Work machine and remote operation system for work machine

Abstract

To provide a working machine capable of achieving a regeneration function by a simpler hydraulic circuit.SOLUTION: The work machine 100 includes an arm cylinder 8, a main pump 14, a first control valve 8B provided in a first oil passage CD1 connecting the main pump 14 and a bottom-side oil chamber V1 of the arm cylinder 8, and a second control valve 8R provided in a second oil passage CD2 connecting the main pump 14 and a rod-side oil chamber V2 of the arm cylinder 8. Then, the work machine 100 is configured to be able to regenerate the working oil discharged from the rod side oil chamber 8R to the bottom side oil chamber 8B through the second control valve V2 and the first control valve V1.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to work machines and remote operation systems for work machines. [Background technology]

[0002] Conventionally, there is known a construction machine that, when performing a regeneration function of causing hydraulic oil that has flowed out of the rod-side oil chamber of a hydraulic cylinder to flow into the bottom-side oil chamber of the hydraulic cylinder, calculates the differential pressure between the upstream and downstream sides of a regeneration valve located in an oil line that resupplies return oil to a hydraulic actuator, and can control the opening of the regeneration valve based on the calculated differential pressure (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-74433 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned construction machine may have a complicated hydraulic circuit.

[0005] Therefore, it is desirable to provide a work machine that can achieve the regeneration function with a simpler hydraulic circuit. [Means for solving the problem]

[0006] A work machine according to an embodiment of the present disclosure comprises a lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, an attachment attached to the upper rotating body, a hydraulic cylinder that moves the attachment, a hydraulic pump mounted on the upper rotating body, a first control valve provided in a first oil passage connecting the hydraulic pump and an oil chamber on one end of the hydraulic cylinder, and a second control valve provided in a second oil passage connecting the hydraulic pump and an oil chamber on the other end of the hydraulic cylinder, and is configured so that hydraulic oil discharged from the oil chamber on the other end can be recycled to the hydraulic cylinder via the second control valve and the first control valve. [Effects of the Invention]

[0007] The above-described work machine can achieve the regeneration function with a simpler hydraulic circuit. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram illustrating an example of a remote system for a work machine according to an embodiment of the present disclosure. [Figure 2] 1 is a side view of a work machine according to an embodiment of the present disclosure; FIG. [Figure 3] FIG. 1 is a diagram illustrating an example configuration of a drive control system of a work machine according to an embodiment of the present disclosure. [Figure 4] FIG. 2 is a diagram illustrating an example configuration of a controller mounted on a work machine according to an embodiment of the present disclosure. [Figure 5] FIG. 5 is a diagram illustrating a control method of the controller shown in FIG. [Figure 6] FIG. 10 is a diagram showing the state of the arm hydraulic circuit when high-output arm closing is being performed. [Figure 7] FIG. 10 is a diagram showing a state of the arm hydraulic circuit when the arm is being opened. [Figure 8] FIG. 10 is a diagram showing the state of the arm hydraulic circuit when high-speed arm closing is being performed. [Figure 9] 5 is a diagram illustrating another control method of the controller shown in FIG. 4. FIG. [Figure 10]5 is a diagram illustrating yet another control method of the controller shown in FIG. 4. FIG. [Figure 11] 5 is a diagram illustrating yet another control method of the controller shown in FIG. 4. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The embodiments described below are merely examples and do not limit the invention, and all features and combinations described in the embodiments are not necessarily essential to the invention. In addition, identical or corresponding components in each drawing are designated by identical or corresponding reference numerals, and descriptions thereof may be omitted.

[0010] First, an overview of a remote control system SYS for a work machine according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram showing an example of a remote control system SYS for a work machine.

[0011] <Devices that make up the work machine system> 1, the remote operation system SYS for a work machine includes a work machine 100 and a remote operation room RC. The work machine 100 and the remote operation room RC are connected via a communication line NW so that data can be sent and received.

[0012] This enables wireless communication of the work machine 100. The work machine 100 is then able to send and receive data to and from equipment (for example, a remote control room RC) connected to the communication line NW.

[0013] The work machine 100 can then transmit information regarding the work site to the remote control room RC. This allows the remote control room RC to check the work site in accordance with the information from the work machine 100. Note that the device that measures the work site is not limited to the work machine 100, and may be other types of device such as a drone that flies over the work site, a fixed camera, or an imaging device that can be carried by the user.

[0014] For example, an imaging device S6 (see FIG. 2) is provided on the work machine 100. The work machine 100 transmits imaging information indicating the results of imaging the work site by the imaging device S6 to the remote control room RC.

[0015] The remote operation system SYS for a work machine may include one or more work machines 100. This allows the remote operation system SYS for a work machine to provide information about the work site to the remote control room RC through the multiple work machines 100.

[0016] <Example of remote control room configuration> The remote control room RC is equipped with a communication device T2, a remote controller 40, an operation device 42, an operation sensor 43, a display device D1, and a speaker A2. The remote control room RC also has an operation seat DS where a remote operator OP who remotely operates the work machine 100 sits.

[0017] The communication device T2 is configured to control communication with the communication device T1 (see FIG. 2) attached to the work machine 100.

[0018] The remote controller 40 is a control device that executes various calculations. In the illustrated example, the remote controller 40 is configured with a microcomputer including a CPU, memory, and nonvolatile storage device. The various functions of the remote controller 40 are realized by the CPU executing programs stored in the memory.

[0019] The display device D1 displays a screen based on information transmitted from the work machine 100 so that the remote operator OP in the remote control room RC can visually confirm the surroundings of the work machine 100. The display device D1 enables the remote operator OP to check the status of the work site including the surroundings of the work machine 100, even though he is in the remote control room RC. In the illustrated example, the display device D1 is a liquid crystal display, but it may also be XR (augmented reality) goggles or the like.

[0020] The operation device 42 is a device used by the remote operator OP to operate the actuators. The actuators include at least one of a hydraulic actuator and an electric actuator. In the illustrated example, the operation device 42 includes an operation lever, a travel lever, and a travel pedal. The operation lever includes a left operation lever for swing operation and arm operation, and a right operation lever for boom operation and bucket operation. Note that, hereinafter, the left operation lever will be referred to as a swing operation lever when used for swing operation, and as an arm operation lever when used for arm operation. Furthermore, the right operation lever will be referred to as a boom operation lever when used for boom operation, and as a bucket operation lever when used for bucket operation.

[0021] An operation sensor 43 is installed in the operation device 42 (an example of an operation unit) to detect the operation content of the operation device 42. The operation sensor 43 is, for example, an inclination sensor that detects the inclination angle of the operation lever, or an angle sensor that detects the swing angle of the operation lever about the swing axis. The operation sensor 43 may be configured with other sensors such as a pressure sensor, a current sensor, a voltage sensor, or a distance sensor. The operation sensor 43 outputs information related to the detected operation content of the operation device 42 to the remote controller 40. The remote controller 40 generates an operation signal based on the received information and transmits the generated operation signal to the work machine 100. The operation sensor 43 may be configured to generate an operation signal. In this case, the operation sensor 43 may output the operation signal to the communication device T2 without going through the remote controller 40. This makes it possible to remotely operate the work machine 100 from the remote control room RC.

[0022] The speaker A2 outputs sound information transmitted from the work machine 100 so that the remote operator OP in the remote control room RC can recognize sounds occurring around the work machine 100.

[0023] <Example of work machine configuration> Next, an overview of the work machine 100 will be described with reference to Figure 2. Figure 2 is a side view of a shovel (excavator), which is an example of the work machine 100. The work machine 100 may be a crane. An upper rotating body 3 is rotatably mounted on a lower traveling body 1 of the work machine 100 via a rotating mechanism 2. A boom 4 is attached to the upper rotating body 3. An arm 5 is attached to the tip of the boom 4, and a bucket 6 is attached to the tip of the arm 5 as an end attachment. The end attachment may be a slope bucket, a dredging bucket, or the like.

[0024] In the example shown in FIG. 2, the direction of travel (front-to-rear direction) of the work machine 100 is indicated by the X axis, the width direction of the work machine 100 is indicated by the Y axis, and the height direction of the work machine 100 is indicated by the Z axis.

[0025] The boom 4, arm 5, and bucket 6 constitute an excavation attachment, which is an example of an attachment AT, and are hydraulically driven by a boom cylinder 7, an arm cylinder 8, and a bucket cylinder 9, each of which serves as a hydraulic cylinder HC. A boom angle sensor S1 is attached to the boom 4, an arm angle sensor S2 is attached to the arm 5, and a bucket angle sensor S3 is attached to the bucket 6.

[0026] The boom angle sensor S1 detects the rotation angle of the boom 4. In this embodiment, the boom angle sensor S1 is an acceleration sensor, and can detect the boom angle, which is the rotation angle of the boom 4 relative to the upper rotating body 3. For example, the boom angle is at its minimum when the boom 4 is lowered to the lowest position, and increases as the boom 4 is raised.

[0027] The arm angle sensor S2 detects the rotation angle of the arm 5. In this embodiment, the arm angle sensor S2 is an acceleration sensor, and can detect the arm angle, which is the rotation angle of the arm 5 relative to the boom 4. For example, the arm angle is at its smallest when the arm 5 is fully closed, and increases as the arm 5 opens.

[0028] The bucket angle sensor S3 detects the rotation angle of the bucket 6. In this embodiment, the bucket angle sensor S3 is an acceleration sensor, and can detect the bucket angle, which is the rotation angle of the bucket 6 with respect to the arm 5. For example, the bucket angle is at its smallest when the bucket 6 is fully closed, and increases as the bucket 6 opens.

[0029] The boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 may be a potentiometer using a variable resistor, a stroke sensor that detects the stroke amount of the corresponding hydraulic cylinder HC, or a rotary encoder that detects the rotation angle around the connecting pin. The boom angle sensor S1, arm angle sensor S2, and bucket angle sensor S3 form a posture sensor that detects the posture of the excavation attachment.

[0030] The boom bottom pressure sensor S7B is a pressure sensor for detecting boom bottom pressure, which is the pressure of hydraulic oil in the bottom-side oil chamber of the boom cylinder 7. The boom rod pressure sensor S7R is a pressure sensor for detecting boom rod pressure, which is the pressure of hydraulic oil in the rod-side oil chamber of the boom cylinder 7. The arm bottom pressure sensor S8B is a pressure sensor for detecting arm bottom pressure, which is the pressure of hydraulic oil in the bottom-side oil chamber of the arm cylinder 8. The arm rod pressure sensor S8R is a pressure sensor for detecting arm rod pressure, which is the pressure of hydraulic oil in the rod-side oil chamber of the arm cylinder 8. The bucket bottom pressure sensor S9B is a pressure sensor for detecting bucket bottom pressure, which is the pressure of hydraulic oil in the bottom-side oil chamber of the bucket cylinder 9. The bucket rod pressure sensor S9R is a pressure sensor for detecting bucket rod pressure, which is the pressure of hydraulic oil in the rod-side oil chamber of the bucket cylinder 9. In the illustrated example, the boom bottom pressure sensor S7B is provided in an oil passage connecting the bottom-side oil chamber of the boom cylinder 7 and the control valve unit 17, but it may be provided in the boom cylinder 7. The same applies to the boom rod pressure sensor S7R, the arm bottom pressure sensor S8B, the arm rod pressure sensor S8R, the bucket bottom pressure sensor S9B, and the bucket rod pressure sensor S9R.

[0031] The upper rotating body 3 is equipped with a cabin 10 as a driver's cab, an engine 11, a body tilt sensor S4, a turning angular velocity sensor S5, an imaging device S6, a positioning device PD, a microphone array A1, a communication device T1, and the like.

[0032] A controller 30 is installed inside the cabin 10. Also installed inside the cabin 10 are a driver's seat, operating devices, and the like.

[0033] The controller 30 is a control device that executes various calculations. The controller 30 is provided, for example, inside the cabin 10, and controls the drive of the work machine 100. The functions of the controller 30 may be realized by any hardware, software, or a combination thereof. For example, the controller 30 is configured mainly with a microcomputer that includes a CPU, memory such as RAM, a non-volatile storage device such as ROM, and various interface devices for input and output. The controller 30 realizes various functions, for example, by executing, on the CPU, various programs installed in the non-volatile storage device.

[0034] The engine 11 is the drive source of the work machine 100. In this embodiment, the engine 11 is a diesel engine, and is mounted at the rear of the upper rotating body 3. The output shaft of the engine 11 is connected to the input shafts of the main pump 14 and the pilot pump 15. Specifically, the engine 11 rotates at a constant speed at a preset target rotation speed under direct or indirect control by the controller 30, and drives the main pump 14 and the pilot pump 15. Note that the drive source of the work machine 100 may also be a battery-powered electric motor. In other words, the work machine 100 may be a hybrid work machine or an electric work machine.

[0035] The machine body tilt sensor S4 is configured to detect the tilt of the upper rotating body 3 with respect to a predetermined plane. In this embodiment, the machine body tilt sensor S4 is an acceleration sensor that detects the tilt angle about the longitudinal axis and the lateral axis of the upper rotating body 3 with respect to a horizontal plane. The longitudinal axis and the lateral axis of the upper rotating body 3 are, for example, perpendicular to each other and pass through a center point that is a point on the rotation axis of the work machine 100.

[0036] The rotation angular velocity sensor S5 is configured to detect the rotation angular velocity of the upper rotating body 3. In this embodiment, the rotation angular velocity sensor S5 is a gyro sensor. The rotation angular velocity sensor S5 may be a resolver, a rotary encoder, or the like. The rotation angular velocity sensor S5 may detect a rotation speed. The rotation speed may be calculated from the rotation angular velocity.

[0037] The imaging device S6 is configured to acquire images of the periphery of the work machine 100. In this embodiment, the imaging device S6 includes a front camera S6F that images the space in front of the work machine 100, a left camera S6L that images the space to the left of the work machine 100, a right camera S6R that images the space to the right of the work machine 100, and a rear camera S6B that images the space behind the work machine 100.

[0038] The image capturing device S6 may be, for example, a monocular camera having an image capturing element such as a CCD or CMOS, and may output the captured image to the display device D2.

[0039] The front camera S6F is attached, for example, to the roof of the cabin 10. The left camera S6L is attached to the left end of the upper surface of the upper rotating body 3. The right camera S6R is attached to the right end of the upper surface of the upper rotating body 3. The rear camera S6B is attached to the rear end of the upper surface of the upper rotating body 3.

[0040] In this embodiment, by arranging the imaging device S6 in the above-described manner, it is possible to capture images of objects present around the work machine 100. Note that the imaging device S6 may be a camera that can recognize the distance to the object being photographed (for example, an RGBD camera or a stereo camera).

[0041] The positioning device PD is configured to acquire information related to the position of the work machine 100. In this embodiment, the positioning device PD is configured to measure the position and orientation of the work machine 100 in a reference coordinate system. Specifically, the positioning device PD is a GNSS receiver with an integrated electronic compass, and measures the latitude, longitude, and altitude of the current position of the work machine 100, and also measures the orientation of the work machine 100. The reference coordinate system according to this embodiment is, for example, the World Geodetic System. The World Geodetic System is a three-dimensional orthogonal XYZ coordinate system with its origin at the center of gravity of the Earth, its X axis pointing in the direction of the intersection of the Greenwich meridian and the equator, its Y axis pointing in the direction of 90 degrees east longitude, and its Z axis pointing in the direction of the North Pole.

[0042] The communication device T1 is configured to control communications with devices external to the work machine 100. In this embodiment, the communication device T1 is configured to control communications between the communication device T1 and devices external to the work machine 100 via a wireless communication network. The communication device T1 includes, for example, a mobile communication module compatible with mobile communication standards such as LTE (Long Term Evolution), 4G (4th Generation), and 5G (5th Generation), a satellite communication module for connecting to a satellite communication network, and the like.

[0043] Furthermore, the communication device T1 controls wireless communication between the work machine 100 and an external GNSS (Global Navigation Satellite System) surveying system, for example.

[0044] The microphone array A1 has a plurality of microphones and is configured to collect sounds generated around the work machine 100. In this embodiment, the microphone array A1 is a plurality of microphones attached to the upper rotating body 3.

[0045] [Work machine drive control system] Figure 3 is a diagram showing an example of the configuration of a drive control system of the work machine 100 of Figure 2. In Figure 3, the mechanical power transmission system is indicated by double lines, the hydraulic oil lines are indicated by thick solid lines, the pilot lines are indicated by dashed lines, and the electric drive and control system is indicated by dotted lines.

[0046] The drive system of the work machine 100 according to this embodiment includes the engine 11, regulator 13, main pump 14, and control valve unit 17. Furthermore, the hydraulic drive system of the work machine 100 according to this embodiment includes hydraulic actuators such as the travel hydraulic motors (left travel hydraulic motor 1L and right travel hydraulic motor 1R) that hydraulically drive the lower traveling body 1, upper rotating body 3, boom 4, arm 5, and bucket 6, respectively, the swing hydraulic motor 2A, the boom cylinder 7, the arm cylinder 8, and the bucket cylinder 9, as described above.

[0047] The regulator 13 controls the discharge amount of the main pump 14. For example, the regulator 13 adjusts the angle (tilt angle) of the swash plate of the main pump 14 in response to a control command from the controller 30.

[0048] The main pump 14 is mounted, for example, on the rear of the upper rotating body 3, similar to the engine 11, and supplies hydraulic oil to the control valve unit 17 through a high-pressure hydraulic line. 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, thereby adjusting the stroke length of the piston and controlling the discharge flow rate (discharge pressure).

[0049] The control valve unit 17 is a hydraulic control device that controls the hydraulic system of the work machine 100. In this embodiment, the control valve unit 17 includes control valves 171-176 that serve as spool valves. The control valve unit 17 is configured to selectively supply hydraulic oil discharged by the main pump 14 to one or more hydraulic actuators via the control valves 171-176. The control valves 171-176 control, for example, the flow rate of hydraulic oil flowing from the main pump 14 to the hydraulic actuators and the flow rate of hydraulic oil flowing from the hydraulic actuators to a hydraulic oil tank. The hydraulic actuators include a boom cylinder 7, an arm cylinder 8, a bucket cylinder 9, a left traveling hydraulic motor 1L, a right traveling hydraulic motor 1R, and a swing hydraulic motor 2A. More specifically, the control valve 171 corresponds to the left traveling hydraulic motor 1L, the control valve 172 corresponds to the right traveling hydraulic motor 1R, and the control valve 173 corresponds to the swing hydraulic motor 2A. Furthermore, the control valve 174 corresponds to the bucket cylinder 9 , the control valve 175 corresponds to the boom cylinder 7 , and the control valve 176 corresponds to the arm cylinder 8 .

[0050] The pilot pump 15 is an example of a pilot pressure generating device, and is configured to supply hydraulic oil to hydraulic control devices via a pilot line. In this embodiment, the pilot pump 15 is a fixed displacement hydraulic pump. However, the pilot pressure generating device may be realized by the main pump 14. That is, the main pump 14 may have a function of supplying hydraulic oil to various hydraulic control devices via a pilot line, in addition to a function of supplying hydraulic oil to the control valve unit 17 via a hydraulic oil line. In this case, the pilot pump 15 may be omitted.

[0051] The control device 26 is a device used by an operator in the cabin 10 to operate the actuators. The actuators include at least one of a hydraulic actuator and an electric actuator. In the illustrated example, the control device 26 includes a control lever, a travel lever, and a travel pedal, similar to the control device 42. The control lever includes a left control lever for swing operation and arm operation, and a right control lever for boom operation and bucket operation.

[0052] The discharge pressure sensor 28 is configured to detect the discharge pressure of the main pump 14. In this embodiment, the discharge pressure sensor 28 outputs the detected value to the controller 30.

[0053] The operation sensor 29 is configured to detect the operation content of the operator using the operation device 26. In this embodiment, the operation sensor 29 detects the operation direction and operation amount of the operation device 26 corresponding to each actuator and outputs the detected values ​​to the controller 30. In this embodiment, the controller 30 controls the opening area of ​​the solenoid valve 31 in accordance with the output of the operation sensor 29. The controller 30 then supplies the hydraulic oil discharged from the pilot pump 15 to the pilot ports of the corresponding control valves in the control valve unit 17. The pressure of the hydraulic oil supplied to each pilot port (pilot pressure) is, in principle, a pressure corresponding to the operation direction and operation amount of the operation device 26 corresponding to each hydraulic actuator. In this way, the operation device 26 is configured to supply the hydraulic oil discharged from the pilot pump 15 to the pilot ports of the corresponding control valves in the control valve unit 17.

[0054] The solenoid valve 31, which functions as a control valve for machine control, is disposed in an oil passage connecting the pilot pump 15 and the pilot port of the control valve in the control valve unit 17, and is configured to be able to change the flow path area of ​​that oil passage. In this embodiment, the solenoid valve 31 operates in response to a control command output by the controller 30. Therefore, the controller 30 can supply the hydraulic oil discharged by the pilot pump 15 to the pilot port of the control valve in the control valve unit 17 via the solenoid valve 31, regardless of the operation of the operating device 26 by the operator.

[0055] With this configuration, the controller 30 can operate the hydraulic actuator corresponding to a specific operating device 26 even when the specific operating device 26 is not being operated.

[0056] For example, the controller 30 sets a target rotation speed based on a work mode or the like that is set in advance by a predetermined operation by an operator or the like, and performs drive control to rotate the engine 11 at a constant speed.

[0057] Furthermore, for example, the controller 30 outputs a control command to the regulator 13 as necessary to change the discharge rate of the main pump 14.

[0058] Furthermore, for example, the controller 30 performs control relating to a machine guidance function that guides (provides guidance for) the manual operation of the work machine 100 by the operator via the operation device 26. Furthermore, the controller 30 performs control relating to a machine control function that automatically assists the manual operation of the work machine 100 by the operator via the operation device 26.

[0059] Note that some of the functions of the controller 30 may be realized by another controller (control device). That is, the functions of the controller 30 may be realized in a distributed manner by a plurality of controllers. For example, the machine guidance function and the machine control function may be realized by a dedicated controller (control device).

[0060] Next, with reference to Figs. 4 to 8, an example configuration of the controller 30 that controls the movement of the arm cylinder 8 will be described. Fig. 4 is a block diagram showing an example configuration of the controller 30 that controls the movement of the arm cylinder 8. Fig. 5 is a diagram explaining a control method of the controller 30 that controls the movement of the arm cylinder 8. Figs. 6 to 8 are diagrams showing an example configuration of an arm hydraulic circuit that is a hydraulic circuit related to the arm cylinder 8. Specifically, Fig. 6 shows the state of the arm hydraulic circuit when the arm 5 is closed without using the regeneration function, Fig. 7 shows the state of the arm hydraulic circuit when the arm 5 is opened without using the regeneration function, and Fig. 8 shows the state of the arm hydraulic circuit when the arm 5 is closed using the regeneration function. Here, the regeneration function means a function of returning hydraulic oil flowing out from one oil chamber of the hydraulic cylinder HC (rod-side oil chamber 8R of the arm cylinder 8) to the other oil chamber of the hydraulic cylinder HC (bottom-side oil chamber 8B of the arm cylinder 8). 6 also shows that the pressure-receiving area of ​​the piston in contact with the hydraulic oil in the bottom-side oil chamber 8B of the arm cylinder 8 (bottom-side pressure-receiving area) is value A1, and the pressure-receiving area of ​​the piston in contact with the hydraulic oil in the rod-side oil chamber 8R of the arm cylinder 8 (rod-side pressure-receiving area) is value A2 (>value A1). Note that the following explanation with reference to FIGS. 4 to 8 relates to the movement of the arm cylinder 8, but is similarly applicable to the movement of other single-rod hydraulic cylinders such as the bucket cylinder 9.

[0061] 4, the controller 30 is configured to receive outputs from the arm bottom pressure sensor S8B, the arm rod pressure sensor S8R, the discharge pressure sensor 28, and the operation sensor 29, execute various calculations, and output control commands to the solenoid valve 31. In the case of remote control, the operation sensor 29 is replaced with an operation sensor 43.

[0062] The solenoid valve 31 is configured to be able to control the pilot pressure acting on the pilot port of the control valve 176 corresponding to the arm cylinder 8. Specifically, as shown in Fig. 6, the control valve 176 includes a first arm control valve 176A serving as the first control valve V1 and a second arm control valve 176B serving as the second control valve V2. The solenoid valve 31 includes a first arm solenoid valve 31A corresponding to the first arm control valve 176A and a second arm solenoid valve 31B corresponding to the second arm control valve 176B.

[0063] The first arm control valve 176A is provided in a first oil passage CD1 that connects the main pump 14 and the bottom-side oil chamber 8B of the arm cylinder 8. The first oil passage CD1 includes a first portion CD11 that connects the first arm control valve 176A and the bottom-side oil chamber 8B of the arm cylinder 8, and a second portion CD12 that connects the first arm control valve 176A and the main pump 14. In the illustrated example, the first arm control valve 176A is a spool valve that can move within a spool hole formed in a valve block of the control valve unit 17, and has a first PC port that connects the first portion CD11 and the second portion CD12, and a first CT port that connects the first portion CD11 and a third oil passage CD3. The third oil passage CD3 is an oil passage that connects the first arm control valve 176A and the hydraulic oil tank HT. Note that "P" in the first PC port refers to the hydraulic pump (main pump 14), and "C" in the first PC port refers to the arm cylinder 8. Also, "C" in the first CT port refers to the arm cylinder 8, and "T" in the first CT port refers to the hydraulic oil tank HT. The same applies to the second PC port and second CT port described below.

[0064] In addition, the first arm control valve 176A is configured to be in a first inflow state (the state shown in Figures 6 and 8) that connects the main pump 14 to the bottom-side oil chamber 8B and blocks communication between the bottom-side oil chamber 8B and the hydraulic oil tank HT, a first outflow state (the state shown in Figure 7) that blocks communication between the main pump 14 and the bottom-side oil chamber 8B and connects the bottom-side oil chamber 8B and the hydraulic oil tank HT, or a first neutral state (not shown) that blocks communication between the main pump 14 and the bottom-side oil chamber 8B and blocks communication between the bottom-side oil chamber 8B and the hydraulic oil tank HT.

[0065] 6 to 8, first arm control valve 176A actually has a right pilot port in addition to the left pilot port. First arm control valve 176A is typically configured to move leftward to enter a first inflow state when effective pilot pressure acts on the right pilot port, to move rightward to enter a first outflow state when effective pilot pressure acts on the left pilot port, and to enter a first neutral state by the repulsive force of a compression coil spring or the like when effective pilot pressure is not acting on either the left pilot port or the right pilot port.

[0066] In addition, the first arm control valve 176A is configured such that in the first inflow state, the flow path area of ​​the first PC port increases as it moves to the left, and in the first outflow state, the flow path area of ​​the first CT port increases as it moves to the right.

[0067] The second arm control valve 176B is provided in a second oil passage CD2 that connects the main pump 14 and the rod-side oil chamber 8R of the arm cylinder 8. The second oil passage CD2 includes a first portion CD21 that connects the second arm control valve 176B and the rod-side oil chamber 8R of the arm cylinder 8, and a second portion CD22 that connects the second arm control valve 176B and the main pump 14. In the illustrated example, the second portion CD22 of the second oil passage CD2 is connected to the second portion CD12 of the first oil passage CD1 at a junction JC. The second arm control valve 176B is a spool valve that can move within a spool hole formed in a valve block of the control valve unit 17, and has a second PC port that connects the first portion CD21 and the second portion CD22, and a second CT port that connects the first portion CD21 and the fourth oil passage CD4. The fourth oil passage CD4 is an oil passage that connects the second arm control valve 176B and the hydraulic oil tank HT.

[0068] In addition, the second arm control valve 176B is configured to be in a second outflow state (state shown in Figure 6) in which communication between the main pump 14 and the rod side oil chamber 8R is blocked and communication between the rod side oil chamber 8R and the hydraulic oil tank HT is established; a second inflow state (state shown in Figure 7) in which communication between the main pump 14 and the rod side oil chamber 8R is established and communication between the rod side oil chamber 8R and the hydraulic oil tank HT is blocked; a regeneration state (state shown in Figure 8) in which communication between the rod side oil chamber 8R and the main pump 14 is established and communication between the rod side oil chamber 8R and the hydraulic oil tank HT is blocked; or a second neutral state (not shown) in which communication between the main pump 14 and the rod side oil chamber 8R is blocked and communication between the rod side oil chamber 8R and the hydraulic oil tank HT is blocked.

[0069] 6 to 8, second arm control valve 176B actually has a right pilot port in addition to the left pilot port. Second arm control valve 176B is typically configured to move leftward to enter a second inflow state or regeneration state when valid pilot pressure acts on the right pilot port, to move rightward to enter a second outflow state when valid pilot pressure acts on the left pilot port, and to enter a second neutral state by the repulsive force of a compression coil spring or the like when valid pilot pressure acts on neither the left pilot port nor the right pilot port.

[0070] In addition, the second arm control valve 176B is configured such that in the second inflow state, the flow path area of ​​the first PC port increases as it moves to the left, and in the second outflow state, the flow path area of ​​the second CT port increases as it moves to the right.

[0071] In the illustrated example, the first arm control valve 176A and the second arm control valve 176B are configured to have the same size and shape, i.e., to be the same part, but they may be configured to have different sizes or different shapes.

[0072] Furthermore, the first arm control valve 176A and the second arm control valve 176B may be configured to be fitted into the same spool hole formed in the valve block, or may be configured to be fitted separately into two independent spool holes formed in the valve block.

[0073] The first-arm solenoid valve 31A is configured to be able to adjust the pilot pressure acting on the pilot port of the first-arm control valve 176A. In the illustrated example, the first-arm solenoid valve 31A is basically configured to be able to adjust the pilot pressure acting on each of the left and right pilot ports of the first-arm control valve 176A in accordance with the operation of the operation device 26 (left operation lever). In addition, the first-arm solenoid valve 31A is configured to be able to adjust the pilot pressure acting on each of the left and right pilot ports of the first-arm control valve 176A, as necessary, regardless of the operation of the operation device 26 (left operation lever).

[0074] Similarly, the second-arm solenoid valve 31B is configured to be able to adjust the pilot pressure acting on the pilot port of the second-arm control valve 176B. In the illustrated example, the second-arm solenoid valve 31B is basically configured to be able to adjust the pilot pressure acting on each of the left and right pilot ports of the second-arm control valve 176B in accordance with the operation of the operation device 26 (left operation lever). In addition, the second-arm solenoid valve 31B is configured to be able to adjust the pilot pressure acting on each of the left and right pilot ports of the second-arm control valve 176B as necessary, regardless of the operation of the operation device 26 (left operation lever).

[0075] For example, when the operating device 26 (left operating lever) is operated in the arm closing direction, the controller 30 calculates the cylinder thrust of the arm cylinder 8. Specifically, as shown in Fig. 5, the controller 30 calculates a bottom-side receiving pressure F1 in a first processing unit PU1 by multiplying the arm bottom pressure P1 detected by the arm bottom pressure sensor S8B by the value A1 of the bottom-side pressure receiving area, and calculates a rod-side receiving pressure F2 in a second processing unit PU2 by multiplying the arm rod pressure P2 detected by the arm rod pressure sensor S8R by the value A2 of the rod-side pressure receiving area. Thereafter, the controller 30 calculates the cylinder thrust in a third processing unit PU3 by subtracting the rod-side receiving pressure F2 from the bottom-side receiving pressure F1. Here, the cylinder thrust is a cylinder thrust that attempts to extend the arm cylinder 8 and has a positive value.

[0076] Furthermore, the controller 30, in a fourth processing unit PU4, derives a flow rate command based on a lever operation signal output by the operating device 26 (left operating lever). In the illustrated example, when the operating device 26 (left operating lever) is operated in the arm closing direction, the lever operation signal has a positive value, and the greater the lever operation amount, the greater the value. The flow rate command includes a flow rate command related to the target flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A, i.e., the target flow rate of hydraulic oil flowing into the bottom-side oil chamber 8B of the arm cylinder 8, and a flow rate command related to the target flow rate of hydraulic oil passing through the second PC port of the second arm control valve 176B, i.e., the target flow rate of hydraulic oil flowing out of the rod-side oil chamber 8R of the arm cylinder 8. The greater the value of the lever operation signal, the greater the value of the flow rate command.

[0077] Thereafter, the controller 30 causes the fifth processing unit PU5 to output a value obtained by multiplying the flow rate command by the integral gain Ki to the sixth processing unit PU6. The sixth processing unit PU6 is configured to function as a switch that switches the control content between high-power arm closing and high-speed arm closing. High-power arm closing is performed, for example, when closing the arms to excavate the ground, and high-speed arm closing is performed, for example, when closing the arms by gravity descending in the air.

[0078] Specifically, the controller 30 determines in the sixth processing unit PU6 whether or not the cylinder thrust that attempts to extend the arm cylinder 8 exceeds a predetermined value. If the controller 30 determines that the cylinder thrust exceeds the predetermined value, it executes control details for performing high-power arm closing, and if it determines that the cylinder thrust does not exceed the predetermined value, it executes control details for performing high-speed arm closing. The predetermined value may be zero. If the predetermined value is zero, "when the cylinder thrust does not exceed the predetermined value" means when the direction of the cylinder thrust is opposite to the direction of extension of the arm cylinder 8, and includes, for example, "when performing arm closing by descending by its own weight in the air."

[0079] In the control content when performing high-power arm closing, the controller 30 executes PC flow rate control of the first arm control valve 176A in the seventh processing unit PU7, and executes P2 pressure control of the second arm control valve 176B in the eighth processing unit PU8. "PC flow rate control" refers to control of the PC flow rate (the flow rate of hydraulic oil flowing from the main pump 14 toward the arm cylinder 8). Note that the controller 30 does not execute the regeneration function when performing high-power arm closing.

[0080] In the PC flow rate control of the first arm control valve 176A, the controller 30 moves the first arm control valve 176A so that the flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A becomes a target flow rate. More specifically, the controller 30 outputs a current command to the first arm solenoid valve 31A to adjust the pilot pressure acting on the right pilot port of the first arm control valve 176A, thereby adjusting the flow path area of ​​the first PC port of the first arm control valve 176A, thereby increasing or decreasing the flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A. Note that in the PC flow rate control of the first arm control valve 176A, the controller 30 calculates the flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A based on the difference between the pressure of hydraulic oil on the upstream side of the first PC port (pump discharge pressure PS detected by the discharge pressure sensor 28) and the pressure of hydraulic oil on the downstream side of the first PC port (arm bottom pressure P1 detected by the arm bottom pressure sensor S8B).

[0081] Furthermore, in the P2 pressure control of the second arm control valve 176B, the controller 30 moves the second arm control valve 176B so that the arm rod pressure P2 becomes a predetermined pressure (zero in the illustrated example). More specifically, the controller 30 outputs a current command to the second arm solenoid valve 31B to adjust the pilot pressure acting on the left pilot port of the second arm control valve 176B and adjust the size of the flow path area of ​​the second CT port of the second arm control valve 176B, thereby increasing or decreasing the flow rate of hydraulic oil passing through the second CT port of the second arm control valve 176B, and thereby increasing or decreasing the arm rod pressure P2. Typically, when the arm rod pressure P2 exceeds the predetermined pressure, the controller 30 moves the second arm control valve 176B so that the flow path area of ​​the second CT port of the second arm control valve 176B becomes larger.

[0082] As a result, the controller 30 can perform high-power arm closure while matching the flow rate Q1 of the hydraulic oil flowing through the first portion CD11 of the first oil passage CD1 to the target flow rate and maintaining the arm rod pressure P2 at a predetermined pressure, as shown in Figure 6.

[0083] Furthermore, in the control content when performing high-speed arm closing, the controller 30 executes P1 pressure control of the first arm control valve 176A in a ninth processing unit PU9, and executes CP flow rate control of the second arm control valve 176B in a tenth processing unit PU10. "CP flow rate control" means control of the CP flow rate (the flow rate of hydraulic oil flowing from the arm cylinder 8 toward the main pump 14), and executing the CP flow rate control means executing the regeneration function.

[0084] In the P1 pressure control of the first arm control valve 176A, the controller 30 moves the first arm control valve 176A so that the arm bottom pressure P1 becomes a predetermined pressure (zero in the illustrated example). More specifically, the controller 30 outputs a current command to the first arm solenoid valve 31A to adjust the pilot pressure acting on the right pilot port of the first arm control valve 176A and adjust the size of the flow path area of ​​the first PC port of the first arm control valve 176A, thereby increasing or decreasing the flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A and increasing or decreasing the arm bottom pressure P1. Typically, when the arm bottom pressure P1 exceeds the predetermined pressure, the controller 30 moves the second arm control valve 176B so that the flow path area of ​​the first PC port of the first arm control valve 176A becomes smaller.

[0085] Furthermore, in the CP flow rate control of the second arm control valve 176B, the controller 30 moves the second arm control valve 176B so that the flow rate of the hydraulic oil passing through the second PC port of the second arm control valve 176B becomes the target flow rate. More specifically, the controller 30 outputs a current command to the second arm solenoid valve 31B to adjust the pilot pressure acting on the right pilot port of the second arm control valve 176B, thereby adjusting the size of the flow path area of ​​the second PC port of the second arm control valve 176B, thereby increasing or decreasing the flow rate of the hydraulic oil passing through the second PC port of the second arm control valve 176B. In addition, in the CP flow rate control of the second arm control valve 176B, the controller 30 calculates the flow rate of the hydraulic oil passing through the second PC port of the second arm control valve 176B based on the difference between the pressure of the hydraulic oil on the upstream side of the second PC port (the arm rod pressure P2 detected by the arm rod pressure sensor S8R) and the pressure of the hydraulic oil on the downstream side of the second PC port (the pump discharge pressure PS detected by the discharge pressure sensor 28).

[0086] As a result, the controller 30 can perform high-speed arm closure while matching the flow rate Q2 of the hydraulic oil flowing through the first portion CD21 of the second oil passage CD2 to the target flow rate and maintaining the arm bottom pressure P1 at a predetermined pressure, as shown in Figure 8.

[0087] On the other hand, when the operating device 26 (left operating lever) is operated in the arm opening direction, the controller 30 causes the eleventh processing unit PU11 to derive a flow rate command based on the lever operation signal output by the operating device 26 (left operating lever). In the illustrated example, when the operating device 26 (left operating lever) is operated in the arm opening direction, the lever operation signal has a negative value, and the larger the lever operation amount, the smaller the value (larger the absolute value) of the lever operation signal. The flow rate command also includes a flow rate command related to the target flow rate of hydraulic oil passing through the second PC port of the second arm control valve 176B, i.e., the target flow rate of hydraulic oil flowing into the rod-side oil chamber 8R of the arm cylinder 8. The smaller the value of the lever operation signal (larger the absolute value), the larger the value of the flow rate command.

[0088] Thereafter, the controller 30 causes the twelfth processing unit PU12 to output a value obtained by multiplying the flow rate command by the integral gain Ki to the thirteenth processing unit PU13.

[0089] Specifically, the controller 30 executes PC flow rate control of the second arm control valve 176B in the thirteenth processing unit PU13, and executes P1 pressure control of the first arm control valve 176A in the fourteenth processing unit PU14.

[0090] In the PC flow rate control of the second arm control valve 176B, the controller 30 moves the second arm control valve 176B so that the flow rate of hydraulic oil passing through the second PC port of the second arm control valve 176B becomes a target flow rate. More specifically, the controller 30 outputs a current command to the second arm solenoid valve 31B to adjust the pilot pressure acting on the right pilot port of the second arm control valve 176B, thereby adjusting the flow path area of ​​the second PC port of the second arm control valve 176B, thereby increasing or decreasing the flow rate of hydraulic oil passing through the second PC port of the second arm control valve 176B. Note that in the PC flow rate control of the second arm control valve 176B, the controller 30 calculates the flow rate of hydraulic oil passing through the second PC port of the second arm control valve 176B based on the difference between the pressure of hydraulic oil on the upstream side of the second PC port (pump discharge pressure PS detected by discharge pressure sensor 28) and the pressure of hydraulic oil on the downstream side of the second PC port (arm rod pressure P2 detected by arm rod pressure sensor S8R).

[0091] Furthermore, in the P1 pressure control of the first arm control valve 176A, the controller 30 moves the first arm control valve 176A so that the arm bottom pressure P1 becomes a predetermined pressure (zero in the illustrated example). More specifically, the controller 30 outputs a current command to the first arm solenoid valve 31A to adjust the pilot pressure acting on the left pilot port of the first arm control valve 176A and adjust the size of the flow path area of ​​the first CT port of the first arm control valve 176A, thereby increasing or decreasing the flow rate of hydraulic oil passing through the first CT port of the first arm control valve 176A, and thereby increasing or decreasing the arm bottom pressure P1. Typically, when the arm bottom pressure P1 exceeds the predetermined pressure, the controller 30 moves the first arm control valve 176A so that the flow path area of ​​the first CT port of the first arm control valve 176A becomes larger.

[0092] As a result, the controller 30 can open the arm while matching the flow rate Q2 of the hydraulic oil flowing through the first section CD21 of the second oil passage CD2 to the target flow rate and maintaining the arm bottom pressure P1 at a predetermined pressure, as shown in Figure 7.

[0093] Next, another control method of the controller 30 that controls the movement of the arm cylinder 8 will be described with reference to Fig. 9. Fig. 9 is a diagram for explaining another control method of the controller 30 that controls the movement of the arm cylinder 8, and corresponds to Fig. 5.

[0094] Specifically, the control method of Fig. 9 differs from the control method of Fig. 5 in that it has 15th processing unit PU15 to 17th processing unit PU17, but in other respects is the same as the control method of Fig. 5. Therefore, in the following, only the different parts will be described in detail, and a description of the common parts will be omitted.

[0095] When the operating device 26 (left operating lever) is operated in the arm closing direction, the controller 30 causes a fifteenth processing unit PU15 to derive a proportional gain Kp based on the lever operation signal output by the operating device 26 (left operating lever). In the illustrated example, the proportional gain Kp is set to be maximum when the lever operation amount of the operating device 26 (left operating lever) is a predetermined value TA. The predetermined value TA is a value between the minimum and maximum values. Specifically, the proportional gain Kp increases as the lever operation amount increases until the lever operation amount reaches the predetermined value TA. Conversely, once the lever operation amount exceeds the predetermined value TA, the proportional gain Kp decreases as the lever operation amount increases.

[0096] Thereafter, the controller 30 compensates the flow command using the proportional gain Kp. Specifically, the controller 30 multiplies the cylinder thrust value calculated by the third processing unit PU3 by the proportional gain Kp in the sixteenth processing unit PU16, and further multiplies this by ω / (s+ω) in the seventeenth processing unit PU17, and outputs the resulting value (compensation value) to the eighteenth processing unit PU18. Here, ω is the angular frequency, and s is the Laplace operator. Then, in the eighteenth processing unit PU18, the controller 30 subtracts the compensation value from the flow command and outputs the compensated flow command to the seventh processing unit PU7.

[0097] This control method has the effect of making it possible to make the change in the extension speed of the arm cylinder 8 (the amount of hydraulic oil flowing into the bottom-side oil chamber 8B) in response to changes in resistance (excavation reaction force) large in the intermediate operation range, making it easier for the operator to feel the excavation resistance. Also, this configuration has the effect of making it possible to make the change in the extension speed of the arm cylinder 8 (the amount of hydraulic oil flowing into the bottom-side oil chamber 8B) in response to changes in resistance (excavation reaction force) small during fine operation and maximum operation (full lever operation), making it possible to make small changes in the movement speed of the bucket 6 attached to the tip of the arm 5.

[0098] Next, with reference to Fig. 10, we will explain yet another control method of the controller 30 that controls the movement of the arm cylinder 8. Fig. 10 is a diagram for explaining yet another control method of the controller 30 that controls the movement of the arm cylinder 8, and corresponds to part of Fig. 5 (the part of the control method when performing high-power arm closing).

[0099] Specifically, the controller 30 derives a flow rate command in a 20th processing unit PU20 based on a lever operation signal output by the operating device 26 (left operation lever). In the illustrated example, the flow rate command is a flow rate command related to the target flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A, i.e., the target flow rate of hydraulic oil flowing into the bottom-side oil chamber 8B of the arm cylinder 8. The flow rate command has a larger value as the value of the lever operation signal increases.

[0100] Furthermore, the controller 30 derives a pressure command in a 23rd processing unit PU23 based on a lever operation signal output by the operating device 26 (left operation lever). The pressure command is a pressure command related to a target pressure of the pump discharge pressure PS, which is the pressure of the hydraulic oil discharged by the main pump 14, and is output to the regulator 13. The pressure command is a constant value when the value of the lever operation signal is equal to or less than a predetermined value TH, and when the value of the lever operation signal is above the predetermined value TH, the pressure command has a larger value as the value of the lever operation signal increases.

[0101] Thereafter, the controller 30, in a 21st processing unit PU21, executes PC flow rate control of the first arm control valve 176A so that the flow rate of hydraulic oil passing through the first PC port of the first arm control valve 176A becomes a target flow rate. Furthermore, in a 22nd processing unit PU22, the controller 30 executes P2 pressure control of the second arm control valve 176B so that the arm rod pressure P2 becomes a predetermined pressure (zero in the illustrated example). Furthermore, in a 24th processing unit PU24, the controller 30 executes pressure control of the main pump 14 so that the pump discharge pressure PS of the main pump 14 becomes a target pressure.

[0102] This configuration reduces the extension speed of the arm cylinder 8 (the amount of hydraulic oil flowing into the bottom-side oil chamber 8B) when the resistance (excavation reaction force) is large, thereby providing the effect of making it easier for the operator to feel the excavation resistance. With this configuration, when the arm bottom pressure P1 increases and approaches the pump discharge pressure PS, the difference between the pressure of the hydraulic oil on the upstream side of the first control valve V1 (first arm control valve 176A) (pump discharge pressure PS) and the pressure of the hydraulic oil on the downstream side of the first control valve V1 (first arm control valve 176A) (arm bottom pressure P1) approaches zero, and therefore the flow rate of the hydraulic oil passing through the first control valve V1 (first arm control valve 176A) also approaches zero, and the extension speed of the arm cylinder 8 decreases.

[0103] Next, with reference to Fig. 11, a description will be given of yet another control method of the controller 30 that controls the movement of the arm cylinder 8. Fig. 11 is a diagram for explaining yet another control method of the controller 30 that controls the movement of the arm cylinder 8, and corresponds to Fig. 5.

[0104] Specifically, the control method of Fig. 11 differs from the control method of Fig. 5 in that the control method for the first arm control valve 176A is the same when performing high-power arm closure and when performing high-speed arm closure, and in that the second arm control valve 176B is controlled by CP displacement control, but in other respects is the same as the control method of Fig. 5. Therefore, in the following, the different parts will be described in detail, and a description of the common parts will be omitted.

[0105] Specifically, the controller 30 determines in the sixth processing unit PU6A whether or not the cylinder thrust for extending the arm cylinder 8 exceeds a predetermined value. If the controller 30 determines that the cylinder thrust exceeds the predetermined value, it executes control details for performing high-power arm closing, and if it determines that the cylinder thrust does not exceed the predetermined value, it executes control details for performing high-speed arm closing.

[0106] In the control content when performing high-power arm closing, the seventh processing unit PU7 of the controller 30 executes PC flow control of the first arm control valve 176A, and the eighth processing unit PU8 executes P2 pressure control of the second arm control valve 176B. Note that the controller 30 does not execute the regeneration function when performing high-power arm closing.

[0107] On the other hand, in the control content for high-speed arm closing, the controller 30 executes PC flow control of the first arm control valve 176A in the seventh processing unit PU7, and executes CP displacement control of the second arm control valve 176B in the thirtieth processing unit PU30. "CP displacement control" means controlling the position of the second arm control valve 176B so that the flow path area of ​​the second PC port is maintained at a predetermined value. Note that the predetermined value may be a value stored in advance, or may be a value dynamically determined depending on the magnitude of the lever operation signal, etc.

[0108] All of the four control methods described above can control the arm rod pressure P2 to a predetermined value (for example, zero) when high-power arm closing is performed, and can control the arm bottom pressure to a predetermined value (for example, zero) when high-speed arm closing is performed. Therefore, all of the four control methods described above can minimize the pressure that acts to hinder the desired movement of the arm cylinder 8, and bring about the effect of realizing an energy-saving effect while realizing efficient movement of the arm cylinder 8.

[0109] Furthermore, all of the four control methods described above can control the flow rate (regenerated flow rate) of hydraulic oil that flows from the rod-side oil chamber 8R of the arm cylinder 8 to the junction JC when high-speed arm closing is performed. Therefore, all of the four control methods described above can cause the hydraulic oil that has flowed out from the rod-side oil chamber 8R of the arm cylinder 8 to flow into the bottom-side oil chamber 8B of the arm cylinder 8, bringing about the effect of achieving both a high extension speed of the arm cylinder 8 and an energy-saving effect.

[0110] As described above, the work machine 100 according to the embodiment of the present disclosure includes, as shown in Fig. 2, a lower traveling body 1, an upper rotating body 3 rotatably mounted on the lower traveling body 1, an attachment AT attached to the upper rotating body 3, and a hydraulic cylinder HC that moves the attachment AT. As shown in Fig. 6, the work machine 100 also includes a hydraulic pump (main pump 14) mounted on the upper rotating body 3, a first control valve V1 (first arm control valve 176A) provided in a first oil passage CD1 that connects the hydraulic pump (main pump 14) and one end side oil chamber (bottom side oil chamber 8B) of the hydraulic cylinder HC (arm cylinder 8), and a second control valve V2 (second arm control valve 176B) provided in a second oil passage CD2 that connects the hydraulic pump (main pump 14) and the other end side oil chamber (rod side oil chamber 8R) of the hydraulic cylinder HC (arm cylinder 8). As shown in FIG. 8, the work machine 100 is configured so that the hydraulic oil discharged from the other end side oil chamber (rod side oil chamber 8R) can be regenerated into the hydraulic cylinder HC (arm cylinder 8) through the second control valve V2 (second arm control valve 176B) and the first control valve V1 (first arm control valve 176A).

[0111] That is, in the work machine 100, the first control valve V1, which realizes the supply and discharge of hydraulic oil in the oil chamber on one end side of the hydraulic cylinder HC, and the second control valve V2, which realizes the supply and discharge of hydraulic oil in the oil chamber on the other end side of the hydraulic cylinder HC, are independent of each other. The work machine 100 is configured so that the first control valve V1 and the second control valve V2 operate appropriately to realize not only the extension function of the hydraulic cylinder HC and the contraction function of the hydraulic cylinder HC, but also the regeneration function, without being provided with regeneration valves that operate separately from the first control valve V1 and the second control valve V2.

[0112] This configuration does not include a regeneration valve, which has the advantage of enabling the regeneration function to be realized with a hydraulic circuit that is simpler than a hydraulic circuit that includes a regeneration valve. In other words, this configuration has the advantage of preventing the hydraulic circuit from becoming too complicated and reducing the manufacturing cost of the hydraulic circuit. Note that the "regeneration valve" is, for example, a valve that is provided in the oil passage connecting one end oil chamber and the other end oil chamber, separate from a control valve provided in the oil passage connecting the hydraulic pump and the hydraulic cylinder HC.

[0113] Furthermore, unlike a configuration in which the flow rate of hydraulic fluid flowing into the hydraulic cylinder HC (supply-side flow rate) and the flow rate of hydraulic fluid flowing out of the hydraulic cylinder HC (return-side flow rate) are controlled by the same spool valve (supply / discharge control spool valve), this configuration allows for independent control of the supply-side flow rate and the return-side flow rate or regeneration flow rate. Therefore, this configuration provides the advantage of being able to flexibly adjust the regeneration flow rate. This configuration also provides the advantage of being able to reduce pressure losses in each of the first control valve V1 and the second control valve V2 by flexibly combining flow rate control of the supply-side flow rate, pressure control of the supply-side flow rate, flow control of the return-side flow rate (regeneration flow rate), and pressure control of the return-side flow rate. This configuration also provides the advantage of being able to reduce the size of the control valve unit 17 because the first control valve V1 and the second control valve V2 have smaller dimensions than the supply / discharge control spool valves.

[0114] The hydraulic cylinder HC is a single-rod hydraulic cylinder, with one end oil chamber being a bottom oil chamber and the other end oil chamber being a rod oil chamber. In the illustrated example, the hydraulic cylinder HC is an arm cylinder 8, with one end oil chamber being a bottom oil chamber 8B of the arm cylinder 8 and the other end oil chamber being a rod oil chamber 8R of the arm cylinder 8.

[0115] This configuration has the effect of realizing an efficient movement of the arm cylinder 8 while achieving an energy saving effect by executing the regenerating function when the arm is being closed at high speed.

[0116] 8, when the arm cylinder 8 is moved while expanding the bottom-side oil chamber 8B and contracting the rod-side oil chamber 8R, that is, when the regeneration function is used, the flow path area of ​​the first PC port in the first arm control valve 176A, which connects the main pump 14 and the bottom-side oil chamber 8B, may be controlled so that the pressure of the hydraulic oil in the bottom-side oil chamber 8B (arm bottom pressure P1) becomes a predetermined pressure (for example, zero), and the flow path area of ​​the second PC port in the second arm control valve 176B, which connects the rod-side oil chamber 8R and the main pump 14, may be controlled so that the flow rate of the hydraulic oil passing through the second PC port becomes a predetermined flow rate. The predetermined flow rate is, for example, a target flow rate determined by the amount of operation of the left operating lever.

[0117] This configuration brings about the effect that high-speed arm closing can be realized while matching the flow rate Q2 of the hydraulic oil flowing out from the rod-side oil chamber 8R with the target flow rate and maintaining the arm bottom pressure P1 at a predetermined pressure (for example, zero). Also, by maintaining the arm bottom pressure P1 at a predetermined pressure (for example, zero), this configuration makes it possible to minimize the pressure that acts to hinder high-speed arm closing, and brings about the effect that energy saving can be achieved while realizing efficient movement of the arm cylinder 8.

[0118] In addition, the first arm control valve 176A may be configured to be in a first inflow state (state shown in Figure 6) that connects the main pump 14 to the bottom-side oil chamber 8B and blocks communication between the bottom-side oil chamber 8B and the hydraulic oil tank HT, a first outflow state (state shown in Figure 7) that blocks communication between the main pump 14 and the bottom-side oil chamber 8B and connects the bottom-side oil chamber 8B and the hydraulic oil tank HT, or a first neutral state (not shown) that blocks communication between the main pump 14 and the bottom-side oil chamber 8B and blocks communication between the bottom-side oil chamber 8B and the hydraulic oil tank HT. The second arm control valve 176B may be configured to be in a regeneration state (state shown in FIG. 8 ) in which the rod-side oil chamber 8R communicates with the main pump 14 (junction JC) and the rod-side oil chamber 8R is disconnected from the hydraulic oil tank HT; a second outflow state (state shown in FIG. 6 ) in which the main pump 14 and the rod-side oil chamber 8R are disconnected from the rod-side oil chamber 8R and the hydraulic oil tank HT is connected; or a second neutral state (not shown) in which the main pump 14 and the rod-side oil chamber 8R are disconnected from the rod-side oil chamber 8R and the hydraulic oil tank HT is connected. The second arm control valve 176B may be configured to communicate the rod-side oil chamber 8R with the junction JC and to communicate the rod-side oil chamber 8R with the hydraulic oil tank HT. In this case, the second arm control valve 176B may be configured to simultaneously adjust the flow path area of ​​the second PC port and the flow path area of ​​the second CT port. Typically, the second arm control valve 176B may be configured to be able to divide the hydraulic oil flowing out of the rod side oil chamber 8R into hydraulic oil flowing toward the confluence JC and hydraulic oil flowing toward the hydraulic oil tank HT.

[0119] This configuration provides the advantage that arm closing and arm opening can be achieved while performing the regeneration function as needed without utilizing a regeneration valve.

[0120] The work machine 100 may also be equipped with an operation sensor 29 that detects the operation content of the operating device 26 used to operate the hydraulic cylinder HC (arm cylinder 8), a first pressure sensor (arm bottom pressure sensor S8B) that detects the pressure of the hydraulic oil in the one end side oil chamber (bottom side oil chamber 8B), a second pressure sensor (arm rod pressure sensor S8R) that detects the pressure of the hydraulic oil in the other end side oil chamber (rod side oil chamber 8R), a third pressure sensor (discharge pressure sensor 28) that detects the discharge pressure of the hydraulic pump (main pump 14), and a control device (controller 30) that controls the movement of each of the first control valve V1 (first arm control valve 176A) and the second control valve V2 (second arm control valve 176B) based on the outputs of the operation sensor 29, the first pressure sensor (arm bottom pressure sensor S8B), the second pressure sensor (arm rod pressure sensor S8R), and the third pressure sensor (discharge pressure sensor 28). The operation device 26 and the operation sensor 29 may be an operation device 42 and an operation sensor 43 provided in the remote control room RC, respectively.

[0121] This configuration brings about the effect that the arm cylinder 8 can be efficiently operated in response to the lever operation of the operator in the cabin 10 by utilizing the outputs of the operation sensor 29, the first pressure sensor (arm bottom pressure sensor S8B), the second pressure sensor (arm rod pressure sensor S8R), the third pressure sensor (discharge pressure sensor 28), etc. Furthermore, this configuration brings about the effect that the arm cylinder 8 can be efficiently operated in response to the lever operation of the operator in the remote control room RC by utilizing the outputs of the operation sensor 43, the first pressure sensor (arm bottom pressure sensor S8B), the second pressure sensor (arm rod pressure sensor S8R), the third pressure sensor (discharge pressure sensor 28), etc.

[0122] Furthermore, as shown in FIG. 8, the work machine 100 may be configured so that the hydraulic oil discharged from the rod-side oil chamber 8R passes through the second arm control valve 176B and merges with the hydraulic oil passing through a portion of the first oil passage CD1 that connects the main pump 14 and the first arm control valve 176A (second portion CD12).

[0123] This configuration allows the hydraulic oil discharged from the rod side oil chamber 8R to merge at the confluence point JC located upstream of the first arm control valve 176A, thereby providing the advantage that the flow rate of hydraulic oil flowing into the bottom side oil chamber 8B can be accurately controlled by P1 pressure control of the first arm control valve 176A.

[0124] Furthermore, the remote operation system SYS according to the embodiment of the present disclosure includes the work machine 100 and a control device that controls the movement of the first control valve V1 (first arm control valve 176A) and the second control valve V2 (second arm control valve 176B). The control device may be the controller 30 or the remote controller 40.

[0125] This configuration brings about the effect that even when the work machine 100 is remotely operated, a work machine 100 that is not equipped with a regeneration valve can be made to perform the regeneration function.

[0126] In the above-described embodiment, the work machine 100 is configured so that hydraulic oil discharged from the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is smaller can be recycled to the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is larger. However, the work machine 100 may be configured so that hydraulic oil discharged from the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is recycled to the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is smaller. For example, in the above-described embodiment, the work machine 100 is configured so that hydraulic oil discharged from the rod-side oil chamber 8R of the arm cylinder 8 can be recycled to the bottom-side oil chamber 8B of the arm cylinder 8 via the second control valve V2 and the first control valve V1. However, the work machine 100 may be configured so that hydraulic oil discharged from the bottom-side oil chamber 8B of the arm cylinder 8 can be recycled to the rod-side oil chamber 8R of the arm cylinder 8 via the first control valve V1 and the second control valve V2. That is, work machine 100 may be configured to perform a regeneration function when the arms are open.

[0127] Furthermore, in the above-described embodiment, the work machine 100 is configured so that hydraulic oil discharged from the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is smaller can be recycled to the oil chamber on the side of the single-rod hydraulic cylinder where the pressure-receiving area of ​​the piston with which the hydraulic oil comes into contact is larger. However, the work machine 100 may also be configured so that hydraulic oil discharged from one oil chamber of a dual-rod hydraulic cylinder can be recycled to the other oil chamber of the dual-rod hydraulic cylinder.

[0128] Furthermore, although the above-described embodiment is applied to the control when the arm cylinder 8 is driven by one main pump 14, it can also be applied to the control when the arm cylinder 8 is driven by two main pumps 14.

[0129] Furthermore, the above-described embodiment is applied to the case where the arm cylinder 8 is driven, but it can also be applied to the case where the bucket cylinder 9 is driven in the same manner.

[0130] The preferred embodiments of the present disclosure have been described above. However, the invention according to the present disclosure is not limited to the above-described embodiments. Various modifications, substitutions, etc. may be applied to the above-described embodiments without departing from the scope of the invention according to the present disclosure. Furthermore, each of the features described with reference to the above-described embodiments may be combined as appropriate unless technically inconsistent. [Explanation of symbols]

[0131] 1···Undercarriage 1L···Left travel hydraulic motor 1R···Right travel hydraulic motor 2···Swing mechanism 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 unit 26···Operation device 28···Discharge pressure sensor 29···Operation sensor 30···Controller 31··Solenoid valve 31A···First arm solenoid valve 31B···Second arm solenoid valve 40···Remote controller 42···Operation device 43···Operation sensor 100···Work machine 171 to 176 Control valve A1 Microphone array A2 Speaker AT Attachment CD1 First oil passage CD2 Second oil passage CD3 Third oil passage CD4 Fourth oil passage CD11 First part CD12 Second part CD21 First part CD22 Second part D1 Display device D2 Display device DS Operator's seat HC Hydraulic cylinder HT Hydraulic oil tank JC Junction point NW Communication line OP Remote operator PD Positioning device PU1 First processing unit PU2 Second processing unit PU3 Third processing unit PU4 Fourth processing unit PU5 Fifth processing unit PU6, PU6A Sixth processing unit PU7 Seventh processing unit PU8···8th Processing Section PU9···9th Processing Section PU10···10th Processing Section PU11···11th Processing Section PU12···12th Processing Section PU13···13th Processing Section PU14···14th Processing Section PU15···15th Processing Section PU16···16th Processing Section PU17···17th Processing Section PU20···20th Processing Section PU21···21st Processing Section PU22···22nd Processing Section PU23···23rd Processing Section PU24···24th Processing Section PU30···30th Processing Section RC··Remote Control Room S1···Boom angle sensor S2···Arm angle sensor S3···Bucket angle sensor S4···Machine tilt sensor S5···Turning angular velocity sensor S6···Image capture device S6B···Rear camera S6F···Front cameraS6L···Left camera S6R···Right camera S7B···Boom bottom pressure sensor S7R···Boom rod pressure sensor S8B···Arm bottom pressure sensor S8R···Arm rod pressure sensor S9B···Bucket bottom pressure sensor S9R···Bucket rod pressure sensor SYS···Remote control system T1···Communication device T2···Communication device V1···First control valve V2···Second control valve

Claims

1. a lower running body; an upper rotating body rotatably mounted on the lower traveling body; an attachment attached to the upper rotating body; a hydraulic cylinder that moves the attachment; a hydraulic pump mounted on the upper rotating body; a first control valve provided in a first oil passage connecting the hydraulic pump and an oil chamber on one end side of the hydraulic cylinder; a second control valve provided in a second oil passage connecting the hydraulic pump and the other end side oil chamber of the hydraulic cylinder, The hydraulic oil discharged from the other end oil chamber can be regenerated into the hydraulic cylinder through the second control valve and the first control valve. Work machinery.

2. The hydraulic cylinder is a single-rod hydraulic cylinder, the one-end oil chamber is a bottom-side oil chamber of the hydraulic cylinder, The other end side oil chamber is a rod side oil chamber of the hydraulic cylinder.

2. The work machine according to claim 1.

3. When the hydraulic cylinder is moved while the bottom-side oil chamber is expanded and the rod-side oil chamber is contracted, a flow path area of ​​a first PC port in the first control valve connecting the hydraulic pump and the bottom-side oil chamber is controlled so that the pressure of the hydraulic oil in the bottom-side oil chamber becomes a predetermined pressure; a flow path area of ​​a second PC port in the second control valve connecting the rod side oil chamber and the hydraulic pump is controlled so that a flow rate of hydraulic oil passing through the second PC port becomes a predetermined flow rate; 3. The work machine according to claim 2.

4. the first control valve is configured to be in a first inflow state in which the hydraulic pump communicates with the bottom-side oil chamber and cuts off communication between the bottom-side oil chamber and the hydraulic oil tank, a first outflow state in which the hydraulic pump cuts off communication with the bottom-side oil chamber and communicates with the bottom-side oil chamber and the hydraulic oil tank, or a first neutral state in which the hydraulic pump cuts off communication with the bottom-side oil chamber and cuts off communication between the bottom-side oil chamber and the hydraulic oil tank, The second control valve is configured to be in a regeneration state in which the rod side oil chamber communicates with the hydraulic pump and the communication between the rod side oil chamber and the hydraulic oil tank is blocked, a second outflow state in which the communication between the hydraulic pump and the rod side oil chamber is blocked and the rod side oil chamber is connected to the hydraulic oil tank, or a second neutral state in which the communication between the hydraulic pump and the rod side oil chamber is blocked and the communication between the rod side oil chamber and the hydraulic oil tank is blocked.

3. The work machine according to claim 2.

5. an operation sensor that detects the operation of an operating device used to operate the hydraulic cylinder; a first pressure sensor for detecting the pressure of the hydraulic oil in the one-end oil chamber; a second pressure sensor for detecting the pressure of the hydraulic oil in the other end oil chamber; a third pressure sensor for detecting a discharge pressure of the hydraulic pump; a control device that controls the movement of each of the first control valve and the second control valve based on outputs of the operation sensor, the first pressure sensor, the second pressure sensor, and the third pressure sensor, 2. The work machine according to claim 1.

6. The hydraulic oil discharged from the other end side oil chamber passes through the second control valve and merges with the hydraulic oil passing through a portion of the first oil passage that connects the hydraulic pump and the first control valve.

2. The work machine according to claim 1.

7. a working machine including a lower traveling body, an upper rotating body rotatably mounted on the lower traveling body, an attachment attached to the upper rotating body, a hydraulic cylinder for moving the attachment, a hydraulic pump mounted on the upper rotating body, a first control valve provided in a first oil passage connecting the hydraulic pump and an oil chamber on one end of the hydraulic cylinder, and a second control valve provided in a second oil passage connecting the hydraulic pump and an oil chamber on the other end of the hydraulic cylinder, wherein hydraulic oil discharged from the oil chamber on the other end can be recycled to the hydraulic cylinder through the second control valve and the first control valve; a control device that controls the movement of each of the first control valve and the second control valve; Remote control systems for work machines.

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