Control system and control method for working machinery

Abstract

To suppress the decrease in efficiency of the hydraulic circuit. [Solution] The control system for the work machine includes a first circuit including a first group of actuators, a second circuit including a second group of actuators, a first pump that discharges hydraulic fluid into the first circuit, a second pump that discharges hydraulic fluid into the second circuit, a confluence separation valve that opens and closes a connecting passage connecting the first circuit and the second circuit, a first discharge pressure sensor that detects the discharge pressure of the hydraulic fluid discharged by the first pump, a second discharge pressure sensor that detects the discharge pressure of the hydraulic fluid discharged by the second pump, a power source that drives the first pump and the second pump, and a controller. The controller calculates a weighted average pressure of the discharge pressure of the first pump and the discharge pressure of the second pump, with the discharge flow rate of the hydraulic fluid discharged from the first pump and the discharge flow rate of the hydraulic fluid discharged from the second pump as weights, and calculates the upper limit flow rate of hydraulic fluid that can be supplied to the first circuit and the second circuit based on the upper limit horsepower that the power source can input to the first pump and the second pump and the weighted average pressure.

Description

[Technical Field]

[0001] This disclosure relates to a control system for a work machine and a control method for a work machine. [Background technology]

[0002] In the technical field related to working machinery, there is a known hydraulic circuit that includes a flow-combining / flow-dividing valve that switches between a combined state in which a first pump flow path and a second pump flow path are connected and a divided state in which the first pump flow path and the second pump flow path are separated, as disclosed in Patent Document 1. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2016 / 056675 [Overview of the project] [Problems that the invention aims to solve]

[0004] In Patent Document 1, the first hydraulic pump and the second hydraulic pump are driven by an engine. When the operating amount of the operating device for operating the hydraulic actuator is 100%, the maximum horsepower that the engine can input to the first hydraulic pump and the second hydraulic pump is sufficiently converted to the horsepower consumed by the hydraulic circuit, thereby suppressing a decrease in the efficiency of the hydraulic circuit.

[0005] This disclosure aims to suppress the decrease in efficiency of hydraulic circuits. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a control system for a working machine, including a first circuit including a first actuator group, a second circuit including a second actuator group, a first pump that discharges hydraulic oil to the first circuit, a second pump that discharges hydraulic oil to the second circuit, a confluence separation valve that opens and closes a connection passage connecting the first circuit and the second circuit, a first discharge pressure sensor that detects the discharge pressure of the hydraulic oil discharged by the first pump, a second discharge pressure sensor that detects the discharge pressure of the hydraulic oil discharged by the second pump, a power source that drives the first pump and the second pump, and a controller. The controller calculates a weighted average pressure of the discharge pressure of the first pump and the discharge pressure of the second pump, with the discharge flow rate of the hydraulic oil discharged from the first pump and the discharge flow rate of the hydraulic oil discharged from the second pump as weights, and calculates an upper limit flow rate of the hydraulic oil that can be supplied to the first circuit and the second circuit based on the upper limit horsepower that can be input to the first pump and the second pump by the power source and the weighted average pressure.

Effect of the Invention

[0007] According to the present disclosure, a decrease in the efficiency of the hydraulic circuit is suppressed.

Brief Description of the Drawings

[0008] [Figure 1] FIG. 1 is a side view showing a working machine according to the first embodiment. [Figure 2] FIG. 2 is a diagram schematically showing a control system of the working machine according to the first embodiment. [Figure 3] FIG. 3 is a hardware configuration diagram showing a controller according to the first embodiment. << [Figure 4] FIG. 4 is a functional block diagram showing a controller according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing a control method of the working machine according to the first embodiment. [Figure 6] FIG. 6 is a diagram for explaining the effect of the control method of the working machine according to the first embodiment. [Figure 7] FIG. 7 is a flowchart showing a control method of the working machine according to the second embodiment. [Figure 8]Figure 8 is a diagram illustrating the operation of the work machine according to the third embodiment. [Figure 9] Figure 9 is a functional block diagram showing the controller according to the third embodiment. [Modes for carrying out the invention]

[0009] [First Embodiment] The first embodiment will be described.

[0010] <Working machinery> Figure 1 is a side view showing a work machine 1 according to the first embodiment. The work machine 1 operates at a work site. Examples of work machines 1 include a hydraulic excavator, a wheel loader, and a bulldozer. In this embodiment, the work machine 1 is a hydraulic excavator. The work machine 1 comprises a traveling body 2, a slewing body 3, a work machine 4, a traveling motor 9, a slewing motor 5, a work machine cylinder 6, a controller 7, and an operating device 8.

[0011] The running body 2 supports the rotating body 3. The running body 2 has a pair of tracks 2A. The working machine 1 moves as the tracks 2A rotate.

[0012] The slewing body 3 is positioned above the traveling body 2. The slewing body 3 is rotatably (swivels) supported by the traveling body 2. The slewing body 3 has a cab 3A. The operator of the work machine 1 is seated in the cab 3A.

[0013] The work implement 4 is rotatably mounted on the slewing body 3. The work implement 4 includes a boom 4A, an arm 4B, and a bucket 4C. The boom 4A is rotatably connected to the front of the slewing body 3. The arm 4B is rotatably connected to the tip of the boom 4A. The bucket 4C is rotatably connected to the tip of the arm 4B.

[0014] The work machine 4 may include attachments other than the bucket 4C. Examples of attachments include a skeleton bucket, a concrete crusher, a gripper, and a hydraulic breaker.

[0015] The travel motor 9 moves the vehicle body 2. The travel motor 9 rotates the tracks 2A of the vehicle body 2. The vehicle body 2 includes the travel motor 9. The vehicle body 2 moves as the tracks 2A rotate. The travel motor 9 is a hydraulic motor driven by hydraulic fluid. The travel motor 9 is an example of an actuator driven by hydraulic fluid.

[0016] The slewing motor 5 rotates (swivels) the slewing body 3, which is supported by the traveling body 2. The slewing body 3 includes the slewing motor 5. The slewing motor 5 is a hydraulic motor driven by hydraulic fluid. The slewing motor 5 is an example of an actuator driven by hydraulic fluid.

[0017] The work implement cylinder 6 operates the work implement 4 attached to the slewing body 3. The work implement cylinder 6 is a hydraulic cylinder driven by hydraulic fluid. The work implement cylinder 6 is an example of an actuator driven by hydraulic fluid. The work implement cylinder 6 has a cylinder tube, a piston that is movable inside the cylinder tube, and a rod fixed to the piston. The piston divides the inside of the cylinder tube into a head chamber and a bottom chamber. The work implement cylinder 6 retracts as hydraulic fluid flows into the head chamber and out of the bottom chamber. The work implement cylinder 6 extends as hydraulic fluid flows into the bottom chamber and out of the head chamber. The work implement cylinder 6 includes a boom cylinder 6A, an arm cylinder 6B, and a bucket cylinder 6C.

[0018] The boom cylinder 6A operates the boom 4A. The base end of the cylinder tube of the boom cylinder 6A is connected to the slewing body 3, and the tip of the rod of the boom cylinder 6A is connected to the boom 4A. The operation of the boom 4A includes raising and lowering movements. When hydraulic fluid flows into the bottom chamber of the boom cylinder 6A and the boom cylinder 6A extends, the boom 4A is raised. When hydraulic fluid flows into the head chamber of the boom cylinder 6A and the boom cylinder 6A retracts, the boom 4A is lowered.

[0019] The arm cylinder 6B operates the arm 4B. The base end of the cylinder tube of the arm cylinder 6B is connected to the boom 4A, and the tip of the rod of the arm cylinder 6B is connected to the arm 4B. The operation of the arm 4B includes digging and dumping operations. When hydraulic fluid flows into the bottom chamber of the arm cylinder 6B and the arm cylinder 6B extends, the arm 4B performs the digging operation. When hydraulic fluid flows into the head chamber of the arm cylinder 6B and the arm cylinder 6B retracts, the arm 4B performs the dumping operation.

[0020] Bucket cylinder 6C operates bucket 4C. The base end of the cylinder tube of bucket cylinder 6C is connected to arm 4B, and the tip of the rod of bucket cylinder 6C is connected to bucket 4C via a link mechanism. The operation of bucket 4C includes digging and dumping operations. When hydraulic fluid flows into the bottom chamber of bucket cylinder 6C and bucket cylinder 6C extends, bucket 4C performs the digging operation. When hydraulic fluid flows into the head chamber of bucket cylinder 6C and bucket cylinder 6C retracts, bucket 4C performs the dumping operation.

[0021] The control device 8 is located in the cab 3A. The control device 8 is operated by an operator seated in the cab. The operator can operate the control device 8 while seated in the driver's seat located in the cab. The control device 8 is operated to operate the actuators of the work machine 1. The control device 8 is operated to operate the traveling body 2, the rotating body 3, and the work machine 4.

[0022] <Manipulation amount> The operating device 8 is operated to operate the actuators of the work machine 1. The actuators include a travel motor 9, a slewing motor 5, and a work machine cylinder 6. The operating device 8 includes a plurality of levers. When the operating device 8 is operated, an operating signal (electrical signal) is generated to operate the actuators of the work machine 1. The operating signal of the operating device 8 is transmitted to the controller 7. The operating signal of the operating device 8 includes the operating amount of the operating device 8. The operating amount indicates the value of the operating signal. The operating amount may be considered as the signal intensity of the operating signal. The operating amount may be considered as the operating angle (tilting angle) of the lever. The controller 7 obtains the operating amount from the operating device 8 and controls the actuators based on the operating amount of the operating device 8.

[0023] In the following description, the amount of force used to operate the work equipment cylinder 6 will be appropriately referred to as the work equipment operating amount. The amount of force used to operate the boom cylinder 6A will be appropriately referred to as the boom operating amount. The amount of force used to operate the arm cylinder 6B will be appropriately referred to as the arm operating amount. The amount of force used to operate the bucket cylinder 6C will be appropriately referred to as the bucket operating amount. The amount of force used to operate the slewing motor 5 will be appropriately referred to as the slewing operating amount. The amount of force used to operate the travel motor 9 will be appropriately referred to as the travel operating amount.

[0024] Two drive motors 9 are provided. As described above, the vehicle 2 has a pair of tracks 2A. One track 2A is located on the left side of the vehicle 2. The other track 2A is located on the right side of the vehicle 2. The drive motors 9 include a left drive motor 9L for rotating the left track 2A and a right drive motor 9R for rotating the right track 2A (see Figure 2). The drive operation amount is the amount of operation required to operate the left drive motor 9L and the right drive motor 9R, respectively.

[0025] In this embodiment, the operation signal (operated quantity) is generated by operating the operating device 8, but the operation signal may be generated by, for example, the controller 7. The operator may not operate the operating device 8, and the controller 7 may automatically generate the operation signal. The operation signal may be generated by a controller other than the controller 7. The other controller may be located outside the work machine 1. The operation signal may be transmitted from the controller located outside the work machine 1 to the controller 7 mounted on the work machine 1. The operating device 8 may be located outside the work machine 1. The work machine 1 may be remotely controlled by a remote control device located outside the work machine 1. When the work machine 1 is remotely controlled by a remote control device, a remote controller connected to the remote control device may generate the operation signal. The operation signal generated by the remote controller may be transmitted to the controller 7 mounted on the work machine 1.

[0026] The implement operation amount is the amount of operation for the implement cylinder 6. The boom operation amount is the amount of operation for the boom cylinder 6A. The arm operation amount is the amount of operation for the arm cylinder 6B. The bucket operation amount is the amount of operation for the bucket cylinder 6C. The slewing operation amount is the amount of operation for the slewing motor 5. The travel operation amount is the amount of operation for the travel motor 9. The travel operation amount is the amount of operation required to operate the left travel motor 9L and the right travel motor 9R, respectively.

[0027] In the following explanation, when the manipulated variable is zero, that is, when the control device for operating a certain actuator is not being operated, the manipulated variable will be considered to be 0%. When the manipulated variable is at its maximum, the manipulated variable will be considered to be 100%.

[0028] <Compound operation> The operating device 8 may be operated so that at least two of the multiple actuators of the work machine 1 operate simultaneously. For example, the operating device 8 may be operated so that the boom cylinder 6A and the arm cylinder 6B operate simultaneously. For example, the operating device 8 may be operated so that the boom cylinder 6A, the arm cylinder 6B, and the bucket cylinder 6C operate simultaneously. For example, the operating device 8 may be operated so that the boom cylinder 6A, the arm cylinder 6B, and the slewing motor 5 operate simultaneously. In the following description, operating the operating device 8 so that at least two actuators operate simultaneously will be appropriately referred to as a compound operation. Also, operating the operating device 8 so that the travel motor 9 and an actuator different from the travel motor 9 operate simultaneously will be appropriately referred to as a travel compound operation.

[0029] Furthermore, operating the control device 8 so that only one type of actuator among the multiple actuators of the work machine 1 operates is appropriately referred to as "single-unit operation." Single-unit operation includes work machine single-unit operation, in which the control device 8 is operated so that only the work machine cylinder 6 operates; slewing single-unit operation, in which the control device 8 is operated so that only the slewing motor 5 operates; and travel single-unit operation, in which the control device 8 is operated so that only the travel motor 9 operates. Work machine single-unit operation includes boom single-unit operation, in which the control device 8 is operated so that only the boom cylinder 6A operates; arm single-unit operation, in which the control device 8 is operated so that only the arm cylinder 6B operates; and bucket single-unit operation, in which the control device 8 is operated so that only the bucket cylinder 6C operates. As described above, the travel motor 9 includes a left travel motor 9L and a right travel motor 9R. Travel single-unit operation includes operation in which only one of the left travel motor 9L and the right travel motor 9R operates, and operation in which both the left travel motor 9L and the right travel motor 9R operate simultaneously, but the work machine cylinder 6 and the slewing motor 5 do not operate.

[0030] <Control System> Figure 2 is a schematic diagram showing the control system 13 of the work machine 1 according to the first embodiment. The control system 13 includes a hydraulic circuit (hydraulic system) that operates with hydraulic fluid. As shown in Figure 2, the control system 13 includes a controller 7, an operating device 8, a power source 14, a pump 15, a rotation speed sensor 24, a tank 16, a directional control valve 17, a meter-in pressure sensor 18, a meter-out pressure sensor 38, a pump passage 19, a suction passage 20, a discharge pressure sensor 11, a relief passage 22, a relief valve 23, a meter-in passage 21, a meter-out passage 31, a travel motor 9, a slewing motor 5, a work machine cylinder 6, and a confluence / separation valve 10.

[0031] Power source 14 is the power source for the work machine 1. A diesel engine is given as an example of power source 14. However, power source 14 may also be an electric motor. Power source 14 is connected to pump 15. Power source 14 drives pump 15.

[0032] Pump 15 is a hydraulic pump that discharges hydraulic fluid. Pump 15 discharges hydraulic fluid that is supplied to the actuators of the work machine 1. The actuators include a travel motor 9, a slewing motor 5, and a work machine cylinder 6. Pump 15 is a swashplate type variable displacement pump. The capacity [cc / rev] of pump 15 is changed by changing the angle of the swashplate of pump 15. Pump 15 draws up hydraulic fluid contained in tank 16 through the suction passage 20. Pump 15 discharges the hydraulic fluid drawn up from tank 16 into pump passage 19.

[0033] The flow rate of the hydraulic fluid discharged from pump 15 is proportional to the product of the capacity of pump 15 and the rotational speed of pump 15. Calculating, controlling, and setting the flow rate of the hydraulic fluid discharged from pump 15 includes calculating, controlling, and setting the capacity of pump 15 according to the rotational speed of pump 15.

[0034] Multiple pumps 15 are provided. In this embodiment, the pump 15 includes a first pump 15A and a second pump 15B. The first pump 15A and the second pump 15B are driven by a power source 14. The pump passage 19 includes a first pump passage 19A connected to the first pump 15A and a second pump passage 19B connected to the second pump 15B. The suction passage 20 includes a first suction passage 20A connected to the first pump 15A and a second suction passage 20B connected to the second pump 15B. The first pump 15A discharges hydraulic fluid into the first pump passage 19A. The second pump 15B discharges hydraulic fluid into the second pump passage 19B.

[0035] The rotation speed sensor 24 detects the rotation speed of the pump 15. The rotation speed sensor 24 detects the rotation speed of the first pump 15A and the rotation speed of the second pump 15B. The detection data from the rotation speed sensor 24 is transmitted to the controller 7.

[0036] The discharge pressure sensor 11 detects the discharge pressure of the hydraulic fluid discharged by the pump 15. The discharge pressure sensor 11 detects the discharge pressure of the pump 15 by detecting the pressure of the hydraulic fluid in the pump passage 19. The discharge pressure sensor 11 includes a first discharge pressure sensor 11A that detects the discharge pressure of the hydraulic fluid discharged by the first pump 15A, and a second discharge pressure sensor 11B that detects the discharge pressure of the hydraulic fluid discharged by the second pump 15B. The first discharge pressure sensor 11A detects the pressure of the hydraulic fluid in the first pump passage 19A. The second discharge pressure sensor 11B detects the pressure of the hydraulic fluid in the second pump passage 19B. The detection data from the discharge pressure sensor 11 is transmitted to the controller 7.

[0037] The relief channel 22 is connected to the pump channel 19. The relief channel 22 includes a first relief channel 22A connected to the first pump channel 19A and a second relief channel 22B connected to the second pump channel 19B.

[0038] The relief valve 23 is located in the relief passage 22. The relief valve 23 closes when the pressure in the pump passage 19 is less than or equal to a predetermined receipt pressure. The relief valve 23 opens when the pressure in the pump passage 19 reaches a predetermined cracking pressure. When the relief valve 23 opens, at least some of the hydraulic fluid in the pump passage 19 is discharged to the tank 16 via the relief passage 22. The relief valve 23 includes a first relief valve 23A located in the first relief passage 22A and a second relief valve 23B located in the second relief passage 22B. The first relief valve 23A opens when the first pump passage 19A reaches a predetermined cracking pressure. The second relief valve 23B opens when the second pump passage 19B reaches a predetermined cracking pressure.

[0039] Two drive motors 9 are provided. As described above, the vehicle 2 has a pair of tracks 2A. One track 2A is located on the left side of the vehicle 2. The other track 2A is located on the right side of the vehicle 2. The drive motors 9 include a left drive motor 9L for rotating the left track 2A and a right drive motor 9R for rotating the right track 2A.

[0040] The meter-in passage 21 connects the pump passage 19 to the actuator. Multiple meter-in passages 21 are provided to connect the pump passage 19 to each of the multiple actuators. In this embodiment, the meter-in passage 21 includes a first meter-in passage 21A connecting the first pump passage 19A to the boom cylinder 6A, a second meter-in passage 21B connecting the second pump passage 19B to the arm cylinder 6B, a third meter-in passage 21C connecting the first pump passage 19A to the bucket cylinder 6C, a fourth meter-in passage 21D connecting the second pump passage 19B to the slewing motor 5, a fifth meter-in passage 21L connecting the first pump passage 19A to the left travel motor 9L, and a sixth meter-in passage 21R connecting the second pump passage 19B to the right travel motor 9R.

[0041] The meter-out passage 31 connects the actuator and the tank 16. Multiple meter-out passages 31 are provided to connect each of the multiple actuators to the tank 16. In this embodiment, the meter-out passage 31 includes a first meter-out passage 31A connecting the boom cylinder 6A to the tank 16, a second meter-out passage 31B connecting the arm cylinder 6B to the tank 16, a third meter-out passage 31C connecting the bucket cylinder 6C to the tank 16, a fourth meter-out passage 31D connecting the slewing motor 5 to the tank 16, a fifth meter-out passage 31L connecting the left travel motor 9L to the tank 16, and a sixth meter-out passage 31R connecting the right travel motor 9R to the tank 16.

[0042] The directional control valve 17 controls the flow rate and direction of the hydraulic fluid supplied from the pump 15 to the actuators of the work machine 1. Multiple directional control valves 17 are provided to control the flow rate of hydraulic fluid supplied from the pump 15 to each of the multiple actuators. In this embodiment, the directional control valve 17 includes a first directional control valve 17A that controls the flow rate of hydraulic fluid supplied from the pump 15 to the boom cylinder 6A, a second directional control valve 17B that controls the flow rate of hydraulic fluid supplied from the pump 15 to the arm cylinder 6B, a third directional control valve 17C that controls the flow rate of hydraulic fluid supplied from the pump 15 to the bucket cylinder 6C, a fourth directional control valve 17D that controls the flow rate of hydraulic fluid supplied from the pump 15 to the slewing motor 5, a fifth directional control valve 17L that controls the flow rate of hydraulic fluid supplied from the pump 15 to the left travel motor 9L, and a sixth directional control valve 17R that controls the flow rate of hydraulic fluid supplied from the pump 15 to the right travel motor 9R. The first directional control valve 17A is located in the first meter-in passage 21A and the first meter-out passage 31A. The second directional control valve 17B is located in the second meter-in passage 21B and the second meter-out passage 31B. The third directional control valve 17C is located in the third meter-in passage 21C and the third meter-out passage 31C. The fourth directional control valve 17D is located in the fourth meter-in passage 21D and the fourth meter-out passage 31D. The fifth directional control valve 17L is located in the fifth meter-in passage 21L and the fifth meter-out passage 31L. The sixth directional control valve 17R is located in the sixth meter-in passage 21R and the sixth meter-out passage 31R.

[0043] The meter-in pressure sensor 18 detects the pressure of the hydraulic fluid in the meter-in passage 21 between the directional control valve 17 and the actuator. Multiple meter-in pressure sensors 18 are provided to detect the load pressure acting on each of the multiple actuators. In this embodiment, the meter-in pressure sensor 18 includes a first meter-in pressure sensor 18A for detecting the load pressure of the boom cylinder 6A, a second meter-in pressure sensor 18B for detecting the load pressure of the arm cylinder 6B, a third meter-in pressure sensor 18C for detecting the load pressure of the bucket cylinder 6C, a fourth meter-in pressure sensor 18D for detecting the load pressure of the slewing motor 5, a fifth meter-in pressure sensor 18L for detecting the load pressure of the left travel motor 9L, and a sixth meter-in pressure sensor 18R for detecting the load pressure of the right travel motor 9R. The first meter-in pressure sensor 18A detects the pressure in the first meter-in passage 21A between the first directional control valve 17A and the boom cylinder 6A. The second meter-in pressure sensor 18B detects the pressure in the second meter-in passage 21B between the second directional control valve 17B and the arm cylinder 6B. The third meter-in pressure sensor 18C detects the pressure in the third meter-in passage 21C between the third directional control valve 17C and the bucket cylinder 6C. The fourth meter-in pressure sensor 18D detects the pressure in the fourth meter-in passage 21D between the fourth directional control valve 17D and the swing motor 5. The fifth meter-in pressure sensor 18L detects the pressure in the fifth meter-in passage 21L between the fifth directional control valve 17L and the left travel motor 9L. The sixth meter-in pressure sensor 18R detects the pressure in the sixth meter-in passage 21R between the sixth directional control valve 17R and the right travel motor 9R. The detection data from the meter-in pressure sensors 18 is transmitted to the controller 7.

[0044] The meter-out pressure sensor 38 detects the pressure of the hydraulic fluid in the meter-out passage 31 between the actuator and the directional control valve 17. Multiple meter-out pressure sensors 38 are provided to detect the pressure of the hydraulic fluid in each of the multiple meter-out passages 31. In this embodiment, the meter-out pressure sensor 38 includes a first meter-out pressure sensor 38A that detects the pressure in the first meter-out passage 31A between the boom cylinder 6A and the first directional control valve 17A, a second meter-out pressure sensor 38B that detects the pressure in the second meter-out passage 31B between the arm cylinder 6B and the second directional control valve 17B, a third meter-out pressure sensor 38C that detects the pressure in the third meter-out passage 31C between the bucket cylinder 6C and the third directional control valve 17C, a fourth meter-out pressure sensor 38D that detects the pressure in the fourth meter-out passage 31D between the swing motor 5 and the fourth directional control valve 17D, a fifth meter-out pressure sensor 38L that detects the pressure in the fifth meter-out passage 31L between the left travel motor 9L and the fifth directional control valve 17L, and a sixth meter-out pressure sensor 38R that detects the pressure in the sixth meter-out passage 31R between the right travel motor 9R and the sixth directional control valve 17R.

[0045] The directional control valve 17 functions as a meter-in valve that controls the flow rate of hydraulic fluid supplied to the actuator from the meter-in passage 21.

[0046] The meter-in pressure sensor 18 detects the meter-in pressure, which indicates the pressure of the hydraulic fluid flowing into the actuator, when hydraulic fluid is flowing into the actuator from the meter-in flow path 21. The meter-in pressure sensor 18 also detects the load pressure acting on the actuator when hydraulic fluid is flowing into the actuator from the meter-in flow path 21.

[0047] The meter-out pressure sensor 38 detects the meter-out pressure, which indicates the pressure of the hydraulic fluid flowing out of the actuator, when hydraulic fluid is flowing out of the actuator into the meter-out passage 31.

[0048] In this embodiment, the hydraulic circuit of the control system 13 includes a first circuit 131 including a first group of actuators and a second circuit 132 including a second group of actuators. The first group of actuators includes a boom cylinder 6A, a bucket cylinder 6C, and a left travel motor 9L. The second group of actuators includes an arm cylinder 6B, a slewing motor 5, and a right travel motor 9R. The first circuit 131 includes a first pump passage 19A, a first relief passage 22A, a first relief valve 23A, a first directional control valve 17A, a third directional control valve 17C, a fifth directional control valve 17L, a first meter-in passage 21A, a third meter-in passage 21C, and a fifth meter-in passage 21L. The second circuit 132 includes a second pump passage 19B, a second relief passage 22B, a second relief valve 23B, a second directional control valve 17B, a fourth directional control valve 17D, a sixth directional control valve 17R, a second meter-in passage 21B, a fourth meter-in passage 21D, and a sixth meter-in passage 21R. The first pump 15A discharges hydraulic fluid into the first circuit 131. The second pump 15B discharges hydraulic fluid into the second circuit 132.

[0049] The confluence separation valve 10 opens and closes the connecting passage 130 that connects the first circuit 131 and the second circuit 132. The confluence separation valve 10 switches between a separated state, where the first circuit 131 and the second circuit 132 are separated, and a confluence state, where the first circuit 131 and the second circuit 132 are connected. When the confluence separation valve 10 closes, the system enters the separated state. When the confluence separation valve 10 opens, the system enters the confluence state. In the separated state, the hydraulic fluid discharged from the first pump 15A is not supplied to the second circuit 132, but is supplied to the first circuit 131. In the separated state, the hydraulic fluid discharged from the second pump 15B is not supplied to the first circuit 131, but is supplied to the second circuit 132. In the confluence state, the hydraulic fluid discharged from the first pump 15A is supplied to both the first circuit 131 and the second circuit 132. In the combined state, the hydraulic fluid discharged from the second pump 15B is supplied to the second circuit 132 and the first circuit 131, respectively.

[0050] The confluence / separation valve 10 is controlled to be in a separated state when the operating device 8 is operated, for example, so that the arm 4B performs an excavation operation. If the arm 4B does not perform an excavation operation, the confluence / separation valve 10 is controlled to be in a combined state. The confluence / separation valve 10 may also be controlled to be in a separated state if at least one of the discharge pressures of the first pump 15A and the second pump 15B exceeds a predetermined value. The confluence / separation valve 10 may also be controlled to be in a combined state if the discharge pressures of the first pump 15A and the second pump 15B are below a predetermined value.

[0051] <Controller> Figure 3 is a hardware configuration diagram showing a controller 7 according to the first embodiment. The controller 7 includes a computer 12. The computer 12 has a processor 12A such as a CPU (Central Processing Unit), a main memory 12B including non-volatile memory such as ROM (Read Only Memory) and volatile memory such as RAM (Random Access Memory), a storage 12C, an input / output interface 12D including input / output circuits, and a communication interface 12E including communication circuits. The functions of the controller 7 are stored in the storage 12C as a computer program 12F. The processor 12A reads the computer program 12F from the storage 12C, loads it into the main memory 12B, and executes processing according to the computer program 12F. The computer program 12F may be distributed to the computer 12 via a network.

[0052] Figure 4 is a functional block diagram showing the controller 7 according to the first embodiment. The controller 7 outputs control commands to control at least the directional control valve 17.

[0053] The controller 7 has multiple functional units. The functions of the controller 7's functional units are performed by the processor 12A. The controller 7's functional units include a weighted average pressure calculation unit 71, an upper limit flow rate calculation unit 72, a first pump target flow rate calculation unit 73, a second pump target flow rate calculation unit 74, a heavy excavation degree calculation unit 75, a heavy excavation first pump target flow rate calculation unit 76, a heavy excavation second pump target flow rate calculation unit 77, a first pump target flow rate interpolation unit 78, a second pump target flow rate interpolation unit 79, a first actuator group request flow rate calculation unit 81, a second actuator group request flow rate calculation unit 82, and a control unit 83.

[0054] The weighted average pressure calculation unit 71 calculates the weighted average pressure P1, which is the average of the discharge pressure P1 of the hydraulic fluid discharged by the first pump 15A and the discharge pressure P2 of the hydraulic fluid discharged by the second pump 15B. wa The weighted average pressure calculation unit 71 calculates the weighted average pressure P based on the detection data of the first discharge pressure sensor 11A and the detection data of the second discharge pressure sensor 11B. wa The weighted average pressure calculation unit 71 calculates the weighted average pressure P, using the discharge flow rate Q1 of the hydraulic fluid discharged from the first pump 15A and the discharge flow rate Q2 of the hydraulic fluid discharged from the second pump 15B as weights. wa Calculate.

[0055] The discharge flow rate Q1 of the first pump 15A may be the target flow rate of the hydraulic fluid discharged from the first pump 15A. The discharge flow rate Q2 of the second pump 15B may be the target flow rate of the hydraulic fluid discharged from the second pump 15B. The target flow rates may be determined based on the operating amount of the operating device 8.

[0056] The discharge flow rate Q1 of the first pump 15A may be the measured flow rate of the hydraulic fluid discharged from the first pump 15A. The discharge flow rate Q2 of the second pump 15B may be the measured flow rate of the hydraulic fluid discharged from the second pump 15B. The measured flow rate is the flow rate derived from the sensor detection data. The measured flow rate may be, for example, the actual discharge flow rate detected by a flow sensor, or it may be the flow rate calculated from the detected data of the rotational speed and capacity of the pump 15. Either the rotational speed or the capacity of the pump 15 may be replaced with a control target value.

[0057] Note that the weighted average pressure calculation unit 71 may calculate a weighted average pressure P with the capacities q1 of the first pump 15A and q2 of the second pump 15B as weights. wa It may be calculated.

[0058] The capacity q1 of the first pump 15A may be the target capacity of the first pump 15A. The capacity q2 of the second pump 15B may be the target capacity of the second pump 15B. The target capacity may be determined based on the operation amount of the operation device 8.

[0059] The capacity q1 of the first pump 15A may be the actual capacity of the first pump 15A. The capacity q2 of the second pump 15B may be the actual capacity of the second pump 15B. The actual capacity is the flow rate derived from the detection data of the sensor. The actual capacity may be, for example, the capacity calculated from the detection data of a swash plate sensor that detects the tilt angle of the swash plate of the pump 15.

[0060] The weighted average pressure calculation unit 71 calculates the weighted average pressure P based on the following formula (1). wa In the embodiment, the unit of the flow rate is [L / min], the unit of the horsepower is [kW], and the unit of the pressure is [MPa].

[0061]

Number

[0062] The upper limit flow rate calculation unit 72 calculates an upper limit flow rate Q of the hydraulic oil that the first pump 15A and the second pump 15B can supply to the first circuit 131 and the second circuit 132 based on the upper limit horsepower W that the power source 14 can input to the first pump 15A and the second pump 15B and the weighted average pressure P calculated by the weighted average pressure calculation unit 71. all and the weighted average pressure P calculated by the weighted average pressure calculation unit 71 wa The upper limit horsepower W all is known data derived from, for example, the specifications data of the power source 14. The upper limit flow rate Q all is all with the upper limit horsepower W all divided by the weighted average pressure P waIt is calculated by dividing by the upper limit flow rate Q. The upper limit flow rate calculation unit 72 calculates the upper limit flow rate Q based on the following equation (2). all Calculate.

[0063]

number

[0064] In this embodiment, the upper limit flow rate calculation unit 72 calculates the upper limit flow rate Q when the combined separation valve 10 is closed in the separated state. all Calculate.

[0065] The first pump target flow rate calculation unit 73 calculates the target flow rate of the hydraulic fluid discharged by the first pump 15A. The target flow rate of the first pump 15A is equal to the required flow rate of the hydraulic fluid required by the first actuator group. The required flow rate of the first actuator group is the flow rate of the hydraulic fluid required for the first actuator group to operate. The first pump target flow rate calculation unit 73 calculates the target flow rate of the first pump 15A based on the amount of operation of the operating device 8 for operating the first actuator group. The first pump target flow rate calculation unit 73 determines that the sum of the discharge flow rate Q1 of the hydraulic fluid discharged from the first pump 15A and the discharge flow rate Q2 of the hydraulic fluid discharged from the second pump 15B is equal to the upper limit flow rate Q calculated by the upper limit flow rate calculation unit 72. all The target flow rate of the first pump 15A is calculated so as not to exceed [Q]. That is, the first pump target flow rate calculation unit 73 calculates [Q]. all The target flow rate of the first pump 15A is calculated so that Q1 + Q2 is ≥ Q1.

[0066] The second pump target flow rate calculation unit 74 calculates the target flow rate of the hydraulic fluid discharged by the second pump 15B. The target flow rate of the second pump 15B is equal to the required flow rate of hydraulic fluid required by the second actuator group. The required flow rate of the second actuator group is the flow rate of hydraulic fluid necessary for the second actuator group to operate. The second pump target flow rate calculation unit 74 calculates the target flow rate of the second pump 15B based on the amount of operation of the operating device 8 for operating the second actuator group. The second pump target flow rate calculation unit 74 calculates the upper limit flow rate Q calculated by the upper limit flow rate calculation unit 72. allThe target flow rate of the second pump 15B is calculated so as not to exceed the limit.

[0067] The heavy digging degree calculation unit 75 calculates the heavy digging degree of the arm 4B of the work machine 4 based on the operating amount of the operating device 8 and the load pressure of the arm cylinder 6B. The load pressure of the arm cylinder 6B is detected by the second meter-in pressure sensor 18B. The heavy digging degree calculation unit 75 calculates the heavy digging degree of the arm 4B based on the operating amount of the operating device 8 and the detection data of the second meter-in pressure sensor 18B.

[0068] The degree of heavy digging is an indicator of how powerfully the work machine 4, including arm 4B, is attempting to excavate the target object. The degree of heavy digging is expressed as a value from 0% to 100%. When the load on arm 4B is small, the degree of heavy digging approaches 0%. When the load on arm 4B is large, the degree of heavy digging approaches 100%.

[0069] In this embodiment, the amount of manipulation used to calculate the degree of heavy digging includes the amount of arm manipulation used to dig with arm 4B. The degree of heavy digging is greater the larger the amount of arm manipulation. The amount of manipulation used to calculate the degree of heavy digging may also include the amount of arm manipulation used to dig with arm 4B and the amount of bucket manipulation used to dig with bucket 4C. The degree of heavy digging may be greater the larger the amount of arm manipulation and also greater the larger the amount of bucket manipulation.

[0070] The degree of heavy digging may increase as the driving force of the arm cylinder 6B increases while the arm 4B is performing the digging operation. The driving force of the arm cylinder 6B is expressed by the following formula.

[0071] [Driving force] = [Cylinder pressure on the meter-in side] × [Pressure-receiving area on the meter-in side] - [Cylinder pressure on the meter-out side] × [Pressure-receiving area on the meter-out side]

[0072] The cylinder pressure on the meter-in side corresponds to the meter-in pressure and is detected by the meter-in pressure sensor 18. The pressure on the meter-out side corresponds to the meter-out pressure and is detected by the meter-out pressure sensor 38.

[0073] The degree of heavy digging may increase as the drive pressure of the arm cylinder 6B or the meter-in pressure of the hydraulic fluid supplied to the arm cylinder 6B increases while the arm 4B is performing the digging operation. The drive pressure is expressed by the following formula using the driving force described above.

[0074] [Driving pressure] = [Driving force] / [Pressure-receiving area on the meter-in side]

[0075] The degree of heavy excavation may be reduced in the combined state when the confluence / separation valve 10 is open. In other words, the degree of heavy excavation in the combined state may be set to be less than the degree of heavy excavation in the separated state.

[0076] If a regeneration circuit is provided that allows the hydraulic fluid that has leaked out from the meter-out side of the arm cylinder 6B to flow into the meter-in side of the arm cylinder 6B, the degree of heavy excavation may be reduced in the regeneration state in which the hydraulic fluid that has leaked out from the meter-out side of the arm cylinder 6B flows into the meter-in side of the arm cylinder 6B.

[0077] The heavy excavation degree calculation unit 75 determines that the arm 4B is performing heavy excavation if it determines that the value of the heavy excavation degree is equal to or greater than a predetermined specified value. In the following description, the state of the work machine 4 when it is determined that the arm 4B is performing heavy excavation will be appropriately referred to as the "heavy excavation state".

[0078] The heavy excavation first pump target flow rate calculation unit 76 calculates the target flow rate of the hydraulic fluid discharged by the first pump 15A in the heavy excavation state. The heavy excavation first pump target flow rate calculation unit 76 uses the degree of heavy excavation calculated by the degree of heavy excavation calculation unit 75 and the upper limit horsepower W all Based on the discharge pressure of the first pump 15A, the target flow rate of the first pump 15A under heavy excavation conditions is calculated.

[0079] The heavy excavation second pump target flow rate calculation unit 77 calculates the target flow rate of the hydraulic fluid discharged by the second pump 15B in the heavy excavation state. The heavy excavation second pump target flow rate calculation unit 77 uses the degree of heavy excavation calculated by the degree of heavy excavation calculation unit 75 and the upper limit horsepower W all Based on the rotational speed of the second pump 15B, the target flow rate of the second pump 15B under heavy excavation conditions is calculated.

[0080] The first pump target flow rate interpolation unit 78 interpolates the target flow rate of the first pump 15A calculated in the first pump target flow rate calculation unit 73 with the target flow rate of the first pump 15A calculated in the heavy excavation first pump target flow rate calculation unit 76. The first pump target flow rate calculation unit 73 calculates the target flow rate of the first pump 15A when the work machine 4 is not in a heavy excavation state. The heavy excavation first pump target flow rate calculation unit 76 calculates the target flow rate of the first pump 15A when the work machine 4 is in a heavy excavation state. Based on the degree of heavy excavation, the target flow rate of the first pump 15A when it is not in a heavy excavation state and the target flow rate of the first pump 15A when it is in a heavy excavation state are interpolated.

[0081] The second pump target flow rate interpolation unit 79 interpolates the target flow rate of the second pump 15B calculated by the second pump target flow rate calculation unit 74 with the target flow rate of the second pump 15B calculated by the heavy excavation second pump target flow rate calculation unit 77. The second pump target flow rate calculation unit 74 calculates the target flow rate of the second pump 15B when the work machine 4 is not in a heavy excavation state. The heavy excavation second pump target flow rate calculation unit 77 calculates the target flow rate of the second pump 15B when the work machine 4 is in a heavy excavation state. Based on the degree of heavy excavation, the target flow rate of the second pump 15B when it is not in a heavy excavation state and the target flow rate of the second pump 15B when it is in a heavy excavation state are interpolated.

[0082] If the degree of heavy excavation is 100%, the heavy excavation first pump target flow rate calculation unit 76 determines the target horsepower, which is the horsepower that the first pump wants to output, to a predetermined horsepower value (for example, 60 kW). Based on the determined target horsepower of the first pump (for example, 60 kW) and the discharge pressure of the first pump 15A detected by the first discharge pressure sensor 11A, the heavy excavation first pump target flow rate calculation unit 76 calculates the target flow rate of the first pump 15A.

[0083] If the degree of heavy excavation is 100%, the heavy excavation second pump target flow rate calculation unit 77 determines the target horsepower, which is the horsepower that the second pump wants to output, to a predetermined horsepower value (for example, 40 kW). Based on the determined target horsepower of the second pump (for example, 40 kW) and the discharge pressure of the second pump 15B detected by the second discharge pressure sensor 11B, the heavy excavation second pump target flow rate calculation unit 77 calculates the target flow rate of the second pump 15B.

[0084] Furthermore, if the degree of heavy excavation is 100%, the heavy excavation first pump target flow rate calculation unit 76 calculates the target horsepower of the first pump 15A to the upper limit horsepower W. all The target flow rate calculation unit 76 for the heavy excavation first pump determines the target horsepower (for example, upper limit horsepower W) of the first pump 15A. all The target flow rate of the first pump 15A may be calculated based on 60% of the above and the discharge pressure of the first pump 15A detected by the first discharge pressure sensor 11A.

[0085] Furthermore, if the degree of heavy excavation is 100%, the heavy excavation second pump target flow rate calculation unit 77 sets the target horsepower of the second pump 15B to the upper limit horsepower W. all The target flow rate calculation unit 77 for the heavy excavation second pump determines the target horsepower (e.g., upper limit horsepower W) of the second pump 15B. all The target flow rate of the second pump 15B may be calculated based on 40% of the above and the discharge pressure of the second pump 15B detected by the second discharge pressure sensor 11B.

[0086] When the degree of heavy excavation is 0%, the target flow rates of the first pump 15A and the second pump 15B are determined based on the required flow rate of the actuator calculated based on the amount of operation of the operating device 8. That is, when the degree of heavy excavation is 0%, the target flow rate of the first pump 15A calculated by the first pump target flow rate interpolation unit 78 is determined to be the target flow rate calculated by the first pump target flow rate calculation unit 73. The target flow rate of the second pump 15B calculated by the second pump target flow rate interpolation unit 79 is determined to be the target flow rate calculated by the second pump target flow rate calculation unit 74.

[0087] When the degree of heavy excavation is 100%, the target flow rate of the first pump 15A calculated by the first pump target flow rate interpolation unit 78 is determined to be the target flow rate calculated by the heavy excavation first pump target flow rate calculation unit 76. The target flow rate of the second pump 15B calculated by the second pump target flow rate interpolation unit 79 is determined to be the target flow rate calculated by the heavy excavation second pump target flow rate calculation unit 77.

[0088] If the degree of heavy excavation is an intermediate value greater than 0% and less than 100%, the target flow rate of pump 15 (15A, 15B) when not in a heavy excavation state and the target flow rate of pump 15 (15A, 15B) when in a heavy excavation state are interpolated according to the value of the degree of heavy excavation. The interpolation method between the target flow rate of pump 15 (15A, 15B) when not in a heavy excavation state and the target flow rate of pump 15 (15A, 15B) when in a heavy excavation state may be linear interpolation or nonlinear interpolation. The smaller the degree of heavy excavation, the closer the target flow rate of pump 15 (15A, 15B) is calculated to be to the sum of the required flow rates of multiple actuators. The sum of the required flow rates of multiple actuators refers to the sum of the required flow rates of the first actuator group and the required flow rates of the second actuator group. In other words, the sum of the required flow rates of multiple actuators refers to the sum of the required flow rates of the actuators in the first actuator group that require hydraulic fluid, and the sum of the required flow rates of the actuators in the second actuator group that require hydraulic fluid.

[0089] The first actuator group request flow rate calculation unit 81 calculates the request flow rate for the first actuator group based on the amount of operation of the operating device 8 which is operated in combination to operate the actuators of the first actuator group, and the target flow rate of the first pump 15A which has been modified in the first pump target flow rate interpolation unit 78 based on the degree of heavy excavation, so that the request flow rate for the first actuator group matches the modified target flow rate of the first pump 15A. The first actuator group request flow rate calculation unit 81 calculates the request flow rate for the first actuator group so that the ratio of the request flow rates of the multiple actuators determined based on the amount of operation of the operating device 8 is maintained. For example, if the target flow rate of the first pump 15A after adjustment for the degree of heavy excavation is 140 [L / min], and the required flow rates of the boom cylinder 6A, bucket cylinder 6C, and left travel motor 9L, respectively, determined based on the operating amount of the operating device 8, are 100 [L / min], 100 [L / min], and 0 [L / min], the first actuator group required flow rate calculation unit 81 determines the required flow rates of the boom cylinder 6A, bucket cylinder 6C, and left travel motor 9L to be 70 [L / min], 70 [L / min], and 0 [L / min], respectively, so as to maintain the ratio of the required flow rates of the multiple actuators determined based on the operating amount of the operating device 8.

[0090] Similar to the first actuator group request flow rate calculation unit 81, the second actuator group request flow rate calculation unit 82 calculates the request flow rate for the second actuator group based on the amount of operation of the operating device 8 which is operated in combination to operate the actuators of the second actuator group, and the target flow rate of the second pump 15B which has been modified in the second pump target flow rate interpolation unit 79 based on the degree of heavy excavation, so that the request flow rate for the second actuator group matches the modified target flow rate of the second pump 15B. The second actuator group request flow rate calculation unit 82 calculates the request flow rate for the second actuator group so that the ratio of the request flow rates of the multiple actuators determined based on the amount of operation of the operating device 8 is maintained.

[0091] The first actuator group required flow rate calculation unit 81 calculates the opening area of ​​the directional control valves 17 (17A, 17C, 17L) that belong to the first circuit 131 and control the flow rate of hydraulic fluid supplied to the first actuator group, so that the required flow rate of hydraulic fluid for each of the multiple actuators of the first actuator group is supplied to the first actuator group.

[0092] The second actuator group required flow rate calculation unit 82 calculates the opening area of ​​the directional control valves 17 (17B, 17D, 17R) that belong to the second circuit 132 and control the flow rate of hydraulic fluid supplied to the second actuator group, so that the required flow rate of hydraulic fluid for each of the multiple actuators of the second actuator group is supplied to the second actuator group.

[0093] The control unit 83 outputs control commands to the directional control valves 17 (17A, 17C, 17L) belonging to the first circuit 131 so that the opening area of ​​the directional control valves 17 (17A, 17C, 17L) belonging to the first circuit 131 becomes the opening area calculated by the first actuator group requested flow rate calculation unit 81. The control unit 83 outputs control commands to the directional control valves 17 (17B, 17D, 17R) belonging to the second circuit 132 so that the opening area of ​​the directional control valves 17 (17B, 17D, 17R) belonging to the second circuit 132 becomes the opening area calculated by the second actuator group requested flow rate calculation unit 82.

[0094] As described above, when the degree of heavy excavation is small (0%), the controller 7 controls the first pump 15A so that the target flow rate of the hydraulic fluid discharged from the first pump 15A becomes the flow rate required by the first actuator group, and controls the second pump 15B so that the target flow rate of the hydraulic fluid discharged from the second pump 15B becomes the flow rate required by the second actuator group. As the degree of heavy excavation increases (approaching 100%), the controller 7 controls the first pump 15A and the second pump 15B so that the target flow rate of the second pump 15B changes along a predetermined equihorsepower line.

[0095] <Control Method> Figure 5 is a flowchart showing the control method for the work machine 1 according to the first embodiment. The weighted average pressure calculation unit 71 acquires detection data from the first discharge pressure sensor 11A and the second discharge pressure sensor 11B. Based on equation (1), the weighted average pressure P of the discharge pressure P1 of the first pump 15A and the discharge pressure P2 of the second pump 15B are weighted by the discharge flow rate Q1 of the hydraulic oil discharged from the first pump 15A and the discharge flow rate Q2 of the hydraulic oil discharged from the second pump 15B. wa Calculate (Step SA1).

[0096] The upper limit flow rate calculation unit 72 calculates the upper limit horsepower W all The weighted average pressure P calculated by the weighted average pressure calculation unit 71 wa Based on this, the upper limit flow rate Q of the hydraulic fluid that the first pump 15A and the second pump 15B can supply to the first circuit 131 and the second circuit 132 is all The upper limit flow rate calculation unit 72 calculates the upper limit flow rate Q based on equation (2). all Calculate (Step SA2).

[0097] The first pump target flow rate calculation unit 73 calculates the target flow rate of the first pump 15A when the work machine 4 is not in a heavy excavation state. The second pump target flow rate calculation unit 74 calculates the target flow rate of the second pump 15B when the work machine 4 is not in a heavy excavation state (step SA3).

[0098] The heavy digging degree calculation unit 75 calculates the heavy digging degree of the arm 4B of the work machine 4 based on the operating amount of the operating device 8 and the load pressure of the arm cylinder 6B (step SA4).

[0099] In the heavy excavation first pump target flow rate calculation unit 76, the target flow rate of the first pump 15A is calculated when the work machine 4 is in a heavy excavation state. In the heavy excavation second pump target flow rate calculation unit 77, the target flow rate of the second pump 15B is calculated when the work machine 4 is in a heavy excavation state.

[0100] The first pump target flow rate interpolation unit 78 interpolates the target flow rate of the first pump 15A when it is not in a heavy excavation state and the target flow rate of the first pump 15A when it is in a heavy excavation state, based on the degree of heavy excavation. The second pump target flow rate interpolation unit 79 interpolates the target flow rate of the second pump 15B when it is not in a heavy excavation state and the target flow rate of the second pump 15B when it is in a heavy excavation state, based on the degree of heavy excavation (step SA5).

[0101] The first actuator group request flow rate calculation unit 81 calculates the request flow rate for the first actuator group so that the request flow rate for the first actuator group matches the modified target flow rate for the first pump 15A, based on the amount of operation of the operating device 8 which is operated in combination to operate the actuators of the first actuator group and the target flow rate of the first pump 15A which is modified in the first pump target flow rate interpolation unit 78 based on the degree of heavy excavation. The first actuator group request flow rate calculation unit 81 calculates the request flow rate for the first actuator group so that the ratio of the request flow rates of the multiple actuators determined based on the amount of operation of the operating device 8 is maintained. Similar to the first actuator group request flow rate calculation unit 81, the second actuator group request flow rate calculation unit 82 calculates the request flow rate for the second actuator group so that the request flow rate for the second actuator group matches the modified target flow rate for the second pump 15B, based on the amount of operation of the operating device 8 which is operated in combination to operate the actuators of the second actuator group and the target flow rate of the second pump 15B which is modified in the second pump target flow rate interpolation unit 79 based on the degree of heavy excavation. The second actuator group request flow rate calculation unit 82 calculates the request flow rate for the second actuator group so as to maintain the ratio of the request flow rates of the multiple actuators determined based on the amount of operation of the operating device 8 (step SA6).

[0102] The control unit 83 outputs a control command to control the directional control valve 17 based on the required flow rates of each of the multiple actuators calculated in step SA6 (step SA7).

[0103] [effect] As described above, in this embodiment, the weighted average pressure P of the discharge pressure P1 of the first pump 15A and the discharge pressure P2 of the second pump is wa The maximum horsepower W is calculated. all and weighted average pressure P wa Based on this, the upper limit flow rate Q of the hydraulic fluid that can be supplied to the hydraulic circuit. all The following is calculated. According to the embodiment, the upper limit horsepower W all Since this is sufficiently converted into horsepower consumed by the hydraulic circuit, the decrease in the efficiency of the hydraulic circuit is suppressed.

[0104] For example, Q is the maximum horsepower of the first pump 15A. 1L In that case, the following equation (3) holds true. Upper limit horsepower Q of the second pump 15B 2L The same applies to this matter.

[0105]

number

[0106] Therefore, the upper limit flow rate Q all When controlled in this way, the horsepower consumed by the hydraulic circuit is as shown in equation (4) below, with an upper limit of horsepower W all This matches. Maximum horsepower W all Since the power consumption of the hydraulic circuit matches the power consumption of the hydraulic circuit, the decrease in the efficiency of the hydraulic circuit is suppressed.

[0107]

number

[0108] In this embodiment, the degree of heavy digging by the work machine 4 is calculated, and the first pump 15A and the second pump 15B are controlled so that the target flow rate of the second pump 15B, which discharges hydraulic fluid to the second circuit 132 to which the arm 4B belongs, changes along a predetermined equihorsepower line as the degree of heavy digging increases. When the arm 4B is in a heavy digging state, the flow rate of hydraulic fluid supplied to the arm cylinder 6B changes along a predetermined equihorsepower line, thereby suppressing a decrease in the operating speed of the digging arm 4B. Since the decrease in the operating speed of the arm 4B is suppressed, a decrease in work efficiency is suppressed.

[0109] Figure 6 is a diagram illustrating the effect of the control method for the work machine 1 according to the first embodiment. In the graph shown in Figure 6, the horizontal axis represents the discharge pressure of the hydraulic fluid of the second pump 15B when the discharge pressure of the hydraulic fluid of the first pump 15A is fixed. The vertical axis represents the target flow rate of the hydraulic fluid discharged from the pumps 15 (15A, 15B). Line L1n shows the relationship between the discharge pressure of the first pump 15A and the target flow rate when the degree of heavy excavation is 0%. Line L2n shows the relationship between the discharge pressure of the second pump 15B and the target flow rate when the degree of heavy excavation is 0%. Line L1w shows the relationship between the discharge pressure of the first pump 15A and the target flow rate when the degree of heavy excavation is 100%. Line L2w shows the relationship between the discharge pressure of the second pump 15B and the target flow rate when the degree of heavy excavation is 100%.

[0110] When the degree of heavy excavation is 0%, the ratio of the target flow rate of the first pump 15A to the target flow rate of the second pump 15B (target flow rate ratio) remains constant even if the pump discharge pressure changes. In this case, for example, when performing excavation work to level the ground using the work machine 4, the boom 4A and arm 4B can operate while maintaining their operating speed ratio even if the load pressure fluctuates.

[0111] When the degree of heavy excavation is 100%, and the target flow rate of the first pump 15A remains constant regardless of the discharge pressure of the second pump 15B, the target flow rate of the second pump 15B increases when the discharge pressure of the second pump 15B decreases. In other words, when the discharge pressure of the second pump 15B is low, hydraulic fluid is abundantly supplied to the arm cylinder 6B belonging to the second circuit 132. Since hydraulic fluid is abundantly supplied to the arm cylinder 6B, the decrease in the operating speed of the arm 4B is suppressed, and the decrease in work efficiency is suppressed.

[0112] As shown in the graph in Figure 6, when the degree of heavy excavation is 100%, the supply flow rate from the pump 15 for operating the boom 4A and bucket 4C is not affected by the load pressure of the arm cylinder 6B. Furthermore, since the operating speed of the arm 4B increases significantly when the load pressure of the arm cylinder 6B decreases, the effect of increasing the speed of the arm 4B when the excavation depth of the bucket 4C is reduced by raising the boom 4A and the load pressure is reduced is easily noticeable.

[0113] [Second Embodiment] A second embodiment will now be described. In the following description, components that are the same as or equivalent to those in the above-described embodiment will be denoted by the same reference numerals, and the descriptions of those components will be simplified or omitted.

[0114] As described in the first embodiment above, the weighted average pressure calculation unit 71 calculates the weighted average pressure P wa When calculating the weighted average pressure P when the discharge pressure sensor 11 is abnormal, detection data from the first discharge pressure sensor 11A and detection data from the second discharge pressure sensor 11B are acquired. wa The calculation method will be explained.

[0115] Figure 7 is a flowchart showing the control method for the work machine 1 according to the second embodiment. Below, the weighted average pressure P when the first discharge pressure sensor 11A is abnormal is shown. wa The calculation method for P will be explained below. If the first discharge pressure sensor 11A is abnormal, the weighted average pressure calculation unit 71 calculates the weighted average pressure P wa The detection data from the first discharge pressure sensor 11A cannot be used in the calculation.

[0116] The weighted average pressure calculation unit 71 detects an abnormality in the first discharge pressure sensor 11A (step SB1).

[0117] If the first discharge pressure sensor 11A is malfunctioning, the value of the detection data from the first discharge pressure sensor 11A may become excessively low or excessively high. The weighted average pressure calculation unit 71 can determine that the first discharge pressure sensor 11A is malfunctioning if the value of the detection data from the first discharge pressure sensor 11A is below a predetermined first threshold, or if the value of the detection data from the first discharge pressure sensor 11A is above a predetermined second threshold. The second threshold is a value greater than the first threshold.

[0118] Furthermore, the weighted average pressure calculation unit 71 may determine that the first discharge pressure sensor 11A is abnormal if the difference between the discharge pressure of the first pump 15A and the meter-in pressure of the hydraulic fluid supplied to the actuator operated by the operation device 8 among the first actuator group is greater than or equal to a predetermined threshold. The meter-in pressure of the hydraulic fluid supplied to the actuator is detected by the meter-in pressure sensor 18. If the difference between the value of the detection data from the meter-in pressure sensor 18 and the value of the detection data from the first discharge pressure sensor 11A is greater than or equal to a threshold, the weighted average pressure calculation unit 71 can determine that the first discharge pressure sensor 11A is abnormal.

[0119] If the first discharge pressure sensor 11A is malfunctioning, the control unit 83 outputs a control command to open the confluence separation valve 10 to enter a confluence state (step SB2). In other words, if the first discharge pressure sensor 11A is malfunctioning, the control unit 83 outputs a control command to open the confluence separation valve 10 so that the first circuit 131 and the second circuit 132 enter a confluence state.

[0120] When the fluids merge, the hydraulic fluid pressure in the first circuit 131 and the hydraulic fluid pressure in the second circuit 132 become substantially equal. The weighted average pressure calculation unit 71 calculates the weighted average pressure P based on the detection data of the second discharge pressure sensor 11B. waThe weighted average pressure calculation unit 71 calculates the weighted average pressure P2 of the second pump 15B as the discharge pressure P1 of the first pump 15A. wa The weighted average pressure calculation unit 71 replaces the "discharge pressure P1" in equation (1) with the "discharge pressure P2" detected by the second discharge pressure sensor 11B, and calculates the weighted average pressure P wa Calculate (Step SB3).

[0121] Furthermore, if both the first discharge pressure sensor 11A and the second discharge pressure sensor 11B are malfunctioning, the control unit 83 outputs a control command to open the confluence separation valve 10 to enter a confluence state. The weighted average pressure calculation unit 71 uses a predetermined alternative value P3 as the discharge pressure P1 of the first pump 15A and the discharge pressure P2 of the second pump 15B, and calculates the weighted average pressure P wa The weighted average pressure calculation unit 71 replaces "discharge pressure P1" and "discharge pressure P2" in equation (1) with "alternative value P3" to calculate the weighted average pressure P wa The value P3 is calculated. The alternative value P3 may be the cracking pressure of the relief valve 23 described above, or a value that approximates the cracking pressure.

[0122] [Third Embodiment] A third embodiment will now be described. In the following description, components that are the same as or equivalent to those in the embodiments described above will be denoted by the same reference numerals, and the descriptions of those components will be simplified or omitted.

[0123] Figure 8 is a diagram illustrating the operation of the work machine 1 according to the third embodiment. Figure 8 shows the steering state in which the travel body 2 of the work machine 1 is turning a curve. The travel body 2 has a left travel motor 9L and a right travel motor 9R. When the travel body 2 is turning a curve, a difference occurs between the load pressure of the left travel motor 9L and the load pressure of the right travel motor 9R. The left travel motor 9L belongs to the first circuit 131, and the right travel motor 9R belongs to the second circuit 132. For example, if the load pressure of the right travel motor 9R is lower than the load pressure of the left travel motor 9L, the upper limit torque of the second pump 15B decreases, and the upper limit torque of the first pump 15A increases. When the travel body 2 transitions from a steering state in which it is turning a curve to a straight-ahead state, if the recovery of the upper limit torque of the second pump 15B is delayed, it may become difficult for the travel body 2 to smoothly transition from the steering state to the straight-ahead state.

[0124] In this embodiment, the controller 7 distributes the total upper limit torque input from the power source 14 to the pumps 15 (15A, 15B) according to the ratio of the load torque of the first pump 15A to the load torque of the second pump 15B, so that the vehicle 2 can smoothly transition from a steering state to a straight-ahead state.

[0125] Figure 9 is a functional block diagram showing a controller 7 according to the third embodiment. The functional parts of the controller 7 include a total upper limit torque calculation unit 91, a target torque calculation unit 92, a target flow rate calculation unit 93, a total upper limit torque distribution unit 94, an individual upper limit torque calculation unit 95, a driving-only operation degree calculation unit 96, a first interpolation unit 97, a second interpolation unit 98, and a control unit 99.

[0126] The total upper limit torque calculation unit 91 calculates the upper limit horsepower W that the power source 14 can input to the first pump 15A and the second pump 15B. all Based on the rotational speed of pump 15, the power source 14 calculates the total upper limit torque that can be input to the first pump 15A and the second pump 15B. The total upper limit torque calculation unit 91 calculates the upper limit horsepower W all The total upper limit torque is calculated by dividing this by the rotational speed of pump 15.

[0127] The target flow rate calculation unit 93 calculates the target flow rate of the first circuit, which is the target flow rate of the hydraulic fluid supplied from the first pump 15A to the first circuit 131, based on the working equipment operating amount (boom operating amount, arm operating amount, and bucket operating amount), the slewing operating amount, and the travel operating amount. The target flow rate calculation unit 93 calculates the target flow rate of the second circuit, which is the target flow rate of the hydraulic fluid supplied from the second pump 15B to the second circuit 132, based on the working equipment operating amount and the travel operating amount.

[0128] The target torque calculation unit 92 calculates the first circuit target torque, which is the target torque for the first pump 15A, based on the amount of operation of the operating device 8 and the discharge pressure of the first pump 15A detected by the first discharge pressure sensor 11A. The target torque calculation unit 92 calculates the first circuit target torque, which is the target torque for the first pump 15A, based on the discharge pressure of the first pump 15A detected by the first discharge pressure sensor 11A and the first circuit target flow rate calculated by the target flow rate calculation unit 93.

[0129] The target torque calculation unit 92 calculates the second circuit target torque, which is the target torque for the second pump 15B, based on the amount of operation of the operating device 8 and the discharge pressure of the second pump 15B detected by the second discharge pressure sensor 11B. The target torque calculation unit 92 calculates the second circuit target torque, which is the target torque for the second pump 15B, based on the discharge pressure of the second pump 15B detected by the second discharge pressure sensor 11B and the second circuit target flow rate calculated by the target flow rate calculation unit 93.

[0130] The total upper limit torque distribution unit 94 distributes the total upper limit torque to the first pump 15A and the second pump 15B. The total upper limit torque distribution unit 94 distributes the total upper limit torque equally to the first pump 15A and the second pump 15B.

[0131] The individual upper limit torque calculation unit 95 distributes the total upper limit torque to the first pump 15A and the second pump 15B. The individual upper limit torque calculation unit 95 distributes the total upper limit torque to the first pump 15A and the second pump 15B based on the ratio of the first circuit target torque and the second circuit target torque calculated by the target torque calculation unit 92.

[0132] In the following explanation, the upper limit torque distributed to the first pump 15A will be appropriately referred to as the "first pump upper limit torque," and the upper limit torque distributed to the second pump 15B will be appropriately referred to as the "second pump upper limit torque."

[0133] The independent travel operation degree calculation unit 96 calculates the independent travel operation degree when the amount of operation required to simultaneously operate the work equipment cylinder 6 and the travel motor 9 (left travel motor 9L and right travel motor 9R) is obtained. The independent travel operation degree when the operating device 8 is operated so that the work equipment cylinder 6 and the travel motor 9 operate simultaneously refers to the magnitude of the work equipment operation amount relative to the travel operation amount. The smaller the work equipment operation amount is relative to the travel operation amount, the greater the independent travel operation degree. The larger the work equipment operation amount is relative to the travel operation amount, the smaller the independent travel operation degree. The independent travel operation degree is expressed as a value from 0% to 100%. In independent travel operation where the work equipment operation amount is zero and the operating device 8 is operated so that only the travel motor 9 operates, the independent travel operation degree is 100%. In independent work equipment operation (boom independent operation, arm independent operation, bucket independent operation) where the travel operation amount is zero and the operating device 8 is operated so that only the work equipment cylinder 6 operates, the independent travel operation degree is 0%. Furthermore, in combined travel operations where the amount of travel operation is maximum and the amount of work equipment operation is maximum, the degree of travel-only operation may be set to 0%.

[0134] The first interpolation unit 97 calculates the final first pump upper limit torque based on the first pump upper limit torque calculated by the total upper limit torque distribution unit 94, the first pump upper limit torque calculated by the individual upper limit torque calculation unit 95, and the degree of independent driving operation calculated by the independent driving operation degree calculation unit 96. The first interpolation unit 97 interpolates the first pump upper limit torque calculated by the total upper limit torque distribution unit 94 and the first pump upper limit torque calculated by the individual upper limit torque calculation unit 95 by the degree of independent driving operation.

[0135] When the degree of operation solely involving travel is 0%, that is, when it is a combined travel operation and the amount of work implement operation is relatively large, the first interpolation unit 97 calculates the first pump upper limit torque calculated by the individual upper limit torque calculation unit 95 as the final first pump upper limit torque. In other words, when the degree of operation solely involving travel is 0%, the first pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque becomes the final first pump upper limit torque.

[0136] When the degree of operation is solely based on travel, that is, when the amount of work implement operation is relatively small, even if it is solely travel operation or combined travel operation, the first interpolation unit 97 calculates the first pump upper limit torque calculated by the total upper limit torque distribution unit 94 as the final first pump upper limit torque. In other words, when the degree of operation is solely based on travel, the first pump upper limit torque, which is evenly distributed with the second pump upper limit torque, becomes the final first pump upper limit torque.

[0137] If the degree of independent operation is greater than 0% and less than 100%, the first pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque is interpolated with the first pump upper limit torque evenly distributed with the second pump upper limit torque, depending on the value of the independent operation degree. The interpolation method between the first pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque and the first pump upper limit torque evenly distributed with the second pump upper limit torque may be linear or nonlinear interpolation. The smaller the degree of independent operation, the closer the final first pump upper limit torque will be to the first pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque. The larger the degree of independent operation, the closer the final first pump upper limit torque will be to the first pump upper limit torque evenly distributed with the second pump upper limit torque.

[0138] The second interpolation unit 98 calculates the final second pump upper limit torque based on the second pump upper limit torque calculated by the total upper limit torque distribution unit 94, the second pump upper limit torque calculated by the individual upper limit torque calculation unit 95, and the degree of independent driving operation calculated by the independent driving operation degree calculation unit 96. The second interpolation unit 98 interpolates the second pump upper limit torque calculated by the total upper limit torque distribution unit 94 and the second pump upper limit torque calculated by the individual upper limit torque calculation unit 95 by the degree of independent driving operation.

[0139] When the degree of operation solely by driving is 0%, that is, when operation is solely by driving and the amount of work equipment operation is relatively large, the second interpolation unit 98 calculates the second pump upper limit torque calculated by the individual upper limit torque calculation unit 95 as the final second pump upper limit torque. In other words, when the degree of operation solely by driving is 0%, the second pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque becomes the final second pump upper limit torque.

[0140] When the degree of operation is 100% for travel alone, that is, when the amount of work implement operation is relatively small even in travel-only operation or travel-combined operation, the second interpolation unit 98 calculates the second pump upper limit torque calculated by the total upper limit torque distribution unit 94 as the final second pump upper limit torque. In other words, when the degree of operation is 100% for travel alone, the second pump upper limit torque, which is evenly distributed with the first pump upper limit torque, becomes the final second pump upper limit torque.

[0141] If the degree of independent operation is greater than 0% and less than 100%, the second pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque is interpolated with the second pump upper limit torque evenly distributed with the first pump upper limit torque, depending on the value of the independent operation degree. The interpolation method between the second pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque and the second pump upper limit torque evenly distributed with the first pump upper limit torque may be linear or nonlinear interpolation. The smaller the degree of independent operation, the closer the final second pump upper limit torque will be to the second pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque. The larger the degree of independent operation, the closer the final second pump upper limit torque will be to the second pump upper limit torque evenly distributed with the first pump upper limit torque.

[0142] The control unit 99 outputs a control command to control the first pump 15A based on the final first pump upper limit torque calculated by the first interpolation unit 97. The control unit 99 controls the first pump 15A so that the upper limit torque of the first pump 15A becomes the final first pump upper limit torque calculated by the first interpolation unit 97.

[0143] The control unit 99 outputs a control command to control the second pump 15B based on the final second pump upper limit torque calculated by the second interpolation unit 98. The control unit 99 controls the second pump 15B so that its upper limit torque becomes the final second pump upper limit torque calculated by the second interpolation unit 98.

[0144] As described above, in this embodiment, the controller 7 includes: a total upper limit torque calculation unit 91 that calculates the total upper limit torque that the power source 14 can input to the first pump 15A and the second pump 15B; a target torque calculation unit 92 that calculates a first circuit target torque, which is the target torque of the first pump 15A, and a second circuit target torque, which is the target torque of the second pump 15B, based on the amount of operation of the operating device 8, the discharge pressure P1 of the first pump 15A, and the discharge pressure P2 of the second pump 15B; an individual upper limit torque calculation unit 95 that distributes the total upper limit torque to the first pump 15A and the second pump 15B based on the ratio of the first circuit target torque and the second circuit target torque; and a control unit 99 that controls the first pump 15A and the second pump 15B based on the first pump upper limit torque, which is the upper limit torque distributed to the first pump 15A by the individual upper limit torque calculation unit 95, and the second pump upper limit torque, which is the upper limit torque distributed to the second pump 15B.

[0145] According to the embodiment, when the vehicle 2 transitions from a steering state where it is turning a curve to a straight-ahead state, the delay in the recovery of the upper limit torque of the pump 15 is suppressed, so that the vehicle 2 can smoothly transition from the steering state to the straight-ahead state. In particular, in driving-only operation, the total upper limit torque is evenly distributed between the first pump 15A and the second pump 15B, so that the vehicle 2 can smoothly transition from the steering state to the straight-ahead state.

[0146] In steering mode, for example, if the load pressure of the right drive motor 9R is lower than the load pressure of the left drive motor 9L, the upper limit torques distributed by the individual upper limit torque calculation unit 95 will be such that the upper limit torque of the second pump driving the right drive motor is large, and the upper limit torque driving the left drive motor is small. If control is implemented using these upper limit torques, the difference between the upper limit torque of the second pump and the load torque will be small in steering mode. Therefore, when returning to a straight-ahead state, the load torque of the second pump will be limited to its upper limit, and the swash plate angle cannot be increased quickly.

[0147] On the other hand, the upper limit torque distributed by the total upper limit torque distribution unit 94 is equal between the first pump and the second pump. When control is implemented using this upper limit torque, a sufficient margin can be provided in the difference between the upper limit torque of the second pump and the load torque in the steering state. Therefore, when returning to the straight-ahead state, the load torque of the second pump is not limited to the upper limit, and the swash plate angle can be increased quickly. Thus, a smooth transition from the steering state to the straight-ahead state is possible. [Explanation of Symbols]

[0148] 1...Work machine, 2...Traction unit, 2A...Tracks, 3...Slewing unit, 3A...Cab, 4...Work machine, 4A...Boom, 4B...Arm, 4C...Bucket, 5...Slewing motor, 6...Work machine cylinder, 6A...Boom cylinder, 6B...Arm cylinder, 6C...Bucket cylinder, 7...Controller, 8...Operating device, 9...Traction motor, 9L...Left transport motor, 9R...Right transport motor, 10...Merger / separator valve, 11...Discharge pressure sensor, 11A...First discharge pressure sensor, 11B...Second discharge pressure sensor, 12...Computer, 12A...Processor, 12B...Main memory, 12C...Storage, 12D...Input / Output Interface, 12E…Communication interface, 12F…Computer program, 13…Control system, 14…Power source, 15…Pump, 15A…First pump, 15B…Second pump, 16…Tank, 17…Directional control valve, 17A…First direction control valve, 17B…Second direction control valve, 17C…Third direction control valve, 17D…Fourth direction control valve, 17L…Fifth direction control valve, 17R…Sixth direction control valve, 18…Meter-in pressure sensor, 18A…First meter-in pressure sensor, 18B…Second meter-in pressure sensor, 18C…Third meter-in pressure sensor, 18D…Fourth meter-in pressure sensor, 18L…5th meter-in pressure sensor, 18R…6th meter-in pressure sensor, 19…Pump passage, 19A…1st pump passage, 19B…2nd pump passage, 20…Suction passage, 20A…1st suction passage, 20B…2nd suction passage, 21…Meter-in passage, 21A…1st meter-in passage, 21B…2nd meter-in passage, 21C…3rd meter-in passage, 21D…4th meter-in passage, 21L…5th meter-in passage, 21R…6th meter-in passage, 22…Relief passage, 22A…1st relief passage, 22B…2nd relief passage, 23…Relief valve, 23A…1st relief valve, 23 B...Second relief valve, 24...Rotation speed sensor, 31...Meter out passage, 31A...First meter out passage, 31B...Second meter out passage, 31C...Third meter out passage, 31D...Fourth meter out passage, 31L...Fifth meter out passage, 31R...Sixth meter out passage, 38...Meter out pressure sensor, 38A...First meter out pressure sensor, 38B...Second meter out pressure sensor, 38C...Third meter out pressure sensor, 38D...Fourth meter out pressure sensor, 38L...Fifth meter out pressure sensor, 38R...Sixth meter out pressure sensor, 71...Weighted average pressure calculation unit,72...Upper limit flow rate calculation unit, 73...First pump target flow rate calculation unit, 74...Second pump target flow rate calculation unit, 75...Heavy excavation degree calculation unit, 76...Heavy excavation first pump target flow rate calculation unit, 77...Heavy excavation second pump target flow rate calculation unit, 78...First pump target flow rate interpolation unit, 79...Second pump target flow rate interpolation unit, 81...First actuator group required flow rate calculation unit, 82...Second actuator group required flow rate calculation unit, 83...Control unit, 91...Total upper limit torque calculation unit, 92...Target torque calculation unit, 93...Target flow rate calculation unit, 94...Total upper limit torque distribution unit, 95...Individual upper limit torque calculation unit, 96...Single travel operation degree calculation unit, 97...First interpolation unit, 98...Second interpolation unit, 99...Control unit, 130...Connecting flow path, 131...First circuit, 132...Second circuit.

Claims

1. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A power source for driving the first pump and the second pump, Equipped with a controller, The aforementioned controller, The weighted average pressure of the discharge pressure of the first pump and the discharge pressure of the second pump is calculated, with the discharge flow rate of the hydraulic fluid discharged from the first pump and the discharge flow rate of the hydraulic fluid discharged from the second pump as weights. Based on the maximum horsepower that the power source can input to the first pump and the second pump and the weighted average pressure, the maximum flow rate of the hydraulic fluid that can be supplied to the first circuit and the second circuit is calculated. Control system for industrial machinery.

2. The discharge flow rate of the first pump is the target flow rate of the hydraulic fluid discharged from the first pump. The discharge flow rate of the second pump is the target flow rate of the hydraulic fluid discharged from the second pump. A control system for a work machine according to claim 1.

3. The discharge flow rate of the first pump is the measured flow rate of the hydraulic fluid discharged from the first pump. The discharge flow rate of the second pump is the measured flow rate of the hydraulic fluid discharged from the second pump. A control system for a work machine according to claim 1.

4. The aforementioned controller, In the separated state when the aforementioned merging and separating valve is closed, the upper limit flow rate is calculated. A control system for a work machine according to claim 1.

5. The aforementioned controller, If the first discharge pressure sensor is abnormal, a control command is output to open the confluence separation valve and enter a confluence state. The weighted average pressure is calculated by taking the discharge pressure of the second pump as the discharge pressure of the first pump. A control system for a work machine according to claim 1.

6. The aforementioned controller, If the value of the detection data from the first discharge pressure sensor is below a first threshold or above a second threshold, it is determined that the first discharge pressure sensor is abnormal. A control system for a work machine according to claim 5.

7. The aforementioned controller, If the difference between the discharge pressure of the first pump and the meter-in pressure of the hydraulic fluid supplied to the first actuator group in the first circuit is greater than or equal to a threshold, the first discharge pressure sensor is determined to be abnormal. A control system for a work machine according to claim 5.

8. The aforementioned controller, If the first discharge pressure sensor and the second discharge pressure sensor are abnormal, a control command is output to open the confluence separation valve and enter a confluence state. The weighted average pressure is calculated using predetermined alternative values ​​as the discharge pressure of the first pump and the discharge pressure of the second pump. A control system for a work machine according to claim 1.

9. The first pump discharges hydraulic fluid into the first pump passage included in the first circuit. The second pump discharges hydraulic fluid into the second pump passage included in the second circuit. A first relief valve is provided in a first relief passage connected to the first pump passage, and opens when the first pump passage reaches a predetermined cracking pressure, The system includes a second relief valve located in a second relief passage connected to the second pump passage, which opens when the second pump passage reaches a predetermined cracking pressure, The aforementioned alternative value is the cracking pressure or a value that approximates the cracking pressure. A control system for a work machine according to claim 8.

10. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A meter-in pressure sensor for detecting the pressure of the hydraulic fluid flowing into the actuators of the first actuator group and the second actuator group, A power source for driving the first pump and the second pump, Equipped with a controller, At least one of the second group of actuators is an arm cylinder that operates the arm of the work machine, The controller is The amount of operation required to operate the first group of actuators and the second group of actuators is obtained. Based on the aforementioned operating amount and the load pressure of the arm cylinder detected by the meter-in pressure sensor, the degree of heavy excavation of the work machine is calculated. When the degree of heavy excavation is small, the first pump is controlled so that the target flow rate of the hydraulic fluid discharged from the first pump becomes the required flow rate for the operation of the first actuator group, and the second pump is controlled so that the target flow rate of the hydraulic fluid discharged from the second pump becomes the required flow rate for the operation of the second actuator group. As the degree of heavy excavation increases, control at least one of the first pump and the second pump so that the target flow rate of the second pump changes along a predetermined equihorsepower line. Control system for industrial machinery.

11. The aforementioned operating amount includes the arm operating amount for performing the excavation operation of the arm, The degree of heavy excavation increases as the amount of arm operation increases. A control system for a work machine according to claim 10.

12. The aforementioned operating amount includes an arm operating amount for performing an excavation operation on the arm and a bucket operating amount for performing an excavation operation on the bucket of the work machine. The degree of heavy excavation increases with increasing arm movement, or increases with increasing bucket movement. A control system for a work machine according to claim 10.

13. The system includes a meter-out pressure sensor that detects the pressure of the hydraulic fluid flowing out of the actuator, The aforementioned controller, Based on the detection data from the meter-in pressure sensor and the detection data from the meter-out pressure sensor, the driving force of the arm cylinder is calculated. The degree of heavy digging increases as the driving force of the arm cylinder increases while the arm is performing the digging operation. A control system for a work machine according to claim 10.

14. The system includes a meter-out pressure sensor that detects the pressure of the hydraulic fluid flowing out of the actuator, The aforementioned controller, Based on the detection data from the meter-in pressure sensor and the detection data from the meter-out pressure sensor, the driving force of the arm cylinder is calculated. The degree of heavy digging increases as the drive pressure of the arm cylinder or the meter-in pressure of the hydraulic fluid supplied to the arm cylinder increases while the arm is performing the digging operation. A control system for a work machine according to claim 10.

15. The degree of heavy excavation decreases when the confluence valve is open in the confluence state. A control system for a work machine according to claim 10.

16. The degree of heavy excavation decreases in the regeneration state when the hydraulic fluid that has flowed out of the arm cylinder flows back into the arm cylinder. A control system for a work machine according to claim 10.

17. If the degree of heavy excavation is 100%, The aforementioned controller, The target horsepower, which is the horsepower that the second pump is to output, is determined to a predetermined horsepower value. Based on the target horsepower and discharge pressure of the second pump, the target flow rate of the second pump is calculated. A control system for a work machine according to claim 10.

18. If the degree of heavy excavation is 100%, The aforementioned controller, The target horsepower of the second pump is determined to be a predetermined ratio of the maximum horsepower that the power source can input to the first pump and the second pump. Based on the target horsepower and discharge pressure of the second pump, the target flow rate of the second pump is calculated. A control system for a work machine according to claim 10.

19. If the degree of heavy excavation is 100%, The aforementioned controller, The target horsepower of the second pump is determined to be a predetermined ratio of the maximum horsepower that the power source can input to the first pump and the second pump. Based on the target horsepower and discharge pressure of the second pump, the target flow rate of the second pump is calculated. If the degree of heavy excavation is 0%, The controller calculates the target flow rate of the first pump and the target flow rate of the second pump such that the target flow rate of the first pump becomes the required flow rate for the operation of the first actuator group, and the target flow rate of the second pump becomes the required flow rate for the operation of the second actuator group. If the aforementioned degree of heavy excavation is an intermediate value greater than 0% and less than 100%, The aforementioned controller, The smaller the degree of heavy excavation, the closer the target flow rate of the first pump and the target flow rate of the second pump are to the sum of the required flow rate of the first actuator group and the required flow rate of the second actuator group. A control system for a work machine according to claim 10.

20. The aforementioned controller, Based on the amount of operation required to simultaneously operate multiple actuators of the first actuator group and the target flow rate of the first pump modified based on the degree of heavy excavation, the required flow rate for each of the multiple actuators to operate is calculated such that the required flow rate of the first actuator group matches the modified target flow rate of the first pump, and the ratio of the required flow rates of the multiple actuators determined based on the amount of operation is maintained. A control system for a work machine according to claim 10.

21. The aforementioned controller, Based on the calculated required flow rates of each of the multiple actuators, the meter-in valve that controls the flow rate of the hydraulic fluid belonging to the first circuit and supplied to the first group of actuators is controlled. A control system for a work machine according to claim 20.

22. The aforementioned controller, Based on the amount of operation to simultaneously operate multiple actuators of the second actuator group and the target flow rate of the second pump modified based on the degree of heavy excavation, the required flow rate of each of the multiple actuators is calculated such that the required flow rate of the second actuator group matches the modified target flow rate of the second pump, and the ratio of the required flow rates of the multiple actuators determined based on the amount of operation is maintained. A control system for a work machine according to claim 10.

23. The aforementioned controller, Based on the calculated required flow rates of each of the multiple actuators, a meter-in valve that controls the flow rate of hydraulic fluid belonging to the second circuit and supplied to the second group of actuators is controlled. A control system for a work machine according to claim 22.

24. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A power source for driving the first pump and the second pump, Equipped with a controller, The aforementioned controller, The power source calculates the total upper limit torque that can be input to the first pump and the second pump, The amount of operation required to operate the first group of actuators and the second group of actuators is obtained. Based on the total upper limit torque, the operating amount, the discharge pressure of the first pump, and the discharge pressure of the second pump, the first pump and the second pump are controlled. Control system for industrial machinery.

25. The aforementioned controller, Based on the manipulated amount, the discharge pressure of the first pump, and the discharge pressure of the second pump, the first circuit target torque, which is the target torque of the first pump, and the second circuit target torque, which is the target torque of the second pump, are calculated. Based on the ratio of the target torque of the first circuit to the target torque of the second circuit, the total upper limit torque is distributed to the first pump and the second pump. Based on the first pump upper limit torque, which is the upper limit torque distributed to the first pump, and the second pump upper limit torque, which is the upper limit torque distributed to the second pump, the first pump and the second pump are controlled. A control system for a work machine according to claim 24.

26. The aforementioned work machine comprises a traveling body, a slewing body rotatably supported on the traveling body, and a work machine rotatably attached to the slewing body. The first actuator group and the second actuator group include a travel motor for moving the traveling body, a slewing motor for rotating the slewing body, and a work machine cylinder for operating the work machine, The aforementioned controller, The aforementioned total upper limit torque is distributed equally between the first pump and the second pump. The degree of independent travel operation is calculated based on the amount of operation required to simultaneously operate the work machine cylinder or the swing motor and the travel motor. The smaller the amount of operation required to operate the work implement compared to the amount of operation required to operate the travel motor, the greater the degree of operation required for travel alone. The aforementioned controller, In accordance with the value of the degree of independent operation of the drive, the first pump upper limit torque calculated based on the ratio of the first circuit target torque to the second circuit target torque is interpolated with the second pump upper limit torque and the first pump upper limit torque which is evenly distributed to calculate the final first pump upper limit torque. Based on the value of the degree of independent operation of the vehicle, the second pump upper limit torque, calculated based on the ratio of the first circuit target torque to the second circuit target torque, is interpolated with the second pump upper limit torque, which is evenly distributed with the first pump upper limit torque, to calculate the final second pump upper limit torque. Based on the final first pump upper limit torque and the final second pump upper limit torque, the first pump and the second pump are controlled. A control system for a work machine according to claim 25.

27. The smaller the degree of independent operation during driving, the closer the final upper limit torque of the first pump will be to the upper limit torque of the first pump calculated based on the ratio of the target torque of the first circuit to the target torque of the second circuit, and the closer the final upper limit torque of the second pump will be to the upper limit torque of the second pump calculated based on the ratio of the target torque of the first circuit to the target torque of the second circuit. The greater the degree of independent operation during driving, the closer the final upper limit torque of the first pump will be to the upper limit torque of the first pump when evenly distributed with the upper limit torque of the second pump, and the closer the final upper limit torque of the second pump will be to the upper limit torque of the second pump when evenly distributed with the upper limit torque of the first pump. A control system for a work machine according to claim 26.

28. In the case of a drive-only operation with a high degree of drive-only operation, the first pump upper limit torque, which is evenly distributed with the second pump upper limit torque, becomes the final first pump upper limit torque, and the second pump upper limit torque, which is evenly distributed with the first pump upper limit torque, becomes the final second pump upper limit torque. A control system for a work machine according to claim 26.

29. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A power source for driving the first pump and the second pump, A control method for a work machine comprising a controller, The aforementioned controller, The weighted average pressure of the discharge pressure of the first pump and the discharge pressure of the second pump is calculated, with the discharge flow rate of the hydraulic fluid discharged from the first pump and the discharge flow rate of the hydraulic fluid discharged from the second pump as weights. Based on the maximum horsepower that the power source can input to the first pump and the second pump and the weighted average pressure, the maximum flow rate of the hydraulic fluid that can be supplied to the first circuit and the second circuit is calculated. A method for controlling industrial machinery.

30. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A meter-in pressure sensor for detecting the pressure of the hydraulic fluid flowing into the actuators of the first actuator group and the second actuator group, A power source for driving the first pump and the second pump, A control method for a work machine comprising a controller, At least one of the second group of actuators is an arm cylinder that operates the arm of the work machine, The aforementioned controller, The amount of operation required to operate the first group of actuators and the second group of actuators is obtained. Based on the aforementioned manipulation amount and the load pressure of the arm cylinder detected by the meter-in pressure sensor, the degree of heavy excavation of the work machine is calculated. When the degree of heavy excavation is small, the first pump is controlled so that the target flow rate of the hydraulic fluid discharged from the first pump is the flow rate required by the first actuator group, and the second pump is controlled so that the target flow rate of the hydraulic fluid discharged from the second pump is the flow rate required by the second actuator group. As the degree of heavy excavation increases, the first pump and the second pump are controlled so that the target flow rate of the second pump changes along a predetermined equihorsepower line. A method for controlling industrial machinery.

31. A first circuit including a first group of actuators, A second circuit including a second group of actuators, The first circuit includes a first pump that discharges hydraulic fluid, The second circuit includes a second pump that discharges hydraulic fluid, A merging and separating valve that opens and closes a connecting channel connecting the first circuit and the second circuit, A first discharge pressure sensor for detecting the discharge pressure of the hydraulic fluid discharged by the first pump, A second discharge pressure sensor detects the discharge pressure of the hydraulic fluid discharged by the second pump, A power source for driving the first pump and the second pump, A control method for a work machine comprising a controller, The aforementioned controller, The power source calculates the total upper limit torque that can be input to the first pump and the second pump, The amount of operation required to operate the first group of actuators and the second group of actuators is obtained. Based on the total upper limit torque, the operating amount, the discharge pressure of the first pump, and the discharge pressure of the second pump, the first pump and the second pump are controlled. A method for controlling industrial machinery.

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