Construction machine

Abstract

This construction machine is provided with: a first hydraulic actuator and a second hydraulic actuator which are driven by a first hydraulic pump and a second hydraulic pump, respectively, and which drive a front working machine; a third hydraulic actuator driven by the second hydraulic pump; a solenoid valve for controlling the hydraulic oil flowing to the second hydraulic actuator; an operation device for operating the front working machine; and a controller that controls the solenoid valve, the first hydraulic pump, and the second hydraulic pump on the basis of the distance between the front working machine and a target construction surface and an operation signal, the controller being configured to control the solenoid valve, the first hydraulic pump, and the second hydraulic pump on the basis of the flow rate difference between the maximum read flow rate of the second hydraulic pump and the flow rate supplied to the third hydraulic actuator. And a controller configured to calculate an upper limit speed of the second hydraulic actuator, limit a required speed of the second hydraulic actuator according to the operation signal by the upper limit speed, calculate a target flow rate of the second hydraulic pump, and control the solenoid valve and the second hydraulic pump according to the target speed.

Description

Technical Field

[0001] The present invention relates to engineering machinery such as hydraulic excavators. Background Art

[0002] In recent years, information-based construction has been introduced to construction sites through the use of ICT, and construction machinery with mechanical control (hereinafter referred to as MC) functions has also become popular. The MC is to automatically control or semi-automatically control the front working machine according to the designed terrain (target construction surface) of the construction site. In this application specification, "automatic control" means that the controller drives the hydraulic actuator that the operator is not operating, and "semi-automatic control" means that the controller intervenes in the operator's operation and corrects the action of the hydraulic actuator that the operator is operating.

[0003] However, at the construction site, even when the MC function is being used, the operator may operate a hydraulic actuator other than the hydraulic actuator that is the target of the MC. For example, when driving the front working machine using the MC function, the operator may operate attachments such as the positioning hydraulic cylinder and the tilt rotator, or perform a rotation operation of the rotating body when the machine body cannot be directly facing the construction surface due to the working environment or when the working range is expanded to suppress the number of machine body movements.

[0004] In MC control, the target flow rate for driving the hydraulic actuator according to the target speed of the hydraulic actuator corresponding to the operator's operation is sometimes calculated, and the discharge flow rate of the hydraulic pump and the pilot pressure of the control valve are controlled. When multiple hydraulic actuators are combined, the discharge flow rate of the hydraulic pump is determined according to the target speed and target flow rate of each hydraulic actuator, but the maximum flow rate that the hydraulic pump can discharge is determined according to the specifications of the hydraulic pump. Therefore, when the total target flow rate of the multiple hydraulic actuators driven exceeds the maximum discharge flow rate of the hydraulic pump, sometimes each hydraulic actuator cannot be driven at the target speed. In this case, there is a possibility that the MC control accuracy is reduced and the construction site cannot be formed according to the design, or the fuselage cannot be manually operated according to the operator's intention.

[0005] As a technology to solve this problem, Patent Document 1 discloses a hydraulic control device that, when the maximum discharge flow rate of a hydraulic pump is insufficient for the total target flow rate of a plurality of hydraulic actuators, makes up for the insufficient amount by merging discharge oils from other hydraulic pumps.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2007-100779 Summary of the invention

[0009] Generally, when multiple hydraulic actuators connected to the same hydraulic pump are operated simultaneously, the discharge oil of the hydraulic pump has the characteristic of easily flowing into the hydraulic actuator with a low load pressure. On the other hand, the fewer the flow splits and flows of the oil circuit connecting the hydraulic actuator and the hydraulic pump, the more the influence of the load pressure on the control of the supply flow to each hydraulic actuator can be suppressed. Based on this situation, in MC control, it is desired to reduce the number of hydraulic pumps and hydraulic actuators connected to the same oil circuit to suppress the flow splits and flows of the discharge oil of the hydraulic pump.

[0010] In contrast, in the hydraulic control device described in Patent Document 1, when the maximum discharge flow rate of the hydraulic pump is insufficient for the target flow rate of the hydraulic actuator, the target flow rate of the hydraulic actuator is ensured by converging the discharge oil of other hydraulic pumps. However, in this configuration, the number of locations where the discharge oil of the hydraulic pump is divided and the number of locations where it is merged increases, making it more susceptible to the load pressure of each hydraulic actuator. In addition, the flow division during compound action becomes complicated, and there is a concern that the MC control accuracy may be reduced.

[0011] As an example of an operation using MC control, there is an operation called floor digging work. Floor digging work is a leveling operation of digging the ground in front of the machine body by linking the boom and the arm so that the height of the digging surface becomes uniform. In this case, for example, when the boom hydraulic cylinder is driven by the first hydraulic pump and the arm hydraulic cylinder is driven by the second hydraulic pump, the hydraulic actuator and the hydraulic pump become a one-to-one relationship, there is no diversion and confluence, and the MC control accuracy is ensured to be high. In this ground digging work, sometimes it is desired to expand the leveling range without moving the vehicle body, and the rotation action is operated during the driving of the boom and the arm under MC control. In this case, if the circuit is configured so that the rotation motor is driven by the second hydraulic pump, the discharge oil of the second hydraulic pump will be diverted to the arm hydraulic cylinder and the rotation motor, unlike when the ground digging work is performed only by the action of the boom and the arm. In this situation, when the total target flow of the arm hydraulic cylinder and the rotation motor exceeds the maximum discharge flow of the second hydraulic pump due to the operation of the operator, the maximum discharge flow of the second hydraulic pump is insufficient relative to the target flow. In this example, in the technology described in Patent Document 1, the target flow rates of the boom cylinder and the swing motor can be ensured by merging the discharge oil of the first hydraulic pump with the oil circuit of the second hydraulic pump. However, by merging the discharge oil of the first hydraulic pump and the second hydraulic pump in this way, not only the discharge oil of the second hydraulic pump but also the discharge oil of the first hydraulic pump is divided to the boom cylinder, the boom cylinder and the swing motor. As a result, there is a concern that the load pressure of the first hydraulic pump and the boom cylinder will affect the MC control related to the ground excavation operation, and the MC control accuracy will be reduced.

[0012] An object of the present invention is to provide a construction machine capable of ensuring good responsiveness to an operator's intended operation while suppressing a decrease in MC control accuracy even when a hydraulic actuator that is not an MC control target is operated during MC control.

[0013] In order to achieve the above-mentioned purpose, the present invention provides a construction machinery comprising: a body; a front working machine installed on the body; a first hydraulic pump and a second hydraulic pump mounted on the body; a first hydraulic actuator driven by the discharge oil of the first hydraulic pump and driving the front working machine; a second hydraulic actuator driven by the discharge oil of the second hydraulic pump and driving the front working machine; a third hydraulic actuator driven by the discharge oil of the second hydraulic pump; a direction switching valve for controlling the flow of hydraulic oil from the second hydraulic pump to the second hydraulic actuator; a solenoid valve for generating a pilot pressure for driving the direction switching valve; an operating device for operating the front working machine; a sensor for detecting a state quantity corresponding to the action of the third hydraulic actuator; and a controller for controlling the solenoid valve and the first hydraulic pump and the second hydraulic pump based on a distance between a specific point of the front working machine and a preset target construction surface, i.e., a target surface distance, and an operating signal corresponding to the operation of the operating device. The controller is configured to calculate the supply flow rate of the hydraulic oil from the second hydraulic pump to the third hydraulic actuator based on the output of the sensor, calculate the upper limit speed of the second hydraulic actuator based on the flow difference between the maximum flow rate that the second hydraulic pump can discharge and the supply flow rate to the third hydraulic actuator, compare the required speed of the second hydraulic actuator corresponding to the operation signal with the upper limit speed, calculate the required speed as the target speed of the second hydraulic actuator when the required speed is below the upper limit speed, calculate the upper limit speed as the target speed when the required speed exceeds the upper limit speed, calculate the target flow rate of the second hydraulic pump by adding the supply flow rate to the third hydraulic actuator to the flow rate corresponding to the target speed of the second hydraulic actuator, control the solenoid valve based on the target speed, and control the second hydraulic pump based on the target flow rate.

[0014] Effects of the Invention

[0015] According to the present invention, there is provided a construction machine capable of ensuring good responsiveness to an operator's intended manual operation while suppressing a decrease in MC control accuracy even when a hydraulic actuator not subject to MC control is manually operated during MC control. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a side view of a hydraulic excavator which is an example of a construction machine according to the first embodiment of the present invention.

[0017] Figure 2 This is a hydraulic circuit diagram of a main part of a hydraulic system mounted on a construction machine according to a first embodiment of the present invention.

[0018] Figure 3 This is a schematic diagram showing the logic of MC control performed by the controller included in the construction machine according to the first embodiment of the present invention.

[0019] Figure 4 is a diagram showing a target speed calculation ( Figure 3 ) is a functional block diagram of the detailed processing.

[0020] Figure 5 The pump flow rate calculation ( Figure 3 ) is a functional block diagram of the detailed processing.

[0021] Figure 6 This is a diagram showing an example of changes in the target flow rate of the second hydraulic pump and the target flow rate of the arm hydraulic cylinder occupied therein when the swing operation intervenes in the MC control in the first embodiment of the present invention.

[0022] Figure 7 This is a schematic diagram showing the logic of MC control performed by a controller included in a construction machine according to a second embodiment of the present invention.

[0023] Figure 8 is a diagram showing a target speed calculation ( Figure 7 ) is a functional block diagram of the detailed processing.

[0024] Fig. 9 This is a functional block diagram showing detailed processing of target speed calculation by a controller included in a construction machine according to a third embodiment of the present invention.

[0025] Fig.10 This is a diagram showing an example in which the difference between the target speed and the estimated actual speed of the second hydraulic actuator increases rapidly in a short period of time. DETAILED DESCRIPTION

[0026] Hereinafter, embodiments of the present invention will be described using the drawings.

[0027] (First embodiment)

[0028] 1. Construction machinery

[0029] Figure 1 1 is a side view of a hydraulic excavator as an example of a construction machine according to the first embodiment of the present invention. In the present embodiment, a hydraulic excavator having a bucket 23 installed as an attachment at the front end of a front working machine 20 (working device) is described as an example of a construction machine. However, the present invention can also be applied to a hydraulic excavator having attachments other than a bucket installed, or other types of construction machines such as a wheel loader and a bulldozer. In this application specification, the front of the cab 16 ( Figure 1 The right side in the figure) is set to be the front of the hydraulic excavator (strictly speaking, the rotating body 12).

[0030] The hydraulic excavator shown in the figure includes a vehicle body 10 and a front working device 20 mounted on the vehicle body 10 . The vehicle body 10 includes a traveling body 11 and a revolving body 12 .

[0031] In the present embodiment, the traveling body 11 includes left and right crawler-type traveling devices 13 having endless track crawlers, and travels by driving the left and right traveling devices 13 respectively by left and right traveling motors 14. As the traveling motors 14, hydraulic motors are used.

[0032] The rotating body 12 is rotatably provided on the upper part of the traveling body 11 via a rotating device 15. The rotating device 15 connecting the traveling body 11 and the rotating body 12 includes a rotating motor 34, which is driven to rotate the rotating body 12 around a vertical center axis relative to the traveling body 11. The rotating motor 34 is a hydraulic actuator (hydraulic motor). A cab 16 for an operator to ride is provided at the front part of the rotating body 12 (in this embodiment, the front left side). On the rear side of the cab 16 in the rotating body 12, a hydraulic pump P1, P2 ( Figure 2 ) etc., and a counterweight 18 is mounted at the rear end to achieve weight balance with the front working machine 20.

[0033] The front working machine 20 is a multi-jointed working arm used for performing operations such as excavation of earth and sand, and is connected to the front part of the rotating body 12 (in the present embodiment, the right side of the cab 16). The front working machine 20 is composed of a boom 21, an arm 22, and a bucket 23. The boom 21 is connected to the base frame of the rotating body 12, that is, the rotating frame 19, by a pin, and rotates up and down relative to the rotating body 12 as the boom hydraulic cylinder 31 is extended or retracted. Both ends of the boom hydraulic cylinder 31 are rotatably connected to the boom 21 and the rotating body 12. The arm 22 is connected to the front end of the boom 21 by a pin, and rotates forward and backward relative to the boom 21 as the arm hydraulic cylinder 32 is extended or retracted. Both ends of the arm hydraulic cylinder 32 are rotatably connected to the arm 22 and the boom 21. The bucket 23 is connected to the front end of the arm 22 by a pin, and rotates relative to the arm 22 as the bucket hydraulic cylinder 33 is extended or retracted. The base end of the bucket cylinder 33 is connected to the arm 22, and the front end is connected to the bucket 23 via a link. The boom cylinder 31, the arm cylinder 32, and the bucket cylinder 33 that drive the front working machine 20 are hydraulic actuators.

[0034] In addition, angle detectors D1 to D3 are provided at the respective rotation fulcrums of the boom 21, the arm 22, and the bucket 23, and an angle detector D4 is provided at the rotation device 15 of the rotating body 12. The angle detector D1 is a detector that detects a state quantity corresponding to the motion of the boom 21, which is a driven component driven by the boom hydraulic cylinder 31. In this embodiment, the rotation angle of the boom 21 relative to the rotating frame 19 is detected and output to the controller 50. The angle detector D2 is a detector that detects a state quantity corresponding to the motion of the arm 22, which is a driven component driven by the arm hydraulic cylinder 32. In this embodiment, the rotation angle of the arm 22 relative to the boom 21 is detected and output to the controller 50. The angle detector D3 is a detector that detects a state quantity corresponding to the motion of the bucket 23, which is a driven component driven by the bucket hydraulic cylinder 33. In this embodiment, the rotation angle of the bucket 23 relative to the arm 22 is detected and output to the controller 50. The angle detector D4 is a detector that detects a state quantity corresponding to the movement of the driven component driven by the rotary motor 34, that is, the rotary body 12. In the present embodiment, the rotation angle of the rotary body 12 relative to the travel body 11 is detected and output to the controller 50. In the MC control, the posture of the front working machine 20 is calculated based on the output (detection signal) of the angle detectors D1-D4. In addition, the rotation speed of the rotary body 12 is calculated based on the output (detection signal) of the angle detector D4. The angle detectors D1-D4 are examples of detectors that detect the movement of the driven components (boom 21, arm 22, bucket 23, rotary body 12) driven by the corresponding hydraulic actuators. The time variation of each rotation angle detected by the angle detectors D1-D4 is an example of a state quantity corresponding to the variation and the movement of the corresponding hydraulic actuator.

[0035] 2. Hydraulic system

[0036] Figure 2 yes Figure 1 A hydraulic circuit diagram showing the main parts of the hydraulic system on a hydraulic excavator. Figure 2 In FIG. 1 , the circuits for driving the boom hydraulic cylinder 31 , the arm hydraulic cylinder 32 , the bucket hydraulic cylinder 33 , and the swing motor 34 are extracted and shown.

[0037] Figure 2 The hydraulic system shown has a plurality of (two in this embodiment) hydraulic pumps P1 and P2, a pilot pump P3, a directional control valve Vn, solenoid valves Sn1 and Sn2, an operating device Ln, and a controller 50. N is a natural number from 1 to 4 (n=1, 2, 3, 4).

[0038] 2-1. Hydraulic pump

[0039] The hydraulic pumps P1 and P2 are hydraulic sources for various hydraulic actuators mounted on the hydraulic excavator, such as the boom hydraulic cylinder 31, the arm hydraulic cylinder 32, the bucket hydraulic cylinder 33, and the swing motor 34, and are mounted on the vehicle body 10 (machine room 17) together with the prime mover E. The hydraulic pumps P1 and P2 are driven by the prime mover E, suck the hydraulic oil in the hydraulic oil tank T to increase its pressure, and discharge the hydraulic oil for driving the corresponding hydraulic actuator. Figure 2 In FIG. 1 , an engine (internal combustion engine) is shown as the prime mover E, but an electric motor may be used as the prime mover E. The hydraulic pumps P1 and P2 are variable displacement pumps whose capacities are controlled by pump regulators R1 and R2 , respectively. Figure 2 Although a hydraulic system including two hydraulic pumps P1 and P2 is exemplified in the embodiment, there is also a case where the hydraulic system includes three or more hydraulic pumps.

[0040] The hydraulic oil discharged from the hydraulic pump P1 flows in the pump line PL1 as the discharge oil path of the hydraulic pump P1, and is supplied to the boom cylinder 31 and the bucket cylinder 33 via the direction switching valves V1 and V3. In response to this, the return oil discharged from the boom cylinder 31 and the bucket cylinder 33 flows into the tank line TL via the direction switching valves V1 and V3 and flows back to the hydraulic oil tank T. Although not shown in the figure, the pump line PL1 and the tank line TL are connected via a relief valve that limits the maximum pressure of the pump line PL1.

[0041] Similarly, the hydraulic oil discharged from the hydraulic pump P2 flows in the pump line PL2 which is the discharge oil path of the hydraulic pump P2, and is supplied to the boom cylinder 32 and the swing motor 34 via the direction switching valves V2 and V4. In response to this, the return oil discharged from the boom cylinder 32 and the swing motor 34 flows into the tank line TL via the direction switching valves V2 and V4 and flows back to the working oil tank T. Although not shown in the figure, the pump line PL2 and the tank line TL are connected via a relief valve which limits the maximum pressure of the pump line PL2.

[0042] In the hydraulic system of this embodiment, the pump lines PL1 and PL2 are independent of each other, and the hydraulic oil flowing in the pump lines PL1 and PL2 is not configured to converge and be supplied to the hydraulic actuator. In other words, there is no oil circuit that bypasses the boom hydraulic cylinder 31, the arm hydraulic cylinder 32, the bucket hydraulic cylinder 33, and the swing motor 34 and directly connects the pump lines PL1 and PL2. However, although it is desirable that the pump lines PL1 and PL2 are independent, it is also possible to configure the pump lines PL1 and PL2 to be connected and the discharge oil of the hydraulic pumps P1 and P2 to converge and be supplied to the same hydraulic actuator.

[0043] 2-2. Pilot pump

[0044] The pilot pump P3 is a fixed displacement pump that outputs a primary pressure (initial pressure) of a pilot pressure for driving a hydraulically driven control valve, such as a directional switching valve Vn, included in the hydraulic system. The pilot pump P3 is driven by a prime mover E in the same manner as the hydraulic pumps P1 and P2. However, the pilot pump P3 may be driven by a power source different from the prime mover E.

[0045] 2-3. Directional switching valve

[0046] The direction switching valves Vn (n=1, 2, 3, 4) control the flow (direction and flow rate) of the hydraulic oil supplied to the boom cylinder 31 , the arm cylinder 32 , the bucket cylinder 33 , and the swing motor 34 .

[0047] The direction switching valve V1 is used for boom driving. The pilot pressure input to its pilot oil chamber and the restoring force of the spring drive the slide valve to control the supply, discharge and stop of the hydraulic oil to the boom hydraulic cylinder 31. In addition to the pump line PL1 and the tank line TL of the hydraulic pump P1, the cylinder bottom side oil chamber and the piston rod side oil chamber of the boom hydraulic cylinder 31 are also connected to each port of the direction switching valve V1. If the pump line PL1 is connected to the cylinder bottom side oil chamber through the direction switching valve V1, the boom hydraulic cylinder 31 extends and the boom 21 performs a boom lifting action. On the contrary, if the pump line PL1 is connected to the piston rod side oil chamber through the direction switching valve V1, the boom hydraulic cylinder 31 contracts and the boom 21 performs a boom lowering action. When no pilot pressure acts on the pilot oil chamber, the spool of the direction switching valve V1 is in a neutral position due to the restoring force of the spring, and the boom cylinder 31 is disconnected from the pump line PL1 and the tank line TL, whereby the boom cylinder 31 stops.

[0048] Similar to the direction switching valve V1 for the boom cylinder 31 , the direction switching valve V2 for the arm cylinder 32 , the direction switching valve V3 for the bucket cylinder 33 , and the direction switching valve V4 for the swing motor 34 are also driven by the pilot pressure and the restoring force of the spring.

[0049] The pump line PL1 of the hydraulic pump P1, the tank line TL, the cylinder bottom side oil chamber and the piston rod side oil chamber of the bucket hydraulic cylinder 33 are connected to each port of the direction switching valve V3 for driving the bucket. When the pump line PL1 is connected to the cylinder bottom side oil chamber of the bucket hydraulic cylinder 33 through the direction switching valve V3, the bucket hydraulic cylinder 33 is extended to load the bucket 23. On the contrary, when the pump line PL1 is connected to the piston rod side oil chamber of the bucket hydraulic cylinder 33 through the direction switching valve V3, the bucket hydraulic cylinder 33 is retracted to unload the bucket 23. When the direction switching valve V3 is returned to the neutral position, the bucket hydraulic cylinder 33 stops.

[0050] The pump line PL2 of the hydraulic pump P2, the tank line TL, the cylinder bottom oil chamber and the piston rod side oil chamber of the boom hydraulic cylinder 32 are connected to each port of the direction switching valve V2 for boom driving. If the pump line PL2 is connected to the cylinder bottom oil chamber of the boom hydraulic cylinder 32 through the direction switching valve V2, the boom hydraulic cylinder 32 extends and the boom 22 is retracted. On the contrary, if the pump line PL2 is connected to the piston rod side oil chamber of the boom hydraulic cylinder 32 through the direction switching valve V2, the boom hydraulic cylinder 32 contracts and the boom 22 is released. If the direction switching valve V2 returns to the neutral position, the boom hydraulic cylinder 32 stops.

[0051] The pump line PL2 of the hydraulic pump P2, the tank line TL, one port and the other port of the rotary motor 34 are connected to the respective ports of the direction switching valve V4 for rotary drive. When the pump line PL2 is connected to one port of the rotary motor 34 through the direction switching valve V4, the rotary motor 34 rotates forward to rotate the rotary body 12 to one side in the left-right direction. On the contrary, when the pump line PL2 is connected to the other port of the rotary motor 34 through the direction switching valve V4, the rotary motor 34 rotates reversely to rotate the rotary body 12 to the other side in the left-right direction. When the direction switching valve V4 returns to the neutral position, the rotary motor 34 stops.

[0052] 2-5. Solenoid valve

[0053] The solenoid valves Sn1 and Sn2 (n=1, 2, 3, 4) are electromagnetically driven proportional pressure reducing valves that generate pilot pressure for driving the directional switching valves Vn (n=1, 2, 3, 4). The solenoid valves Sn1 and Sn2 are connected to the pilot primary pressure pipeline PL3, which is the discharge oil path of the pilot pump P3. The solenoid valves Sn1 and Sn2 are driven by a command signal from the controller 50, and reduce the pressure of the pilot primary pressure pipeline PL3 to generate a pilot pressure (pilot secondary pressure).

[0054] The solenoid valves S11 and S12 generate a pilot pressure for driving the direction switching valve V1 for driving the boom and output it to the pilot oil chamber of the direction switching valve V1. The solenoid valve S11 is used for the boom raising action. If the pilot pressure output by the solenoid valve S11 is input to the direction switching valve V1, the discharge oil of the hydraulic pump P1 is supplied to the cylinder bottom side oil chamber of the boom hydraulic cylinder 31 to extend the boom hydraulic cylinder 31. The solenoid valve S12 is used for the boom lowering action. If the pilot pressure output by the solenoid valve S12 is input to the direction switching valve V1, the discharge oil of the hydraulic pump P1 is supplied to the piston rod side oil chamber of the boom hydraulic cylinder 31 to retract the boom hydraulic cylinder 31.

[0055] The solenoid valves S21 and S22 generate a pilot pressure for driving the direction switching valve V2 for driving the boom and output it to the pilot oil chamber of the direction switching valve V2. The solenoid valve S21 is used for the boom retracting action. If the pilot pressure output by the solenoid valve S21 is input to the direction switching valve V2, the discharge oil of the hydraulic pump P2 is supplied to the cylinder bottom side oil chamber of the boom hydraulic cylinder 32 to extend the boom hydraulic cylinder 32. The solenoid valve S22 is used for the boom releasing action. If the pilot pressure output by the solenoid valve S22 is input to the direction switching valve V2, the discharge oil of the hydraulic pump P2 is supplied to the piston rod side oil chamber of the boom hydraulic cylinder 32 to retract the boom hydraulic cylinder 32.

[0056] The solenoid valves S31 and S32 generate a pilot pressure for driving the direction switching valve V3 for driving the bucket and output it to the pilot oil chamber of the direction switching valve V3. The solenoid valve S31 is used for bucket loading. If the pilot pressure output by the solenoid valve S31 is input to the direction switching valve V3, the discharge oil of the hydraulic pump P1 is supplied to the cylinder bottom side oil chamber of the bucket hydraulic cylinder 33 to extend the bucket hydraulic cylinder 33. The solenoid valve S32 is used for bucket unloading. If the pilot pressure output by the solenoid valve S32 is input to the direction switching valve V3, the discharge oil of the hydraulic pump P1 is supplied to the piston rod side oil chamber of the bucket hydraulic cylinder 33 to retract the bucket hydraulic cylinder 33.

[0057] The solenoid valves S41 and S42 generate a pilot pressure for driving the direction switching valve V4 for rotational drive and output it to the pilot oil chamber of the direction switching valve V4. The solenoid valve S41 is for left rotation. If the pilot pressure output by the solenoid valve S41 is input to the direction switching valve V4, the discharge oil of the hydraulic pump P2 is supplied to one side port of the rotation motor 34 to make the rotation motor 34 rotate forward. The solenoid valve S42 is for right rotation. If the pilot pressure output by the solenoid valve S42 is input to the direction switching valve V4, the discharge oil of the hydraulic pump P2 is supplied to the other side port of the rotation motor 34 to make the rotation motor 34 reverse.

[0058] In addition, the pilot pressures outputted from the solenoid valves Sn1 and Sn2 are respectively detected by pressure sensors Ps and inputted to the controller 50 .

[0059] 2-6. Operating device

[0060] The operating devices L1-L4 are operating lever devices (electric lever devices in the present embodiment) that respectively operate the direction switching valves V1-V4 and thereby operate the corresponding hydraulic actuators, and are arranged in the interior of the cab 16. The operating device L1 is an operating lever device for boom operation that operates the boom hydraulic cylinder 31. The operating device L2 is an operating lever device for boom operation that operates the dipper hydraulic cylinder 32. The operating device L3 is an operating lever device for bucket operation that operates the bucket hydraulic cylinder 33. The operating device L4 is an operating lever device for rotation operation that operates the rotation motor 34.

[0061] The operating devices L1-L4 share two operating levers. For example, the operating devices L1 and L3 share one operating lever, which is arranged on the right side of the driver's seat (not shown). If the operating lever is tilted to the left or right, the bucket 23 will move, and if it is tilted forward or backward, the boom 21 will move. In addition, the operating devices L2 and L4 share one operating lever, which is arranged on the left side of the driver's seat (not shown). If the operating lever is tilted to the left or right, the arm 22 will move, and if it is tilted forward or backward, the rotating body 12 will rotate. The correspondence between the operating direction of such an operating lever and the hydraulic actuator can be appropriately changed. The operating devices L1-L4 have sensors such as potentiometers that detect the lever operation amount and output it to the controller 50. The lever operation amount of each operating device L1-L4 detected by these sensors is an example of a state quantity corresponding to the change amount and the action of the corresponding hydraulic actuator.

[0062] 3. Controller

[0063] The controller 50 is a vehicle-mounted computer mounted on the vehicle body 10, and has a function of controlling the hydraulic actuators that drive the front working machine 20, in this embodiment, the boom hydraulic cylinder 31 and the arm hydraulic cylinder 32. The controller 50 has a computing device 51, a storage device 52, and a signal input and output port. The computing device 51 executes various computing processes of the MC control computing unit 53 and the MC control correction unit 54, and outputs control signals to the solenoid valves Sn1, Sn2 and the pump regulators R1, R2. The storage device 52 stores data of the target construction surface of the work site set in advance by the operator, for example. The MC control computing unit 53 and the MC control correction unit 54 have functions executed by the controller 50 (computing device 51), and can be virtually realized by software or by hardware such as an electronic circuit. The controller 50 is input with the outputs (detection signals, operation signals) of the angle detectors D1-D4, the operating devices L1-L4, and the pressure sensors Ps.

[0064] In this embodiment, the MC control operation unit 53 performs linkage control (MC control) on the boom hydraulic cylinder 31 and the dipper arm hydraulic cylinder 32, for example, by controlling the solenoid valves S11, S12, S21, and S22, based on the distance between a specific point of the front working machine 20 (typically, the claw tip of the bucket 23) and a preset target construction surface, i.e., the target surface distance, and the operation signal related to the operation of the operating device L2. In addition, although the description is omitted, the hydraulic excavator is equipped with a GNSS mobile station that obtains data on the position and orientation of the vehicle body 10, and a posture sensor that detects the posture (tilt angle to the front, back, left, and right) of the vehicle body 10. In the MC control operation unit 53, the target surface distance is usually calculated based on data such as the position, orientation, and posture of the vehicle body 10 relative to the target construction surface.

[0065] In addition, in the present embodiment, the hydraulic pump P1 is the first hydraulic pump, the hydraulic pump P2 is the second hydraulic pump, the boom hydraulic cylinder 31 is the first hydraulic actuator as the MC control object, and the arm hydraulic cylinder 32 is the second hydraulic actuator as the MC control object. The swing motor 34 is the third hydraulic actuator as the non-MC control object. For example, when the MC control function is set to be effective, when the target surface distance is less than the set value, if the arm retraction operation is performed, the controller 50 controls the pump regulators R1 and R2 and the solenoid valves S11, S12, and S21 so that the claw tip of the bucket 23 moves along the target construction surface and digs the ground surface, and the boom 21 and the arm 22 are linked to each other. However, even in the process of the MC control function being in effect, manual intervention operation of the bucket hydraulic cylinder 33 and the swing motor 34 can be performed.

[0066] When a hydraulic actuator that is not the target of MC control is operated (i.e., manual operation is combined with MC control) during the functioning of MC control, and the number of hydraulic actuators to which hydraulic oil is simultaneously supplied from the same hydraulic pump increases, the MC control correction unit 54 corrects the target speed of the hydraulic actuator related to MC control. As a specific example, when a swing operation intervenes in the MC control related to the linkage of the boom 21 and the arm 22, the supply flow rate of hydraulic oil to the swing motor 34 is calculated based on the output of the angle detector D4, and when it is determined that the MC control is affected (the required flow rate of the arm cylinder 32 cannot be supplied by the hydraulic pump P2), the target speed of the arm cylinder 32 that shares the hydraulic source with the swing motor 34 is corrected. The correction referred to herein means correcting the target speed of the arm cylinder 32 from the value corresponding to the arm operation to a decreasing direction so that the target flow rate of the arm cylinder 32 does not exceed the flow rate obtained by subtracting the supply flow rate to the swing motor 34 from the maximum flow rate that can be discharged by the hydraulic pump P2.

[0067] Next, a specific example of the control logic performed by the MC control calculation unit 53 and the MC control correction unit 54 of the controller 50 will be described.

[0068] 3-1.MC control

[0069] Figure 3 It is a schematic diagram showing the logic of MC control performed by the controller 50 in the first embodiment. Figure 3 exemplifies an algorithm of MC control in which, when the arm 22 is operated by the operating device L2, the boom 21 also moves in conjunction with the arm 22, and the tip of the bucket 23 moves along the target construction surface.

[0070] Figure 3 In the example, the controller 50 repeatedly executes a series of processes such as rotation speed calculation 61, rotation flow rate calculation 62, target speed calculation 63, target flow rate calculation 64, and pump flow rate calculation 65 in a short cycle (eg, 0.1 s) while the MC control function is enabled.

[0071] 3-2. MC control calculation unit (basic processing)

[0072] As a basic process related to MC control (corresponding to the process content of the MC control calculation unit 53), first, the controller 50 calculates the target speed v2 of the boom cylinder 32 (the second hydraulic actuator) based on the operation signal (the amount of boom operation) of the operating device L2, and calculates the target speed v1 of the boom cylinder 31 (the first hydraulic actuator) based on the target speed v2 of the boom cylinder 32, the position and orientation, posture, and target surface distance of the vehicle body 10 (target speed calculation 63). In addition, the controller 50 calculates the opening command values ​​of the direction switching valves V1 and V2 corresponding to the target speeds v1 and v2 using, for example, a conversion table, and outputs the command signals corresponding to the opening command values ​​to the corresponding solenoid valves to control the direction switching valves V1 and V2.

[0073] At the same time, the controller 50 calculates the target flow rate Q1 of the hydraulic oil supplied to the boom hydraulic cylinder 31 (first hydraulic actuator) based on the target speed v1, and calculates the target flow rate Q2 of the hydraulic oil supplied to the dipper arm hydraulic cylinder 32 (second hydraulic actuator) based on the target speed v2 (target flow rate calculation 64). In addition, the controller 50 calculates the total flow rate of the target flow rate Q1 related to the boom drive and the target flow rate related to the bucket drive as the target flow rate Qp1 of the hydraulic pump P1, and outputs a pump control instruction corresponding to the target flow rate Qp1 to control the hydraulic pump P1 (first hydraulic pump) (pump flow rate calculation 65). In the absence of the intervention of the bucket operation, the target flow rate Qp1 is equivalent to the target flow rate Q1 related to the boom drive. In addition, the controller 50 calculates the total flow rate of the target flow rate Q2 related to the dipper arm drive and the target flow rate related to the rotation drive as the target flow rate Qp2, and outputs a pump control instruction corresponding to the target flow rate Qp2 to control the hydraulic pump P2 (second hydraulic pump) (pump flow rate calculation 65). When there is no intervention of the rotation operation, the target flow rate Qp2 corresponds to the target flow rate Q2 related to the arm drive.

[0074] As a result of executing the processing of the MC control calculation unit 53 as described above, the boom cylinder 31 (first hydraulic actuator) and the arm cylinder 32 (second hydraulic actuator) are controlled in conjunction with each other.

[0075] 3-3. MC control correction unit (correction processing)

[0076] In addition, in the above-mentioned processing of the MC control calculation unit 53, a correction processing of the target speeds v1 and v2 (processing of the MC control correction unit 54) is incorporated, and the rotation operation and bucket operation performed in combination with the MC control are additionally considered for the target speeds v1 and v2. Specifically, when the maximum discharge flow rate Qmax of each hydraulic pump P1 and P2 becomes insufficient relative to the total required flow rate of the hydraulic actuators in charge, the target speeds v1 and v2 of the hydraulic actuators related to the MC control are limited. The processing of the MC control correction unit 54 is described below by taking the case where the rotation operation intervenes in the MC control involving the linkage control of the boom 21 and the dipper arm 22 corresponding to the target construction surface as an example.

[0077] In the correction process related to the MC control correction unit 54, the controller 50 first calculates the rotation speed v3 of the rotating body 12 based on the output of the angle detector D4 (sensor) (rotation speed calculation 61), and calculates the supply flow rate Q3 of the hydraulic oil from the hydraulic pump P2 (second hydraulic pump) to the rotating motor 34 (third hydraulic actuator) based on the rotation speed v3 (rotation flow rate calculation 62). Assuming that a rotation operation is performed by the operating device L4, the rotating body 12 rotates according to the rotation operation signal, and the rotation speed v3 and the supply flow rate Q3 whose absolute values ​​are greater than 0 are calculated. If the operating device L4 is not operated and the rotating body 12 stops, the calculation results of the rotation speed v3 and the supply flow rate Q3 are 0.

[0078] The supply flow rate Q3 to the swing motor 34 (third hydraulic actuator) calculated by the swing flow rate calculation 62 is reflected in the calculation of the target speeds v1 and v2 in the target speed calculation 63 and in the control of the hydraulic pumps P1 and P2 in the pump flow rate calculation 65. Specifically, in the target speed calculation 63, the supply flow rate Q3 is reflected in the target speed v2 of the boom cylinder 32 and also in the target speed v1 of the boom cylinder 31 corresponding to the target speed v2. As a result, when the swing operation by the operator is compounded in the MC control, the control command values ​​to the solenoid valve and the hydraulic pump change.

[0079] Figure 4 Yes means Figure 3 A functional block diagram of the detailed processing of the target speed calculation 63 is shown.

[0080] In the process of the target speed calculation 63, first, the controller 50 calculates the flow difference Qd by subtracting the supply flow Q3 (rotation flow) to the rotation motor 34 from the maximum flow Qmax that can be discharged by the hydraulic pump P2 (the second hydraulic pump) (processing 63a). The flow difference Qd is equivalent to the maximum flow that can be supplied to the boom cylinder 32 by the hydraulic pump P2 alone in a manner that does not allow the discharge oil of the hydraulic pump P1 to merge with the discharge oil of the hydraulic pump P2. Next, the controller 50 calculates the upper limit speed v2u of the boom cylinder 32 (the second hydraulic actuator) that can be achieved by the flow difference Qd based on the flow difference Qd (processing 63b). Simultaneously with the calculation of the upper limit speed v2u, the controller 50 calculates the required speed v2r (arm required speed) of the boom cylinder 32 (the second hydraulic actuator) corresponding to the operation signal (arm operation amount) of the operating device L2 related to the boom operation (processing 63c).

[0081] Furthermore, the controller 50 compares the required speed v2r and the upper limit speed v2u of the boom cylinder 32, and calculates the target speed v2 (bucket arm target speed) of the boom cylinder 32 (second hydraulic actuator) by selecting the minimum value (processing 63d). The target speed v2 is not limited to a value corresponding to the boom operation amount (bucket arm required speed), and can also be corrected according to the rotation action (action of the third hydraulic actuator). Specifically, when the required speed v2r is below the upper limit speed v2u, the required speed v2r is calculated and used as the target speed v2, and when the required speed v2r exceeds the upper limit speed v2u, the upper limit speed v2u is calculated and used as the target speed v2. That is, the target speed v2 of the boom cylinder 32 is limited by the upper limit speed v2u. In other words, the target speed v2 of the boom cylinder 32 is limited by the following flow rate, which is the flow rate that can be supplied from the hydraulic pump P2 to the boom cylinder 32 on the basis of ensuring the supply flow rate Q3 to the rotation motor 34 corresponding to the rotation operation.

[0082] After calculating the target speed v2 in this way, the controller 50 calculates the target speed v1 (hereinafter, target speed v1) of the boom cylinder 31 based on the target speed v2 of the arm cylinder 32 and, for example, the vehicle body posture and the target surface distance (processing 63e).

[0083] If Figure 3 As described above, the target speeds v1 and v2 are used for calculation of the command values ​​of the solenoid valves and the target flow rates Q1 and Q2 of the boom cylinder 31 and the arm cylinder 32 .

[0084] Figure 5 Yes means Figure 3 A functional block diagram of the detailed processing of the pump flow rate calculation 65 is shown.

[0085] In the process of pump flow calculation 65, first, the controller 50 adds the supply flow Q3 (rotation flow) to the rotation motor 34 (third hydraulic actuator) to the target flow Q2 (bucket arm retraction target flow or bucket arm release target flow) corresponding to the target speed v2 of the boom hydraulic cylinder 32 (second hydraulic actuator), and calculates the target flow Qp2 of the hydraulic pump P2 (second hydraulic pump) (processing 65a). After calculating the target flow Qp2, the controller 50 converts the target flow Qp2 into a control instruction value, for example, through a conversion table, and outputs the control instruction value (second hydraulic pump control instruction) based on the target flow Qp2 to control the hydraulic pump P2 (second hydraulic pump) (processing 65c). In addition, Figure 5Although not shown in the figure, the hydraulic pump P1 (first hydraulic pump) is also controlled in accordance with the target flow rate Qp1 in the same manner. In parallel with this, the controller 50 converts the target speeds v1 and v2 into control command values, outputs the control command values ​​based on the target speeds v1 and v2, and controls the solenoid valve S11 or S12, and the solenoid valve S21 or S22 ( Figure 3 ).

[0086] In addition, since the maximum and minimum values ​​of the flow rate that can be discharged by the hydraulic pump P2 are predetermined based on the specifications of the hydraulic pump P2, the maximum value of the target flow rate Qp2 input to processing 65c is limited by the maximum discharge flow rate Qmax of the hydraulic pump P2 (the maximum flow rate of the second hydraulic pump), and the minimum value of the target flow rate Qp2 is limited by the minimum flow rate Qmin of the hydraulic pump P2 (the minimum flow rate of the second hydraulic pump) (processing 65b).

[0087] Through the above processing, along with the manual intervention operation in the MC control, the control command values ​​for the solenoid valve and the hydraulic pumps P1 and P2 related to the MC control are corrected, and the action related to the manual intervention operation (rotation in the above example) is performed according to the operator's operation. On this basis, the MC control is executed in parallel. For this MC control, it is determined whether the flow rate supplied to the third hydraulic actuator related to the intervention operation can be supplied to the second hydraulic actuator related to the MC control as required, even if the flow rate supplied to the third hydraulic actuator related to the intervention operation is subtracted. If there is no shortage, the target speed of the second hydraulic actuator is output as required. If there is a shortage, the target speed of the second hydraulic actuator is limited and corrected.

[0088] Therefore, when manual operation such as a swivel operation is not involved in the MC control (or even if there is an intervention operation, the total required flow rate is within the maximum discharge flow rate Qmax of the hydraulic pump), the target speeds of the first hydraulic actuator and the second hydraulic actuator related to the MC control will not be affected. As a result of the intervention of manual operation such as a swivel operation in the MC control, for example, the target speed of the arm hydraulic cylinder 32 (the second hydraulic actuator) is corrected, and the target speed of the boom hydraulic cylinder 31 (the first hydraulic actuator) is also calculated based on the target speed of the arm hydraulic cylinder 32, thereby, the trajectory of the bucket 23 does not change and the MC control accuracy is not affected.

[0089] Figure 6This is a diagram showing an example of the transition of the target flow rate Qp2 of the hydraulic pump P2 and the target flow rate Q2 of the boom cylinder 32 occupied therein when the rotation operation intervenes in the MC control in the present embodiment. As shown in the figure, in the MC control, in the state where there is no compound rotation operation, the supply flow rate Q3 to the rotation motor 34 is 0, and the discharge oil of the hydraulic pump P2 can be supplied to the boom cylinder 32 in its entirety, thereby the target flow rate Qp2 of the hydraulic pump P2 is equivalent to the target flow rate Q2 of the boom cylinder 32. However, thereafter, in the case where the rotation operation is compounded in the MC control and the supply flow rate Q3 to the rotation motor 34 is generated, if the supply flow rate Q3 is simply added to the target flow rate Q2 of the boom cylinder 32, the total flow rate will exceed the maximum discharge flow rate Qmax of the hydraulic pump P2, and there is a possibility that the actual boom speed cannot follow the control command value. In addition, there is a possibility that the rotation operation cannot reach the speed corresponding to the operator's operation.

[0090] In contrast, in the present embodiment, even if the supply flow rate Q3 to the rotation motor 34 is generated and increased, by correcting the target speed of the boom hydraulic cylinder 32, the target flow rate Q2 of the boom hydraulic cylinder 32 can be limited to the difference between the maximum discharge flow rate Qmax and the supply flow rate Q3 so that the total flow rate together with the supply flow rate Q3 to the rotation motor 34 does not exceed the maximum discharge flow rate Qmax of the hydraulic pump P2. Therefore, the actual speed of the boom 22 can be matched with the control command value while ensuring the rotation action corresponding to the operator's operation.

[0091] -Effect-

[0092] In the present embodiment, when a hydraulic actuator (e.g., the swing motor 34) that is not an MC control target is combined by manual operation during MC control, even if the total required flow rate of the manually operated hydraulic actuator and the hydraulic actuator (e.g., the boom cylinder 32) connected to the same oil circuit as the hydraulic actuator exceeds the maximum discharge flow rate of the corresponding hydraulic pump (e.g., the hydraulic pump P2), the flow rate that can be used by MC control is limited by the flow difference Qd obtained by subtracting the required flow rate of the manually operated hydraulic actuator from the maximum discharge flow rate. As a result, the target speed of the hydraulic actuator (e.g., the boom cylinder 32) that performs MC control is appropriately corrected, and the flow rate of the hydraulic actuator that performs MC control and the flow rate of the manually operated hydraulic actuator can be determined within the range of the maximum discharge flow rate Qmax of the hydraulic pump at all times. Therefore, the MC control accuracy is not reduced by increasing the flow division and confluence of the oil circuit by, for example, merging the discharge oil of the hydraulic pump P1 with the discharge oil of the hydraulic pump P2. In addition, when the total required flow rate of each hydraulic actuator reaches the maximum discharge flow rate of the hydraulic pump, it is possible to avoid a state where the flow rate cannot be distributed to each hydraulic actuator according to the control command value. Regarding the manual operation compounded in the MC control, a flow rate corresponding to the operation amount is supplied to the target hydraulic actuator, so that the target hydraulic actuator is driven according to the manual operation of the operator.

[0093] As described above, according to the present embodiment, even when a hydraulic actuator not subject to MC control is manually operated during MC control, it is possible to suppress a decrease in MC control accuracy while ensuring good responsiveness to manual operation as intended by the operator.

[0094] (Second embodiment)

[0095] Figure 7 is a schematic diagram showing the logic of MC control performed by a controller provided in a construction machine according to a second embodiment of the present invention. Figure 8 Yes means Figure 7 Functional block diagram of the detailed processing of target speed calculation. Figure 7 as well as Figure 8 In the drawings, elements that are the same as or correspond to those in the first embodiment are denoted by the same reference numerals as those in the existing drawings, and description thereof is omitted.

[0096] The present embodiment is different from the first embodiment in that the following function is added to the controller 50: based on the output of a detector (e.g., an angle detector D2) that detects the movement of a driven component (e.g., an arm 22) driven by a second hydraulic actuator (e.g., an arm hydraulic cylinder 32), the actual speed of the second hydraulic actuator is estimated and calculated, and the target flow rate Q2 of the second hydraulic actuator is corrected in such a way that the calculated actual speed is consistent with the target speed of the second hydraulic actuator.

[0097] In this embodiment, the controller 50 calculates an estimated value of the driving speed (arm estimated actual speed) related to the actual extension or contraction of the arm hydraulic cylinder 32 based on the change per unit time of the detection signal (arm angle) input from the angle detector D2 (processing 63f). Figure 8 As shown, the target speed v2 (arm target speed) of the boom hydraulic cylinder 32 calculated by the processing 63d is corrected by feedback control based on the estimated actual speed of the boom, and the corrected target speed v2' is output (processing 63g). Figure 7 ) is processed based on the corrected target speed v2', and the target flow rate G2 is calculated. The target speed v1 of the boom hydraulic cylinder 31 is Figure 8 2 shows an example in which the calculation is performed based on the target speed v2 as in the first embodiment, but it is also possible to configure the calculation to be performed based on the corrected target speed v2.

[0098] Regarding other points, this embodiment is the same as the first embodiment.

[0099] According to the above configuration, in addition to the same effects as those of the first embodiment, the difference between the target speed v2 and the actual speed of the second hydraulic actuator (the arm cylinder 32 in this example) can be reduced by feedback control, thereby further improving the MC control accuracy.

[0100] (Third embodiment)

[0101] Fig. 9 is a functional block diagram showing the detailed processing of target speed calculation by the controller of the construction machine according to the third embodiment of the present invention, and is related to Figure 4 and Figure 8 The corresponding figure. Fig. 9 In the drawings, the same or corresponding elements as those in the first embodiment or the second embodiment are denoted by the same reference numerals as those in the existing drawings and description thereof is omitted.

[0102] The present embodiment is different from the first and second embodiments in that the following function is added to the controller 50: limiting the increase in the target speed v2 of the second hydraulic actuator (e.g., the boom cylinder 32) caused by a decrease in the supply flow Q3 of the hydraulic oil from the second hydraulic pump (e.g., the hydraulic pump P2) to the third hydraulic actuator (e.g., the rotary motor 34).

[0103] In this embodiment, the corrected target speed v2' calculated by the process 63g is output via a low-pass filter (process 63h), and is input to the target flow rate calculation 64 ( Figure 7 ) is processed and sent. Fig. 9 6 shows an example of using a low-pass filter in processing 63h, but a rate limiter that limits the rate of increase can also be used. Fig. 9 The example of the second embodiment uses the process 63h, but the first embodiment can also use the process 63h (that is, the process 63f and 63g are omitted). The target speed v1 of the boom cylinder 31 is Fig. 9 2 shows an example in which the calculation is performed based on the target speed v2 as in the first and second embodiments, but the calculation may be performed based on the corrected target speed v2′ or v2″.

[0104] Regarding other points, this embodiment is the same as the first embodiment.

[0105] According to the above-mentioned configuration, on the basis of the same effect as that of the first embodiment or the second embodiment, when the manual operation is released or the operation amount is reduced from a state in which manual operation is combined in the MC control, it is possible to suppress a sudden change in the target speed v2 of the hydraulic actuator related to the MS control and then the actual speed thereof, which is caused by a sudden increase in the flow rate that can be supplied to the hydraulic actuator (for example, the boom hydraulic cylinder 32) related to the MC control due to a reduction in the supply flow rate Q3 to the hydraulic actuator (the third hydraulic actuator) related to the manual operation.

[0106] Thus, according to the present embodiment, even when the difference between the target speed v2' of the boom hydraulic cylinder 32 calculated by the processing 63g and the estimated actual speed of the boom hydraulic cylinder 32 increases rapidly in a short period of time, for example, the drastic speed change of the boom 22 can be prevented, and the discomfort of the operator caused by the shaking of the machine body due to the drastic speed change can be suppressed. In addition, the following effect can be obtained: the reduction in MC control accuracy caused by the speed change of the boom 21, which is heavier than the boom 22 and has a strong inertia effect, not following the drastic speed change of the boom 22 can be suppressed.

[0107] As a specific situation where the difference between the target speed v2' and the estimated actual speed of the boom hydraulic cylinder 32 increases rapidly in a short period of time, the case where the rotation operation that intervenes in the MC control is released is cited. If the operator stops the rotation operation, the upper limit speed v2u is restored to the value allowed by the maximum discharge flow Qmax of the hydraulic pump P2, thereby increasing the target speed v2 of the boom hydraulic cylinder 32. On the other hand, at the moment after the upper limit speed v2u is restored, the estimated actual speed of the boom hydraulic cylinder 32 remains at the speed when the rotation action is compounded due to the response delay. Therefore, the difference between the target speed v2' and the estimated actual speed of the boom hydraulic cylinder 32 increases rapidly in an instant. Fig.10As shown, possible situations in which this situation may occur include, for example, the following: the rotation operation becomes a non-operation (0) from the maximum operation amount, the rotation operation becomes a micro-operation (the operation amount decreases) from the maximum operation amount, and the rotation operation becomes a non-operation (0) from an intermediate operation amount smaller than the maximum operation amount.

[0108] (Variation Example)

[0109] In each of the above embodiments, according to the relationship described in the technical solution, the hydraulic pump P1 is equivalent to the first hydraulic pump, the hydraulic pump P2 is equivalent to the second hydraulic pump, the boom hydraulic cylinder 31 is equivalent to the first hydraulic actuator, the arm hydraulic cylinder 32 is equivalent to the second hydraulic actuator, and the rotary motor 34 is equivalent to the third hydraulic actuator. However, this is not limited to this example. For example, as an example of a hydraulic actuator equivalent to the third actuator, in addition to the rotary motor 34, a bucket hydraulic cylinder 33, or a hydraulic actuator mounted on an attachment such as a positioning hydraulic cylinder and a tilt rotator can also be cited.

[0110] For example, in the MC control for controlling the movement of the arm 22 and the boom 21 by the arm operation, it is not limited to the rotation operation, and there is also a case of a compound bucket operation. In this case, the hydraulic actuator that shares the hydraulic source with the bucket hydraulic cylinder 33 is the boom hydraulic cylinder 31. In the relationship described in the technical proposal, the hydraulic pump P2 is equivalent to the first hydraulic pump, the hydraulic pump P1 is equivalent to the second hydraulic pump, the arm hydraulic cylinder 32 is equivalent to the first hydraulic actuator, the boom hydraulic cylinder 31 is equivalent to the second hydraulic actuator, and the bucket hydraulic cylinder 33 is equivalent to the third hydraulic actuator. In this case, based on the output of the angle detector D3 (sensor), the supply flow rate Q3 of the hydraulic oil from the hydraulic pump P1 (second hydraulic pump) to the bucket hydraulic cylinder 33 (third hydraulic actuator) is calculated, and based on the flow rate difference Qd between the maximum discharge flow rate of the hydraulic pump P1 (second hydraulic pump) and the supply flow rate Q3 to the bucket hydraulic cylinder 33 (third hydraulic actuator), the upper limit speed v1u of the boom hydraulic cylinder 31 (second hydraulic actuator) that can be output at the flow rate difference Qd is calculated. The upper limit speed v1u is compared to the required speed of the boom hydraulic cylinder 31 (second hydraulic actuator) corresponding to the operation signal of the operating device L2 in the operation (arm operation) of the front working machine 20. When the required speed is less than the upper limit speed v1u, the required speed is calculated and used as the target speed v1 of the boom hydraulic cylinder 31 (second hydraulic actuator). When the required speed exceeds the upper limit speed v1u, the upper limit speed v1u is calculated and used as the target speed v1. When the target speed v1 of the boom hydraulic cylinder 31 is limited in this way, the target speed v2 of the boom hydraulic cylinder 32 can also be calculated backwards from the target speed v1 of the boom hydraulic cylinder 31.

[0111] In addition, an example is given of calculating the supply flow Q3 to the third hydraulic actuator (e.g., the rotary motor 34) based on the output of an angle detector (e.g., the angle detector D4), but it is also possible to calculate the supply flow Q3 based on the operation amount of the corresponding operating device (e.g., the operating device L4), for example.

[0112] In the above-mentioned embodiments, an example of using an electric rod device for the operating device L1-L4 is described, but it is also possible to use a pilot operation type in which the operating device L1-L4 is mechanically operated by the operating rod to operate the pilot valve. When the operating device L1-L4 is set to a pilot operation type, the pilot pressure is generated by the pilot valve (pressure reducing valve) mechanically linked to the operating rod, and the pilot pressure is used as the initial pressure to generate the pilot pressure, and the direction switching valve V1-V4 is driven by the pilot pressure. At this time, for example, between the direction switching valves corresponding to the pilot valve, or between the pilot pump P3 and the direction switching valve bypassed from the pilot valve, there are electromagnetic valves Sn1 and Sn2 for MC control. As the rod operation amount, it can be configured so that the pilot pressure output by the pilot valve is detected by a pressure sensor, and it can also be configured so that the rod operation amount itself is detected by a potentiometer or the like.

[0113] In the second embodiment or the third embodiment, an example of estimating the actual value of the rotation speed based on the output of the angle detector D4 is described, but an angular velocity meter that directly detects the angular velocity of the rotation can also be used. In addition, it is also considered to estimate the rotation speed from the rotation operation amount. Moreover, in the event of a sensor failure, a plurality of these methods can be combined to form a structure.

[0114] In addition, an example of calculating the posture of the front working machine 20 based on the output of the angle detectors D1-D3 is described, but for example, a stroke sensor (regardless of the linear type, wheel type, etc.) that detects the stroke of the hydraulic cylinder can also be used. It is also possible to calculate the posture of the front working machine 20 based on the output of an acceleration sensor such as an IMU that detects the angle of a driven component such as the boom 21 based on the direction of gravity. Moreover, in the event of a sensor failure, a plurality of these methods can be combined to form a configuration.

[0115] Description of Reference Numerals

[0116] 10…vehicle body, 12…rotating body (driven component), 20…front working machine, 31…boom hydraulic cylinder (first hydraulic actuator), 32…arm hydraulic cylinder (second hydraulic actuator), 34…rotating motor (third hydraulic actuator), 50…controller, Dn…angle detector (sensor, detector), Ln…operating device, P1…hydraulic pump (first hydraulic pump), P2…hydraulic pump (second hydraulic pump), Vn…direction switching valve, Sn1, Sn2…solenoid valves.

Claims

1. An engineering machine having: Car body; A front working machine mounted on the vehicle body; a first hydraulic pump and a second hydraulic pump mounted on the vehicle body; a first hydraulic actuator that is driven by the discharge oil of the first hydraulic pump and drives the front working machine; a second hydraulic actuator that is driven by the discharge oil of the second hydraulic pump and drives the front working machine; a third hydraulic actuator driven by the discharge oil of the second hydraulic pump; a direction switching valve for controlling the flow of hydraulic oil from the second hydraulic pump to the second hydraulic actuator; a solenoid valve for generating a pilot pressure for driving the directional switching valve; An operating device for operating the front working machine; a sensor for detecting a state quantity corresponding to the action of the third hydraulic actuator; and a controller for controlling the solenoid valve and the first and second hydraulic pumps based on a target surface distance, i.e., a distance between a specific point of the front working machine and a preset target construction surface, and an operation signal corresponding to an operation of the operation device; The engineering machine is characterized in that: The controller is configured as follows: calculating a supply flow rate of the hydraulic oil from the second hydraulic pump to the third hydraulic actuator based on the output of the sensor, The upper limit speed of the second hydraulic actuator is calculated based on the flow rate difference between the maximum flow rate that the second hydraulic pump can discharge and the supply flow rate to the third hydraulic actuator. comparing the required speed of the second hydraulic actuator corresponding to the operation signal with the upper speed limit, When the requested speed is less than the upper limit speed, the requested speed is calculated as a target speed of the second hydraulic actuator, and when the requested speed exceeds the upper limit speed, the upper limit speed is calculated as the target speed. a target flow rate of the second hydraulic pump is calculated by adding the supply flow rate to the third hydraulic actuator to a flow rate corresponding to the target speed of the second hydraulic actuator, The solenoid valve is controlled based on the target speed, and the second hydraulic pump is controlled based on the target flow rate.

2. The construction machine according to claim 1, characterized in that: The state quantity corresponding to the operation of the third hydraulic actuator is an angle change amount of a driven member driven by the third hydraulic actuator or an operation amount of the third hydraulic actuator.

3. The construction machine according to claim 1, characterized in that: A detector for detecting the movement of a driven component driven by the second hydraulic actuator, The controller is configured as follows: calculating the actual speed of the second hydraulic actuator based on the output of the detector, The target flow rate is corrected so that the actual speed coincides with the target speed.

4. The engineering machine according to claim 1, characterized in that: The controller limits an increase in the target speed accompanying a decrease in a supply flow rate of the hydraulic oil from the second hydraulic pump to the third hydraulic actuator to a predetermined value.

Images