JP2022170460A - Work machine, and method for controlling work machine - Google Patents

Abstract

To easily and appropriately adjust a pitch angle of a blade in a work machine.SOLUTION: A lift frame is supported on a vehicle body so as to be rotatable around a lift shaft. A blade is rotatably supported on the lift frame so as to be rotatable around a pitch shaft. A lift actuator is connected to the lift frame and the vehicle body, and vertically lift-operates the lift frame around the lift shaft. A pitch actuator is connected to the blade and the lift frame, and pitch-operates the blade around the pitch shaft. A sensor detects a height of the blade from a reference height determined based on the vehicle body. A controller controls the pitch actuator so as to change a pitch angle of the blade according to a height of the blade.SELECTED DRAWING: Figure 5

Description

The present invention relates to work machines and methods for controlling work machines.

Some work machines can adjust the pitch angle of the blade according to the operation of the operator. For example, the work machine disclosed in Patent Document 1 is provided with an operation lever for adjusting the pitch angle of the blade. A switch is provided on the operating lever. When the switch is on and the operating lever is pushed to the right, the hydraulic cylinder is controlled so that the blade pitch dumps (tilts forward). When the switch is on and the operating lever is pushed to the left, the hydraulic cylinder is controlled so that the blade pitches back (rearward tilt).

JP-A-7-252859

The pitch angle of the blade affects workability such as excavation or leveling. However, the pitch angle of the blade differs depending on the type of work. For example, when the pitch angle is large, that is, when the blade is tilted forward, ground leveling is good, but digging resistance is high and digging is poor. When the pitch angle is small, that is, when the blade is tilted backward, the excavation resistance is small and the excavation performance is good.

Therefore, it is not easy for even a skilled operator to manually select an appropriate pitch angle accurately. An object of the present disclosure is to enable easy and appropriate adjustment of the pitch angle of blades in a work machine.

A work machine according to a first aspect of the present disclosure includes a vehicle body, a lift frame, a blade, a lift actuator, a pitch actuator, a sensor, and a controller. The lift frame is supported rotatably around the lift shaft with respect to the vehicle body. The blade is rotatably supported about the pitch axis with respect to the lift frame. The lift actuator is connected to the lift frame and the vehicle body, and lifts the lift frame up and down around the lift axis. A pitch actuator is connected to the blade and the lift frame for pitching the blade about the pitch axis. A sensor detects the height of the blade from a reference height determined based on the vehicle body. The controller controls the pitch actuator to change the pitch angle of the blade according to the height of the blade.

A method according to a second aspect of the present disclosure is a method for controlling a work machine. A work machine includes a vehicle body, a lift frame, a blade, a lift actuator, and a pitch actuator. The lift frame is supported rotatably around the lift shaft with respect to the vehicle body. The blade is rotatably supported about the pitch axis with respect to the lift frame. The lift actuator is connected to the lift frame and the vehicle body, and lifts the lift frame up and down around the lift axis. A pitch actuator is connected to the blade and the lift frame for pitching the blade about the pitch axis. The method includes detecting the height of the blade from a reference height determined based on the vehicle body, and controlling a pitch actuator to change the pitch angle of the blade according to the height of the blade. Prepare.

According to the present disclosure, the pitch actuator is automatically controlled to change the pitch angle of the blade depending on the height of the blade. Thereby, the pitch angle of the blade can be easily and appropriately adjusted in the work machine.

It is a side view showing a working machine according to an embodiment. 1 is a block diagram showing the configuration of a drive system and a control system of a working machine; FIG. FIG. 10 is a diagram showing the height of the blade from the reference height; It is a figure which shows the pitch angle of a blade. It is a figure which shows an example of pitch angle data. FIG. 10 is a diagram showing the pitch motion of the blade when the height of the blade is equal to or greater than the reference height; FIG. 10 is a diagram showing the pitch motion of the blade when the height of the blade is below the reference height;

Hereinafter, working machines according to embodiments will be described with reference to the drawings. FIG. 1 is a side view showing a work machine 1 according to the embodiment. A working machine 1 according to this embodiment is a bulldozer. The working machine 1 includes a vehicle body 11 and a working machine 12 .

The vehicle body 11 includes an operator's cab 13 , an engine room 14 , and a travel device 15 . A driver's seat (not shown) is arranged in the driver's cab 13 . The engine room 14 is arranged in front of the operator's room 13 . The travel device 15 is provided under the vehicle body 11 . Traveling device 15 includes a pair of left and right crawler belts 16 . Note that FIG. 1 shows only the left crawler belt 16 . The work machine 1 travels as the crawler belt 16 rotates.

The working machine 12 is attached to the vehicle body 11 . The work implement 12 has a lift frame 17 , a blade 18 , a lift actuator 19 and a pitch actuator 20 . The lift frame 17 is rotatably supported with respect to the vehicle body 11 about the lift axis X1. The lift axis X1 extends in the lateral direction of the vehicle body 11. As shown in FIG. The lift frame 17 lifts up and down by rotating around the lift axis X1.

The blade 18 is arranged in front of the vehicle body 11 . The blade 18 is rotatably supported on the lift frame 17 about the pitch axis X2. The pitch axis X2 extends in the lateral direction of the vehicle body 11. As shown in FIG. The blade 18 pitches back and forth by rotating around the pitch axis X2. The blade 18 moves up and down as the lift frame 17 moves up and down.

A lift actuator 19 is connected to the vehicle body 11 and the lift frame 17 . Lift actuator 19 is a hydraulic cylinder. As the lift actuator 19 expands and contracts, the lift frame 17 lifts up and down. The retraction of the lift actuator 19 raises the blade 18 . Extending the lift actuator 19 lowers the blade 18 .

Pitch actuator 20 is connected to lift frame 17 and blade 18 . Pitch actuator 20 is a hydraulic cylinder. The extension and contraction of the pitch actuator 20 causes the blade 18 to pitch forward and backward. A portion of the blade 18, for example, the upper end, moves back and forth, causing the blade 18 to pitch around the pitch axis X2. Extension of the pitch actuator 20 causes the blade 18 to tilt forward. The retraction of the pitch actuator 20 causes the blade 18 to tilt back.

FIG. 2 is a block diagram showing the configuration of the drive system 2 and control system 3 of the work machine 1. As shown in FIG. As shown in FIG. 2 , the drive system 2 includes an engine 22 , a hydraulic pump 23 and a power transmission device 24 . The hydraulic pump 23 is driven by the engine 22 and discharges hydraulic oil. Hydraulic oil discharged from the hydraulic pump 23 is supplied to the lift actuator 19 and the pitch actuator 20 . Although one hydraulic pump is illustrated in FIG. 2, a plurality of hydraulic pumps may be provided.

The power transmission device 24 transmits the driving force of the engine 22 to the travel device 15 . The power transmission device 24 may be, for example, an HST (Hydro Static Transmission). Alternatively, the power transmission device 24 may be, for example, a torque converter or a transmission with multiple gears.

The control system 3 comprises a controller 26 and a control valve 27 . Controller 26 is programmed to control work machine 1 based on the acquired data. Controller 26 includes storage device 28 and processor 29 . Processor 29 includes, for example, a CPU. Storage device 28 includes, for example, a memory and an auxiliary storage device. The storage device 28 may be, for example, RAM or ROM. The storage device 28 may be a semiconductor memory, hard disk, or the like. Storage device 28 is an example of a non-transitory computer-readable recording medium. Storage device 28 stores computer instructions executable by processor 29 to control work machine 1 .

Control valve 27 is a proportional control valve and is controlled by a command signal from controller 26 . Control valve 27 is positioned between hydraulic actuators, such as lift actuator 19 and pitch actuator 20 , and hydraulic pump 23 . The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the lift actuator 19 . The control valve 27 controls the flow rate of hydraulic oil supplied from the hydraulic pump 23 to the pitch actuator 20 . Note that the control valve 27 may be a pressure proportional control valve. Alternatively, the control valve 27 may be an electromagnetic proportional control valve.

The control system 3 includes an operating device 31 and an input device 32 . The operating device 31 includes, for example, a lever. Alternatively, the operating device 31 may include pedals or switches. An operator can use the operation device 31 to manually operate the travel of the work machine 1 and the operation of the work machine 12 . The operation device 31 outputs an operation signal indicating the operation of the operation device 31 . The controller 26 receives operation signals from the operation device 31 .

The operating device 31 can operate the lift operation of the blade 18 . Specifically, the operating device 31 can operate the blade 18 to raise and lower it. When the operator performs a lifting operation on the operating device 31, the controller 26 controls the lift actuator 19 so that the blade 18 is lifted. When the operator performs a lowering operation on the operating device 31, the controller 26 controls the lift actuator 19 so that the blade 18 is lowered.

The operating device 31 can operate the pitch motion of the blade 18 . Specifically, the operating device 31 can operate the blade 18 to tilt forward and backward. When the operator tilts the operation device 31 forward, the controller 26 controls the pitch actuator 20 so that the blade 18 tilts forward. When the operator tilts the operation device 31 backward, the controller 26 controls the pitch actuator 20 so that the blade 18 tilts backward.

Note that the operating device 31 may be a hydraulic pilot type device. For example, the operating device 31 may output pilot hydraulic pressure according to the operation of the operating device 31 . The lift actuator 19 or the pitch actuator 20 may be controlled by controlling the control valve 27 with the pilot hydraulic pressure from the operating device 31 . The controller 26 may receive a signal indicating the pilot oil pressure as the operation signal.

The input device 32 includes, for example, a touch panel. However, input device 32 may include other devices such as switches. The operator can use the operation device 31 to set the control mode of the pitch angle of the blade 18 by the controller 26 . A control mode for the pitch angle of the blades 18 will be described later in detail.

The control system 3 has a sensor 33 that detects the height of the blade 18 . Sensors 33 include vehicle body sensors 34 , frame sensors 35 and blade sensors 36 . The vehicle body sensor 34 is attached to the vehicle body 11 . The vehicle body sensor 34 detects the attitude of the vehicle body 11 . A frame sensor 35 is attached to the lift frame 17 . A frame sensor 35 detects the posture of the lift frame 17 . A blade sensor 36 is attached to the blade 18 . A blade sensor 36 detects the attitude of the blade 18 .

The vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 are each an IMU (Inertial Measurement Unit). However, the frame sensor 35 and the blade sensor 36 are not limited to the IMU, and may be other sensors such as an angle sensor or a cylinder stroke sensor.

The vehicle body sensor 34 detects an angle (vehicle pitch angle) of the vehicle body 11 in the front-rear direction with respect to the horizontal. A frame sensor 35 detects the rotation angle of the lift frame 17 . A blade sensor 36 detects the pitch angle of the blade 18 . The vehicle body sensor 34, the frame sensor 35, and the blade sensor 36 each output a detection signal indicating the detected angle.

Controller 26 receives detection signals from vehicle body sensor 34 , frame sensor 35 and blade sensor 36 . The controller 26 calculates the height of the blade 18 from the reference height H0 determined based on the vehicle body 11 based on the detection signal. As shown in FIG. 3, the reference height H0 is the height of the ground contact surface G1 of the crawler belt 16. As shown in FIG. The height of the blade 18 is the height of the cutting edge P0 of the blade 18 from the ground plane G1.

The controller 26 stores machine dimension data indicating dimensions and positional relationships among the vehicle body 11 , the lift frame 17 and the blades 18 . The controller 26 calculates the height of the blade 18 from the reference height H0 based on the angles detected by the vehicle body sensor 34, the frame sensor 35, and the blade sensor 36, and the machine dimension data.

As shown in FIG. 3, the height of the blade 18 is zero when the cutting edge P0 of the blade 18 is placed on the ground contact surface G1 of the crawler belt 16. As shown in FIG. When the cutting edge P0 of the blade 18 is positioned above the ground contact surface G1 of the crawler belt 16, the height of the blade 18 is a positive value. When the cutting edge P0 of the blade 18 is positioned below the ground contact surface G1 of the crawler belt 16, the height of the blade 18 has a negative value. 3, P1 indicates the highest position of the cutting edge P0 of the blade 18. As shown in FIG. P2 indicates the lowest position of the cutting edge P0 of the blade 18 . The work machine 1 can lift the blade 18 between the highest position P1 and the lowest position P2.

Next, the control mode of the pitch angle of the blades 18 will be explained. The blade 18 pitch angle control mode includes an automatic mode and a manual mode. The controller 26 switches between automatic mode and manual mode according to the operation of the input device 32 . The operator can select between the automatic mode and the manual mode by operating the input device 32 .

In automatic mode, the controller 26 controls the pitch actuator 20 to change the pitch angle of the blade 18 according to the height of the blade 18 from the reference height H0. 4A-4C are diagrams showing the pitch angles of the blades 18. FIG. As shown in FIGS. 4A to 4C, the pitch angle θ1-θ3 of the blade 18 is the angle between the cutting edge P0 of the blade 18 and the ground plane G1 of the crawler belt 16. As shown in FIGS. FIG. 4B shows the pitch angle θ2 of the blade 18 in the standard state. FIG. 4A shows the pitch angle θ1 of the blade 18 tilted forward from the standard state. FIG. 4C shows the pitch angle θ3 of the blade 18 tilted more backward than the standard state. The pitch angle increases as the blade 18 tilts forward. The pitch angle decreases as the blade 18 tilts backward. That is, θ1>θ2>θ3.

The controller 26 stores pitch angle data. The pitch angle data defines the relationship between the height of the blades 18 and the target pitch angle of the blades 18 . The pitch angle data is stored in the controller 26 in the form of a map, for example. However, the pitch angle data may be stored in the controller 26 in other formats such as formulas, not limited to maps.

The controller 26 refers to the pitch angle data and determines the target pitch angle from the height of the blades 18 . The controller 26 controls the pitch actuator 20 so that the pitch angle of the blade 18 becomes the target pitch angle. FIG. 5 is a diagram showing an example of pitch angle data. The solid line in FIG. 5 indicates an example of pitch angle data in this embodiment.

In FIG. 5, the chain double-dashed line indicates changes in the pitch angle when the pitch angle control mode is not performed. That is, the chain double-dashed line in FIG. 5 indicates changes in the pitch angle when the pitch motion of the blade 18 is fixed (hereinafter referred to as the uncontrolled pitch angle). When the pitch motion is fixed, the pitch angle changes in proportion to the change in the height of the blade 18 between the maximum value Hmax and the minimum value Hmin, as indicated by the two-dot chain line in FIG. The change in pitch angle during non-control indicates the change in pitch angle due to the rotation of the lift frame 17 about the lift axis X1. When uncontrolled, the pitch angle decreases at a constant rate as the height of the blades 18 increases.

On the other hand, the pitch angle data in the automatic mode in this embodiment defines a target pitch angle larger than that in the non-controlled state for a blade 18 height greater than zero. Therefore, as shown in FIG. 6, the controller 26 controls the pitch actuator 20 to tilt the blade 18 forward more than when the blade 18 is not controlled when the blade 18 is positioned above the reference height H0. In FIG. 6, the two-dot chain line indicates the posture of the blade 18 when not controlled.

Further, as shown in FIG. 5, the absolute value of the inclination of the pitch angle data when the height of the blade 18 is in the first range (0-H1) is larger than when not controlled. The first range (0-H1) is the range of blade 18 heights from 0 to H1. H1 is a value between 0 and Hmax. The absolute value of the inclination of the pitch angle data when the height of the blade 18 is in the second range (H1-Hmax) is the same as when not controlled. The second range is the height of the blade 18 from H1 to Hmax.

When the height of the blade 18 is within the first range (0-H1), the controller 26 changes the pitch angle of the blade 18 in the direction of tilting the blade 18 forward according to the increase in the height of the blade 18. . Controller 26 fixes the pitch motion of blade 18 by pitch actuator 20 when the height of blade 18 is within the second range (H1-Hmax).

The pitch angle data in the automatic mode in this embodiment defines a target pitch angle that is smaller than that in the non-controlled state with respect to the height of the blade 18 that is smaller than zero. Therefore, as shown in FIG. 7, the controller 26 controls the pitch actuator 20 so that the blade 18 is tilted more backward than when not controlled when the blade 18 is positioned below the reference height H0. In FIG. 7, the two-dot chain line indicates the posture of the blade 18 when not controlled.

Also, as shown in FIG. 5, when the height of the blade 18 is within the third range (0-H2), the pitch angle decreases as the height of the blade 18 decreases. The third range (0-H2) is the range of blade 18 heights from 0 to H2. H2 is a value between 0 and Hmin. The absolute value of the inclination of the pitch angle data when the height of the blade 18 is in the fourth range (H2-Hmin) is the same as when not controlled. The fourth range (H2-Hmin) is the range from H2 to Hmin for the height of the blade 18 .

When the height of the blade 18 is within the third range (0-H2), the controller 26 changes the pitch angle of the blade 18 in the direction of tilting the blade 18 backward according to the decrease in the height of the blade 18. . The controller 26 fixes the pitch motion of the blade 18 by the pitch actuator 20 when the height of the blade 18 is within the fourth range (H2-Hmin).

In manual mode, the pitch actuator 20 is controlled so as to change the pitch angle of the blade 18 according to the operation of the operating device 31 . Also, when the operation device 31 is not operated, the pitch actuator 20 is controlled so as to maintain the pitch angle of the blade 18 . For example, when the operation device 31 is not operated, the controller 26 controls the pitch actuator 20 so as to maintain the pitch angle of the blades 18 even if some hydraulic oil leaks from the control valve 27 .

In the work machine 1 according to this embodiment described above, the pitch actuator 20 is automatically controlled to change the pitch angle of the blade 18 according to the height of the blade 18 in the automatic mode. Thereby, in the work machine 1, the pitch angle of the blade 18 can be adjusted easily and appropriately.

For example, when the blade 18 is positioned above the reference height H0, the pitch actuator 20 is controlled to tilt the blade 18 forward more than when not controlled. When the blade 18 is positioned above the reference height H0, ground leveling or soil removal work is often performed. Therefore, when the blade 18 is positioned above the reference height H0, the blade 18 tilts forward, thereby improving workability in leveling or discharging work.

Further, when the blade 18 is positioned below the reference height H0, the pitch actuator 20 is controlled to tilt the blade 18 more rearward than when not controlled. Excavation work is often performed when the blade 18 is positioned below the reference height H0. Therefore, when the blade 18 is positioned below the reference height H0, the blade 18 tilts backward, thereby improving workability in the excavation work.

As described above, in the working machine 1 according to the present embodiment described above, the automatic mode allows the pitch angle of the blade 18 to be easily and appropriately adjusted according to the work content.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the gist of the invention.

The working machine 1 is not limited to a bulldozer, and may be other vehicles such as a wheel loader and a motor grader. The controller 26 may have multiple controllers separate from each other. The processing by the controller 26 is not limited to the above embodiment, and may be modified. A part of the processing in the automatic mode or manual mode described above may be omitted. Alternatively, part of the processing described above may be changed.

The lift actuator 19 and the pitch actuator 20 are not limited to hydraulic cylinders. The lift actuator 19 and the pitch actuator 20 may be other actuators such as electric motors, for example. The pitch angle data are not limited to those in the above embodiment, and may be changed. For example, the pitch angle data may have a slope different from that during non-control even in the second range. Even in the fourth range, the pitch angle data may have an inclination different from that during non-control.

Advantageous Effects of Invention According to the present disclosure, it is possible to easily and appropriately adjust the pitch angle of a blade in a work machine.

11 Body 16 Track 17 Lift Frame 18 Blade 19 Lift Actuator 20 Pitch Actuator 26 Controller 31 Operating Device 33 Sensor

Claims (16)

a vehicle body;
a lift frame rotatably supported about the lift shaft with respect to the vehicle body;
a blade rotatably supported about the pitch axis with respect to the lift frame;
a lift actuator that is connected to the lift frame and the vehicle body and lifts the lift frame up and down about the lift axis;
a pitch actuator connected to the blade and the lift frame and pitching the blade about the pitch axis;
a sensor that detects the height of the blade from a reference height determined based on the vehicle body;
a controller that controls the pitch actuator to change the pitch angle of the blade according to the height of the blade;
A working machine with The controller controls the pitch actuator such that when the blade is positioned above the reference height, the blade is tilted more forward than when the pitch motion of the blade is fixed.
A work machine according to claim 1. When the blade is located above the reference height, the controller changes the pitch angle of the blade in a direction to tilt the blade forward according to the increase in the height of the blade. to control the actuator,
A work machine according to claim 2. The controller controls the pitch actuator to tilt the blade more rearward when the blade is positioned below the reference height than when the pitch motion of the blade is fixed.
A working machine according to any one of claims 1 to 3. When the blade is positioned below the reference height, the controller changes the pitch angle of the blade in a direction of tilting the blade backward in accordance with the decrease in the height of the blade. to control the actuator,
A working machine according to claim 4. The vehicle body includes crawler belts,
The reference height is the height of the contact surface of the crawler belt,
A working machine according to any one of claims 1 to 5. The controller is
storing pitch angle data that defines the relationship between the height of the blade and the target pitch angle of the blade;
determining the target pitch angle from the height of the blade with reference to the pitch angle data;
controlling the pitch actuator so that the pitch angle of the blade is the target pitch angle;
A working machine according to any one of claims 1 to 6. Further comprising an operating device for manually operating the pitch angle of the blade,
The controller is
Acquiring an operation signal indicating the operation of the operation device;
controlling the pitch actuator so as to change the pitch angle of the blade according to the operation of the operating device;
controlling the pitch actuator to maintain the pitch angle of the blade when the operating device is not operated;
A working machine according to any one of claims 1 to 7. a vehicle body; a lift frame rotatably supported with respect to the vehicle body about a lift axis; a blade rotatably supported with respect to the lift frame about a pitch axis; and a lift actuator connected to the lift frame for vertically lifting the lift frame about the lift axis; and a pitch actuator connected to the blade and the lift frame for pitching the blade about the pitch axis. A method for controlling a work machine comprising:
detecting the height of the blade from a reference height determined based on the vehicle body; controlling the pitch actuator to change the pitch angle of the blade according to the height of the blade;
How to prepare. further comprising controlling the pitch actuator to tilt the blade more forward when the blade is positioned above the reference height than when the pitch motion of the blade is fixed;
10. The method of claim 9. When the blade is located above the reference height, the pitch actuator is controlled so as to change the pitch angle of the blade in a direction of tilting the blade forward according to the increase in the height of the blade. be further prepared to
11. The method of claim 10. controlling the pitch actuator to tilt the blade more rearward when the blade is positioned below the reference height than when the pitch motion of the blade is fixed;
12. The method of any of claims 9-11, further comprising: When the blade is located below the reference height, the pitch actuator is controlled so as to change the pitch angle of the blade in a direction of tilting the blade backward in accordance with the decrease in the height of the blade. thing,
13. The method of claim 12, further comprising: The vehicle body includes crawler belts,
The reference height is the height of the contact surface of the crawler belt,
14. A method according to any of claims 9-13. Determining the target pitch angle from the height of the blade with reference to pitch angle data that defines the relationship between the height of the blade and the target pitch angle of the blade;
controlling the pitch actuator so that the pitch angle of the blade becomes the target pitch angle;
15. The method of any of claims 9-14, further comprising: obtaining an operation signal indicating operation of an operation device for manually operating the pitch angle of the blade;
controlling the pitch actuator so as to change the pitch angle of the blade according to the operation of the operating device;
controlling the pitch actuator to maintain the pitch angle of the blade when the operating device is not operated;
16. The method of any of claims 9-15, further comprising:

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