stably adjust the vehicle speed of a work machine using the inertial braking force.
  • the object of this disclosure is to obtain a stable braking force in a work machine, regardless of a shortage or fluctuation of the inertial braking force.
  • a work machine includes a drive source, a transmission, a traveling device, a brake device, and a controller.
  • the transmission is connected to the drive source.
  • the traveling device is connected to the transmission and drives the work machine.
  • the brake device brakes the traveling device.
  • the controller obtains a braking command for braking the work machine.
  • the controller determines a target braking force during inertial traveling of the work machine based on the braking command.
  • the controller determines an auxiliary braking force so that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device.
  • the controller determines whether the transmission is in an over-revving state. If the controller determines that the transmission is in an over-revving state, the controller increases the auxiliary braking force.
  • a method according to another aspect of the present disclosure is a method for controlling a work machine.
  • the work machine includes a drive source, a transmission, a traveling device, and a brake device.
  • the transmission is connected to the drive source.
  • the traveling device is connected to the transmission and drives the work machine.
  • the brake device brakes the traveling device.
  • the method includes obtaining a braking command for braking the work machine, determining a target braking force during inertial traveling of the work machine based on the braking command, determining an auxiliary braking force such that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device, determining whether the transmission is in an over-revving state, and increasing the auxiliary braking force when it is determined that the transmission is in an over-revving state.
  • the auxiliary braking force is determined so that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device. Therefore, when the inertial braking force is insufficient for the target braking force, the shortage is made up by the braking force from the brake device. Furthermore, even if the inertial braking force fluctuates, a stable braking force is obtained by determining the target braking force. As a result, in the work machine, a stable braking force is obtained regardless of a shortage or fluctuation of the inertial braking force. Furthermore, when it is determined that the transmission is in an over-revving state, the auxiliary braking force is increased. As a result, when going downhill, for example, if the target braking force set by the braking command is insufficient to meet the required braking force, the auxiliary braking force is increased to decelerate the work machine.
  • FIG. 1 is a side view of a work machine according to an embodiment.
  • FIG. 2 is a block diagram showing the configuration of a work machine.
  • FIG. 4 is a diagram showing an example of driving force characteristics of a work machine.
  • FIG. 2 is a diagram showing a configuration of a hydraulic circuit for driving a brake device.
  • 4 is a flowchart showing a process of automatic brake control.
  • FIG. 11 is a diagram showing an example of a first level target braking force.
  • FIG. 11 is a diagram showing an example of a second level target braking force.
  • FIG. 13 is a diagram showing an example of a third level target braking force.
  • FIG. 4 is a diagram showing an example of a braking force when the transmission is in an overspeed state.
  • 10 is a flowchart showing a process of automatic brake control according to a modified example.
  • 13 is a diagram showing an example of a braking force when the transmission is in an overspeed state in automatic brake control according to a modified
  • Fig. 1 is a side view of a work machine 1 according to an embodiment.
  • Fig. 2 is a block diagram showing the configuration of the work machine 1.
  • the work machine 1 is a wheel loader.
  • the work machine 1 includes a vehicle body 2 and a work implement 3.
  • the vehicle body 2 includes a front vehicle body 2a and a rear vehicle body 2b.
  • the rear vehicle body 2b is connected to the front vehicle body 2a so that it can turn left and right.
  • a hydraulic cylinder 15 is connected to the front vehicle body 2a and the rear vehicle body 2b. The hydraulic cylinder 15 extends and retracts, causing the front vehicle body 2a to turn left and right relative to the rear vehicle body 2b.
  • the work machine 3 is used for work such as excavation.
  • the work machine 3 is attached to the front body 2a so as to be operable.
  • the work machine 3 includes a boom 11, a bucket 12, and hydraulic cylinders 13 and 14.
  • the boom 11 and the bucket 12 operate as the hydraulic cylinders 13 and 14 extend and retract.
  • the work machine 1 includes a drive source 21, a transmission 24, and a traveling device 25.
  • the drive source 21 is, for example, a diesel engine.
  • the drive source 21 is provided with a fuel injection device 30.
  • the fuel injection device 30 controls the output of the drive source 21 by adjusting the amount of fuel injected into the cylinder of the drive source 21.
  • the transmission 24 is connected to the drive source 21.
  • the transmission 24 transmits the drive force from the drive source 21 to the traveling device 25.
  • the transmission 24 is an HST and includes a hydraulic pump 38 and a hydraulic motor 39.
  • the transmission 24 can continuously change the gear ratio by controlling the capacity of each of the hydraulic pump 38 and the hydraulic motor 39.
  • the transmission 24 includes a clutch 40.
  • the clutch 40 can be switched between an engaged state and a disengaged state.
  • the transmission 24 transmits the drive force to the traveling device 25 when the clutch 40 is engaged.
  • the transmission 24 cuts off the drive force to the traveling device 25 when the clutch 40 is disengaged.
  • the transmission 24 may be another type of transmission, such as an Electric Mechanical Transmission (EMT) or a Hydraulic Mechanical Transmission (HMT).
  • EMT Electric Mechanical Transmission
  • HMT Hydraulic Mechanical Transmission
  • the transmission 24 may be a transmission that includes a torque converter and multiple shift gears.
  • the running device 25 is mounted on the vehicle body 2 and is driven by the driving force from the drive source 21 to cause the vehicle body 2 to run.
  • the running device 25 includes axles 26, 27, front wheels 28A, 28B, and rear wheels 28C, 28D.
  • the axles 26, 27 are connected to the transmission 24.
  • the front wheels 28A, 28B are provided on the front vehicle body 2a.
  • the rear wheels 28C, 28D are provided on the rear vehicle body 2b.
  • the axle 26 transmits the driving force from the transmission 24 to the front wheels 28A, 28B.
  • the axle 27 transmits the driving force from the transmission 24 to the rear wheels 28C, 28D.
  • the work machine 1 includes a PTO (Power Take Off) 31, a work implement pump 32, and a control valve 33.
  • the PTO 31 distributes the driving force of the drive source 21 to the transmission 24 and the work implement pump 32. Note that only one work implement pump 32 is illustrated in FIG. 2. However, two or more hydraulic pumps may be connected to the drive source 21 via the PTO 31.
  • the work implement pump 32 is connected to the drive source 21 via the PTO 31.
  • the work implement pump 32 is a hydraulic pump.
  • the work implement pump 32 is driven by the drive source 21 and discharges hydraulic oil.
  • the hydraulic oil discharged from the work implement pump 32 is supplied to the hydraulic cylinders 13-15 described above.
  • the control valve 33 controls the flow rate of the hydraulic oil supplied from the work implement pump 32 to the hydraulic cylinders 13-15.
  • the control valve 33 is, for example, an electromagnetic proportional control valve, and is controlled in response to an input electrical signal.
  • the control valve 33 may be a pressure proportional control valve, and is controlled in response to an input pilot pressure.
  • the work machine 1 includes a brake pump 36 and braking devices 37A-37D.
  • the braking devices 37A-37D are hydraulic brakes.
  • the brake pump 36 is driven by the drive source 21 and discharges hydraulic oil.
  • the hydraulic oil discharged from the brake pump 36 is supplied to the braking devices 37A-37D.
  • the braking devices 37A-37D are driven by the hydraulic oil to brake the traveling device 25.
  • the braking devices 37A-37D are, for example, wet-type multi-plate brakes.
  • the braking devices 37A-37D include front brakes 37A, 37B and rear brakes 37C, 37D.
  • the front brakes 37A, 37B brake the front wheels 28A, 28B.
  • the rear brakes 37C, 37D brake the rear wheels 28C, 28D.
  • the work machine 1 includes an engine sensor 34 and a vehicle speed sensor 35.
  • the engine sensor 34 detects the engine rotation speed.
  • the vehicle speed sensor 35 detects the vehicle speed.
  • the vehicle speed sensor 35 detects, for example, the output rotation speed of the traveling device 25 as the vehicle speed.
  • the output rotation speed of the traveling device 25 corresponds to the vehicle speed of the work machine 1.
  • the output rotation speed of the traveling device 25 is, for example, the rotation speed of the output shaft of the transmission 24. However, the output rotation speed may also be the rotation speed of another rotating element located within the transmission 24 or downstream of the transmission 24.
  • the work machine 1 includes a controller 41.
  • the controller 41 includes a processor such as a CPU (central processing unit) and storage devices such as RAM and ROM.
  • the controller 41 may include an auxiliary storage device such as a hard disk or an SSD (Solid State Drive).
  • the controller 41 stores programs and data for controlling the work machine 1.
  • the controller 41 executes processing for controlling the work machine 1 in accordance with the stored programs and data.
  • the controller 41 receives a signal indicating the engine rotation speed from the engine sensor 34.
  • the controller 41 receives a signal indicating the output rotation speed from the vehicle speed sensor 35.
  • the controller 41 controls the output of the drive source 21 by sending a command signal to the drive source 21.
  • the controller 41 switches the transmission 24 between a forward gear and a reverse gear by sending a command signal to the transmission 24.
  • the controller 41 controls the gear ratio of the transmission 24 by sending a command signal to the transmission 24.
  • the controller 41 switches the clutch 40 between an engaged state and a disengaged state by sending a command signal to the transmission 24.
  • the controller 41 controls the work implement 3 by sending a command signal to the work implement pump 32 and the control valve 33.
  • the work machine 1 includes an FR operating member 42, an accelerator operating member 43, a work equipment operating member 44, a brake operating member 45, and a setting device 46.
  • the FR operating member 42 can be operated by an operator to switch the work machine 1 between forward and reverse.
  • the FR operating member 42 can be operated from a neutral position to a forward position and a reverse position.
  • the FR operating member 42 is, for example, a lever.
  • the FR operating member 42 may also be another member such as a switch or a pedal.
  • the accelerator operating member 43 can be operated by an operator to control the vehicle speed of the work machine 1.
  • the accelerator operating member 43 is, for example, a pedal.
  • the accelerator operating member 43 may be another member such as a lever or a switch.
  • the work machine operating member 44 can be operated by an operator to control the work machine 3.
  • the work machine operating member 44 is, for example, a lever.
  • the work machine operating member 44 may be another member such as a switch or a pedal.
  • the controller 41 receives a signal indicating the operating position of the FR operating member 42 from the FR operating member 42.
  • the controller 41 switches between the forward gear and the reverse gear of the transmission 24 in response to the signal from the FR operating member 42.
  • the controller 41 receives a signal indicating the accelerator operation amount from the accelerator operating member 43.
  • the accelerator operation amount is the operation amount of the accelerator operating member 43.
  • Figure 3 is a diagram showing the driving force characteristics of the work machine 1.
  • the solid line F1 shows the driving force characteristics when the accelerator operation amount is 100%.
  • the dashed line F2 shows the driving force characteristics when the accelerator operation amount is 0%.
  • the controller 41 controls the driving source 21 and the transmission 24 according to the accelerator operation amount and the vehicle speed so as to obtain the driving force characteristics shown in Figure 3.
  • the driving force includes positive and negative values.
  • a positive driving force indicates a positive driving force that drives the work machine 1.
  • a negative driving force indicates a negative driving force that brakes the work machine 1, i.e., an inertial braking force from the transmission 24.
  • the inertial braking force is what is known as an engine brake, and is a braking force due to the internal load of the transmission 24 and the drive source 21.
  • the brake operating member 45 can be operated by an operator to drive the brake devices 37A-37D.
  • the brake operating member 45 is, for example, a pedal.
  • the brake operating member 45 may be another member such as a lever or a switch.
  • the hydraulic pressure of the hydraulic oil supplied to the brake devices 37A-37D is controlled in response to the operation of the brake operating member 45.
  • the brake devices 37A-37D generate a braking force in response to the amount of operation of the brake operating member 45.
  • FIG. 4 is a diagram showing a hydraulic circuit 50 for driving the brake devices 37A-37D.
  • the hydraulic circuit 50 includes a flow dividing valve 51, a first flow path 52, a second flow path 53, a third flow path 54, an automatic brake valve 55, a manual brake valve 56, and a shuttle valve 57.
  • the flow dividing valve 51 divides the hydraulic oil from the brake pump 36 described above into the second flow path 53 and the third flow path 54.
  • the first flow path 52 is connected to the second flow path 53.
  • the automatic brake valve 55 is electrically connected to the controller 41.
  • the automatic brake valve 55 is, for example, a solenoid valve, and is electrically controlled in response to a command signal from the controller 41.
  • the automatic brake valve 55 changes the hydraulic pressure (hereinafter referred to as the first hydraulic pressure) supplied from the automatic brake valve 55 to the brake devices 37A-37D via the first flow path 52.
  • the manual brake valve 56 is connected to the brake operating member 45.
  • the manual brake valve 56 is mechanically connected to the brake operating member 45 via a link member such as a spring.
  • the manual brake valve 56 is connected to the second flow path 53 and the third flow path 54.
  • the manual brake valve 56 changes the hydraulic pressure (hereinafter referred to as the second hydraulic pressure) supplied from the manual brake valve 56 to the brake devices 37A-37D via the second flow path 53 and the third flow path 54 according to the amount of operation of the brake operating member 45.
  • the shuttle valve 57 is connected to the first flow path 52, the second flow path 53, and the third flow path 54.
  • the shuttle valve 57 selectively supplies the first hydraulic pressure from the automatic brake valve 55 and the second hydraulic pressure from the manual brake valve 56 to the brake devices 37A-37D.
  • the shuttle valve 57 supplies the larger of the first hydraulic pressure and the second hydraulic pressure to the brake devices 37A-37D. Therefore, for example, when the first hydraulic pressure due to the operation of the brake operating member 45 by the operator is larger than the second hydraulic pressure due to the command signal from the controller 41, the first hydraulic pressure is supplied to the brake devices 37A-37D. Thereby, the braking force of the brake devices 37A-37D is controlled according to the amount of operation of the brake operating member 45 by the operator.
  • the second hydraulic pressure based on the command signal from the controller 41 is greater than the first hydraulic pressure based on the operator's operation of the brake operating member 45, the second hydraulic pressure is supplied to the brake devices 37A-37D. This controls the braking force of the brake devices 37A-37D in response to the command signal from the controller 41.
  • the controller 41 executes automatic brake control that automatically controls the braking force when the work machine 1 is running by inertia.
  • the inertial running of the work machine 1 means a state in which the work machine 1 is running by inertia with the accelerator operating member 43 and the brake operating member 45 not being operated.
  • the setting device 46 can be operated by an operator to set the target braking force during inertial running in the automatic brake control.
  • the setting device 46 is, for example, a dial switch. However, the setting device may be other devices such as a slide switch, a push button switch, or a touch panel.
  • the setting device 46 outputs a braking command indicating the target braking force in response to operation by the operator.
  • the target braking force is indicated in a plurality of levels.
  • the plurality of levels includes, for example, a first level, a second level, and a third level.
  • the first level has the largest target braking force.
  • the third level has the smallest target braking force.
  • the second level has a target braking force between the first and second levels.
  • FIG. 5 is a flowchart showing the process of automatic brake control. As shown in FIG. 5, in step S101, the controller 41 obtains a braking command. The controller 41 obtains a braking command indicating a target braking force set by the operator using the setting device 46.
  • step S102 the controller 41 determines a target braking force.
  • the controller 41 determines the target braking force based on a braking command from the setting device 46.
  • step S103 the controller 41 acquires transmission information.
  • the transmission information indicates the state of the transmission 24.
  • the transmission information includes, for example, the gear ratio of the transmission 24.
  • the transmission information includes the vehicle speed. If the transmission 24 is an HST, the transmission information may include the capacity of the hydraulic pump and the capacity of the hydraulic motor. If the transmission 24 includes multiple shift gears, the transmission information may include the gear ratio of the shift gears.
  • step S104 the controller 41 calculates the inertial braking force from the transmission 24.
  • the controller 41 calculates the inertial braking force from the transmission 24 based on the above-mentioned transmission information.
  • step S105 the controller 41 determines the auxiliary braking force.
  • the controller 41 determines the auxiliary braking force so that the target braking force is obtained by the inertial braking force from the transmission 24 and the auxiliary braking force from the brake devices 37A-37D.
  • the controller 41 determines the braking force equivalent to the difference between the target braking force and the inertial braking force as the auxiliary braking force.
  • step S106 the controller 41 controls the automatic brake valve 55.
  • the controller 41 calculates the target brake hydraulic pressure for the brake devices 37A-37D, which corresponds to the auxiliary braking force.
  • the controller 41 controls the opening of the automatic brake valve 55 so that the target brake hydraulic pressure is supplied to the brake devices 37A-37D.
  • step S107 the controller 41 determines whether the transmission 24 is in the first over-speed state.
  • the controller 41 determines that the transmission 24 is in the first over-speed state when the vehicle speed is equal to or greater than the first threshold value. If the controller 41 determines that the transmission 24 is in the first over-speed state, the process proceeds to step S108.
  • step S108 the controller 41 increases the auxiliary braking force. For example, the controller 41 increases the auxiliary braking force to the maximum braking force of the brake devices 37A-37D. Alternatively, the controller 41 may increase the auxiliary braking force in stages.
  • step S109 the controller 41 determines whether the transmission 24 is in a second over-speed state.
  • the controller 41 determines that the transmission 24 is in a second over-speed state when the vehicle speed is equal to or greater than a second threshold value.
  • the second threshold value is greater than the first threshold value. If the controller 41 determines that the transmission 24 is in a second over-speed state, the process proceeds to step S110.
  • step S110 the controller 41 switches the clutch 40 to a disengaged state. This blocks the transmission of driving force from the travel device 25 to the transmission 24.
  • the second threshold is determined from the perspective of protecting the transmission 24 from overspeed. The second threshold is determined based on, for example, the maximum allowable speed of the hydraulic motor, hydraulic pump, or engine of the transmission 24. The first threshold is smaller than the second threshold. The first threshold is determined from the perspective of preventing the transmission 24 from entering a second overspeed state.
  • L1 shows an example of a first level target braking force.
  • L2 shows an example of a second level target braking force.
  • L3 shows an example of a third level target braking force.
  • Data showing the relationship between the first to third level target braking forces L1-L3 and the vehicle speed is stored in the controller 41.
  • the controller 41 determines a target braking force L1 according to the vehicle speed.
  • L0 indicates the inertial braking force from the transmission 24 during inertial running.
  • the controller 41 calculates the inertial braking force L0 from the transmission information.
  • the controller 41 calculates the target brake oil pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference dF between the target braking force L1 and the inertial braking force L0.
  • the controller 41 controls the opening degree of the automatic brake valve 55 so that the target brake oil pressure is supplied to the brake devices 37A-37D.
  • the target braking force L2 of the second level is smaller than the target braking force L1 of the first level.
  • the controller 41 determines the target braking force L2 according to the vehicle speed. Thereafter, in the same manner as when the first level is set, the controller 41 calculates the target brake hydraulic pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference between the target braking force L2 and the inertial braking force L0, and controls the opening of the automatic brake valve 55 according to the target brake hydraulic pressure.
  • the target braking force L3 of the third level is smaller than the target braking force L2 of the second level.
  • the controller 41 determines the target braking force L3 according to the vehicle speed. Thereafter, in the same manner as when the first level is set, the controller 41 calculates the target brake hydraulic pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference between the target braking force L3 and the inertial braking force L0, and controls the opening of the automatic brake valve 55 according to the target brake hydraulic pressure.
  • the braking force during inertial running can be changed. Therefore, when the work machine 1 runs on the same downhill slope, the vehicle speed at which the work machine 1 is stabilized during inertial running can be changed. Furthermore, even on a downhill slope that cannot be stabilized by the inertial braking force from the transmission 24 alone, the work machine 1 can run at a constant vehicle speed. Note that “stabilized” refers to a state in which the work machine 1 runs at a constant speed during inertial running.
  • the static braking force that balances the force accelerating the work machine 1 (hereinafter referred to as the static braking force) is assumed to be A1. If the inertial braking force L0 from the transmission 24 is smaller than the static braking force A1, the work machine 1 cannot be stabilized by the inertial braking force from the transmission 24 alone.
  • the work machine 1 can travel at a constant speed at a vehicle speed V1 where the target braking force L1 is balanced with the static braking force A1.
  • the work machine 1 can travel at a constant speed at a vehicle speed V2 where the target braking force L2 is balanced with the static braking force A1.
  • a braking force equivalent to the target braking force L3 of level 3 can be obtained.
  • This allows the work machine 1 to travel at a constant speed at a vehicle speed V3 where the target braking force L3 is balanced with the static braking force A1.
  • the operator can change the vehicle speed at which the work machine 1 is statically determined during inertial traveling by changing the target braking force using the setting device 46.
  • the static braking force A2 may be greater than the target braking force L2 set by the operator. In this case, the work machine 1 cannot be stabilized at the target braking force L2, and the vehicle speed increases. If the vehicle speed continues to increase, the transmission 24 may over-rev, and the transmission 24 may be damaged.
  • the controller 41 increases the auxiliary braking force applied by the brake devices 37A-37D. This results in a braking force C1 greater than the static braking force A2, as shown in FIG. 9, and the work machine 1 decelerates. Furthermore, the first threshold value B1 for increasing the auxiliary braking force is smaller than the second threshold value B2 at which the clutch 40 is switched to a disengaged state. Therefore, by increasing the auxiliary braking force before the clutch 40 is disengaged, the work machine 1 can be decelerated. This prevents the work machine 1 from becoming unable to travel.
  • the braking force by the brake devices 37A-37D is controlled based on the difference between the target braking force and the inertial braking force. Therefore, when the inertial braking force is insufficient compared to the target braking force, the shortfall can be made up for by the braking force by the brake devices 37A-37D. Furthermore, even if the inertial braking force fluctuates, a stable braking force can be obtained by determining the target braking force. As a result, in the work machine 1, a stable braking force can be obtained regardless of a shortage or fluctuation of the inertial braking force.
  • the auxiliary braking force is increased.
  • the target braking force set by the braking command is insufficient to provide the necessary braking force
  • the auxiliary braking force is increased, and the work machine 1 is decelerated.
  • the work machine 1 is not limited to a wheel loader, but may be other machines such as a bulldozer or a motor grader.
  • the work machine 1 may be operable remotely.
  • the FR operation member 42, the accelerator operation member 43, the work machine operation member 44, the brake operation member 45, and the setting device 46 may be disposed outside the work machine 1.
  • the driving source 21 is not limited to an engine, and may include an electric motor.
  • the controller 41 may be composed of multiple controllers. The above-mentioned control processing of the work machine 1 may be distributed and executed by multiple controllers.
  • the automatic brake control process is not limited to that of the above-described embodiment, and may be modified.
  • the number of levels of the target braking force is not limited to three.
  • the number of levels of the target braking force may be more than three, or less than three.
  • the target braking force may be indicated by a numerical value of the braking force.
  • FIG. 10 is a flowchart showing the process of automatic brake control according to the modified example.
  • steps S201 to S206 are similar to steps S101 to S106 in the above-described embodiment.
  • step S207 the controller 41 determines whether the transmission 24 is in an overspeed state. The controller 41 determines that the transmission 24 is in an overspeed state when the vehicle speed is equal to or greater than the above-described second threshold value B2. If the controller 41 determines that the transmission 24 is in an overspeed state, the process proceeds to step S208.
  • step S208 the controller 41 switches the clutch 40 to a disengaged state.
  • step S209 the controller 41 increases the auxiliary braking force. That is, as shown in FIG. 11, the controller 41 increases the auxiliary braking force when the vehicle speed is equal to or greater than the second threshold value B2 at which the clutch 40 is switched to a disengaged state. This makes it possible to decelerate the work machine 1 by the braking force C2 applied by the brake devices 37A-37D with the transmission of driving force from the transmission 24 to the traveling device 25 cut off.
  • a stable braking force can be obtained in a work machine regardless of a lack of or fluctuation in the inertial braking force.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Transportation (AREA)
  • Regulating Braking Force (AREA)
  • Hydraulic Clutches, Magnetic Clutches, Fluid Clutches, And Fluid Joints (AREA)
  • Control Of Fluid Gearings (AREA)

Abstract

This work machine comprises: a drive source, a transmission, a traveling device, a brake device, and a controller. The transmission is connected to the drive source. The traveling device is connected to the transmission and causes the work machine to travel. The brake device brakes the traveling device. The controller acquires a braking command for braking the work machine. The controller determines a target braking force when the work machine is running on inertia on the basis of the braking command. The controller determines the auxiliary braking force such that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device. The controller determines whether the transmission is in an overspeed state. When the controller determines that the transmission is in the overspeed state, the controller increases the auxiliary braking force.

Description

作業機械、及び、作業機械を制御するための方法Work machine and method for controlling a work machine
　本発明は、作業機械、及び、作業機械を制御するための方法に関する。 The present invention relates to a work machine and a method for controlling the work machine.
　作業機械には、トランスミッションを備えるものがある。オペレータがアクセルペダルを操作していない場合には、トランスミッションからの慣性制動力によって、作業機械に制動力が作用する。例えば、特許文献１の作業機械は、ＨＳＴ（Hydro Static Transmission）を備えている。ＨＳＴは、油圧ポンプと油圧モータとを備えている。ＨＳＴでは、油圧ポンプと油圧モータとエンジンとの内部負荷により、慣性制動力が発生する。オペレータは、このような慣性制動力を利用することで、作業機械の車速を調整する。 Some work machines are equipped with a transmission. When the operator is not operating the accelerator pedal, a braking force is applied to the work machine by the inertial braking force from the transmission. For example, the work machine of Patent Document 1 is equipped with an HST (Hydrostatic Transmission). The HST is equipped with a hydraulic pump and a hydraulic motor. In the HST, an inertial braking force is generated by the internal load of the hydraulic pump, hydraulic motor, and engine. The operator uses this inertial braking force to adjust the vehicle speed of the work machine.
国際公開第２０２１／０６６０１９号International Publication No. 2021/066019
　しかし、トランスミッションからの慣性制動力には限界がある。そのため、例えば降坂時などに、トランスミッションからの慣性制動力では、必要な制動力に対して不足する場合がある。また、トランスミッションの状態に応じて、慣性制動力が変化する場合もある。そのため、慣性制動力によって作業機械の車速を安定して調整することは困難である。本開示の目的は、作業機械において、慣性制動力の不足、或いは変動に関わらず、安定した制動力を得ることにある。 However, there is a limit to the inertial braking force from the transmission. Therefore, for example, when going downhill, the inertial braking force from the transmission may be insufficient to provide the required braking force. Furthermore, the inertial braking force may change depending on the state of the transmission. For this reason, it is difficult to stably adjust the vehicle speed of a work machine using the inertial braking force. The object of this disclosure is to obtain a stable braking force in a work machine, regardless of a shortage or fluctuation of the inertial braking force.
　本開示の一態様に係る作業機械は、駆動源と、トランスミッションと、走行装置と、ブレーキ装置と、コントローラとを備える。トランスミッションは、駆動源に接続される。走行装置は、トランスミッションに接続され、作業機械を走行させる。ブレーキ装置は、走行装置を制動する。コントローラは、作業機械を制動するための制動指令を取得する。コントローラは、制動指令に基づいて作業機械の慣性走行時における目標制動力を決定する。コントローラは、トランスミッションからの慣性制動力と、ブレーキ装置による補助制動力とによって目標制動力が得られるように、補助制動力を決定する。コントローラは、トランスミッションが過回転状態であるかを判定する。コントローラは、トランスミッションが過回転状態であると判定した場合には、補助制動力を増大させる。 A work machine according to one embodiment of the present disclosure includes a drive source, a transmission, a traveling device, a brake device, and a controller. The transmission is connected to the drive source. The traveling device is connected to the transmission and drives the work machine. The brake device brakes the traveling device. The controller obtains a braking command for braking the work machine. The controller determines a target braking force during inertial traveling of the work machine based on the braking command. The controller determines an auxiliary braking force so that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device. The controller determines whether the transmission is in an over-revving state. If the controller determines that the transmission is in an over-revving state, the controller increases the auxiliary braking force.
　本開示の他の態様に係る方法は、作業機械を制御するための方法である。作業機械は、駆動源と、トランスミッションと、走行装置と、ブレーキ装置とを備える。トランスミッションは、駆動源に接続される。走行装置は、トランスミッションに接続され、作業機械を走行させる。ブレーキ装置は、走行装置を制動する。当該方法は、作業機械を制動するための制動指令を取得することと、制動指令に基づいて作業機械の慣性走行時における目標制動力を決定することと、トランスミッションからの慣性制動力と、ブレーキ装置による補助制動力とによって目標制動力が得られるように、補助制動力を決定することと、トランスミッションが過回転状態であるかを判定することと、トランスミッションが過回転状態であると判定した場合には、補助制動力を増大させること、を備える。 A method according to another aspect of the present disclosure is a method for controlling a work machine. The work machine includes a drive source, a transmission, a traveling device, and a brake device. The transmission is connected to the drive source. The traveling device is connected to the transmission and drives the work machine. The brake device brakes the traveling device. The method includes obtaining a braking command for braking the work machine, determining a target braking force during inertial traveling of the work machine based on the braking command, determining an auxiliary braking force such that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device, determining whether the transmission is in an over-revving state, and increasing the auxiliary braking force when it is determined that the transmission is in an over-revving state.
　本開示によれば、トランスミッションからの慣性制動力と、ブレーキ装置による補助制動力とによって目標制動力が得られるように、補助制動力決定される。そのため、慣性制動力が目標制動力に対して不足する場合に、ブレーキ装置による制動力によって、不足分が補われる。また、慣性制動力が変動しても、目標制動力が決定されることで、安定した制動力が得られる。それにより、作業機械において、慣性制動力の不足、或いは変動に関わらず、安定した制動力が得られる。また、トランスミッションが過回転状態であると判定された場合には、補助制動力が増大される。それにより、例えば降坂時において、制動指令によって設定された目標制動力では、必要な制動力に不足する場合には、補助制動力が増大されることで、作業機械が減速される。 According to the present disclosure, the auxiliary braking force is determined so that the target braking force is obtained by the inertial braking force from the transmission and the auxiliary braking force from the brake device. Therefore, when the inertial braking force is insufficient for the target braking force, the shortage is made up by the braking force from the brake device. Furthermore, even if the inertial braking force fluctuates, a stable braking force is obtained by determining the target braking force. As a result, in the work machine, a stable braking force is obtained regardless of a shortage or fluctuation of the inertial braking force. Furthermore, when it is determined that the transmission is in an over-revving state, the auxiliary braking force is increased. As a result, when going downhill, for example, if the target braking force set by the braking command is insufficient to meet the required braking force, the auxiliary braking force is increased to decelerate the work machine.
実施形態に係る作業機械の側面図である。FIG. 1 is a side view of a work machine according to an embodiment. 作業機械の構成を示すブロック図である。FIG. 2 is a block diagram showing the configuration of a work machine. 作業機械の駆動力特性の一例を示す図である。FIG. 4 is a diagram showing an example of driving force characteristics of a work machine. ブレーキ装置を駆動するための油圧回路の構成を示す図である。FIG. 2 is a diagram showing a configuration of a hydraulic circuit for driving a brake device. 自動ブレーキ制御の処理を示すフローチャートである。4 is a flowchart showing a process of automatic brake control. 第１レベルの目標制動力の一例を示す図である。FIG. 11 is a diagram showing an example of a first level target braking force. 第２レベルの目標制動力の一例を示す図である。FIG. 11 is a diagram showing an example of a second level target braking force. 第３レベルの目標制動力の一例を示す図である。FIG. 13 is a diagram showing an example of a third level target braking force. トランスミッションが過回転状態での制動力の一例を示す図である。FIG. 4 is a diagram showing an example of a braking force when the transmission is in an overspeed state. 変形例に係る自動ブレーキ制御の処理を示すフローチャートである。10 is a flowchart showing a process of automatic brake control according to a modified example. 変形例に係る自動ブレーキ制御でのトランスミッションが過回転状態での制動力の一例を示す図である。13 is a diagram showing an example of a braking force when the transmission is in an overspeed state in automatic brake control according to a modified example. FIG.
　以下、図面を参照して、本開示の一実施形態について説明する。図１は、実施形態に係る作業機械１の側面図である。図２は、作業機械１の構成を示すブロック図である。本実施形態において、作業機械１は、ホイールローダである。図１に示すように、作業機械１は、車体２と作業機３とを備えている。 Below, an embodiment of the present disclosure will be described with reference to the drawings. Fig. 1 is a side view of a work machine 1 according to an embodiment. Fig. 2 is a block diagram showing the configuration of the work machine 1. In this embodiment, the work machine 1 is a wheel loader. As shown in Fig. 1, the work machine 1 includes a vehicle body 2 and a work implement 3.
　車体２は、前車体２ａと後車体２ｂとを含む。後車体２ｂは、前車体２ａに対して左右に旋回可能に接続されている。前車体２ａと後車体２ｂとには、油圧シリンダ１５が連結されている。油圧シリンダ１５が伸縮することで、前車体２ａが、後車体２ｂに対して、左右に旋回する。 The vehicle body 2 includes a front vehicle body 2a and a rear vehicle body 2b. The rear vehicle body 2b is connected to the front vehicle body 2a so that it can turn left and right. A hydraulic cylinder 15 is connected to the front vehicle body 2a and the rear vehicle body 2b. The hydraulic cylinder 15 extends and retracts, causing the front vehicle body 2a to turn left and right relative to the rear vehicle body 2b.
　作業機３は、掘削等の作業に用いられる。作業機３は、前車体２ａに対して動作可能に、取り付けられている。作業機３は、ブーム１１と、バケット１２と、油圧シリンダ１３，１４とを含む。油圧シリンダ１３，１４が伸縮することによって、ブーム１１及びバケット１２が動作する。 The work machine 3 is used for work such as excavation. The work machine 3 is attached to the front body 2a so as to be operable. The work machine 3 includes a boom 11, a bucket 12, and hydraulic cylinders 13 and 14. The boom 11 and the bucket 12 operate as the hydraulic cylinders 13 and 14 extend and retract.
　図２に示すように、作業機械１は、駆動源２１と、トランスミッション２４と、走行装置２５とを含む。駆動源２１は、例えばディーゼルエンジンである。駆動源２１には、燃料噴射装置３０が設けられている。燃料噴射装置３０は、駆動源２１のシリンダ内に噴射する燃料量を調整することで、駆動源２１の出力を制御する。 As shown in FIG. 2, the work machine 1 includes a drive source 21, a transmission 24, and a traveling device 25. The drive source 21 is, for example, a diesel engine. The drive source 21 is provided with a fuel injection device 30. The fuel injection device 30 controls the output of the drive source 21 by adjusting the amount of fuel injected into the cylinder of the drive source 21.
　トランスミッション２４は、駆動源２１に接続される。トランスミッション２４は、駆動源２１からの駆動力を走行装置２５に伝達する。例えば、トランスミッション２４は、ＨＳＴであり、油圧ポンプ３８と油圧モータ３９とを含む。トランスミッション２４は、油圧ポンプ３８と油圧モータ３９とのそれぞれの容量を制御することで、変速比を無段階に変更可能である。トランスミッション２４は、クラッチ４０を含む。クラッチ４０は、係合状態と非係合状態とに切り替え可能である。トランスミッション２４は、クラッチ４０が係合状態で、走行装置２５へ駆動力を伝達する。トランスミッション２４は、クラッチ４０が非係合状態で、走行装置２５への駆動力を遮断する。 The transmission 24 is connected to the drive source 21. The transmission 24 transmits the drive force from the drive source 21 to the traveling device 25. For example, the transmission 24 is an HST and includes a hydraulic pump 38 and a hydraulic motor 39. The transmission 24 can continuously change the gear ratio by controlling the capacity of each of the hydraulic pump 38 and the hydraulic motor 39. The transmission 24 includes a clutch 40. The clutch 40 can be switched between an engaged state and a disengaged state. The transmission 24 transmits the drive force to the traveling device 25 when the clutch 40 is engaged. The transmission 24 cuts off the drive force to the traveling device 25 when the clutch 40 is disengaged.
　ただし、トランスミッション２４は、ＥＭＴ（Electric Mechanical Transmission）、或いはＨＭＴ（Hydraulic Mechanical Transmission）などの他の種類のトランスミッションであってもよい。或いは、トランスミッション２４は、トルクコンバータ及び複数の変速ギアを含むトランスミッションであってもよい。 However, the transmission 24 may be another type of transmission, such as an Electric Mechanical Transmission (EMT) or a Hydraulic Mechanical Transmission (HMT). Alternatively, the transmission 24 may be a transmission that includes a torque converter and multiple shift gears.
　走行装置２５は、車体２に搭載され、駆動源２１からの駆動力によって駆動されることで車体２を走行させる。走行装置２５は、アクスル２６，２７と、前輪２８Ａ，２８Ｂと、後輪２８Ｃ，２８Ｄとを含む。アクスル２６，２７は、トランスミッション２４に接続される。前輪２８Ａ，２８Ｂは、前車体２ａに設けられる。後輪２８Ｃ，２８Ｄは、後車体２ｂに設けられる。アクスル２６は、トランスミッション２４からの駆動力を前輪２８Ａ，２８Ｂに伝達する。アクスル２７は、トランスミッション２４からの駆動力を後輪２８Ｃ，２８Ｄに伝達する。 The running device 25 is mounted on the vehicle body 2 and is driven by the driving force from the drive source 21 to cause the vehicle body 2 to run. The running device 25 includes axles 26, 27, front wheels 28A, 28B, and rear wheels 28C, 28D. The axles 26, 27 are connected to the transmission 24. The front wheels 28A, 28B are provided on the front vehicle body 2a. The rear wheels 28C, 28D are provided on the rear vehicle body 2b. The axle 26 transmits the driving force from the transmission 24 to the front wheels 28A, 28B. The axle 27 transmits the driving force from the transmission 24 to the rear wheels 28C, 28D.
　作業機械１は、ＰＴＯ（Power Take Off）３１と、作業機ポンプ３２と、制御弁３３とを含む。ＰＴＯ３１は、トランスミッション２４と作業機ポンプ３２とに、駆動源２１の駆動力を分配する。なお、図２では、１つの作業機ポンプ３２のみが図示されている。しかし、２つ以上の油圧ポンプが、ＰＴＯ３１を介して駆動源２１に接続されてもよい。 The work machine 1 includes a PTO (Power Take Off) 31, a work implement pump 32, and a control valve 33. The PTO 31 distributes the driving force of the drive source 21 to the transmission 24 and the work implement pump 32. Note that only one work implement pump 32 is illustrated in FIG. 2. However, two or more hydraulic pumps may be connected to the drive source 21 via the PTO 31.
　作業機ポンプ３２は、ＰＴＯ３１を介して駆動源２１に接続される。作業機ポンプ３２は、油圧ポンプである。作業機ポンプ３２は、駆動源２１によって駆動され、作動油を吐出する。作業機ポンプ３２から吐出された作動油は、上述した油圧シリンダ１３－１５に供給される。制御弁３３は、作業機ポンプ３２から油圧シリンダ１３－１５に供給される作動油の流量を制御する。制御弁３３は、例えば、電磁比例制御弁であり、入力される電気信号に応じて、制御される。或いは、制御弁３３は、圧力比例制御弁であり、入力されるパイロット圧に応じて制御されてもよい。 The work implement pump 32 is connected to the drive source 21 via the PTO 31. The work implement pump 32 is a hydraulic pump. The work implement pump 32 is driven by the drive source 21 and discharges hydraulic oil. The hydraulic oil discharged from the work implement pump 32 is supplied to the hydraulic cylinders 13-15 described above. The control valve 33 controls the flow rate of the hydraulic oil supplied from the work implement pump 32 to the hydraulic cylinders 13-15. The control valve 33 is, for example, an electromagnetic proportional control valve, and is controlled in response to an input electrical signal. Alternatively, the control valve 33 may be a pressure proportional control valve, and is controlled in response to an input pilot pressure.
　作業機械１は、ブレーキポンプ３６と、ブレーキ装置３７Ａ－３７Ｄとを含む。ブレーキ装置３７Ａ－３７Ｄは、油圧式ブレーキである。ブレーキポンプ３６は、駆動源２１によって駆動され、作動油を吐出する。ブレーキポンプ３６から吐出された作動油は、ブレーキ装置３７Ａ－３７Ｄに供給される。ブレーキ装置３７Ａ－３７Ｄは、作動油によって駆動されることで走行装置２５を制動する。ブレーキ装置３７Ａ－３７Ｄは、例えば湿式多板ブレーキである。詳細には、ブレーキ装置３７Ａ－３７Ｄは、フロントブレーキ３７Ａ，３７Ｂとリアブレーキ３７Ｃ，３７Ｄとを含む。フロントブレーキ３７Ａ，３７Ｂは、前輪２８Ａ，２８Ｂを制動する。リアブレーキ３７Ｃ，３７Ｄは、後輪２８Ｃ，２８Ｄを制動する。 The work machine 1 includes a brake pump 36 and braking devices 37A-37D. The braking devices 37A-37D are hydraulic brakes. The brake pump 36 is driven by the drive source 21 and discharges hydraulic oil. The hydraulic oil discharged from the brake pump 36 is supplied to the braking devices 37A-37D. The braking devices 37A-37D are driven by the hydraulic oil to brake the traveling device 25. The braking devices 37A-37D are, for example, wet-type multi-plate brakes. In detail, the braking devices 37A-37D include front brakes 37A, 37B and rear brakes 37C, 37D. The front brakes 37A, 37B brake the front wheels 28A, 28B. The rear brakes 37C, 37D brake the rear wheels 28C, 28D.
　作業機械１は、エンジンセンサ３４と車速センサ３５とを含む。エンジンセンサ３４は、エンジン回転速度を検出する。車速センサ３５は、車速を検出する。車速センサ３５は、例えば、車速として、走行装置２５の出力回転速度を検出する。走行装置２５の出力回転速度は、作業機械１の車速に相当する。走行装置２５の出力回転速度は、例えば、トランスミッション２４の出力軸の回転速度である。ただし、出力回転速度は、トランスミッション２４内、或いはトランスミッション２４の下流に位置する他の回転要素の回転速度であってもよい。 The work machine 1 includes an engine sensor 34 and a vehicle speed sensor 35. The engine sensor 34 detects the engine rotation speed. The vehicle speed sensor 35 detects the vehicle speed. The vehicle speed sensor 35 detects, for example, the output rotation speed of the traveling device 25 as the vehicle speed. The output rotation speed of the traveling device 25 corresponds to the vehicle speed of the work machine 1. The output rotation speed of the traveling device 25 is, for example, the rotation speed of the output shaft of the transmission 24. However, the output rotation speed may also be the rotation speed of another rotating element located within the transmission 24 or downstream of the transmission 24.
　作業機械１は、コントローラ４１を含む。コントローラ４１は、ＣＰＵ（central processing unit）などのプロセッサと、ＲＡＭ及びＲＯＭなどの記憶装置とを含む。コントローラ４１は、ハードディスク、或いはＳＳＤ（Solid State Drive）などの補助記憶装置を含んでもよい。コントローラ４１は、作業機械１を制御するためのプログラム及びデータを記憶している。コントローラ４１は、記憶されているプログラム及びデータに従って、作業機械１を制御するための処理を実行する。 The work machine 1 includes a controller 41. The controller 41 includes a processor such as a CPU (central processing unit) and storage devices such as RAM and ROM. The controller 41 may include an auxiliary storage device such as a hard disk or an SSD (Solid State Drive). The controller 41 stores programs and data for controlling the work machine 1. The controller 41 executes processing for controlling the work machine 1 in accordance with the stored programs and data.
　コントローラ４１は、エンジンセンサ３４から、エンジン回転速度を示す信号を受信する。コントローラ４１は、車速センサ３５から、出力回転速度を示す信号を受信する。 The controller 41 receives a signal indicating the engine rotation speed from the engine sensor 34. The controller 41 receives a signal indicating the output rotation speed from the vehicle speed sensor 35.
　コントローラ４１は、駆動源２１に指令信号を送信することで、駆動源２１の出力を制御する。コントローラ４１は、トランスミッション２４に指令信号を送信することで、トランスミッション２４の前進ギアと後進ギアとを切り替える。コントローラ４１は、トランスミッション２４に指令信号を送信することで、トランスミッション２４の変速比を制御する。コントローラ４１は、トランスミッション２４に指令信号を送信することで、クラッチ４０を係合状態と非係合状態とに切り替える。コントローラ４１は、作業機ポンプ３２及び制御弁３３に指令信号を送信することで、作業機３を制御する。 The controller 41 controls the output of the drive source 21 by sending a command signal to the drive source 21. The controller 41 switches the transmission 24 between a forward gear and a reverse gear by sending a command signal to the transmission 24. The controller 41 controls the gear ratio of the transmission 24 by sending a command signal to the transmission 24. The controller 41 switches the clutch 40 between an engaged state and a disengaged state by sending a command signal to the transmission 24. The controller 41 controls the work implement 3 by sending a command signal to the work implement pump 32 and the control valve 33.
　作業機械１は、ＦＲ操作部材４２と、アクセル操作部材４３と、作業機操作部材４４と、ブレーキ操作部材４５と、設定装置４６とを含む。ＦＲ操作部材４２は、作業機械１の前進と後進とを切り替えるために、オペレータによって操作可能である。ＦＲ操作部材４２は、中立位置から前進位置と後進位置とに操作可能である。ＦＲ操作部材４２は、例えばレバーである。ただし、ＦＲ操作部材４２は、スイッチ、或いはペダルなどの他の部材であってもよい。 The work machine 1 includes an FR operating member 42, an accelerator operating member 43, a work equipment operating member 44, a brake operating member 45, and a setting device 46. The FR operating member 42 can be operated by an operator to switch the work machine 1 between forward and reverse. The FR operating member 42 can be operated from a neutral position to a forward position and a reverse position. The FR operating member 42 is, for example, a lever. However, the FR operating member 42 may also be another member such as a switch or a pedal.
　アクセル操作部材４３は、作業機械１の車速を制御するためにオペレータによって操作可能である。アクセル操作部材４３は、例えばペダルである。ただし、アクセル操作部材４３は、レバー、或いはスイッチなどの他の部材であってもよい。作業機操作部材４４は、作業機３を制御するためにオペレータによって操作可能である。作業機操作部材４４は、例えばレバーである。ただし、作業機操作部材４４は、スイッチ、或いはペダルなどの他の部材であってもよい。 The accelerator operating member 43 can be operated by an operator to control the vehicle speed of the work machine 1. The accelerator operating member 43 is, for example, a pedal. However, the accelerator operating member 43 may be another member such as a lever or a switch. The work machine operating member 44 can be operated by an operator to control the work machine 3. The work machine operating member 44 is, for example, a lever. However, the work machine operating member 44 may be another member such as a switch or a pedal.
　コントローラ４１は、ＦＲ操作部材４２から、ＦＲ操作部材４２の操作位置を示す信号を受信する。コントローラ４１は、ＦＲ操作部材４２からの信号に応じて、トランスミッション２４の前進ギアと後進ギアとを切り替える。コントローラ４１は、アクセル操作部材４３から、アクセル操作量を示す信号を受信する。アクセル操作量は、アクセル操作部材４３の操作量である。 The controller 41 receives a signal indicating the operating position of the FR operating member 42 from the FR operating member 42. The controller 41 switches between the forward gear and the reverse gear of the transmission 24 in response to the signal from the FR operating member 42. The controller 41 receives a signal indicating the accelerator operation amount from the accelerator operating member 43. The accelerator operation amount is the operation amount of the accelerator operating member 43.
　図３は、作業機械１の駆動力特性を示す図である。図３において、実線Ｆ１はアクセル操作量が１００％である場合の駆動力特性を示している。図３において、破線Ｆ２はアクセル操作量が０％である場合の駆動力特性を示している。コントローラ４１は、アクセル操作量と車速とに応じて、図３に示す駆動力特性が得られるように、駆動源２１とトランスミッション２４とを制御する。 Figure 3 is a diagram showing the driving force characteristics of the work machine 1. In Figure 3, the solid line F1 shows the driving force characteristics when the accelerator operation amount is 100%. In Figure 3, the dashed line F2 shows the driving force characteristics when the accelerator operation amount is 0%. The controller 41 controls the driving source 21 and the transmission 24 according to the accelerator operation amount and the vehicle speed so as to obtain the driving force characteristics shown in Figure 3.
　図３に示すように、駆動力は、正の値と負の値とを含む。正の値の駆動力は、作業機械１を走行させる正の駆動力を示す。負の値の駆動力は、作業機械１を制動する負の駆動力、すなわちトランスミッション２４からの慣性制動力を示す。慣性制動力は、いわゆるエンジンブレーキであり、トランスミッション２４及び駆動源２１の内部負荷による制動力である。 As shown in FIG. 3, the driving force includes positive and negative values. A positive driving force indicates a positive driving force that drives the work machine 1. A negative driving force indicates a negative driving force that brakes the work machine 1, i.e., an inertial braking force from the transmission 24. The inertial braking force is what is known as an engine brake, and is a braking force due to the internal load of the transmission 24 and the drive source 21.
　ブレーキ操作部材４５は、ブレーキ装置３７Ａ－３７Ｄを駆動させるためにオペレータによって操作可能である。ブレーキ操作部材４５は、例えばペダルである。ただし、ブレーキ操作部材４５は、レバー、或いはスイッチなどの他の部材であってもよい。ブレーキ操作部材４５の操作に応じて、ブレーキ装置３７Ａ－３７Ｄに供給される作動油の油圧が制御される。それにより。ブレーキ装置３７Ａ－３７Ｄは、ブレーキ操作部材４５の操作量に応じて制動力を発生させる。 The brake operating member 45 can be operated by an operator to drive the brake devices 37A-37D. The brake operating member 45 is, for example, a pedal. However, the brake operating member 45 may be another member such as a lever or a switch. The hydraulic pressure of the hydraulic oil supplied to the brake devices 37A-37D is controlled in response to the operation of the brake operating member 45. As a result, the brake devices 37A-37D generate a braking force in response to the amount of operation of the brake operating member 45.
　図４は、ブレーキ装置３７Ａ－３７Ｄを駆動するための油圧回路５０を示す図である。図４に示すように、油圧回路５０は、分流弁５１と、第１流路５２と、第２流路５３と、第３流路５４と、自動ブレーキ弁５５と、手動ブレーキ弁５６と、シャトル弁５７とを備える。分流弁５１は、上述したブレーキポンプ３６からの作動油を、第２流路５３と第３流路５４とに分流する。第１流路５２は、第２流路５３に接続されている。 FIG. 4 is a diagram showing a hydraulic circuit 50 for driving the brake devices 37A-37D. As shown in FIG. 4, the hydraulic circuit 50 includes a flow dividing valve 51, a first flow path 52, a second flow path 53, a third flow path 54, an automatic brake valve 55, a manual brake valve 56, and a shuttle valve 57. The flow dividing valve 51 divides the hydraulic oil from the brake pump 36 described above into the second flow path 53 and the third flow path 54. The first flow path 52 is connected to the second flow path 53.
　自動ブレーキ弁５５は、コントローラ４１に電気的に接続されている。自動ブレーキ弁５５は、例えば電磁弁であり、コントローラ４１からの指令信号に応じて電気的に制御される。自動ブレーキ弁５５は、コントローラ４１からの指令信号に応じて、自動ブレーキ弁５５から第１流路５２を介してブレーキ装置３７Ａ－３７Ｄに供給される油圧（以下、第１油圧と呼ぶ）を変更する。 The automatic brake valve 55 is electrically connected to the controller 41. The automatic brake valve 55 is, for example, a solenoid valve, and is electrically controlled in response to a command signal from the controller 41. In response to a command signal from the controller 41, the automatic brake valve 55 changes the hydraulic pressure (hereinafter referred to as the first hydraulic pressure) supplied from the automatic brake valve 55 to the brake devices 37A-37D via the first flow path 52.
　手動ブレーキ弁５６は、ブレーキ操作部材４５に接続されている。手動ブレーキ弁５６は、ブレーキ操作部材４５に、バネなどのリンク部材を介して、機械的に接続されている。手動ブレーキ弁５６は、第２流路５３と第３流路５４とに接続されている。手動ブレーキ弁５６は、ブレーキ操作部材４５の操作量に応じて、手動ブレーキ弁５６から、第２流路５３及び第３流路５４を介して、ブレーキ装置３７Ａ－３７Ｄに供給される油圧（以下、第２油圧と呼ぶ）を変更する。 The manual brake valve 56 is connected to the brake operating member 45. The manual brake valve 56 is mechanically connected to the brake operating member 45 via a link member such as a spring. The manual brake valve 56 is connected to the second flow path 53 and the third flow path 54. The manual brake valve 56 changes the hydraulic pressure (hereinafter referred to as the second hydraulic pressure) supplied from the manual brake valve 56 to the brake devices 37A-37D via the second flow path 53 and the third flow path 54 according to the amount of operation of the brake operating member 45.
　シャトル弁５７は、第１流路５２と第２流路５３と第３流路５４とに接続されている。シャトル弁５７は、自動ブレーキ弁５５からの第１油圧と、手動ブレーキ弁５６からの第２油圧とを、選択的にブレーキ装置３７Ａ－３７Ｄに供給する。詳細には、シャトル弁５７は、第１油圧と第２油圧とのうち大きい方をブレーキ装置３７Ａ－３７Ｄに供給する。従って、例えば、オペレータのブレーキ操作部材４５の操作による第１油圧が、コントローラ４１からの指令信号による第２油圧よりも大きい場合には、第１油圧がブレーキ装置３７Ａ－３７Ｄに供給される。それにより、オペレータのブレーキ操作部材４５の操作量に応じて、ブレーキ装置３７Ａ－３７Ｄの制動力が制御される。 The shuttle valve 57 is connected to the first flow path 52, the second flow path 53, and the third flow path 54. The shuttle valve 57 selectively supplies the first hydraulic pressure from the automatic brake valve 55 and the second hydraulic pressure from the manual brake valve 56 to the brake devices 37A-37D. In detail, the shuttle valve 57 supplies the larger of the first hydraulic pressure and the second hydraulic pressure to the brake devices 37A-37D. Therefore, for example, when the first hydraulic pressure due to the operation of the brake operating member 45 by the operator is larger than the second hydraulic pressure due to the command signal from the controller 41, the first hydraulic pressure is supplied to the brake devices 37A-37D. Thereby, the braking force of the brake devices 37A-37D is controlled according to the amount of operation of the brake operating member 45 by the operator.
　逆に、コントローラ４１からの指令信号による第２油圧が、オペレータのブレーキ操作部材４５の操作による第１油圧よりも大きい場合には、第２油圧がブレーキ装置３７Ａ－３７Ｄに供給される。それにより、コントローラ４１からの指令信号に応じて、ブレーキ装置３７Ａ－３７Ｄの制動力が制御される。 On the other hand, when the second hydraulic pressure based on the command signal from the controller 41 is greater than the first hydraulic pressure based on the operator's operation of the brake operating member 45, the second hydraulic pressure is supplied to the brake devices 37A-37D. This controls the braking force of the brake devices 37A-37D in response to the command signal from the controller 41.
　本実施形態に係る作業機械１では、コントローラ４１は、作業機械１の慣性走行時における制動力を自動的に制御する自動ブレーキ制御を実行する。作業機械１の慣性走行とは、アクセル操作部材４３とブレーキ操作部材４５とが操作されていない状態で、作業機械１が慣性により走行している状態を意味する。設定装置４６は、自動ブレーキ制御における慣性走行時の目標制動力を設定するためにオペレータによって操作可能である。設定装置４６は、例えばダイヤル式のスイッチである。ただし、設定装置は、スライド式のスイッチ、プッシュボタン式のスイッチ、或いはタッチパネルなどの他の装置であってもよい。設定装置４６は、オペレータによる操作に応じて、目標制動力を示す制動指令を出力する。 In the work machine 1 according to this embodiment, the controller 41 executes automatic brake control that automatically controls the braking force when the work machine 1 is running by inertia. The inertial running of the work machine 1 means a state in which the work machine 1 is running by inertia with the accelerator operating member 43 and the brake operating member 45 not being operated. The setting device 46 can be operated by an operator to set the target braking force during inertial running in the automatic brake control. The setting device 46 is, for example, a dial switch. However, the setting device may be other devices such as a slide switch, a push button switch, or a touch panel. The setting device 46 outputs a braking command indicating the target braking force in response to operation by the operator.
　目標制動力は、複数のレベルで示される。複数のレベルは、例えば第１レベルと第２レベルと第３レベルとを含む。第１レベルの目標制動力が最も大きく。第３レベルンも目標制動力が最も小さい。第２レベルの目標制動力は、第１レベルと第２レベルとの間の大きさである。 The target braking force is indicated in a plurality of levels. The plurality of levels includes, for example, a first level, a second level, and a third level. The first level has the largest target braking force. The third level has the smallest target braking force. The second level has a target braking force between the first and second levels.
　図５は、自動ブレーキ制御の処理を示すフローチャートである。図５に示すように、ステップＳ１０１で、コントローラ４１は、制動指令を取得する。コントローラ４１は、設定装置４６を用いてオペレータによって設定された目標制動力を示す制動指令を取得する。 FIG. 5 is a flowchart showing the process of automatic brake control. As shown in FIG. 5, in step S101, the controller 41 obtains a braking command. The controller 41 obtains a braking command indicating a target braking force set by the operator using the setting device 46.
　ステップＳ１０２では、コントローラ４１は、目標制動力を決定する。コントローラ４１は、設定装置４６からの制動指令に基づいて目標制動力を決定する。ステップＳ１０３では、コントローラ４１は、トランスミッション情報を取得する。トランスミッション情報は、トランスミッション２４の状態を示す。トランスミッション情報は、例えばトランスミッション２４の変速比を含む。トランスミッション情報は、車速を含む。トランスミッション２４がＨＳＴの場合、トランスミッション情報は、油圧ポンプの容量と油圧モータの容量とを含んでもよい。トランスミッション２４が複数の変速ギアを含む場合、トランスミッション情報は、変速ギアのギア比を含んでもよい。 In step S102, the controller 41 determines a target braking force. The controller 41 determines the target braking force based on a braking command from the setting device 46. In step S103, the controller 41 acquires transmission information. The transmission information indicates the state of the transmission 24. The transmission information includes, for example, the gear ratio of the transmission 24. The transmission information includes the vehicle speed. If the transmission 24 is an HST, the transmission information may include the capacity of the hydraulic pump and the capacity of the hydraulic motor. If the transmission 24 includes multiple shift gears, the transmission information may include the gear ratio of the shift gears.
　ステップＳ１０４で、コントローラ４１は、トランスミッション２４からの慣性制動力を算出する。コントローラ４１は、上述したトランスミッション情報に基づいて、トランスミッション２４からの慣性制動力を算出する。 In step S104, the controller 41 calculates the inertial braking force from the transmission 24. The controller 41 calculates the inertial braking force from the transmission 24 based on the above-mentioned transmission information.
　ステップＳ１０５で、コントローラ４１は、補助制動力を決定する。コントローラ４１は、トランスミッション２４からの慣性制動力と、ブレーキ装置３７Ａ－３７Ｄによる補助制動力とによって、目標制動力が得られるように、補助制動力を決定する。コントローラ４１は、目標制動力と慣性制動力との差分に相当する制動力を、補助制動力として決定する。 In step S105, the controller 41 determines the auxiliary braking force. The controller 41 determines the auxiliary braking force so that the target braking force is obtained by the inertial braking force from the transmission 24 and the auxiliary braking force from the brake devices 37A-37D. The controller 41 determines the braking force equivalent to the difference between the target braking force and the inertial braking force as the auxiliary braking force.
　ステップＳ１０６で、コントローラ４１は、自動ブレーキ弁５５を制御する。コントローラ４１は、補助制動力に相当するブレーキ装置３７Ａ－３７Ｄの目標ブレーキ油圧を算出する。コントローラ４１は、ブレーキ装置３７Ａ－３７Ｄに目標ブレーキ油圧が供給されるように、自動ブレーキ弁５５の開度を制御する。 In step S106, the controller 41 controls the automatic brake valve 55. The controller 41 calculates the target brake hydraulic pressure for the brake devices 37A-37D, which corresponds to the auxiliary braking force. The controller 41 controls the opening of the automatic brake valve 55 so that the target brake hydraulic pressure is supplied to the brake devices 37A-37D.
　ステップＳ１０７で、コントローラ４１は、トランスミッション２４が第１過回転状態であるかを判定する。コントローラ４１は、車速が第１閾値以上である場合に、トランスミッション２４が第１過回転状態であると判定する。コントローラ４１が、トランスミッション２４が第１過回転状態であると判定した場合には、処理はステップＳ１０８に進む。ステップＳ１０８で、コントローラ４１は、補助制動力を増大させる。例えば、コントローラ４１は、ブレーキ装置３７Ａ－３７Ｄの最大制動力まで補助制動力を増大させる。或いは、コントローラ４１は、補助制動力を段階的に増大させてもよい。 In step S107, the controller 41 determines whether the transmission 24 is in the first over-speed state. The controller 41 determines that the transmission 24 is in the first over-speed state when the vehicle speed is equal to or greater than the first threshold value. If the controller 41 determines that the transmission 24 is in the first over-speed state, the process proceeds to step S108. In step S108, the controller 41 increases the auxiliary braking force. For example, the controller 41 increases the auxiliary braking force to the maximum braking force of the brake devices 37A-37D. Alternatively, the controller 41 may increase the auxiliary braking force in stages.
　ステップＳ１０９で、コントローラ４１は、トランスミッション２４が第２過回転状態であるかを判定する。コントローラ４１は、車速が第２閾値以上である場合に、トランスミッション２４が第２過回転状態であると判定する。第２閾値は、第１閾値より大きい。コントローラ４１が、トランスミッション２４が第２過回転状態であると判定した場合には、処理はステップＳ１１０に進む。 In step S109, the controller 41 determines whether the transmission 24 is in a second over-speed state. The controller 41 determines that the transmission 24 is in a second over-speed state when the vehicle speed is equal to or greater than a second threshold value. The second threshold value is greater than the first threshold value. If the controller 41 determines that the transmission 24 is in a second over-speed state, the process proceeds to step S110.
　ステップＳ１１０で、コントローラ４１は、クラッチ４０を非係合状態に切り換える。それにより、走行装置２５からトランスミッション２４への駆動力の伝達が遮断される。第２閾値は、トランスミッション２４を過回転から保護する観点から定められる。第２閾値は、例えばトランスミッション２４の油圧モータ、油圧ポンプ、或いはエンジンの許容最大観点速度に基づいて定められる。第１閾値は、第２閾値よりも小さい。第１閾値は、トランスミッション２４が第２過回転状態となることを予防する観点から定められる。 In step S110, the controller 41 switches the clutch 40 to a disengaged state. This blocks the transmission of driving force from the travel device 25 to the transmission 24. The second threshold is determined from the perspective of protecting the transmission 24 from overspeed. The second threshold is determined based on, for example, the maximum allowable speed of the hydraulic motor, hydraulic pump, or engine of the transmission 24. The first threshold is smaller than the second threshold. The first threshold is determined from the perspective of preventing the transmission 24 from entering a second overspeed state.
　例えば、図６においてＬ１は、第１レベルの目標制動力の一例を示している。図７においてＬ２は、第２レベルの目標制動力の一例を示している。図８においてＬ３は、第３レベルの目標制動力の一例を示している。第１～第３レベルの目標制動力Ｌ１－Ｌ３と車速との関係を示すデータが、コントローラ４１に記憶されている。 For example, in FIG. 6, L1 shows an example of a first level target braking force. In FIG. 7, L2 shows an example of a second level target braking force. In FIG. 8, L3 shows an example of a third level target braking force. Data showing the relationship between the first to third level target braking forces L1-L3 and the vehicle speed is stored in the controller 41.
　図６に示すように、コントローラ４１は、設定装置４６によって目標制動力として第１レベルが設定されると、車速に応じた目標制動力Ｌ１を決定する。図６において、Ｌ０は、慣性走行時のトランスミッション２４からの慣性制動力を示している。コントローラ４１は、トランスミッション情報から慣性制動力Ｌ０を算出する。コントローラ４１は、目標制動力Ｌ１と慣性制動力Ｌ０との差分ｄＦに相当する補助制動力を発生させるように、ブレーキ装置３７Ａ－３７Ｄの目標ブレーキ油圧を算出する。コントローラ４１は、ブレーキ装置３７Ａ－３７Ｄに目標ブレーキ油圧が供給されるように、自動ブレーキ弁５５の開度を制御する。それにより、慣性制動力Ｌ０が第１レベルの目標制動力Ｌ１に対して不足していても、ブレーキ装置３７Ａ－３７Ｄによる補助制動力によって補われることで、第１レベルの目標制動力Ｌ１に従う制動力が得られる。 As shown in FIG. 6, when the first level is set as the target braking force by the setting device 46, the controller 41 determines a target braking force L1 according to the vehicle speed. In FIG. 6, L0 indicates the inertial braking force from the transmission 24 during inertial running. The controller 41 calculates the inertial braking force L0 from the transmission information. The controller 41 calculates the target brake oil pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference dF between the target braking force L1 and the inertial braking force L0. The controller 41 controls the opening degree of the automatic brake valve 55 so that the target brake oil pressure is supplied to the brake devices 37A-37D. As a result, even if the inertial braking force L0 is insufficient for the target braking force L1 of the first level, it is compensated for by the auxiliary braking force from the brake devices 37A-37D, and a braking force according to the target braking force L1 of the first level is obtained.
　図７に示すように、第２レベルの目標制動力Ｌ２は、第１レベルの目標制動力Ｌ１よりも小さい。コントローラ４１は、設定装置４６によって目標制動力として第２レベルが設定されると、車速に応じた目標制動力Ｌ２を決定する。以下、第１レベルが設定されている場合と同様に、コントローラ４１は、目標制動力Ｌ２と慣性制動力Ｌ０との差分に相当する補助制動力を発生させるように、ブレーキ装置３７Ａ－３７Ｄの目標ブレーキ油圧を算出し、目標ブレーキ油圧に従って自動ブレーキ弁５５の開度を制御する。 As shown in FIG. 7, the target braking force L2 of the second level is smaller than the target braking force L1 of the first level. When the second level is set as the target braking force by the setting device 46, the controller 41 determines the target braking force L2 according to the vehicle speed. Thereafter, in the same manner as when the first level is set, the controller 41 calculates the target brake hydraulic pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference between the target braking force L2 and the inertial braking force L0, and controls the opening of the automatic brake valve 55 according to the target brake hydraulic pressure.
　図８に示すように、第３レベルの目標制動力Ｌ３は、第２レベルの目標制動力Ｌ２よりも小さい。コントローラ４１は、設定装置４６によって目標制動力として第３レベルが設定されると、車速に応じた目標制動力Ｌ３を決定する。以下、第１レベルが設定されている場合と同様に、コントローラ４１は、目標制動力Ｌ３と慣性制動力Ｌ０との差分に相当する補助制動力を発生させるように、ブレーキ装置３７Ａ－３７Ｄの目標ブレーキ油圧を算出し、目標ブレーキ油圧に従って自動ブレーキ弁５５の開度を制御する。 As shown in FIG. 8, the target braking force L3 of the third level is smaller than the target braking force L2 of the second level. When the third level is set as the target braking force by the setting device 46, the controller 41 determines the target braking force L3 according to the vehicle speed. Thereafter, in the same manner as when the first level is set, the controller 41 calculates the target brake hydraulic pressure of the brake devices 37A-37D so as to generate an auxiliary braking force equivalent to the difference between the target braking force L3 and the inertial braking force L0, and controls the opening of the automatic brake valve 55 according to the target brake hydraulic pressure.
　以上のように、設定装置４６によって目標制動力を変更することで、慣性走行時の制動力を変更することができる。そのため、作業機械１が同じ下り坂を走行する場合に、慣性走行時に作業機械１が静定する車速を変更することができる。また、トランスミッション２４からの慣性制動力だけでは静定できない下り坂であっても、一定車速で走行することができる。なお、静定とは、作業機械１が慣性走行時に一定速度で走行する状態を意味する。 As described above, by changing the target braking force with the setting device 46, the braking force during inertial running can be changed. Therefore, when the work machine 1 runs on the same downhill slope, the vehicle speed at which the work machine 1 is stabilized during inertial running can be changed. Furthermore, even on a downhill slope that cannot be stabilized by the inertial braking force from the transmission 24 alone, the work machine 1 can run at a constant vehicle speed. Note that "stabilized" refers to a state in which the work machine 1 runs at a constant speed during inertial running.
　例えば、図６から図８に示すように、作業機械１が、ある下り坂を走行する場合に、作業機械１を加速させる力と釣り合う制動力（以下、静定制動力と呼ぶ）がＡ１であるものとする。トランスミッション２４からの慣性制動力Ｌ０が、静定制動力Ａ１がよりも小さい場合には、作業機械１は、トランスミッション２４からの慣性制動力だけでは静定することはできない。 For example, as shown in Figures 6 to 8, when the work machine 1 travels downhill, the braking force that balances the force accelerating the work machine 1 (hereinafter referred to as the static braking force) is assumed to be A1. If the inertial braking force L0 from the transmission 24 is smaller than the static braking force A1, the work machine 1 cannot be stabilized by the inertial braking force from the transmission 24 alone.
　そこで、図６に示すように、設定装置４６によって目標制動力をレベル１に設定することで、レベル１の目標制動力Ｌ１に相当する制動力が得られる。それにより、目標制動力Ｌ１が静定制動力Ａ１と釣り合う車速Ｖ１において、作業機械１は、一定速度で走行することができる。 As shown in FIG. 6, by setting the target braking force to level 1 using the setting device 46, a braking force equivalent to the target braking force L1 of level 1 is obtained. As a result, the work machine 1 can travel at a constant speed at a vehicle speed V1 where the target braking force L1 is balanced with the static braking force A1.
　図７に示すように、設定装置４６によって目標制動力をレベル２に設定することで、レベル２の目標制動力Ｌ２に相当する制動力が得られる。それにより、目標制動力Ｌ２が静定制動力Ａ１と釣り合う車速Ｖ２において、作業機械１は、一定速度で走行することができる。 As shown in FIG. 7, by setting the target braking force to level 2 using the setting device 46, a braking force equivalent to the target braking force L2 of level 2 is obtained. As a result, the work machine 1 can travel at a constant speed at a vehicle speed V2 where the target braking force L2 is balanced with the static braking force A1.
　また、図８に示すように、設定装置４６によって目標制動力をレベル３に設定することで、レベル３の目標制動力Ｌ３に相当する制動力が得られる。それにより、目標制動力Ｌ３が静定制動力Ａ１と釣り合う車速Ｖ３において、作業機械１は、一定速度で走行することができる。以上のように、作業機械１が同じ下り坂を走行する場合に、オペレータは設定装置４６によって目標制動力を変更することで、慣性走行時に作業機械１が静定する車速を変更することができる。 Also, as shown in FIG. 8, by setting the target braking force to level 3 using the setting device 46, a braking force equivalent to the target braking force L3 of level 3 can be obtained. This allows the work machine 1 to travel at a constant speed at a vehicle speed V3 where the target braking force L3 is balanced with the static braking force A1. As described above, when the work machine 1 travels on the same downhill slope, the operator can change the vehicle speed at which the work machine 1 is statically determined during inertial traveling by changing the target braking force using the setting device 46.
　作業機械１が急な下り坂を走行する場合には、図９に示すように、静定制動力Ａ２が、オペレータによって設定された目標制動力Ｌ２よりも大きい場合がある。この場合、作業機械１は、目標制動力Ｌ２では静定することはできず、車速が増大する。車速が増大し続けると、トランスミッション２４が過回転状態となり、トランスミッション２４がダメージを受ける恐れがある。 When the work machine 1 travels down a steep slope, as shown in FIG. 9, the static braking force A2 may be greater than the target braking force L2 set by the operator. In this case, the work machine 1 cannot be stabilized at the target braking force L2, and the vehicle speed increases. If the vehicle speed continues to increase, the transmission 24 may over-rev, and the transmission 24 may be damaged.
　本実施形態に係る作業機械では、車速が第１閾値Ｂ１以上となった場合に、コントローラ４１がブレーキ装置３７Ａ－３７Ｄによる補助制動力を増大させる。それにより、図９に示すように、静定制動力Ａ２よりも大きい制動力Ｃ１が得られることで、作業機械１が減速する。また、補助制動力を増大させるための第１閾値Ｂ１は、クラッチ４０が非係合状態に切り替えられる第２閾値Ｂ２よりも小さい。そのため、クラッチ４０が非係合状態となる前に、補助制動力を増大させることで、作業機械１を減速させることができる。それにより、作業機械１が走行不能となることが抑えられる。 In the work machine according to this embodiment, when the vehicle speed becomes equal to or greater than the first threshold value B1, the controller 41 increases the auxiliary braking force applied by the brake devices 37A-37D. This results in a braking force C1 greater than the static braking force A2, as shown in FIG. 9, and the work machine 1 decelerates. Furthermore, the first threshold value B1 for increasing the auxiliary braking force is smaller than the second threshold value B2 at which the clutch 40 is switched to a disengaged state. Therefore, by increasing the auxiliary braking force before the clutch 40 is disengaged, the work machine 1 can be decelerated. This prevents the work machine 1 from becoming unable to travel.
　以上説明した本実施形態に係る作業機械１では、目標制動力と慣性制動力との差分に基づいて、ブレーキ装置３７Ａ－３７Ｄによる制動力が制御される。そのため、慣性制動力が目標制動力に対して不足する場合に、ブレーキ装置３７Ａ－３７Ｄによる制動力によって、不足分を補うことができる。また、慣性制動力が変動しても、目標制動力が決定されることで、安定した制動力が得られる。それにより、作業機械１において、慣性制動力の不足、或いは変動に関わらず、安定した制動力が得られる。 In the work machine 1 according to the present embodiment described above, the braking force by the brake devices 37A-37D is controlled based on the difference between the target braking force and the inertial braking force. Therefore, when the inertial braking force is insufficient compared to the target braking force, the shortfall can be made up for by the braking force by the brake devices 37A-37D. Furthermore, even if the inertial braking force fluctuates, a stable braking force can be obtained by determining the target braking force. As a result, in the work machine 1, a stable braking force can be obtained regardless of a shortage or fluctuation of the inertial braking force.
　また、トランスミッション２４が第１過回転状態であると判定された場合には、補助制動力が増大される。それにより、例えば降坂時において、制動指令によって設定された目標制動力では、必要な制動力に不足する場合には、補助制動力が増大されることで、作業機械１が減速される。 In addition, if it is determined that the transmission 24 is in the first over-speed state, the auxiliary braking force is increased. As a result, when going downhill, for example, if the target braking force set by the braking command is insufficient to provide the necessary braking force, the auxiliary braking force is increased, and the work machine 1 is decelerated.
　以上、本発明の一実施形態について説明したが、本発明は上記実施形態に限定されるものではなく、発明の要旨を逸脱しない範囲で種々の変更が可能である。 Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the gist of the invention.
　作業機械１は、ホイールローダに限らず、ブルドーザ、或いはモータグレーダなどの他の機械であってもよい。作業機械１は、遠隔から操作可能であってもよい。その場合、ＦＲ操作部材４２、アクセル操作部材４３、作業機操作部材４４、ブレーキ操作部材４５、及び設定装置４６は、作業機械１の外部に配置されてもよい。 The work machine 1 is not limited to a wheel loader, but may be other machines such as a bulldozer or a motor grader. The work machine 1 may be operable remotely. In that case, the FR operation member 42, the accelerator operation member 43, the work machine operation member 44, the brake operation member 45, and the setting device 46 may be disposed outside the work machine 1.
　駆動源２１は、エンジンに限らず、電動モータを含んでもよい。コントローラ４１は、複数のコントローラによって構成されてもよい。上述した作業機械１の制御の処理は、複数のコントローラに分散して実行されてもよい。 The driving source 21 is not limited to an engine, and may include an electric motor. The controller 41 may be composed of multiple controllers. The above-mentioned control processing of the work machine 1 may be distributed and executed by multiple controllers.
　自動ブレーキ制御の処理は、上述した実施形態のものに限らず、変更されてもよい。例えば、目標制動力のレベルの数は３つに限らない。目標制動力のレベルの数は３つより多くてもよく、或いは３つより少なくてもよい。目標制動力は、制動力の数値で示されてもよい。 The automatic brake control process is not limited to that of the above-described embodiment, and may be modified. For example, the number of levels of the target braking force is not limited to three. The number of levels of the target braking force may be more than three, or less than three. The target braking force may be indicated by a numerical value of the braking force.
　図１０は、変形例に係る自動ブレーキ制御の処理を示すフローチャートである。図１０においてステップＳ２０１～Ｓ２０６は、上述した実施形態のステップＳ１０１～Ｓ１０６と同様である。ステップＳ２０７で、コントローラ４１は、トランスミッション２４が過回転状態であるかを判定する。コントローラ４１は、車速が上述した第２閾値Ｂ２以上である場合に、トランスミッション２４が過回転状態であると判定する。コントローラ４１が、トランスミッション２４が過回転状態であると判定した場合には、処理はステップＳ２０８に進む。 FIG. 10 is a flowchart showing the process of automatic brake control according to the modified example. In FIG. 10, steps S201 to S206 are similar to steps S101 to S106 in the above-described embodiment. In step S207, the controller 41 determines whether the transmission 24 is in an overspeed state. The controller 41 determines that the transmission 24 is in an overspeed state when the vehicle speed is equal to or greater than the above-described second threshold value B2. If the controller 41 determines that the transmission 24 is in an overspeed state, the process proceeds to step S208.
　ステップＳ２０８で、コントローラ４１は、クラッチ４０を非係合状態に切り換える。また、ステップＳ２０９で、コントローラ４１は、補助制動力を増大させる。すなわち、図１１に示すように、コントローラ４１は、車速が、クラッチ４０を非係合状態に切り換える第２閾値Ｂ２以上である場合に、補助制動力を増大させる。それにより、トランスミッション２４から走行装置２５への駆動力の伝達が遮断された状態で、ブレーキ装置３７Ａ－３７Ｄによる制動力Ｃ２によって、作業機械１を減速させることができる。 In step S208, the controller 41 switches the clutch 40 to a disengaged state. In addition, in step S209, the controller 41 increases the auxiliary braking force. That is, as shown in FIG. 11, the controller 41 increases the auxiliary braking force when the vehicle speed is equal to or greater than the second threshold value B2 at which the clutch 40 is switched to a disengaged state. This makes it possible to decelerate the work machine 1 by the braking force C2 applied by the brake devices 37A-37D with the transmission of driving force from the transmission 24 to the traveling device 25 cut off.
　本開示によれば、作業機械において、慣性制動力の不足、或いは変動に関わらず、安定した制動力を得ることができる。 According to this disclosure, a stable braking force can be obtained in a work machine regardless of a lack of or fluctuation in the inertial braking force.
２１：駆動源
２４：トランスミッション
２５：走行装置
３７Ａ：ブレーキ装置
４１：コントローラ
４５：ブレーキ操作部材
４６：設定装置
５５：自動ブレーキ弁
５６：手動ブレーキ弁
５７：シャトル弁 21: Drive source 24: Transmission 25: Travel device 37A: Brake device 41: Controller 45: Brake operation member 46: Setting device 55: Automatic brake valve 56: Manual brake valve 57: Shuttle valve

Claims (15)

  1. 　作業機械であって、
    　駆動源と、
    　前記駆動源に接続されるトランスミッションと、
    　前記トランスミッションに接続され、前記作業機械を走行させる走行装置と、
    　前記走行装置を制動するブレーキ装置と、
    　コントローラと、
    を備え、
    　前記コントローラは、
    　　前記作業機械を制動するための制動指令を取得し、
    　　前記制動指令に基づいて前記作業機械の慣性走行時における目標制動力を決定し、
    　　前記トランスミッションからの慣性制動力と、前記ブレーキ装置による補助制動力とによって前記目標制動力が得られるように、前記補助制動力を決定し、
    　　前記トランスミッションが過回転状態であるかを判定し、
    　　前記トランスミッションが前記過回転状態であると判定した場合には、前記補助制動力を増大させる、
    作業機械。     A work machine, comprising:
    A driving source;
    a transmission connected to the drive source;
    a travel device connected to the transmission for traveling the work machine;
    A brake device that brakes the traveling device;
    A controller;
    Equipped with
    The controller:
    obtaining a braking command for braking the work machine;
    determining a target braking force during inertial traveling of the work machine based on the braking command;
    determining an auxiliary braking force such that the target braking force is obtained by an inertial braking force from the transmission and an auxiliary braking force from the brake device;
    determining whether the transmission is in an overspeed condition;
    When it is determined that the transmission is in the overspeed state, the auxiliary braking force is increased.
    Working machinery.
  2. 　前記コントローラは、
    　　前記作業機械の車速を取得し、
    　　前記車速が第１閾値以上である場合に、前記トランスミッションが過回転状態であると判定して、前記補助制動力を増大させる、
    請求項１に記載の作業機械。     The controller:
    Acquire a vehicle speed of the work machine;
    When the vehicle speed is equal to or higher than a first threshold value, it is determined that the transmission is in an overspeed state, and the auxiliary braking force is increased.
    2. The work machine of claim 1.
  3. 　前記トランスミッションは、係合状態と非係合状態とに切り替え可能なクラッチを含み、
    　前記トランスミッションは、前記クラッチが前記係合状態で、前記走行装置へ駆動力を伝達し、前記クラッチが前記非係合状態で、前記走行装置への駆動力を遮断し、
    　前記コントローラは、
    　　前記車速が第１閾値以上である場合に、前記トランスミッションが第１過回転状態であると判定して、前記補助制動力を増大させ、
    　　前記車速が前記第１閾値より大きい第２閾値以上である場合に、前記トランスミッションが第２過回転状態であると判定して、前記クラッチを前記非係合状態に切り換える、
    請求項１に記載の作業機械。     The transmission includes a clutch that is switchable between an engaged state and a disengaged state,
    The transmission transmits a driving force to the traveling device when the clutch is in the engaged state, and cuts off the driving force to the traveling device when the clutch is in the disengaged state.
    The controller:
    When the vehicle speed is equal to or greater than a first threshold value, it is determined that the transmission is in a first over-speed state, and the auxiliary braking force is increased;
    when the vehicle speed is equal to or greater than a second threshold value that is greater than the first threshold value, it is determined that the transmission is in a second overspeed state, and the clutch is switched to the disengaged state.
    2. The work machine of claim 1.
  4. 　前記トランスミッションは、係合状態と非係合状態とに切り替え可能なクラッチを含み、
    　前記トランスミッションは、前記クラッチが、前記係合状態で前記走行装置へ駆動力を伝達し、前記クラッチが、前記非係合状態で前記走行装置への駆動力を遮断し、
    　前記コントローラは、
    　　前記車速が所定の閾値以上である場合に、前記トランスミッションが過回転状態であると判定して、前記クラッチを前記非係合状態に切り換え、
    　　前記車速が前記所定の閾値以上である場合に、前記補助制動力を増大させる、
    請求項１に記載の作業機械。     The transmission includes a clutch that is switchable between an engaged state and a disengaged state,
    The transmission has a clutch that transmits a driving force to the traveling device in the engaged state and a clutch that cuts off the driving force to the traveling device in the disengaged state.
    The controller:
    When the vehicle speed is equal to or greater than a predetermined threshold value, it is determined that the transmission is in an overspeed state, and the clutch is switched to the disengaged state;
    When the vehicle speed is equal to or greater than the predetermined threshold, the auxiliary braking force is increased.
    2. The work machine of claim 1.
  5. 　前記コントローラは、
    　　前記トランスミッションの状態を示すトランスミッション情報を取得し、
    　　前記トランスミッション情報に基づいて前記トランスミッションからの前記慣性制動力を算出し、
    　　前記目標制動力と前記慣性制動力との差分に基づいて、前記ブレーキ装置による前記補助制動力を決定する、
    請求項１に記載の作業機械。     The controller:
    obtaining transmission information indicative of a state of the transmission;
    Calculating the inertial braking force from the transmission based on the transmission information;
    determining the auxiliary braking force to be applied by the brake device based on a difference between the target braking force and the inertial braking force;
    2. The work machine of claim 1.
  6. 　前記目標制動力を設定するためにオペレータによって操作可能な設定装置をさらに備え、
    　前記コントローラは、前記設定装置の操作に応じた前記制動指令を取得する、
    請求項１に記載の作業機械。     a setting device operable by an operator to set the target braking force,
    The controller obtains the braking command in response to an operation of the setting device.
    2. The work machine of claim 1.
  7. 　前記ブレーキ装置は、油圧式ブレーキであり、
    　前記コントローラによって制御されることで前記ブレーキ装置への第１油圧を変更する自動ブレーキ弁をさらに備え、
    　前記コントローラは、前記目標制動力と前記慣性制動力との差分に応じて前記ブレーキ装置への前記第１油圧を変更するように、前記自動ブレーキ弁を制御する、
    請求項５に記載の作業機械。     The brake device is a hydraulic brake,
    an automatic brake valve that is controlled by the controller to change a first hydraulic pressure to the brake device;
    The controller controls the automatic brake valve so as to change the first hydraulic pressure applied to the brake device in accordance with a difference between the target braking force and the inertial braking force.
    6. A work machine according to claim 5.
  8. 　前記ブレーキ装置による制動力を調整するためにオペレータによって操作可能なブレーキ操作部材と、
    　前記ブレーキ操作部材の操作に応じて前記ブレーキ装置への第２油圧を変更する手動ブレーキ弁と、
    　前記自動ブレーキ弁からの前記第１油圧と、前記手動ブレーキ弁からの前記第２油圧とを選択的に前記ブレーキ装置に供給するシャトル弁と、
    をさらに備える請求項７に記載の作業機械。     a brake operating member operable by an operator to adjust the braking force applied by the brake device;
    a manual brake valve for changing the second hydraulic pressure applied to the brake device in response to operation of the brake operating member;
    a shuttle valve that selectively supplies the first hydraulic pressure from the automatic brake valve and the second hydraulic pressure from the manual brake valve to the brake device;
    The work machine of claim 7 further comprising:
  9. 　前記シャトル弁は、前記第１油圧と前記第２油圧とのうち大きい方を前記ブレーキ装置に供給する、
    請求項８に記載の作業機械。     The shuttle valve supplies the larger of the first hydraulic pressure and the second hydraulic pressure to the brake device.
    9. A work machine according to claim 8.
  10. 　駆動源と、前記駆動源に接続されるトランスミッションと、前記トランスミッションに接続され、前記作業機械を走行させる走行装置と、前記走行装置を制動するブレーキ装置と、を備える作業機械を制御するための方法であって、
    　前記作業機械を制動するための制動指令を取得することと、
    　前記制動指令に基づいて前記作業機械の慣性走行時における目標制動力を決定することと、
    　前記トランスミッションからの慣性制動力と、前記ブレーキ装置による補助制動力とによって前記目標制動力が得られるように、前記補助制動力を決定することと、
    　前記トランスミッションが過回転状態であるかを判定することと、
    　前記トランスミッションが前記過回転状態であると判定した場合には、前記補助制動力を増大させること、
    を備える方法。     A method for controlling a work machine including a drive source, a transmission connected to the drive source, a travel device connected to the transmission for traveling the work machine, and a brake device for braking the travel device, comprising:
    obtaining a braking command for braking the work machine;
    determining a target braking force during inertial traveling of the work machine based on the braking command;
    determining an auxiliary braking force such that the target braking force is obtained by an inertial braking force from the transmission and an auxiliary braking force from the brake device;
    determining whether the transmission is in an overspeed condition;
    increasing the auxiliary braking force when it is determined that the transmission is in the overspeed state;
    A method for providing the above.
  11. 　前記作業機械の車速を取得することと、
    　前記車速が第１閾値以上である場合に、前記トランスミッションが過回転状態であると判定して、前記補助制動力を増大させること、
    を備える請求項１０に記載の方法。     Obtaining a vehicle speed of the work machine;
    When the vehicle speed is equal to or higher than a first threshold value, determining that the transmission is in an overspeed state and increasing the auxiliary braking force;
    The method of claim 10 comprising:
  12. 　前記トランスミッションは、係合状態と非係合状態とに切り替え可能なクラッチを含み、
    　前記トランスミッションは、前記クラッチが前記係合状態で、前記走行装置へ駆動力を伝達し、前記クラッチが前記非係合状態で、前記走行装置への駆動力を遮断し、
    　前記車速が第１閾値以上である場合に、前記トランスミッションが第１過回転状態であると判定して、前記補助制動力を増大させることと、
    　前記車速が前記第１閾値より大きい第２閾値以上である場合に、前記トランスミッションが第２過回転状態であると判定して、前記クラッチを前記非係合状態に切り換えること、
    を備える請求項１０に記載の方法。     The transmission includes a clutch that is switchable between an engaged state and a disengaged state,
    The transmission transmits a driving force to the traveling device when the clutch is in the engaged state, and cuts off the driving force to the traveling device when the clutch is in the disengaged state.
    When the vehicle speed is equal to or greater than a first threshold value, determining that the transmission is in a first over-speed state, and increasing the auxiliary braking force.
    determining that the transmission is in a second overspeed state when the vehicle speed is equal to or greater than a second threshold value that is greater than the first threshold value, and switching the clutch to the disengaged state;
    The method of claim 10 comprising:
  13. 　前記トランスミッションは、係合状態と非係合状態とに切り替え可能なクラッチを含み、
    　前記トランスミッションは、前記クラッチが前記係合状態で、前記走行装置へ駆動力を伝達し、前記クラッチが前記非係合状態で、前記走行装置への駆動力を遮断し、
    　前記車速が所定の閾値以上である場合に、前記トランスミッションが過回転状態であると判定して、前記クラッチを前記非係合状態に切り換えることと、
    　前記車速が前記所定の閾値以上である場合に、前記補助制動力を増大させること、
    を備える請求項１０に記載の方法。     The transmission includes a clutch that is switchable between an engaged state and a disengaged state,
    The transmission transmits a driving force to the traveling device when the clutch is in the engaged state, and cuts off the driving force to the traveling device when the clutch is in the disengaged state.
    When the vehicle speed is equal to or greater than a predetermined threshold value, determining that the transmission is in an overspeed state and switching the clutch to the disengaged state;
    increasing the auxiliary braking force when the vehicle speed is equal to or greater than the predetermined threshold value;
    The method of claim 10 comprising:
  14. 　前記トランスミッションの状態を示すトランスミッション情報を取得することと、
    　前記トランスミッション情報に基づいて前記トランスミッションからの前記慣性制動力を算出することと、
    　前記目標制動力と前記慣性制動力との差分に基づいて、前記ブレーキ装置による前記補助制動力を決定すること、
    を備える請求項１０に記載の方法。     obtaining transmission information indicative of a state of the transmission;
    calculating the inertial braking force from the transmission based on the transmission information;
    determining the auxiliary braking force by the brake device based on a difference between the target braking force and the inertial braking force;
    The method of claim 10 comprising:
  15. 　前記目標制動力を設定するためにオペレータによって操作可能な設定装置から、前記設定装置の操作に応じた前記制動指令を取得すること、
    を備える請求項１０に記載の方法。
          acquiring, from a setting device operable by an operator to set the target braking force, the braking command corresponding to an operation of the setting device;
    The method of claim 10 comprising:
PCT/JP2023/033259 2022-11-30 2023-09-12 Work machine and method for controlling work machine WO2024116544A1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996020336A1 (en) * 1994-12-27 1996-07-04 Komatsu Ltd. Device and method for limiting the vehicle speed of a working vehicle
JP2005324711A (en) * 2004-05-14 2005-11-24 Advics:Kk Braking device for vehicle
JP2006199153A (en) * 2005-01-20 2006-08-03 Toyota Motor Corp Brake control device of vehicle
JP2009001268A (en) * 2007-06-20 2009-01-08 Ford Global Technologies Llc Hybrid propulsion system for vehicle
JP2011218872A (en) * 2010-04-05 2011-11-04 Toyota Motor Corp Brake control system

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996020336A1 (en) * 1994-12-27 1996-07-04 Komatsu Ltd. Device and method for limiting the vehicle speed of a working vehicle
JP2005324711A (en) * 2004-05-14 2005-11-24 Advics:Kk Braking device for vehicle
JP2006199153A (en) * 2005-01-20 2006-08-03 Toyota Motor Corp Brake control device of vehicle
JP2009001268A (en) * 2007-06-20 2009-01-08 Ford Global Technologies Llc Hybrid propulsion system for vehicle
JP2011218872A (en) * 2010-04-05 2011-11-04 Toyota Motor Corp Brake control system

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