System and method for controlling a work machine

Abstract

To suppress deterioration of working efficiency.SOLUTION: A control system of a work machine includes: a plurality of hydraulic pumps for discharging hydraulic oil; a hydraulic cylinder for operating a work machine element; a plurality of flow rate control valves connected to each of the plurality of hydraulic pumps and adjusting a flow rate of the hydraulic oil to be supplied to the hydraulic cylinder; a plurality of supply flow passages connected to each of the plurality of flow rate control valves; a meter-in flow passage for connecting a collection portion of the plurality of supply flow passages and an inflow port of the hydraulic oil of the hydraulic cylinder; a plurality of discharge flow passages connected to each of the plurality of flow rate control valves; a meter-out flow passage for connecting a collection portion of the plurality of discharge flow passages and an outflow port of the hydraulic oil of the hydraulic cylinder; and a throttle arranged in the meter-out flow passage.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present disclosure relates to a work machine control system, a work machine, and a work machine control method. [Background technology]

[0002] In the technical field related to work machines, a hydraulic control device as disclosed in Patent Document 1 is known. In Patent Document 1, the hydraulic control device includes a control valve that adjusts the flow rate of hydraulic oil supplied to a hydraulic cylinder, and a variable throttle arranged in a meter-out flow path of the hydraulic cylinder. By disposing the variable throttle in the meter-out flow path, the flow rate of hydraulic oil discharged from the hydraulic cylinder to a tank is adjusted. By adjusting the flow rate of the hydraulic oil, the cylinder speed is adjusted. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-028358 A Summary of the Invention [Problem to be solved by the invention]

[0004] When multiple control valves are connected to one hydraulic cylinder, the hydraulic oil flowing out of the hydraulic cylinder is discharged to the tank through the meter-out passage. If the variable throttle is not properly positioned, the flow rate of the hydraulic oil may be excessively restricted. If the flow rate of the hydraulic oil is excessively restricted, the cylinder speed may decrease excessively, resulting in a decrease in work efficiency.

[0005] The present disclosure aims to suppress a decrease in work efficiency. [Means for solving the problem]

[0006] According to the present disclosure, there is provided a control system for a work machine comprising a plurality of hydraulic pumps that discharge hydraulic oil, a hydraulic cylinder that operates work machine elements, a plurality of flow control valves connected to each of the plurality of hydraulic pumps and adjusting the flow rate of the hydraulic oil supplied to the hydraulic cylinder, a plurality of supply flow paths connected to each of the plurality of flow control valves, a meter-in flow path connecting a junction of the plurality of supply flow paths and the hydraulic oil inlet of the hydraulic cylinder, a plurality of discharge flow paths connected to each of the plurality of flow control valves, a meter-out flow path connecting a junction of the plurality of discharge flow paths and the hydraulic oil outlet of the hydraulic cylinder, and a throttle arranged in the meter-out flow path. Effect of the Invention

[0007] According to the present disclosure, a decrease in work efficiency can be suppressed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing a work machine according to an embodiment. [Diagram 2] FIG. 2 is a schematic diagram for explaining the operation of the work machine according to the embodiment. [Diagram 3] FIG. 3 is a schematic diagram showing a control system for a work machine according to an embodiment. [Figure 4] FIG. 4 is a schematic diagram showing a control system for a work machine according to an embodiment. [Diagram 5] FIG. 5 is a functional block diagram showing the control device according to the embodiment. [Figure 6] FIG. 6 is a diagram for explaining correlation data according to the embodiment. [Figure 7] FIG. 7 is a flowchart showing a method for controlling a hydraulic excavator according to the embodiment. [Figure 8] FIG. 8 is a schematic diagram showing a control system for a work machine according to an embodiment. [Figure 9] FIG. 9 is a block diagram illustrating a computer system according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings, but the present disclosure is not limited thereto. The components of each embodiment described below can be appropriately combined. In addition, some components may not be used.

[0010] [Work machinery] 1 is a perspective view showing a work machine 100 according to an embodiment. In the embodiment, an example will be described in which the work machine 100 is a hydraulic excavator. In the following description, the work machine 100 will be appropriately referred to as the hydraulic excavator 100.

[0011] As shown in FIG. 1, a hydraulic excavator 100 includes a work machine 1, a hydraulic cylinder 2, a rotating body 3, a traveling body 4, and an operating device 5.

[0012] The rotating body 3 supports the work machine 1. The rotating body 3 rotates around a rotation axis RX. The rotating body 3 rotates by power generated by a rotation motor (not shown). The rotating body 3 has a cab 6 and a machine room 7. An operator of the hydraulic excavator 100 sits in the cab 6. A driver's seat 6S in which the operator is seated is provided in the cab 6.

[0013] The running body 4 supports the rotating body 3. The running body 4 has a pair of tracks 4C. The tracks 4C rotate by power generated by a travel motor (not shown). The hydraulic excavator 100 travels due to the rotation of the tracks 4C. The running body 4 may have tires attached to the axles.

[0014] The work machine 1 is supported by a rotating body 3. The work machine 1 includes a plurality of work machine elements that are relatively movable. The work machine elements of the work machine 1 include a boom 11 connected to the rotating body 3, an arm 12 connected to the boom 11, and a bucket 13 connected to the arm 12.

[0015] The boom 11 and the rotating body 3 are connected via a boom pin. The boom 11 is supported by the rotating body 3 so as to be rotatable about a rotation axis AX1.

[0016] The boom 11 and the arm 12 are connected via an arm pin. The arm 12 is supported by the boom 11 so as to be rotatable about a rotation axis AX2.

[0017] The arm 12 and the bucket 13 are connected via a bucket pin. The bucket 13 is supported by the arm 12 so as to be rotatable about a rotation axis AX3.

[0018] The rotation axis AX1, the rotation axis AX2, and the rotation axis AX3 are parallel. The rotation axis AX1 and an axis parallel to the revolving axis RX are perpendicular to each other. In the following description, the direction parallel to the revolving axis RX will be referred to as the up-down direction of the revolving body 3, the direction parallel to the rotation axis AX1 will be referred to as the vehicle width direction or left-right direction of the revolving body 3, and the direction perpendicular to both the rotation axis AX1 and the revolving axis RX will be referred to as the fore-aft direction of the revolving body 3. The direction in which the work machine 1 exists based on the revolving axis RX is the forward direction. The direction in which the machine room 7 exists based on the revolving axis RX is the rearward direction.

[0019] The hydraulic cylinders 2 operate the work machine elements based on hydraulic oil. A plurality of hydraulic cylinders 2 are provided to operate each of the plurality of work machine elements. The hydraulic cylinders 2 include a boom cylinder 21 that operates the boom 11, an arm cylinder 22 that operates the arm 12, and a bucket cylinder 23 that operates the bucket 13.

[0020] The operation device 5 is operated by the operator of the hydraulic excavator 100. The operation device 5 is operated to operate the work machine 1 and the rotating body 3. The operation device 5 is disposed in the operator's cab 6. The operation device 5 includes a plurality of operation levers. By operating the operation device 5, the work machine 1 and the rotating body 3 are operated.

[0021] [Working machine operation] 2 is a schematic diagram for explaining the operation of the work machine 1 according to the embodiment. The operating device 5 is operated to operate the work machine 1 and the revolving body 3. The operating device 5 is operated to drive the hydraulic cylinder 2 or the revolving motor (not shown). The hydraulic cylinder 2 is driven to operate the work machine 1. The revolving body 3 is operated to operate the revolving motor. The operating device 5 is operated to perform the raising operation of the boom 11, the lowering operation of the boom 11, the excavation operation of the arm 12, the dumping operation of the arm 12, the dumping operation of the bucket 13, and the excavation operation of the bucket 13. The operating device 5 is operated to perform the revolving operation of the revolving body 3.

[0022] The boom 11 is raised by the extension of the boom cylinder 21. The boom 11 is lowered by the contraction of the boom cylinder 21.

[0023] The arm 12 performs an excavation operation when the arm cylinder 22 extends, and performs a dump operation when the arm cylinder 22 retracts.

[0024] When the bucket cylinder 23 extends, the bucket 13 performs an excavation operation. When the bucket cylinder 23 retracts, the bucket 13 performs a dump operation.

[0025] When the rotation motor is driven, the rotating body 3 rotates.

[0026] [Control System] Fig. 3 is a schematic diagram showing a control system 10 of a hydraulic excavator 100 according to an embodiment. As shown in Fig. 3, the control system 10 includes a control device 9, an engine 30, a power transmission mechanism 31, a hydraulic pump 32, a first flow path 33, a second flow path 34, a tank 35, a hydraulic cylinder 2, a flow control valve 40, a bleed valve 50, a throttle 51, and a regeneration valve 52. The engine 30, the power transmission mechanism 31, the hydraulic pump 32, and the tank 35 are each disposed in a machine room 7 of a rotating body 3.

[0027] The engine 30 is a power source for the hydraulic excavator 100. An example of the engine 30 is a diesel engine.

[0028] The power transmission mechanism 31 transmits the power generated by the engine 30 to the hydraulic pump 32. In the embodiment, a plurality of hydraulic pumps 32 are provided. In the example shown in FIG. 3, six hydraulic pumps 32 are provided. The power transmission mechanism 31 distributes the power generated by the engine 30 to the plurality of hydraulic pumps 32.

[0029] The hydraulic pump 32 is driven by the power transmitted from the power transmission mechanism 31. The hydraulic pump 32 discharges hydraulic oil. In the embodiment, the hydraulic pump 32 is a variable displacement hydraulic pump.

[0030] The hydraulic cylinder 2 operates the work machine elements within a movable range based on the hydraulic oil supplied from the hydraulic pump 32. As described above, the hydraulic cylinder 2 includes the boom cylinder 21 that operates the boom 11, the arm cylinder 22 that operates the arm 12, and the bucket cylinder 23 that operates the bucket 13.

[0031] The hydraulic cylinder 2 has a bottom chamber 2A and a rod chamber 2B. When hydraulic oil is supplied to the bottom chamber 2A, the hydraulic cylinder 2 extends. When hydraulic oil is supplied to the rod chamber 2B, the hydraulic cylinder 2 contracts.

[0032] The first flow path 33 is connected to the discharge ports of the hydraulic pumps 32. In the example shown in Fig. 3, the first flow path 33 is connected to each of the discharge ports of the two hydraulic pumps 32. The hydraulic oil discharged from the discharge ports of the hydraulic pumps 32 can flow through the first flow path 33. The hydraulic oil discharged from the hydraulic pumps 32 and flowing through the first flow path 33 is supplied to the hydraulic cylinder 2.

[0033] The second flow path 34 is provided so as to branch off from the first flow path 33. The hydraulic oil discharged from the discharge port of the hydraulic pump 32 can flow through the second flow path 34. The hydraulic oil discharged from the hydraulic pump 32 and flowing through the second flow path 34 is discharged into a tank 35.

[0034] The flow control valve 40 adjusts the flow rate of the hydraulic oil supplied to the hydraulic cylinder 2 via the first flow path 33. The bottom chamber 2A of the hydraulic cylinder 2 is connected to the flow control valve 40 via the bottom flow path 36 and a collecting flow path 71. The rod chamber 2B of the hydraulic cylinder 2 is connected to the flow control valve 40 via the collecting flow path 72 and the rod flow path 37.

[0035] A plurality of flow rate control valves 40 are provided. The flow rate control valves 40 include a boom flow rate control valve 41 that adjusts the flow rate of hydraulic oil supplied to the boom cylinder 21, an arm flow rate control valve 42 that adjusts the flow rate of hydraulic oil supplied to the arm cylinder 22, and a bucket flow rate control valve 43 that adjusts the flow rate of hydraulic oil supplied to the bucket cylinder 23. The hydraulic oil discharged from the hydraulic pump 32 to the first flow path 33 is supplied to each of the boom flow rate control valve 41, the arm flow rate control valve 42, and the bucket flow rate control valve 43.

[0036] In the embodiment, a plurality of boom flow control valves 41, arm flow control valves 42, and bucket flow control valves 43 are provided. In the example shown in Fig. 3, three boom flow control valves 41 are provided. Three arm flow control valves 42 are provided. Three bucket flow control valves 43 are provided.

[0037] The flow control valve 40 is connected to each of the multiple hydraulic pumps 32. The three boom flow control valves 41 are connected to each of the multiple hydraulic pumps 32. The three arm flow control valves 42 are connected to each of the multiple hydraulic pumps 32. The three bucket flow control valves 43 are connected to each of the multiple hydraulic pumps 32.

[0038] Three collecting passages 71 are provided so as to be connected to the bottom chamber 2A of the boom cylinder 21, the bottom chamber 2A of the arm cylinder 22, and the bottom chamber 2A of the bucket cylinder 23, respectively.

[0039] Three collecting passages 72 are provided so as to be connected to the rod chamber 2B of the boom cylinder 21, the rod chamber 2B of the arm cylinder 22, and the rod chamber 2B of the bucket cylinder 23, respectively.

[0040] Nine bottom flow paths 36 are provided so as to be connected to the three boom flow control valves 41, the three arm flow control valves 42, and the three bucket flow control valves 43, respectively.

[0041] The bottom flow passages 36 connected to the three boom flow control valves 41 are connected to a collecting flow passage 71 connected to the bottom chamber 2A of the boom cylinder 21 via a collecting portion 36S.

[0042] The bottom flow passages 36 connected to the three arm flow control valves 42 are connected to a collecting passage 71 connected to the bottom chamber 2A of the arm cylinder 22 via a collecting portion 36S.

[0043] The bottom flow passages 36 connected to the three bucket flow rate control valves 43 are connected to a collecting flow passage 71 connected to the bottom chamber 2A of the bucket cylinder 23 via a collecting portion 36S.

[0044] Nine rod flow paths 37 are provided so as to be connected to the three boom flow control valves 41, the three arm flow control valves 42, and the three bucket flow control valves 43, respectively.

[0045] The rod flow paths 37 connected to the three boom flow control valves 41 are connected to a collecting flow path 72 connected to the rod chamber 2B of the boom cylinder 21 via a collecting portion 37S.

[0046] The rod flow paths 37 connected to the three arm flow control valves 42 are connected to a collecting flow path 72 connected to the rod chamber 2B of the arm cylinder 22 via a collecting portion 37S.

[0047] The rod passages 37 connected to the three bucket flow rate control valves 43 are connected to a collecting passage 72 connected to the rod chamber 2B of the bucket cylinder 23 via a collecting portion 37S.

[0048] That is, the bottom chamber 2A of the boom cylinder 21 is connected to each of the three boom flow control valves 41 via the collecting passage 71 and the bottom passage 36. The rod chamber 2B of the boom cylinder 21 is connected to each of the three boom flow control valves 41 via the collecting passage 72 and the rod passage 37.

[0049] The bottom chamber 2A of the arm cylinder 22 is connected to each of the three arm flow control valves 42 via the collecting passage 71 and the bottom passage 36. The rod chamber 2B of the arm cylinder 22 is connected to each of the three arm flow control valves 42 via the collecting passage 72 and the rod passage 37.

[0050] The bottom chamber 2A of the bucket cylinder 23 is connected to each of the three bucket flow control valves 43 via a collecting passage 71 and a bottom passage 36. The rod chamber 2B of the bucket cylinder 23 is connected to each of the three bucket flow control valves 43 via a collecting passage 72 and a rod passage 37.

[0051] The hydraulic pump 32 can supply hydraulic oil to each of the boom flow control valve 41, the arm flow control valve 42, and the bucket flow control valve 43 via the first flow path 33. A supply flow path 33A is connected to each of the boom flow control valve 41, the arm flow control valve 42, and the bucket flow control valve 43. The first flow path 33 is connected to each of the three supply flow paths 33A. The hydraulic oil discharged from the hydraulic pump 32 to the first flow path 33 is supplied to each of the boom flow control valve 41, the arm flow control valve 42, and the bucket flow control valve 43 via the supply flow path 33A.

[0052] The bleed valve 50 adjusts the flow rate of the hydraulic oil discharged to the tank 35 via the second flow path 34. The bleed valve 50 is disposed in the second flow path 34. The hydraulic pump 32 can supply the hydraulic oil to the bleed valve 50 via the second flow path 34. The second flow path 34 branches off from the first flow path 33 between the hydraulic pump 32 and the flow control valve 40. The hydraulic oil discharged from the hydraulic pump 32 to the second flow path 34 is supplied to the bleed valve 50 without being supplied to the flow control valve 40.

[0053] The bleed valve 50 has an inlet port Pe and an outlet port Pf.

[0054] The inflow port Pe is connected to the hydraulic pump 32 via the second flow path 34. The hydraulic oil discharged from the hydraulic pump 32 can flow into the bleed valve 50 from the inflow port Pe after circulating through the second flow path 34.

[0055] The outflow port Pf is connected to the tank 35 via a tank flow passage 39. The hydraulic oil flowing out from the outflow port Pf flows through the tank flow passage 39 and then is discharged into the tank 35.

[0056] The spool of the bleed valve 50 moves between a discharge position P4 where the hydraulic oil is discharged to the tank 35 and a stop position P5 where the hydraulic oil does not flow.

[0057] When the spool of the bleed valve 50 is located at the discharge position P4, the hydraulic oil discharged from the hydraulic pump 32 flows through the second flow path 34, then flows into the bleed valve 50 from the inlet port Pe, and flows out from the outlet port Pf. The hydraulic oil that flows out from the outlet port Pf flows through the tank flow path 39, and then is discharged into the tank 35.

[0058] When the spool of the bleed valve 50 is located in the stop position P5, the hydraulic oil cannot flow through the bleed valve 50.

[0059] The bleed valve 50 controls the flow rate of hydraulic oil discharged to the tank 35 by the amount of movement of the spool. The amount of movement of the spool adjusts the opening area of ​​the port through which the hydraulic oil flows in the bleed valve 50. By adjusting the opening area of ​​the bleed valve 50, the flow rate of hydraulic oil discharged to the tank 35 is adjusted.

[0060] The throttle 51 is arranged in the collecting flow path 71 or the collecting flow path 72. In the embodiment, the throttle 51 is arranged in the collecting flow path 71 connected to the bottom chamber 2A of the boom cylinder 21. The throttle 51 may be arranged in the collecting flow path 72 connected to the rod chamber 2B of the arm cylinder 22. The throttle 51 may be arranged in the collecting flow path 72 connected to the rod chamber 2B of the bucket cylinder 23. The throttle 51 adjusts the flow rate of hydraulic oil flowing through the collecting flow path 71 or the collecting flow path 72. The throttle 51 is provided in a collecting flow path that is affected by the weight (action of gravity) of the work machine element.

[0061] The regeneration valve 52 adjusts the regeneration flow rate of hydraulic oil regenerated from the collecting flow path 71 to the collecting flow path 72, or the regeneration flow rate of hydraulic oil regenerated from the collecting flow path 72 to the collecting flow path 71. In the embodiment, the regeneration valve 52 is arranged to adjust the regeneration flow rate of hydraulic oil regenerated from the collecting flow path 71 connected to the bottom chamber 2A of the boom cylinder 21 to the collecting flow path 72 connected to the rod chamber 2B of the boom cylinder 21. Note that the regeneration valve 52 may be arranged to adjust the regeneration flow rate of hydraulic oil regenerated from the collecting flow path 72 connected to the rod chamber 2B of the arm cylinder 22 to the collecting flow path 71 connected to the bottom chamber 2A of the arm cylinder 22.

[0062] FIG. 4 is a schematic diagram showing the control system 10 of the hydraulic excavator 100 according to the embodiment. FIG. 4 corresponds to a diagram in which the boom cylinder 21 and the boom flow control valve 41 are extracted from FIG. 3. In the example shown in FIG. 3, hydraulic oil from two hydraulic pumps 32 arranged in tandem is joined and supplied to a plurality of flow control valves 40 (41, 42, 43) arranged in parallel, but in the example shown in FIG. 4, there is only one hydraulic pump 32. The number of hydraulic pumps 32 is arbitrary. In the example shown in FIG. 3, a plurality of hydraulic pumps 32 are connected to the power transmission mechanism 31. The hydraulic oil discharged from the hydraulic pumps 32 arranged in tandem flows through one flow control valve 40, then flows and is joined, and is supplied to one hydraulic cylinder 2. A plurality of hydraulic circuits through which the hydraulic oil supplied to one hydraulic cylinder 2 flows are provided. 3, hydraulic oil from three flow control valves 40 (e.g., 41, 41, 41) provided in the respective hydraulic circuits is joined and supplied to one hydraulic cylinder 2 (e.g., boom cylinder 21), but this is not limited thereto. The number of flow control valves 40 that supply hydraulic oil to one hydraulic cylinder 2 is arbitrary.

[0063] As shown in FIG. 4, the control system 10 includes a plurality of hydraulic pumps 32 that discharge hydraulic oil, a hydraulic cylinder 2 that operates work machine elements, a plurality of flow control valves 40 that are connected to each of the plurality of hydraulic pumps 32 and adjust the flow rate of the hydraulic oil supplied to the hydraulic cylinder 2, a plurality of rod flow paths 37 connected to each of the plurality of flow control valves 40, a collecting flow path 72 that connects a collecting portion 37S of the plurality of rod flow paths 37 and an opening 2D of the rod chamber 2B of the hydraulic cylinder 2, a plurality of bottom flow paths 36 connected to each of the plurality of flow control valves 40, a collecting flow path 71 that connects a collecting portion 36S of the plurality of bottom flow paths 36 and an opening 2C of the bottom chamber 2A of the hydraulic cylinder 2, and a throttle 51 arranged in the collecting flow path 71.

[0064] The boom 11 is raised and lowered by the boom cylinder 21. FIG. 4 shows a state in which the boom cylinder 21 is retracted and the boom 11 is lowered. When the boom 11 is lowered, hydraulic oil flows into the rod chamber 2B of the boom cylinder 21 and flows out of the bottom chamber 2A of the boom cylinder 21. That is, the hydraulic oil discharged from the hydraulic pump 32 flows into the rod flow passage 37 via the boom flow control valve 41, flows through the collecting flow passage 72, and then flows into the rod chamber 2B via the opening 2D. The hydraulic oil flowing out from the opening 2C of the bottom chamber 2A of the hydraulic cylinder 2 flows through the collecting flow passage 71 and the bottom flow passage 36, and then is discharged into the tank 35 via the boom flow control valve 41.

[0065] In the following description, the rod flow path 37 will be appropriately referred to as the supply flow path 37, the opening 2D of the rod chamber 2B will be appropriately referred to as the inlet 2D, the collecting flow path 72 will be appropriately referred to as the meter-in flow path 72, the opening 2C of the bottom chamber 2A will be appropriately referred to as the outlet 2C, the collecting flow path 71 will be appropriately referred to as the meter-out flow path 71, and the bottom flow path 36 will be appropriately referred to as the discharge flow path 36.

[0066] The hydraulic pump 32 discharges hydraulic oil. A plurality of hydraulic pumps 32 are provided. In the example shown in Fig. 4, three hydraulic pumps 32 are provided. One hydraulic pump 32 is connected to one boom flow control valve 41. Note that, as shown in Fig. 3, two hydraulic pumps 32 may be connected to one boom flow control valve 41.

[0067] The boom cylinder 21 operates the boom 11. The boom 11 is raised and lowered by the boom cylinder 21. When the boom 11 is lowered, hydraulic oil flows into the rod chamber 2B from the inlet 2D, and hydraulic oil in the bottom chamber 2A flows out from the outlet 2C.

[0068] The boom flow control valve 41 adjusts the flow rate of hydraulic oil supplied to the boom cylinder 21. A plurality of boom flow control valves 41 are provided. In the example shown in Fig. 4, three boom flow control valves 41 are provided. The three boom flow control valves 41 are connected to the three hydraulic pumps 32, respectively. There is a one-to-one correspondence between the boom flow control valves 41 and the hydraulic pumps 32.

[0069] The supply flow passage 37 is connected to the boom flow control valve 41. A plurality of supply flow passages 37 are provided. In the example shown in Fig. 4, three supply flow passages 37 are provided. The three supply flow passages 37 are connected to the three boom flow control valves 41, respectively. There is a one-to-one correspondence between the supply flow passages 37 and the boom flow control valves 41.

[0070] One end of the supply passage 37 is connected to the boom flow control valve 41. The other end of the supply passage 37 is gathered at a gathering portion 37S. The other end of the supply passage 37 is connected to a meter-in passage 72 via the gathering portion 37S. The hydraulic oil that has flowed through each of the multiple supply passages 37 is joined in the meter-in passage 72.

[0071] The meter-in passage 72 is connected to the inlet 2D into which hydraulic oil flows when the boom 11 is lowered. The meter-in passage 72 connects the collection portion 37S of the three supply passages 37 and the hydraulic oil inlet 2D of the boom cylinder 21. The hydraulic oil that flows through each of the multiple supply passages 37 and joins together at the meter-in passage 72 flows through the meter-in passage 72, and then flows into the rod chamber 2B from the inlet 2D.

[0072] The discharge flow passage 36 is connected to the boom flow control valve 41. A plurality of discharge flow passages 36 are provided. In the example shown in Fig. 4, three discharge flow passages 36 are provided. The three discharge flow passages 36 are connected to the three boom flow control valves 41, respectively. There is a one-to-one correspondence between the discharge flow passages 36 and the boom flow control valves 41.

[0073] One end of the discharge flow passage 36 is connected to the boom flow control valve 41. The other end of the discharge flow passage 36 is collected at a collecting portion 36S. The other end of the discharge flow passage 36 is connected to a meter-out flow passage 71 via the collecting portion 36S. The hydraulic oil that has flowed through the meter-out flow passage 71 branches into each of the three discharge flow passages 36.

[0074] The meter-out flow passage 71 is connected to the outlet 2C from which the hydraulic oil flows out when the boom 11 is lowered. The meter-out flow passage 71 connects the collection portion 36S of the three discharge flow passages 36 and the hydraulic oil outlet 2C of the boom cylinder 21. The hydraulic oil that flows out from the outlet 2C of the bottom chamber 2A flows through the meter-out flow passage 71, then flows through each of the multiple discharge flow passages 36, and flows into each of the multiple boom flow control valves 41.

[0075] The boom flow control valve 41 (flow control valve 40) has a pump port Pa, a bottom port Pb, a rod port Pc, and a tank port Pd.

[0076] The supply passage 33A is connected to the pump port Pa. The pump port Pa is connected to the hydraulic pump 32 via the supply passage 33A. The hydraulic oil discharged from the hydraulic pump 32 can flow through the supply passage 33A and then flow into the flow control valve 40 from the pump port Pa.

[0077] The supply passage 37 is connected to the rod port Pc. The rod port Pc is connected to the rod chamber 2B of the hydraulic cylinder 2 via the supply passage 37 and the meter-in passage 72. The hydraulic oil flowing out from the rod port Pc can flow into the rod chamber 2B of the hydraulic cylinder 2 after circulating through the rod passage 37 and the meter-in passage 72.

[0078] The discharge passage 36 is connected to the bottom port Pb. The bottom port Pb is connected to the bottom chamber 2A of the hydraulic cylinder 2 via the discharge passage 36 and the meter-out passage 71. The hydraulic oil flowing out from the bottom chamber 2A of the hydraulic cylinder 2 can flow through the meter-out passage 71 and the discharge passage 36, and then flow into the flow control valve 40 from the bottom port Pb.

[0079] The tank port Pd is connected to the tank 35 via a discharge passage 38. The hydraulic oil flowing out from the tank port Pd flows through the discharge passage 38 and then is discharged into the tank 35.

[0080] The boom flow control valve 41 (flow control valve 40) is a flow control valve of a slide spool type that moves a rod-shaped spool to switch the flow rate and direction of the hydraulic oil supplied to the hydraulic cylinder 2. The axial movement of the spool switches between the supply of hydraulic oil to the bottom chamber 2A and the supply of hydraulic oil to the rod chamber 2B. The flow rate of the hydraulic oil supplied to the hydraulic cylinder 2 is adjusted based on the amount of movement of the spool.

[0081] The spool of the boom flow control valve 41 moves to a first operating position P1 at which hydraulic oil is supplied to the bottom chamber 2A of the hydraulic cylinder 2, a second operating position P2 at which hydraulic oil is supplied to the rod chamber 2B of the hydraulic cylinder 2, and a stop position P3 which is located between the first operating position P1 and the second operating position P2 and does not allow hydraulic oil to flow. In Fig. 4, the spool of the boom flow control valve 41 is located in the second operating position P2.

[0082] When the spool of the boom flow control valve 41 is disposed in the first operating position P1, the hydraulic oil discharged from the hydraulic pump 32 flows through the supply passage 33A, then flows into the boom flow control valve 41 from the pump port Pa, and flows out from the bottom port Pb. The hydraulic oil flowing out from the bottom port Pb flows through the bottom passage 36 and the collecting passage 71, and then flows into the bottom chamber 2A of the hydraulic cylinder 2. This causes the boom cylinder 21 to extend. When the boom cylinder 21 extends, the hydraulic oil flows out from the rod chamber 2B. The hydraulic oil flowing out from the rod chamber 2B of the boom cylinder 21 flows through the collecting passage 72 and the rod passage 37, then flows into the boom flow control valve 41 from the rod port Pc, and flows out from the tank port Pd. The hydraulic oil flowing out from the tank port Pd is discharged to the tank 35 via the discharge passage 38.

[0083] When the spool of the boom flow control valve 41 is disposed in the second operating position P2, the hydraulic oil discharged from the hydraulic pump 32 flows through the supply passage 33A, then flows into the boom flow control valve 41 from the pump port Pa, and flows out from the rod port Pc. The hydraulic oil flowing out from the rod port Pc flows through the rod passage 37 and the collecting passage 72, and then flows into the rod chamber 2B of the boom cylinder 21. This causes the boom cylinder 21 to retract. When the boom cylinder 21 retracts, the hydraulic oil flows out from the bottom chamber 2A. The hydraulic oil flowing out from the bottom chamber 2A of the boom cylinder 21 flows through the collecting passage 71 and the bottom passage 36, then flows into the boom flow control valve 41 from the bottom port Pb, and flows out from the tank port Pd. The hydraulic oil flowing out from the tank port Pd is discharged to the tank 35 via the discharge passage 38.

[0084] When the spool of the boom flow control valve 41 is located in the stop position P3, the hydraulic oil cannot flow through the boom flow control valve 41.

[0085] The boom flow control valve 41 controls the flow rate of hydraulic oil supplied to the boom cylinder 21 by the amount of movement of the spool. The amount of movement of the spool adjusts the opening area of ​​the port through which the hydraulic oil flows in the boom flow control valve 41. By adjusting the opening area of ​​the boom flow control valve 41, the flow rate of hydraulic oil supplied to the boom cylinder 21 is adjusted.

[0086] The orifice 51 is disposed in the meter-out passage 71. The orifice 51 is disposed in the meter-out passage 71 between the outlet 2C and the collecting section 36S. The orifice 51 adjusts the flow rate of hydraulic oil flowing through the meter-out passage 71. The opening area of ​​the orifice 51 is smaller than the opening area of ​​the outlet 2C. The opening area of ​​the orifice 51 is smaller than the maximum opening area of ​​the boom flow control valve 41. The orifice 51 regulates the flow rate of hydraulic oil flowing through the meter-out passage 71 when the boom 11 is lowered.

[0087] The control system 10 also includes a regeneration valve 52 that adjusts the regeneration flow rate of the hydraulic oil regenerated from the meter-out passage 71 to the meter-in passage 72. The regeneration valve 52 is disposed in a regeneration passage that connects an intermediate portion of the meter-out passage 71 and an intermediate portion of the meter-in passage 72.

[0088] The regeneration valve 52 has an inlet port Pg and an outlet port Ph.

[0089] The inflow port Pg is connected to the meter-out passage 71. The hydraulic oil flowing out from the outlet 2C can flow through at least a portion of the meter-out passage 71, and then flow into the regeneration valve 52 from the inflow port Pg.

[0090] The outflow port Ph is connected to the meter-in passage 72. The hydraulic oil that flows out from the outflow port Ph flows through at least a portion of the meter-in passage 72, and then flows into the rod chamber 2B from the inlet 2D.

[0091] During the lowering operation of the boom 11, the load pressure of the hydraulic oil may increase due to the weight (the action of gravity) of the boom 11. By utilizing the load pressure due to the weight of the boom 11, a portion of the hydraulic oil that has flowed out of the bottom chamber 2A is returned to the rod chamber 2B, so that the moving speed of the boom 11 can be increased.

[0092] The spool of the regeneration valve 52 moves between a stop position P6 where the hydraulic oil does not flow and a regeneration position P7 where the hydraulic oil is regenerated.

[0093] When the spool of the regeneration valve 52 is located in the stop position P6, hydraulic oil cannot flow through the regeneration valve 52.

[0094] When the spool of the regeneration valve 52 is disposed at the regeneration position P7, at least a portion of the hydraulic oil in the meter-out passage 71 can flow into the meter-in passage 72 via the regeneration valve 52.

[0095] The regeneration valve 52 controls the regeneration flow rate, which indicates the flow rate of hydraulic oil supplied from the meter-out passage 71 to the meter-in passage 72, by the amount of movement of the spool. The opening area of ​​the port through which the hydraulic oil flows in the regeneration valve 52 is adjusted by the amount of movement of the spool. The regeneration flow rate is adjusted by adjusting the opening area of ​​the regeneration valve 52.

[0096] The control system 10 also includes a suction valve 53 disposed between the supply passage 37 and the tank 35. The suction valve 53 allows hydraulic oil to flow from the tank 35 to the supply passage 37 when the pressure difference between the supply passage 37 and the tank 35 becomes equal to or greater than a predetermined specified value. An inflow port Pi of the suction valve 53 is connected to the tank 35. An outflow port Pj of the suction valve 53 is connected to the supply passage 37.

[0097] The cylinder speed of the boom cylinder 21 is determined based on the operation amount of the operating device 5. The larger the operation amount of the operating device 5, the higher the cylinder speed, and the smaller the operation amount of the operating device 5, the lower the cylinder speed. In the lowering operation of the boom 11, the weight of the boom 11 (the action of gravity) may cause the cylinder speed of the boom cylinder 21 to be higher than the cylinder speed specified based on the operation amount of the operating device 5. That is, in the lowering operation of the boom 11, the boom cylinder 21 may suddenly retract. If the boom cylinder 21 suddenly retracts due to the weight of the boom 11, even if the hydraulic oil is discharged from the hydraulic pump 32, the flow rate of the hydraulic oil supplied to the rod chamber 2B of the boom cylinder 21 may be insufficient, and the pressure of the supply flow path 37 and the meter-in flow path 72 may suddenly drop. If the hydraulic oil supplied from the hydraulic pump 32 is insufficient, a cavitation phenomenon in which air bubbles are generated in the hydraulic oil may occur. By providing the suction valve 53, when the pressure in the supply passage 37 and the meter-in passage 72 suddenly drops and the pressure difference between the supply passage 37 and the tank 35 reaches or exceeds a specified value, the suction valve 53 opens and hydraulic oil is supplied from the tank 35 to the supply passage 37 via the suction valve 53. As a result, hydraulic oil is supplied to the supply passage 37 from both the hydraulic pump 32 and the suction valve 53. This prevents a shortage of hydraulic oil and suppresses the occurrence of cavitation.

[0098] The control system 10 also includes a pressure sensor 61 that detects the pressure of hydraulic oil discharged from the boom cylinder 21, a pressure sensor 62 that detects the pressure of hydraulic oil flowing into the boom cylinder 21, and a pressure sensor 63 that detects the pressure of the hydraulic oil after passing through the orifice 51.

[0099] The pressure sensor 61 detects the pressure of the hydraulic oil flowing through the meter-out passage 71. The pressure sensor 61 detects the pressure of the hydraulic oil in the meter-out passage 71 between the outlet 2C and the throttle 51. In the embodiment, the pressure sensor 61 detects the pressure of the hydraulic oil in the meter-out passage 71 between the outlet 2C and the inlet port Pg of the regeneration valve 52.

[0100] The pressure sensor 62 detects the pressure of the hydraulic oil flowing through the meter-in passage 72. The pressure sensor 62 detects the pressure of the hydraulic oil between the outlet port Ph of the regeneration valve 52 and the inlet 2D.

[0101] The pressure sensor 63 detects the pressure of the hydraulic oil flowing through the meter-out passage 71. The pressure sensor 63 detects the pressure of the hydraulic oil in the meter-out passage 71 between the throttle 51 and the collecting portion 36S.

[0102] [Control device] 5 is a functional block diagram showing the control device 9 according to the embodiment. The control device 9 includes a computer system. The control device 9 is connected to each of the operation device 5, the pressure sensor 61, the pressure sensor 62, and the pressure sensor 63 via communication lines. The control device 9 is also connected to each of the hydraulic pump 32, the flow control valve 40, and the regeneration valve 52 via control lines.

[0103] The control device 9 has a correlation data memory unit 9A, an operation command acquisition unit 9B, a pressure data acquisition unit 9C, a target meter-in flow rate calculation unit 9D, a target regeneration flow rate calculation unit 9E, a target pump flow rate calculation unit 9F, a target meter-out flow rate calculation unit 9G, a target pump capacity calculation unit 9H, a control valve opening area calculation unit 9I, a regeneration valve opening area calculation unit 9J, a pump control unit 9K, a control valve control unit 9L, and a regeneration valve control unit 9M.

[0104] The correlation data storage unit 9A stores correlation data between the operation amount of the operating device 5 and a target meter-in flow rate indicating a target flow rate of the hydraulic oil flowing into the inlet 2D of the hydraulic cylinder 2.

[0105] The operation command acquisition unit 9B acquires an operation command for the operation device 5. The operation command for the operation device 5 includes an operation amount of the operation device 5. The operation amount of the operation device 5 includes a tilt angle of the operation lever. When the operation amount of the operation device 5 indicates a maximum value, the operation amount is 100[%]. When the operation device 5 is not operated, the operation amount is 0[%].

[0106] Fig. 6 is a diagram for explaining correlation data according to the embodiment. As shown in Fig. 6, correlation data indicating the relationship between the operation amount of the operating device 5 and the target meter-in flow rate Qcyl flowing into the inlet 2D of the flow control valve 40 is determined in advance. The correlation data is stored in a correlation data storage unit 9A.

[0107] As shown in FIG. 6, the correlation data is determined so that the smaller the amount of operation of the operating device 5, the smaller the target meter-in flow rate Qcyl becomes, and the greater the amount of operation of the operating device 5, the larger the target meter-in flow rate Qcyl becomes.

[0108] In the embodiment, the target meter-in flow rate Qcyl is defined by a target pump flow rate Qp, a suction flow rate, and a target regeneration flow rate Qr. The target pump flow rate Qp indicates a target flow rate of hydraulic oil discharged from the hydraulic pump 32. The suction flow rate is the flow rate of hydraulic oil sucked from the tank 35 into the supply flow path 37 via the suction valve 53. The target regeneration flow rate Qr indicates a target flow rate of hydraulic oil regenerated from the meter-out flow path 71 to the meter-in flow path 72 via the regeneration valve 52.

[0109] When the amount of operation of the operating device 5 is less than a predetermined value Ms, the target meter-in flow rate Qcyl is defined by the sum of the target pump flow rate Qp and the suction flow rate. When the amount of operation of the operating device 5 is equal to or greater than the value Ms, the target meter-in flow rate Qcyl is defined by the sum of the target pump flow rate Qp, the suction flow rate and the target regeneration flow rate Qr.

[0110] The correlation data is determined such that the smaller the amount of operation of the operating device 5, the smaller the target pump flow rate Qp becomes, and the greater the amount of operation of the operating device 5, the greater the target pump flow rate Qp becomes.

[0111] In addition, when the amount of operation of the operating device 5 is equal to or greater than the value Ms, the correlation data is determined so that the smaller the amount of operation of the operating device 5, the smaller the target regeneration flow rate Qr becomes, and the greater the amount of operation of the operating device 5, the larger the target regeneration flow rate Qr becomes.

[0112] The pressure data acquisition unit 9C acquires detection data of the pressure sensor 61, detection data of the pressure sensor 62, and detection data of the pressure sensor 63. The pressure sensor 61 detects the pressure of the hydraulic oil flowing out from the outlet 2C of the boom cylinder 21. In the embodiment, the pressure sensor 61 detects the pressure of the hydraulic oil in the meter-out passage 71 between the outlet 2C and the inlet port Pg of the regeneration valve 52. The pressure sensor 62 detects the pressure of the hydraulic oil flowing into the inlet 2D of the hydraulic cylinder 2. In the embodiment, the pressure sensor 62 detects the pressure of the hydraulic oil between the outlet port Ph and the inlet 2D of the regeneration valve 52. The pressure sensor 63 detects the pressure of the hydraulic oil flowing through the meter-out passage 71. In the embodiment, the pressure sensor 63 detects the pressure of the hydraulic oil in the meter-out passage 71 between the throttle 51 and the collecting section 36S. The pressure data acquisition unit 9C acquires each of the detection data of the pressure sensor 61, detection data of the pressure sensor 62, and detection data of the pressure sensor 63.

[0113] The target meter-in flow rate calculation unit 9D calculates the target meter-in flow rate Qcyl [l / min.] based on the correlation data stored in the correlation data storage unit 9A and the operation command (operation amount) of the operation device 5 acquired by the operation command acquisition unit 9B.

[0114] The target regeneration flow rate calculation unit 9E calculates the target regeneration flow rate Qr [l / min.] of the hydraulic oil based on the target meter-in flow rate Qcyl calculated by the target meter-in flow rate calculation unit 9D. The target regeneration flow rate calculation unit 9E calculates the target regeneration flow rate Qr based on equation (1).

[0115]

number

[0116] In equation (1), Qstart is the regeneration start flow rate and is a threshold value related to the target meter-in flow rate Qcyl. As shown in FIG. 6, the regeneration start flow rate Qstart corresponds to the target meter-in flow rate Qcyl when the operation amount of the operation device 5 is the value Ms. The value Ms and the regeneration start flow rate Qstart are arbitrarily determined. Kr indicates the regeneration flow rate ratio. The regeneration flow rate ratio Kr is a unique value related to the regeneration valve 52 and is known data.

[0117] The target pump flow rate calculation unit 9F calculates the target pump flow rate Qp [l / min.] based on the target meter-in flow rate Qcyl calculated by the target meter-in flow rate calculation unit 9D and the target regeneration flow rate Qr calculated by the target regeneration flow rate calculation unit 9E. The target pump flow rate calculation unit 9F calculates the target pump flow rate Qp based on equation (2).

[0118]

number

[0119] In formula (2), Ks represents the suction valve flow ratio. The suction valve flow ratio Kw is a specific value related to the suction valve 53 and is known data.

[0120] The target meter-out flow rate calculation unit 9G calculates a target meter-out flow rate Qo [l / min.] indicating a target flow rate of the hydraulic oil flowing out from the outlet 2C of the hydraulic cylinder 2, based on the correlation data stored in the correlation data storage unit 9A and the operation command (operation amount) of the operation device 5 acquired by the operation command acquisition unit 9B. The target meter-out flow rate calculation unit 9G calculates the target meter-out flow rate Qo based on equation (3).

[0121]

number

[0122] In formula (3), Ao / Ai indicates the pressure-receiving area ratio of the hydraulic cylinder 2. The pressure-receiving area ratio Ao / Ai is an inherent value related to the hydraulic cylinder 2 and is known data.

[0123] The target pump capacity calculation unit 9H calculates the target capacity q [cc / rev] of the hydraulic pump 32 based on the target pump flow rate Qp calculated by the target pump flow rate calculation unit 9F. The target pump capacity calculation unit 9H calculates the target capacity q of the hydraulic pump 32 based on equation (4).

[0124]

number

[0125] In formula (4), Ne is the rotation speed [rpm] of the engine 30, and h is the gear ratio of the power transmission mechanism 31.

[0126] The control valve opening area calculation unit 9I calculates a target opening area of ​​the flow control valve 40 based on the target meter-out flow rate Qo calculated by the target meter-out flow rate calculation unit 9G. In the embodiment, the control valve opening area calculation unit 9I calculates the target opening area Ao of the flow control valve 40 based on the target meter-out flow rate Qo calculated by the target meter-out flow rate calculation unit 9G, the opening area As of the orifice 51, the pressure Po of the hydraulic oil flowing out from the hydraulic cylinder 2, the pressure Pa of the hydraulic oil between the orifice 51 and the flow control valve 40, and the pressure Pt of the tank 35.

[0127] When the flow coefficient of the throttle valve is Cs, the opening area of ​​the throttle 51 is As, the pressure of the hydraulic oil flowing out of the hydraulic cylinder 2 is Po, and the pressure of the hydraulic oil between the throttle 51 and the flow control valve 40 is Pa, the target meter-out flow rate Qo can be expressed by equation (5).

[0128]

number

[0129] In addition, when the flow coefficient of the flow control valve 40 is Co, the target opening area of ​​the flow control valve 40 is Ao, the pressure of the hydraulic oil between the orifice 51 and the flow control valve 40 is Pa, and the pressure of the hydraulic oil in the tank 35 is Pt, the target meter-out flow rate Qo can be expressed by equation (6).

[0130]

number

[0131] The pressure Po is detected by the pressure sensor 61 and acquired by the pressure data acquisition unit 9C. The pressure Pa is detected by the pressure sensor 63 and acquired by the pressure data acquisition unit 9C. The pressure Pt can be regarded as atmospheric pressure. The flow coefficient Cs is an inherent value related to the restrictor 51 and is known data. The flow coefficient Co is an inherent value related to the flow control valve 40 and is known data.

[0132] Equation (7) is derived by eliminating Pa from equations (5) and (6). A control valve opening area calculation unit 9I calculates a target opening area Ao of the flow control valve 40 based on equation (7).

[0133]

number

[0134] The target opening area Ao indicates the total target opening area of ​​the three flow control valves 40. When the target opening area of ​​each of the three flow control valves 40 is Ao[i], the control valve opening area calculation unit 9I calculates the target opening area Ao[i] of each flow control valve 40 based on equation (8).

[0135]

number

[0136] In formula (8), Qo[i] is the target meter-out flow rate of the flow control valve 40[i]. In the embodiment, three flow control valves 40[1], 40[2], and 40[3] are provided for one hydraulic cylinder 2. Qo[1] is the target meter-out flow rate of the first flow control valve 40[1]. Qo[2] is the target meter-out flow rate of the second flow control valve 40[2]. Qo[3] is the target meter-out flow rate of the third flow control valve 40[3].

[0137] The regeneration valve opening area calculation unit 9J calculates the target opening area Ar of the regeneration valve 52 based on the target regeneration flow rate Qr calculated by the target regeneration flow rate calculation unit 9E, the pressure Pi of the hydraulic oil flowing into the inlet 2D, and the pressure Po of the hydraulic oil flowing out from the outlet 2C. The regeneration valve opening area calculation unit 9J calculates the target opening area Ar of the regeneration valve 52 based on formula (9).

[0138]

number

[0139] In equation (9), Pi is the pressure of the hydraulic oil flowing into the hydraulic cylinder 2. The pressure Pi is detected by the pressure sensor 62 and acquired by the pressure data acquisition unit 9C. Cr is the flow coefficient of the regeneration valve 52. The flow coefficient Cr is an inherent value related to the regeneration valve 52 and is known data.

[0140] The pump control unit 9K outputs a control command to control the hydraulic pump 32 so that the capacity of the hydraulic pump 32 becomes the target capacity q calculated by the target pump capacity calculation unit 9H. The hydraulic pump 32 has a swash plate that changes the capacity. The pump control unit 9K outputs a control command to control the angle of the swash plate so that the capacity becomes the target capacity q.

[0141] The control valve control unit 9L outputs a control command to control the flow control valve 40 so that the flow control valve 40 becomes the target opening area Ao of the flow control valve 40 calculated by the control valve opening area calculation unit 9I. The opening area of ​​the flow control valve 40 is adjusted by the amount of movement of the spool. The control valve control unit 9L outputs a control command to the electromagnetic proportional control valve that adjusts the amount of movement of the spool so that the opening area becomes the target opening area Ao.

[0142] The regeneration valve control unit 9M outputs a control command to control the regeneration valve 52 so that the regeneration valve 52 has the target opening area Ar of the regeneration valve 52 calculated by the regeneration valve opening area calculation unit 9J.

[0143] [Method of controlling a work machine] Fig. 7 is a flowchart showing a method for controlling the hydraulic excavator 100 according to the embodiment. In the explanation using Fig. 7, a method for controlling the boom 11 and the boom cylinder 21 will be mainly explained.

[0144] The operator operates the operation device 5 to drive the boom cylinder 21. The boom cylinder 21 moves the boom 11 within a movable range.

[0145] The operation device 5 outputs an operation command when operated by the driver. The operation command includes an operation amount of the operation device 5. The operation command acquisition unit 9B acquires the operation amount of the operation device 5 (step S10).

[0146] The target meter-in flow rate calculation unit 9D calculates the target meter-in flow rate Qcyl based on the correlation data stored in the correlation data storage unit 9A and the operation amount of the operation device 5 acquired by the operation command acquisition unit 9B (step S20).

[0147] As shown in Fig. 6, correlation data indicating the relationship between the amount of operation of the operating device 5 and the target meter-in flow rate Qcyl is stored in the correlation data storage unit 9A. The correlation data is set in advance. As shown in Fig. 6, the correlation data is determined such that the target meter-in flow rate Qcyl increases as the amount of operation of the operating device 5 increases.

[0148] The target regeneration flow rate calculation unit 9E calculates the target regeneration flow rate Qr based on the target meter-in flow rate Qcyl. The target regeneration flow rate calculation unit 9E calculates the target regeneration flow rate Qr based on the above-mentioned formula (1) (step S30).

[0149] The regeneration valve 52 is controlled to close when the target meter-in flow rate Qcyl is less than the regeneration start flow rate Qstart, and to open when the target meter-in flow rate Qcyl is equal to or greater than the regeneration start flow rate Qstart. That is, in Fig. 6, when the operation amount of the operation device 5 is between 0[%] and Ms[%], the opening of the regeneration valve 52 is closed. When the operation amount of the operation device 5 becomes equal to or greater than Ms[%] and the target meter-in flow rate Qcyl becomes equal to or greater than the regeneration start flow rate Qstart, the regeneration valve 52 opens.

[0150] The target pump flow rate calculation unit 9F calculates the target pump flow rate Qp based on the target meter-in flow rate Qcyl and the target regeneration flow rate Qr. The target pump flow rate calculation unit 9F calculates the target pump flow rate Qp based on the above-mentioned formula (2) (step S40).

[0151] The target meter-out flow rate calculation unit 9G calculates the target meter-out flow rate Qo based on the target meter-in flow rate Qcyl and the target regeneration flow rate Qr. The target meter-out flow rate calculation unit 9G calculates the target meter-out flow rate Qo based on the above-mentioned formula (3) (step S50).

[0152] Based on the target pump flow rate Qp, the target pump displacement calculation unit 9H calculates the target displacement q [cc / rev] of the hydraulic pump 32. Based on the above-mentioned formula (4), the target pump displacement calculation unit 9H calculates the target displacement q of the hydraulic pump 32 (step S60).

[0153] The control valve opening area calculation unit 9I calculates the target opening area Ao of the boom flow control valve 41 based on the target meter-out flow rate Qo, the opening area As of the throttle valve, the pressure Po of the hydraulic oil flowing out from the hydraulic cylinder 2, the pressure Pa of the hydraulic oil between the throttle valve and the flow control valve 40, and the pressure Pt of the tank 35. The control valve opening area calculation unit 9I calculates the target opening area Ao of the boom flow control valve 41 based on the above-mentioned equations (5), (6), and (7) (step S70).

[0154] The target opening area Ao indicates the total target opening area of ​​the three boom flow control valves 41. When the target opening area of ​​each of the three boom flow control valves 41 is Ao[i], the control valve opening area calculation unit 9I calculates the target opening area Ao[i] of each of the three boom flow control valves 41 based on the above-mentioned formula (8) (step S80).

[0155] Based on the target regeneration flow rate Qr, the regeneration valve opening area calculation unit 9J calculates the target opening area Ar of the regeneration valve 52. Based on the above-mentioned formula (9), the regeneration valve opening area calculation unit 9J calculates the target opening area Ar of the regeneration valve 52 (step S90).

[0156] The pump control unit 9K outputs a control command to control the hydraulic pump 32 so that the hydraulic pump 32 reaches the target displacement q calculated in step S60. The hydraulic pump 32 has a swash plate that changes the displacement. The pump control unit 9K outputs a control command to control the angle of the swash plate so that the displacement reaches the target displacement q (step S100).

[0157] The control valve control unit 9L outputs a control command to control the boom flow control valve 41[i] so that each of the multiple boom flow control valves 41[i] becomes the target opening area Ao[i] calculated in step S80. The opening area of ​​the boom flow control valve 41 is adjusted by the amount of movement of the spool. The control valve control unit 9L outputs a control command to the electromagnetic proportional control valve that adjusts the amount of movement of the spool so that the opening area becomes the target opening area Ao[i] (step S110).

[0158] The regeneration valve control unit 9M outputs a control command to control the regeneration valve 52 so that the regeneration valve 52 has the target opening area Ar calculated in step S90 (step S120).

[0159] [Distribution of hydraulic oil to multiple hydraulic cylinders] 3, the hydraulic oil discharged from the hydraulic pump 32 is distributed through the first flow path 33 to each of the boom flow control valve 41, the arm flow control valve 42, and the bucket flow control valve 43. Hereinafter, the distribution of the hydraulic oil to the multiple hydraulic cylinders 2 will be described.

[0160] Fig. 8 is a schematic diagram showing the control system 10 of the hydraulic excavator 100 according to the embodiment. Fig. 8 corresponds to a diagram in which the boom cylinder 21, the arm cylinder 22, the boom flow control valve 41, and the arm flow control valve 42 are extracted from Fig. 3.

[0161] The work machine elements include a boom 11 and an arm 12. The hydraulic cylinder 2 includes a boom cylinder 21 that operates the boom 11 and an arm cylinder 22 that operates the arm 12.

[0162] The flow control valve 40 includes a first group of flow control valves 410 consisting of a plurality (three) of boom flow control valves 41 with a set priority, and a second group of flow control valves 420 consisting of a plurality (three) of arm flow control valves 42 with a set priority. The first group of flow control valves 410 adjusts the flow rate of hydraulic oil supplied to the boom cylinder 21. The second group of flow control valves 420 adjusts the flow rate of hydraulic oil supplied to the arm cylinder 22. The priority is a predetermined value that specifies which hydraulic cylinder 2 is to be given priority in the supply of hydraulic oil to each flow control valve 40. Note that, although the priority is specified in this embodiment, the hydraulic oil may be supplied equally from each flow control valve 40 without specifying the priority.

[0163] The first group of flow control valves 410 is composed of the boom flow control valve 41[1], the boom flow control valve 41[2], and the boom flow control valve 41[3]. In the first group of flow control valves 410, the boom flow control valve 41[1] has the highest priority, the boom flow control valve 41[2] has the second highest priority after the boom flow control valve 41[1], and the boom flow control valve 41[3] has the lowest priority.

[0164] The second group of flow control valves 420 is composed of the arm flow control valve 42[1], the arm flow control valve 42[2], and the arm flow control valve 42[3]. In the second group of flow control valves 420, the arm flow control valve 42[3] has the highest priority, the arm flow control valve 42[2] has the next highest priority after the arm flow control valve 42[1], and the arm flow control valve 42[1] has the lowest priority.

[0165] The control device 9 has a distribution control unit 9N that controls the opening area of ​​the first group of flow control valves 410 based on the priority of the first group of flow control valves 410 and the required flow rate of hydraulic oil for the boom cylinder 21.

[0166] In the example shown in FIG. 8, the required flow rate of hydraulic oil for the boom cylinder 21 is 1500 [L] per minute, the required flow rate of hydraulic oil for the arm cylinder 22 is 1500 [L] per minute, and 1000 [L] of hydraulic oil is discharged per minute from each of the three hydraulic pumps 32.

[0167] The distribution control unit 9N outputs a control command to adjust the opening area of ​​the first group of flow control valves 410 so that 1000 [L] of hydraulic oil is supplied per minute from the boom flow control valve 41[1] to the boom cylinder 21, 500 [L] of hydraulic oil is supplied per minute from the boom flow control valve 41[2] to the boom cylinder 21, and hydraulic oil is not supplied from the boom flow control valve 41[3] to the boom cylinder 21. That is, the distribution control unit 9N outputs a control command to adjust the opening area of ​​the first group of flow control valves 410 so that the higher the priority of the first group of flow control valves 410, the greater the flow rate of hydraulic oil supplied from the boom flow control valve 41[i] to the boom cylinder 21, and the lower the priority of the first group of flow control valves 410, the less the flow rate of hydraulic oil supplied from the boom flow control valve 41[i] to the boom cylinder 21.

[0168] The distribution control unit 9N also outputs a control command to adjust the opening area of ​​the second group of flow control valves 420 so that 1000 [L] of hydraulic oil is supplied per minute from the arm flow control valve 42[3] to the arm cylinder 22, 500 [L] of hydraulic oil is supplied per minute from the arm flow control valve 42[2] to the arm cylinder 22, and hydraulic oil is not supplied from the arm flow control valve 42[1] to the arm cylinder 22. That is, the distribution control unit 9N outputs a control command to adjust the opening area of ​​the second group of flow control valves 420 so that the higher the priority of the second group of flow control valves 420, the higher the flow rate of hydraulic oil supplied from the arm flow control valve 42[i] to the arm cylinder 22 becomes, and the lower the priority of the second group of flow control valves 420, the lower the flow rate of hydraulic oil supplied from the arm flow control valve 42[i] to the arm cylinder 22 becomes.

[0169] [Computer System] FIG. 9 is a block diagram showing a computer system 1000 according to an embodiment. The above-mentioned control device 9 includes the computer system 1000. The computer system 1000 has a processor 1001 such as a CPU (Central Processing Unit), a main memory 1002 including a non-volatile memory such as a ROM (Read Only Memory) and a volatile memory such as a RAM (Random Access Memory), a storage 1003, and an interface 1004 including an input / output circuit. The functions of the control device 9 are stored in the storage 1003 as a computer program. The processor 1001 reads the computer program from the storage 1003, expands it in the main memory 1002, and executes the above-mentioned processing according to the computer program. The computer program may be distributed to the computer system 1000 via a network.

[0170] According to the above-described embodiment, the computer program can execute the following operations: acquire an operation command output from the operating device 5; calculate a target meter-out flow rate Qo indicating a target flow rate of hydraulic oil flowing out from the outlet 2C of the hydraulic cylinder 2 based on the operation command and correlation data between the operation amount of the operating device 5 and the target meter-in flow rate Qcyl indicating a target flow rate of hydraulic oil flowing into the inlet 2D of the hydraulic cylinder 2; calculate a target opening area of ​​the flow control valve 40 that adjusts the flow rate of hydraulic oil supplied to the hydraulic cylinder 2 based on the target meter-out flow rate Qo; and output a control command so that the flow control valve 40 becomes the target opening area of ​​the flow control valve 40.

[0171] [effect] As described above, according to the embodiment, the control system 10 includes a plurality of hydraulic pumps 32 that discharge hydraulic oil, a boom cylinder 21 that operates the boom 11, a plurality of boom flow control valves 41 that are connected to the plurality of hydraulic pumps 32, respectively, and adjust the flow rate of hydraulic oil supplied to the boom cylinder 21, a plurality of supply flow paths 37 that are connected to the plurality of boom flow control valves 41, respectively, a meter-in flow path 72 that connects a collection section 37S of the plurality of supply flow paths 37 and a hydraulic oil inlet 2D of the boom cylinder 21, a plurality of discharge flow paths 36 that are connected to the plurality of boom flow control valves 41, respectively, a meter-out flow path 71 that connects a collection section 36S of the plurality of discharge flow paths 36 and a hydraulic oil outlet 2C of the boom cylinder 21, and a throttle 51 disposed in the meter-out flow path 71. When a plurality of boom flow control valves 41 are connected to one boom cylinder 21, the hydraulic oil flowing out from the boom cylinder 21 is discharged to the tank 35 via the meter-out flow path 71. By arranging the throttle 51 in the meter-out flow path 71, excessive restriction of the flow rate of the hydraulic oil discharged from the boom cylinder 21 is suppressed. For example, since the flow rate of the hydraulic oil discharged from the boom cylinder 21 is not excessively restricted when the throttle 51 is arranged only in the meter-out flow path 71 compared to when the throttle 51 is arranged in each of the multiple discharge flow paths 36, the cylinder speed of the boom cylinder 21 is suppressed from being excessively reduced below the cylinder speed specified by the operating device 5. Therefore, a decrease in work efficiency is suppressed.

[0172] The control device 9 includes a correlation data storage unit 9A that stores correlation data between the operation amount of the operating device 5 and the target meter-in flow rate Qcyl flowing into the inlet 2D of the boom cylinder 21, an operation command acquisition unit 9B that acquires an operation command for the operating device 5, a target meter-out flow rate calculation unit 9G that calculates a target meter-out flow rate Qo of the hydraulic oil flowing out from the outlet 2C based on the correlation data and the operation command, a control valve opening area calculation unit 9I that calculates a target opening area Ao of the boom flow control valve 41 based on the target meter-out flow rate Qo, and a control valve control unit 9L that outputs a control command so that the boom flow control valve 41 becomes the target opening area Ao of the boom flow control valve 41. Since the target opening area Ao of the boom flow control valve 41 is controlled based on the target meter-out flow rate Qo, the cylinder speed of the boom cylinder 21 is prevented from excessively decreasing below the cylinder speed specified by the operating device 5. Therefore, a decrease in work efficiency is suppressed.

[0173] The control device 9 has a target regeneration flow rate calculation unit 9E that calculates a target regeneration flow rate Qr of the hydraulic oil based on the target meter-in flow rate Qcyl, a regeneration valve opening area calculation unit 9J that calculates a target opening area Ar of the regeneration valve 52 based on the target regeneration flow rate Qr, the pressure Pi of the hydraulic oil flowing into the inlet 2D of the boom cylinder 21, and the pressure Po of the hydraulic oil flowing out from the outlet 2C of the boom cylinder 21, and a regeneration valve control unit 9M that outputs a control command so that the regeneration valve 52 becomes the target opening area Ar of the regeneration valve 52. Since the target opening area of ​​the regeneration valve 52 is controlled based on the target regeneration flow rate Qr, it is possible to prevent the cylinder speed of the boom cylinder 21 from being excessively lowered below the cylinder speed specified by the operating device 5. Therefore, a decrease in work efficiency is suppressed.

[0174] The flow control valve 40 includes a first group of flow control valves 410 consisting of a plurality of boom flow control valves 41 with a set priority, and a second group of flow control valves 420 consisting of a plurality of arm flow control valves 42 with a set priority. The control device 9 has a distribution control unit 9N that controls the opening area of ​​the first group of flow control valves 410 based on the priority of the first group of flow control valves 410, the required flow rate of hydraulic oil for the boom cylinder 21, and the required flow rate of hydraulic oil for the arm cylinder 22. This makes it possible to supply hydraulic oil to each of the plurality of hydraulic cylinders 2 at an appropriate flow rate.

[0175] [Other embodiments] In the above-described embodiment, the work machine 100 is a hydraulic excavator. The work machine 100 may be any machine having a work implement 1, and may be a wheel loader or a bulldozer.

[0176] In the above embodiment, each flow control valve 40 has a priority for supplying hydraulic oil to the boom cylinder 21 and the arm cylinder 22, but this is not limited to the above. A priority may be given to the bucket cylinder 23.

[0177] In the above embodiment, three pressure sensors are provided to detect the pressure of the hydraulic oil, but the present invention is not limited to this. It is sufficient if the flow rate can be calculated from the pressure of the hydraulic oil flowing in and out of the hydraulic cylinder 20. [Explanation of symbols]

[0178] 1...working machine, 2...hydraulic cylinder, 2A...bottom chamber, 2B...rod chamber, 2C...outlet (opening), 2D...inlet (opening), 3...rotating body, 4...running body, 4C...track, 5...operating device, 6...operator's cab, 6S...operator's seat, 7...machine room, 9...control device, 9A...correlation data storage unit, 9B...operation command acquisition unit, 9C...pressure data acquisition unit, 9D...target meter-in flow rate calculation unit, 9E...target regeneration flow rate calculation unit, 9F...target pump flow rate calculation unit, 9G...target meter-out flow rate calculation unit, 9H ...Target pump capacity calculation section, 9I...Control valve opening area calculation section, 9J...Regeneration valve opening area calculation section, 9K...Pump control section, 9L...Control valve control section, 9M...Regeneration valve control section, 9N...Distribution control section, 10...Control system, 11...Boom, 12...Arm, 13...Bucket, 21...Boom cylinder, 22...Arm cylinder, 23...Bucket cylinder, 30...Engine, 31...Power transmission mechanism, 32...Hydraulic pump, 33...First flow path, 33A...Supply flow path, 34...Second flow path, 35...Tan , 36...bottom flow path (discharge flow path), 36S...collection section, 37...rod flow path (supply flow path), 37S...collection section, 38...discharge flow path, 39...tank flow path, 40...flow control valve, 41...boom flow control valve, 42...arm flow control valve, 43...bucket flow control valve, 50...bleed valve, 51...throttle, 52...regeneration valve, 53...suction valve, 61...pressure sensor, 62...pressure sensor, 63...pressure sensor, 71...collection flow path (meter-out flow path), 72...collection flow path (meter-in flow path), 100...hydraulic excavator (work machine), AX1...rotating shaft, AX2...rotating shaft, AX3...rotating shaft, P1...first operating position, P2...second operating position, P3...stop position, P4...discharge position, P5...stop position, P6...stop position, P7...regeneration position, Pa...pump port, Pb...bottom port, Pc...rod port, Pd...tank port, Pe...inflow port, Pf...outflow port, Pg...inflow port, Ph...outflow port, Pi...inflow port, Pj...outflow port, RX...swivel shaft.

Claims

1. A plurality of hydraulic pumps that discharge hydraulic oil; A hydraulic cylinder for operating the working machine element; a plurality of flow control valves connected to the plurality of hydraulic pumps, respectively, for adjusting the flow rate of the hydraulic oil supplied to the hydraulic cylinder; A plurality of supply flow paths connected to the plurality of flow control valves, respectively; a meter-in flow passage connecting a collection portion of the plurality of supply flow passages and an inlet of the hydraulic oil of the hydraulic cylinder; A plurality of discharge flow paths connected to the plurality of flow control valves, respectively; a meter-out flow passage connecting a collection portion of the plurality of discharge flow passages and an outlet port of the hydraulic cylinder for the hydraulic oil; A throttle disposed in the meter-out flow path. Work machine control system.

2. The working machine element is raised and lowered by the hydraulic cylinder, The meter-out passage is connected to the outlet through which the hydraulic oil flows out during the lowering operation.

2. A control system for a work machine according to claim 1.

3. The opening area of ​​the throttle is smaller than the maximum opening area of ​​the flow control valve.

3. A control system for a work machine according to claim 2.

4. an operation device that generates an operation command through an operation; A control device, The control device includes: a correlation data storage unit configured to store correlation data between an operation amount of the operating device and a target meter-in flow rate indicating a target flow rate of the hydraulic oil flowing into the inlet; an operation command acquisition unit for acquiring the operation command; a target meter-out flow rate calculation unit that calculates a target meter-out flow rate indicating a target flow rate of the hydraulic oil flowing out from the outlet based on the correlation data and the operation command; a control valve opening area calculation unit that calculates a target opening area of ​​the flow control valve based on the target meter-out flow rate; a control valve control unit that outputs a control command so that the flow control valve becomes the target opening area of ​​the flow control valve, A control system for a work machine according to any one of claims 1 to 3.

5. a regeneration valve for adjusting a regeneration flow rate of the hydraulic oil regenerated from the meter-out passage to the meter-in passage, The control device includes: a target regeneration flow rate calculation unit that calculates a target regeneration flow rate of the hydraulic oil based on the target meter-in flow rate; a regeneration valve opening area calculation unit that calculates a target opening area of ​​the regeneration valve based on the target regeneration flow rate, the pressure of the hydraulic oil flowing into the inlet, and the pressure of the hydraulic oil flowing out from the outlet; A regeneration valve control unit that outputs a control command so that the regeneration valve becomes the target opening area of ​​the regeneration valve. A work machine control system according to claim 4.

6. The work machine element includes a first work machine element and a second work machine element, The hydraulic cylinder includes a first hydraulic cylinder that operates the first work machine element and a second hydraulic cylinder that operates the second work machine element, the flow control valves include a first group of flow control valves consisting of a plurality of flow control valves whose priorities are determined, and a second group of flow control valves consisting of a plurality of flow control valves whose priorities are determined, The first group of flow control valves adjusts the flow rate of the hydraulic oil supplied to the first hydraulic cylinder, The second group of flow control valves adjusts the flow rate of the hydraulic oil supplied to the second hydraulic cylinder, The control device includes: a distribution control unit that controls an opening area of ​​the first group of flow control valves based on a priority of the first group of flow control valves and a required flow rate of the hydraulic oil of the first hydraulic cylinder, A control system for a work machine according to claim 4 or 5.

7. A work machine including a plurality of work machine elements; A plurality of hydraulic cylinders for operating each of the plurality of work machine elements; A work machine control system according to any one of claims 1 to 6. Working machinery.

8. Obtaining an operation command output from an operation device; Calculating a target meter-out flow rate indicating a target flow rate of the hydraulic oil flowing out from an outlet of the hydraulic cylinder based on the operation command and correlation data between an operation amount of the operating device and a target meter-in flow rate indicating a target flow rate of the hydraulic oil flowing into an inlet of the hydraulic cylinder; calculating a target opening area of ​​a flow control valve that adjusts the flow rate of the hydraulic oil supplied to the hydraulic cylinder based on the target meter-out flow rate; and outputting a control command so that the flow control valve has a target opening area of ​​the flow control valve. A method for controlling a work machine.

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