Working machine

Abstract

To provide a working machine which can obtain favorable operability or favorable controllability by accurately controlling the pressure of an actuator without causing an abrupt rise and the hunting of pressure at a start of an operation of the actuator.SOLUTION: A controller 114 calculates target openings of direction control valves 5 to 8, 10, and 11 for reducing a difference between absorption flow rates of actuators 204a, 205a, 206a and 211 and supply flow rates from hydraulic pumps 1, 2 as a valve second target opening a2_TgtVlv, calculates a valve final target opening a_TgtVlv being final target openings of the direction control valves 5 to 8, 10 and 11 on the basis of a valve first target opening a1_TgtVlv and the valve second target opening a2_TgtVlv, and controls the direction control valves 5 to 8, 10 and 11 according to the valve final target opening a_TgtVlv.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a hydraulic control system for performing oil supply and discharge control of a hydraulic actuator provided in a working machine such as a hydraulic excavator.

Background Art

[0002] Generally, various hydraulic actuators are provided in a working machine such as a hydraulic excavator. As a system (hydraulic control system) for performing oil supply and discharge control of such a hydraulic actuator, conventionally, hydraulic oil with a flow rate required by an operation command is discharged from a hydraulic pump, and a direction control valve switches the supply and discharge direction of the hydraulic oil to the hydraulic actuator. The supply flow rate of the hydraulic oil from the hydraulic pump to the hydraulic actuator is controlled by the meter-in opening of the direction control valve, and the discharge flow rate from the hydraulic actuator to the hydraulic oil tank is controlled by the meter-out opening of the direction control valve. Such a configuration is widely known.

[0003] In such a system, for example, even if a sudden signal change is input from an operation lever such as a full lever input, and the hydraulic pump changes the discharge flow rate and the direction control valve suddenly changes the meter-in opening according to the input signal, inertial bodies such as the actuator to be operated and the structures connected thereto cannot follow. Therefore, when the actuator starts to move, a difference occurs between the flow rate supplied from the hydraulic pump to the actuator and the flow rate absorbed by the actuator as it is driven, which leads to a sudden rise in pressure. As a result, shocks due to sudden acceleration of the actuator or pressure surges may occur, which may reduce the operability when the operator manually operates the working machine or the controllability when the actuator operation is controlled by a controller.

[0004] Therefore, conventionally, a bleed-off throttle valve is provided to switch a direction control valve to guide hydraulic oil to an actuator and discharge a part of the discharged oil of a hydraulic pump to a tank, and by adjusting the opening degree of the bleed-off throttle valve when the actuator starts moving, the supply flow rate to the actuator is adjusted and sudden pressure fluctuations are suppressed, thereby ensuring the operability of the work machine (for example, Patent Document 1).

[0005] In addition, a technique is also known in which the discharge pressure (pump pressure) of a hydraulic pump is detected by a pressure sensor and fed back to a controller, and the pump flow rate is controlled according to the increase or decrease of the pump pressure to suppress a sudden pressure increase of the actuator (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, when oil is discharged to a tank by a bleed-off throttle valve as in Patent Document 1, the discharged pressure oil becomes a loss, resulting in a large energy loss. In addition, since the opening characteristics of the bleed-off throttle valve are designed for specific operations, the performance may vary under various operations and operating conditions, which may impair the operability and controllability at the start of movement.

[0008] On the one hand, when measuring pressure and using feedback control as in Patent Document 2, it is possible to maintain a certain pressure controllability even for various operations and operating conditions. However, when calculating the pump flow control command value using the measured pressure at that time, outputting a control command by the controller, and changing the flow rate by the pump, there is always a delay time. It is impossible to correct the pressure fluctuations that occur during this delay time. Therefore, depending on the performance of the feedback control system such as the operating speed of the actuator, the response time of the components, and the calculation performance of the controller, it may not be possible to control the pressure. When the object of pressure feedback control is a hydraulic pump as in Patent Document 2, the actuator pressure cannot be controlled for an actuator driven at a load pressure lower than the pump pressure during combined operation. Therefore, the control object during combined operation can be replaced with a valve, but even in that case, it is impossible to correct the pressure fluctuations that occur during the aforementioned delay time.

[0009] Thus, in a working machine that requires various operations under various conditions, in order to reduce sudden changes in pressure when the actuator starts moving without increasing energy loss, it can be said that it is effective to detect the pressure and control the supplied flow rate. However, since the feedback control system always has a delay, it cannot respond to pressure fluctuations faster than the controllable pressure fluctuations.

[0010] The present invention has been made in view of the above problems, and an object thereof is to provide a working machine that realizes good operability or controllability by accurately controlling the actuator pressure without causing a sudden rise in pressure or hunting when the actuator starts moving.

Means for Solving the Problems

[0011] In order to achieve the above object, the present invention provides a working machine including a vehicle body, a working device attached to the vehicle body, a hydraulic pump, an actuator that drives the vehicle body or the working device, a first direction control valve that controls the flow of pressure oil supplied from the hydraulic pump to the actuator, an operation lever that instructs the operation of the actuator, and a controller that controls the first direction control valve according to the input force of the operation lever. The working machine is provided with an actuator pressure sensor that detects the actuator pressure which is the load pressure of the actuator. The controller calculates an actuator target pressure which is the target pressure of the actuator based on the input force of the operation lever, calculates the target opening of the first direction control valve for reducing the difference between the actuator target pressure and the actuator pressure as the valve first target opening, calculates the target opening of the first direction control valve for reducing the difference between the flow rate absorbed by the actuator during the driving of the actuator and the flow rate supplied from the hydraulic pump to the actuator as the valve second target opening, calculates the valve final target opening which is the final target opening of the first direction control valve based on the valve first target opening and the valve second target opening, and controls the first direction control valve according to the valve final target opening.

[0012] According to the present invention configured as described above, the difference between the actuator target pressure and the actuator pressure is reduced by feedback control, and the difference between the flow rate absorbed by the actuator at the start of movement of the actuator and the supply flow rate from the hydraulic pump is reduced by feedforward control. As a result, the pressure of the actuator can be accurately controlled without causing a sudden pressure rise or hunting at the start of movement of the actuator, so that good operability and controllability can be realized.

Effect of the Invention

[0013] According to the working machine of the present invention, good operability and controllability can be realized by accurately controlling the pressure of the actuator without causing a sudden pressure rise or hunting at the start of movement of the actuator.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2A

Figure 2B

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0015] Hereinafter, a hydraulic excavator will be taken as an example of a working machine according to an embodiment of the present invention, and it will be described with reference to the drawings. In each figure, the same reference numerals are given to equivalent members, and duplicate descriptions will be omitted as appropriate.

[0016] FIG. 1 is a side view of the hydraulic excavator according to the present embodiment. As shown in FIG. 1, the hydraulic excavator 901 includes a traveling body 201, a revolving body 202 that is rotatably disposed on the traveling body 201 and constitutes the vehicle body, and a working device 203 that is rotatably attached to the revolving body 202 in the vertical direction and performs earthwork excavation operations and the like. The revolving body 202 is driven by a swing motor 211 which is an actuator.

[0017] The working device 203 includes a boom 204 rotatably attached to the revolving body 202 in the vertical direction, an arm 205 rotatably attached to the tip of the boom 204 in the vertical direction, a bucket 206 rotatably attached to the tip of the arm 205 in the vertical direction, a boom cylinder 204a which is an actuator for driving the boom 204, an arm cylinder 205a which is an actuator for driving the arm 205, and a bucket cylinder 206a which is an actuator for driving the bucket 206. In the working device 203, inertial measurement devices 212, 213, 214 are installed as operation state sensors for detecting the postures and operation states of the boom 204, the arm 205, and the bucket 206. In the revolving body 202, inertial measurement devices 215, 216 for detecting the posture and rotation speed of the revolving body 202 are installed. Note that the means for acquiring the operation states of the working device 203 and the revolving body 202 are diverse, such as inclination sensors, rotation angle sensors, and stroke sensors, and are not limited to the inertial measurement devices described above.

[0018] A driver's cab 207 is provided at the front position on the revolving body 202, and a counterweight 209 for ensuring the weight balance of the vehicle body is attached at the rear position. A machine room 208 is provided between the driver's cab 207 and the counterweight 209. The machine room 208 houses an engine (not shown), hydraulic pumps 1, 2 (shown in FIG. 2A), a slewing motor 211, a control valve 210, etc. The control valve 210 controls the flow of hydraulic oil from the hydraulic pumps to each actuator.

[0019] FIG. 2A and FIG. 2B are circuit diagrams of a hydraulic drive device mounted on the hydraulic excavator 901.

[0020] (Configuration) The hydraulic drive device 902 includes two main hydraulic pumps (for example, a first hydraulic pump 1 and a second hydraulic pump 2 each consisting of a variable displacement hydraulic pump), a pilot pump 111, and a hydraulic oil tank 3 for supplying oil to the hydraulic pumps 1, 2 and the pilot pump 111. The hydraulic pumps 1, 2 and the pilot pump 111 are driven by an engine (not shown).

[0021] The tilt angle of the first hydraulic pump 1 is controlled by a regulator attached to the first hydraulic pump 1. The regulator of the first hydraulic pump 1 has a flow control command pressure port 1a and is driven by a command pressure acting on the flow control command pressure port 1a. The tilt angle of the second hydraulic pump 2 is controlled by a regulator attached to the second hydraulic pump 2. The regulator of the second hydraulic pump 2 has a flow control command pressure port 2a and is driven by a command pressure acting on the flow control command pressure port 2a.

[0022] A travel right direction control valve 4, an arm second direction control valve 5, a boom first direction control valve 6, and a bucket direction control valve 7 are respectively connected in parallel to a pump flow path 40 of the first hydraulic pump 1 via meter-in flow paths 41, 42, meter-in flow paths 43, 44, meter-in flow paths 45, 46, and meter-in flow paths 47, 48. Check valves 13 to 16 are respectively arranged in the meter-in flow paths 41, 42, meter-in flow paths 43, 44, meter-in flow paths 45, 46, and meter-in flow paths 47, 48 to prevent the reverse flow of pressure oil into the pump flow path 40.

[0023] The travel right direction control valve 4 controls the flow of pressure oil supplied from the first hydraulic pump 1 to a travel right motor (not shown) among a pair of travel motors that drive the traveling body 201. The arm second direction control valve 5 controls the flow of pressure oil supplied from the first hydraulic pump 1 to the arm cylinder 205a. The boom first direction control valve 6 controls the flow of pressure oil supplied from the first hydraulic pump 1 to the boom cylinder 204a. The bucket direction control valve 7 controls the flow of pressure oil supplied from the first hydraulic pump 1 to the bucket cylinder 206a.

[0024] The pump flow path 40 is connected to the hydraulic oil tank 3 via a check valve 26 and a relief valve 25 to protect the circuit from excessive pressure rise. The pump flow path 40 is connected to the hydraulic oil tank 3 via a bleed-off valve 23 to discharge the excess discharge oil of the first hydraulic pump 1.

[0025] In the pump passage 50 of the second hydraulic pump 2, a swing direction control valve 8, a traveling left direction control valve 9, an arm first direction control valve 10, a boom second direction control valve 11, and a spare direction control valve 12 are respectively connected in parallel via meter-in passages 51, 52, meter-in passages 53, 54, meter-in passages 55, 56, meter-in passages 57, 58, and meter-in passages 59, 60. Check valves 17 to 21 are respectively arranged in the meter-in passages 51, 52, meter-in passages 53, 54, meter-in passages 55, 56, meter-in passages 57, 58, and meter-in passages 59, 60 to prevent the backflow of the pressure oil to the pump passage 50.

[0026] The swing direction control valve 8 controls the flow of the pressure oil supplied from the second hydraulic pump 2 to the swing motor 211. The traveling left direction control valve 9 controls the flow of the pressure oil supplied from the second hydraulic pump 2 to a traveling left motor (not shown) among a pair of traveling motors that drive the traveling body 201. The arm first direction control valve 10 controls the flow of the pressure oil supplied from the second hydraulic pump 2 to the arm cylinder 205a. The boom second direction control valve 11 controls the flow of the pressure oil supplied from the second hydraulic pump 2 to the boom cylinder 204a. The spare direction control valve 12 controls the flow of the pressure oil supplied from the second hydraulic pump 2 to an actuator (not shown) that drives a special attachment such as a small harvester provided in place of the bucket 206, for example.

[0027] The pump passage 50 is connected to the hydraulic oil tank 3 via a bleed-off valve 24 to discharge the surplus discharge oil of the second hydraulic pump 2. The pump passage 50 is connected to the hydraulic oil tank 3 via a check valve 27 and a relief valve 25 to protect the circuit from excessive pressure rise. The pump passage 50 is connected to the pump passage 40 via a confluence valve 22 to confluence the discharge oil of the first hydraulic pump 1.

[0028] A pressure sensor 91 for detecting the discharge pressure (pump pressure) of the first hydraulic pump 1 is provided in the pump passage 40. A pressure sensor 92 for detecting the discharge pressure (pump pressure) of the second hydraulic pump 2 is provided in the pump passage 50. A pressure sensor 95 for detecting the actuator pressure on the bottom side of the boom cylinder 204a is provided in a passage 63 connecting the port Bm2B of the boom second direction control valve 11 and the boom cylinder 204a and in a passage 64 connecting the port Bm1B of the boom first direction control valve 11 and the boom cylinder 204a. A pressure sensor 96 for detecting the actuator pressure on the rod side of the boom cylinder 204a is provided in a passage 65 connecting the port Bm2R of the boom second direction control valve 11 and the boom cylinder 204a and in a passage 66 connecting the port Bm1R of the boom first direction control valve 11 and the boom cylinder 204a. A pressure sensor 97 for detecting the actuator pressure on the bottom side of the arm cylinder 205a is provided in a passage 67 connecting the port Am2B of the arm second direction control valve 5 and the arm cylinder 205a and in a passage 68 connecting the port Am1B of the arm first direction control valve 10 and the arm cylinder 205a. A pressure sensor 98 for detecting the actuator pressure on the rod side of the arm cylinder 205a is provided in a passage 69 connecting the port Am2R of the arm second direction control valve 5 and the arm cylinder 205a and in a passage 70 connecting the port Am1R of the arm first direction control valve 10 and the arm cylinder 205a. A pressure sensor 99 for detecting the actuator pressure on the bottom side of the bucket cylinder 206a is provided in a passage 71 connecting the port BkB of the bucket direction control valve 7 and the arm cylinder 205a. A pressure sensor 100 for detecting the actuator pressure on the rod side of the bucket cylinder 206a is provided in a passage 72 connecting the port BkR of the bucket direction control valve 7 and the arm cylinder 205a. A pressure sensor 93 for detecting the actuator pressure of one side of the swing motor 211 is provided in a passage 73 connecting the port SwgR of the swing direction control valve 8 and the swing motor 211. A pressure sensor 94 for detecting the actuator pressure of the other side of the swing motor 211 is provided in a passage 74 connecting the port SwgL of the swing direction control valve 8 and the swing motor 211.For simplicity of explanation, the pressure sensors for detecting the actuator pressures of the right traveling motor, left traveling motor, and the actuator for driving the special attachment, which are not shown in the drawings, are omitted from the illustration.

[0029] In FIG. 2B, the discharge port of the pilot pump 111 is connected to the hydraulic oil tank 3 via the pilot relief valve 112 for generating the pilot primary pressure, and is also connected to one input port of the solenoid valves 113a to 113j built in the solenoid valve unit 113 via the flow path 116 that supplies the discharge pressure discharged from the pilot pump 111. The other input ports of the solenoid valves 113a to 113j are connected to the hydraulic oil tank 3 via the flow path 117 that guides the return oil from the solenoid valves 113a to 113j. The solenoid valves 113a to 113j each reduce the pilot primary pressure according to the command signal from the controller 114 and output it as the command pressure.

[0030] The output port of the solenoid valve 113a is connected to the flow rate control command pressure port 1a of the regulator of the first hydraulic pump 1. The output port of the solenoid valve 113b is connected to the flow rate control command pressure port 2a of the regulator of the second hydraulic pump 2. The output ports of the solenoid valves 113c and 113d are connected to the command pressure ports 6a and 6b of the boom first direction control valve 6. The output ports of the solenoid valves 113e and 113f are connected to the command pressure ports 8a and 8b of the swing direction control valve 8. The output ports of the solenoid valves 113g and 113h are connected to the command pressure ports 11a and 11b of the boom second direction control valve 11. The output port of the solenoid valve 113i is connected to the command pressure port 23a of the bleed-off valve 23. The output port of the solenoid valve 113j is connected to the command pressure port 24a of the bleed-off valve 24. For simplicity of explanation, the solenoid valves for the right traveling direction control valve 6, the solenoid valves for the arm second direction control valve 5, the solenoid valves for the bucket direction control valve 7, the solenoid valves for the left traveling direction control valve 9, the solenoid valves for the arm first direction control valve 10, and the solenoid valves for the spare direction control valve 12 are omitted from the illustration.

[0031] Current meters 131 to 140 for measuring command current (solenoid current) are provided in the signal lines connecting the controller 114 and the solenoid valves 113a to 113j. The controller 114 can calculate the tilting amount of the hydraulic pumps 1 and 2 based on the solenoid current of the solenoid valves 113a and 113b, calculate the opening amount of the direction control valves 6, 8, and 11 based on the solenoid current of the solenoid valves 113c to 113h, and calculate the opening amount of the bleed-off valves 23 and 24 based on the solenoid current of the solenoid valves 113i and 113j.

[0032] The hydraulic drive device 902 includes a boom operation lever 115a that can switch the boom first direction control valve 6 and the boom second direction control valve 11, and an arm operation lever 115b that can switch the arm first direction control valve 10 and the arm second direction control valve 5. For the sake of simplicity of explanation, the illustration of the travel right operation lever for switching the travel right direction control valve 4, the bucket operation lever for switching the bucket direction control valve 7, the swing operation lever for switching the swing direction control valve 8, the travel left operation lever for switching the travel left direction control valve 9, and the spare operation lever for switching the spare direction control valve 12 is omitted.

[0033] The hydraulic drive device 902 includes a controller 114. The controller 114 outputs a command signal to the solenoid valves 113a to 113j (including solenoid valves not shown) of the solenoid valve unit 113 according to the input amount of the operation levers 115a and 115b, the output values of the inertial measurement devices 212 to 216, and the output values of the pressure sensors 91 to 100.

[0034] FIG. 3 is a functional block diagram of the controller 114. In FIG. 3, the controller 114 includes an actuator required speed calculation unit 114a, an actuator target pressure calculation unit 114b, a first valve target opening calculation unit 114c, a first valve estimated flow rate calculation unit 114d, a confluence ratio calculation unit 114e, an actuator estimated speed calculation unit 114f, an actuator estimated flow rate calculation unit 114g, a second valve estimated flow rate calculation unit 114h, a valve required flow rate calculation unit 114i, a final valve estimated flow rate calculation unit 114j, a second valve target opening calculation unit 114k, a final valve target opening calculation unit 114l, a direction control valve control command output unit 114m, a pump target pressure calculation unit 114n, a pump target flow rate calculation unit 114o, a pump flow rate control command output unit 114p, a bleed-off valve target opening calculation unit 114q, and a bleed-off valve control command output unit 114r.

[0035] The actuator required speed calculation unit 114a calculates an actuator required speed V_ReqAct according to an actuator required speed characteristic with respect to a preset operation lever input amount, in accordance with the operation lever input amount. The actuator target pressure calculation unit 114b calculates an actuator pressure for achieving the actuator required speed V_ReqAct calculated by the actuator required speed calculation unit 114a as an actuator target pressure P_TgtAct. The first valve target opening calculation unit 114c calculates a target opening of the direction control valves 5 to 8, 10, 11 for reducing the difference between the actuator target pressure P_TgtAct calculated by the actuator target pressure calculation unit 114b and the actuator pressure P_Act acquired by the pressure sensor as a first valve target opening a1_TgtVlv.

[0036] The valve first estimated flow rate calculation unit 114d calculates the first estimated valve flow rate based on the pump pressure P_Pmp and the actuator pressure P_Act acquired by the pressure sensor, and the openings of the direction control valves 5 to 8, 10, and 11 estimated from the solenoid current of the solenoid valve acquired by the ammeter. The confluence ratio calculation unit 114e calculates the confluence ratio R_Cnf of each direction control valve based on the first estimated valve flow rate calculated by the valve first estimated flow rate calculation unit 114d. The confluence ratio is the ratio of the flow rate of each direction control valve to the total flow rate of all the direction control valves that supply pressure oil to the same actuator.

[0037] The actuator estimated speed calculation unit 114f calculates the actuator estimated speed based on the actuator operating state information acquired from an inertial measurement device or the like. The actuator estimated flow rate calculation unit 114g calculates the actuator estimated flow rate Q_EstAct based on the actuator estimated speed calculated by the actuator estimated speed calculation unit 114f and the design specifications of the actuator.

[0038] The valve second estimated flow rate calculation unit 114h calculates the second estimated valve flow rate Q2_EstVlv based on the actuator estimated flow rate Q_EstAct calculated by the actuator estimated flow rate calculation unit 114g and the confluence ratio R_Cnf calculated by the confluence ratio calculation unit 114e. The valve required flow rate calculation unit 114i calculates the valve required flow rate Q_ReqVlv based on the actuator required speed V_ReqAct calculated by the actuator required speed calculation unit 114a. The valve final estimated flow rate calculation unit 114j calculates the final valve estimated flow rate (valve final estimated flow rate) based on the first estimated valve flow rate calculated by the valve first estimated flow rate calculation unit 114d, the second estimated valve flow rate Q2_EstVlv calculated by the valve second estimated flow rate calculation unit 114h, and the valve required flow rate Q_ReqVlv calculated by the valve required flow rate calculation unit 114i.

[0039] The valve second target opening calculation unit 114k calculates the target opening of the directional control valves 5 to 8, 10, 11 for reducing the difference between the absorption flow rate of the actuator and the supply flow rate from the hydraulic pump, namely the valve second target opening a2_TgtVlv, based on the actuator target pressure P_TgtAct calculated by the actuator target pressure calculation unit 114b, the pump pressure P_Pmp acquired from the pressure sensor, and the valve final estimated flow rate calculated by the valve final estimated flow rate calculation unit 114j. Here, the suction flow rate of the actuator is the flow rate absorbed by the actuator as it is driven. For example, in the case of a hydraulic cylinder, it is obtained by multiplying the pressure receiving area of the piston by the moving speed of the piston.

[0040] The valve final target opening calculation unit 114l calculates the final target opening of the directional control valve, namely the valve final target opening a_TgtVlv, based on the valve first target opening a1_TgtVlv calculated by the valve first target opening calculation unit 114c and the valve second target opening a2_TgtVlv calculated by the valve second target opening calculation unit 114k. The directional control valve control command output unit 114m outputs a command signal (directional control valve control command signal) corresponding to the valve final target opening a_TgtVlv calculated by the valve final target opening calculation unit 114l to the solenoid valve for the directional control valve according to the solenoid valve command signal characteristics for the preset directional control valve target opening.

[0041] The pump target pressure calculation unit 114n calculates the pump target pressure P_TgtPmp based on the actuator target pressure P_TgtAct calculated by the actuator target pressure calculation unit 114b. The pump target flow rate calculation unit 114o calculates the pump target flow rate Q_TgtPmp based on the pump target pressure P_TgtPmp calculated by the pump target pressure calculation unit 114n and the pump pressure P_Pmp obtained from the pressure sensor. The pump flow rate control command output unit 114p outputs a command signal (pump flow rate control command signal) corresponding to the pump target flow rate Q_TgtPmp calculated by the pump target flow rate calculation unit 114o to the solenoid valve for pump flow rate control according to the solenoid valve command signal characteristics for the preset pump target flow rate Q_TgtPmp.

[0042] The bleed-off valve target opening calculation unit 114q calculates a bleed-off valve target opening according to the operation lever input amount, in accordance with the bleed-off valve target opening characteristic for a preset operation lever input amount. The bleed-off valve control command output unit 114r outputs a command signal (bleed-off valve control command signal) corresponding to the bleed-off valve target opening to the electromagnetic valve for the bleed-off valve, in accordance with the electromagnetic valve command signal characteristic for a preset bleed-off valve target opening.

[0043] Figure 4 is a flowchart showing the processing of the controller 114 related to pump flow control.

[0044] The controller 114 first determines whether there is an operation lever input (step S101). If it is determined in step S101 that there is no operation lever input (YES), the flow is terminated.

[0045] If it is determined in step S101 that there is an operation lever input (NO), the actuator required speed calculation unit 114a calculates an actuator required speed V_ReqAct according to the operation lever input amount, in accordance with the actuator speed characteristic for a preset operation lever input amount (step S102).

[0046] Following step S102, the actuator target pressure calculation unit 114b calculates an actuator target pressure P_TgtAct for achieving the actuator required speed V_ReqAct (step S103).

[0047] Following step S103, the pump target pressure calculation unit 114n calculates a pump target pressure P_TgtPmp based on the actuator target pressure P_TgtAct (step S104). The pump target pressure P_TgtPmp is set to the same value as the maximum load pressure or a pressure higher than the maximum load pressure, for example, among the actuators supplied with the hydraulic oil discharged by the hydraulic pump.

[0048] Following step S104, the pump target flow rate calculation unit 114o calculates the pump target flow rate Q_TgtPmp based on the pump target pressure P_TgtPmp and the pump pressure P_Pmp (step S105). The pump target flow rate Q_TgtPmp is calculated, for example, using a PID control method or the like so that the difference between the pump target pressure P_TgtPmp and the pump pressure P_Pmp becomes small.

[0049] Following step S105, the pump flow rate control command output unit 114p outputs a command signal (pump flow rate control command signal) corresponding to the pump target flow rate Q_TgtPmp to the solenoid valves 113a and 113b for pump flow rate control according to the solenoid valve command signal characteristics for the preset pump target flow rate Q_TgtPmp (step S106), and ends the flow.

[0050] FIG. 5 is a flowchart showing the processing of the controller 114 related to the opening control of the direction control valve.

[0051] The controller 114 first determines whether there is no operation lever input (step S201). If it is determined in step S201 that there is no operation lever input (YES), the flow is ended.

[0052] If it is determined in step S201 that there is an operation lever input (NO), the actuator required speed calculation unit 114a calculates the actuator required speed V_ReqAct corresponding to the operation lever input amount according to the actuator speed characteristics for the preset operation lever input amount (step S202).

[0053] Following step S202, the actuator target pressure calculation unit 114b calculates the actuator target pressure P_TgtAct for achieving the actuator required speed V_ReqAct (step S203).

[0054] Following step S204, the first valve target opening calculation unit 114c calculates the first valve target opening a1_TgtVlv based on the actuator target pressure P_TgtAct and the actuator pressure P_Act obtained from the pressure sensor (step S204). Note that the first valve target opening a1_TgtVlv is calculated, for example, using a PID control method or the like so that the difference between the actuator target pressure P_TgtAct and the actuator pressure P_Act becomes small.

[0055] In parallel with step S204, the first valve estimated flow rate calculation unit 114d calculates the first valve estimated flow rate Q1_EstVlv based on the pump pressure P_Pmp and the actuator pressure P_Act obtained from the output value of the pressure sensor and the direction control valve opening amount a_EstVlv estimated from the solenoid current Am_Sol of the solenoid valve obtained from the ammeter (step S205). The first valve estimated flow rate Q1_EstVlv is calculated, for example, from Equation 1.

[0056]

Equation

[0057] Here, Cd is the flow coefficient and ρ is the working oil density.

[0058] Following step S205, the confluence ratio calculation unit 114e calculates the confluence ratio R_Cnf of the direction control valve from Equation 2 using the first valve estimated flow rate Q1_EstVlv (step S206).

[0059]

Equation

[0060] Here, Q1_EstVlvSum is the sum of the first valve estimated flow rates Q1_EstVlv of all the direction control valves that supply pressure oil to the same actuator.

[0061] Following step S206, the actuator estimated speed calculation unit 114f calculates an actuator estimated speed V_EstAct based on actuator operation state information obtained from the inertial measurement units 212 to 216 or the like (step S207).

[0062] Following step S207, the actuator estimated flow rate calculation unit 114g calculates an actuator estimated flow rate Q_EstAct based on the actuator estimated speed V_EstAct and the design specifications of the actuator (step S208).

[0063] Following step S208, the second valve estimated flow rate calculation unit 114h calculates a second valve estimated flow rate Q2_EstVlv from Equation 3 using the actuator estimated flow rate Q_EstAct and the confluence ratio R_Cnf (step S209).

[0064]

Equation

[0065] Following step S210, the valve required flow rate calculation unit 114i calculates a valve required flow rate Q_ReqVlv based on the actuator required speed V_ReqAct and the design specifications of the actuator (step S210).

[0066] Following step S210, the final valve estimated flow rate calculation unit 114j calculates a final valve estimated flow rate Q_EstVlv from Equation 4 using the first valve estimated flow rate Q1_EstVlv, the second valve estimated flow rate Q2_EstVlv, and the valve required flow rate Q_ReqVlv (step S211).

[0067]

Equation

[0068] Here, α is obtained from Equation 5, and β is obtained from Equation 6.

[0069]

Equation

[0070]

Number

[0071] Here, the final estimated valve flow rate Q_EstVlv is the weighted average of the first estimated valve flow rate Q1_EstVlv and the second estimated valve flow rate Q2_EstVlv. The weight coefficient of the first estimated valve flow rate Q1_EstVlv is α×β, but the weight coefficient of the first estimated valve flow rate Q1_EstVlv may also be α. The final estimated valve flow rate Q_EstVlv in that case is expressed by Equation 7.

[0072]

Number

[0073] Following step S211, the second target valve opening calculation unit 114k calculates the second target valve opening a2_TgtVlv that reduces the difference between the absorption flow rate of the actuator and the supply flow rate from the hydraulic pump from Equation 8 using the final estimated valve flow rate Q_EstVlv, the target actuator pressure P_TgtAct, and the pump pressure P_Pmp (step S212).

[0074]

Number

[0075] Following steps S204 and S212, the final target valve opening calculation unit 114l calculates the final target valve opening a_TgtVlv from Equation 9 using the first target valve opening a1_TgtVlv and the second target valve opening a2_TgtVlv (step S213).

[0076]

Number

[0077] Subsequent to step S213, the direction control valve control command output unit 114m outputs a command signal (direction control valve control command signal) corresponding to the valve final target opening a_TgtVlv to the electromagnetic valve for the direction control valve in accordance with the electromagnetic valve command signal characteristics with respect to the preset valve final target opening a_TgtVlv (step S214), and ends the flow.

[0078] FIG. 6 is a flowchart showing the processing of the controller 114 related to the opening control of the bleed-off valves 23 and 24. Hereinafter, only the processing related to the opening control of the bleed-off valve 23 for the first hydraulic pump 1 will be described. Since the processing related to the opening control of the bleed-off valve 24 for the second hydraulic pump 2 is the same as this, the description thereof will be omitted.

[0079] The controller 114 first determines whether there is no operation lever input (step S301). If it is determined in step S301 that there is no operation lever input (YES), the flow is ended.

[0080] If it is determined in step S301 that there is an operation lever input (NO), the bleed-off valve target opening calculation unit 114q calculates a bleed-off valve target opening a_TgtBO corresponding to the operation lever input amount in accordance with the bleed-off valve opening characteristics with respect to the preset operation lever input amount (step S302).

[0081] Subsequent to step S302, the bleed-off valve control command output unit 114r outputs a command signal (bleed-off valve control command signal) corresponding to the bleed-off valve target opening a_TgtBO to the electromagnetic valve for the bleed-off valve in accordance with the electromagnetic valve command signal characteristics with respect to the preset bleed-off valve opening amount (step S303), and ends the flow.

[0082] (Operation) As an example of the operation of the hydraulic drive device 902, the operation when a single operation of driving only the swing motor 211 or the boom cylinder 204a is performed will be described.

[0083] FIG. 7 is a diagram showing the time-series changes in the operation lever input amount, actuator target pressure, actuator pressure, and actuator speed when a single operation is performed. Note that the actuator pressure and actuator speed when only pressure feedback control is performed are shown as comparative examples.

[0084] When the operator operates the swivel operation lever, the controller 114 calculates the actuator target pressure based on the operation lever input amount. Based on this actuator target pressure, the pump target flow rate Q_TgtPmp and the final target opening a_TgtVlv of the valve are calculated, and a command signal is output to the electromagnetic valve for pump flow control and the electromagnetic valve for the direction control valve. The electromagnetic valve generates a pilot pressure corresponding to the command signal, and upon receiving this pilot pressure, the pump adjusts the flow rate by changing the pump tilt, and the direction control valve adjusts the opening amount so as to reach the actuator target pressure. At this time, the difference between the actuator target pressure and the actuator pressure is caused by two factors.

[0085] The first factor is the difference P_Error1 between the actuator target pressure and the actuator pressure, which is expressed by Equation 10.

[0086]

Equation

[0087] The second factor is the pressure change amount P_Error2 caused by the deviation between the absorption flow rate of the actuator and the supply flow rate from the hydraulic pump, which is expressed by Equation 11.

[0088]

Equation

[0089] Here, K is the bulk modulus of elasticity, and V is the volume.

[0090] For these two pressure error factors, the controller 114 calculates the first target valve opening a1_TgtVlv for reducing P_Error1 and calculates the second target valve opening a2_TgtVlv for reducing P_Error2. As a result, since the actuator supply flow rate is adjusted so that both P_Error1 and P_Error2 are reduced, the actuator pressure can be controlled to the actuator target pressure. Consequently, the actuator accelerates well without causing shock or hunting.

[0091] On the other hand, when only pressure feedback control is performed, P_Error1 can be reduced, but P_Error2 cannot be reduced. Therefore, it is impossible to suppress the pressure change caused by the difference between the supply flow rate to the actuator and the absorption flow rate of the actuator that occurs during the delay time of the pressure feedback control. For example, when the absorption flow rate of the actuator is larger than the supply flow rate to the actuator, there is a shortage of flow rate, and the actuator pressure does not reach the actuator target pressure as shown in FIG. 7. Further, when the feedback gain is increased in an attempt to reduce P_Error2 by pressure feedback control, hunting as shown in FIG. 7 may occur.

[0092] Also, when the boom operation lever is operated, the boom cylinder 204a may be driven by combining the flow rates passing through the first boom direction control valve 6 and the second boom direction control valve 11. In this case, the controller 114 calculates the confluence ratio R_Cnf, and after grasping how much the flow rates of the direction control valves 6 and 11 contribute to the absorption flow rate of the boom cylinder 204a, calculates the second target valve opening for reducing P_Error2. As a result, it is possible to prevent the flow rate adjustment amount of one direction control valve from being offset by the other direction control valve, so that the boom cylinder 204a accelerates well without causing shock or hunting.

[0093] FIG. 8 is a diagram showing the time-series changes in the operation lever input amount, valve required flow rate Q_ReqVlv, valve first estimated flow rate Q1_EstVlv, valve second estimated flow rate Q2_EstVlv, and valve final estimated flow rate Q_EstVlv when a single operation is performed.

[0094] At time T1, when the operation lever is operated, the valve required flow rate Q_ReqVlv corresponding to the operation lever input amount is calculated, and a command signal corresponding to the valve required flow rate Q_ReqVlv is output to the hydraulic pumps 1, 2 and the direction control valve.

[0095] At time T2, when the direction control valve opens and hydraulic oil is supplied to the actuator, the valve first estimated flow rate Q1_EstVlv is calculated using the differential pressure across the direction control valve detected by the pressure sensor and the solenoid current of the solenoid valve detected by the ammeter. At this time, since the movement state sensors 212 to 216 cannot detect the movement due to the inertial delay of the vehicle body 202 or the working device 203, the valve second estimated flow rate Q2_EstVlv becomes zero. Therefore, the valve final estimated flow rate Q_EstVlv coincides with the valve first estimated flow rate Q1_EstVlv.

[0096] At time T3, movement is detected by the movement state sensors 212 to 216, and the valve second estimated flow rate Q2_EstVlv increases. At this time, since both the valve first estimated flow rate Q1_EstVlv and the valve second estimated flow rate Q2_EstVlv become positive values, according to Equation 4, as the difference between the valve second estimated flow rate Q2_EstVlv and the valve first estimated flow rate Q1_EstVlv becomes smaller, the valve final estimated flow rate Q_EstVlv is calculated so that the ratio of the valve second estimated flow rate Q2_EstVlv becomes larger.

[0097] At time T4, according to Equation 4, as the difference between the valve second estimated flow rate Q2_EstVlv and the valve required flow rate Q_ReqVlv becomes smaller, the ratio of the valve first estimated flow rate Q1_EstVlv becomes smaller, and finally the valve final estimated flow rate Q_EstVlv substantially coincides with the valve second estimated flow rate Q2_EstVlv.

[0098] Here, the relationship between the second estimated valve flow rate Q2_EstVlv and the first estimated valve flow rate Q1_EstVlv will be described. Since the second estimated valve flow rate calculation unit 114h calculates the second estimated valve flow rate Q2_EstVlv based on the information acquired by the operation state sensors 212 to 216, the valve flow rate can be estimated with high accuracy after the actuator starts to move. However, since the flow rate cannot be estimated unless after the actuator starts to move, the flow rate cannot be accurately estimated under conditions where the influence of the inertial delay of the actuator, such as at the start, is large. On the other hand, since the first estimated valve flow rate calculation unit 114d calculates the first estimated valve flow rate Q1_EstVlv based on the flow rate supplied to the actuator, the valve flow rate can be estimated without being affected by the inertial delay of the actuator. However, since it is the flow rate estimated from the pressure, solenoid current, etc., the estimation error is larger compared to the second estimated valve flow rate Q2_EstVlv.

[0099] Therefore, in a state where the influence of the inertial delay at the start of the actuator is large, the actuator supply flow rate is estimated and controlled based on the opening of the direction control valve and the differential pressure before and after. In a state where the actuator speed can be measured with high accuracy by the operation state sensors 212 to 216, the actuator supply flow rate is estimated with higher accuracy based on the output values from the operation state sensors 212 to 216 and controlled, so that good actuator control accuracy can be achieved in any operation state.

[0100] (Summary) In this embodiment, in a working machine 901 including a vehicle body 202, a working device attached to the vehicle body 202, hydraulic pumps 1 and 2, actuators 204a, 205a, 206a, 211 that drive the vehicle body 202 or the working device 203, first direction control valves 5 to 8, 10, 11 that control the flow of pressure oil supplied from the hydraulic pumps 1 and 2 to the actuators 204a, 205a, 206a, 211, operation levers 115a, 115b that instruct the operation of the actuators 204a, 205a, 206a, 211, and a controller 114 that controls the first direction control valves 5 to 8, 10, 11 according to the input force amount of the operation levers 115a, 115b, actuator pressure sensors 93 to 100 that detect the actuator pressure P_Act which is the load pressure of the actuators 204a, 205a, 206a, 211 are provided. The controller 114 calculates an actuator target pressure P_TgtAct which is the target pressure of the actuators 204a, 205a, 206a, 211 based on the input force amount of the operation levers 115a, 115b, calculates the target opening of the first direction control valves 5 to 8, 10, 11 for reducing the difference between the actuator target pressure P_TgtAct and the actuator pressure P_Act as a valve first target opening a1_TgtVlv, calculates the target opening of the first direction control valves 5 to 8, 10, 11 for reducing the difference between the flow rate absorbed by the actuators 204a, 205a, 206a, 211 and the flow rate supplied from the hydraulic pumps 1 and 2 to the actuators 204a, 205a, 206a, 211 as a valve second target opening a2_TgtVlv, calculates a valve final target opening a_TgtVlv which is the final target opening of the first direction control valves 5 to 8, 10, 11 based on the valve first target opening a1_TgtVlv and the valve second target opening a2_TgtVlv, and controls the first direction control valves 5 to 8, 10, 11 according to the valve final target opening a_TgtVlv.

[0101] According to the present embodiment configured as described above, the difference between the actuator target pressure P_TgtAct and the actuator pressure P_Act is reduced by feedback control, and the difference between the absorption flow rate of the actuator at the start of movement of the actuators 204a, 205a, 206a, 211 and the supply flow rate from the hydraulic pumps 1, 2 is reduced by feedforward control. As a result, the pressure of the actuators 204a, 205a, 206a, 211 can be accurately controlled without causing a sudden pressure rise or hunting when the actuators 204a, 205a, 206a, 211 start to move, so that good operability and controllability can be realized.

[0102] Further, the working machine 901 in the present embodiment includes pump pressure sensors 91, 92 that detect the pump pressure P_Pmp which is the discharge pressure of the hydraulic pumps 1, 2, and operation state sensors 212 to 216 that measure the postures and operation speeds of the vehicle body 202 and the working device 203. The controller 114 calculates a valve first estimated flow rate Q1_EstVlv which is a provisional estimated value of the flow rates of the first direction control valves 5 to 8, 10, 11 based on the information obtained from the actuator pressure sensors 93 to 100 and the pump pressure sensors 91, 92, and calculates a valve second estimated flow rate Q2_EstVlv which is a provisional estimated value of the flow rates of the first direction control valves 5 to 8, 10, 11 based on the information obtained by the operation state sensors 212 to 216. Based on the valve first estimated flow rate Q1_EstVlv and the valve second estimated flow rate Q2_EstVlv, the controller 114 calculates a valve final estimated flow rate Q_EstVlv which is the final estimated value of the flow rates of the first direction control valves 5 to 8, 10, 11, and calculates a valve second target opening a2_TgtVlv based on the valve final estimated flow rate Q_EstVlv, the pump pressure P_Pmp, and the actuator target pressure P_TgtAct. Thereby, it becomes possible to calculate the valve second target opening a2_TgtVlv based on the pump pressure P_Pmp and the operation states of the actuators 204a, 205a, 206a, 211.

[0103] In addition, the working machine 901 in the present embodiment includes a plurality of direction control valves 5-8, 10, 11 including first direction control valves 5-8, 10, 11 that control the flow of pressure oil supplied from hydraulic pumps 1 and 2 to actuators 204a, 205a, 206a, 211. The controller 114 calculates an estimated actuator flow rate Q_EstAct, which is an estimated value of the flow rate supplied to the actuators 204a, 205a, 206a, 211, based on the information acquired by the operating state sensors 212-216, calculates the ratio of the valve first estimated flow rate Q1_EstVlv of the first direction control valves 5-8, 10, 11 to the total Q1_EstVlvSum of the valve first estimated flow rates Q1_EstVlv of the plurality of direction control valves 5-8, 10, 11 as the confluence ratio R_Cnf, and calculates a value obtained by multiplying the actuator estimated flow rate Q_EstAct by the confluence ratio R_Cnf as the valve second estimated flow rate Q2_EstVlv. As a result, it becomes possible to calculate the valve second estimated flow rate Q2_EstVlv for each of the plurality of direction control valves that supply pressure oil to the same actuator.

[0104] Further, the controller 114 in the present embodiment calculates a weighted average of the valve first estimated flow rate Q1_EstVlv and the valve second estimated flow rate Q2_EstVlv as the valve final estimated flow rate Q_EstVlv, where the deviation rate α of the valve second estimated flow rate Q2_EstVlv with respect to the valve first estimated flow rate Q1_EstVlv is used as the weight coefficient of the valve first estimated flow rate Q1_EstVlv, and a value obtained by subtracting the deviation rate α from 1 is used as the weight coefficient of the valve second estimated flow rate Q2_EstVlv. As a result, the valve final estimated flow rate Q_EstVlv coincides with the valve first estimated flow rate Q1_EstVlv when the actuator starts to move, and approaches the valve second estimated flow rate Q2_EstVlv after the actuator starts to move. As a result, it becomes possible to estimate the valve flow rate with high accuracy both when the actuator starts to move and after it starts to move.

[0105] Also, the controller 114 in the present embodiment calculates an actuator required speed V_ReqAct, which is the operating speed required for the actuators 204a, 205a, 206a, 211, based on the input amounts of the operation levers 115a and 115b. Based on the actuator required speed V_ReqAct, the controller 114 calculates the flow rate required for the first-direction control valves 5 to 8, 10, and 11 as a valve required flow rate Q_ReqVlv, and calculates the product α×β of the deviation rate α of the valve second estimated flow rate Q2_EstVlv from the valve first estimated flow rate Q1_EstVlv and the deviation rate β of the valve second estimated flow rate from the valve required flow rate Q_ReqVlv as a weight coefficient of the valve first estimated flow rate Q1_EstVlv, and calculates the weighted average of the valve first estimated flow rate Q1_EstVlv and the valve second estimated flow rate Q2_EstVlv as a valve final estimated flow rate Q_EstVlv, where the value obtained by subtracting the product α×β from 1 is used as the weight coefficient of the valve second estimated flow rate Q2_EstVlv. Thereby, even when there is a difference (the deviation rate α is large) between the valve estimated flow rate (valve first estimated flow rate Q1_EstVlv) based on the valve opening amount and the estimated flow rate (valve second estimated flow rate Q2_EstVlv) based on the actuator speed, as the estimated flow rate (valve second estimated flow rate Q2_EstVlv) based on the actuator speed approaches the valve required flow rate Q_ReqVlv based on the actuator required speed V_ReqAct (the deviation rate β becomes small), the valve final estimated flow rate Q_EstVlv approaches the valve second estimated flow rate Q2_EstVlv. As a result, regardless of the valve individual differences, it becomes possible to estimate the valve flow rate with high accuracy both when the actuators 204a, 205a, 206a, 211 start moving and after they start moving.

[0106] As described above, the embodiments of the present invention have been described in detail, but the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention and are not necessarily limited to those having all the configurations described.

Explanation of Reference Numerals

[0107] 1…First hydraulic pump, 1a…Flow control command pressure port, 2…Second hydraulic pump, 2a…Flow control command pressure port, 3…Hydraulic oil tank, 4…Travel right direction control valve, 5…Arm second direction control valve, 6…Boom first direction control valve, 6a, 6b…Command pressure ports, 7…Bucket direction control valve, 8…Swing direction control valve, 8a, 8b…Command pressure ports, 9…Travel left direction control valve, 10…Arm first direction control valve, 11…Boom second direction control valve, 11a, 11b…Command pressure ports, 12…Standby direction control valve, 13 - 21…Check valves, 22…Confluence valve, 23…Bleed-off valve, 23a…Command pressure port, 24…Bleed-off valve, 24a…Command pressure port, 25…Relief valve, 26, 27…Check valves, 40…Pump flow path, 41 - 48…Meter-in flow paths, 50…Pump flow path, 51 - 60…Meter-in flow paths, 63 - 74…Flow paths, 91, 92…Pressure sensors (pump pressure sensors), 93 - 100…Pressure sensors (actuator pressure sensors), 111…Pilot pump, 112…Pilot relief valve, 113…Solenoid valve unit, 113a - 113j…Solenoid valves, 114…Controller, 114a…Actuator required speed calculation unit, 114b…Actuator target pressure calculation unit, 114c…Valve first target opening calculation unit, 114d…Valve first estimated flow rate calculation unit, 114e…Confluence ratio calculation unit, 114f…Actuator estimated speed calculation unit, 114g…Actuator estimated flow rate calculation unit, 114h…Valve second estimated flow rate calculation unit, 114i…Valve required flow rate calculation unit, 114j…Valve final estimated flow rate calculation unit, 114k…Valve second target opening calculation unit, 114l…Valve final target opening calculation unit, 114m…Direction control valve control command output unit, 114n…Pump target pressure calculation unit, 114o…Pump target flow rate calculation unit, 114p…Pump flow control command output unit, 114q…Bleed-off valve target opening calculation unit, 114r…Bleed-off valve control command output unit, 115a…Boom operation lever, 115b…Arm operation lever, 116,117... flow path, 131~140... ammeters, 201... traveling body, 202... slewing body (vehicle body), 203... working device, 204... boom, 204a... boom cylinder (actuator), 205... arm, 205a... arm cylinder (actuator), 206... bucket, 206a... bucket cylinder (actuator), 207... driver's cab, 208... machine room, 209... counterweight, 210... control valve, 211... slewing motor (actuator), 212~216... inertial measurement unit (operating state sensor), 901... hydraulic excavator (working machine), 902... hydraulic drive device.,

Claims

1. A vehicle body, a working device attached to the vehicle body, a hydraulic pump, an actuator for driving the vehicle body or the working device, a first direction control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the actuator, an operation lever for instructing the operation of the actuator, In a working machine comprising a controller for controlling the first direction control valve according to the input force of the operation lever, it is provided with an actuator pressure sensor for detecting the actuator pressure which is the load pressure of the actuator, The controller, calculates an actuator target pressure which is the target pressure of the actuator based on the input force of the operation lever, calculates the target opening of the first direction control valve for reducing the difference between the actuator target pressure and the actuator pressure as the valve first target opening, calculates the target opening of the first direction control valve for reducing the difference between the flow rate absorbed by the actuator as the actuator is driven and the flow rate supplied from the hydraulic pump to the actuator as the valve second target opening, calculates the valve final target opening which is the final target opening of the first direction control valve based on the valve first target opening and the valve second target opening, and controls the first direction control valve according to the valve final target opening A working machine characterized by this.

2. In the working machine according to Claim 1, it is provided with a pump pressure sensor for detecting the pump pressure which is the discharge pressure of the hydraulic pump, and a motion state sensor for measuring the posture and motion speed of the vehicle body and the working device, The controller, calculates a valve first estimated flow rate which is a provisional estimated value of the flow rate of the first direction control valve based on the information obtained from the actuator pressure sensor and the pump pressure sensor, calculates a valve second estimated flow rate which is a provisional estimated value of the flow rate of the first direction control valve based on the information obtained by the motion state sensor, calculates a valve final estimated flow rate which is the final estimated value of the flow rate of the first direction control valve based on the valve first estimated flow rate and the valve second estimated flow rate, and calculates the valve second target opening based on the valve final estimated flow rate, the pump pressure, and the actuator target pressure A working machine characterized by this.

3. In the working machine according to Claim 2, A plurality of direction control valves including the first direction control valve for controlling the flow of pressure oil supplied from the hydraulic pump to the actuator is provided. The controller calculates an estimated actuator flow rate, which is an estimated value of the flow rate supplied to the actuator, based on the information acquired by the operating state sensor. calculates a confluence ratio as the ratio of the first valve estimated flow rate of the first direction control valve to the total of the first valve estimated flow rates of the plurality of direction control valves. calculates a value obtained by multiplying the estimated actuator flow rate by the confluence ratio as the second valve estimated flow rate. The construction machine is characterized by the above.

4. In the construction machine according to claim 2, the controller calculates a weighted average of the first valve estimated flow rate and the second valve estimated flow rate as the final valve estimated flow rate, using the deviation rate of the second valve estimated flow rate with respect to the first valve estimated flow rate as the weight coefficient of the first valve estimated flow rate, and a value obtained by subtracting the deviation rate from 1 as the weight coefficient of the second valve estimated flow rate. The construction machine is characterized by the above.

5. In the construction machine according to claim 2, the controller calculates an actuator required speed, which is the operating speed required for the actuator, based on the input force of the operation lever. calculates a required valve flow rate, which is the flow rate required for the first direction control valve, based on the actuator required speed. calculates a weighted average of the first valve estimated flow rate and the second valve estimated flow rate as the final valve estimated flow rate, using the product of the deviation rate of the second valve estimated flow rate with respect to the first valve estimated flow rate and the deviation rate of the second valve estimated flow rate with respect to the required valve flow rate as the weight coefficient of the first valve estimated flow rate, and a value obtained by subtracting the product from 1 as the weight coefficient of the second valve estimated flow rate. The construction machine is characterized by the above.

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