control device

Abstract

The characteristic of fully closing the unload valve will be adjusted to an appropriate characteristic depending on the operating conditions of the work machine. [Solution] The controller 70 calculates the actuator target flow rate Qat, which is the target value of the flow rate of oil into the actuator 30, based on the amount of operation used to drive the actuator 30, and controls the opening of the unload valve 43 based on the actuator target flow rate Qat. The controller 70 changes the unload fully closed flow rate Qac according to the conditions related to the usage status of the work machine 10 and the conditions set in the controller 70. The unload fully closed flow rate Qac is the minimum value of the actuator target flow rate Qat when the unload valve 43 is fully closed.

Description

Technical Field

[0001] The present invention relates to a control device for controlling the movement of a working machine.

Background Art

[0002] For example, Patent Document 1 describes a conventional control device. In the invention described in Patent Document 1, the characteristics of the opening area of an unloading valve (a bleed valve in the same document) with respect to the operation amount of an actuator are changed according to the acceleration / deceleration state of the actuator (see the summary of Patent Document 1, FIG. 4, etc.).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the invention described in the same document, when the operation amount of the actuator reaches a certain operation amount, the unloading valve is fully closed. It is desirable to make the characteristic of fully closing the unloading valve an appropriate characteristic according to the usage situation of the working machine.

[0005] Therefore, an object of the present invention is to provide a control device that can make the characteristic of fully closing the unloading valve an appropriate characteristic according to the usage situation of the working machine.

Means for Solving the Problems

[0006] [[ID=)45]] The control device controls the movement of the work machine. The control device comprises a tank, a pump, an actuator, an unload valve, and a controller. The tank stores oil. The pump discharges the oil stored in the tank. The actuator is driven by the oil supplied by the pump. The unload valve adjusts the flow rate of the oil discharged by the pump that flows into the tank without passing through the actuator. The controller calculates an actuator target flow rate, which is a target value for the flow rate of oil into the actuator, based on the amount of operation required to drive the actuator, and controls the opening of the unload valve based on the actuator target flow rate. The controller changes the unload fully closed flow rate, which is the minimum value of the actuator target flow rate when the unload valve is fully closed, according to conditions related to the usage status of the work machine and set in the controller. [Effects of the Invention]

[0007] The control device described above allows the unload valve's characteristic of being fully closed to be adjusted to an appropriate characteristic according to the operating conditions of the work machine. [Brief explanation of the drawing]

[0008] [Figure 1] This is a side view of the control device 1 and its work machine 10. [Figure 2] Figure 1 is a block diagram of the control device 1. [Figure 3] Figure 2 is a graph showing the relationship between the flow rates of the pump 21, actuator 30, and unload valve 43, and the actuator target flow rate Qat. [Figure 4] Figure 2 is a block diagram of the processing of the controller 70. [Figure 5] Figure 2 shows the flowchart (first half) of the processing of the controller 70. [Figure 6] Figure 2 shows the flowchart (second half) of the processing of the controller 70. [Modes for carrying out the invention]

[0009] The control device 1 will be described with reference to Figures 1 to 6.

[0010] The control device 1 is a device that controls the movement of the work machine 10. The control device 1 comprises the work machine 10 shown in Figure 1, the detection unit 50 shown in Figure 2, the input unit 60, the controller 70, and the output unit 80.

[0011] As shown in Figure 1, the work machine 10 is a machine that performs work. The work machine 10 may be a construction machine that performs construction work, or a material handling machine that performs material handling work. The work machine 10 may be, for example, an excavator or a crane. The work machine 10 may be a bulldozer or a wheel loader. The work machine 10 operates in accordance with the operation (manipulation) of a worker (operator). For example, the work machine 10 may be driven (driven by an operator) inside the driver's cab 13c (described later), or it may be remotely driven from outside the work machine 10. The work machine 10 may also be operated by automatic control (described later). Below, we will mainly describe the case where the work machine 10 is an excavator. The work machine 10 comprises a machine body 10a, an attachment 15, and a hydraulic circuit 20 (see Figure 2).

[0012] The machine body 10a is the main body of the work machine 10. The machine body 10a comprises a lower body 11 and an upper rotating body 13.

[0013] The lower body 11 supports the upper rotating body 13 so that it can rotate. The lower body 11 may also be a lower traveling body that can travel on a traveling surface (such as the ground). If the lower body 11 is capable of traveling, it may be equipped with crawlers or wheels.

[0014] The upper slewing body 13 is rotatably mounted on the lower body 11. The upper slewing body 13 is equipped with a control room 13c. The control room 13c is the part from which an operator can operate the work machine 10.

[0015] Attachment 15 is the part where work is performed. Attachment 15 is attached to the machine body 10a. For example, Attachment 15 includes a boom 15a, an arm 15b, and a tip attachment 15c. The boom 15a is rotatably (pivotably) attached to the upper swing body 13. The arm 15b is rotatably attached to the boom 15a.

[0016] The tip attachment 15c is provided at the tip of the attachment 15. The tip attachment 15c is rotatably attached to the arm 15b. The tip attachment 15c may be a bucket capable of performing operations such as scooping up the work object and excavation. The tip attachment 15c may be provided with a device for clamping the work object (such as a grapple, nibbler, rotating fork, etc.), may be provided with a device for crushing the work object (such as a breaker, etc.), or may be provided with a magnet for adsorbing a metallic work object.

[0017] As shown in FIG. 2, the hydraulic circuit 20 is a circuit for moving an actuator 30 (hydraulic actuator) that is driven by hydraulic pressure. The hydraulic circuit 20 controls the actuator 30. The hydraulic circuit 20 includes a tank 20t, a pump 21, a pump capacity control unit 23, an actuator 30, a control valve 41, and an unloading valve 43.

[0018] The tank 20t is a container for storing oil. The oil stored in the tank 20t is oil (hydraulic oil) for moving (operating) the actuator 30 and is oil for moving the working machine 10.

[0019] The pump 21 is a hydraulic pump that discharges the oil stored in the tank 20t. The pump 21 sucks in hydraulic oil from the tank 20t. The pump 21 supplies oil to the actuator 30. The pump 21 is rotated by a drive source. The drive source of the pump 21 may be an engine or an electric motor. Only one pump 21 may be provided, or a plurality of pumps 21 may be provided. The capacity of the pump 21 is variable.

[0020] The pump capacity control unit 23 controls (adjusts) the capacity of the pump 21. The pump capacity control unit 23 controls the capacity of the pump 21 by controlling the tilting angle of the pump 21. Here, the flow rate of the oil discharged by the pump 21 (pump discharge flow rate Qp) is proportional to the rotational speed and capacity of the pump 21. Therefore, as a result of controlling the capacity of the pump 21, the pump capacity control unit 23 controls the pump discharge flow rate Qp. The pump capacity control unit 23 controls the capacity of the pump 21 according to a command input to the pump capacity control unit 23. The command input to the pump capacity control unit 23 may be, for example, a pilot hydraulic pressure or an electric signal (the same applies to the following "command"). Note that the command of the pilot hydraulic pressure is a command in which an electric signal command output by the controller 70 is converted into the pilot hydraulic pressure.

[0021] The actuator 30 is a device that moves the working machine 10. The actuator 30 is a hydraulic actuator that operates by hydraulic pressure. The actuator 30 is connected to the pump 21. "Connected" means that the oil passage is connected. The actuator 30 is driven by the supply of the oil discharged by the pump 21. The actuator 30 may include a motor that rotates or a cylinder that expands and contracts (a telescopic cylinder). As shown in FIG. 1, the actuator 30 includes a travel motor 31, a swing motor 33, a boom cylinder 35a, an arm cylinder 35b, and a tip attachment cylinder 35c.

[0022] The travel motor 31 drives the lower body 11. For example, if the lower body 11 has left and right crawlers, a travel motor 31 is provided to drive the left crawler and another travel motor 31 is provided to drive the right crawler. The travel motor 31 is, for example, a hydraulic motor (the same applies to the slewing motor 33). The slewing motor 33 slewing the upper slewing body 13 relative to the lower body 11. The boom cylinder 35a raises and lowers the boom 15a relative to the upper slewing body 13. The boom cylinder 35a is, for example, a hydraulic cylinder (the same applies to the arm cylinder 35b and the tip attachment cylinder 35c). The arm cylinder 35b rotates the arm 15b relative to the boom 15a. The tip attachment cylinder 35c rotates the tip attachment 15c relative to the arm 15b. If the tip attachment 15c itself is drivable, for example, as a device for gripping objects, an actuator 30 for driving the tip attachment 15c may be provided.

[0023] The control valve 41 (see Figure 2) is a valve that controls the movement of the actuator 30. The control valve 41 shown in Figure 2 is a directional control valve (direction switching valve) that switches the direction of movement of the actuator 30 (for example, rotational direction or extension direction) by switching the direction of oil flow. The control valve 41 changes the drive speed of the actuator 30 by changing the flow rate of oil flowing into (supplied to) the actuator 30. The control valve 41 is installed between the pump 21 and the actuator 30. The "between" refers to the space in the oil passage. The control valve 41 changes the flow rate of oil supplied to the actuator 30 by changing its opening (opening degree) in response to a command (opening command, control valve command) input to the control valve 41. The command input to the control valve 41 may be, for example, pilot hydraulic pressure or an electrical signal. Multiple control valves 41 are provided to control multiple actuators 30. In the example shown in Figure 2, only one control valve 41 controlling one actuator 30 is illustrated.

[0024] The unload valve 43 is a valve (bleed-off valve) that returns the oil discharged by the pump 21 to the tank 20t without passing through the actuator 30. The unload valve 43 is a valve that adjusts the unload flow rate Qu (see Figure 3). The unload flow rate Qu is the flow rate of oil discharged by the pump 21 that the unload valve 43 allows to flow into the tank 20t without passing through the actuator 30. The unload valve 43 is connected to the oil passage between the pump 21 and the control valve 41 and to the tank 20t. The unload valve 43 adjusts the unload flow rate Qu by adjusting its opening in response to commands (opening commands, unload commands) input to the unload valve 43. The unload valve 43 is, for example, an electromagnetic proportional valve, or for example, an electromagnetic proportional pressure reducing valve.

[0025] The detection unit 50 detects various states. Part or all of the detection unit 50 may be mounted on the work machine 10 (see Figure 1) or located outside the work machine 10. The same applies to the input unit 60, controller 70, and output unit 80, which will be described later, in that they may be mounted on the work machine 10 or located outside the work machine 10. The detection unit 50 may detect the state of the work machine 10 or the state of the area outside the work machine 10. The detection unit 50 comprises an actuator speed detection unit 51 and an imaging device 53.

[0026] The actuator speed detection unit 51 detects the speed (drive speed) of the actuator 30. For example, the actuator speed detection unit 51 detects the extension and retraction speed of the hydraulic cylinder. For example, the actuator speed detection unit 51 detects the rotational speed of the hydraulic motor. The actuator speed detection unit 51 may also detect the drive speed of the actuator 30 itself. The actuator speed detection unit 51 may also detect the drive speed of the actuator 30 by detecting the speed of the elements moved by the actuator 30. For example, the actuator speed detection unit 51 may detect the extension and retraction speed of the boom cylinder 35a by detecting the rotational speed of the boom 15a relative to the upper slewing body 13 shown in Figure 1. For example, the actuator speed detection unit 51 outputs a signal (speed signal) indicating the measured speed.

[0027] The imaging device 53 captures an image of the object to be imaged. The imaging device 53 may capture the outside (surroundings) of the work machine 10, capture the work machine 10, or capture the inside of the work machine 10. For example, the imaging device 53 may capture the inside of the driver's cab 13c (it may also be a driver's cab camera). The imaging device 53 may capture the area around the cockpit inside the driver's cab 13c (it may also be a cockpit camera). The imaging device 53 is a camera that detects two-dimensional images. The imaging device 53 may also be capable of detecting three-dimensional images (distance images) that have depth information. The imaging device 53 outputs a signal (image signal) that contains information of the captured image (captured image).

[0028] The input unit 60 (see Figure 2) is a device for inputting information (input device). The input unit 60 is a device for inputting information used for processing by the controller 70. The input unit 60 is operated by an operator and outputs a signal corresponding to the operation. The input unit 60 may be equipped with a touch panel, a mouse, a keyboard, or switches. The input unit 60 may be provided on a tablet, a smartphone, or a personal computer. The input unit 60 may be provided on the work machine 10, for example, in the operator's cab 13c. The input unit 60 may be provided on a device for remotely operating the work machine 10. The input unit 60 may include an operating device 61, include a device provided on the operating device 61, or be provided on the output unit 80. The input unit 60 comprises an operating device 61, a receiver 63, a remote operation response device 65, and an operation mode setting unit 67.

[0029] The operating device 61 is configured to be operated by an operator. The operating device 61 receives input for operations to move the work machine 10 (see Figure 1). The operating device 61 is an actuator operating means that receives input for operations to drive the actuator 30. The operating device 61 may be installed in the operator's cab 13c shown in Figure 1, or it may be installed in a device for remotely operating the work machine 10. The operating device 61 (see Figure 2) may be equipped with a lever or a pedal. The operating device 61 may receive input for operations to move the lower body 11 (travel operations). The operating device 61 may receive input for operations to rotate the upper slewing body 13 relative to the lower body 11 (slewing operations). The operating device 61 may receive input for operations to move the attachment 15 (attachment operations). The operating device 61 may receive input for operations to rotate the boom 15a relative to the upper slewing body 13 (boom operations). The operating device 61 may receive an operation to rotate the arm 15b relative to the boom 15a (arm operation). The operating device 61 may also receive an operation to rotate the tip attachment 15c relative to the arm 15b (tip attachment operation). The operating device 61 outputs a signal (operation signal, command) corresponding to the operation input to the operating device 61. The operating device 61 outputs a command indicating which of the multiple actuators 30 to operate. The operating device 61 outputs a command indicating the speed (operation amount) of the actuator 30. As shown in Figure 2, the operating device 61 comprises an in-cabin operating device 61a and a remote operating device 61b.

[0030] The in-cab operating device 61a is located inside the driver's cab 13c (see Figure 1). The in-cab operating device 61a outputs an operation signal (boarding operation signal) corresponding to the operation input to the in-cab operating device 61a. The operation signal output by the in-cab operating device 61a may be an electrical signal, for example. The in-cab operating device 61a may include, for example, an electric lever or an electric pedal. In this case, the in-cab operating device 61a may be equipped with an angle sensor (for example, a variable resistor) that detects the angle of the lever or pedal. The operation signal output by the in-cab operating device 61a may be pilot hydraulic pressure. In this case, the in-cab operating device 61a may be equipped with a hydraulic remote control valve. In this case, the pilot hydraulic pressure output by the in-cab operating device 61a may be detected by a hydraulic sensor, and the detected value (electrical signal) of the hydraulic sensor may be input to the controller 70.

[0031] The remote control device 61b is located outside the work machine 10 (see Figure 1). The remote control device 61b outputs an operation signal (remote operation signal) corresponding to the operation input to the remote control device 61b. The operation signal output by the remote control device 61b is, for example, an electrical signal.

[0032] The receiver 63 receives various types of information. The receiver 63 is installed in the work machine 10 (see Figure 1) and receives signals arriving from outside the work machine 10.

[0033] The receiver 63 may receive information used for remote operation. The information received by the receiver 63 may include information indicating that remote operation is to be performed, and may also include remote operation signals transmitted by the remote control device 61b. The information received by the receiver 63 is information used for remote operation, and may also include signals output by input units 60 other than the remote control device 61b (e.g., switches).

[0034] The receiver 63 may receive information used for autonomous driving. The receiver 63 may receive information used for autonomous driving from an input unit 60 (e.g., a tablet, personal computer, etc.) located outside the work machine 10 (see Figure 1). The information received by the receiver 63 may include information indicating that autonomous driving is to be performed. The information received by the receiver 63 may include information about the content of autonomous driving, for example, information about the content of the work, or information about the target trajectory of the attachment 15 (see Figure 1). The information received by the receiver 63 may also include operation signals (autonomous driving operation signals) for operating the attachment 15 during autonomous driving.

[0035] The remote operation response device 65 is a device for operating the in-cabin operation device 61a from outside the work machine 10 (see Figure 1). The remote operation response device 65 is a device that is attached to the in-cabin operation device 61a (retrofit device). The remote operation response device 65 performs operations on the in-cabin operation device 61a that are performed on the remote operation device 61b. Specifically, the remote operation device 61b outputs a remote operation signal corresponding to the operation performed on the remote operation device 61b. The receiver 63 receives the remote operation signal. The remote operation response device 65 operates (moves) the in-cabin operation device 61a by moving in response to the remote operation signal received by the receiver 63.

[0036] The operating mode setting unit 67 sets the operating mode according to the operator's operation. The operating mode setting unit 67 is, for example, a switch for switching operating modes. The operating mode is information indicating the method of operation (operation method) of the work machine 10 (see Figure 1), and is information indicating the operation method for driving the actuator 30. There are three operating methods for the work machine 10: onboard operation, remote operation, and operation by automatic control (assisted operation, automatic operation). Onboard operation is an operating method in which the work machine 10 is operated (operated) by an operator inside the operator's cab 13c (see Figure 1). Remote operation is an operating method in which the work machine 10 is operated by an operator from outside the work machine 10 (specifically, from a remote control device 61b, etc.). There are two types of operation by automatic control: assisted operation and automatic operation. Assisted operation is also called machine control system (MC) or semi-automatic operation. Assisted operation is performed as follows. A work plan (work schedule) for the work to be performed by the work machine 10 shown in Figure 1 is set in the controller 70. The operator operates only some elements of the attachment 15 (for example, only the arm 15b). This operation can be performed either while on board or remotely. At this time, the controller 70 automatically controls the elements not operated by the operator (for example, the boom 15a and the tip attachment 15c) so that the work machine 10 moves according to the work plan. As a result, the work machine 10 moves according to the work plan. Automatic operation is a driving method in which the controller 70 controls the movement of the work machine 10 so that the work machine 10 moves automatically according to the work plan. As shown in Figure 2, the operation mode setting unit 67 includes a remote operation mode setting unit 67a, an automatic operation mode setting unit 67b, and an assist operation mode setting unit 67c.

[0037] The remote driving mode setting unit 67a sets the driving mode to remote driving mode. Remote driving mode is a driving mode that indicates that the driving method is remote driving. The automatic driving mode setting unit 67b sets the driving mode to automatic driving mode. Automatic driving mode is a driving mode that indicates that the driving method is automatic driving. The assist driving mode setting unit 67c (for example, assist driving switch, MC switch) sets the driving mode to assist driving mode. Assist driving mode is a driving mode that indicates that the driving method is assist driving. A passenger driving mode setting unit may also be provided to set the driving mode to passenger driving mode. Passenger driving mode is a driving mode that indicates that the driving method is passenger driving.

[0038] The controller 70 is a computer that performs signal input / output, calculations (processing), and information storage. The functions of the controller 70 are realized by the execution of a program stored in the storage unit 70b of the controller 70 by the calculation unit 70a. The controller 70 may be connected to other devices by wireless communication or by wired communication. The components of the controller 70 may be connected to each other by wireless communication or by wired communication. For example, communication is performed by means of communication such as a mobile phone line, optical line, wireless LAN (Local Area Network), or wired LAN. For example, information is input to the controller 70 from the detection unit 50 and the input unit 60. For example, the controller 70 (automatic control unit 73) performs processing to automatically control the work machine 10 (automatic operation, assisted operation). For example, the controller 70 outputs a signal (command) to the hydraulic circuit 20 to operate the work machine 10. For example, the controller 70 outputs information to the output unit 80. The controller 70 may be mounted on the work machine 10 or placed outside the work machine 10. The controller 70 may be distributed across multiple locations (it may constitute a distributed system). The controller 70 comprises a calculation unit 70a and a storage unit 70b. Focusing on the functions of the controller 70, it comprises a hydraulic circuit control unit 71 and an automatic control unit 73.

[0039] The arithmetic unit 70a performs calculations (processing) of information. The storage unit 70b stores the information.

[0040] The hydraulic circuit control unit 71 controls the hydraulic circuit 20. The hydraulic circuit control unit 71 includes an actuator target flow rate setting unit 71a (see Figure 4), a pump control unit 71b, an unload valve control unit 71c, and a control valve control unit 71d.

[0041] The actuator target flow rate setting unit 71a (see Figure 4) sets the actuator target flow rate Qat (see Figure 3, etc.), which is the target value of the flow rate of oil flowing into the actuator 30 (details will be described later). Note that in Figures 4 to 6, "actuator" is sometimes written as "ACT".

[0042] The pump control unit 71b controls the pump 21. Specifically, the pump control unit 71b controls the capacity of the pump 21 by outputting a command to the pump capacity control unit 23 and controlling the pump capacity control unit 23. As a result of controlling the capacity of the pump 21, the pump control unit 71b controls the flow rate of oil discharged by the pump 21 (pump discharge flow rate Qp).

[0043] The unload valve control unit 71c controls the unload valve 43. The unload valve control unit 71c controls the flow rate of oil (unload flow rate Qu (see Figure 3)) that returns from the pump 21 to the tank 20t without going through the actuator 30. Specifically, the unload valve control unit 71c controls the unload flow rate Qu by outputting a command (unload command) to the unload valve 43 and controlling the opening (opening area, opening degree) of the unload valve 43. The unload valve control unit 71c includes, for example, an unload fully closed flow rate setting unit 71c1, an unload state calculation unit 71c2, and an unload command generation unit 71c3, as shown in Figure 4.

[0044] The unload fully closed flow rate setting unit 71c1 sets the unload fully closed flow rate Qac (details will be described later). The unload state calculation unit 71c2 calculates the state of the unload valve 43 (for example, the unload flow rate Qu, or the opening of the unload valve 43) according to the actuator target flow rate Qat (details will be described later). The unload command generation unit 71c3 generates a command (unload command) that the controller 70 outputs to the unload valve 43 (details will be described later).

[0045] As shown in Figure 2, the control valve control unit 71d controls the control valve 41. The control valve control unit 71d controls the movement (driving direction, driving speed) of each actuator 30. Specifically, the control valve control unit 71d outputs commands to the control valve 41 and controls the opening (opening degree) of the control valve 41, thereby controlling the movement of each actuator 30.

[0046] The automatic control unit 73 automatically controls the work machine 10 so that it moves according to the work plan. The work plan is information about the work to be performed by the work machine 10, and is set in the controller 70. The automatic control performed by the automatic control unit 73 may be automatic operation or assisted operation. The automatic control unit 73 outputs commands to the hydraulic circuit 20 so that the work machine 10 moves according to the work plan. The automatic control unit 73 automatically controls the movement of the work machine 10 based on the state of the work machine 10 (position, posture, etc.) detected by the detection unit 50.

[0047] The output unit 80 is an information output device. The output unit 80 outputs information based on a signal output from the controller 70. The output unit 80 may output light (such as a display), sound (such as voice), or vibration. If the output unit 80 outputs light, it may be equipped with a display device (monitor). The output unit 80 may be installed in a tablet, a smartphone, or a personal computer. The output unit 80 may be installed in the driver's cab 13c, for example, in a cluster gauge. The output unit 80 may be installed outside the work machine 10 (it may also be an external output device). The output unit 80 may be installed in a device for remotely controlling the work machine 10.

[0048] (Regarding flow rate) As described above, the flow rate of oil discharged by pump 21 is defined as the pump discharge flow rate Qp. The target value of the pump discharge flow rate Qp is defined as the pump discharge target flow rate Qpt. The measured value of the pump discharge flow rate Qp is defined as the pump discharge actual flow rate Qpr (see Figure 3). When the rotational speed of pump 21 is a predetermined rotational speed, the pump discharge flow rate Qp when the capacity of pump 21 is at its minimum is defined as the pump minimum discharge flow rate Qpmin (see Figure 3), and the pump discharge flow rate Qp when the capacity of pump 21 is at its maximum is defined as the pump maximum discharge flow rate Qpmax (see Figure 3).

[0049] Let the flow rate of oil flowing into actuator 30 be denoted as actuator flow rate Qa. If there are multiple actuators 30 supplied with oil from one pump 21, actuator flow rate Qa is the sum of the flow rates of oil flowing into each actuator 30. If there is only one actuator 30 supplied with oil from one pump 21, let the flow rate of oil flowing into this actuator 30 be denoted as actuator flow rate Qa. Let the target value of actuator flow rate Qa be actuator target flow rate Qat (see Figure 3). Let the measured value of actuator flow rate Qa be actuator actual flow rate Qar (see Figure 3). The above "flow rate of oil flowing into each actuator 30" is also called "flow rate of each actuator 30". The target value of the flow rate of each actuator 30 is also called "target flow rate of each actuator 30". The measured value of the flow rate of each actuator 30 is also called "actual flow rate of each actuator 30".

[0050] Let Qu be the flow rate of oil flowing from the unload valve 43 into the tank 20t. The sum of the unload flow rate Qu and the actuator flow rate Qa is the pump discharge flow rate Qp.

[0051] (Operation) The control device 1 (mainly the controller 70) shown in Figure 2 operates as follows.

[0052] The controller 70 (more specifically, the hydraulic circuit control unit 71) controls the hydraulic circuit 20 as follows: The controller 70 acquires the actuator operation amount. The actuator operation amount is the operation amount for driving the actuator 30. Specifically, when the operating method of the work machine 10 (see Figure 1 (the same applies to the work machine 10 below)) is onboard operation, the actuator operation amount is the operation amount of the in-cabin operating device 61a (e.g., lever angle, pedal angle, etc.). When the operating method of the work machine 10 is remote operation, the actuator operation amount is the operation amount of the remote operating device 61b. When the operating method of the work machine 10 is automatic operation, the actuator operation amount is the operation amount of the actuator 30 calculated (generated) by the controller 70. When the operating method of the work machine 10 is assisted operation, the actuator operation amount is the operation amount of the operating device 61 operated by the operator and the operation amount calculated by the controller 70.

[0053] The controller 70 controls the pump discharge flow rate Qp, the flow rate of each actuator 30, and the unload flow rate Qu based on the actuator operation amount. More specifically, the controller 70 calculates the actuator target flow rate Qat based on the actuator operation amount (step S23 in Figure 5). More specifically, the controller 70 calculates the target flow rate for each actuator based on the operation amount of each actuator 30 (step S22). The controller 70 calculates the actuator target flow rate Qat from the sum of the target flow rates of each actuator (step S23). Then, the controller 70 controls the pump 21, the unload valve 43, and the control valve 41 so that oil at the actuator target flow rate Qat flows into the actuator 30 (for further details, see the explanation of steps S51 to S74 shown in Figure 6 (described later)).

[0054] (Change in unloading fully closed flow rate Qac) As shown in Figure 4, the controller 70 (specifically, the unload valve control unit 71c) calculates the state of the unload valve 43 (for example, the unload flow rate Qu) based on the actuator target flow rate Qat. At this time, the controller 70 (specifically, the unload fully closed flow rate setting unit 71c1) changes the characteristic (timing) of fully closing the unload valve 43 according to the unload fully closed flow rate change conditions described later. Specifically, the controller 70 changes the unload fully closed flow rate Qac according to the unload fully closed flow rate change conditions. As shown in Figure 3, the unload fully closed flow rate Qac is the minimum value of the actuator target flow rate Qat when the unload valve 43 is fully closed. That is, the controller 70 fully closes the unload valve 43 if the actuator target flow rate Qat is equal to or greater than the unload fully closed flow rate Qac.

[0055] As the unload closing flow rate Qac decreases (for example, from flow rate Qat-1 to flow rate Qat-2), the minimum value of the actuator target flow rate Qat at which the unload valve 43 is fully closed decreases. For example, suppose the actuator operation amount gradually increases, and the actuator target flow rate Qat gradually increases. In this case, the smaller the unload closing flow rate Qac, the earlier the unload valve 43 will be fully closed (at a smaller actuator target flow rate Qat). When the unload valve 43 shown in Figure 2 is fully closed, all the oil discharged by the pump 21 (excluding slight leaks) is supplied to the actuator 30. Therefore, as the unload closing flow rate Qac shown in Figure 3 decreases, the loss of hydraulic energy of the oil discharged by the pump 21 (see Figure 2) is suppressed, and the fuel efficiency of the work machine 10 is improved.

[0056] As the unload closing flow rate Qac increases (for example, from flow rate Qat-1 to flow rate Qat-3), the minimum value of the actuator target flow rate Qat at which the unload valve 43 is fully closed increases (see flow rate Qat-3 for flow rate Qat-1). For example, suppose the actuator operation amount gradually increases, and the actuator target flow rate Qat gradually increases. In this case, the larger the unload closing flow rate Qac, the later the unload valve 43 will close (at a larger actuator target flow rate Qat). Therefore, even if the actuator operation amount is changed significantly, the speed of the actuator 30 (see Figure 2) will not change as easily. Thus, the fine control performance of the actuator 30 is improved. For example, when an operator operates the work machine 10 (onboard operation, remote operation), the feel of operation of the control device 61 (see Figure 2) is improved. In addition, regardless of the operating method, the accuracy of operation of the actuator 30 (see Figure 2) is improved. Therefore, for example, the positioning accuracy of the attachment 15 shown in Figure 1 is improved (becomes advantageous), and the accuracy of work performed by the attachment 15 (e.g., construction) is improved.

[0057] The unload total closed flow rate Qac shown in Figure 3 may be continuously changeable or stepwise changeable. When the unload total closed flow rate Qac is changed stepwise, the steps are also called the unload operation mode. The number of these steps may be two or three or more. For example, the unload operation mode may include an operability priority mode and an energy saving priority mode. The unload total closed flow rate Qac in the energy saving priority mode is smaller than the unload total closed flow rate Qac in the operability priority mode. In addition, unload operation modes other than the operability priority mode and energy saving priority mode may be set. For example, an unload operation mode for the unload total closed flow rate Qac between the energy saving priority mode and the operability priority mode (e.g., standard mode, intermediate mode, etc.) may be set.

[0058] (Explanation of the specific example in Figure 3) Let's further explain the specific example shown in Figure 3. The horizontal axis of the graph in Figure 3 represents the actuator target flow rate Qat. This horizontal axis may also represent the actuator operation amount. The vertical axis of this graph represents the opening of the unload valve 43 (see Figure 2) (unload opening) (dotted line), the actual actuator flow rate Qar (dashed line), and the actual pump discharge flow rate Qpr (solid line). The unload flow rate Qu is obtained by subtracting the actual actuator flow rate Qar from the actual pump discharge flow rate Qpr.

[0059] In the graph shown in Figure 3, when the actuator target flow rate Qat is 0, the controller 70 (see Figure 2 (the same applies to the controller 70 below)) sets the actual pump discharge flow rate Qpr to the minimum pump discharge flow rate Qpmin. At this time, the controller 70 sets the capacity of the pump 21 (see Figure 2) to its minimum (the smallest capacity among the variable capacity of the pump 21). When the actuator target flow rate Qat is 0, the controller 70 fully opens the unload valve 43 (see Figure 2).

[0060] Furthermore, when the operating device 61 (see Figure 2) is not being operated (for example, the lever is in the neutral position and the pedal is not pressed), the actuator operating amount is 0 and the operation signal is off (NO in step S21 of Figure 5) until the operating amount reaches a predetermined operating amount. At this time, the actuator target flow rate Qat is 0, and the controller 70 does not drive the actuator 30 (see Figure 2). Also, when the operating amount of the operating device 61 exceeds the above-mentioned "predetermined operating amount", the actuator operating amount becomes greater than 0, and the operation signal becomes on (YES in step S21 of Figure 5). At this time, the actuator target flow rate Qat becomes greater than 0, and the controller 70 drives the actuator 30 in response to the operation of the operating device 61.

[0061] When the actuator target flow rate Qat is between 0 and a certain flow rate Qat-1 (unloaded fully closed flow rate Qac), the controller 70 increases the actual pump discharge flow rate Qpr as the actuator target flow rate Qat increases. At this time, the controller 70 decreases the opening of the unload valve 43 as the actuator target flow rate Qat increases. The opening area of ​​the unload valve 43 decreases, for example, to about 80 mm² as the actuator target flow rate Qat increases. 2 It is then gradually reduced in size.

[0062] When the actuator target flow rate Qat is Qat-1 (unload fully closed flow rate Qac), the controller 70 fully closes the unload valve 43. In this case, as shown in the example in Figure 3, the controller 70 sets the actual pump discharge flow rate Qpr to half of the maximum pump discharge flow rate Qpmax.

[0063] When the actuator target flow rate Qat is greater than the flow rate Qat-1, the controller 70 closes the unload valve 43 completely. When the actuator target flow rate Qat is greater than the flow rate Qat-1, the controller 70 increases the actual pump discharge flow rate Qpr as the actuator target flow rate Qat increases.

[0064] When the actuator target flow rate Qat is at its maximum (when the actuator operation amount is at its maximum), the controller 70 sets the actual pump discharge flow rate Qpr to the maximum pump discharge flow rate Qpmax. At this time, the controller 70 sets the capacity of the pump 21 to its maximum (the largest capacity among the variable capacity of the pump 21).

[0065] Let's explain the case where the unload closing flow rate Qac is reduced, using an example shown in Figure 3. For example, suppose the unload closing flow rate Qac is changed to a flow rate Qat-2 which is less than Qat-1 but greater than 0. In this case, the actuator target flow rate Qat is gradually increased from 0, and when it reaches Qat-2 (earlier than when it reaches Qat-1), the controller 70 completely closes the unload valve 43. In the example shown in Figure 3, the controller 70 completely closes the unload valve 43 before the actual pump discharge flow rate Qpr becomes half of the maximum pump discharge flow rate Qpmax (earlier). As shown in Figure 3, when the unload closing flow rate Qac is reduced, the ratio of the change in the actual actuator flow rate Qar to the change in the actuator target flow rate Qat (the slope of the graph of the actual actuator flow rate Qar) becomes larger.

[0066] Let's explain the case where the unload valve closing flow rate Qac is increased, using an example shown in Figure 3. For example, suppose the unload valve closing flow rate Qac is changed to a flow rate Qat-3, which is greater than the flow rate Qat-1. Here, the flow rate Qat-3 is less than or equal to the maximum value of the actuator target flow rate Qat (the maximum pump discharge flow rate Qpmax). In this case, when the actuator target flow rate Qat is gradually increased from 0 and reaches the flow rate Qat-3 (later than when it reaches the flow rate Qat-1), the controller 70 completely closes the unload valve 43. The unload valve 43 gradually closes as the actuator operation amount is gradually increased from 0. In the example shown in Figure 3, the controller 70 completely closes the unload valve 43 after the actual pump discharge flow rate Qpr has become half of the maximum pump discharge flow rate Qpmax (later). As shown in Figure 3, when the unload valve closing flow rate Qac is increased, the ratio of the change in the actual actuator flow rate Qar to the change in the actuator target flow rate Qat (the slope of the graph of the actual actuator flow rate Qar) becomes smaller (gentler). Therefore, the change in the speed of the actuator 30 becomes smaller in response to changes in the actuator's operating amount (improving fine controllability).

[0067] (Unloading fully closed flow rate change conditions) The controller 70 changes the unload total closed flow rate Qac according to the conditions set in the controller 70 (unload total closed flow rate change conditions). The unload total closed flow rate change conditions are conditions related to the usage status of the work machine 10. The unload total closed flow rate change conditions can be set in various ways. Specifically, the unload total closed flow rate change conditions may include conditions for the operating mode, conditions for the work content, other conditions, or a combination of multiple conditions.

[0068] The unload total closed flow rate change conditions may include conditions indicating that the usage situation prioritizes operability. The controller 70 may increase the unload total closed flow rate Qac when the conditions indicating that the usage situation prioritizes operability are met (for example, it may be set to operability priority mode). The controller 70 may decrease the unload total closed flow rate Qac when the conditions indicating that the usage situation prioritizes operability are not met (for example, it may be set to energy saving priority mode). In addition, the unload total closed flow rate change conditions may include conditions indicating that the usage situation prioritizes the reduction of hydraulic energy (energy saving). The controller 70 may decrease the unload total closed flow rate Qac when the conditions indicating that the usage situation prioritizes energy saving are met (for example, it may be set to energy saving priority mode). The controller 70 may increase the unload total closed flow rate Qac when the conditions indicating that the usage situation prioritizes energy saving are not met (for example, it may be set to operability priority mode).

[0069] (Operating mode conditions) The unload total closed flow rate change conditions may include conditions for the operating mode. The controller 70 may change the unload total closed flow rate Qac according to the operating mode. For example, the controller 70 may change the unload total closed flow rate Qac depending on which of the following operating modes is in operation: onboard operation mode, remote operation mode, assisted operation mode, and automatic operation mode (see steps S12 to S14n in Figure 5, etc.).

[0070] Specific examples of the relationship (assignment) between the operating mode and the unload total closed flow rate Qac are as follows: In operating modes where the operator manually operates the work machine 10 (specifically, the onboard operation mode and the remote operation mode), there is a greater need to prioritize the operability of the control device 61 compared to when the work machine 10 is automatically controlled. Therefore, the controller 70 may set the unload total closed flow rate Qac to be larger in operating modes where the operator manually operates the work machine 10 compared to other operating modes (for example, it may be set to an operability priority mode). Also, in operating modes where the controller 70 automatically controls the work machine 10 (specifically, the assist operation mode and the automatic operation mode), there is a smaller need to prioritize the operability of the control device 61 (smaller than in onboard operation and remote operation). Therefore, the controller 70 may set the unload total closed flow rate Qac to be smaller in operating modes where the controller 70 automatically controls the work machine 10 compared to other operating modes (for example, it may be set to an energy saving priority mode). However, even in assisted and automated operation, depending on the work performed by the work machine 10, it may be preferable to increase the unload fully closed flow rate Qac (see below). Also, in onboard and remote operation, depending on the work performed by the work machine 10, the unload fully closed flow rate Qac may be reduced.

[0071] (Setting and determining the driving mode) The operating mode may be manually set by the operator, or it may be set by the operating mode setting unit 67 shown in Figure 2, for example. The operating mode may also be automatically determined by the controller 70 (operating mode determination process). In determining the operating mode, the controller 70 may perform automatic determination using operation signals, automatic determination using the imaging device 53, or automatic determination combining these methods.

[0072] (Manual operation to set the operating mode) The controller 70 may set the operating mode according to a manual setting made by the operating mode setting unit 67 (for example, a switch). For example, the operating mode setting unit 67 outputs a signal (operating mode signal) to the controller 70 indicating which operating mode is in response to an operation performed by the operator. The controller 70 determines (sets) the operating mode according to the operating mode signal. Then, the controller 70 sets the unload fully closed flow rate Qac (see Figure 3) according to the operating mode.

[0073] (Automatic detection of driving mode) The controller 70 may determine the operating mode from the signals (operation signals) that operate the actuator 30. For example, if the controller 70 receives an operation signal (onboard operation operation signal) from the driver's cab operation device 61a, it determines that the operating mode is onboard operation mode. If the controller 70 receives an operation signal (remote operation operation signal) from the remote operation device 61b via the receiver 63, it determines that the operating mode is remote operation mode. If the controller 70 (specifically the automatic control unit 73) generates an operation signal for assisted operation (assisted operation operation signal), the controller 70 determines that the operating mode is assisted operation mode. If the controller 70 (specifically the automatic control unit 73) generates an operation signal for automatic operation (automatic operation operation signal), the controller 70 determines that the operating mode is automatic operation mode.

[0074] The controller 70 may determine the operating mode based on the image of the interior of the driver's cab 13c captured by the imaging device 53 shown in Figure 1. In this case, the controller 70 determines the operating mode by performing image recognition (image detection) on the captured image.

[0075] For example, the controller 70 may determine whether the operating mode is remote operation mode based on whether the remote operation response device 65 is visible in the captured image. The controller 70 may determine that the operating mode is remote operation mode if the remote operation response device 65 is visible in the captured image. Alternatively, the controller 70 may determine whether the operating mode is remote operation mode based on whether the remote operation response device 65 is moving (operating) the in-cabin operating device 61a. The controller 70 may determine that the operating mode is remote operation mode if the remote operation response device 65 is moving the in-cabin operating device 61a.

[0076] The controller 70 may determine whether the operating mode is "onboard driving mode or assisted driving mode" based on whether or not an operator is visible in the captured image. The controller 70 may determine that the operating mode is "onboard driving mode or assisted driving mode" if an operator is visible in the captured image. The controller 70 may also determine whether the operating mode is "onboard driving mode or assisted driving mode" based on whether or not an operator is operating the in-cabin operating device 61a. The controller 70 may determine that the operating mode is "onboard driving mode or assisted driving mode" if an operator is operating the in-cabin operating device 61a.

[0077] The controller 70 may determine the operating mode by combining multiple types of information. For example, the controller 70 may set (determine) the operating mode based on two or more types of information from among manual operation information, operation signal information, and captured image information (see steps S12 to S14n in Figure 5).

[0078] (Conditions for the work content) The unload full-close flow rate change conditions may include conditions related to the content of the work performed by the work machine 10 (referred to as the work content). The controller 70 may change the unload full-close flow rate Qac according to the work content. For example, the work content may be set in the controller 70 when the operating mode is automatic operation mode or assist operation mode. Also, the work content may be set in the controller 70 when the operating mode is onboard operation mode or remote operation mode. The controller 70 may then change the unload full-close flow rate Qac according to the set work content.

[0079] Specific examples of the relationship (allocation) between the work content and the unload total closed flow rate Qac are as follows: In work where the accuracy of the position of the attachment 15 shown in Figure 1 is important, it is necessary to prioritize the operability of the actuator 30. Examples of work where the accuracy of the position of the attachment 15 is important include work that shapes terrain (such as embankments) (shaping work, finishing work), or work that requires the precise movement of the work object. In such work where it is necessary to prioritize the operability of the actuator 30, the controller 70 increases the unload total closed flow rate Qac (see Figure 3) compared to work where it is not necessary to prioritize the operability of the actuator 30. For example, the controller 70 sets the unload operation mode to operability priority mode. In work where it is not necessary to prioritize the operability of the actuator 30, the controller 70 decreases the unload total closed flow rate Qac compared to work where it is necessary to prioritize the operability of the actuator 30. For example, the controller 70 sets the unload operation mode to energy saving priority mode.

[0080] The nature of the work (for example, whether or not it is a task where ease of operation is a major priority) may be manually set by the input unit 60, or the controller 70 may automatically determine it from information such as the work plan.

[0081] (Conditions for operating mode and work content, etc.) The unload total closed flow rate change conditions may include conditions for the operating mode and work content. The controller 70 may change the unload total closed flow rate Qac (see Figure 3) according to the conditions for the operating mode and work content. Note that the unload total closed flow rate change conditions may also include conditions other than the operating mode and work content. The controller 70 may change the unload total closed flow rate Qac according to conditions other than the operating mode and work content. For example, the controller 70 may change the unload total closed flow rate Qac according to the operation of a switch different from the operating mode setting unit 67.

[0082] (allocation) The relationship (assignment) between the unload full-close flow rate change conditions and the unload full-close flow rate Qac (see Figure 3) can be set in various ways. This assignment may be set arbitrarily by the operator via the input unit 60 (see Figure 2) (manual setting), may be set in advance by the controller 70, or the controller 70 may automatically set and change it according to the conditions.

[0083] For example, the controller 70 may set the initial mode (default) of the unload operation mode to the operability priority mode. Furthermore, the conditions (situations) for setting the unload operation mode to the energy saving priority mode may be set according to the operator's operation of the input unit 60.

[0084] Furthermore, for example, if the operating mode is onboard operation or remote operation, the controller 70 may set the unload operation mode to an operability-priority mode. If the operating mode is assisted operation or automatic operation and the work requires a high degree of operability priority, the controller 70 may set the unload valve operation mode to an operability-priority mode. If the operating mode is assisted operation or automatic operation and the work requires little priority on operability, the controller 70 may set the unload valve operation mode to an energy-saving priority mode.

[0085] (Specific examples of how to change the unloaded, fully closed flow rate Qac) The process of changing the unloading fully closed flow rate Qac, as shown in Figure 4, and the process of determining the opening of the unloading valve 43 (unloading opening) based on the changed unloading fully closed flow rate Qac, may be carried out in various ways. An example of these processes will be described below.

[0086] (Setting of unload fully closed flow rate Qac) As described above, the controller 70 (specifically, the unload total closed flow rate setting unit 71c1) changes the unload total closed flow rate Qac according to the unload total closed flow rate change conditions. Specifically, the relationship (assignment) between the unload total closed flow rate change conditions and the unload total closed flow rate Qac is set in the controller 70. The controller 70 acquires information to determine the unload total closed flow rate change conditions (for example, operating mode, work content, etc.). Then, based on the acquired information and the assignment information described above, the controller 70 determines the unload total closed flow rate Qac (in this example, 50 L / min).

[0087] (Settings for Unload Status Map M) The controller 70 (specifically, the unload state calculation unit 71c2) performs the following processing: The controller 70 sets the unload state map M based on the unload fully closed flow rate Qac (for example, 50 L / min) set in the unload fully closed flow rate setting unit 71c1. The unload state map M is information (map) that shows the relationship between the actuator flow rate Qa and the state of the unload valve 43. For example, the unload state map M may also be information (unload flow rate map Ma) that shows the relationship between the actuator target flow rate Qat and the unload flow rate Qu. The unload state map M may also be information (unload opening map Mb) (see Figure 3) that shows the relationship between the actuator target flow rate Qat and the opening of the unload valve 43 (unload opening).

[0088] A specific example of the unload state map M is as follows: In the unload flow rate map Ma, when the actuator target flow rate Qat is less than the unload total closing flow rate Qac, the unload flow rate Qu decreases from its maximum value as the actuator target flow rate Qat increases from 0. Also, when the actuator target flow rate Qat is greater than or equal to the unload total closing flow rate Qac, the unload flow rate Qu becomes 0. In the unload opening map Mb shown in Figure 3, when the actuator target flow rate Qat is less than the unload total closing flow rate Qac, the unload opening decreases from a predetermined opening (e.g., 80 mm) as the actuator target flow rate Qat increases from 0. 2 ) becomes smaller. In the unload opening map Mb, the unload opening becomes fully closed when the actuator target flow rate Qat is greater than or equal to the unload fully closed flow rate Qac. Below, as an example of the unload state map M, we will mainly describe the unload flow rate map Ma shown in Figure 4. If the unload state map M is the unload opening map Mb (see Figure 3), then in the following explanation, replace the unload flow rate Qu with the unload opening.

[0089] For example, the controller 70 may read an unload state map M corresponding to an unload fully closed flow rate Qac (e.g., 50 L / min) set in the unload fully closed flow rate setting unit 71c1. In this case, the controller 70 may store unload state maps M corresponding to various unload fully closed flow rates Qac in advance (before calculating the state of the unload valve 43).

[0090] Furthermore, for example, the controller 70 may modify (correct) the pre-stored unload state map M according to the unload total closing flow rate Qac. Specifically, the controller 70 pre-stores information about the shape (e.g., the shape of the graph) of the unload state map M. The controller 70 may then change the scale of the actuator target flow rate Qat in the unload state map M according to the unload total closing flow rate Qac. Specifically, the controller 70 changes the scale such that the unload flow rate Qu is greater than 0 when the actuator target flow rate Qat is less than the unload total closing flow rate Qac, and becomes 0 when the unload flow rate Qu is equal to or greater than the unload total closing flow rate Qac.

[0091] A further specific example of changing the scale of the actuator target flow rate Qat is as follows: The controller 70 divides the unload fully closed flow rate Qac (e.g., 50 L / min) by the number of map divisions. This "number of map divisions" represents the resolution (level of detail, coarseness or fineness of scale) of the unload flow rate map Ma. The value obtained by dividing the unload fully closed flow rate Qac by the number of map divisions is taken as the "unit flow rate" (one division, one step on the map) of the actuator target flow rate Qat in the unload state map M. For example, if the unload fully closed flow rate Qac is 50 L / min and the number of map divisions is 5, then the unit flow rate of the actuator target flow rate Qat in the unload flow rate map Ma is 10 L / min. The unload flow rate map Ma is a map in which the unload flow rate Qu is set (plotted) for each unit flow rate (e.g., 10 L / min). Furthermore, if the actuator target flow rate Qat is not an integer multiple of the unit flow rate, the unload flow rate Qu is interpolated (e.g., linear interpolation) based on the set unload flow rate Qu value.

[0092] The controller 70 multiplies the unit flow rate (e.g., 10 L / min) by an array of positive integers (0, 1, 2, ... n-1, n). n is the maximum value (last element) of the array and is greater than the number of map divisions (e.g., 5), which is 7 in the example shown in Figure 4. The maximum value (n) of the array may be variable. The controller 70 uses the value obtained by multiplying the unit flow rate (e.g., 10 L / min) by the array of positive integers (0, 10, 20, ... 10(n-1), 10n) as the scale for the actuator target flow rate Qat in the unload flow rate map Ma. As a result, the unload flow rate map Ma becomes a map where the unload flow rate Qu is greater than 0 when the actuator target flow rate Qat is less than the unload fully closed flow rate Qac, and 0 when the unload fully closed flow rate Qat is greater than or equal to the unload fully closed flow rate Qac.

[0093] (Determination of the target state of the unload valve 43 according to the actuator target flow rate Qat) As described above, the controller 70 (specifically, the actuator target flow rate setting unit 71a) calculates the actuator target flow rate Qat based on the actuator operation amount (see also step S23 in Figure 5). Then, the controller 70 (specifically, the unload state calculation unit 71c2) determines the target state of the unload valve 43 corresponding to the calculated actuator target flow rate Qat based on the set unload state map M. For example, the controller 70 determines the target value of the unload flow rate Qu corresponding to the actuator target flow rate Qat based on the unload flow rate map Ma. For example, the controller 70 may determine the target value of the unload opening corresponding to the actuator target flow rate Qat based on the unload opening map Mb (see Figure 3).

[0094] (Generate unload command) The controller 70 (specifically, the unload command generation unit 71c3) generates (calculates) a command (unload command) to output to the unload valve 43 according to the target value of the state of the unload valve 43 determined by the unload state calculation unit 71c2. The unload command is, for example, a current value. Specifically, the controller 70 stores information (unload command map) in advance (before determining the unload command) about the relationship between the state of the unload valve 43 (unload flow rate Qu or unload opening) and the unload command. Based on the unload command map, the controller 70 generates an unload command corresponding to the target value of the state of the unload valve 43 determined by the unload state calculation unit 71c2. Then, the controller 70 outputs the generated unload command to the unload valve 43.

[0095] (Information output) The controller 70 outputs information indicating the state (status, current status) of the unload fully closed flow rate Qac to the output unit 80 (see Figure 2). The controller 70 may output a display, an audio output, or both a display and an audio output to the output unit 80. The "information indicating the state of the unload fully closed flow rate Qac" that the controller 70 outputs to the output unit 80 may be the value of the unload fully closed flow rate Qac (e.g., 50 L / min). The information indicating the state of the unload fully closed flow rate Qac may also be information indicating which unload operation mode (e.g., energy saving priority mode, operability priority mode, etc.) is set. By having the controller 70 output information indicating the state of the unload fully closed flow rate Qac to the output unit 80, the status of the unload fully closed flow rate Qac can be made known to the operator. For example, the operator can be made aware of whether an appropriate unload fully closed flow rate Qac is set according to the operating mode, work content, etc.

[0096] (Flowchart of the processing of controller 70) A specific example of the processing of the controller 70 will be explained with reference to the flowcharts shown in Figures 5 and 6. Unless otherwise specified, the explanation will follow the order of processing. Note that the order of processing can be changed in various ways. Steps S11 to S35 shown in Figure 5 will be explained with reference to Figure 5.

[0097] In the state prior to step S11 (start), the work machine 10 is in an idling state, and the actuator 30 shown in Figure 1 is not moving.

[0098] In step S11, the controller 70 sets the assignment of the unload operation mode. Specifically, the controller 70 sets the relationship (assignment) between the unload total closing flow rate change conditions (e.g., operating mode, work content, etc.) and the unload operation mode (e.g., energy saving priority mode, operability priority mode, etc.). As described above, this assignment may be set by the operator through manual operation of the input unit 60 shown in Figure 2, may be pre-set in the controller 70, or may be set automatically by the controller 70.

[0099] In steps S12 to S14n, the controller 70 determines the unload fully closed flow rate change condition. The example shown in Figure 5 is an example in which the controller 70 determines the operating mode based on the operation signal and the setting in the operating mode setting unit 67. Specifically, the controller 70 determines that the operating mode is remote operation mode (step S12y) when a remote operation operation signal is input from the remote control device 61b shown in Figure 2 (if it is ON) (if it is YES in step S12). The controller 70 determines that the operating mode is automatic operation mode (step S13y) when the automatic control unit 73 is generating an automatic operation operation signal (if it is ON) (if it is YES in step S13). The controller 70 determines that the operating mode is assist operation mode (step S14y) when assist operation is selected in the assist operation mode setting unit 67c (MC switch in Figure 5) (if it is ON) (if it is YES in step S14). If the answer in step S14 is NO, the controller 70 determines that the operating mode is the passenger operation mode (step S14n). After determining the unload fully closed flow rate change condition, the controller 70 performs the process in step S21.

[0100] In step S21, the controller 70 determines whether the actuator operation amount is an operation amount that drives the actuator 30 (determines whether the operation signal is ON or OFF). If the actuator operation amount is an operation amount that drives the actuator 30 (if YES in step S21), the controller 70 performs the process in step S22. If the actuator operation amount is not an operation amount that drives the actuator 30, the controller 70 waits until it becomes an operation amount that drives the actuator 30 (until it turns ON). Note that it may be possible to supply oil to multiple actuators 30 from one pump 21. In this case, the controller 70 determines that the actuator operation amount is an operation amount that drives the actuator 30 if an operation to drive at least one of these multiple actuators 30 is performed.

[0101] In step S22, the controller 70 calculates the target flow rate for each actuator 30 (the target value of the flow rate of oil flowing into each actuator 30) from the actuator operating amount (e.g., lever angle) for each actuator 30. The controller 70 may also calculate the target speed for each actuator 30. The speed of the actuator 30 and the flow rate of oil supplied to the actuator 30 are mutually interchangeable. Note that in Figure 5, "actuator" is written as "ACT" (the same applies to Figures 4 and 6).

[0102] In step S23, the controller 70 calculates the actuator target flow rate Qat, which is the sum of the target flow rates of each actuator 30.

[0103] In steps S31 to S33, the controller 70 sets the unload total closed flow rate Qac based on the unload total closed flow rate change conditions. In the example shown in Figure 5, there are two unload operation modes: an energy-saving priority mode and an operability priority mode. In step S31, the controller 70 determines whether or not to set the unload operation mode to the energy-saving priority mode. Specifically, the controller 70 determines whether or not the conditions for setting the unload operation mode to the energy-saving priority mode (unload total closed flow rate change conditions) are met. If the controller 70 determines that the unload operation mode should be set to the energy-saving priority mode (YES in step S31), it sets the unload operation mode to the energy-saving priority mode. In this case, the controller 70 makes the unload total closed flow rate Qac smaller than the unload total closed flow rate Qac in the operability priority mode (step S32). If the controller 70 determines that the unload operation mode should not be set to the energy-saving priority mode (NO in step S31), it sets the unload operation mode to the operability priority mode. In this case, the controller 70 makes the unload fully closed flow rate Qac greater than the unload fully closed flow rate Qac in the energy saving priority mode (step S33).

[0104] In step S34, as shown in Figure 4, the controller 70 (specifically, the unload state calculation unit 71c2) sets the unload state map M according to the unload total closing flow rate change conditions. Specifically, the controller 70 sets (for example, modifies) the unload flow rate map Ma depending on whether the unload operation mode is the energy saving priority mode or not (details are as described above).

[0105] In step S35, the controller 70 (specifically, the unload state calculation unit 71c2) calculates a target value for the state of the unload valve 43 according to the actuator target flow rate Qat based on the unload state map M (details are as described above). For example, the controller 70 calculates a target value for the unload flow rate Qu according to the actuator target flow rate Qat based on the unload flow rate map Ma. Steps S41 to S74 shown in Figure 6 will be explained below with reference to Figure 6.

[0106] In step S41, the controller 70 acquires the actual flow rate of each actuator 30 shown in Figure 1. Specifically, the controller 70 acquires the drive speed of each actuator 30 detected by the actuator speed detection unit 51 shown in Figure 2. The controller 70 converts the drive speed of each actuator 30 into the flow rate (actual flow rate) of oil flowing into each actuator 30. Alternatively, the actual flow rate of each actuator 30 may be detected by a flow sensor. The controller 70 may acquire the actual flow rate of each actuator 30 detected by the flow sensor.

[0107] In steps S51 to S74 (control processing), the controller 70 controls the pump 21, control valve 41, and unload valve 43 so that oil at a flow rate of actuator target flow rate Qat (see Figure 3) flows into the actuator 30.

[0108] (Pump control processing) In steps S51 to S54, the controller 70 (specifically the pump control unit 71b) controls the pump discharge flow rate Qp based on the actuator target flow rate Qat (see steps S23 in Figure 5 and Figure 3).

[0109] In step S51, the controller 70 calculates the actual flow rate of oil discharged by the pump 21 (actual pump discharge flow rate Qpr (see Figure 3)). The actual pump discharge flow rate Qpr is the sum of the actual flow rates of each actuator 30 (see step S41) (actuator actual flow rate Qar) and the unload flow rate Qu (see step S35 in Figure 5). The actual pump discharge flow rate Qpr (see Figure 3) may also be detected by a flow sensor. The controller 70 may acquire the actual pump discharge flow rate Qpr detected by the flow sensor.

[0110] In step S52, the controller 70 performs feedback control of the pump discharge flow rate Qp. Specifically, the controller 70 calculates a target value for the flow rate of oil discharged by the pump 21 (target pump discharge flow rate Qpt). The target pump discharge flow rate Qpt is the sum of the actuator target flow rate Qat (see step S23 in Figure 5 and Figure 3) and the unload flow rate Qu (see step S35 in Figure 5). The controller 70 then controls the pump discharge flow rate Qp so that the deviation of the actual pump discharge flow rate Qpr from the target pump discharge flow rate Qpt is small (compensates for the target pump discharge flow rate Qpt). Specifically, the controller 70 controls the pump discharge flow rate Qp by controlling the capacity of the pump 21.

[0111] For example, during acceleration of the actuator 30 shown in Figure 2, it is conceivable that the actual actuator flow rate Qar (see Figure 3) does not reach the actuator target flow rate Qat (see Figure 3) (i.e., the speed of the actuator 30 does not reach the target). In this case, the actual pump discharge flow rate Qpr (see step S51 in Figure 6) is smaller than the target pump discharge flow rate Qpt. Therefore, the controller 70 controls the system to increase the target pump discharge flow rate Qpt and the pump discharge flow rate Qp in accordance with the deviation of the actual pump discharge flow rate Qpr from the target pump discharge flow rate Qpt. Also, for example, during deceleration of the actuator 30, it is conceivable that the actual actuator flow rate Qar exceeds the actuator target flow rate Qat (i.e., the speed of the actuator 30 exceeds the target). In this case, the actual pump discharge flow rate Qpr is larger than the target pump discharge flow rate Qpt. Therefore, the controller 70 controls the system to decrease the target pump discharge flow rate Qpt and the pump discharge flow rate Qp in accordance with the deviation of the actual pump discharge flow rate Qpr from the target pump discharge flow rate Qpt. Furthermore, for example, due to variations in the equipment characteristics of the pump 21, it is conceivable that the actual pump discharge flow rate Qpr may deviate from the target pump discharge flow rate Qpt (an error may occur). In this case, the controller 70 modifies the target pump discharge flow rate Qpt so that the deviation of the actual pump discharge flow rate Qpr from the target pump discharge flow rate Qpt becomes smaller.

[0112] In step S53, the controller 70 calculates a command (pump command) to output to the pump 21. The controller 70 calculates a pump command such that the actual capacity of the pump 21 becomes the target value of the pump 21's capacity calculated in step S52. The pump command is, for example, a current value (command current).

[0113] In step S54, the controller 70 outputs a pump command to the pump capacity control unit 23.

[0114] (Control valve control process) In steps S62 to S64, the controller 70 (specifically the control valve control unit 71d) controls the opening of the control valve 41 based on the actuator target flow rate Qat (see step S23 in Figure 5 and Figure 3).

[0115] In step S62, the controller 70 provides feedback control to the flow rate from the control valve 41 to the actuator 30. Specifically, as described above, the controller 70 obtains the target flow rate for each actuator 30 (see step S22 in Figure 5). The controller 70 also obtains the actual flow rate for each actuator 30 (see step S41 in Figure 6). Then, in step S62, the controller 70 controls the opening of the control valve 41 so that the deviation of the actual flow rate of each actuator 30 from the target flow rate of each actuator 30 is reduced. In this way, the controller 70 compensates for the target flow rate of each actuator 30 (the target flow rate of the control valve 41).

[0116] In step S63, the controller 70 calculates a command (control valve command) to output to the control valve 41. The controller 70 calculates a control valve command such that the actual opening of the control valve 41 becomes the target opening value calculated in step S62. The control valve command is, for example, a current value (command current). If there are multiple actuators 30, the controller 70 calculates a control valve command for each control valve 41 that controls each actuator 30.

[0117] In step S64, the controller 70 outputs a control valve command to the control valve 41. If there are multiple actuators 30, the controller 70 outputs a control valve command to each control valve 41 that controls each actuator 30.

[0118] (Unload valve control process) In steps S73 and S74, the controller 70 (specifically, the unload valve control unit 71c) controls the opening of the unload valve 43 (feedforward control) based on the actuator target flow rate Qat (see step S23 in Figure 5 and Figure 3).

[0119] In step S73, as shown in Figure 4, the controller 70 (specifically, the unload command generation unit 71c3) calculates (generates) an unload command. Specifically, in step S35 (see Figure 5), the controller 70 calculates a target value for the unload flow rate Qu based on the unload state map M (for example, the unload flow rate map Ma), corresponding to the actuator target flow rate Qat. Then, in step S73, the controller 70 calculates an unload command based on the unload command map, corresponding to the target value for the unload flow rate Qu calculated in step S35 (see Figure 5).

[0120] In step S74, the controller 70 outputs an unload command to the unload valve 43.

[0121] The series of processes performed by the controller 70 (steps S11 (see Figure 5) to S74 (see Figure 6)) are repeated. However, processes that only need to be performed once and do not need to be repeated, such as the assignment setting of the unload operation mode (step S11) and the determination of the operating mode (steps S12 to S14n) shown in Figure 5, do not need to be repeated.

[0122] (Effects of the first invention) The effects of the control device 1 shown in Figure 2 are as follows: The control device 1 controls the movement of the work machine 10. The control device 1 comprises a tank 20t, a pump 21, an actuator 30, an unload valve 43, and a controller 70. The tank 20t stores oil. The pump 21 discharges the oil stored in the tank 20t. The actuator 30 is driven by the oil supplied by the pump 21. The unload valve 43 adjusts the flow rate of oil discharged by the pump 21 that flows into the tank 20t without passing through the actuator 30. The controller 70 calculates the actuator target flow rate Qat (see Figure 3), which is the target value of the oil flowing into the actuator 30, based on the amount of operation (actuator operation amount) used to drive the actuator 30. The controller 70 controls the opening of the unload valve 43 based on the actuator target flow rate Qat.

[0123] [Configuration 1] The controller 70 changes the unload fully closed flow rate Qac (see Figure 3) according to the conditions related to the usage status of the work machine 10 and set in the controller 70 (unload fully closed flow rate change conditions). As shown in Figure 3, the unload fully closed flow rate Qac is the minimum value of the actuator target flow rate Qat when the unload valve 43 is fully closed.

[0124] The above [Configuration 1] provides the following effects: When the unload total closing flow rate Qac is increased (changed to a larger value), when the amount of operation to drive the actuator 30 shown in Figure 2 is changed, the sudden closing of the opening of the unload valve 43 is suppressed (the change in opening becomes gentler). Therefore, for example, the operability of the operation to drive the actuator 30 can be improved. Also, when the unload total closing flow rate Qac shown in Figure 3 is decreased (changed to a smaller value), the unload valve 43 closes even if the amount of operation to drive the actuator 30 shown in Figure 2 is small. Therefore, for example, the loss of hydraulic energy output by the pump 21 can be suppressed, and the fuel efficiency of the work machine 10 can be improved. In the above [Configuration 1], the characteristic of fully closing the unload valve 43 can be changed according to the conditions related to the usage of the work machine 10 and set in the controller 70 (unload total closing flow rate change conditions). Therefore, the characteristic of fully closing the unload valve 43 can be set to an appropriate characteristic according to the usage of the work machine 10.

[0125] (Effects of the second invention) [Configuration 2] The controller 70 changes the unloaded fully closed flow rate Qac shown in Figure 3 according to the operating mode, which is the method of operation for driving the actuator 30.

[0126] The following effect can be obtained with the above [Configuration 2]. Depending on the operating mode, the appropriate unload total closed flow rate Qac may differ. Therefore, in the above [Configuration 2], the controller 70 changes the unload total closed flow rate Qac according to the operating mode. Thus, if the relationship (assignment) between the operating mode and the unload total closed flow rate Qac is set appropriately, an appropriate unload total closed flow rate Qac can be set according to the operating mode. Note that even when the unload total closed flow rate Qac is changed based on the operating mode and other unload total closed flow rate change conditions (e.g., work content), this is also included in "changing the unload total closed flow rate Qac according to the operating mode".

[0127] (Effects of the third invention) [Configuration 3] As shown in Figure 1, the control device 1 includes an imaging device 53 that images the inside of the operator's cab 13c of the work machine 10. The controller 70 determines the operating mode based on the image of the inside of the operator's cab 13c captured by the imaging device 53.

[0128] The following effects can be obtained with the above [Configuration 3]. Depending on the operating mode, the conditions inside the operator's chamber 13c may differ. Therefore, in the above [Configuration 3], the controller 70 determines the operating mode based on the image of the inside of the operator's chamber 13c captured by the imaging device 53. Thus, the operating mode can be appropriately determined based on the image of the inside of the operator's chamber 13c (using the information from the image). As a result, an appropriate unload fully closed flow rate Qac (see Figure 3) can be set according to the operating mode (above [Configuration 2]).

[0129] (Effects of the fourth invention) The control device 1 includes an in-cab operating device 61a. The in-cab operating device 61a is located inside the driver's cab 13c and receives input for operations to drive the actuator 30.

[0130] [Configuration 4] The controller 70 determines whether the operating mode is remote operation or not based on whether the remote operation response device 65 is visible in the captured image ([Configuration 3] above). The remote operation response device 65 is a device for operating the operator's cab control device 61a from outside the work machine 10. The controller 70 changes the unload fully closed flow rate Qac (see Figure 3) depending on whether the operating mode is remote operation or not.

[0131] With the above configuration [4], the controller 70 can appropriately determine whether the operating mode is remote operation or not. As a result, the unload fully closed flow rate Qac (see Figure 3) can be appropriately changed depending on whether the operating mode is remote operation or not.

[0132] (Effects of the fifth invention) [Configuration 5] As shown in Figure 2, the control device 1 includes an operating mode setting unit 67 that sets the operating mode according to the operator's operation.

[0133] The above [Configuration 5] allows the operator to reliably set (specify, select) the operating mode. As a result, an appropriate unload fully closed flow rate Qac (see Figure 3) can be set according to the operating mode (as described in [Configuration 2] above).

[0134] (Effects of the sixth invention) [Configuration 6] The control device 1 includes an output unit 80 that outputs information. The controller 70 causes the output unit 80 to output information indicating the state of the unloaded fully closed flow rate Qac (see Figure 3).

[0135] The above [Configuration 6] allows the operator to understand the state of the unload valve fully closed flow rate Qac (see Figure 3) (for example, what the value is, what mode the unload valve is operating in, etc.).

[0136] (modified version) The above embodiments (including variations within the embodiments (hereinafter the same)) may be modified in various ways. For example, the number of components in the above embodiments may be changed, and some components may not be provided. For example, the arrangement of components may be changed. For example, the connections between components shown in Figure 2 may be changed. For example, the inclusion relationships of components may be changed in various ways. For example, a component described as a subordinate component included in a higher-level component may not be included in this higher-level component, but may be included in other components. For example, a group of elements described as distinct from each other may be treated as a single element. For example, a single element may be divided into a group of distinct elements. For example, each component may have only a part of each characteristic (function, arrangement, shape, operation, etc.).

[0137] For example, the order of steps in the flowcharts shown in Figures 5 and 6 may be changed, and some steps may be omitted. For example, various types of information (values, ranges, etc.) may be pre-set in the controller 70 shown in Figure 2, or they may be set by being read into the controller 70 from an external storage device. Various types of information may be set in the controller 70 based on information set by manual operation of the input unit 60 by an operator. Various types of information may be set in the controller 70 based on information detected by the detection unit 50. For example, various types of information may not be changed, may be changed by manual operation, or may be automatically changed by the controller 70 according to some condition. For example, the controller 70 may perform substantially the same processing as the processing (calculation, judgment, etc.) of the above embodiment. For example, the mathematical formulas used in the processing, the processing procedures, and the information used in the processing can be changed in various ways. For example, the controller 70 may perform processing using information that can be converted into the various types of information used in the above embodiment. The processing performed by the controller 70 may be combined in various ways.

[0138] The control device 1 is configured to perform each of the operations described above. A control program may be set to cause the controller 70 (computer) to execute the processes that cause each of the operations described above. A control method may be used to perform each of the operations described above. Each of the operations described above may be referred to as a "step" in the control program and control method described above. For example, changing the unload fully closed flow rate Qac (see Figure 3) may be referred to as the "unload fully closed flow rate change step". [Explanation of Symbols]

[0139] 1. Control device 10 Working Machines 13c Driver's Cab 20t tank 21 pumps 30 Actuators 43 Unload valve 53 Imaging device 61a In-cab operating device 65 Remote operation response device 67 Operating Mode Setting Section 70 Controllers 80 Output section Qac Unload Fully Closed Flow Rate Qat actuator target flow rate

Claims

1. A control device for controlling the movement of a work machine, A tank for storing oil, A pump for discharging the oil stored in the aforementioned tank, An actuator driven by the supply of oil discharged by the aforementioned pump, An unload valve that adjusts the flow rate of oil discharged by the pump and allowed to flow into the tank without passing through the actuator, A controller that calculates an actuator target flow rate, which is a target value for the flow rate of oil into the actuator, based on the amount of operation used to drive the actuator, and controls the opening of the unload valve based on the actuator target flow rate, Equipped with, The controller changes the unloading valve's fully closed flow rate, which is the minimum target flow rate of the actuator when the unloading valve is fully closed, according to conditions related to the usage status of the work machine, which are set in the controller. Control device.

2. A control device according to claim 1, The controller changes the unloaded total closing flow rate according to the operating mode, which is the method of operation for driving the actuator. Control device.

3. A control device according to claim 2, The machine is equipped with an imaging device that captures images of the inside of the operator's cab, The controller determines the operating mode based on the image of the interior of the driver's cab captured by the imaging device. Control device.

4. A control device according to claim 3, The cab is equipped with an in-cab operating device that is located inside the cab and into which the operation to drive the actuator is input, The aforementioned controller, Based on whether or not a remote operation response device, which is a device for operating the control panel in the operator's cab from outside the work machine, is visible in the captured image, it is determined whether or not the operating mode is remote operation. The unloading fully closed flow rate is changed depending on whether the operating mode is remote operation or not. Control device.

5. A control device according to claim 2, It includes an operating mode setting unit that sets the operating mode according to the operator's operation, Control device.

6. A control device according to claim 1, It is equipped with an output unit that outputs information, The controller causes the output unit to output information indicating the state of the unloaded, fully closed flow rate. Control device.

Images