Construction machinery

Abstract

A construction machine comprising: first and second hydraulic actuators driven by first and second hydraulic pumps, respectively, to drive a front workpiece; a third hydraulic actuator driven by the second hydraulic pump; an electronic valve to control hydraulic fluid to the second hydraulic actuator; an operating device to operate the front workpiece; and a controller to control the electronic valve and the first and second hydraulic pumps based on the distance between the front workpiece and a target construction surface and an operating signal, wherein the controller calculates an upper limit speed of the second hydraulic actuator based on the difference in flow rate between the maximum reading flow rate of the second hydraulic pump and the supply flow rate to the third hydraulic actuator, calculates a target speed of the second hydraulic actuator by limiting the required speed of the second hydraulic actuator according to the operating signal to the upper limit speed, and controls the electronic valve and the second hydraulic pump according to the target speed.

Description

Technology Field

[0001] The present invention relates to construction machinery such as hydraulic shovels. Background Technology

[0002] In recent years, due to the utilization of ICT, information-based construction has been introduced at construction sites, and construction machinery equipped with machine control (hereinafter abbreviated as MC) functions that automatically or semi-automatically control front implements according to the design terrain (target construction surface) of the construction site is becoming widespread. In this specification, "automatic control" refers to control in which a controller drives a hydraulic actuator that is not being operated by an operator, and "semi-automatic control" refers to control in which a controller corrects the operation of a hydraulic actuator that is being operated by an operator by intervening in the operator's operation.

[0003] However, at construction sites, even while working with the MC function, there are cases where the operator operates hydraulic actuators other than the hydraulic actuators that are the target of the MC. For example, while driving a front work machine using the MC function, if the machine cannot be positioned facing the construction surface directly due to the working environment, or if the number of movements of the machine is limited by expanding the working range, the operator may operate attachments such as a positioning cylinder or a tilt rotator, or operate the slewing body.

[0004] In MC control, a target flow rate is calculated to drive the hydraulic actuator at a target speed based on the operator's operation, and the discharge flow rate of the hydraulic pump and the pilot pressure of the control valve are controlled. When multiple hydraulic actuators operate in combination, the discharge flow rate of the hydraulic pump is determined according to the target speed and target flow rate of each hydraulic actuator; however, the maximum flow rate that the hydraulic pump can discharge is determined by the hydraulic pump's specifications. Therefore, if the total target flow rate of the multiple hydraulic actuators being driven exceeds the hydraulic pump's maximum discharge flow rate, the individual hydraulic actuators may not be driven at their target speeds. In this case, the precision of the MC control is reduced, which may result in the construction site being formed according to the design or the machine being 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 supplements the shortfall by combining the discharge fluid of another hydraulic pump when the maximum discharge flow rate of a hydraulic pump is insufficient compared to the total target flow rate of a plurality of hydraulic actuators. Prior art literature

[0006] Japanese Patent Publication No. 2007-100779 The problem to be solved

[0007] Generally, when multiple hydraulic actuators connected to the same hydraulic pump operate simultaneously, the discharge fluid from the hydraulic pump tends to flow into the hydraulic actuator with the lower load pressure. On the other hand, the fewer the branching or merging of the fluid paths connecting the hydraulic actuator and the hydraulic pump, the more the influence of the load pressure on the control of the supply flow rate to each hydraulic actuator can be suppressed. Therefore, in MC control, it is desirable to minimize the number of hydraulic pumps and hydraulic actuators connected to the same fluid path to suppress the branching or merging of the discharge fluid from the hydraulic pump.

[0008] In contrast, the hydraulic control device described in Patent Document 1 secures the target flow rate of the hydraulic actuator by combining the discharge fluid from another hydraulic pump when the maximum discharge flow rate of the hydraulic pump is insufficient for the target flow rate of the hydraulic actuator. However, in such a configuration, the number of parts for classifying and combining the discharge fluid of the hydraulic pump increases, making it susceptible to the influence of the load pressure of each hydraulic actuator, and there is a risk that the precision of MC control will decrease as the classification becomes complex during combined operation.

[0009] An example of a task using MC control is called excavation. Excavation is a leveling operation in which the boom and arm are linked to excavate the ground in front of the machine to ensure the height of the excavation surface is uniform. In this case, for instance, when the boom cylinder is driven by the first hydraulic pump and the arm cylinder is driven by the second hydraulic pump, the hydraulic actuator and the hydraulic pump have a one-to-one relationship, so there is no separation or merging, and the precision of the MC control is maintained at a high level. In this excavation operation, there are cases where a slewing motion is operated while the boom and arm are driven under MC control, with the intention of expanding the leveling range without moving the vehicle body. In this case, if the circuit configuration is such that the slewing motor is driven by the second hydraulic pump, unlike when the excavation operation is performed solely by the movement of the boom and arm, the discharge fluid from the second hydraulic pump is separated into the arm cylinder and the slewing motor. In this situation, if the total target flow rate of the arm cylinder and the swing motor exceeds the maximum discharge flow rate of the second hydraulic pump due to the operator's operation, the maximum discharge flow rate of the second hydraulic pump is insufficient for the target flow rate. In this example, in the technology described in Patent Document 1, the target flow rates of the arm cylinder and the swing motor can be secured by joining the discharge fluid of the first hydraulic pump to the flow path of the second hydraulic pump. However, by joining the discharge fluids of the first hydraulic pump and the second hydraulic pump in this way, the discharge fluid of the first hydraulic pump, as well as the discharge fluid of the second hydraulic pump, is diverted to the boom cylinder, arm cylinder, and swing motor. As a result, the load pressure of the first hydraulic pump and the boom cylinder affects the MC control regarding the excavation work, and there is a risk that the precision of the MC control will decrease.

[0010] The objective of the present invention is to provide a construction machine capable of suppressing a decrease in the precision of MC control while ensuring good responsiveness to the operation intended by the operator, even when a hydraulic actuator that is not the subject of MC control is operated during MC control. means of solving the problem

[0011] To achieve the above objective, the present invention comprises a vehicle body, a front work device installed on the vehicle body, a first hydraulic pump and a second hydraulic pump mounted on the vehicle body, a first hydraulic actuator driven by the discharge path of the first hydraulic pump to drive the front work device, a second hydraulic actuator driven by the discharge path of the second hydraulic pump to drive the front work device, a third hydraulic actuator driven by the discharge path of the second hydraulic pump, a directional control valve that controls the flow of hydraulic fluid from the second hydraulic pump to the second hydraulic actuator, an electronic valve that generates a pilot pressure to drive the directional control valve, an operating device for operating the front work device, a sensor that detects a state quantity corresponding to the operation of the third hydraulic actuator, a target surface distance which is the distance between a specific point of the front work device and a preset target construction surface, and a controller that controls the electronic valve, the first hydraulic pump, and the second hydraulic pump based on an operating signal according to the operation of the operating device. In the machine, the controller calculates the supply flow rate of hydraulic fluid from the second hydraulic pump to the third hydraulic actuator based on the output of the sensor, calculates the upper limit speed of the second hydraulic actuator based on the difference between the maximum flow rate that the second hydraulic pump can discharge and the supply flow rate to the third hydraulic actuator, compares the required speed of the second hydraulic actuator according to the operation signal with the upper limit speed, calculates the required speed as the target speed of the second hydraulic actuator if the required speed is less than or equal to the upper limit speed, calculates the upper speed as the target speed if the required speed exceeds the upper limit speed, calculates the upper speed as the target speed, and calculates the target flow rate of the second hydraulic pump by adding the supply flow rate to the third hydraulic actuator to the flow rate according to the target speed of the second hydraulic actuator.A construction machine is provided that controls the electronic valve based on the above target speed and controls the second hydraulic pump based on the above target flow rate. Effects of the invention

[0012] According to the present invention, a construction machine can be provided that can suppress a decrease in the precision of MC control while ensuring good responsiveness to manual operation intended by the operator, even when a hydraulic actuator that is not the target of MC control is manually operated during MC control. Brief explanation of the drawing

[0013] FIG. 1 is a side view of a hydraulic shovel, which is an example of a construction machine according to a first embodiment of the present invention. FIG. 2 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. FIG. 3 is a schematic diagram illustrating the logic of MC control by a controller equipped in a construction machine according to a first embodiment of the present invention. FIG. 4 is a functional block diagram illustrating the details of the processing of target speed calculation (Fig. 3) by a controller equipped in a construction machine according to a first embodiment of the present invention. FIG. 5 is a functional block diagram illustrating the details of the processing of pump flow rate calculation (Fig. 3) by a controller equipped in a construction machine according to a first embodiment of the present invention. FIG. 6 is a drawing illustrating an example of the trend of the target flow rate of the second hydraulic pump and the target flow rate of the arm cylinder occupied therein when a slewing operation is intervened during MC control in the first embodiment of the present invention. FIG. 7 is a schematic diagram illustrating the logic of MC control by a controller equipped in a construction machine according to a second embodiment of the present invention. FIG. 8 is a functional block diagram illustrating the details of the processing of target speed calculation (Fig. 7) by a controller equipped in a construction machine according to a second embodiment of the present invention. FIG. 9 is a functional block diagram illustrating the details of the processing of target speed calculation by a controller equipped in a construction machine according to a third embodiment of the present invention. FIG. 10 is a drawing illustrating an example where the difference between the target speed and the estimated actual speed of the second hydraulic actuator increases rapidly in a short period of time. Specific details for implementing the invention

[0014] Embodiments of the present invention will be described below using the drawings.

[0015] (First embodiment)

[0016] 1. Construction machinery

[0017] FIG. 1 is a side view of a hydraulic shovel, which is an example of a construction machine according to a first embodiment of the present invention. In this embodiment, a hydraulic shovel equipped with a bucket (23) as an attachment to the tip of a front working device (20) (working device) is described as an example of a construction machine. However, the present invention may also be applied to a hydraulic shovel equipped with an attachment other than a bucket, or to other types of construction machines such as a wheel loader or a bulldozer. In this specification, the front of the cab (16) (right side in FIG. 1) is defined as the front of the hydraulic shovel (strictly speaking, the slewing body (12)).

[0018] The hydraulic shovel illustrated in the drawing comprises a vehicle body (10) and a front work device (20) installed on the vehicle body (10). The vehicle body (10) comprises a driving body (11) and a turning body (12).

[0019] In this embodiment, the driving body (11) is equipped with a crawler-type left and right driving device (13) having an endless crawler belt, and drives by driving the left and right driving devices (13) respectively by the left and right driving motors (14). A hydraulic motor is used for the driving motor (14).

[0020] The swivel body (12) is provided to be swivelable via a swivel device (15) on the upper part of the driving body (11). The swivel device (15) connecting the driving body (11) and the swivel body (12) includes a swivel motor (34), and when the swivel motor (34) is driven, the swivel body (12) swivels around a vertical central axis relative to the driving body (11). The swivel motor (34) is a hydraulic actuator (hydraulic motor). A driver's cabin (16) for an operator to ride in is provided in the front part of the swivel body (12) (in this embodiment, the left side of the front part). A machine room (17) for housing hydraulic pumps P1, P2 (Fig. 2), etc. is located on the rear side of the driver's cabin (16) in the swivel body (12), and a counterweight (18) for balancing the weight with the front work machine (20) is mounted at the rear end.

[0021] The front work unit (20) is a multi-jointed work arm for performing tasks such as excavating soil, and is connected to the front part of the slewing body (12) (in this embodiment, the right side of the driver's cabin (16)). This front work unit (20) is composed of a boom (21), an arm (22), and a bucket (23). The boom (21) is connected by a pin to the slewing frame (19), which is the base frame of the slewing body (12), and rotates up and down relative to the slewing body (12) in conjunction with the extension and retraction of the boom cylinder (31). Both ends of the boom cylinder (31) are rotatably connected to the boom (21) and the slewing body (12). The arm (22) is connected by a pin to the tip of the boom (21) and rotates back and forth relative to the boom (21) in conjunction with the extension and retraction of the arm cylinder (32). Both ends of the arm 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) in conjunction with the extension and retraction of the bucket cylinder (33). 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), arm cylinder (32), and bucket cylinder (33) that drive the front work machine (20) are hydraulic actuators.

[0022] Additionally, angle detectors D1-D3 are provided at each rotational support point of the boom (21), arm (22), and bucket (23), and angle detector D4 is provided at the rotation device (15) of the rotation body (12). Angle detector D1 is a detector that detects a state quantity corresponding to the operation of the boom (21), which is a driven member driven by the boom cylinder (31), and in this embodiment, detects the rotation angle of the boom (21) relative to the rotation frame (19) and outputs it to the controller (50). Angle detector D2 is a detector that detects a state quantity corresponding to the operation of the arm (22), which is a driven member driven by the arm cylinder (32), and in this embodiment, detects the rotation angle of the arm (22) relative to the boom (21) and outputs it to the controller (50). Angle detector D3 is a detector that detects a state quantity corresponding to the operation of a bucket (23), which is a driven member driven by a bucket cylinder (33), and in this embodiment, detects the rotation angle of the bucket (23) relative to the arm (22) and outputs it to the controller (50). Angle detector D4 is a detector that detects a state quantity corresponding to the operation of a swivel body (12), which is a driven member driven by a swivel motor (34), and in this embodiment, detects the rotation angle of the swivel body (12) relative to the driving body (11) and outputs it to the controller (50). In MC control, the attitude of the front work machine (20) is calculated based on the output (detection signal) of angle detectors D1-S5. In addition, the swivel speed of the swivel body (12) is calculated based on the output (detection signal) of angle detector D4. Angle detectors D1-D4 are examples of detectors that detect the operation of a driven member (boom (21), arm (22), bucket (23), slewing body (12)) driven by a corresponding hydraulic actuator, and the time change amount of each rotation angle detected by angle detectors D1-D4 is an example of a state quantity in which the change amount corresponds to the operation of the corresponding hydraulic actuator.

[0023] 2. Hydraulic System

[0024] FIG. 2 is a hydraulic circuit diagram of the main part of the hydraulic system mounted on the hydraulic shovel of FIG. 1. FIG. 2 shows the circuit driving the boom cylinder (31), arm cylinder (32), bucket cylinder (33), and slewing motor (34).

[0025] The hydraulic system illustrated in FIG. 2 is equipped with a plurality (two in this embodiment) of 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).

[0026] 2-1. Hydraulic Pump

[0027] Hydraulic pumps P1 and P2 are hydraulic sources for each hydraulic actuator mounted on a hydraulic shovel, such as a boom cylinder (31), arm cylinder (32), bucket cylinder (33), and slewing motor (34), and are mounted together with a prime mover (E) in the vehicle body (10) (machine room (17)). Hydraulic pumps P1 and P2 are driven by the prime mover (E), suck in hydraulic fluid from the hydraulic fluid tank (T) to increase the pressure, and discharge hydraulic fluid to drive the corresponding hydraulic actuator. In FIG. 2, an engine (internal combustion engine) is shown as the prime mover (E), but an electric motor may be used as the prime mover (E). Hydraulic pumps P1 and P2 are each variable displacement pumps whose capacity is controlled by pump regulators R1 and R2. FIG. 2 illustrates a hydraulic system equipped with two hydraulic pumps P1 and P2, but there may be cases where three or more hydraulic pumps are equipped in the hydraulic system.

[0028] The hydraulic fluid discharged from hydraulic pump P1 flows through pump line PL1, which is the discharge path of hydraulic pump P1, and passes through directional control valves V1 and V3 to be supplied to boom cylinder (31) and bucket cylinder (33). Accordingly, the return fluid discharged from boom cylinder (31) and bucket cylinder (33) flows into tank line TL through directional control valves V1 and V3 and is returned to the hydraulic fluid tank (T). Although not shown in the illustration, pump line PL1 and tank line TL are connected through a relief valve that regulates the maximum pressure of pump line PL1.

[0029] Likewise, the hydraulic fluid discharged from the hydraulic pump P2 flows through the pump line PL2, which is the discharge path of the hydraulic pump P2, and passes through the directional control valves V2 and V4 to be supplied to the arm cylinder (32) and the slewing motor (34). In conjunction with this, the return fluid discharged from the arm cylinder (32) and the slewing motor (34) flows into the tank line TL through the directional control valves V2 and V4 and is returned to the hydraulic fluid tank (T). Although not shown in the illustration, the pump line PL2 and the tank line TL are connected through a relief valve that regulates the maximum pressure of the pump line PL2.

[0030] In the hydraulic system of the present embodiment, pump lines PL1 and PL2 are independent of each other, and the hydraulic fluid flowing through pump lines PL1 and PL2 is not combined and supplied to a hydraulic actuator. That is, there is no fluid path provided to directly connect pump lines PL1 and PL2 by bypassing the boom cylinder (31), arm cylinder (32), bucket cylinder (33), and slewing motor (34). However, while it is preferable for pump lines PL1 and PL2 to be independent, pump lines PL1 and PL2 may be connected to combine the discharge fluid from hydraulic pumps P1 and P2 and supply it to the same hydraulic actuator.

[0031] 2-2. Pilot Pump

[0032] Pilot pump P3 is a fixed-displacement pump that outputs the primary pressure (original pressure) of the pilot pressure, which drives a hydraulically driven control valve, such as a directional control valve Vn, included in a hydraulic system. This pilot pump P3 is driven by a prime mover (E), just like hydraulic pumps P1 and P2. However, the pilot pump P3 may be configured to be driven by a power source different from the prime mover (E).

[0033] 2-3. Directional Control Valve

[0034] The direction change valve Vn (n=1, 2, 3, 4) controls the flow (direction and flow rate) of hydraulic fluid supplied to the boom cylinder (31), arm cylinder (32), bucket cylinder (33), and slewing motor (34).

[0035] The directional control valve V1 is for boom driving, and the spool is driven by the pilot pressure input to its pilot valve and the restoring force of the spring to control the supply and stop of hydraulic fluid to the boom cylinder (31). In addition to the pump line PL1 and tank line TL of the hydraulic pump P1, the bottom side valve and rod side valve of the boom cylinder (31) are connected to each port of the directional control valve V1. When the pump line PL1 is connected to the bottom side valve by the directional control valve V1, the boom cylinder (31) extends and the boom (21) moves upward. Conversely, when the pump line PL1 is connected to the rod side valve by the directional control valve V1, the boom cylinder (31) retracts and the boom (21) moves downward. When pilot pressure is not applied to the pilot loss, the spool of the directional control valve V1 is in a neutral position due to the restoring force of the spring, and the connection between the boom cylinder (31) and the pump line PL1 and tank line TL is cut off, and the boom cylinder (31) stops.

[0036] Just like the directional control valve V1 for the boom cylinder (31), the directional control valve V2 for the arm cylinder (32), the directional control valve V3 for the bucket cylinder (33), and the directional control valve V4 for the slewing motor (34) are also driven by pilot pressure and the restoring force of a spring.

[0037] Each port of the directional control valve V3 for bucket driving is connected to the pump line PL1 of the hydraulic pump P1, the tank line TL, and the bottom side and load side of the bucket cylinder (33). When the pump line PL1 is connected to the bottom side of the bucket cylinder (33) by the directional control valve V3, the bucket cylinder (33) extends and the bucket (23) moves. Conversely, when the pump line PL1 is connected to the load side of the bucket cylinder (33) by the directional control valve V3, the bucket cylinder (33) retracts and the bucket (23) moves. When the directional control valve V3 returns to the neutral position, the bucket cylinder (33) stops.

[0038] Each port of the directional control valve V2 for driving the arm is connected to the pump line PL2 of the hydraulic pump P2, the tank line TL, and the bottom side and rod side of the arm cylinder (32). When the pump line PL2 is connected to the bottom side of the arm cylinder (32) by the directional control valve V2, the arm cylinder (32) extends and the arm (22) moves. Conversely, when the pump line PL2 is connected to the rod side of the arm cylinder (32) by the directional control valve V2, the arm cylinder (32) retracts and the arm (22) moves. When the directional control valve V2 returns to the neutral position, the arm cylinder (32) stops.

[0039] Each port of the directional control valve V4 for the slewing drive is connected to the pump line PL2 of the hydraulic pump P2, the tank line TL, and one port and the other port of the slewing motor (34). When the pump line PL2 is connected to one port of the slewing motor (34) by the directional control valve V4, the slewing motor (34) rotates forward, causing the slewing body (12) to slewing in one direction. Conversely, when the pump line PL2 is connected to the other port of the slewing motor (34) by the directional control valve V4, the slewing motor (34) rotates backward, causing the slewing body (12) to slewing in the other direction. When the directional control valve V4 returns to the neutral position, the slewing motor (34) stops.

[0040] 2-5. Electronic Valve

[0041] Solenoid valves Sn1 and Sn2 (n=1, 2, 3, 4) are electronically driven proportional pressure reducing valves that generate a pilot pressure to drive the directional control valve Vn (n=1, 2, 3, 4). A pilot primary pressure line PL3, which is the discharge path of the pilot pump P3, is connected to solenoid valves Sn1 and Sn2. Solenoid valves Sn1 and Sn2 are driven by a command signal from the controller (50) and reduce the pressure of the pilot primary pressure line PL3 to generate a pilot pressure (pilot secondary pressure).

[0042] Solenoid valves S11 and S12 generate pilot pressure to drive the directional control valve V1 for boom driving and output it to the pilot chamber of the directional control valve V1. Solenoid valve S11 is for boom raising operation, and when the pilot pressure output by solenoid valve S11 is input to the directional control valve V1, the discharge fluid of hydraulic pump P1 is supplied to the bottom-side chamber of the boom cylinder (31), causing the boom cylinder (31) to extend. Solenoid valve S12 is for boom lowering operation, and when the pilot pressure output by solenoid valve S12 is input to the directional control valve V1, the discharge fluid of hydraulic pump P1 is supplied to the rod-side chamber of the boom cylinder (31), causing the boom cylinder (31) to contract.

[0043] Solenoid valves S21 and S22 generate pilot pressure to drive the direction change valve V2 for arm driving and output it to the pilot chamber of the direction change valve V2. Solenoid valve S21 is for arm crowding operation, and when the pilot pressure output by solenoid valve S21 is input to the direction change valve V2, the discharge fluid of hydraulic pump P2 is supplied to the bottom side chamber of the arm cylinder (32), causing the arm cylinder (32) to extend. Solenoid valve S22 is for arm dump operation, and when the pilot pressure output by solenoid valve S22 is input to the direction change valve V2, the discharge fluid of hydraulic pump P2 is supplied to the rod side chamber of the arm cylinder (32), causing the arm cylinder (32) to contract.

[0044] Solenoid valves S31 and S32 generate pilot pressure to drive the directional control valve V3 for bucket operation and output it to the pilot chamber of the directional control valve V3. Solenoid valve S31 is for bucket crowd operation, and when the pilot pressure output by solenoid valve S31 is input to the directional control valve V3, the discharge fluid of hydraulic pump P1 is supplied to the bottom-side chamber of the bucket cylinder (33), causing the bucket cylinder (33) to extend. Solenoid valve S32 is for bucket dump operation, and when the pilot pressure output by solenoid valve S32 is input to the directional control valve V3, the discharge fluid of hydraulic pump P1 is supplied to the rod-side chamber of the bucket cylinder (33), causing the bucket cylinder (33) to contract.

[0045] Solenoid valves S41 and S42 generate a pilot pressure to drive the directional control valve V4 for pivoting and output it to the pilot valve of the directional control valve V4. Solenoid valve S41 is for left pivoting operation, and when the pilot pressure output by solenoid valve S41 is input to the directional control valve V4, the discharge fluid of hydraulic pump P2 is supplied to one side port of the pivot motor (34), causing the pivot motor (34) to rotate in the forward direction. Solenoid valve S42 is for right pivoting operation, and when the pilot pressure output by solenoid valve S42 is input to the directional control valve V4, the discharge fluid of hydraulic pump P2 is supplied to the other side port of the pivot motor (34), causing the pivot motor (34) to rotate in the reverse direction.

[0046] In addition, the pilot pressure output by the electronic valves Sn1 and Sn2 is detected by the pressure sensor (Ps) and input to the controller (50).

[0047] 2-6. Control Device

[0048] Operating devices L1-L4 are operating lever devices (electric lever devices in this embodiment) that operate the corresponding hydraulic actuators by operating the direction change valves V1-V4, respectively, and are installed inside the driver's cabin (16). Operating device L1 is an operating lever device for boom operation that operates the boom cylinder (31). Operating device L2 is an operating lever device for arm operation that operates the arm cylinder (32). Operating device L3 is an operating lever device for bucket operation that operates the bucket cylinder (33). Operating device L4 is an operating lever device for slewing operation that operates the slewing motor (34).

[0049] The operating devices L1-L4 share two operating levers, for example, operating devices L1 and L3 share one operating lever and are positioned to the right of the driver's seat (not shown). When this operating lever is tilted left or right, the bucket (23) operates, and when it is tilted forward or backward, the boom (21) operates. Additionally, operating devices L2 and L4 share one operating lever and are positioned to the left of the driver's seat (not shown). When this operating lever is tilted left or right, the arm (22) operates, and when it is tilted forward or backward, the slewing body (12) slewing. The corresponding relationship between the operating direction of these operating levers and the hydraulic actuators can be appropriately changed. The operating devices L1-L4 are equipped with sensors, such as potentiometers, that detect the amount of lever operation and output it to the controller (50). The amount of each lever operation of operating devices L1-L4 detected by these sensors is an example of a state quantity in which the change amount corresponds to the operation of the corresponding hydraulic actuator.

[0050] 3. Controller

[0051] The controller (50) is a vehicle-mounted computer mounted on the vehicle body (10) and has the function of controlling a hydraulic actuator that drives the front work machine (20), and in this embodiment, a boom cylinder (31) and an arm cylinder (32). The controller (50) is equipped with a computing device (51), a memory device (52), and signal input / output ports, etc. The computing device (51) performs the execution of each computing process, such as the MC control computing unit (53) and the MC control correction unit (54), and outputs control signals to electronic valves Sn1 and Sn2 or pump regulators R1 and R2. The memory device (52) stores data, for example, of a target construction surface of a work site that is pre-set by an operator. The MC control computing unit (53) and the MC control correction unit (54) are functions executed by the controller (50) (computing device (51)), and may be virtually realized by software or realized by hardware such as electronic circuits. The controller (50) receives the output (detection signal, operation signal) of angle detectors D1-D4, operation devices L1-L4, and each pressure sensor (Ps).

[0052] In this embodiment, the MC control calculation unit (53) controls, for example, electronic valves S11, S12, S21, and S22 according to a target surface distance, which is the distance between a specific point of the front work device (20) (typically the claw end of the bucket (23)) and a preset target construction surface, and an operation signal regarding the operation of the operating device L2, thereby controlling the boom cylinder (31) and arm cylinder (32) in conjunction (MC control). Additionally, although not explicitly described, the hydraulic shovel is equipped with a GNSS mobile station that acquires data on the position or orientation of the vehicle body (10) and an attitude sensor that detects the attitude (angle of inclination in the front, back, left, and right directions) of the vehicle body (10), and the MC control calculation unit (53) generally calculates the target surface distance based on data such as the position, orientation, and attitude of the vehicle body (10) relative to the target construction surface.

[0053] In addition, in this embodiment, hydraulic pump P1 is the first hydraulic pump, hydraulic pump P2 is the second hydraulic pump, boom cylinder (31) is the first hydraulic actuator subject to MC control, and arm cylinder (32) is the second hydraulic actuator subject to MC control. The slewing motor (34) is the third hydraulic actuator not subject to MC control. For example, when the MC control function is enabled and the target surface distance is less than or equal to a set value, if an arm claw operation is performed, the controller (50) controls pump regulators R1 and R2 or electronic valves S11, S12, and S21 so that the claw end of the bucket (23) moves along the target construction surface to cut the ground surface, thereby linking the boom (21) to the operation of the arm (22). However, even while this MC control is functioning, manual interlocking operations of the bucket cylinder (33) or the slewing motor (34) are possible.

[0054] The MC control correction unit (54) corrects the target speed of the hydraulic actuators for MC control when, while MC control is in operation, an asymmetric hydraulic actuator of MC control is operated (i.e., manual operation is combined with MC control) and the number of hydraulic actuators supplied with hydraulic fluid from the same hydraulic pump increases. As a specific example, when a slewing operation is interrupted during MC control regarding the linkage of the boom (21) and the arm (22), the supply flow rate of hydraulic fluid to the slewing motor (34) is calculated based on the output of the angle detector D4, and when it is determined that an effect occurs on MC control (the required flow rate of the arm cylinder (32) cannot be supplied from the hydraulic pump P2), the target speed of the arm cylinder (32) that shares a hydraulic source with the slewing motor (34) is corrected. The correction mentioned here refers to correcting the target speed of the arm cylinder (32) in a decreasing direction from the value resulting from arm operation 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 slewing motor (34) from the maximum dischargeable flow rate of the hydraulic pump P2.

[0055] Next, a specific example of control logic by the MC control operation unit (53) and MC control correction unit (54) of the controller (50) will be described.

[0056] 3-1. MC Control

[0057] FIG. 3 is a schematic diagram illustrating the logic of MC control by the controller (50) in the first embodiment. FIG. 3 illustrates an algorithm of MC control in which, when the arm (22) is operated by the operating device L2, the boom (21) also operates in conjunction with the arm (22) and moves the tip of the bucket (23) along the target construction surface.

[0058] In the example of FIG. 3, the controller (50) repeatedly performs a series of processes, such as a spin speed calculation (61), a spin flow rate calculation (62), a target speed calculation (63), a target flow rate calculation (64), and a pump flow rate calculation (65), in short cycles (e.g., 0.1s) while the MC control function is enabled.

[0059] 3-2. MC Control Operation Unit (Basic Processing)

[0060] The controller (50), as a basic processing for MC control (corresponding to the processing content of the MC control calculation unit (53)), first calculates the target speed v2 of the arm cylinder (32) (second hydraulic actuator) based on the operation signal (arm operation amount) of the operating device L2, and at the same time calculates the target speed v1 of the boom cylinder (31) (first hydraulic actuator) based on the target speed v2 of the arm cylinder (32), the position or orientation, attitude, and target plane distance of the vehicle body (10) (target speed calculation (63)). Then, the controller (50) calculates the respective opening degree command values ​​of the direction change valves V1 and V2 according to the target speeds v1 and v2 using, for example, a conversion table, and outputs the command signal according to each opening degree command value to the corresponding electronic valve to control the direction change valves V1 and V2.

[0061] At the same time, the controller (50) calculates the target flow rate Q1 of the hydraulic fluid supplied to the boom cylinder (31) (first hydraulic actuator) based on the target speed v1, and calculates the target flow rate Q2 of the hydraulic fluid supplied to the arm cylinder (32) (second hydraulic actuator) based on the target speed v2 (target flow rate calculation (64)). Then, the controller (50) calculates the total flow rate of the target flow rate Q1 for boom driving and the target flow rate for bucket driving as the target flow rate Qp1 of the hydraulic pump P1, and controls the hydraulic pump P1 (first hydraulic pump) by outputting a pump control command according to the target flow rate Qp1 (pump flow rate calculation (65)). In the case of no interference with bucket operation, the target flow rate Qp1 corresponds to the target flow rate Q1 for boom driving. Additionally, the controller (50) calculates the sum of the target flow rate Q2 for arm drive and the target flow rate for slewing drive as the target flow rate Qp2, and outputs a pump control command according to the target flow rate Qp2 to control the hydraulic pump P2 (second hydraulic pump) (pump flow rate calculation (65)). In the case where there is no interruption of the slewing operation, the target flow rate Qp2 corresponds to the target flow rate Q2 for arm drive.

[0062] As a result of the processing of the MC control operation unit (53) as described above, the boom cylinder (31) (first hydraulic actuator) and the arm cylinder (32) (second hydraulic actuator) are controlled in conjunction.

[0063] 3-3. MC Control Correction Unit (Correction Processing)

[0064] In addition, in the processing of the above MC control calculation unit (53), correction processing of target speeds v1 and v2 (processing of MC control correction unit (54)) is built in, and slewing operations or bucket operations combined with MC control are added to the target speeds v1 and v2. Specifically, when the maximum discharge flow rate Qmax of each hydraulic pump P1 and P2 is insufficient for the total required flow rate of the assigned hydraulic actuator, the target speeds v1 and v2 of the hydraulic actuator regarding MC control are limited. Below, regarding the processing of the MC control correction unit (54), an example is given in which a slewing operation is inserted during MC control regarding the interlocking control of the boom (21) and arm (22) according to the target construction surface.

[0065] In the correction processing regarding the MC control correction unit (54), the controller (50) first calculates the turning speed v3 of the turning body (12) based on the output of the angle detector D4 (sensor) (turning speed calculation (61)), and calculates the supply flow rate Q3 of hydraulic fluid from the hydraulic pump P2 (second hydraulic pump) to the turning motor (34) (third hydraulic actuator) based on the turning speed v3 (turning flow rate calculation (62)). For example, if turning operation is performed by the operating device L4 and the turning body (12) is turning according to the turning operation signal, a turning speed v3 and a supply flow rate Q3 with an absolute value greater than 0 are calculated. If the operating device L4 is not operated and the turning body (12) is stopped, the calculation result of the turning speed v3 and supply flow rate Q3 becomes 0.

[0066] The supply flow rate Q3 to the slewing motor (34) (third hydraulic actuator) calculated in the processing of the slewing flow rate calculation (62) is reflected in the calculation of target speeds v1 and v2 in the target speed calculation (63) and in the control of 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 arm cylinder (32) and is also reflected in the target speed v1 of the boom cylinder (31) according to the target speed v2. As a result, when a slewing operation by an operator is combined during MC control, the control command value to the electronic valve or hydraulic pump changes.

[0067] FIG. 4 is a functional block diagram illustrating the details of the processing of the target speed calculation (63) of FIG. 3.

[0068] In processing the target speed calculation (63), the controller (50) first calculates the flow rate difference Qd by subtracting the supply flow rate Q3 (swivel flow rate) to the swivel motor (34) from the maximum flow rate Qmax that the hydraulic pump P2 (second hydraulic pump) can discharge (process 63a). The flow rate difference Qd corresponds to the maximum flow rate that can be supplied to the arm cylinder (32) by only the hydraulic pump P2 without combining the discharge fluid of the hydraulic pump P1 with the discharge fluid of the hydraulic pump P2. Next, the controller (50) calculates the upper limit speed v2u of the arm cylinder (32) (second hydraulic actuator) that can be produced at the flow rate difference Qd, based on the flow rate difference Qd (process 63b). At the same time as the calculation of the upper speed v2u, the controller (50) calculates the required speed v2r (arm required speed) of the arm cylinder (32) (second hydraulic actuator) according to the operation signal (arm operation amount) of the operation device L2 regarding arm operation (processing 63c).

[0069] Then, the controller (50) compares the required speed v2r and the upper limit speed v2u of the arm cylinder (32) and calculates the target speed v2 (arm target speed) of the arm cylinder (32) (second hydraulic actuator) by selecting the minimum value (process 63d). The target speed v2 is not necessarily limited to a value (arm required speed) based on the arm operation amount, but can be corrected based on the pivoting motion (operation of the third hydraulic actuator). Specifically, if the required speed v2r is less than or equal to the upper limit speed v2u, the required speed v2r is calculated as the target speed v2, and if the required speed v2r exceeds the upper limit speed v2u, the upper limit speed v2u is calculated as the target speed v2. That is, the target speed v2 of the arm cylinder (32) is limited to the upper limit speed v2u. In other words, the target speed v2 of the arm cylinder (32) is limited to the flow rate that can be supplied from the hydraulic pump P2 to the arm cylinder (32) after securing the supply flow rate Q3 to the pivot motor (34) according to the pivot operation.

[0070] When the target speed v2 is calculated in this way, the controller (50) calculates the target speed v1 of the boom cylinder (31) (hereinafter, target speed v1) based on the target speed v2 of the arm cylinder (32) and, for example, the vehicle body attitude or target surface distance (process 63e).

[0071] As described in FIG. 3, the target speeds v1 and v2 are used to calculate the command values ​​of the electronic valve or the target flow rates Q1 and Q2 of the boom cylinder (31) and arm cylinder (32).

[0072] FIG. 5 is a functional block diagram illustrating the details of the processing of the pump flow rate calculation (65) of FIG. 3.

[0073] In the process of pump flow rate calculation (65), the controller (50) first calculates the target flow rate Qp2 of hydraulic pump P2 (second hydraulic pump) by adding the supply flow rate Q3 (swivel flow rate) to the swivel motor (34) (third hydraulic actuator) to the target flow rate Q2 (arm crow target flow rate or arm dump target flow rate) according to the target speed v2 of the arm cylinder (32) (second hydraulic actuator) (process 65a). When the target flow rate Qp2 is calculated, the controller (50) converts the target flow rate Qp2 into a control command value, for example, in a conversion table, outputs a control command value (second hydraulic pump control command) based on the target flow rate Qp2, and controls hydraulic pump P2 (second hydraulic pump) (process 65c). Also, although not shown in FIG. 5, hydraulic pump P1 (first hydraulic pump) is also controlled according to the target flow rate Qp1 in the same manner. In parallel with this, the controller (50) converts target speeds v1 and v2 into control command values, for example, in a conversion table, outputs control command values ​​based on target speeds v1 and v2, and controls the electronic valve (S11 or S12) and the electronic valve (S21 or S22) (Fig. 3).

[0074] In addition, since the maximum and minimum values ​​of the flow rate that can be discharged by hydraulic pump P2 are predetermined by the specifications of hydraulic pump P2, the maximum value of the target flow rate Qp2 input to process 65c is limited to the maximum discharge flow rate Qmax (maximum flow rate of the second hydraulic pump) of hydraulic pump P2, and the minimum value of the target flow rate Qp2 is limited to the minimum flow rate Qmin (minimum flow rate of the second hydraulic pump) of hydraulic pump P2 (process 65b).

[0075] Through the above processing, the control command values ​​for the electronic valve or hydraulic pumps P1 and P2 related to MC control are corrected in conjunction with the manual inter-operation during MC control, and after the operation related to the manual inter-operation (swinging in the above example) is executed according to the operator's operation, MC control is executed in parallel. Regarding this MC control, it is determined whether the required flow rate can be supplied to the second hydraulic actuator related to MC control even if the supply flow rate to the third hydraulic actuator related to the inter-operation is subtracted; if it appears that no shortage will occur, the target speed of the second hydraulic actuator is output as required, and if it appears that a shortage will occur, the target speed of the second hydraulic actuator is limited and corrected.

[0076] Therefore, if manual operations such as slewing operations are not intervened during MC control (or even if intervened operations are present, if the total required flow rate falls within the maximum discharge flow rate Qmax of the hydraulic pump), there is no effect on the target speeds of the first hydraulic actuator and the second hydraulic actuator regarding MC control. Even if, as a result of manual operations such as slewing operations being intervened during MC control, for example, the target speed of the arm cylinder (32) (second hydraulic actuator) is corrected, the target speed of the boom cylinder (31) (first hydraulic actuator) is calculated according to the target speed of the arm cylinder (32), so the trajectory of the bucket (23) does not change and does not affect the precision of MC control.

[0077] FIG. 6 is a diagram illustrating an example of the trend of the target flow rate Qp2 of the hydraulic pump P2 and the target flow rate Q2 of the arm cylinder (32) that is included in the case where a slewing operation is interposed during MC control in the present embodiment. As shown in the figure, when no slewing operation is combined during MC control, the supply flow rate Q3 to the slewing motor (34) is 0, and since all of the discharge fluid of the hydraulic pump P2 can be supplied to the arm cylinder (32), the target flow rate Qp2 of the hydraulic pump P2 corresponds to the target flow rate Q2 of the arm cylinder (32). However, thereafter, when a slewing operation is combined during MC control and a supply flow rate Q3 to the slewing motor (34) occurs, if the supply flow rate Q3 is simply added to the target flow rate Q2 of the arm cylinder (32), the total flow rate exceeds the maximum discharge flow rate Qmax of the hydraulic pump P2, and there is a possibility that the actual arm speed will not be as the control command value. In addition, there is a possibility that the slewing operation will not produce a speed according to the operator's operation.

[0078] In this embodiment, even if the supply flow rate Q3 to the slewing motor (34) increases, the target flow rate Q2 of the arm cylinder (32) is limited by the difference between the maximum discharge flow rate Qmax and the supply flow rate Q3, so that the total flow rate including the supply flow rate Q3 to the slewing motor (34) does not exceed the maximum discharge flow rate Qmax of the hydraulic pump P2, by correcting the target speed of the arm cylinder (32) described above. Therefore, after securing the slewing operation according to the operator's operation, the actual speed of the arm (22) can be matched to the control command value.

[0079] -effect-

[0080] In this embodiment, when a hydraulic actuator (e.g., a slewing motor (34)) that is not subject to MC control is combined with manual operation during MC control, even if the total required flow rate of the manually operated hydraulic actuator and the hydraulic actuator (e.g., an arm cylinder (32)) connected to the same flow path as the hydraulic actuator exceeds the maximum discharge flow rate of the corresponding hydraulic pump (e.g., hydraulic pump P2), the flow rate available for use in MC control is limited to the flow rate difference Qd obtained by subtracting the required flow rate of the manually operated hydraulic actuator from the maximum discharge flow rate. By doing so, the target speed of the MC-controlled hydraulic actuator (e.g., an arm cylinder (32)) is appropriately corrected, and the distribution of the flow rate of the MC-controlled hydraulic actuator and the manually operated hydraulic actuator can always be determined within the range of the maximum discharge flow rate Qmax of the hydraulic pump. Therefore, for example, by combining the discharge fluid of hydraulic pump P1 with the discharge fluid of hydraulic pump P2, the separation and merging of flow paths increase, which does not lead to a decrease in the precision of MC control. Furthermore, it is possible to avoid a situation where flow is not distributed to each hydraulic actuator according to the control command value when the total required flow rate of each hydraulic actuator reaches the maximum discharge flow rate of the hydraulic pump. Regarding manual operations combined during MC control, since the flow rate corresponding to the amount of operation is supplied to the target hydraulic actuator, the target hydraulic actuator is driven according to the operator's manual operation.

[0081] According to the above embodiment, even when a hydraulic actuator that is not subject to MC control is manually operated during MC control, it is possible to suppress the deterioration of MC control precision while ensuring good responsiveness to manual operation intended by the operator.

[0082] (Second embodiment)

[0083] FIG. 7 is a schematic diagram illustrating the logic of MC control by a controller equipped in a construction machine according to a second embodiment of the present invention, and FIG. 8 is a functional block diagram illustrating the details of the processing of the target speed calculation of FIG. 7. In FIG. 7 and FIG. 8, elements identical to or corresponding to the first embodiment are given the same reference numerals as in the prior drawings, and descriptions are omitted.

[0084] The difference between this embodiment and the first embodiment is that the controller (50) has a function to estimate the actual speed of the second hydraulic actuator based on the output of a detector (e.g., angle detector D2) that detects the operation of a driven member (e.g., arm (22)) driven by the second hydraulic actuator (e.g., arm cylinder (32)), and to correct the target flow rate Q2 of the second hydraulic actuator so that the calculated actual speed matches the target speed of the second hydraulic actuator.

[0085] In this embodiment, the controller (50) calculates an estimated value of the driving speed (estimated actual arm speed) regarding the actual extension or contraction of the arm cylinder (32) based on the change in time of the detection signal (arm angle) input from the angle detector D2 (process 63f). As shown in FIG. 8, the target speed v2 (arm target speed) of the arm cylinder (32) calculated in process 63d is corrected by feedback control based on the estimated actual arm speed, and the corrected target speed v2' is output (process 63g), and the target flow rate G2 is calculated based on the corrected target speed v2' in the process of target flow rate calculation (64) (Fig. 7). Although FIG. 8 illustrates an example where the target speed v1 of the boom cylinder (31) is calculated based on the target speed v2 as in the first embodiment, it may be configured to be calculated based on the corrected target speed v2.

[0086] In other respects, this embodiment is the same as the first embodiment.

[0087] According to the above configuration, in addition to the same effect as in the first embodiment, the difference between the target speed v2 and the actual speed of the second hydraulic actuator (in this example, the arm cylinder (32)) can be reduced by feedback control. Therefore, the precision of MC control can be further improved.

[0088] (Third embodiment)

[0089] FIG. 9 is a functional block diagram illustrating the details of the processing of target speed calculation by a controller equipped in a construction machine according to a third embodiment of the present invention, and is a drawing corresponding to FIG. 4 or FIG. 8. In FIG. 9, elements identical or corresponding to the first or second embodiment are given the same reference numerals as in the previously published drawings, and descriptions are omitted.

[0090] The difference between this embodiment and the first and second embodiments is that the controller (50) has a function to limit the increase in the target speed v2 of the second hydraulic actuator (e.g., arm cylinder (32)) accompanying the decrease in the supply flow rate Q3 of hydraulic fluid from the second hydraulic pump (e.g., hydraulic pump P2) to the third hydraulic actuator (e.g., slewing motor (34)).

[0091] In this embodiment, the corrected target speed v2' calculated in process 63g is output through a low-pass filter (process 63h), and as the signal waveform becomes uniform, it is sent to the processing of the target flow rate calculation (64) (Fig. 7) as a target speed v2" with limited increase. Fig. 9 illustrates an example using a low-pass filter in process 63h, but a rate limiter that limits the increase rate may also be used. Furthermore, while the example in Fig. 9 illustrates an embodiment in which process 63h is applied to the second embodiment, it may also be an embodiment in which process 63h is applied to the first embodiment (i.e., an embodiment in which processes 63f and 63g are omitted). The target speed v1 of the boom cylinder (31) is shown in Fig. 9 as being calculated based on the target speed v2, similar to the first and second embodiments, but it may also be configured to be calculated based on the corrected target speed v2' or v2".

[0092] In other respects, this embodiment is the same as the first embodiment.

[0093] According to the above configuration, in addition to the same effect as in the first or second embodiment, when manual operation is released or the amount of operation is reduced from a state in which manual operation is combined during MC control, the amount of flow that can be supplied to the hydraulic actuator (e.g., arm cylinder (32)) for MC control increases rapidly due to the reduction of the supply flow rate Q3 to the hydraulic actuator (third hydraulic actuator) for manual operation, thereby suppressing the target speed v2 of the hydraulic actuator for MS control, and further, the actual speed.

[0094] Accordingly, according to the present embodiment, even in cases where the difference between the target speed v2' of the arm cylinder (32) calculated in processing 63g and the estimated actual speed of the arm cylinder (32) increases rapidly in a short period of time, the rapid speed change of the arm (22) is prevented, thereby suppressing the operator's discomfort caused by the shock of the machine due to the rapid speed change. In addition, the effect of suppressing the decrease in precision of MC control is also obtained, which is caused by the speed change of the boom (21), which is heavier than the arm (22) and has a strong influence of inertia, not following the rapid speed change of the arm (22).

[0095] As a specific situation in which the difference between the target speed v2' of the arm cylinder (32) and the estimated actual speed increases rapidly in a short period of time, the case where a slewing operation interrupted during MC control is released is exemplified. When the operator stops the slewing operation, the upper limit speed v2u recovers to a value allowed at the maximum discharge flow rate Qmax of the hydraulic pump P2, so the target speed v2 of the arm cylinder (32) increases. Meanwhile, at the moment the upper limit speed v2u is recovered, the estimated actual speed of the arm cylinder (32) remains the same as the speed during the combination with the slewing operation due to the response delay. Therefore, the difference between the target speed v2' of the arm cylinder (32) and the estimated actual speed increases rapidly in an instant. Such a situation may occur, for example, when the slewing operation goes from a maximum amount of operation to no operation (0), from a maximum amount of operation to a fine operation (when the amount of operation decreases), or from an intermediate amount of operation smaller than the maximum amount of operation to no operation (0), as shown in FIG. 10.

[0096] (Variation Example)

[0097] In each of the above embodiments, in relation to the description in the claims, hydraulic pump P1 corresponds to the first hydraulic pump, hydraulic pump P2 corresponds to the second hydraulic pump, boom cylinder (31) corresponds to the first hydraulic actuator, arm cylinder (32) corresponds to the second hydraulic actuator, and slewing motor (34) corresponds to the third hydraulic actuator. However, this example is not limited to this example. For example, as an example of a hydraulic actuator corresponding to the third actuator, in addition to the slewing motor (34), a bucket cylinder (33), or a hydraulic actuator mounted on an attachment such as a positioning cylinder or a tilt rotator may also be applicable.

[0098] For example, in MC control where the movement of the arm (22) and boom (21) is controlled by arm operation, it is not limited to slewing operation, but may also involve bucket operation. In this case, the hydraulic actuator that shares a hydraulic source with the bucket cylinder (33) is the boom cylinder (31), and in relation to the description in the claim, hydraulic pump P2 corresponds to the first hydraulic pump, hydraulic pump P1 corresponds to the second hydraulic pump, the arm cylinder (32) corresponds to the first hydraulic actuator, the boom cylinder (31) corresponds to the second hydraulic actuator, and the bucket cylinder (33) corresponds to the third hydraulic actuator. In this case, based on the output of the angle detector D3 (sensor), the supply flow rate Q3 of hydraulic fluid from the hydraulic pump P1 (second hydraulic pump) to the bucket 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 cylinder (33) (third hydraulic actuator), the upper limit speed v1u of the boom cylinder (31) (second hydraulic actuator) that can be output as the flow rate difference Qd is calculated. The upper speed limit v1u is compared with the required speed of the boom cylinder (31) (second hydraulic actuator) according to the operation signal of the operation device L2 regarding the operation (arm operation) of the front work device (20). If the required speed is less than or equal to the upper speed limit v1u, the required speed is calculated as the target speed v1 of the boom cylinder (31) (second hydraulic actuator), and if the required speed exceeds the upper speed limit v1u, the upper speed limit v1u is calculated as the target speed v1. In this way, when the target speed v1 of the boom cylinder (31) is limited, it is also possible to calculate the target speed v2 of the arm cylinder (32) inversely from the target speed v1 of the boom cylinder (31).

[0099] Additionally, although the case of calculating the supply flow rate Q3 to the third hydraulic actuator (e.g., slewing motor (34)) based on the output of the angle detector (e.g., angle detector D4) has been exemplified, the configuration may also be such that the supply flow rate Q3 is calculated based on the amount of operation of the corresponding operating device (e.g., operating device (L4)).

[0100] In each of the above embodiments, an example in which an electric lever device is employed in the operating devices L1 to L4 has been described; however, the operating devices L1 to L4 may also employ a pilot operation type in which the pilot valve is mechanically operated by an operating lever. When the operating devices L1 to L4 are of the pilot operation type, a pilot pressure is generated by using the pressure of the pilot primary pressure line PL3 as the source pressure by a pilot valve (pressure reducing valve) that is mechanically linked with the operating lever, and the directional control valves V1 to V4 are driven by the pilot pressure. At that time, for example, solenoid valves Sn1 and Sn2 for MC control are provided between the pilot valve and the corresponding directional control valve, or between the pilot pump P3 and the directional control valve by bypassing the pilot valve. As for the amount of lever operation, the configuration may be such that the pilot pressure output by the pilot valve is detected by a pressure sensor, or the configuration may be such that the amount of lever operation itself is detected by a potentiometer or the like.

[0101] In addition, although an example was described in which the actual value of the turning speed is estimated based on the output of the angle detector D4 in the second or third embodiment, an angular velocity sensor that directly detects the angular velocity of the turn may also be used. Furthermore, it is also conceivable to estimate the turning speed from the amount of turning operation. Additionally, to prepare for sensor failure, a configuration combining multiple of these methods may be used.

[0102] In addition, although an example has been described of calculating the attitude of the front work device (20) based on the output of angle detectors D1-D3, a stroke sensor (wire type, wheel type, etc., the method does not matter) that detects the stroke of a hydraulic cylinder may also be used. Alternatively, the configuration may be configured to calculate the attitude of the front work device (20) based on the output of an acceleration sensor, such as an IMU, that detects the angle of a driven member, such as a boom (21), relative to the direction of gravity. Furthermore, to prepare for sensor failure, a configuration combining multiple of these methods may also be used. Explanation of the symbols

[0103] 10: Vehicle body, 12: Slewing body (driven member), 20: Front implement, 31: Boom cylinder (1st hydraulic actuator), 32: Arm cylinder (2nd hydraulic actuator), 34: Slewing motor (3rd hydraulic actuator), 50: Controller, Dn: Angle detector (sensor, detector), Ln: Operating device, P1: Hydraulic pump (1st hydraulic pump), P2: Hydraulic pump (2nd hydraulic pump), Vn: Direction change valve, Sn1, Sn2: Solenoid valve

Claims

Claim 1 A vehicle body, a front work device installed on the vehicle body, a first hydraulic pump and a second hydraulic pump mounted on the vehicle body, a first hydraulic actuator driven by the discharge path of the first hydraulic pump to drive the front work device, a second hydraulic actuator driven by the discharge path of the second hydraulic pump to drive the front work device, a third hydraulic actuator driven by the discharge path of the second hydraulic pump, a directional control valve that controls the flow of hydraulic fluid from the second hydraulic pump to the second hydraulic actuator, an electronic valve that generates a pilot pressure to drive the directional control valve, an operating device for operating the front work device, a sensor that detects the amount of angle change of a driven member driven by the third hydraulic actuator corresponding to the operation of the third hydraulic actuator, or the amount of operation of the third hydraulic actuator, a target surface distance which is the distance between a specific point of the front work device and a preset target construction surface, and an operation signal according to the operation of the operating device In a construction machine equipped with a controller that controls the electronic valve, the first hydraulic pump, and the second hydraulic pump, the controller calculates the supply flow rate of hydraulic fluid from the second hydraulic pump to the third hydraulic actuator based on the output of the sensor, calculates the upper limit speed of the second hydraulic actuator based on the difference between the maximum flow rate that the second hydraulic pump can discharge and the supply flow rate to the third hydraulic actuator, compares the required speed of the second hydraulic actuator according to the operation signal with the upper limit speed, calculates the required speed as the target speed of the second hydraulic actuator if the required speed is less than or equal to the upper limit speed, calculates the upper speed as the target speed if the required speed exceeds the upper limit speed, and calculates the target flow rate of the second hydraulic pump by adding the supply flow rate to the third hydraulic actuator to the flow rate according to the target speed of the second hydraulic actuator.A construction machine characterized by controlling the electronic valve based on the above target speed and controlling the second hydraulic pump based on the above target flow rate. Claim 2 delete Claim 3 A construction machine according to claim 1, comprising a detector for detecting the operation of a driven member driven by the second hydraulic actuator, wherein the controller calculates the actual speed of the second hydraulic actuator based on the output of the detector and corrects the target flow rate so that the actual speed matches the target speed. Claim 4 A construction machine according to claim 1, wherein the controller limits the increase in the target speed accompanying the decrease in the supply flow rate of hydraulic fluid from the second hydraulic pump to the third hydraulic actuator to a predetermined value.

Images