JP7522586B2 - Excavator - Google Patents

Description

This disclosure relates to a shovel.

For example, there is a known technology that relieves hydraulic oil in the bottom oil chamber of the boom cylinder when the attachment is operating to discharge soil and other materials stored in the bucket to the outside (hereinafter, "discharge operation") (see Patent Document 1).

This technology allows the pressure in the bottom oil chamber of the boom cylinder, which rises due to the retracting force of the rebound force of the extending force acting on the boom cylinder during the attachment ejection operation, to be released, suppressing the tipping moment acting on the machine body.

JP 2019-7175 A

However, while the above technology can suppress the dynamically generated tipping moment acting on the aircraft, as the boom moves downward, the overall center of gravity of the attachment moves away from the aircraft, which may reduce static stability.

In view of the above issues, the objective is to provide a technology that can further improve the stability of the shovel when discharging the attachment.

In order to achieve the above object, in one embodiment of the present disclosure,
A lower running body;
An upper rotating body rotatably mounted on the lower traveling body;
an attachment including a boom attached to the upper rotating body, an arm attached to a tip of the boom, and a bucket attached to a tip of the arm;
A boom cylinder that drives the boom;
a control valve that supplies hydraulic oil to the boom cylinder in accordance with an operation state of the boom,
When the attachment performs a discharge operation for discharging the contents of the bucket to the outside, the control valve is used to supply hydraulic oil only to the bottom side oil chamber of the bottom side oil chamber and the rod side oil chamber of the boom cylinder, regardless of the operation state of the boom.
Shovel provided.

The above-described embodiment provides a technology that can further improve the stability of the shovel during the attachment discharge operation.

FIG. 1 is a schematic diagram illustrating an example of an excavator management system. FIG. 1 is a diagram illustrating an example of a configuration of an excavator management system. FIG. 11 is a diagram illustrating another example of the configuration of the excavator management system. 1A and 1B are diagrams showing changes in behavior of a shovel (attachment) during a discharge operation of the shovel. FIG. 4 is a diagram showing the forces and moments acting on the boom cylinder and the machine body during the discharge operation of the shovel (attachment). FIG. 4 is a diagram showing the forces and moments acting on the boom cylinder and the machine body during the discharge operation of the shovel (attachment). FIG. 1 is a diagram showing a first example of a configuration for stabilizing the behavior of a shovel during a discharge operation. FIG. 13 is a diagram showing a second example of a configuration for stabilizing the behavior of a shovel during a discharge operation. 10 is a flowchart illustrating a first example of a control process related to stabilization of the behavior of a shovel during a discharge operation. 10 is a flowchart illustrating a second example of a control process related to stabilization of the behavior of a shovel during a discharge operation. 13 is a flowchart illustrating a third example of a control process related to stabilization of the behavior of a shovel during a discharge operation.

The following describes the embodiment with reference to the drawings.

[Outline of the excavator management system]
First, an overview of an excavator management system SYS according to this embodiment will be described with reference to FIG.

Figure 1 is a schematic diagram showing an example of an excavator management system SYS according to this embodiment.

As shown in FIG. 1, the excavator management system SYS includes an excavator 100 and a management device 200.

The excavator management system SYS may include one or more excavators 100. Similarly, the excavator management system SYS may include more than one management device 200. That is, the multiple management devices 200 may distribute and execute processing related to the excavator management system SYS. For example, each of the multiple management devices 200 may communicate with a portion of the multiple excavators 100 that it is responsible for, and execute processing targeted at that portion of the excavators 100.

The excavator management system SYS, for example, in the management device 200, collects information from the excavator 100 and monitors various conditions of the excavator 100 (e.g., the presence or absence of abnormalities in various devices mounted on the excavator 100, etc.).

The excavator management system SYS may also support remote operation of the excavator 100, for example, in the management device 200.

<Outline of the excavator>
As shown in Fig. 1, an excavator 100 according to this embodiment includes a lower traveling body 1, an upper rotating body 3 mounted on the lower traveling body 1 so as to be rotatable via a rotating mechanism 2, attachments including a boom 4, an arm 5, and a bucket 6, and a cabin 10 for an operator to ride in. Hereinafter, the front of the excavator 100 corresponds to the direction in which the attachments for the upper rotating body 3 extend when the excavator 100 is viewed in a plan view from directly above along the rotation axis of the upper rotating body 3 (hereinafter simply referred to as a "plan view"). In addition, the left and right sides of the excavator 100 correspond to the left and right sides, respectively, as viewed from the operator in the cabin 10.

The lower traveling body 1 includes, for example, a pair of left and right crawlers. The lower traveling body 1 allows the excavator 100 to travel by hydraulically driving each crawler by a left traveling hydraulic motor 1ML and a right traveling hydraulic motor 1MR (see FIG. 2).

The upper rotating body 3 rotates relative to the lower traveling body 1 as the rotating mechanism 2 is hydraulically driven by the rotating hydraulic motor 2A.

The boom 4 is attached to the front center of the upper rotating body 3 so that it can be raised and lowered, an arm 5 is attached to the tip of the boom 4 so that it can rotate up and down, and a bucket 6 is attached to the tip of the arm 5 so that it can rotate up and down.

The bucket 6 is an example of an end attachment. The bucket 6 is used, for example, for excavation work. In addition, instead of the bucket 6, another end attachment may be attached to the tip of the arm 5 depending on the work content, etc. The other end attachment may be, for example, another type of bucket, such as a slope bucket or a dredging bucket. The other end attachment may also be a type of end attachment other than a bucket, such as an agitator or a breaker.

The boom 4, arm 5, and bucket 6 are hydraulically driven by a boom cylinder 7, arm cylinder 8, and bucket cylinder 9, which serve as hydraulic actuators, respectively.

The cabin 10 is the cockpit where the operator sits and is mounted on the front left side of the upper rotating body 3.

The shovel 100 is equipped with a communication device 60 and can communicate with the management device 200 through a predetermined communication line NW (Network). This allows the shovel 100 to transmit (upload) various information to the management device 200 and receive various signals (e.g., information signals and control signals) from the management device 200. The communication line NW includes, for example, a wide area network (WAN). The wide area network may include, for example, a mobile communication network with a base station as its terminal. The wide area network may also include, for example, a satellite communication network that uses a communication satellite above the shovel 100. The wide area network may also include, for example, the Internet network. The communication line NW may also include, for example, a local network (LAN) of the facility where the management device 200 is installed. The local network may be a wireless line, a wired line, or a line including both. The communication line NW may also include a short-range communication line based on a specific wireless communication method such as Wi-Fi or Bluetooth (registered trademark).

The excavator 100 operates actuators (e.g., hydraulic actuators) in response to the operation of an operator in the cabin 10, and drives operating elements (hereinafter, "driven elements") such as the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6.

In addition to or instead of being configured to be operable by an operator in the cabin 10, the shovel 100 may be configured to be remotely operated from outside the shovel 100. When the shovel 100 is remotely operated, the inside of the cabin 10 may be unmanned. In the following description, it is assumed that the operation of the operator includes at least one of the operation of the operating device 26 by the operator in the cabin 10 and the remote operation by an external operator.

The remote operation includes, for example, an operation of the shovel 100 by input from a user (operator) regarding the actuator of the shovel 100 performed in a predetermined external device (for example, the management device 200). In this case, the shovel 100 transmits image information (hereinafter, "surrounding image") of the surroundings of the shovel 100 based on the output of the imaging device S6 described later to the external device, and the image information may be displayed on a display device (hereinafter, "display device for remote operation") provided in the external device. In addition, various information images (information screens) displayed on the output device 50 in the cabin 10 of the shovel 100 may also be displayed on the remote operation display device of the external device. This allows the operator of the external device to remotely operate the shovel 100 while checking the display contents, such as the surrounding image showing the state of the surroundings of the shovel 100 and various information images displayed on the display device for remote operation. Furthermore, the excavator 100 may operate actuators and drive driven elements such as the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6 in response to a remote control signal that is received from an external device and indicates the content of the remote control.

Remote operation may also include a mode in which the shovel 100 is operated by external voice input or gesture input to the shovel 100 by a person (e.g., a worker) around the shovel 100. Specifically, the shovel 100 recognizes voices uttered by surrounding workers and gestures made by the workers through an imaging device or a voice input device (e.g., a microphone) mounted on the shovel 100 (its own machine). The shovel 100 may then operate actuators in accordance with the contents of the recognized voices and gestures to drive driven elements such as the lower traveling body 1, upper rotating body 3, boom 4, arm 5, and bucket 6.

The excavator 100 may also automatically operate the actuators regardless of the content of the operator's operation. This allows the excavator 100 to realize a function (so-called "automatic driving function" or "machine control function") that automatically operates at least some of the driven elements such as the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6.

The automatic operation function may include a function for automatically operating a driven element (actuator) other than the driven element (actuator) to be operated in response to an operator's operation of the operating device 26 or remote operation (so-called "semi-automatic operation function" or "operation-assisted machine control function"). The automatic operation function may also include a function for automatically operating at least a part of the multiple driven elements (hydraulic actuators) on the assumption that there is no operation or remote operation of the operating device 26 by the operator (so-called "fully automatic operation function" or "fully automatic machine control function"). In the excavator 100, when the fully automatic operation function is enabled, the inside of the cabin 10 may be unmanned. The semi-automatic operation function, the fully automatic operation function, etc. may also include a mode in which the operation content of the driven element (actuator) to be the target of automatic operation is automatically determined according to a rule that is specified in advance. In addition, the semi-automatic operation function and the fully automatic operation function may include a mode in which the excavator 100 autonomously makes various decisions and autonomously determines the operation content of the driven element (hydraulic actuator) that is the target of the automatic operation based on the decision results (so-called "autonomous operation function").

<Overview of the management device>
The management device 200 manages the shovel 100, for example, the state of the shovel 100, the work being performed by the shovel 100, and the like.

The management device 200 may be, for example, a cloud server installed in a management center outside the work site where the shovel 100 works. The management device 200 may be, for example, an edge server installed in the work site where the shovel 100 works, or in a location relatively close to the work site (for example, a telecommunications carrier's office or base station). The management device 200 may be a stationary terminal device or a portable terminal device (mobile terminal) installed in a management office or the like in the work site of the shovel 100. The stationary terminal device may include, for example, a desktop computer terminal. The portable terminal device may include, for example, a smartphone, a tablet terminal, a laptop computer terminal, etc.

The management device 200 has, for example, a communication device 220 (see FIG. 2 and FIG. 3), and communicates with the shovel 100 through the communication line NW as described above. This allows the management device 200 to receive various information uploaded from the shovel 100 and transmit various signals to the shovel 100. Therefore, a user of the management device 200 can check various information related to the shovel 100 through the output device 240 (see FIG. 2 and FIG. 3). In addition, the management device 200 can transmit, for example, an information signal to the shovel 100 to provide information required for work, or transmit a control signal to control the shovel 100. The users of the management device 200 may include, for example, the owner of the shovel 100, the manager of the shovel 100, an engineer of the manufacturer of the shovel 100, the operator of the shovel 100, the manager, supervisor, worker, etc. of the work site of the shovel 100.

The management device 200 may also be configured to support remote operation of the shovel 100. For example, the management device 200 may have an input device (hereinafter, for convenience, "remote operation device") for an operator to perform remote operation, and a remote operation display device that displays image information (surrounding images) of the shovel 100 and the like. A signal input from the remote operation device is transmitted to the shovel 100 as a remote operation signal. This allows a user (operator) of the management device 200 to remotely operate the shovel 100 using the remote operation device while checking the surroundings of the shovel 100 on the remote operation display device.

[Excavator management system configuration]
Next, a specific configuration of the excavator management system SYS will be described with reference to Figs. 2 and 3 in addition to Fig. 1 .

Figures 2 and 3 are block diagrams showing an example and another example of the configuration of the excavator management system SYS according to this embodiment. In Figures 2 and 3, paths through which mechanical power is transmitted are shown by double lines, paths through which high-pressure hydraulic oil that drives hydraulic actuators flows are shown by solid lines, paths through which pilot pressure is transmitted are shown by dashed lines, and paths through which electrical signals are transmitted are shown by dotted lines. Figures 2 and 3 differ from each other only in the configuration of the excavator 100 out of the excavator 100 and the management device 200.

<Excavator configuration>
The shovel 100 includes various components, such as a hydraulic drive system for hydraulically driving the driven elements, an operation system for operating the driven elements, a user interface system for exchanging information with the user, a communication system for communicating with the outside, and a control system for various controls.

<<Hydraulic drive system>>
2 and 3 , the hydraulic drive system of the excavator 100 according to this embodiment includes hydraulic actuators that hydraulically drive each of the driven elements, such as the lower traveling body 1 (left and right crawlers), upper rotating body 3, boom 4, arm 5, and bucket 6, as described above. The hydraulic actuators include traveling hydraulic motors 1ML, 1MR, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, and bucket cylinder 9. The hydraulic drive system of the excavator 100 according to this embodiment also includes an engine 11, a regulator 13, a main pump 14, and a control valve 17.

The engine 11 is the main power source in the hydraulic drive system. The engine 11 is, for example, a diesel engine that uses light oil as fuel. The engine 11 is mounted, for example, at the rear of the upper rotating body 3. The engine 11 rotates at a constant speed at a preset target speed under direct or indirect control by the controller 30 (described later), and drives the main pump 14 and the pilot pump 15.

The regulator 13 controls (adjusts) the discharge volume of the main pump 14 under the control of the controller 30. For example, the regulator 13 adjusts the angle of the swash plate of the main pump 14 (hereinafter, the "tilt angle") in response to a control command from the controller 30.

The main pump 14 supplies hydraulic oil to the control valve 17 through a high-pressure hydraulic line. The main pump 14 is mounted, for example, at the rear of the upper rotating body 3, similar to the engine 11. As described above, the main pump 14 is driven by the engine 11. The main pump 14 is, for example, a variable displacement hydraulic pump, and as described above, under the control of the controller 30, the tilt angle of the swash plate is adjusted by the regulator 13 to adjust the stroke length of the piston and control the discharge flow rate (discharge pressure).

The control valve 17 is a hydraulic control device that controls the hydraulic actuators in response to the contents of the operator's operation of the operating device 26, the contents of remote operation, or operation commands related to the automatic operation function output from the controller 30. The control valve 17 is mounted, for example, in the center of the upper rotating body 3. As described above, the control valve 17 is connected to the main pump 14 via a high-pressure hydraulic line, and selectively supplies hydraulic oil supplied from the main pump 14 to the hydraulic actuators (travel hydraulic motors 1ML, 1MR, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, bucket cylinder 9, etc.) in response to the operating state of the operating device 26 or operation commands output from the controller 30. Specifically, the control valve 17 includes a plurality of control valves (also referred to as "directional control valves") 17A to 17F that control the flow rate and flow direction of the hydraulic oil supplied from the main pump 14 to each of the hydraulic actuators. Hereinafter, control valves 17A to 17F may be collectively referred to as "control valve 17X," or any one of control valves 17A to 17F may be individually referred to as "control valve 17X."

The control valve 17A is configured to supply hydraulic oil to the traveling hydraulic motor 1ML and to discharge the hydraulic oil from the traveling hydraulic motor and return it to the tank. This allows the control valve 17B to drive the traveling hydraulic motor 1ML in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the traveling hydraulic motor 1MR (i.e., the operation of the left crawler).

The control valve 17B is configured to supply hydraulic oil to the traveling hydraulic motor 1MR and to discharge the hydraulic oil from the traveling hydraulic motor and return it to the tank. This allows the control valve 17B to drive the traveling hydraulic motor 1MR in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the traveling hydraulic motor 1MR (i.e., the operation of the right crawler).

The control valve 17C is configured to supply hydraulic oil to the swing hydraulic motor 2A and to discharge the hydraulic oil from the swing hydraulic motor 2A and return it to the tank. This allows the control valve 17C to drive the swing hydraulic motor 2A in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the swing hydraulic motor 2A (i.e., the operation of the upper swing body 3).

The control valve 17D is configured to supply hydraulic oil to the boom cylinder 7 and to discharge the hydraulic oil from the boom cylinder 7 and return it to the tank. This allows the control valve 17D to drive the boom cylinder 7 in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the boom cylinder 7 (i.e., the operation of the boom 4).

The control valve 17E is configured to supply hydraulic oil to the arm cylinder 8 and to discharge the hydraulic oil from the arm cylinder 8 and return it to the tank. This allows the control valve 17E to drive the arm cylinder 8 in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the arm cylinder 8 (i.e., the operation of the arm 5).

The control valve 17F is configured to supply hydraulic oil to the bucket cylinder 9 and to discharge the hydraulic oil from the bucket cylinder 9 and return it to the tank. This allows the control valve 17F to drive the bucket cylinder 9 in response to the pilot pressure supplied from the hydraulic control valve 31 corresponding to the operation of the bucket cylinder 9 (i.e., the operation of the bucket 6).

The control valve 17X is, for example, a spool valve having two ports P1 and P2 to which pilot pressure is supplied (see, for example, the control valve 17D in Figures 7 and 8). The control valve 17X has a built-in spool that is movable in the axial direction, and the spool is biased toward the opposite end by spring members provided at both ends so as to balance the spool at a predetermined neutral position.

When hydraulic oil is supplied to port P1 of control valve 17X, the pressure (pilot pressure) acts on one axial end of the spool, causing the spool to move axially toward the other end with respect to the neutral position. As a result, as the spool moves, control valve 17X opens a path that supplies hydraulic oil to one of the two hydraulic oil supply and discharge ports of the hydraulic actuator and discharges hydraulic oil from the other, enabling the hydraulic actuator to be driven in one direction.

On the other hand, when hydraulic oil is supplied to port P2 of control valve 17X, the pressure (pilot pressure) acts on the other axial end of the spool, and the spool moves axially toward one end with respect to the neutral position. As a result, as the spool moves, control valve 17X opens a path that supplies hydraulic oil to the other of the two hydraulic oil supply and discharge ports of the hydraulic actuator and discharges hydraulic oil from one of them, enabling the hydraulic actuator to be driven in the other direction.

<<Operation system>>
2 and 3, the operation system of the shovel 100 according to this embodiment includes the pilot pump 15, the gate lock valve 25V, the operating device 26, and the hydraulic control valve 31. Furthermore, as shown in Fig. 2, the operation system of the shovel 100 according to this embodiment includes a shuttle valve 32 and a hydraulic control valve 33 when the operating device 26 is of the hydraulic pilot type.

The pilot pump 15 supplies pilot pressure to various hydraulic equipment via a pilot line 25. The pilot pump 15 is mounted, for example, at the rear of the upper rotating body 3, similar to the engine 11. The pilot pump 15 is, for example, a fixed displacement hydraulic pump, and is driven by the engine 11 as described above.

The gate lock valve 25V is provided in the pilot line 25 upstream of all the various hydraulic devices that receive hydraulic oil from the pilot pump 15. The gate lock valve 25V switches the pilot line 25 between communication and blocking (non-communication) by turning on/off a limit switch that is linked to the operation of the gate lock lever inside the cabin 10. Specifically, when the gate lock lever is raised, that is, when the cockpit is open, the limit switch is turned off, no voltage is applied from a power source (e.g., a battery) to the solenoid of the gate lock valve 25V, and the gate lock valve 25V is in a non-communication state. Therefore, the pilot line 25 is blocked and hydraulic oil is not supplied to the various hydraulic devices including the hydraulic control valve 31. On the other hand, when the gate lock lever is lowered, that is, when the cockpit is closed, the limit switch is turned on, voltage is applied from a power source to the solenoid of the gate lock valve 25V, and the gate lock valve 25V is in a communication state. As a result, the pilot line 25 is connected and hydraulic oil is supplied to various hydraulic equipment including the hydraulic control valve 31.

The operating device 26 is provided near the cockpit of the cabin 10 and is used by the operator to operate various driven elements (lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc.). In other words, the operating device 26 is used by the operator to operate hydraulic actuators (i.e., traveling hydraulic motors 1ML, 1MR, swing hydraulic motor 2A, boom cylinder 7, arm cylinder 8, bucket cylinder 9, etc.) that drive the respective driven elements. The operating device 26 includes, for example, lever devices that operate the boom 4 (boom cylinder 7), arm 5 (arm cylinder 8), bucket 6 (bucket cylinder 9), and upper rotating body 3 (swing hydraulic motor 2A). The operating device 26 also includes, for example, pedal devices or lever devices that operate the left and right crawlers (traveling hydraulic motors 1ML, 1MR) of the lower traveling body 1.

2, the operating device 26 is of a hydraulic pilot type. Specifically, the operating device 26 uses hydraulic oil supplied from the pilot pump 15 through the pilot line 25 and the pilot line 25A branched therefrom to output pilot pressure corresponding to the operation to the secondary pilot line 27A. The pilot line 27A is connected to one inlet port of the shuttle valve 32, and is connected to the control valve 17 via the pilot line 27 connected to the outlet port of the shuttle valve 32. This allows pilot pressure corresponding to the operation of various driven elements (hydraulic actuators) in the operating device 26 to be input to the control valve 17 via the shuttle valve 32. Therefore, the control valve 17 can drive each hydraulic actuator according to the operation of the operating device 26 by the operator, etc.

Also, for example, as shown in FIG. 3, the operating device 26 is electric. Specifically, the operating device 26 outputs an electric signal (hereinafter, "operation signal") according to the operation content, and the operation signal is input to the controller 30. The controller 30 then outputs a control command according to the content of the operation signal, that is, a control signal according to the operation content for the operating device 26, to the hydraulic control valve 31. As a result, a pilot pressure according to the operation content of the operating device 26 is input from the hydraulic control valve 31 to the control valve 17, and the control valve 17 can drive each hydraulic actuator according to the operation content of the operating device 26.

In addition, the control valves 17X (directional control valves) built into the control valve 17 and driving the respective hydraulic actuators may be of the electromagnetic solenoid type. In this case, the operation signal output from the operating device 26 may be input directly to the control valve 17, i.e., the electromagnetic solenoid type control valve 17X.

The hydraulic control valve 31 is provided for each driven element (hydraulic actuator) to be operated by the operating device 26. That is, the hydraulic control valve 31 is provided for each of the left crawler (travel hydraulic motor 1ML), the right crawler (travel hydraulic motor 1MR), the upper rotating body 3 (swing hydraulic motor 2A), the boom 4 (boom cylinder 7), the arm 5 (arm cylinder 8), and the bucket 6 (bucket cylinder 9). The hydraulic control valve 31 may be provided, for example, in the pilot line 25B between the pilot pump 15 and the control valve 17, and may be configured to change its flow area (i.e., the cross-sectional area through which the hydraulic oil can flow). As a result, the hydraulic control valve 31 can output a predetermined pilot pressure to the secondary pilot line 27B using the hydraulic oil of the pilot pump 15 supplied through the pilot line 25B. Therefore, as shown in FIG. 2, the hydraulic control valve 31 can indirectly apply a predetermined pilot pressure corresponding to a control signal from the controller 30 to the control valve 17 through the shuttle valve 32 between the pilot line 27B and the pilot line 27. Also, as shown in FIG. 3, the hydraulic control valve 31 can directly apply a predetermined pilot pressure to the control valve 17 in response to a control signal from the controller 30 through the pilot line 27B and the pilot line 27. Therefore, the controller 30 can supply a pilot pressure to the control valve 17 from the hydraulic control valve 31 in response to the operation of the electric operating device 26, thereby realizing the operation of the excavator 100 based on the operation of the operator.

The controller 30 may also control, for example, the hydraulic control valve 31 to realize the automatic driving function. Specifically, the controller 30 outputs a control signal corresponding to an operation command related to the automatic driving function to the hydraulic control valve 31, regardless of whether the operating device 26 is operated or not. This allows the controller 30 to supply pilot pressure corresponding to the operation command related to the automatic driving function from the hydraulic control valve 31 to the control valve 17, thereby realizing the operation of the excavator 100 based on the automatic driving function.

The controller 30 may also control, for example, the hydraulic control valve 31 to realize remote operation of the shovel 100. Specifically, the controller 30 outputs a control signal corresponding to the content of the remote operation specified by the remote operation signal received from the management device 200 to the hydraulic control valve 31 via the communication device 60 described below. As a result, the controller 30 can supply pilot pressure corresponding to the content of the remote operation from the hydraulic control valve 31 to the control valve 17, thereby realizing the operation of the shovel 100 based on the remote operation by the operator.

2, the shuttle valve 32 has two inlet ports and one outlet port, and outputs hydraulic oil having the higher pilot pressure of the two pilot pressures input to the inlet ports to the outlet port. The shuttle valve 32 is provided for each driven element (hydraulic actuator) to be operated by the operating device 26. That is, the shuttle valve 32 is provided for each of the left crawler (travel hydraulic motor 1ML), the right crawler (travel hydraulic motor 1MR), the upper rotating body 3 (swing hydraulic motor 2A), the boom 4 (boom cylinder 7), the arm 5 (arm cylinder 8), and the bucket 6 (bucket cylinder 9). One of the two inlet ports of the shuttle valve 32 is connected to the secondary pilot line 27A of the operating device 26 (specifically, the above-mentioned lever device or pedal device included in the operating device 26), and the other is connected to the secondary pilot line 27B of the hydraulic control valve 31. The outlet port of the shuttle valve 32 is connected to the pilot port of the corresponding control valve of the control valve 17 through the pilot line 27. The corresponding control valve is a control valve that drives a hydraulic actuator that is the object of operation of the above-mentioned lever device or pedal device connected to one inlet port of the shuttle valve 32. Therefore, each of these shuttle valves 32 can apply the higher of the pilot pressure of the pilot line 27A on the secondary side of the operating device 26 and the pilot pressure of the pilot line 27B on the secondary side of the hydraulic control valve 31 to the pilot port of the corresponding control valve. In other words, the controller 30 can control the corresponding control valve regardless of the operator's operation of the operating device 26 by outputting a pilot pressure higher than the pilot pressure on the secondary side of the operating device 26 from the hydraulic control valve 31. Therefore, the controller 30 can control the operation of the driven elements (lower traveling body 1, upper rotating body 3, attachment) regardless of the operating state of the operating device 26 by the operator, thereby realizing an automatic driving function.

2, the hydraulic control valve 33 is provided in the pilot line 27A connecting the operating device 26 and the shuttle valve 32. The hydraulic control valve 33 is configured to be able to change its flow path area, for example. The hydraulic control valve 33 operates in response to a control signal input from the controller 30. As a result, the controller 30 can forcibly reduce the pilot pressure output from the operating device 26 when the operating device 26 is operated by the operator. Therefore, even when the operating device 26 is operated, the controller 30 can forcibly suppress or stop the operation of the hydraulic actuator corresponding to the operation of the operating device 26. In addition, the controller 30 can reduce the pilot pressure output from the operating device 26 to be lower than the pilot pressure output from the hydraulic control valve 31, for example, even when the operating device 26 is operated. Therefore, the controller 30 can reliably apply a desired pilot pressure to the pilot port of the control valve in the control valve 17, for example, regardless of the operation content of the operating device 26, by controlling the hydraulic control valve 31 and the hydraulic control valve 33. Therefore, for example, the controller 30 can more appropriately realize the automatic operation function and remote control function of the excavator 100 by controlling the hydraulic control valve 33 in addition to the hydraulic control valve 31.

<<User Interface>>
As shown in FIGS. 2 and 3 , the user interface system of the shovel 100 according to this embodiment includes an operation device 26 , an output device 50 , and an input device 52 .

The output device 50 outputs various information to the user (operator) of the excavator 100 inside the cabin 10.

For example, the output device 50 includes indoor lighting equipment and display devices that are provided in a location that is easily visible to an operator seated in the cabin 10 and output various information in a visual manner. Examples of lighting equipment include warning lights. Examples of display devices include liquid crystal displays and organic electroluminescence (EL) displays.

In addition, for example, the output device 50 includes a sound output device that outputs various information by auditory means. Sound output devices include, for example, a buzzer and a speaker.

The input device 52 is installed within close proximity to the operator seated in the cabin 10 and receives various inputs from the operator, and signals corresponding to the received inputs are input to the controller 30.

For example, the input device 52 is an operation input device that accepts operation input. Operation input devices include a touch panel mounted on the display device, a touch pad installed around the display device, a button switch, a lever, a toggle, a knob switch provided on the operation device 26 (lever device), and the like.

For example, the input device 52 may be a voice input device that accepts voice input from an operator. The voice input device may include, for example, a microphone.

For example, the input device 52 may be a gesture input device that accepts gesture input from an operator. The gesture input device includes, for example, an imaging device (indoor camera) installed in the cabin 10.

<<Communications>>
As shown in FIGS. 2 and 3 , the communication system of the shovel 100 according to this embodiment includes a communication device 60.

The communication device 60 is connected to the communication line NW and communicates with a device (e.g., the management device 200) provided separately from the shovel 100. The device provided separately from the shovel 100 may include a device outside the shovel 100, as well as a portable terminal device brought into the cabin 10 by the user of the shovel 100. The communication device 60 may include, for example, a mobile communication module conforming to standards such as 4G ( ^4th Generation) and 5G ( ^5th Generation). The communication device 60 may also include, for example, a satellite communication module. The communication device 60 may also include, for example, a WiFi communication module, a Bluetooth communication module, or the like.

<<Control system>>
As shown in Figures 2 and 3, the control system of the shovel 100 according to this embodiment includes a controller 30. The control system of the shovel 100 according to this embodiment also includes a boom angle sensor S1, an arm angle sensor S2, a bucket angle sensor S3, a machine body inclination sensor S4, a turning state sensor S5, an imaging device S6, a boom cylinder pressure sensor S7, an arm cylinder pressure sensor S8, and a bucket cylinder pressure sensor S9. As shown in Figure 2, the control system of the shovel 100 according to this embodiment also includes an operating pressure sensor 29 when the operating device 26 is of a hydraulic pilot type.

The controller 30 performs various controls related to the excavator 100. The functions of the controller 30 may be realized by any hardware or any combination of hardware and software. For example, the controller 30 is configured around a computer including a CPU (Central Processing Unit), a memory device such as a RAM (Random Access Memory), a non-volatile auxiliary storage device such as a ROM (Read Only Memory), and various interface devices for input and output. The controller 30 realizes various functions, for example, by loading a program installed in the auxiliary storage device into the memory device and executing the program on the CPU.

The controller 30 controls the operation of the hydraulic actuator (driven element) of the excavator 100, for example, by controlling the hydraulic control valve 31.

Specifically, the controller 30 may control the operation of the hydraulic actuator (driven element) of the excavator 100 based on the operation of the operating device 26, with the hydraulic control valve 31 as the control object.

The controller 30 may also control the remote operation of the hydraulic actuator (driven element) of the shovel 100, with the hydraulic control valve 31 as the control target. That is, the operation of the hydraulic actuator (driven element) of the shovel 100 may include remote operation of the hydraulic actuator from outside the shovel 100.

The controller 30 may also control the automatic operation function of the shovel 100 by controlling the hydraulic control valve 31. That is, the operation of the hydraulic actuator of the shovel 100 may include an operation command for the hydraulic actuator of the shovel 100 that is output based on the automatic operation function.

The controller 30 also performs control related to, for example, stabilization of the behavior of the shovel 100 (hereinafter, "behavior stabilization"). The controller 30 includes a determination unit 301 and a stabilization control unit 302 as functional units related to the behavior stabilization of the shovel 100.

Note that some of the functions of the controller 30 may be realized by another controller (control device). In other words, the functions of the controller 30 may be realized in a distributed manner by multiple controllers.

As shown in FIG. 2, the operating pressure sensor 29 detects the pilot pressure on the secondary side (pilot line 27A) of the hydraulic pilot type operating device 26, i.e., the pilot pressure corresponding to the operating state of each driven element (hydraulic actuator) in the operating device 26. The detection signal of the pilot pressure by the operating pressure sensor 29 corresponding to the operating state of the lower traveling body 1, upper rotating body 3, boom 4, arm 5, bucket 6, etc. in the operating device 26 is input to the controller 30.

The boom angle sensor S1 acquires detection information regarding the attitude angle of the boom 4 (hereinafter, "boom angle") relative to a predetermined reference (e.g., a horizontal plane or one of the states at either end of the movable angle range of the boom 4). The boom angle sensor S1 may include, for example, a rotary encoder, an acceleration sensor, an angular velocity sensor, a six-axis sensor, an IMU (Inertial Measurement Unit), etc. The boom angle sensor S1 may also include a cylinder sensor capable of detecting the extension/retraction position of the boom cylinder 7.

The arm angle sensor S2 acquires detection information regarding the posture angle of the arm 5 (hereinafter, "arm angle") relative to a predetermined reference (e.g., a straight line connecting the connection points at both ends of the boom 4 or a state at either end of the movable angle range of the arm 5). The arm angle sensor S2 may include, for example, a rotary encoder, an acceleration sensor, an angular velocity sensor, a six-axis sensor, an IMU, etc. The arm angle sensor S2 may also include a cylinder sensor capable of detecting the extension/retraction position of the arm cylinder 8.

The bucket angle sensor S3 acquires detection information regarding the attitude angle of the bucket 6 (hereinafter, "bucket angle") relative to a predetermined reference (e.g., a straight line connecting the connection points at both ends of the arm 5 or a state at either end of the movable angle range of the bucket 6). The bucket angle sensor S3 may include, for example, a rotary encoder, an acceleration sensor, an angular velocity sensor, a six-axis sensor, an IMU, etc. The bucket angle sensor S3 may also include a cylinder sensor capable of detecting the extension/retraction position of the bucket cylinder 9.

The vehicle body tilt sensor S4 acquires detection information regarding the tilt state of the vehicle body including the lower running body 1 and the upper rotating body 3. The vehicle body tilt sensor S4 is mounted, for example, on the upper rotating body 3, and acquires detection information regarding the tilt angles of the upper rotating body 3 in the forward/backward and left/right directions (hereinafter, "forward/backward tilt angle" and "left/right tilt angle"). The vehicle body tilt sensor S4 may include, for example, an acceleration sensor (tilt sensor), an angular velocity sensor, a six-axis sensor, an IMU, etc.

The rotation state sensor S5 acquires detection information regarding the rotation state of the upper rotating body 3. The rotation state sensor S5 acquires detection information regarding the rotation angle of the upper rotating body 3 relative to a predetermined reference (e.g., a state in which the forward direction of the lower running body 1 and the front of the upper rotating body 3 are aligned). The rotation state sensor S5 includes, for example, a potentiometer, a rotary encoder, a resolver, etc.

Furthermore, if the components of the aircraft tilt sensor S4 (e.g., a six-axis sensor, an IMU, etc.) can acquire detection information regarding the attitude state of the upper rotating body 3, including not only the tilt angle of the upper rotating body 3 but also the rotation angle, the rotation state sensor S5 may be omitted.

For example, the shovel 100 may further be equipped with a positioning device capable of measuring the absolute position of the shovel itself. The positioning device may be, for example, a Global Navigation Satellite System (GNSS) sensor. This can improve the accuracy of estimating the attitude state of the shovel 100.

Furthermore, sensors S1 to S5 may be omitted. For example, information about the surroundings of the shovel 100 acquired by the imaging device S6 or a distance sensor described below may include information about the position and shape of surrounding objects and attachments as seen from the machine body (upper rotating body 3). In this case, for example, the controller 30 may be able to estimate the posture state of the shovel 100 from that information, depending on the required accuracy.

The imaging device S6 captures an image of the surroundings of the shovel 100 and outputs the captured image. The captured image output from the imaging device S6 is input to the controller 30.

The imaging device S6 includes, for example, a monocular camera, a stereo camera, a depth camera, etc. The imaging device may also acquire three-dimensional data (for example, point cloud data or surface data) representing the positions and shapes of objects around the shovel 100 within a predetermined imaging range (angle of view) based on the captured image.

In place of or in addition to the imaging device S6, the shovel 100 may be equipped with a distance sensor, such as a LIDAR (Light Detecting and Ranging), millimeter wave radar, ultrasonic sensor, infrared sensor, or distance image sensor. The distance sensor may acquire three-dimensional data representing the position and shape of objects around the shovel 100 within a predetermined detection range.

1, the imaging device S6 is attached to, for example, the front end of the upper surface of the cabin 10, and captures an image of the front of the upper rotating body 3 including the working range of the end attachment (bucket 6). This allows the controller 30 to recognize the situation in front of the shovel 100 based on the output of the imaging device S6. The controller 30 can also recognize the position of the shovel 100 and the rotation state of the upper rotating body 3 based on the position and changes in appearance of objects around the shovel 100 recognized from the output (captured image) of the imaging device S6. The imaging range of the imaging device S6 also includes the boom 4, arm 5, and end attachment (bucket 6), i.e., the attachment. This allows the controller 30 to recognize the attitude state of the attachment (for example, at least one attitude angle of the boom 4, arm 5, and bucket 6) based on the output of the imaging device S6. Therefore, when the shovel 100 is remotely operated, the controller 30 transmits the surrounding image based on the imaging device S6 and information on the recognition result to the management device 200, etc., and can provide an external operator with information on the shovel 100 (own machine) and its surroundings. Also, when the shovel 100 operates with a fully automatic driving function, a control device (for example, the controller 30) related to the fully automatic driving function can output an operation command related to the hydraulic actuator while grasping the surroundings of the shovel 100 and the attitude state of the own machine. Also, when the shovel 100 operates with a fully automatic driving function, the controller 30 transmits the surrounding image based on the imaging device S6 and information on the recognition result to the management device 200, etc., and can provide a user (monitor) who monitors the work from outside with information on the shovel 100 (own machine) and its surroundings.

The imaging device S6 may also be configured to be capable of acquiring an image of at least one of the left, right, and rear of the upper rotating body 3. This allows the controller 30 to recognize the situation not only in front of the shovel 100, but also to the left, right, and rear of the shovel 100.

The boom cylinder pressure sensor S7 detects the hydraulic pressure (cylinder pressure) of the boom cylinder 7. The boom cylinder pressure sensor S7 includes, for example, pressure sensors that detect the pressure in each of the bottom side oil chamber and the rod side oil chamber of the boom cylinder 7. The output (detection signal) of the boom cylinder pressure sensor S7 is input to the controller 30.

The arm cylinder pressure sensor S8 detects the hydraulic pressure (cylinder pressure) of the arm cylinder 8. The arm cylinder pressure sensor S8 includes, for example, pressure sensors that detect the pressure in each of the bottom side oil chamber and the rod side oil chamber of the arm cylinder 8. The output (detection signal) of the arm cylinder pressure sensor S8 is taken into the controller 30.

The bucket cylinder pressure sensor S9 detects the hydraulic pressure (cylinder pressure) of the bucket cylinder 9. The bucket cylinder pressure sensor S9 includes, for example, a pressure sensor that detects the pressure in each of the bottom side oil chamber and the rod side oil chamber of the bucket cylinder 9. The output (detection signal) of the bucket cylinder pressure sensor S9 is input to the controller 30.

The determination unit 301 determines whether the conditions for performing control related to stabilizing the behavior of the excavator 100 during the attachment discharge operation (hereinafter, "control execution conditions") are met.

The control execution conditions include "the attachment is performing a discharge operation" as a required condition (hereinafter, "control execution required condition"). In other words, the determination unit 301 determines whether the attachment is performing a discharge operation. The discharge operation of the attachment includes at least the operation of opening the bucket 6 from a substantially fully closed state. In addition, the discharge operation of the attachment may include the opening operation of the arm 5, which is performed together with the opening operation of the bucket 6.

The determination unit 301 may determine, for example, whether the attachment (boom 4, arm 5, and bucket 6) is performing a discharge operation based on the operation of the attachment. As described above, the operation of the attachment may include the operation of the operating device 26, remote operation, and an operation command based on an automatic driving function.

Specifically, the determination unit 301 may determine the content of the operation of the operation device 26 based on the output of the operation pressure sensor 29 or the operation signal. Furthermore, the determination unit 301 may determine the content of the remote operation based on a remote operation signal received from the management device 200 via the communication device 60. Furthermore, the determination unit 301 may obtain an operation command generated by a control device (e.g., controller 30) related to the autonomous driving function, and determine the content of the operation command.

The determination unit 301 may also determine the operation of the attachment based on the actual pilot pressure of the pilot line 27. The actual pilot pressure of the pilot line 27 is detected by a pressure sensor installed in the pilot line 27, and the detection signal is input to the controller 30.

The determination unit 301 may also determine whether the attachment is performing an ejection operation, for example, based on a change in the posture state of the attachment.

Specifically, the determination unit 301 may determine the posture state of the attachment and its changes based on the outputs of the boom angle sensor S1, the arm angle sensor S2, and the bucket angle sensor S3.

The determination unit 301 may also determine whether the attachment is performing a discharge operation based on the deviation between the static thrust of the boom 4 in the lifting direction (hereinafter, "static boom thrust") and the dynamic thrust of the boom 4 in the lifting direction (hereinafter, "dynamic boom thrust"). The static boom thrust is the thrust in the lifting direction of the boom 4 based on the force balance equation of the attachment, which is derived from the posture state of the attachment, the center of gravity and weight of the attachment, and the external forces acting on the attachment. The dynamic boom thrust is the thrust in the lifting direction of the boom 4 based on the actual value of the cylinder pressure of the boom cylinder 7 (the detection value of the boom cylinder pressure sensor S7).

Specifically, the determination unit 301 can determine that the attachment is performing a discharge operation when the dynamic boom thrust is significantly lower than the static boom thrust. When the attachment starts a discharge operation, as described below, a force acts on the boom cylinder 7 in the extension direction due to the opening movement of the bucket 6 and the arm 5, resulting in a relatively large drop in the pressure in the bottom oil chamber of the boom cylinder 7 (see Figures 4 and 5).

The determination unit 301 may also determine whether the attachment is performing an ejection operation by grasping the operating state of the attachment based on, for example, an image captured by the imaging device S6.

The control execution conditions may also include conditions (hereinafter, "control execution limiting conditions") for further limiting the situations in which control related to stabilizing the behavior of the excavator 100 is executed during the attachment discharge operation. Details of the control execution limiting conditions will be described later.

When the determination unit 301 determines that all of the control execution conditions are met, the stabilization control unit 302 performs control related to the stabilization of the behavior of the excavator 100. Details of the control related to the stabilization of the behavior of the excavator 100 will be described later.

<Configuration of Management Device>
As shown in FIG. 2, the management device 200 includes a control device 210 , a communication device 220 , an input device 230 , and an output device 240 .

The control device 210 performs various controls related to the management device 200. The functions of the control device 210 are realized by any hardware or any combination of hardware and software. The control device 210 is configured around a computer including, for example, a CPU, a memory device such as RAM, a non-volatile auxiliary storage device such as ROM, and various interface devices for input and output. The control device 210 realizes various functions by, for example, executing a program installed in the auxiliary storage device on the CPU.

For example, the control device 210 may acquire information received from the excavator 100 via the communication device 220, and perform processes such as constructing a database and performing specified processing to generate processing information.

For example, the control device 210 controls the remote operation of the shovel 100. The control device 210 may take in an input signal related to the remote operation of the shovel 100 received by the remote operation device, and use the communication device 220 to transmit to the shovel 100 a remote operation signal representing the content of the operation input, i.e., the content of the remote operation of the shovel 100.

The communication device 220 is connected to the communication line NW and communicates with the outside of the management device 200 (e.g., the excavator 100).

The input device 230 accepts input from an administrator or worker of the management device 200, and outputs a signal representing the content of the input (e.g., operation input, voice input, gesture input, etc.). The signal representing the content of the input is taken into the control device 210.

The input device 230 may include, for example, a remote control device. This allows the worker (operator) of the management device 200 to remotely operate the excavator 100 using the remote control device.

The output device 240 outputs various information to the user of the management device 200.

The output device 240 includes, for example, a lighting device or a display device that outputs various information to the user of the management device 200 in a visual manner. The lighting device includes, for example, a warning lamp, etc. The display device includes, for example, a liquid crystal display or an organic EL display, etc. The output device 240 also includes a sound output device that outputs various information to the user of the management device 200 in an auditory manner. The sound output device includes, for example, a buzzer, a speaker, etc.

The display device displays various information images related to the management device 200. The display device may include, for example, a remote operation display device, and the remote operation display device may display image information (surrounding images) of the surroundings of the shovel 100 uploaded from the shovel 100 under the control of the control device 210. This allows a user (operator) of the management device 200 to remotely operate the shovel 100 while checking the image information of the surroundings of the shovel 100 displayed on the remote operation display device.

[Shovel behavior when discharging attachment]
Next, the behavior of the shovel 100 during the attachment discharge operation will be described with reference to FIGS.

Figure 4 is a diagram showing the behavior of the excavator 100 during the discharge operation. Specifically, Figure 4 includes graphs 410 and 420 showing the time change in the cylinder pressure of the bottom oil chamber of the boom cylinder 7 and the pitching angle (rotation angle around the left-right axis of the upper rotating body 3) of the machine body (upper rotating body 3) during the discharge operation of the excavator 100. Figures 5 and 6 are diagrams showing the forces and moments acting on the boom cylinder 7 and the machine body, respectively, during the discharge operation of the excavator 100 to discharge the soil DT from the bucket 6 to the outside. Specifically, Figure 5 is a diagram showing the forces and moments acting on the boom cylinder 7 and the machine body, respectively, at the start of the discharge operation of the excavator 100 (at time t1 in Figure 4), and Figure 6 is a diagram showing the forces and moments acting on the boom cylinder 7 and the machine body, respectively, after the start of the discharge operation of the excavator 100 (at time t2 in Figure 4).

As shown in FIG. 5, when the attachment discharge operation is started, at least the bucket 6 moves in the opening direction. Therefore, the reaction force acts in the direction of raising the boom 4, and a force F1 in the extension direction acts on the rod of the boom cylinder 7. As a result, as shown in FIG. 4 (graph 410), from time t1 when the attachment discharge operation is started, the cylinder pressure in the bottom oil chamber of the boom cylinder 7 decreases, and the thrust of the boom 4 (dynamic boom thrust) decreases. In addition, a force moment M1 in the direction of tilting the excavator 100 backward acts on the body (upper rotating body 3) of the excavator 100 due to the force F1 in the extension direction acting on the boom cylinder 7.

After the attachment discharge operation starts, the hydraulic oil inside the boom cylinder 7 functions as a spring element against the displacement of the rod due to the force F1 in the extension direction acting on the boom cylinder 7 at the start. Therefore, as shown in FIG. 6, after the attachment discharge operation starts, the force F2 acts in the contraction direction due to the swing back of the force F1 acting in the extension direction at the start. As a result, as shown in FIG. 4 (graph 410), the cylinder pressure in the bottom oil chamber of the boom cylinder 7 reaches a minimum value between time t1 and time t2 after the attachment discharge operation starts, and then starts to rise. Then, at time t2, the cylinder pressure in the bottom oil chamber of the boom cylinder 7 reaches a maximum value that is somewhat higher than before the attachment discharge operation starts, and the thrust of the boom 4 (dynamic boom thrust) increases compared to before the discharge operation starts. In addition, a force moment M2 in the forward tilt direction acts on the machine body (upper rotating body 3) of the excavator 100 due to the force F2 in the contraction direction acting on the boom cylinder 7. As a result, as shown in FIG. 4 (graph 420), the pitching angle of the shovel 100's body changes in a forward tilt direction (a direction that lifts the rear part).

In this way, when the attachment is discharged, the force F1 due to the reaction force of the operation of the bucket 6, etc. and the swing back force F2 against the force F1 act on the boom cylinder 7. Therefore, the force F1 in the extension direction and the force F2 in the opposite contraction direction may excite vibrations, which may cause vibrations in the shovel 100 (machine body). In addition, the swing back force F2 may become excessive, or the amplitude of the vibration may be amplified, causing the force in the same contraction direction as the swing back force F2 (cylinder pressure in the bottom oil chamber of the boom cylinder 7) to become excessive, which may cause the shovel 100 to tip over forward. Therefore, in this embodiment, the controller 30 performs control related to the stabilization of the behavior of the shovel 100 during the attachment discharge operation, specifically, control to suppress a decrease in dynamic stability such as vibration or tipping of the shovel 100.

[Method of stabilizing excavator behavior]
Next, a specific example of a method for stabilizing the behavior of the attachment of the shovel 100 during a discharging operation will be described with reference to Figs.

<First example of a method for stabilizing the behavior of an excavator>
FIG. 7 is a diagram showing a first example of a configuration for stabilizing the behavior of the shovel 100 during a discharge operation.

As shown in FIG. 7, the control valve 17D is a spool valve that can move axially toward both ends based on a predetermined neutral position by the pilot pressure of the hydraulic oil supplied through the pilot line 27.

Control valve 17D includes pilot ports P1 and P2.

The control valve 17D is biased by elastic bodies (e.g., springs) from both axial ends so as to balance at a predetermined axial neutral position when hydraulic oil (pilot pressure) is not supplied to either pilot port P1 or P2. When the spool is in the neutral position, the control valve 17D opens the center bypass oil passage that circulates hydraulic oil between the main pump 14 and the tank, and blocks the oil passage between the main pump 14 and the boom cylinder 7 and the oil passage between the boom cylinder 7 and the tank.

The pilot port P1 is provided at one axial end of the control valve 17D (the left end in the figure) and is connected to a pilot line 27 that corresponds to the operation of the boom cylinder 7 in the extension direction (the direction in which the boom 4 is raised). As a result, the hydraulic oil supplied to the pilot port P1 causes the control valve 17D to move the spool to the other end side based on the neutral position, and supply hydraulic oil to the bottom side oil chamber of the boom cylinder 7 and discharge hydraulic oil from the rod side oil chamber to the tank according to the operating state of the boom 4 (boom cylinder 7).

The pilot port P2 is provided at the other axial end of the control valve 17D (the right end in the figure) and is connected to a pilot line 27 that corresponds to the operation of the boom cylinder 7 in the retracting direction (the direction in which the boom 4 is lowered). As a result, the hydraulic oil supplied to the pilot port P2 causes the control valve 17D to move the spool to one end side based on the neutral position, and supply hydraulic oil to the rod side oil chamber of the boom cylinder 7 and discharge hydraulic oil from the bottom side oil chamber to the tank according to the operating state of the boom 4 (boom cylinder 7).

Also, as shown in FIG. 7, in this example, the hydraulic control system of the excavator 100 includes a control valve 70.

The control valve 70 can supply hydraulic oil discharged from the main pump 14 to the rod-side oil chamber of the boom cylinder 7, and discharge hydraulic oil from the rod-side oil chamber to the tank.

The control valve 70 includes two electromagnetic solenoids S1 and S2.

The control valve 70 is biased from both axial ends by elastic bodies (e.g., springs) so that it is balanced at a predetermined axial neutral position when no control current is applied to either of the electromagnetic solenoids S1 and S2. When the spool is in the neutral position, the control valve 70 cuts off the hydraulic oil path between the main pump 14 and the boom cylinder 7, and also cuts off the hydraulic oil path between the rod side oil chamber of the boom cylinder 7 and the tank.

The electromagnetic solenoid S1 is provided at one end in the axial direction (the left end in the figure) and is configured to expand and contract in response to a control current applied from the controller 30, so that the spool can be moved in the axial direction from one end to the other end (the right end in the figure) based on the neutral position.

When the spool moves from one end to the other end with respect to the neutral position due to the control current applied to the electromagnetic solenoid S1, the control valve 70 opens the path between the main pump 14 and the boom cylinder 7. The control valve 70 then supplies hydraulic oil to the rod side oil chamber of the boom cylinder 7 at a flow rate according to its opening.

The electromagnetic solenoid S2 is provided at the other end in the axial direction and expands in response to a control current applied from the controller 30, and is configured to be able to move the spool in the axial direction from the other end to one end, based on the neutral position.

When the spool moves from the other end to one end with respect to the neutral position as a reference due to the control current applied to the electromagnetic solenoid S2, the control valve 70 opens the path between the rod side oil chamber of the boom cylinder 7 and the tank. Then, the control valve 70 discharges hydraulic oil from the rod side oil chamber of the boom cylinder 7 to the tank at a flow rate according to its opening degree.

In addition, the control valve 70 may be configured such that the spool moves with hydraulic oil supplied to pilot ports at both ends in the axial direction, as in the case of the control valve 17D. In this case, the two pilot ports of the control valve 70 may be connected to two hydraulic control valves (e.g., proportional valves) that use hydraulic oil supplied from the pilot pump 15 to output hydraulic oil at a pilot pressure according to the control current from the controller 30.

When the control execution condition is satisfied, the stabilization control unit 302 outputs a control command (control current) to the electromagnetic solenoid S1. This allows the controller 30 to use the control valve 70 to supply hydraulic oil to the rod-side oil chamber of the boom cylinder 7 while retaining hydraulic oil in the bottom-side oil chamber of the boom cylinder 7. Therefore, the boom cylinder 7 is subjected to the force F1 in the extension direction acting on the rod when the attachment discharge operation begins, and the force DG in the opposing direction, thereby suppressing the movement of the piston rod (boom 4) of the boom cylinder 7. Therefore, the controller 30 can suppress the generation of the force F2 that swings back against the force F1, and suppress the decrease in the dynamic stability of the excavator 100, i.e., the vibration and forward tipping of the excavator 100, etc.

The flow rate of the hydraulic oil supplied from the control valve 70 to the rod side oil chamber of the boom cylinder 7 may be controlled, for example, taking into consideration the load state of the boom cylinder 7, that is, the weight of the contents stored in the bucket 6 at the start of the discharge operation. This is because the greater the weight of the contents of the bucket 6, the greater the reaction force acting on the boom 4 due to the opening operation of the bucket 6 etc. at the start of the discharge operation of the attachment. That is, the stabilization control unit 302 may determine the control command value (control current value) taking into consideration the weight of the contents stored in the bucket 6 at the start of the discharge operation. In this case, the stabilization control unit 302 may measure (estimate) the weight of the contents stored in the bucket 6, for example, based on the pressure in the bottom side oil chamber of the boom cylinder 7 immediately before the start of the discharge operation of the attachment. The stabilization control unit 302 may also recognize the contents of the bucket 6 based on the image captured by the imaging device S6 and estimate its weight.

The flow rate of hydraulic oil supplied from the control valve 70 to the rod side oil chamber of the boom cylinder 7 may be controlled, for example, taking into consideration the speed and acceleration of the opening operation of the bucket 6 and the arm 5. This is because the greater the speed and acceleration of the bucket 6 and the arm 5, the greater the reaction force acting on the boom 4 due to the opening operation of the bucket 6, etc. at the start of the attachment discharge operation. That is, the stabilization control unit 302 may determine the control command value (control current value) to be supplied to the electromagnetic solenoid S1 of the control valve 70, taking into consideration the speed and acceleration of the opening operation of the bucket 6 and the arm 5. In this case, the stabilization control unit 302 may obtain the speed and acceleration of the arm 5 and the bucket 6, for example, based on the output of the arm angle sensor S2 and the bucket angle sensor S3. The stabilization control unit 302 may also estimate the speed and acceleration of the arm 5 and the bucket 6 based on the output of the arm angle sensor S2 and the bucket angle sensor S3 based on the operation content (operation amount) of the arm 5 and the bucket 6.

<Second example of a method for stabilizing the behavior of an excavator>
FIG. 8 is a diagram showing a second example of a configuration for stabilizing the behavior of the shovel 100 during a discharge operation.

As shown in FIG. 8, in this example, when the control execution condition is satisfied, the stabilization control unit 302 outputs a control command (control current) to the hydraulic control valve 31 corresponding to the operation of the boom cylinder 7 in the extension direction, and supplies hydraulic oil to the pilot port P1 of the control valve 17D. As a result, the controller 30 can use the control valve 17D to supply hydraulic oil to the bottom side oil chamber of the boom cylinder 7 and discharge the hydraulic oil in the rod side oil chamber to the tank during the attachment discharge operation. Therefore, the controller 30 can actively move the boom cylinder 7 in the same direction as the extension direction F1 acting on the rod with the start of the attachment discharge operation, and suppress the generation of the swing back force F2. Therefore, the controller 30 can suppress the decrease in the dynamic stability of the excavator 100, that is, the vibration and forward tipping of the excavator 100.

The flow rate of hydraulic oil supplied from the control valve 17D to the bottom oil chamber of the boom cylinder 7 may be controlled, for example, in the same manner as in the first example described above, taking into consideration the load state of the boom cylinder 7, i.e., the weight of the contents contained in the bucket 6 at the start of the discharge operation. That is, the stabilization control unit 302 may determine the control command value (control current value) to the hydraulic control valve 31 taking into consideration the weight of the contents contained in the bucket 6 at the start of the discharge operation.

The flow rate of hydraulic oil supplied from the control valve 17D to the bottom oil chamber of the boom cylinder 7 may be controlled, for example, in consideration of the speed and acceleration of the opening movement of the bucket 6 and the arm 5, as in the first example described above. That is, the stabilization control unit 302 may determine the control command value (control current value) to be supplied to the hydraulic control valve 31 in consideration of the speed and acceleration of the opening movement of the bucket 6 and the arm 5.

[Control method for stabilizing the behavior of an excavator]
Next, a specific example of a control process for stabilizing the behavior of the shovel 100 during a discharge operation will be described with reference to FIGS.

<First example of control method>
Fig. 9 is a flowchart outlining a first example of a control process related to stabilization of the behavior during a discharge operation of the shovel 100. The process of this flowchart is repeatedly executed at predetermined control periods while the shovel 100 is in operation, that is, from start-up (e.g., key switch ON) to stop (e.g., key switch OFF) of the shovel 100. The same may be applied to the processes of the flowcharts of Figs. 10 and 11 below.

As shown in FIG. 9, in step S102, the determination unit 301 determines whether the attachment is performing an ejection operation. That is, the determination unit 301 determines whether the control execution prerequisite conditions are met. If the attachment has started an ejection operation, the determination unit 301 proceeds to step S104; otherwise, the determination unit 301 ends this flow chart.

In step S104, the stabilization control unit 302 calculates a control command value for stabilizing the behavior. In the case of FIG. 7 (first example) above, the stabilization control unit 302 calculates a control command value (control current value) to the control valve 70 (electromagnetic solenoid S1), and in the case of FIG. 8 (second example) above, the stabilization control unit 302 calculates a control command value (control current value) to the hydraulic control valve 31 corresponding to the pilot port P1 of the control valve 17D.

When the processing of step S104 is completed, the controller 30 proceeds to step S106.

In step S106, the stabilization control unit 302 outputs a control command to the control valve 70 or the control valve 70 corresponding to the pilot port P1 of the control valve 17D based on the calculation result of step S104. This enables the controller 30 to supply hydraulic oil to the boom cylinder 7 through the control valve 70 or the control valve 17D so as to suppress the swing back force F2.

When the processing of step S106 is completed, the controller 30 ends the processing of this flowchart.

In this way, in this example, when the attachment is discharged, the controller 30 supplies hydraulic oil to the boom cylinder 7 regardless of the operation state of the boom 4, thereby suppressing a decrease in the dynamic stability of the excavator 100 (e.g., vibration or tipping forward).

<Second example of control method>
FIG. 10 is a flowchart illustrating a second example of a control process related to stabilizing the behavior of the shovel 100 during a discharge operation.

As shown in FIG. 10, step S202 is the same as the processing in step S102 in FIG. 9, so the explanation is omitted.

When the processing of step S202 is completed, the controller 30 proceeds to step S204.

In step S204, the determination unit 301 determines whether or not the boom 4 is being operated. That is, the determination unit 301 determines whether or not the control execution limiting condition "the boom 4 is not being operated" is satisfied. If the boom 4 is not being operated, the determination unit 301 proceeds to step S206, and if the boom 4 is being operated, the determination unit 301 ends the processing of this flowchart.

The processing in steps S206 and S208 is the same as steps S104 and S106 in FIG. 9, so a description thereof will be omitted.

When the processing of step S208 is completed, the controller 30 ends the processing of this flowchart.

In this way, in this example, when the attachment discharge operation is being performed, the controller 30 can supply hydraulic oil to the boom cylinder 7 only when the boom 4 (boom cylinder 7) is not being operated. This makes it possible to prevent, for example, a situation in which the boom 4 performs an operation different from the operation performed by the operator while the operator is operating the boom 4, causing the operator to feel uncomfortable. Therefore, in this example, it is possible to prevent a decrease in dynamic stability during the discharge operation of the excavator 100 while suppressing any sense of discomfort felt by the operator.

<Third example of control method>
FIG. 11 is a flowchart illustrating a third example of a control process related to stabilizing the behavior of the shovel 100 during a discharge operation.

As shown in FIG. 11, step S302 is the same as the processing in step S102 in FIG. 9, so the explanation is omitted.

When the processing of step S302 is completed, the controller 30 proceeds to step S304.

In step S304, the determination unit 301 determines whether or not there is a high possibility that the shovel 100 (machine) will vibrate or tip over. That is, the determination unit 301 determines whether or not the control execution limiting condition "is in a state in which there is a high possibility that the dynamic stability of the shovel 100 (machine) will decrease" is satisfied.

States in which the dynamic stability of the excavator 100 (machine) is likely to decrease include, for example, a state in which the bucket 6 contains more than a predetermined standard of contents, in other words, a state in which the load on the attachment exceeds a predetermined standard. This is because the heavier the contents, such as soil and sand, contained in the bucket 6, the greater the reaction force acting on the boom 4 due to the discharge operation of the attachment (opening operation of the bucket 6, etc.). The predetermined standard may be, for example, greater than zero or may be zero. In the latter case, the determination unit 301 determines that the control execution limiting condition is met if the bucket 6 contains even a small amount of contents.

In addition, conditions in which the dynamic stability of the excavator 100 (machine) is likely to decrease include, for example, conditions in which the speed or acceleration of the bucket 6 or arm 5 is relatively high (specifically, greater than a predetermined standard). As described above, the higher the speed or acceleration of the opening movement of the bucket 6 or arm 5, the greater the reaction force acting on the boom 4 due to the discharge movement of the attachment (opening movement of the bucket 6, etc.).

If the shovel 100 (machine) is in a state where there is a high possibility of vibration or tipping over, i.e., where there is a high possibility of a relative decrease in dynamic stability, the determination unit 301 proceeds to step S306; otherwise, the determination unit 301 proceeds to step S308.

Steps S306 and S308 are the same as steps S104 and S106 in FIG. 9, so their explanation is omitted.

When the processing of step S308 is completed, the controller 30 ends the processing of this flowchart.

In this way, in this example, when the attachment discharge operation is being performed, the controller 30 can supply hydraulic oil to the boom cylinder 7 only when there is a high possibility that the dynamic stability of the shovel 100 (machine) will decrease relatively. This makes it possible to prevent a situation in which the boom 4 operates without being operated, causing discomfort to the operator, for example, in a situation in which there is no contents in the bucket 6 and the shovel 100 (machine) is unlikely to vibrate or tip over. Therefore, in this example, it is possible to prevent a decrease in dynamic stability during the discharge operation of the shovel 100 while suppressing discomfort to the operator.

<Other examples of control methods>
The above second and third examples may be combined.

Specifically, the stabilization control unit 302 may be configured to perform processing equivalent to steps S206 and S208 (steps S306 and S308) when both of the control execution limiting conditions corresponding to step S204 in FIG. 10 and step S304 in FIG. 11 are satisfied. In this case, a determination process similar to step S304 may be inserted between step S202 and step S204, or between step S204 and step S206.

As a result, in this example, the shovel 100 achieves the functions and effects of both the second and third examples described above.

[Action]
Next, the operation of the shovel 100 according to this embodiment will be described.

In this embodiment, the excavator 100 includes a lower traveling body 1, an upper rotating body 3 mounted on the lower traveling body so as to be freely rotatable, a boom 4 attached to the upper rotating body 3, an arm 5 attached to the tip of the boom 4, and an attachment including a bucket attached to the tip of the arm 5, and a boom cylinder 7 that drives the boom 4. When the attachment performs a discharge operation to discharge contents of the bucket 6 to the outside, the excavator 100 supplies hydraulic oil to the boom cylinder 7 regardless of the operating state of the boom 4.

For example, when the attachment performs a discharge operation, the reaction force from the opening operation of the arm 5 and bucket 6 acts on the boom cylinder 7 in the extension direction, reducing the load, but then the return swing acts on the boom cylinder 7 in the contraction direction, increasing the load. As a result, the increase or decrease in the load (pressure) on the boom cylinder causes the hydraulic oil inside the boom cylinder 7 to act as a spring element, causing the entire attachment to vibrate, which could cause the machine to vibrate or tip over.

In contrast, in this embodiment, when the attachment performs a discharge operation, the shovel 100 can supply hydraulic oil to the boom cylinder 7 regardless of the operation state of the boom 4. Therefore, the shovel 100 can suppress an increase or decrease in the load (pressure) of the boom cylinder 7 by the hydraulic oil supplied to the boom cylinder 7, and suppress vibration and tipping of the shovel 100. This improves the dynamic stability of the shovel 100.

In addition, in this embodiment, the shovel 100 supplies hydraulic oil to the boom cylinder 7 to improve dynamic stability. Therefore, the shovel 100 can suppress the downward movement of the boom 4 under its own weight, for example, by discharging the hydraulic oil in the boom cylinder 7 to the outside and suppressing the function of the hydraulic oil as a spring element. This can further improve the static stability and safety of the shovel 100.

In addition, in this embodiment, when the attachment performs a discharge operation, the excavator 100 may supply hydraulic oil to the boom cylinder 7 so as to suppress the swing back motion of the boom cylinder 7 in the retracting direction caused by the force acting on the boom cylinder 7 in the extending direction due to the discharge operation of the attachment.

As a result, the excavator 100 can suppress the swing back motion of the boom cylinder 7 in the retracting direction, thereby suppressing the increase or decrease in the load on the boom cylinder 7 that can cause a decrease in the dynamic stability of the excavator 100 (e.g., the occurrence of vibration or tipping over).

In addition, in this embodiment, when the attachment performs a discharge operation, the excavator 100 may supply hydraulic oil to the bottom-side oil chamber of the boom cylinder 7 and discharge hydraulic oil from the rod-side oil chamber of the boom cylinder 7, thereby moving the boom 4 in the lifting direction.

As a result, the excavator 100 can supply and discharge hydraulic oil to and from the boom cylinder 7 in synchronization with the force in the extension direction acting on the boom cylinder 7 as a reaction force to the movement of the arm 5 and bucket 6 during the discharge operation, and move the boom 4 in the lifting direction. Therefore, the excavator 100 can suppress the swing back movement of the boom cylinder 7 in the retracting direction, and suppress fluctuations in the load (pressure) of the boom cylinder 7 that are a factor in reducing the dynamic stability of the excavator 100.

In addition, in this embodiment, when the attachment performs a discharge operation, the excavator 100 may supply hydraulic oil to the rod-side oil chamber while retaining hydraulic oil in the bottom-side oil chamber of the boom cylinder 7, thereby suppressing the movement of the boom 4 in the upward direction caused by the force in the extension direction.

As a result, the excavator 100 can supply hydraulic oil only to the rod-side oil chamber of the boom cylinder 7, and apply to the boom cylinder 7 a reaction force that counteracts the force in the extension direction that acts on the boom cylinder 7 as a reaction force to the movement of the arm 5 and bucket 6 during the discharge operation. Therefore, the excavator 100 can suppress the movement of the boom cylinder 7 at the start of the discharge operation of the attachment, and as a result, can suppress the swing back movement of the boom cylinder 7 in the retraction direction. Therefore, the excavator 100 can suppress fluctuations in the load (pressure) of the boom cylinder 7, which are a factor in reducing the dynamic stability of the excavator itself (the excavator 100).

In addition, in this embodiment, the excavator 100 may supply hydraulic oil to the boom cylinder 7 when the boom 4 is not being operated and the attachment is performing a discharge operation.

This allows the excavator 100 to supply hydraulic oil to the boom cylinder 7 in association with the attachment discharge operation only when the boom 4 is not being operated. Therefore, the excavator 100 can prioritize the operation of the boom 4 when the boom 4 is being operated, and can realize the operation of the boom 4 in accordance with the operation, while suppressing a decrease in the dynamic stability of the excavator 100.

In addition, in this embodiment, the shovel 100 may supply hydraulic oil to the boom cylinder 7 when the attachment is performing a discharge operation in a state in which the dynamic stability of the shovel 100 itself (the shovel 100) is relatively likely to decrease.

This allows the shovel 100 to supply hydraulic oil to the boom cylinder 7 in association with the attachment discharge operation only in situations where there is a high possibility of the shovel 100 actually vibrating or tipping over. Therefore, the shovel 100 can suppress a decrease in the dynamic stability of the shovel 100 itself in association with the attachment discharge operation, while suppressing any discomfort felt by the operator due to hydraulic oil being supplied to the boom cylinder 7 regardless of operation.

In addition, in this embodiment, a state in which the dynamic stability of the shovel 100 is relatively likely to decrease may include a state in which the bucket 6 contains more than a predetermined amount of content.

This allows the excavator 100 to supply hydraulic oil to the boom cylinder 7 in a situation where a large amount of soil or other material is contained in the bucket 6 and the reaction force of the arm 5 and bucket 6 associated with the attachment discharge operation tends to be relatively large. Therefore, the excavator 100 can suppress a decrease in dynamic stability (e.g., vibration or tipping of the machine body) according to the specific situation.

In addition, in this embodiment, a state in which the dynamic stability of the shovel 100 is relatively likely to decrease may include a state in which the speed or acceleration of at least one of the arm 5 and the bucket 6 is relatively high.

This allows the excavator 100 to supply hydraulic oil to the boom cylinder 7 in a situation where the speed and acceleration of the arm 5 and bucket 6 during the attachment discharge operation are relatively high and the reaction force of the operation of the arm 5 and bucket 6 tends to be relatively large. Therefore, the excavator 100 can suppress a decrease in dynamic stability according to the specific situation.

In addition, in this embodiment, when the attachment performs a discharge operation, the excavator 100 may supply hydraulic oil to the boom cylinder 7 at a flow rate that corresponds to the acceleration of the boom 4, the acceleration of the arm 5, and the load state of the attachment due to the contents of the bucket 6.

This allows the excavator 100 to supply hydraulic oil at an appropriate flow rate to suppress fluctuations in the load (pressure) of the boom cylinder 7 according to the acceleration of the arm 5 and bucket 6 during the attachment discharge operation and the load state of the attachment due to the contents of the bucket 6.

[Transformations/Changes]
Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist described in the claims.

For example, in the above-described embodiment, the excavator 100 is configured such that all of the driven elements, such as the lower traveling body 1, the upper rotating body 3, the boom 4, the arm 5, and the bucket 6, are hydraulically driven, but some or all of them may be electrically driven by an electric actuator. In other words, the configurations disclosed in the above-described embodiment may be applied to hybrid excavators, electric excavators, etc.

LIST OF SYMBOLS 1 Lower traveling body 1ML, 1MR Travel hydraulic motor 2A Swing hydraulic motor 3 Upper rotating body 4 Boom 5 Arm 6 Bucket 7 Boom cylinder 8 Arm cylinder 9 Bucket cylinder 10 Cabin 11 Engine 13 Regulator 14 Main pump 15 Pilot pump 17 Control valve 17A to 17F Control valve 25, 25A, 25B, 27, 27A, 27B Pilot line 25V Gate lock valve 30 Controller 31 Hydraulic control valve 33 Hydraulic control valve 50 Output device 52 Input device 60 Communication device 70 Control valve 100 Excavator 200 Management device 301 Determination unit 302 Stabilization control unit S1 Boom angle sensor S2 Arm angle sensor S3 Bucket angle sensor S4 Machine body inclination sensor S5 Swing state sensor S6 Imaging device S7 Boom cylinder pressure sensor S8 Arm cylinder pressure sensor S9 Bucket cylinder pressure sensor

Claims (8)

A lower running body;
An upper rotating body rotatably mounted on the lower traveling body;
an attachment including a boom attached to the upper rotating body, an arm attached to a tip of the boom, and a bucket attached to a tip of the arm;
A boom cylinder that drives the boom;
a control valve that supplies hydraulic oil to the boom cylinder in accordance with an operation state of the boom,
When the attachment performs a discharge operation for discharging the contents of the bucket to the outside, the control valve is used to supply hydraulic oil only to the bottom side oil chamber of the bottom side oil chamber and the rod side oil chamber of the boom cylinder, regardless of the operation state of the boom.
Shovel. When the attachment performs the discharge operation, hydraulic oil is supplied to the boom cylinder using the control valve so as to suppress a swing back operation of the boom cylinder in a contraction direction caused by a force in an extension direction acting on the boom cylinder due to the discharge operation of the attachment.
The shovel according to claim 1. When the attachment performs the discharge operation, the control valve is used to supply hydraulic oil to a bottom side oil chamber of the boom cylinder and to discharge hydraulic oil from a rod side oil chamber of the boom cylinder, thereby moving the boom in a lifting direction.
The shovel according to claim 1 or 2. When the attachment is performing the discharge operation while the boom is not being operated, the control valve is used to supply hydraulic oil to the boom cylinder.
A shovel according to any one of claims 1 to 3 . supplying hydraulic oil to the boom cylinder using the control valve when the attachment is performing the discharge operation in a state in which there is a relatively high possibility that the dynamic stability of the shovel will decrease;
A shovel according to any one of claims 1 to 4 . The state in which the dynamic stability of the shovel is relatively likely to decrease includes a state in which the bucket is loaded with more than a predetermined amount of material.
The shovel according to claim 5 . The state in which the dynamic stability of the shovel is relatively likely to decrease includes a state in which the speed or acceleration of at least one of the arm and the bucket is relatively large.
The shovel according to claim 5 or 6 . When the attachment performs the discharge operation, the control valve is used to supply hydraulic oil to the boom cylinder at a flow rate corresponding to the acceleration of the boom, the acceleration of the attachment, and a load state of the attachment due to the contents of the bucket.
A shovel according to any one of claims 1 to 7 .

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