Working machine

Abstract

To provide a work machine which can maintain balance of operation speeds of a plurality of hydraulic actuators, under output restriction of an engine.SOLUTION: A work machine calculates a pump flow rate limit value of pressure oil that can be discharged by a hydraulic pump, on the basis of a prescribed output limit value of an engine and a discharge pressure of a hydraulic pump detected by a discharge pressure sensor, calculates required speeds of each of a plurality of hydraulic actuators, on the basis of an operation amount detected by an operation amount detection sensor, calculates a pump flow rate estimation value that is an estimation value of a flow rate of pressure oil to be discharged by the hydraulic pump so as to satisfy a plurality of calculated required speeds, corrects each of the plurality of required speeds and calculates a plurality of target speeds, on the basis of the pump flow rate limit value and the pump flow rate estimation value, and controls at least one of the engine, the hydraulic pump and a plurality of flow rate control valves so that each of the plurality of hydraulic actuators is operated at the target speed.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a work machine including a plurality of hydraulic actuators.

Background Art

[0002] In a work machine such as a hydraulic excavator, each link such as a boom and an arm constituting a working device is connected by a rotational or linear joint and moves rotationally or translationally by a hydraulic actuator (for example, a hydraulic motor, a hydraulic cylinder). The hydraulic actuator operates by hydraulic oil supplied from a hydraulic pump that is rotationally driven by a prime mover (for example, an engine, an electric motor).

[0003] In order to control the speed, acceleration, and force of the working device, it is necessary to control the rotational torque or thrust applied to each joint. On the other hand, since there is an upper limit to the output energy and torque of the prime mover, when the driving energy of the hydraulic actuator becomes excessive, it is necessary to control so as not to exceed the upper limit of the output energy of the prime mover, such as reducing the discharge capacity of a variable displacement hydraulic pump.

[0004] In order to solve such problems, for example, Patent Document 1 discloses a method of controlling the discharge capacity of a pump within a range not exceeding the output energy of a prime mover by calculating a flow rate limit value by dividing an energy limit value by the current pump discharge pressure.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, when multiple hydraulic actuators are operated in a combined manner, if energy is restricted by the method of Patent Document 1, the balance of the operating speeds of the respective hydraulic actuators may be disrupted. As a result, there arises a problem that the operation of the working machine becomes unintended by the user.

[0007] The present invention has been made in view of the above-described actual situation, and an object thereof is to provide a working machine capable of maintaining the balance of the operating speeds of a plurality of hydraulic actuators under the output limit of the prime mover.

Means for Solving the Problem

[0008] In order to achieve the above object, the present invention provides a working machine including a prime mover that generates driving force, a hydraulic pump that discharges pressure oil by the driving force of the prime mover, a discharge pressure sensor that detects the discharge pressure of the hydraulic pump, a plurality of hydraulic actuators that are operated by the pressure oil supplied from the hydraulic pump, a plurality of flow control valves that control the supply displacement of the pressure oil for each of the plurality of hydraulic actuators, an operating device that operates each of the plurality of hydraulic actuators, an operation amount detection sensor that detects the operation amount by the operating device, and a controller that controls at least one of the prime mover, the hydraulic pump, and the plurality of flow control valves. The controller calculates a pump flow rate limit value of the pressure oil that the hydraulic pump can discharge based on a preset output limit value of the prime mover and the discharge pressure of the hydraulic pump detected by the discharge pressure sensor, calculates a required speed of each of the plurality of hydraulic actuators based on the operation amount detected by the operation amount detection sensor, calculates a pump flow rate estimated value that is an estimated value of the flow rate of the pressure oil that the hydraulic pump should discharge in order to satisfy the calculated plurality of required speeds, corrects each of the plurality of required speeds based on the ratio of the pump flow rate limit value and the pump flow rate estimated value to calculate a plurality of target speeds, and controls the prime mover, the hydraulic pump, and the plurality of flow control Open the valve control and the flow control valve is controlled by the controller based on the smaller value of the meter-in opening amount calculated based on the operation amount and the target meter-in opening amount calculated based on the operation amount and the discharge pressure of the hydraulic pump characterized by the above.

Effect of the Invention

[0009] According to the present invention, it is possible to maintain the balance of the operating speeds of a plurality of hydraulic actuators under the output limit of the prime mover. Incidentally, problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0011] An embodiment of a hydraulic excavator 1 (working machine) according to the present invention will be described with reference to the drawings. Note that a specific example of the working machine is not limited to the hydraulic excavator 1, and may be a wheel loader, a crane, a dump truck, or the like. In addition, the front, rear, left, and right in this specification are based on the perspective of an operator who boards and operates the hydraulic excavator 1 unless otherwise specified.

[0012] FIG. 1 is a side view of the hydraulic excavator 1. As shown in FIG. 1, the hydraulic excavator 1 includes a lower traveling body 2 and an upper swing body 3 supported by the lower traveling body 2. The lower traveling body 2 and the upper swing body 3 are an example of a vehicle body. The lower traveling body 2 includes a pair of left and right crawlers 4 that are endless tracks. Then, by driving the traveling motor 5, the pair of left and right crawlers 4 rotate independently. As a result, the hydraulic excavator 1 travels. However, the lower traveling body 2 may be wheel-mounted instead of the crawlers 4.

[0013] The upper swing body 3 is supported by the lower traveling body 2 so as to be swingable by a swing motor 6. The upper swing body 3 mainly includes a swing frame 7 as a base, a cab (driver's seat) 8 disposed on the front left side of the swing frame 7, a counterweight 9 disposed at the rear of the swing frame 7, and a front working machine 10 (working device) pivotally attached to the front center of the swing frame 7 in the vertical direction.

[0014] An internal space for an operator to operate the hydraulic excavator 1 is formed in the cab 8. And in the internal space of the cab 8, a seat on which the operator sits and an operating device operated by the operator sitting on the seat are arranged.

[0015] The operating device receives the operator's operations for operating the hydraulic excavator 1. When the operating device is operated by the operator, the lower traveling body 2 travels, the upper swing body 3 swings, and the front working machine 10 operates. Specific examples of the operating device include a lever, a steering wheel, an accelerator pedal, a brake pedal, a switch, etc. The operating device includes at least a boom operation lever 41, an arm operation lever 42, and an EC dial 43, as will be described later with reference to FIG. 3, for example.

[0016] The front working machine 10 includes a boom 11 supported by the upper swing body 3 so as to be able to rise and fall, an arm 12 rotatably supported at the tip of the boom 11, a bucket 13 rotatably supported at the tip of the arm 12, a boom cylinder 14 for driving the boom 11, an arm cylinder 15 for driving the arm 12, and a bucket cylinder 16 for driving the bucket 13. The counterweight 9 is for taking a weight balance with the front working machine 10 and is a heavy object having an arc shape in plan view.

[0017] The travel motor 5, the swing motor 6, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16 are an example of a hydraulic actuator (hydraulic actuator) that operates by the supply and discharge of hydraulic oil (pressure oil). That is, the hydraulic excavator 1 is provided with a plurality of hydraulic actuators. However, specific examples of the hydraulic actuator are not limited to these.

[0018] Figure 2 is a diagram showing the drive circuit of the hydraulic excavator 1. In Figure 2, only the hydraulic circuit for driving the boom cylinder 14 and the arm cylinder 15 is illustrated, but the hydraulic excavator 1 also includes a hydraulic circuit for driving other hydraulic actuators (i.e., the travel motor 5, the swing motor 6, and the bucket cylinder 16). As shown in Figure 2, the hydraulic excavator 1 mainly includes an engine 20 (prime mover), a hydraulic oil tank 21, a hydraulic pump 22 (hydraulic pump), direction control valves 23, 24, meter-in control valves 25, 26, opening amount control valves 27, 28, a relief valve 29, a bleed-off valve 30, and pressure sensors 31, 32, 33, 34, 35.

[0019] The engine 20 generates the driving force for driving the hydraulic excavator 1. However, the specific example of the drive source is not limited to the engine 20, and an electric motor or the like may also be used. The hydraulic oil tank 21 stores the hydraulic oil. The hydraulic pump 22 rotates by the driving force of the engine 20 and discharges the hydraulic oil stored in the hydraulic oil tank 21. The hydraulic pump 22 is a variable displacement type such as a swash plate type or a swash shaft type. The discharge capacity of the hydraulic pump 22 is controlled by a regulator 22a.

[0020] The direction control valve 23, the meter-in control valve 25, and the opening amount control valve 27 are hydraulic components for operating (extending and retracting) the boom cylinder 14. The direction control valve 24, the meter-in control valve 26, and the opening amount control valve 28 are hydraulic components for operating (extending and retracting) the arm cylinder 15. Since the configurations of these hydraulic components are common, hereinafter, the hydraulic components 23, 25, 27 for operating the boom cylinder 14 will be described.

[0021] The direction control valve 23 is arranged on the flow path from the hydraulic pump 22 to the boom cylinder 14 and on the flow path from the boom cylinder 14 to the hydraulic oil tank 21. The direction control valve 23 is an electromagnetic proportional control valve that controls the supply direction of the hydraulic oil to the boom cylinder 14 according to the control of the controller 50. More specifically, the direction control valve 23 includes a spool that moves between a stop position A, an extension position B, and a contraction position C when a command current is supplied to ports 23a, 23b.

[0022] The stop position A is the position where the supply and discharge of hydraulic oil to the boom cylinder 14 is stopped. The extension position B is the position where the hydraulic oil discharged from the hydraulic pump 22 is supplied to the bottom chamber of the boom cylinder 14, and the hydraulic oil discharged from the rod chamber of the boom cylinder 14 is refluxed to the hydraulic oil tank 21. Thereby, the boom cylinder 14 extends. The contraction position C is the position where the hydraulic oil discharged from the hydraulic pump 22 is supplied to the rod chamber of the boom cylinder 14, and the hydraulic oil discharged from the bottom chamber of the boom cylinder 14 is refluxed to the hydraulic oil tank 21. Thereby, the boom cylinder 14 contracts. Also, the closer the spool approaches the stop position A, the smaller the supply amount of hydraulic oil to the boom cylinder 14. On the other hand, the closer the spool approaches the extension position B or the contraction position C, the larger the supply amount of hydraulic oil to the boom cylinder 14.

[0023] The initial position of the spool of the direction control valve 23 (the position when no command current is supplied to both ports 23a and 23b) is the stop position A. Also, the spool of the direction control valve 23 moves from the stop position A toward the extension position B when a command current is supplied to port 23a. Further, the spool of the direction control valve 23 moves from the stop position A toward the contraction position C when a command current is supplied to port 23b. Furthermore, the closer the command current supplied to ports 23a and 23b becomes larger, the closer the spool of the direction control valve 23 approaches the extension position B or the contraction position C. On the other hand, when the supply of the command current to ports 23a and 23b is stopped, the spool of the direction control valve 23 returns to the stop position A.

[0024] The meter-in control valve 25 is arranged on the flow path from the hydraulic pump 22 to the direction control valve 23. In other words, the meter-in control valve 25 is arranged upstream of the direction control valve 23. The meter-in control valve 25 controls the flow rate of the hydraulic oil discharged by the hydraulic pump 22 and supplied to the boom cylinder 14 through the direction control valve 23. More specifically, the meter-in control valve 25 increases or decreases the flow rate of the pressure oil supplied to the direction control valve 23 by controlling the back pressure by means of the opening amount control valve 27.

[0025] The opening amount control valve 27 controls the flow rate of the hydraulic oil (i.e., the opening amount of the meter-in control valve 25) supplied from the hydraulic pump 22 to the direction control valve 23 through the meter-in control valve 25 by controlling the back pressure of the meter-in control valve 25. The opening amount control valve 27 is an electromagnetic proportional control valve that controls the flow rate of the hydraulic oil passing through the meter-in control valve 25 according to the control of the controller 50. The opening amount control valve 27 includes a spool that moves between a supply position D and a cutoff position E when a command current is supplied.

[0026] The supply position D is a position where the back pressure port of the meter-in control valve 25 is opened and hydraulic oil is supplied from the hydraulic pump 22 to the direction control valve 23 through the meter-in control valve 25. The cutoff position E is a position where the back pressure port of the meter-in control valve 25 is closed and the supply of hydraulic oil from the hydraulic pump 22 to the direction control valve 23 through the meter-in control valve 25 is cutoff. The closer the spool of the opening amount control valve 27 approaches the supply position D, the greater the supply amount of hydraulic oil to the direction control valve 23, and the closer the spool of the opening amount control valve 27 approaches the cutoff position E, the smaller the supply amount of hydraulic oil to the direction control valve 23.

[0027] The initial position of the spool of the opening amount control valve 27 (the position when no command current is supplied) is the supply position D. Also, when a command current is supplied, the spool of the opening amount control valve 27 moves from the supply position D to the cutoff position E. Further, the greater the command current supplied, the closer the spool of the opening amount control valve 27 approaches the cutoff position E. On the other hand, when the supply of the command current is stopped, the spool of the opening amount control valve 27 returns to the supply position D.

[0028] The direction control valve 23, the meter-in control valve 25, and the opening amount control valve 27 are an example of a flow control valve that controls the supply and discharge amount of hydraulic oil to the boom cylinder 14. However, the specific configuration of the flow control valve is not limited to the above example, and it may be composed of one or more valves directly or indirectly controlled by the controller 50. Also, the flow control valve according to the present embodiment performs a so-called "meter-in control" that controls the flow rate of the hydraulic oil supplied to the hydraulic actuator. However, the method of controlling the flow rate of the hydraulic oil to the hydraulic actuator is not limited to the meter-in control, and it may be a so-called "meter-out control" that controls the flow rate of the hydraulic oil discharged from the hydraulic actuator.

[0029] When the discharge pressure discharged from the hydraulic pump 22 reaches the set pressure, the relief valve 29 returns the pressure oil to the hydraulic oil tank 21 for the purpose of protecting the hydraulic circuit. Also, according to the control of the controller 50, the bleed-off valve 30 adjusts the flow rate of a part of the pressure oil discharged from the hydraulic pump 22 and returns the adjusted flow rate to the hydraulic oil tank 21.

[0030] The pressure sensor 31 (discharge pressure sensor) detects the discharge pressure discharged from the hydraulic pump 22 (hereinafter referred to as "pump discharge pressure Pp"). Also, the pressure sensors 32 and 34 detect the pressure of the hydraulic oil supplied to and discharged from the bottom chambers of the boom cylinder 14 and the arm cylinder 15. Further, the pressure sensors 33 and 35 detect the pressure of the hydraulic oil supplied to and discharged from the rod chambers of the boom cylinder 14 and the arm cylinder 15. Hereinafter, the pressure detected by the pressure sensors 32 to 35 is the measured pressure P actIt is expressed as such. Then, the pressure sensors 31 to 35 output a pressure signal indicating the detected pressure to the controller 50.

[0031] FIG. 3 is a hardware configuration diagram of the hydraulic excavator 1. As shown in FIG. 3, the hydraulic excavator 1 includes a controller 50 having a CPU 51 (Central Processing Unit) and a memory 52. The memory 52 is composed of, for example, a ROM (Read Only Memory), a RAM (Random Access Memory), an HDD (Hard Disk Drive), or a combination thereof. The controller 50 realizes the processing described later by the CPU 51 reading and executing the program code stored in the memory 52.

[0032] However, the specific configuration of the controller 50 is not limited to this, and it may be realized by hardware such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field-Programmable Gate Array).

[0033] The controller 50 controls the engine 20, the regulator 22a, the direction control valves 23, 24, the opening amount control valves 27, 28, and the bleed-off valve 30 based on various signals acquired from the pressure sensors 31 to 35, the attitude sensors 36 to 39, the boom operation lever 41, the arm operation lever 42, and the EC dial 43. That is, the controller 50 controls the rotational speed of the engine 20, the discharge capacity of the hydraulic pump 22, and the opening amounts (the magnitudes of the command currents to be supplied) of the direction control valves 23, 24, the opening amount control valves 27, 28, and the bleed-off valve 30. Also, the controller 50 indirectly controls the opening amounts of the meter-in control valves 25, 26 by controlling the opening amount control valves 27, 28.

[0034] The posture sensors 36 to 39 detect the postures of the joints driven by the hydraulic actuators, and output posture signals indicating the detection results to the controller 50. For example, the posture sensor 36 detects the turning angle of the upper swing body 3, the posture sensor 37 detects the ground angle of the boom 11, the posture sensor 38 detects the angle of the arm 12 with respect to the boom 11, and the posture sensor 39 detects the angle of the bucket 13 with respect to the arm 12. Hereinafter, these angles are denoted as "joint angle θ". However, the specific examples of the postures detected by the posture sensors 36 to 39 are not limited to the above examples.

[0035] The boom operation lever 41 receives the operation of the operator for raising and lowering the boom 11 (in other words, extending and retracting the boom cylinder 14). More specifically, the boom operation lever 41 receives the operation of the operator for indicating the extending and retracting direction of the boom cylinder 14 and the extending and retracting amount (extending and retracting speed) of the boom cylinder 14. For example, the operation of tilting the boom operation lever 41 backward corresponds to an instruction (positive sign) to extend the boom cylinder 14, and the operation of tilting the boom operation lever 41 forward corresponds to an instruction (negative sign) to contract the boom cylinder 14. Further, the operation amount of the boom operation lever 41 corresponds to the absolute value of the extending and retracting amount (extending and retracting speed) of the boom cylinder 14.

[0036] The arm operation lever 42 receives the operation of the operator for rotating the arm 12 (in other words, extending and retracting the arm cylinder 15). More specifically, the arm operation lever 42 receives the operation of the operator for indicating the extending and retracting direction of the arm cylinder 15 and the extending and retracting amount (extending and retracting speed) of the arm cylinder 15. For example, the operation of tilting the arm operation lever 42 to the right corresponds to an instruction (positive sign) to extend the arm cylinder 15, and the operation of tilting the arm operation lever 42 to the left corresponds to an instruction (negative sign) to contract the arm cylinder 15. Further, the operation amount of the arm operation lever 42 corresponds to the absolute value of the extending and retracting amount (extending and retracting speed) of the arm cylinder 15.

[0037] The combination of the expansion / contraction direction and the expansion / contraction amount (expansion / contraction speed) is an example of the operation amount o. However, the specific example of the operation amount o is not limited to the above example. Operation devices such as the boom operation lever 41 and the arm operation lever 42 output an operation signal indicating the operation amount o for the operation device to the controller 50. The boom operation lever 41 and the arm operation lever 42 have an operation amount detection sensor that detects each operation amount o and outputs the operation amount o. Each operation lever for operating each of the traveling motor 5, the slewing motor 6, and the bucket cylinder 16 further includes a respective operation amount detection sensor that outputs each operation amount o. Further, the operation device is not limited to the form of a lever, and may be a pedal, a switch, or the like. Furthermore, the operation amount detection sensor is not limited to a configuration that detects the operation amount o based on the current value output from an operation device such as an operation lever provided in the cab 8, and may be configured to detect the operation amount o via an external server through a communication line from a remote operation device. Based on the operation signals from the above-described respective operation levers, the operation amount o of each operation lever may be calculated by processing in the controller 50, and as a result, the operation amount o may be detected.

[0038] The EC dial (engine control dial) 43 arbitrarily sets the required rotational speed W of the engine 20 by dial operation. r Further, the EC dial 43 outputs a rotational speed command signal indicating the required rotational speed W set by dial operation to the controller 50. The EC dial 43 is an example of an engine rotational speed setting device that sets the required rotational speed W of the engine 20. Note that the engine rotational speed setting device is not limited to the form of a dial, and may be a switch, a touch panel, or the like. Furthermore, the engine rotational speed setting device is not limited to setting the required rotational speed W from a dial or the like provided in the cab 8, and may be configured to set the required rotational speed W via an external server through a communication line from a remote operation device equipped with an engine rotational speed setting device. r r r r

[0039] ​​​​Figure 4 is a functional block diagram of the controller 50. As shown in Figure 4, the controller 50 mainly includes a required speed calculation unit 61, a rotation speed control unit 62, a Jacobian matrix calculation unit 63, an output limit unit 64, a joint torque calculation unit 65, a target pressure calculation unit 66, an actual measured pressure calculation unit 67, a valve control unit 68, and a pump control unit 69. Each of the functional blocks 61 to 69 shown in Figure 4 is realized, for example, by the CPU 51 executing a program stored in the memory 52.

[0040] When each of the functional blocks 61 to 69 shown in Figure 4 operates a plurality of hydraulic actuators in parallel (hereinafter referred to as "compound operation"), at least one of the engine 20, the hydraulic pump 22, the direction control valves 23, 24, and the opening amount control valves 27, 28 is controlled so that the output of the engine 20 is within the range of the output limit value E while maintaining the balance of the operating speeds of the respective hydraulic actuators. Hereinafter, an example of the compound operation of the boom cylinder 14 and the arm cylinder 15 will be described.

[0041] Based on the operation amount o obtained through the boom operation lever 41 and the arm operation lever 42, the required speed calculation unit 61 calculates the required speeds v r of the boom cylinder 14 and the arm cylinder 15. The required speed v r is the expansion and contraction speed of the boom cylinder 14 and the arm cylinder 15 corresponding to the operation amounts of the boom operation lever 41 and the arm operation lever 42.

[0042] Figure 5 is a detailed diagram of the required speed calculation unit 61. As shown in Figure 5, the required speed calculation unit 61 has required speed tables 611 and 612 corresponding to each hydraulic actuator. The required speed table 611 holds a predetermined correspondence relationship between the operation amount o obtained through the boom operation lever 41 and the required speed v r-Bm of the boom 11. The required speed table 612 holds a predetermined correspondence relationship between the operation amount o obtained through the arm operation lever 42 and the required speed v r-Am of the arm 12. More specifically, the required speed tables 611 and 612 increase the required speed v r-Bm, v r-Am maintains the relationship of increasing speed.

[0043] Although illustration is omitted, the memory 52 stores a required speed table corresponding to the traveling motor 5, the slewing motor 6, and the bucket cylinder 16. Further, the required speed calculation unit 61 may have an individual required speed table for each hydraulic actuator, or may have a multidimensional table that outputs a plurality of required speeds for a plurality of input operation amounts.

[0044] Based on the required speed table 611, the required speed calculation unit 61 calculates the required speed v corresponding to the operation amount o obtained through the boom operation lever 41. r-Bm Also, based on the required speed table 612, the required speed calculation unit 61 calculates the required speed v corresponding to the operation amount o obtained through the arm operation lever 42. r-Am Then, as shown in FIG. 4, the required speed calculation unit 61 outputs the calculated required speed v r (v r-Bm , v r-Am (vector including ) to the output limit unit 64.

[0045] Based on the required rotation speed W obtained through the EC dial 43, the rotation speed control unit 62 calculates the target rotation speed W r and the output limit value E. The target rotation speed W E-t is the target value of the rotation speed of the engine 20. The output limit value E is the limit value (limit) of the output when the engine 20 is rotated at the target rotation speed W E-t . E-t FIG. 6 is a detailed view of the rotation speed control unit 62. As shown in FIG. 6, the rotation speed control unit 62 has a target rotation speed table 621 and an output limit value table 622. The target rotation speed table 621 maintains a predetermined correspondence between the required rotation speed W

[0046] and the target rotation speed W r . More specifically, when the required rotation speed W E-t is smaller than the lower limit value, the target rotation speed table 621 has the target rotation speed W r and the target rotation speed W E-tis constant at the minimum value, and the required rotational speed W r When it is greater than the upper limit value, the target rotational speed W E-t is constant at the maximum value, and the required rotational speed W r is between the lower limit value and the upper limit value, and the required rotational speed W r The greater it is, the greater the target rotational speed W E-t maintains the relationship of increasing. The output limit value table 622 stores the target rotational speed W E-t and the predetermined correspondence relationship with the output limit value E. More specifically, the output limit value E maintains the relationship that as the target rotational speed W E-t increases, the output limit value E increases.

[0047] Based on the target rotational speed table 621, the rotational speed control unit 62 calculates the target rotational speed W r corresponding to the required rotational speed W E-t In addition, based on the output limit value table 622, the rotational speed control unit 62 calculates the output limit value E corresponding to the target rotational speed W E-t As shown in FIG. 4, the rotational speed control unit 62 outputs the calculated target rotational speed W E-t to the pump control unit 69 and outputs the calculated output limit value E to the output limit unit 64. Also, the rotational speed control unit 62 outputs the calculated target rotational speed W E-t to an engine controller (not shown) to control the rotational speed of the engine 20 to be the target rotational speed W E-t

[0048] Based on the joint angles θ detected by the attitude sensors 37 and 38, the Jacobian matrix calculation unit 63 calculates the Jacobian matrix J. The Jacobian matrix J is a conversion coefficient that converts the displacement speed of the hydraulic actuator into the target joint angular velocity vector ω’t (in other words, converts the link angular velocity system into the actuator speed system). The specific method of calculating the Jacobian matrix J is already well-known as described in, for example, Non-Patent Document 1, so detailed description is omitted. Then, the Jacobian matrix calculation unit 63 outputs the calculated Jacobian matrix J to the joint torque calculation unit 65.

[0049] ​The output limiting unit 64 calculates the target speed v r based on the required speed v obtained from the required speed calculation unit 61, the output limit value E obtained from the rotational speed control unit 62, and the pump discharge pressure Pp detected by the pressure sensor 31. t The target acceleration v' t and the target pump flow rate Q p-t are also calculated. The target speed v t is the target value (v t-Bm , v t-Am ) of the extension and retraction speeds of the boom cylinder 14 and the arm cylinder 15 respectively. The target acceleration v' t is the target value (v' t-Bm , v' t-Am ) of the acceleration for extending and retracting the boom cylinder 14 and the arm cylinder 15 at the target speeds v t-Bm , v t-Am . The target pump flow rate Q p-t is the target value of the discharge capacity of the hydraulic pump 22 required to extend and retract the boom cylinder 14 and the arm cylinder 15 at the target speeds v t -Bm, v t-Am .

[0050] Figure 7 is a detailed diagram of the output limiting unit 64. As shown in Figure 7, the output limiting unit 64 includes calculation units 641 to 646.

[0051] The calculation unit 641 calculates the pump flow rate limit value Q lim by dividing the output limit value E by the pump discharge pressure Pp. The pump flow rate limit value Q lim is the upper limit value (limit value) of the discharge capacity of the hydraulic pump 22 when the output of the engine 20 is within the output limit value E. Then, the calculation unit 641 outputs the calculated pump flow rate limit value Q lim to the calculation unit 643.

[0052] The calculation unit 642 calculates the required speed v r (v r-Bm , v r-Am ) obtained from the required speed calculation unit 61 and the cross-sectional area S of the oil path of the corresponding hydraulic actuator (S -Bm , S -AmBy integrating the product with [ ], the estimated pump flow rate Q est is calculated. The estimated pump flow rate Q est is an estimated value of the flow rate of the hydraulic oil that the hydraulic pump 22 should discharge in order to satisfy a plurality of required speeds v r-Bm , v r-Am calculated by the required speed calculation unit 61. Then, the calculation unit 642 outputs the calculated estimated pump flow rate Q est to the calculation units 643 and 646.

[0053] The calculation unit 643 calculates the speed limit gain K by dividing the pump flow rate limit value Q lim by the estimated pump flow rate Q est (that is, the ratio of the pump flow rate limit value Q lim and the estimated pump flow rate Q est ). The speed limit gain K is a correction coefficient for correcting the required speed v r and the estimated pump flow rate Q est . When restricting the operation of the hydraulic actuator within the range of the output limit value E, the pump flow rate limit value Q lim is smaller than the estimated pump flow rate Q est , so the speed limit gain K satisfies 0 ≤ K < 1. Then, the calculation unit 643 outputs to the minimum value selection unit 647.

[0054] The minimum value selection unit 647 selects the smaller value between the speed limit gain K output from the calculation unit 643 and a predetermined fixed value (= 1). Then, the minimum value selection unit 647 outputs the selected value as the speed limit gain K to the calculation units 644 and 646. That is, when the speed limit gain K output from the calculation unit 643 is less than 1, the minimum value selection unit 647 outputs this speed limit gain K as it is. On the other hand, when the speed limit gain K output from the calculation unit 643 is 1 or more, the minimum value selection unit 647 substitutes 1 into the speed limit gain K and outputs it.

[0055] The calculation unit 644 multiplies each of the plurality of required speeds v r-Bm , v r-Am by the speed limit gain K to obtain the target speed v t (v t-Bm, v t-Am (a vector including) is calculated. That is, the calculation unit 644 calculates the pump flow rate limit value Q lim and the pump flow rate estimated value Q est . Based on the ratio of, for a plurality of required speeds v r-Bm , v r-Am respectively, corrects them to calculate a plurality of target speeds v t-Bm , v t-Am . Then, the calculation unit 644 outputs the calculated target speed v t to the calculation unit 645 and the joint torque calculation unit 65.

[0056] The calculation unit 645 differentiates each of the plurality of required speeds v r-Bm , v r-Am with respect to time t to calculate a required acceleration v’ r (a vector including v’ r-Bm , v’ r-Am ). Then, the calculation unit 645 outputs the calculated required acceleration v’ r to the joint torque calculation unit 65.

[0057] The calculation unit 646 multiplies the pump flow rate estimated value Q est by a speed limit gain K to calculate a target pump flow rate Q p-t . That is, the calculation unit 646 corrects the pump flow rate estimated value Q lim based on the ratio of the pump flow rate limit value Q est and the pump flow rate estimated value Q est to calculate a target pump flow rate Q p-t . Then, the calculation unit 646 outputs the calculated target pump flow rate Q p-t to the pump control unit 69.

[0058] The joint torque calculation unit 65 substitutes the joint angle θ detected by the attitude sensors 37 and 38, the joint angular velocity θ’ obtained by differentiating the joint angle θ with respect to time, the target speed v t and the target acceleration v’t obtained from the output restriction unit 64 into the following formulas 1 and 2 to calculate a target torque ft. The target torque ft is for the boom cylinder 14 and the arm cylinder 15 to reach the target speeds v t-Bm , vt-Am The target value of torque (ft -Bm , ft -Bm ) when it is expanded and contracted.

[0059] [Number] [Number]

[0060] First, the joint torque calculation unit 65 substitutes the target speeds v t-Bm , v t-Am respectively and the Jacobian matrix J into Equation 1 to calculate the target joint angular velocity vector ω’t. Further, the joint torque calculation unit 65 substitutes the joint angle θ, the joint angular velocity θ’, and the target joint angular velocity vector ω’t into the equation of motion of Equation 2 to calculate the target torque ft. Then, the joint torque calculation unit 65 outputs the calculated target torque ft to the target pressure calculation unit 66.

[0061] Here, among the right side of Equation 2, the first term is the inertia term of the link member, the second term is the centripetal force·Coriolis force term (C) and the friction term (D), and the third term is the gravity term (g is the gravitational acceleration). Note that the link member dimensions, weights, frictions, and other information for calculating the coefficients of each term are assumed to be known. The calculation method by the joint torque calculation unit 65 is known as the computed torque method and is already well-known as described in, for example, Non-Patent Document 2, so detailed description is omitted.

[0062] The target pressure calculation unit 66 calculates the target pressures (target meter-in pressure P mi-t , target meter-out pressure P mo-t ) of the pressure oil supplied to and discharged from each of the boom cylinder 14 and the arm cylinder 15 based on the corresponding target speed v t . More specifically, the target pressure calculation unit 66 calculates the target meter-in pressure P mi-t and the target meter-out pressure P based on the operation amount o obtained through the boom operation lever 41 and the arm operation lever 42 and the target torque ft obtained from the joint torque calculation unit 65.mo-t calculates the meter-in flag σmi and the like.

[0063] Target meter-in pressure P mi-t is the target value of the pressure of the hydraulic oil supplied to each of the boom cylinder 14 and the arm cylinder 15 in order to expand and contract them at the target speeds v t-Bm and v t-Am respectively. The target meter-out pressure P mo-t is the target value of the pressure of the hydraulic oil discharged from each of the boom cylinder 14 and the arm cylinder 15 in order to expand and contract them at the target speeds v t-Bm and v t-Am respectively. The meter-in flag σmi is a value indicating whether to supply the hydraulic oil to the bottom chamber or the rod chamber.

[0064] FIG. 8 is a detailed diagram of the target pressure calculation unit 66 applied to the hydraulic cylinders (that is, the boom cylinder 14, the arm cylinder 15, and the bucket cylinder 16) of the hydraulic actuator. FIG. 9 is a detailed diagram of the target pressure calculation unit 66 applied to the hydraulic motors (that is, the travel motor 5 and the swing motor 6) of the hydraulic actuator. As shown in FIGS. 8 and 9, the target pressure calculation unit 66 has target pressure calculation tables 661 and 662. The target pressure calculation tables 661 and 662 hold the correspondence relationship between the combination of the operation amount o and the target torque ft and the calculation methods of the target meter-in pressure P mi-t and the target meter-out pressure P mo-t and the meter-in flag σmi.

[0065] As shown in FIGS. 8 and 9, when the operation amount o is equal to or greater than the positive threshold value th1, the target pressure calculation unit 66 sets the bottom (= 1) to the meter in flag σmi. On the other hand, when the operation amount o is equal to or less than the negative threshold value -th1, the target pressure calculation unit 66 sets the rod (= -1) to the meter in flag σmi. On the other hand, when the operation amount o is less than the positive threshold value th1 and greater than the negative threshold value -th1, it is determined that the hydraulic actuator is stopped. Then, as shown in FIG. 4, the target pressure calculation unit 66 outputs the calculated meter in flag σmi to the measured pressure calculation unit 67.

[0066] Further, the target pressure calculation unit 66 calculates the target meter in pressure P mi-t and the target meter out pressure P mo-t according to the combination of the operation amount o and the target torque ft. Here, the constants p _buf1 and p _buf2 are fixed values set in advance as the minimum pressure to prevent cavitation. Also, the constants S b and S r are the cross-sectional areas of the bottom side (S b ) and the rod side (S r ) of the hydraulic cylinder, respectively. Furthermore, the motor volume q m is the motor volume of the hydraulic motor, and when there is a speed reducer, it is a value considering the reduction ratio. That is, for the hydraulic cylinder and the hydraulic motor, the calculation formulas of the target meter in pressure P mi-t and the target meter out pressure P mo-t are different. Then, as shown in FIG. 4, the target pressure calculation unit 66 outputs the calculated target meter in pressure P mi-t and the target meter out pressure P mo-t to the valve control unit 68 and the pump control unit 69.

[0067] The measured pressure calculation unit 67 substitutes the measured pressure P act detected by the pressure sensors 32 to 35 and the meter in flag σmi obtained from the target pressure calculation unit 66 into the following formula 3 to calculate the measured meter in pressure P mi and the measured meter out pressure P mo . The measured meter in pressure P miis the measured value of the hydraulic oil supplied to the boom cylinder 14 and the arm cylinder 15. The measured meter out pressure P mo is the measured value of the hydraulic oil discharged from the boom cylinder 14 and the arm cylinder 15.

[0068]

Number

[0069] In Equation 3, the measured pressure Pa is the measured pressure detected by the bottom side pressure sensors 32 and 34, and the measured pressure Pb is the measured pressure detected by the rod side pressure sensors 33 and 35. Then, the measured pressure calculation unit 67 calculates the measured meter in pressure P mi , and the measured meter out pressure P mo and outputs them to the valve control unit 68.

[0070] Figure 10 is a detailed diagram of the valve control unit 68 that performs meter in control. The valve control unit 68 in Figure 10 includes the operation amount o obtained through the boom operation lever 41 and the arm operation lever 42, the target meter in pressure P mi-t obtained from the target pressure calculation unit 66, the measured meter in pressure P mi obtained from the measured pressure calculation unit 67, the pump discharge pressure Pp detected by the pressure sensor 31, the meter in oil passage volume V mi , and the meter in oil passage volume change amount V’ mi and calculates the valve opening command i based on them. The valve control unit 68 includes a meter in opening limit value table 681A, calculation units 682A to 685A, and a valve opening command table 686A.

[0071] The meter in oil passage volume V mi is the volume of the hydraulic oil to be supplied to each of the boom cylinder 14 and the arm cylinder 15. The meter in oil passage volume change amount V’ mi is the volume of the hydraulic oil to be supplied to each of the boom cylinder 14 and the arm cylinder 15 per unit time. The valve opening command i is for the boom cylinder 14 and the arm cylinder 15 to reach the target speeds v t-Bm , vt-Am It is a value (for example, the magnitude of the command current supplied to each of the opening amount control valves 27 and 28) indicating the opening amount of each of the meter-in control valves 25 and 26 necessary for expansion and contraction.

[0072] When the hydraulic actuator is a hydraulic cylinder, the meter-in oil passage volume V mi , the meter-in oil passage volume change amount V' mi is specified by the following formula 4. On the other hand, when the hydraulic actuator is a hydraulic motor, the meter-in oil passage volume V mi , the meter-in oil passage volume change amount V' mi is specified by the following formula 5. Note that the initial volumes V a0 , V b0 are the initial values of the oil passage volumes on the bottom side (V a0 ) and the rod side (V b0 ) of the hydraulic cylinder, respectively. Also, the cylinder displacement Xc is the displacement amounts of the boom cylinder 14 and the arm cylinder 15. Also, Smi and Smo are the meter-in side cylinder cross-sectional area and the meter-out side cylinder cross-sectional area, respectively. Further, q m is the motor volume of the above-described hydraulic motor.

[0073]

Equation

[0074]

Equation

[0075] The meter-in opening limit value table 681A holds a predetermined correspondence relationship between the operation amount o and the meter-in opening limit value A mi-lim . More specifically, the meter-in opening limit value table 681A holds a relationship in which the meter-in opening limit value A mi-lim increases as the operation amount o increases. The meter-in opening limit value A mi-limis the limit value of the opening area in the meter-in control valves 25 and 26. And the meter-in opening limit value A specified based on the meter-in opening limit value table 681A mi-lim is output to the arithmetic unit 685A.

[0076] The arithmetic unit 682A subtracts the measured meter-in pressure P mi-t from the target meter-in pressure P mi and outputs it to the arithmetic unit 683A. The arithmetic unit 682A calculates the feedback control amount V from the calculation result of the arithmetic unit 682A by PID (Proportional-Integral-Differential) control, and outputs the calculated feedback control amount V to the arithmetic unit 684A. The arithmetic unit 684A calculates the target meter-in opening amount A' mi by substituting the measured meter-in pressure P mi the pump discharge pressure Pp, the meter-in oil passage volume V mi the meter-in oil passage volume change amount V', and the feedback control amount V into the following formula 7. The target meter-in opening amount A' mi-t is the target value of the opening area in the meter-in control valves 25 and 26. mi-t is the target value of the opening area in the meter-in control valves 25 and 26.

[0077] mi-t and outputs it to the arithmetic unit 685A.

[0078]

Equation

[0079]

Equation

[0080] ​The calculation unit 685A outputs the smaller value of the meter-in opening limit value A mi-lim and the target meter-in opening amount A' mi-t to the valve opening command table 686A. The valve opening command table 686A holds a predetermined correspondence relationship between the output value of the calculation unit 685A and the valve opening command i. More specifically, the valve opening command table 686A holds a relationship such that the larger the output value of the calculation unit 685A, the larger the valve opening command i. Then, the valve control unit 68 controls the opening amounts of the opening amount control valves 27 and 28 according to the valve opening command i specified based on the valve opening command table 686A. For example, the valve control unit 68 supplies the command current indicated by the valve opening command i to the opening amount control valves 27 and 28.

[0081] FIG. 11 is a detailed diagram of the valve control unit 68 that performs meter-out control. The valve control unit 68 in FIG. 11 calculates a valve opening command i based on the operation amount o obtained through the boom operation lever 41 and the arm operation lever 42, the target meter-out pressure P mo-t acquired from the target pressure calculation unit 66, the measured meter-out pressure P mo acquired from the measured pressure calculation unit 67, the discharge-side pressure P ret , the meter-out oil passage volume V mo , and the meter-out oil passage volume change amount V' mo . The valve control unit 68 includes a meter-out opening limit value table 681B, calculation units 682B to 685B, and a valve opening command table 686B.

[0082] The meter-out oil passage volume V mo is the volume of the hydraulic oil to be discharged from each of the boom cylinder 14 and the arm cylinder 15. The meter-out oil passage volume change amount V' mo is the volume of the hydraulic oil to be discharged from each of the boom cylinder 14 and the arm cylinder 15 per unit time. The discharge-side pressure P ret is the pressure of the hydraulic oil discharged into the hydraulic oil tank 21 (usually, the pressure inside the hydraulic oil tank 21). The valve opening command i causes each of the boom cylinder 14 and the arm cylinder 15 to move at a target speed v t-Bm , vt-Am It is a value indicating the opening amount of the flow control valve on the meter-out side (for example, the flow control valve 72 in FIG. 13) necessary for expansion and contraction.

[0083] When the hydraulic actuator is a hydraulic cylinder, the meter-out oil passage volume V mo and the meter-out oil passage volume change amount V' mo are specified by the above formula 4. On the other hand, when the hydraulic actuator is a hydraulic motor, the meter-out oil passage volume V mo and the meter-out oil passage volume change amount V' mo are specified by the above formula 5.

[0084] The meter-out opening limit value table 681B holds a predetermined correspondence relationship between the operation amount o and the meter-out opening limit value A mo-lim . More specifically, the meter-out opening limit value table 681B holds a relationship in which the larger the operation amount o, the larger the meter-out opening limit value A mo-lim . The meter-out opening limit value A mo-lim is the limit value of the opening area in the flow control valve 72. And the meter-out opening limit value A mo-lim specified based on the meter-out opening limit value table 681B is output to the arithmetic unit 685B.

[0085] The arithmetic unit 684B substitutes the measured meter-out pressure P mo , the discharge side pressure P ret , the meter-out oil passage volume V mo , the meter-out oil passage volume change amount V' mo , and the feedback control amount V into the following formula 9 to calculate the target meter-out opening amount A' mo-t . The target meter-out opening amount A' mo-t is the target value of the opening area in the flow control valve 72. More specifically, when formula 8 is rearranged with respect to the feedback control amount V, formula 9 is obtained. And the arithmetic unit 684B outputs the calculated target meter-out opening amount A' mo-t to the arithmetic unit 685B.

[0086]

Number

[0087]

Number

[0088] Note that although the processing contents of the arithmetic units 682B to 685B are different in the specific parameters used, they are common to the arithmetic units 682A to 685A shown in FIG. 10. Also, although the valve opening command table 686B has different specific input parameters, its basic content is common to the valve opening command table 686A shown in FIG. 10. That is, the valve control unit 68 shown in FIGS. 10 and 11 controls the opening amounts of the plurality of flow control valves based on the differences between the corresponding target pressures and the measured pressures.

[0089] The pump control unit 69 calculates the target pump capacity q based on the pump discharge pressure Pp detected by the pressure sensor 31, the target pump flow rate Q obtained from the output limiting unit 64, the target rotation speed W obtained from the rotation speed control unit 62, and the target meter-in pressure P obtained from the target pressure calculation unit 66. p-t and the target rotation speed W obtained from the rotation speed control unit 62 E-t and the target meter-in pressure P obtained from the target pressure calculation unit 66 mi-t and. p-t The target pump capacity q p-t is the target value of the discharge capacity of the hydraulic pump 22 required to extend and retract the boom cylinder 14 and the arm cylinder 15 at the target speeds v t-Bm , v t-Am respectively.

[0090] FIG. 12 is a detailed diagram of the pump control unit 69. As shown in FIG. 12, the pump control unit 69 includes arithmetic units 691 to 695.

[0091] The arithmetic unit 691 processes a plurality of target meter-in pressures P mi-tOutputs the maximum value among them to the arithmetic unit 692. The arithmetic unit 692 subtracts the pump discharge pressure Pp from the maximum value obtained from the arithmetic unit 691 and outputs the result to the arithmetic unit 693. The arithmetic unit 693 calculates the pump flow rate correction value Z from the calculation result of the arithmetic unit 692 by PID control and outputs the calculated pump flow rate correction value Z to the arithmetic unit 694. The arithmetic unit 693 adds the pump flow rate correction value Z to the target pump flow rate Q p-t to calculate the corrected target pump flow rate Q' p-t and outputs the corrected target pump flow rate Q' p-t to the arithmetic unit 695. The arithmetic unit 695 divides the corrected target pump flow rate Q' p-t by the target rotational speed W E-t to calculate the target pump displacement q p-t . Then, the pump control unit 69 controls the regulator 22a so that the hydraulic oil of the calculated target pump displacement q p-t is discharged from the hydraulic pump 22.

[0092] According to the above embodiment, for example, the following operational effects can be obtained.

[0093] According to the above embodiment, the required speeds v r-Bm , v r-Am of the boom cylinder 14 and the arm cylinder 15 are divided by the common speed limit gain K to calculate the target speeds v t-Bm , v t-Am . As a result, even when the output of the engine 20 is limited to the output limit value E, the balance of the extension and retraction speeds of the boom cylinder 14 and the arm cylinder 15 (i.e., the operating speeds of the boom 11 and the arm 12) can be maintained.

[0094] As a result, although the moving speed of the arm 12 becomes slower than intended by the operator, the arm 12 moves along the trajectory intended by the operator. Thus, for example, even in the case of a horizontal pulling operation in which the boom cylinder 14 and the arm cylinder 15 are operated in combination to horizontally move the tip of the bucket 13 in order to level the earth and sand at the tip of the bucket 13, the balance of the operating speeds of the boom cylinder 14 and the arm cylinder 15 can be maintained.

[0095] In the above-described embodiment, an example was described in which the opening amounts of the meter-in control valves 25 and 26 are indirectly controlled by adjusting the magnitude of the command current supplied to the opening amount control valves 27 and 28. However, in order to expand and contract the boom cylinder 14 and the arm cylinder 15 at the target speeds v t-Bm , v t-Am , the object to be directly controlled is not limited to the above example. As another example, the meter-in control valves 25 and 26 may be directly controlled as electromagnetic proportional valves.

[0096] Further, in the above-described embodiment, in the schematic diagram of the hydraulic circuit shown in FIG. 13, an example was described in which the opening amount of the meter-in side flow control valve 71 that controls the supply amount Ami of the hydraulic oil to the boom cylinder 14 and the arm cylinder 15 is controlled. However, the opening amount of the meter-out side flow control valve 72 that controls the discharge amount Amo of the hydraulic oil from the boom cylinder 14 and the arm cylinder 15 may be controlled.

[0097] Furthermore, in the above-described embodiment, an example was described in which the boom cylinder 14 and the arm cylinder 15 are operated in a combined manner. However, the combination of the hydraulic actuators that are operated in a combined manner is not limited to the above example. FIG. 14 is a drive path diagram showing another combination of the hydraulic actuators that are operated in a combined manner.

[0098] As shown in FIG. 14, as another example of the combined operation, when loading the earth and sand scooped up by the bucket 13 onto the loading platform of the dump truck, it is conceivable to operate the slewing motor 6 and the boom cylinder 14 in parallel. Note that the configuration, arrangement, and role of the direction control valve 74, the meter-in control valve 75, the opening amount control valve 76, and the pressure sensors 77 and 78 for supplying and discharging hydraulic oil to and from the slewing motor 6 are common to the direction control valve 23, the meter-in control valve 25, the opening amount control valve 27, and the pressure sensors 32 and 33 described above.

[0099] If the above-described processing is applied to such a combined operation, even when loading the earth and sand scooped up by the bucket 13 onto the dump truck bed, the bucket 13 can be moved along the trajectory intended by the operator, so that contact between the bucket 13 and the dump truck can be prevented.

[0100] The above-described embodiments are examples for explaining the present invention, and are not intended to limit the scope of the present invention only to those embodiments. Those skilled in the art can implement the present invention in various other modes without departing from the gist of the present invention.

Explanation of Reference Numerals

[0101] 1 Hydraulic excavator (working machine) 2 Lower traveling body 3 Upper slewing body 4 Crawler 5 Traveling motor (hydraulic actuator) 6 Slewing motor (hydraulic actuator) 7 Slewing frame 8 Cab 9 Counterweight 10 Front working machine 11 Boom 12 Arm 13 Bucket 14 Boom cylinder (hydraulic actuator) 15 Arm cylinder (hydraulic actuator) 16 Bucket cylinder (hydraulic actuator) 20 Engine (prime mover) 21 Hydraulic oil tank 22 Hydraulic pump (hydraulic pump) 22a Regulator 23, 24 Direction control valve (flow control valve) 25, 26 Meter-in control valve (flow control valve) 27, 28 Opening amount control valve (flow control valve) 29 Relief valve 30 Bleed-off valve 31~35, 77, 78 Pressure sensor 36 - 39 Posture Sensor 41 Boom Operation Lever (Operating Device, Operation Quantity Detection Sensor) 42 Arm Operation Lever (Operating Device, Operation Quantity Detection Sensor) 43 EC Dial (Engine Rotation Speed Setting Device) 50 Controller 51 CPU 52 Memory

Claims

1. A prime mover that generates driving force, a hydraulic pump that discharges pressured oil by the driving force of the prime mover, a discharge pressure sensor that detects the discharge pressure of the hydraulic pump, a plurality of hydraulic actuators that operate by the pressured oil supplied from the hydraulic pump, a plurality of flow control valves that control the supply and discharge amount of pressured oil for each of the plurality of hydraulic actuators, an operating device that operates each of the plurality of hydraulic actuators, an operation amount detection sensor that detects the operation amount by the operating device, and a controller that controls at least one of the prime mover, the hydraulic pump, and the plurality of flow control valves in a working machine comprising: the controller, calculates a pump flow rate limit value of the pressured oil that the hydraulic pump can discharge based on a preset output limit value of the prime mover and the discharge pressure of the hydraulic pump detected by the discharge pressure sensor, calculates the required speed of each of the plurality of hydraulic actuators based on the operation amount detected by the operation amount detection sensor, calculates a pump flow rate estimated value that is an estimated value of the flow rate of the pressured oil that the hydraulic pump should discharge in order to satisfy the calculated plurality of required speeds, calculates a plurality of target speeds by correcting each of the plurality of required speeds based on the ratio of the pump flow rate limit value and the pump flow rate estimated value, controls the prime mover, the hydraulic pump, and the plurality of flow control valves so that each of the plurality of hydraulic actuators operates at the target speed, the flow control valve, is controlled by the controller based on the smaller value of the meter-in opening amount calculated based on the operation amount and the target meter-in opening amount calculated based on the operation amount and the discharge pressure of the hydraulic pump, a working machine characterized by the above.

2. In the working machine according to Claim 1, comprises a plurality of pressure sensors that detect the measured pressure of the pressured oil supplied and discharged to each of the plurality of hydraulic actuators, the controller, calculates the target pressure of the pressured oil supplied and discharged to each of the plurality of hydraulic actuators based on the target speed, controls the opening amount of each of the plurality of flow control valves based on the difference between the target pressure and the measured pressure, a working machine characterized by the above.

3. In the working machine according to Claim 1, the flow control valve, is a direction control valve that controls the supply direction of the pressured oil to the hydraulic actuator, A meter-in control valve that is disposed on a flow path from the hydraulic pump to the direction control valve and controls the flow rate of the pressure oil supplied to the hydraulic actuator through the direction control valve is included, the controller controls at least one of the direction control valve and the meter-in control valve A construction machine characterized by this.

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