JP3329506B2 - Hydraulic construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic construction machine such as a hydraulic excavator, and more particularly to a hydraulic construction machine including at least two hydraulic pumps, a traveling actuator and a work actuator (front actuator), and load sensing for two hydraulic pumps. The present invention relates to a hydraulic construction machine that performs control and input torque limiting control.

[0002]

2. Description of the Related Art As a conventional hydraulic construction machine control method,
A pump regulator of a load sensing control (hereinafter referred to as LS control as appropriate) system for controlling the pump discharge flow rate in response to the maximum load pressure of the actuator so that the pump discharge pressure becomes higher than the maximum load pressure of the actuator by a predetermined value is provided. Are known, examples of which are described in the following documents.

JP-A-2-118203; JP-A-2-248706; JP-A-3-024302; JP-A-3-249412; JP-A-1-316502; JP-A-2-279829. JP-A-3-082044 and the like.

[0004] In the literature, a hydraulic drive device controlled by one pump LS is described. That is, the hydraulic drive device includes one hydraulic pump, a plurality of actuators driven by pressure oil discharged from the one hydraulic pump, and a regulator having an LS control function for the one pump. All the actuators are driven by LS control of one of the hydraulic pumps. Also,
The pump regulator also has an input torque limiting function that controls the pump discharge flow rate to decrease as the pump discharge pressure increases, and reduces the load on the prime mover that drives the hydraulic pump.

[0005] Documents 1 to 3 disclose a hydraulic drive device controlled by two pumps LS. That is, the hydraulic drive device includes two hydraulic pumps, a plurality of actuators driven by pressure oil discharged from the two hydraulic pumps, and a regulator having an LS control function for each of the two hydraulic pumps. The actuator is driven by LS controlling the two hydraulic pumps, and the hydraulic oil discharged from the two hydraulic pumps is joined or separated to improve the working efficiency. The pump regulator has an input torque limiting control function as described above. The plurality of actuators include a plurality of front actuators and left and right travel motors, and one of the left and right travel motors and a part of the front actuator correspond to one pump, and the other travel motor and the rest of the front actuators Correspond to the other pump. The reason why the left and right traveling motors correspond to the respective pumps is to secure a steering force. In other words, during steering, the difference between the load pressures of the left and right traveling motors becomes large. Therefore, dividing the pumps by the left and right traveling motors ensures the independence of the flow rate of the pressure oil supplied to the left and right traveling motors. This is because it is easy to give a large steering force.

[0006]

In the prior art described in the above-mentioned document, since one pump LS control method is used, when the difference between the load pressures of a plurality of actuators is large in a combined operation of simultaneously driving a plurality of actuators, However, the discharge flow rate of the hydraulic pump is governed by the load pressure on the high pressure side by the input torque limiting control, so that the total flow rate is insufficient and the work efficiency is poor.

[0007] To solve the above problem, the prior art described in the literature employs two-pump LS control, and improves or improves the working efficiency by merging or separating the hydraulic oil discharged from the two hydraulic pumps. I'm trying. However, in actual work of a hydraulic excavator, a problem caused by a difference between a high pressure and a low load pressure is a combined operation of traveling and front work. That is, according to the prior art described in the literature: (1) In the uphill traveling complex, the load pressure of the traveling motor is increased, the pump flow rate is reduced by the input torque limiting control, and the front does not rise.

(2) When escaping from mud, the load pressure of the front actuator becomes extremely higher than the load pressure of the traveling motor in order to obtain the pulling force of the arm. Due to the increase in the pressure of the front actuator, the input torque limiting control works to reduce the pump discharge flow rate, so that the entire operation including traveling is slowed down, and the vehicle cannot escape. On the other hand, if the characteristics of the flow control valve (control valve) are changed so that the flow rate of the pressure oil flowing from the high pressure side to the low pressure side is increased, a large amount of pressure oil flows to the traveling motor, and the driving force of the front actuator is reduced. And cannot escape.

In the prior arts described in Documents (1) and (2), the pumps are divided by the left and right traveling motors, so that the above problems (1) and (2) cannot be solved.

A first object of the present invention is to provide a hydraulic construction machine capable of improving the combined operability of traveling and front work.

A second object of the present invention is to provide a hydraulic construction machine that improves traveling combined operability without impairing steering performance in traveling alone.

[0012]

In order to achieve the first object, the present invention provides at least two hydraulic pumps,
A plurality of hydraulic actuators driven by pressure oil discharged from the two hydraulic pumps, a flow control valve for controlling a flow of the pressure oil supplied to the plurality of hydraulic actuators, respectively, and each of the two hydraulic pumps Pump control means for controlling the discharge flow rate of the pump so that the pump discharge pressure is higher than the maximum load pressure of the hydraulic actuator driven by each hydraulic pump; and the pump discharge flow rate is increased when the pump discharge pressure is increased. A second pump control means for controlling a discharge flow rate of each of the two hydraulic pumps so as to reduce the pressure, wherein the plurality of actuators includes at least one front actuator and at least one travel actuator. (A) a second actuator including the front actuator and its flow control valve; Hydraulic circuit and the driving actuator and the second hydraulic circuit including the flow control valve; (b)
A first position installed between the two hydraulic pumps and the first and second hydraulic circuits and connecting the two hydraulic pumps to at least the first hydraulic circuit; A second which preferentially connects one to the first hydraulic circuit and the other preferentially connects to the second hydraulic circuit;
(C) moving the valve means to the first position when only the front actuator is operated, and the valve means when the front actuator and the travel actuator are operated simultaneously. And a merging control means having a function of moving the second position to the second position.

In the specification of the present application, "priority connection" means that the valve means takes the "fully closed position" with respect to the connection with the other hydraulic circuit, and "partially open position", that is, "throttle position". Is used.

In the above hydraulic construction machine, preferably
One of the two hydraulic pumps is connected to the first hydraulic circuit via a first supply line, and the other is connected to the second hydraulic circuit via a second supply line, The first and second supply lines are connected to each other via a merging line, and the valve means includes a merging separation valve disposed in the merging line .

According to another aspect of the present invention, in the hydraulic construction machine, the travel actuator includes left and right travel actuators, and the second hydraulic circuit includes the right travel actuator and the right travel actuator. A third hydraulic circuit including a flow control valve, a fourth hydraulic circuit including the left travel actuator and its flow control valve,
The valve means further includes a third position where one of the two hydraulic pumps is preferentially connected to the third hydraulic circuit, and the other is preferentially connected to the fourth hydraulic circuit. The control means moves the valve means to the third position when only the travel actuator is operated.

In the above hydraulic construction machine, preferably,
One of the two hydraulic pumps is connected to the first hydraulic circuit via a first supply line, and the other is connected to the third hydraulic circuit via a second supply line, The fourth hydraulic circuit has a third supply line for supplying pressure oil to the fourth hydraulic circuit, and the third supply line is connected to the first supply line and a first junction pipe. And a valve connected to the second supply line via a second merging line, wherein the valve means includes a first merging separation valve disposed in the first merging line and the first merging separation valve. A second merging separation valve disposed in the second merging line.

Preferably, the hydraulic construction machine preferably includes a first differential pressure detecting means for detecting a differential pressure between a supply pressure of the first hydraulic circuit and a load pressure of the front actuator; And a second differential pressure detecting means for detecting a differential pressure between a supply pressure of a circuit and a load pressure of the travel actuator, wherein the first pump control means controls the valve means to move to the first position. When the first
Controlling the discharge flow rates of the two hydraulic pumps based on the differential pressure detected by the differential pressure detecting means, and when the valve means is moved to the second position, the first differential pressure detecting means The control unit controls the discharge flow rate of one of the two hydraulic pumps based on the differential pressure detected by the control unit, and controls the discharge flow rate of the other based on the differential pressure detected by the second differential pressure detection unit.

[0018] The hydraulic construction machine is more preferably
First differential pressure detecting means for detecting a differential pressure between a supply pressure of the first hydraulic circuit and a load pressure of the front actuator, a supply pressure of the third hydraulic circuit, a load pressure of the right travel actuator, And a third differential pressure detecting means for detecting a differential pressure between the supply pressure of the fourth hydraulic circuit and the load pressure of the left traveling actuator. The first pump control means, when the valve means is moved to the first position,
The discharge flow rates of the two hydraulic pumps are respectively controlled based on the differential pressure detected by the first differential pressure detection means, and when the valve means is moved to the second position, the first flow rate is set to the first position.
The discharge flow rate of one of the two hydraulic pumps based on the differential pressure detected by the differential pressure detecting means, and the other based on the smaller of the differential pressures detected by the second and third differential pressure detecting means. When the valve means is moved to the third position, the discharge flow rate of one of the two hydraulic pumps is controlled based on the differential pressure detected by the second differential pressure detecting means. Is controlled on the basis of the differential pressure detected by the third differential pressure detecting means.

The hydraulic construction machine preferably comprises:
The apparatus further includes operation detection means for detecting operations of the front actuator and the travel actuator, wherein the merge control means determines whether the front actuator and the travel actuator are simultaneously operated based on a signal from the operation detection means. Judge.

[0020]

According to the first aspect of the present invention, when only the front work is performed, the merging control means moves the valve means to the first position. When the valve means is moved to the first position, 2
One hydraulic pump is connected to at least the first hydraulic circuit. Thereby, the pressure oil discharged from the two hydraulic pumps is supplied to the first hydraulic circuit, and only the front work can be performed. When performing a combined operation of traveling and front work, the merging control means moves the valve means to the second position. When the valve means is moved to the second position, one of the two hydraulic pumps is preferentially connected to the first hydraulic circuit and the other is preferentially connected to the second hydraulic circuit. This allows
At least most of the pressure oil discharged from one hydraulic pump is supplied to the first hydraulic circuit, and at least most of the pressure oil discharged from the other hydraulic pump is supplied to the second hydraulic circuit. The independence of the flow rate of the pressure oil supplied to the traveling actuator and the front actuator is ensured, and the traveling combined operability is improved.

For example, in an uphill traveling complex, the input torque limiting control acts on the hydraulic pump that drives the traveling actuator, and even if the pump discharge flow rate is reduced, the hydraulic pump that drives the front actuator is not affected by the load pressure. Since the pressure oil is supplied without receiving it, the front can be raised higher.

Also, when the mud is escaped, the load pressure of the front actuator becomes extremely higher than the load pressure of the traveling motor in order to obtain the pulling force of the arm, and the input torque to the hydraulic pump driving the front actuator is reduced. Even if the limit control is activated and the pump discharge flow rate decreases, the hydraulic pump that drives the travel actuator supplies pressure oil without being affected by the load pressure, so the drive power of the travel motor can be obtained and the mud can escape. it can.

Further, in the present invention according to the second object, when performing the traveling alone operation, the merging control means moves the valve means to the third position. When the valve means is moved to the third position, one of the two hydraulic pumps is preferentially connected to the third hydraulic circuit and the other is preferentially connected to the fourth hydraulic circuit. As a result, the hydraulic oil discharged from one hydraulic pump is supplied to the third hydraulic circuit, and the hydraulic oil discharged from the other hydraulic pump is supplied to the fourth hydraulic circuit. Independence of the flow rate of the pressure oil supplied to the travel actuator is ensured, and a large steering force can be exerted at the time of a steering operation such as a large turning travel and a spin turn, and excellent steering performance can be obtained.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. In this embodiment, the present invention is applied to a hydraulic excavator.

In FIGS. 1 and 2, the control device relating to the hydraulic shovel of this embodiment includes two variable displacement hydraulic pumps driven by a prime mover (not shown), ie, main pumps 200R and 200L, and main pumps 200R and 200R. 200L
Actuators driven by pressure oil discharged from the motor, ie, right running motor 23, left running motor 24, swing motor 25, boom cylinder 26, arm cylinder 2
7, and a flow control valve for controlling the flow of the hydraulic oil supplied to each of the bucket cylinder 28 and the plurality of actuators, that is, the right traveling direction switching valve 29, the left traveling direction switching valve 30, the turning direction switching. A valve 31, a boom directional switching valve 32, an arm directional switching valve 33, and a bucket directional switching valve 34, which are respectively arranged upstream thereof in correspondence with these flow control valves, and between the inlet and the outlet of the flow control valve. The resulting differential pressure, that is, the differential pressure ΔPv1, ΔPv2, ΔP across the flow control valve
v3, ΔPv4, ΔPv5, ΔPv6 are respectively controlled by pressure compensating valves, that is, branching compensating valves 35, 36, 37, 38, 39,
40.

As shown in FIGS. 3 and 4, the right running motor 23 and the left running motor 24 drive the footwear of the excavator, that is, the running bodies 2 and 3, and the turning motor 25 drives the turning body 1 of the excavator. Then, the boom cylinder 26, the arm cylinder 27, and the bucket cylinder 28 drive the boom 4, the arm 5, and the bucket 6, which are front mechanisms of the hydraulic shovel, respectively. Since the swing motor 25, the boom cylinder 26, the arm cylinder 27, and the bucket cylinder 28 are used to operate the hydraulic excavator by moving the front mechanism, they are collectively referred to as a front actuator in this specification.

Referring back to FIGS. 1 and 2, the front actuators 25 to 28, their flow control valves 31 to 34, and the diversion compensating valves 37 to 40 constitute a first hydraulic circuit 301.
Left and right traveling motors 23, 24 and their flow control valves 2
9, 30 and the diversion compensating valves 35, 36 are connected to the second hydraulic circuit 30.
Constituting No. 2. The second hydraulic circuit 302 has a right traveling motor 23, a third hydraulic circuit 303 having a flow control valve 29 thereof and a diversion compensating valve 35, a left traveling motor 24, a flow control valve 30 thereof, and a diversion compensating valve 36. And a fourth hydraulic circuit 304.

The hydraulic pump 200R is connected to the first supply line 30.
5 is connected to the first hydraulic circuit 301, and the hydraulic pump 200 </ b> L is connected to the third hydraulic circuit 303 via the second supply line 306. In addition, the fourth hydraulic circuit 3
04 has a third supply line 307 for supplying pressure oil to the hydraulic circuit 304, and the third supply line 307 is connected to the first supply line 305 via the first merging line 308. And the second supply line 3 via the second merging line 309.
06. A merging separation valve 500a is arranged in the second merging line 309, and a merging separation valve 500b is arranged in the first merging line 308. These converging / separating valves 500a and 500b are normally open electromagnetic on / off valves that can be switched to two positions of fully open and fully closed by an electric signal output from the controller 61. As will be described later, the merge separation valves 500a and 500b may be valves that can be switched between two positions, that is, fully open and partially open, that is, a throttle position.

Check valves 42a, 42b, 42c, 4 for taking out the load pressures of the flow control valves 29 to 34 when the actuators 23 to 28 are driven are provided respectively.
Load lines 43a, 43 having 2d, 42e, 42f
b, 43c, 43d, 43e, 43f are connected. Among these load lines, the load lines 4 related to the front actuators 25 to 28 of the first hydraulic circuit 301
3c to 43f are connected to a common load line 44 on the output side of the check valves 42c to 42f, and are connected to the load line 44 and the first
Between the supply pressure of the first hydraulic circuit 301 and the highest load pressure (hereinafter referred to as maximum load pressure) PLmax among the load pressures of the front actuators 25 to 28, Differential pressure between both (LS differential pressure) ΔPc
Is connected. The output side of the check valve 42a of the load line 43a related to the right running motor 23 of the third hydraulic circuit 303 and the second supply line 3
06, a differential pressure detector 59a for introducing the supply pressure of the third hydraulic circuit 303 and the load pressure PLrt of the right traveling motor 23 and detecting the differential pressure (LS differential pressure) ΔPa between them is connected. The fourth hydraulic circuit 304 is provided between the output side of the check valve 42b of the load line 43b for the left traveling motor 24 of the fourth hydraulic circuit 304 and the third supply line 307.
And a load pressure PLlt of the left traveling motor 24, and a differential pressure detector 59b for detecting a differential pressure (LS differential pressure) ΔPb therebetween is connected. Differential pressure detectors 59a-59
The signal output from c is input to the controller 61.

The operation levers of the flow control valves 29 to 34 detect the operation of the operation levers and detect the operation of the corresponding actuators 23 to 28.
a, 30a, 31a, 32a, 33a, 34a. The signals output from the operation detectors 29a to 34a are also input to the controller 61.

Each of the branch flow compensating valves 35 to 40 is constructed as follows. The branching compensating valve 35 is guided by the outlet pressure of the right traveling direction switching valve 29 and urges the valve body of the branching compensating valve 35 in the valve opening direction, and the inlet pressure of the right traveling direction switching valve 29. Are driven, a driving unit 35b for urging the valve body of the branch flow compensation valve 35 in the valve closing direction, a spring 45 for biasing the valve body of the branch flow compensation valve 35 in the valve opening direction with the force f, and a pilot line 51a. Control pressure P from the hydraulic pressure generation circuit 65
and a drive unit 35c that guides c1 and urges the valve element of the branch flow compensation valve 35 in the valve closing direction with the control force Fc1. Drive unit 3
5a and 35b apply a first control force to the valve body of the flow dividing compensating valve 35 in the valve closing direction based on the front-rear pressure difference ΔPv1 of the right traveling direction switching valve 29, and the spring 45 and the driving section 35c cause the flow of the flow dividing compensating valve. The second control force f-Fc1 is applied to the valve body 35 in the valve opening direction. The throttle amount of the branching compensation valve 35 is determined by such a balance between the first control force and the second control force,
The differential pressure ΔPv1 between the right and left direction switching valves 23 is controlled. Here, the second control force f-Fc1 is a value for setting a target value (target compensation differential pressure) of the front-rear pressure difference ΔPv1 of the right traveling direction switching valve 23.

The other diversion compensating valves 36 to 40 have the same configuration. That is, the branch flow compensating valves 36 to 40 connect those valve bodies to the differential pressures ΔPv2 to ΔPv across the flow control valves 30 to 34.
opposing driving parts 36a, 36b; 37a, 37b; 38a, 38, each of which is urged by a first control force based on v6.
b; 39a, 39b; 40a, 40b and springs 46, 47, 58, 59, 50 for urging the valve body in the valve opening direction with a force f.
And pilot lines 51b, 51c, 51d, 51
Control pressures Pc2, Pc3, Pc4, Pc5, and Pc6 from the control pressure generating circuit 65 are led through the control valves e and 51f. Drive units 36c, 37c, 38c, 39c, 4
0c.

As shown in FIG. 5, the control pressure generating circuit 65 is provided corresponding to the flow compensating valves 35 to 40, and outputs electric signals a, b, c, d, and
Electromagnetic proportional pressure reducing valves 62a, 62 for inputting e and f, respectively.
b, 62c, 62d, 62e, and 62f, a pilot pump 63 that supplies pilot pressure to the electromagnetic proportional pressure reducing valves 62a to 62f, and a relief valve 64 that regulates the magnitude of the pilot pressure output from the pilot pump 63. The electromagnetic proportional pressure reducing valves 62a to 62f are operated by the electric signals a to f, and the control forces Fc1 to
Control pressures Pc1 to Pc6 corresponding to the value of Fc6 are generated, and are generated via pilot lines 51a to 51f.
It outputs to 5-40 drive parts 35c-40c, respectively.

The discharge flow rate of the main pump 200R is controlled by a pump controller 400R.
Is a tilt drive device 400aR that drives the swash plate of the main pump 200R to increase or decrease the displacement, and an electromagnetic proportional pressure reducing valve 400 that outputs a control pressure to the tilt drive device and drives it.
bR. Similarly, for the main pump 200L, the tilt drive device 400aL and the electromagnetic proportional pressure reducing valve 400b
L is provided with a pump control device 400L. The electromagnetic proportional pressure reducing valves 400bR, 400bL of the pump control devices 400R, 400L are driven by electric signals output from the controller 61, and are driven by the main pumps 200R, 2L.
The discharge flow rates of the main pumps 200R, 200L are controlled such that the discharge pressure Ps of 00L is higher than the maximum load pressure Pamax or PLrt, PLlt of the associated hydraulic circuit by a predetermined value ΔPLSO.

The main pumps 200R and 200L are provided with displacement detectors 223R and 223L for detecting the tilt angle (displacement volume) Qθ of the swash plate of the main pump, respectively, and the first and second supply pipes 305 and 306 are provided. Each has a main pump 2
Pressure detectors 224R and 224L for detecting the discharge pressures Pa and Pb of 00R and 200L (hereinafter, represented by Ps) are provided. These displacement detectors 223R, 223L
The signals output from the pressure detectors 224R and 224L are input to the controller 61. The first and second supply lines 305, 306 are further provided with a main pump 20 respectively.
When the discharge pressure oil of 0R and 200L reaches the relief set pressure, the pressure oil flows out to the tank, and relief valves 300R and 300L for limiting the pump discharge pressure to the set pressure or less are provided. Although not shown, the first and second supply pipes 305 and 306 have unloads for releasing the pressure oil to the tank when the pressure difference between the discharge pressures of the main pumps 200R and 200L and the maximum load pressure becomes equal to or higher than a set pressure. A valve is provided.

The controller 61 is constituted by a microcomputer, and as shown in FIG. 6, operation detectors 29a, 30a, 31a, 32a, 3 for detecting the movement of the operation lever.
3a, 34a, displacement detector 22 for detecting pump tilt angle
3R, 223L, pressure detectors 224R, 224L for detecting pump discharge pressure, differential pressure detector 5 for detecting LS differential pressure
A / D converter 61a for inputting signals from 9a, 59b, 59c and converting them into digital signals, a central processing unit (CPU) 61b, a read-only memory (ROM) 61c for storing control programs, Random access memory (RA) for temporarily storing intermediate values
M) 61d, a D / A converter 61e for converting a digital signal into an analog signal, and merging separation valves 500a, 55
0b, an amplifier (AM) that outputs a drive signal to the electromagnetic proportional pressure reducing valves 400bR, 400bL and the control pressure generating circuit 65.
P) 61f.

FIG. 7 is a block diagram showing the control function of the controller 61. The controller 61 controls the lever operation (operation detectors 29a, 30a, 31a, 32a, 33a, 34).
a), the merge separation valves 500a, 500b
Separation control function 320 for controlling the lever operation, lever operation and L
S differential pressure (signal from differential pressure detector 59a, 59b, 59c), pump tilt angle (signal from displacement detector 223R, 223L) and pump discharge pressure (pressure detector 224R, 2
24L) based on the electromagnetic proportional pressure reducing valve 400a
R, 300aL to control the tilt angle of the main pumps 200R, 200L, and the control pressure generating circuit 65 based on the LS differential pressure to drive the flow dividing compensation valve 3.
And a separate shunt compensation control function 322 for controlling 5 to 40. Programs for executing these functions are stored in the ROM 61c.

The details of the merging / separation control function 320, the pump flow rate control function 321 and the individual branch flow compensation control function will be sequentially described with reference to the drawings.

FIG. 8 is a block diagram showing the merge / separation control function 320. In block 320a, the operation detector 29
a, 30a, 31a, 32a, 33a, 34a, based on the lever operation detected, only the front operations (front actuators 25 to
28); running alone operation (whether only the running motors 24, 24 are operated); running combined operation (whether the front actuators 25 to 28 and the running motors 23, 24 are operated simultaneously). . FIG. 9 shows the above-mentioned operation determination patterns.
NO. Is a pattern number for operation determination , and is 1 to 57. “0” indicates that the actuator is not operated, and “1” indicates that the actuator is operated.

In block 320b, block 32
0a based on the operation determination result at 0a
00b is set, and the merging separation valves 500a and 500b are set.
0b switching is controlled. FIG. 10 shows the switching pattern. When only the front is operated, the merging separation valve 5
00a and 500b are both turned off (open). When only one side of the traveling is operated, the junction separation valve 500a is turned ON (closed), and the junction separation valve 500b is turned OFF (open).
When the operation of both sides is operated alone, the merge separation valve 500
a is turned ON (closed), and the merge separation valve 500b is turned OFF (open). At the time of traveling combined operation, the merge separation valve 500a
Is turned off (open), and the merge separation valve 500b is turned on (closed). As will be described later, the merging separation valve 500a may be turned off (open) when the operation is performed on only one side of traveling alone, and in this case, the merging separation valve 500b is turned on (closed) or off (open). To

FIG. 11 is a block diagram showing the pump flow control function 321. In block 321a, the above-mentioned operation determination shown in FIG. 9 is performed based on the lever operation detected by the operation detectors 29a, 30a, 31a, 32a, 33a, 34a. In block 321b, based on the operation determination result in block 321a, the differential pressure detector 59a,
LS differential pressures ΔPa, ΔPb, detected at 59b and 59c, respectively.
One of ΔPc is set as LS differential pressure ΔPLSL, ΔPLSR used for main pumps 200L, 200R. FIG.
Shows its setting pattern. When only the front is operated, the LS differential pressure Δ
ΔPc is set as PLSL and ΔPLSR. LS of the main pump 200L when the operation of only one side of
The differential pressure ΔPLSL is set to ΔPa, the LS differential pressure ΔPLSR of the main pump 200R is set to ΔPb, and the LS differential pressure ΔP
LSL is set to ΔPa, and the LS differential pressure Δ of the main pump 200R is set.
Set ΔPb in PLSR. LS differential pressure ΔPLSL of the main pump 200L at the time of the traveling composite operation of ΔPa, ΔP
b is set to the minimum value, and the LS differential pressure ΔP of the main pump 200R is set.
ΔPc is set in LSR. When only one side of the traveling is operated, the LS differential pressure ΔP of the main pump 200L is used.
The minimum values of ΔPa and ΔPb may be set in LSL. In this case, the LS differential pressure ΔPLSR of the main pump 200R is ΔPc
Alternatively, any of the minimum values of ΔPa and ΔPb is set.

In the block 321c, the block 321b
The difference between the LS differential pressure .DELTA.PLSL or .DELTA.PLSR set in the step (1) and the preset target differential pressure .DELTA.PLS0 is determined, and the block 32
In 1d, the differential pressure deviation ΔPLS0 is multiplied by the integral gain KI to obtain an increment ΔQΔP of the differential pressure target pump tilt angle. In a block 321e, the target pump tilt angle Q0-1 one cycle before is added to the increment ΔQΔP. A target pump tilt angle QΔP for LS control is obtained. That is, block 32
1c to 321e, the target pump tilt angle Q by the integral control method
Find ΔP. Note that a proportional control method may be used instead of the integral control method, or both the integral control method and the proportional control method may be used.

On the other hand, in block 321f, a target pump tilt angle QT for input torque limiting control is obtained from the pump discharge pressure Ps detected by the pressure detectors 224R and 224L based on a preset functional relationship.

In block 321g, the target pump tilt angle Q
The smaller value of ΔP and the target pump tilt angle QT is selected and set as the commanded target pump tilt angle Q0. In block 321h, the command target pump tilt angle Q0 and the displacement detector 223 are set.
A deviation from the tilt angle Qθ of the main pump 200R or the tilt angle Qθ of the main pump 200L detected by R or 223L is obtained, and a signal corresponding to the deviation is used as a drive signal to set the electromagnetic proportional pressure-reducing valve 400bR of the main pump 200R or Output to the electromagnetic proportional pressure reducing valve 400bL of the main pump 200L. As a result, the main pumps 200L and 200R
When the target pump tilt angle QΔP is selected at 1 g, the LS control is performed so that the pump discharge pressure becomes higher than the maximum load pressure by the target differential pressure ΔPLS0, and the target pump tilt angle QT
Is selected, input torque limiting control is performed so that the pump discharge flow rate decreases as the pump discharge pressure increases.

FIG. 13 is a block diagram showing the individual shunt compensation control function 322. In this function 322, the LS differential pressure ΔP detected by the differential pressure detectors 59a, 59b, 59c
By using a, ΔPb, and ΔPc, a branching characteristic calculation is performed for the branching compensation valves 35 to 40, and drive signals a to f are output to the control pressure generation circuit 65. That is, the blocks 74a to 74a
4f, the relationship between the differential pressure ΔPLS and the control forces Fc1 to Fc6 is set in advance. In the block 74a of the third hydraulic circuit 303 related to the shunt compensation valve 35, the LS differential pressure detected by the differential pressure detector 59a is detected. The corresponding control force Fc1 is calculated using ΔPa, and in the block 74b of the fourth hydraulic circuit 304 related to the branching compensation valve 36, the Lf detected by the differential pressure detector 59b is used.
The corresponding control force Fc2 is calculated using the S differential pressure ΔPb,
In the blocks 74c to 74f related to the pressure compensating valves 37 to 40 of the first hydraulic circuit 301, the corresponding control forces Fc3 to Fc are determined using the LS differential pressure ΔPc detected by the differential pressure detector 59c.
c6 is calculated individually. These control forces Fc1 to Fc6 are output as drive signals a to f after being subjected to first-order lag element filtering in delay blocks 76a to 76f.

The drive signals a to f drive the electromagnetic proportional pressure reducing valves 62a to 62f of the control pressure generating circuit 65, and the control force Fc1 to the control force Fc1.
The control pressure Pc1-Pc6 corresponding to Fc6 is changed to the shunt compensation valve 35-
Forty drive units 35c to 40c are output. Drive unit 35c
The control pressures Fc1 to Fc6 apply control forces Fc1 to Fc6 in the valve closing direction to the diversion compensating valves 35 to 40 by the control pressure.
To 40, the second control forces f-Fc1, f-Fc2, f-Fc
3, f-Fc4, f-Fc5, and f-Fc6 are provided in the valve opening direction, and individual diversion compensation characteristics are given to the diversion compensation valves 35 to 40.

Relationship between differential pressure ΔPLS set in function blocks 74a to 74f and control forces Fc1 to Fc6, and delay block 7
For details of the primary transfer elements 6a to 76f and the individual shunt compensation control obtained therefrom, see WO 90/1374.
No. 8, which is not described here.

The configuration of the above embodiment is summarized as follows. The merge separation valves 500a and 500b are installed between the two hydraulic pumps 200R and 200L and the first and second hydraulic circuits 301 and 302, and connect the two hydraulic pumps to at least the first hydraulic circuit 301. Valve means having a first position and a second position where one of the two hydraulic pumps 200R is preferentially connected to the first hydraulic circuit 301 and the other 200L is preferentially connected to the second hydraulic circuit 302. And the merging / separation control function 32 of the controller 61
0 is based on the signals from the operation detectors 29a to 34a and the front actuators 25 to 28 and the traveling motors 23, 2
4 is operated at the same time, and when it is determined that only the front actuator is operated, the valve means is moved to the first position. When it is determined that the front actuator and the travel actuator are simultaneously operated, Confluence control means for moving the valve means to the second position is provided.

The valve means constituted by the merge separation valves 500a and 500b is provided with one of two hydraulic pumps 200
L to the third hydraulic circuit 303 preferentially,
It further has a third position where OR is preferentially connected to the fourth hydraulic circuit 304, and the merging control means constituted by the merging / separation control function 320 determines that only the traveling motors 23 and 24 have been operated. Sometimes the valve means is moved to the third position.

On the other hand, in the controller 61, the blocks 321c to 321h of the pump flow rate control function 321 are controlled by the two hydraulic pumps 200R and 200R so that the pump discharge pressure is higher than the maximum load pressure of the plurality of actuators.
L constitutes first pump control means for controlling the discharge flow rate of each of the pumps L.
1f, 321g and 321h are two hydraulic pumps 200 so that the pump discharge flow rate decreases as the pump discharge pressure increases.
The second pump control means for controlling the discharge flow rates of R and 200L is constituted.

Block 32 of pump flow control function 321
When the valve means is moved to the first position, the first pump control means composed of two hydraulic pumps 200R based on the differential pressure ΔPc detected by the differential pressure detector 59c. , 200L respectively, and when the valve means is moved to the second position, the discharge flow rate of one of the two hydraulic pumps 200R is determined based on the differential pressure ΔPc detected by the differential pressure detector 59c. , Based on the differential pressure ΔPa or ΔPb detected by the differential pressure detector 59a or 59b, respectively.

When the valve means is moved to the first position, the first pump control means controls the two hydraulic pumps 200R and 200L based on the differential pressure ΔPc detected by the differential pressure detector 59c. Control the discharge flow rate of
When the valve means is moved to the second position, the discharge flow rate of one of the two hydraulic pumps 200R is determined based on the differential pressure ΔPc detected by the differential pressure detector 59c.
a, based on the smaller of the differential pressures ΔPa, ΔPb detected at 59b, respectively, to control the discharge flow rate of the other 200L,
When the valve means is moved to the third position, the discharge flow rate of one of the two hydraulic pumps 200R is determined based on the differential pressure ΔPb detected by the differential pressure detector 59b.
Based on the differential pressure ΔPa detected in a, the discharge flow rate of the other 200 L is controlled.

Next, the operation of this embodiment configured as described above will be described. The operation is described in the following (1) to
The operation example of (4) is given, and these are described in the following (A) to (E).
Will be described in the following order.

[Examples of operation] (1) Front operation alone (excavation work, loading work, etc.) (2) Traveling single-sided operation (pipot turn) (3) Traveling single-sided operation (straight running, large bend running, spin turn, etc.) (4) Combined traveling operation (combined climbing traveling operation, escape operation of mud, etc.) [Sequence of explanation] (A) Operated flow control valve (B) Operation of merge separation valves 500a and 500b (C) Main pump 200R Operation of 200L (D) Operation of diversion compensation valves 35 to 40 (E) Operation and effect of hydraulic excavator (1) Front operation alone (excavation work, loading work, etc.) (A) Operation lever of flow control valves 31 to 34 Any one or more of are operated.

(B) At block 320a shown in FIG. 8, it is determined from the operation determination pattern shown in FIG. 9 that the operation is a front-only operation.
In accordance with the switching pattern shown in FIG.
00b are both turned off (open).

(C) In block 321a shown in FIG. 11, it is determined that the operation is a front-only operation similarly to block 320a, and in block 321b, the LS differential pressure Δ of main pump 200L is set according to the setting pattern shown in FIG.
ΔPc is set as both the PLSL and the LS differential pressure ΔPLSR of the main pump 200R, and the target pump tilt angle QΔP for LS control is obtained based on ΔPc in blocks 321c to 321e. This target pump tilt angle QΔP
The block 321g compares the magnitude of the target pump displacement angle QT for the input torque limiting control obtained in the block 321f with the smaller one, and the smaller one is selected as the commanded target pump displacement angle Q0. The tilt angles of the main pumps 200R and 200L are controlled so as to match the angle Q0.

(D) Blocks 74c to 74 shown in FIG.
f, the LS differential pressure Δ detected by the differential pressure detector 59c
The corresponding control forces Fc3 to Fc6 are individually calculated using Pc. The control forces Fc3 to Fc6 correspond to the delay blocks 76c to 7c.
6f, the signals are output as drive signals c to f, and the control pressures Pc3 to Pc6 corresponding to the drive signals c to f drive the shunt compensation valves 37 to 40.

(E) In the above (B), the merge separation valve 5
Since both 00a and 500b are turned off, the main pump 2
00R and 200L are both connected to the first hydraulic circuit 301, and the pressure oil discharged from the main pumps 200R and 200L joins and is supplied to the first hydraulic circuit 301. In the above (C), when the target pump tilt angle QΔP is selected in the block 321g, the main pumps 200R and 2
In 00L, LS control is performed based on ΔPc such that the pump discharge pressure becomes higher than the maximum load pressure by the target differential pressure ΔPLS0. When the target pump tilt angle QT is selected, the input torque limiting control is performed on the main pumps 200R and 200L so that the pump discharge flow rate decreases as the pump discharge pressure increases. In the above (D), the individual flow compensation valves 37 to 40 are provided with individual flow compensation characteristics, and the individual flow compensation valves 37 to 40 perform individual flow compensation control. By a combination of these operations, WO 90 / WO 90 /
As described in JP-A-13748, the actuator can be appropriately driven according to the operation characteristics of the actuator and the work machine. In addition, actuators 25 to 2
Since a sufficient flow rate of pressure oil is supplied to 8 from the two pumps, a large operation speed can be obtained. As a result, the operability of the front composite operation is improved, and efficient front work can be performed.

[0059](2) One-sided operation (pipotter)
N) (A) The operation lever of the flow control valve 29 (or 30) is operated.
Made.

(B) At block 320a shown in FIG. 8, it is determined from the operation determination pattern shown in FIG.
According to the switching pattern shown in FIG.
(Closed), and the merge separation valve 500b is turned off (open).

(C) In block 321a shown in FIG. 11, it is determined that the operation is a single operation on the traveling alone, similarly to block 320a. In block 321b, the LS differential pressure Δ of the main pump 200L is determined according to the setting pattern shown in FIG.
PLSL (or LS differential pressure ΔPLSR of main pump 200R)
Is set as ΔPa (or ΔPb). The following operations are the same as those for the front-only operation.

(D) In block 74a (or 74b) shown in FIG. 13, differential pressure detector 59a (or 59b)
The corresponding control force Fc1 (or Fc2) is calculated using the LS differential pressure ΔPa (or ΔPb) detected in b).
The control force Fc1 (or Fc2) is applied to the delay block 76a.
(Or 76b) is output as a drive signal a (or b), and the control pressure Pc1 (or Pc2) corresponding to the drive signal drives the shunt compensation valve 35 (or 36).

(E) In the above (B), the main pump 20
0L is independently connected to the third hydraulic circuit 303, the main pump 200R is independently connected to the fourth hydraulic circuit 304,
The pressure oil discharged from the main pump 200L (or 200R) is supplied to the third hydraulic circuit 303 (or the fourth hydraulic circuit 30).
4). In the above (C), the main pump 20
In the case of 0L (or 200R), the LS control is performed based on the LS differential pressure ΔPa (or ΔPb), and the input torque limiting control is performed as in the case of the front-only operation. By a combination of these operations, the traveling motor 23 (or 24)
The steering can be quickly turned at the pivot turn that drives only the steering wheel.

(3) Operation on both sides of traveling alone (straight traveling, Omagari
(Rolling, spin turn, etc.) (A) The operation levers of the flow control valves 29 and 30 are operated.

(B) In the block 320a shown in FIG. 8, it is determined from the operation determination pattern shown in FIG.
Merging separation valve 500a is turned on according to the switching pattern shown in FIG.
(Closed) and the merge separation valve 500b is turned off (open).

(C) In the block 321a shown in FIG. 11, it is determined that the operation is a single operation on both sides of travel as in the case of the block 320a, and in the block 321b, the LS differential pressure Δ of the main pump 200L according to the setting pattern shown in FIG.
ΔPa is set as PLSL, and L of the main pump 200R is set.
ΔPb is set as the S differential pressure ΔPLSR. The following operations are the same as those for the front-only operation.

(D) In block 74a shown in FIG. 13, the corresponding control force Fc1 is calculated using the LS differential pressure ΔPa detected by the differential pressure detector 59a, and in block 74b, detected by the differential pressure detector 59b. LS differential pressure ΔPb
Is used to calculate the corresponding control force Fc2. The control forces Fc1 and Fc2 are output as drive signals a and b via delay blocks 76a and 76b, and the shunt compensation valves 35 and 36 are driven by control pressures Pc1 and Pc2 corresponding to the drive signals.

(E) In the above (B), the main pump 20
0L is independently connected to the third hydraulic circuit 303, the main pump 200R is independently connected to the fourth hydraulic circuit 304,
The pressure oil discharged from the main pump 200L is supplied to a third hydraulic circuit 303, and the pressure oil discharged from the main pump 200R is supplied to a fourth hydraulic circuit 304. In the above (C), the LS control is performed on the main pumps 200L and 200R based on the LS differential pressures ΔPa and ΔPb of the associated hydraulic circuits, respectively, and the input torque limiting control is performed, similarly to the case of the front-only operation. By combining these operations, straight traveling can be performed as in the conventional case. The third and fourth hydraulic circuits 303 and 3 are used for a large-curved traveling performed by changing the speed of the left and right traveling motors 23 and 24 and a spin turn performed by reversing the driving direction of the left and right traveling motors 23 and 24.
04 is separated and the main pumps 200L, 200R are individually controlled in correspondence with the third and fourth hydraulic circuits, so that the independence of the flow rate of the pressure oil supplied to the left and right traveling motors 23, 24 is ensured. A large steering force can be obtained, and excellent steering performance can be obtained.

(4) Combined traveling operation (combined climbing traveling operation,
(A) Evacuation of mud, etc.) (A) Any one or more of the operation levers of the flow control valves 31 to 34 and the operation levers of the flow control valves 29 and / or 30 are operated.

(B) At block 320a shown in FIG. 8, it is determined from the operation determination pattern shown in FIG. 9 that it is a combined traveling operation, and at block 320b, the merge separation valve 500a is turned off according to the switching pattern shown in FIG.
(Open), and the merge separation valve 500b is turned on (closed).

(C) In block 321a shown in FIG. 11, it is determined that the combined operation is a traveling composite operation, similarly to block 320a. In block 321b, the LS differential pressure ΔPLS of the main pump 200L is set according to the setting pattern shown in FIG.
The minimum values of ΔPa and ΔPb are set as L, and ΔPc is set as the LS differential pressure ΔPLSR of the main pump 200R. The following operations are the same as those for the front-only operation.

(D) In block 74a shown in FIG. 13, the corresponding control force Fc1 is calculated using the LS differential pressure ΔPa detected by the differential pressure detector 59a, and in block 74b, detected by the differential pressure detector 59b. LS differential pressure ΔPb
Is used to calculate the corresponding control force Fc2.
c to 74f, the L detected by the differential pressure detector 59c
The corresponding control forces Fc3 to Fc6 are individually calculated using the S differential pressure ΔPc. These control forces Fc1 to Fc6 are output as drive signals a to f via delay blocks 76a to 76f, and control pressures Pc1 to Pc6 corresponding to the drive signals a to f.
Thereby, the branch flow compensating valves 35 to 40 are driven.

(E) In the above (B), the main pump 20
0L is independently connected to the second hydraulic circuit 302 (third and fourth hydraulic circuits 303 and 304), and the main pump 200R
Is independently connected to the first hydraulic circuit 301 and is connected to the main pump 2
00L is supplied to the second hydraulic circuit 302 (third and fourth hydraulic circuits 303 and 304), and the hydraulic oil discharged from the main pump 200R is supplied to the first hydraulic circuit 3
01 is supplied. In the above (C), the main pump 20
0L and 200R are the same as in the case of front-only operation,
LS differential pressure (ΔPa, ΔPb)
LS control is performed based on the minimum value and ΔPc), and the input torque limiting control is performed. In the above (D), the individual flow compensation valves 37 to 40 are provided with individual flow compensation characteristics, and the individual flow compensation valves 37 to 40 perform individual flow compensation control. By combining these operations, the first hydraulic circuit 301 and the second hydraulic circuit 302 (third and fourth hydraulic circuits 303 and 304) are separated in the combined operation of traveling and front work. Main pump 200R, 2
By controlling 00L individually in correspondence with the first and second hydraulic circuits, a sufficient amount of pressure oil can be supplied to each of the left and right traveling motors 23, 24 and the front actuators 25 to 28 by one pump. Independence of the flow rate is secured, and excellent operability is obtained.

For example, in the case of performing uphill running combined, in the conventional technique using one pump described in Japanese Patent Application Laid-Open No. 2-118203, when the pump discharge pressure P becomes high with an increase in load pressure during uphill running, Due to the input torque limiting control, the pump discharge flow rate decreases as indicated by Q0 in FIG. 14, and the front does not rise. Also, Japanese Patent Application Laid-Open No. 2-24
In the related art using two pumps described in Japanese Patent No. 8706 and the like, the pumps are divided by the left and right traveling motors. Therefore, when the pump discharge pressure P increases with an increase in the load pressure during uphill traveling, both pumps Due to the input torque limiting control, the pump discharge flow rate decreases as indicated by Q1 in FIGS. 15A and 15B, and the front does not rise as well.

On the other hand, in this embodiment, since the traveling motor and the front actuator are separated, the input torque limiting control acts on the main pump 200L for driving the traveling motors 23 and 24, and the pump discharge flow rate is reduced. FIG.
(A) decreases as indicated by Q1, but since the main pump 200R that drives the front actuators 25 to 28 is not affected by the load pressure, the discharge flow rate of the main pump 200R is indicated by Q2 in FIG. As large as possible. Therefore, a sufficient pump flow rate can be obtained in the front actuator, and the front can be raised high.

Further, when the mud is escaped, in the above-described prior art, if the load pressure of the front actuator becomes extremely higher than the load pressure of the traveling motor in order to obtain the pulling force of the arm, the pressure of the front actuator is increased. As a result, the input torque limiting control is activated, the pump discharge flow rate is reduced, the overall operation including running is slowed, and the vehicle cannot escape. In this embodiment, since the traveling motor and the front actuator are separated, the front actuators 25 to
Even if the load pressure at 28 increases, the traveling motors 23, 24
Can supply a sufficient amount of pressure oil from the main pump 200L, and the driving force of the traveling motor can be obtained, so that mud can escape.

When the front work is a work of simultaneously driving a plurality of actuators in the combined traveling operation, as described in the operation of the front only, the actuators are appropriately controlled by the individual shunt compensation control by the shunt compensation valves 37 to 40. And the composite operability is improved.

As described above, according to the present embodiment, the combined operability of the traveling and the front work such as the composite climbing and the escape of the muddy while maintaining the same steering performance as the conventional one by the traveling alone. Can be improved.

Next, some other embodiments of the present invention will be described. First, in the above embodiment, in the switching pattern of the merge separation valves 500a and 500b shown in FIG. 10, the merge separation valve 500a is turned ON when only one side of the traveling is operated.
(Closed), the junction separation valve 500b was turned off (open),
As shown in parentheses in FIG.
May be turned OFF (open), and the merge separation valve 500b may be turned ON (closed) or OFF (open). In this case, in the setting pattern of the LS differential pressure for the main pump, the minimum values of ΔPa and ΔPb are used for the main pump 200L as shown in parentheses in FIG. Also, for the main pump 200R, the merging separation valve 500b is turned on.
(Closed), use ΔPc,
When b is turned off (open), the minimum values of ΔPa and ΔPb are used.

In the illustrated embodiment in which the junction separation valve 500a is turned on (closed) and the junction separation valve 500b is turned off (open),
When the operation is switched from one side of traveling alone to both sides of traveling alone or vice versa, the merge separation valves 500a and 500b remain at the same position, so that unnecessary valve switching operation can be eliminated. Further, since the relationship between the driven hydraulic circuit and the main pump connected thereto does not change, the speed of the traveling motor does not change, and the operation can be switched smoothly. When the junction separation valve 500a is turned off (open) and the junction separation valve 500b is turned on (closed), when the operation is switched from one side of traveling alone to both sides of traveling alone or vice versa, the hydraulic circuit that is being driven is switched over. After that, since the pressure oil from one pump continues to be supplied, the speed of the traveling motor does not change, and the operation can be switched smoothly.
Turn off (open) the junction separation valve 500a, and set the junction separation valve 500
When b is set to OFF (open), the pressurized oil from the two main pumps 200L and 200R is supplied to one traveling motor, so that the spin turn can be performed quickly.

Further, in the above embodiment, the merge separation valve 50
Although a normally open on-off valve is used as 0a and 500b, a normally-closed on-off valve may be used. Also, the merging separation valve 500
Although a and 500b have been described as valves that can be switched between two positions of a "fully open position" and a "fully closed position", a valve that can be switched between two positions of a "fully open position" and a "partially open or throttle position" may be used. In the "partially open position", by setting the throttle amount appropriately, most of the pressure oil of the main pump can be supplied to the intended actuator, and substantially the same effect can be obtained. Can be In the specification of the present application, the term "connect preferentially" is used as an expression including "fully closed position" and "partially open position".

Furthermore, the merge separation valves 500a and 500b have been described as valves that can be switched between two positions, but may be flow control valves that continuously change the opening between the two positions.

In the above embodiment, the flow control valve 29 is used as a means for detecting the operation of the actuators 23 to 28.
Operation detector 29 for detecting the movement of the operation levers of Nos. 34
Although a, 30a, 31a, 32a, 33a, and 34a are used, other detectors may be used. One example is shown in FIG. In this example, a pilot operation type is used for the flow control valves 29 to 34, and the flow control valve 350 is
The spool movement direction and the stroke amount are controlled by pilot pressures Ppa and Ppb transmitted from pilot 51 via pilot conduits 352a and 352b. Operation device 351
Has an operating lever 353 and two pressure reducing valves 354a and 354b selectively operated by the operating lever 353. The pressure reducing valves 354a and 354b are connected to the pilot hydraulic pressure source 3
Based on the hydraulic pressure from 55, pilot pressures Ppa and Ppb corresponding to the operation amount of the operation lever 353 are generated. A check valve 356 is connected between the pilot lines 352a and 352b, and the pilot pressures Ppa, Ppa
The higher pressure of pb is withdrawn in line 357. Line 3
A pressure detector 358 is connected to 57, and this pressure detector 358 is used as a means for detecting operation of the actuator. The signal output from the pressure detector 358 is input to the controller 61.

Also in this embodiment, since the pilot pressure Ppa or Ppb always occurs when the actuator is operated, the operation of the actuator can be detected by the pressure detector 358.

Various other types of means for detecting the operation of the actuator can be considered. For example, a sensor for detecting the movement of the flow control valves 29 to 34 may be used. A sensor for detecting movement may be used.

In the above embodiment, the means for detecting the operation of the actuator is provided, the processing is performed electronically by the controller, and the merge separation valves 500a and 500b are controlled. You may.

[0087]

According to the present invention, the combined operability of traveling and front work is improved. For example, the front can be raised high in a combined climbing run, and in a work to escape muddy,
The force of the front actuator can be output, and mud can escape.

Further, according to the present invention, since a large steering force can be generated in the single operation of traveling, the combined operability of traveling can be improved without impairing the steering performance in the single operation of traveling.

[Brief description of the drawings]

FIG. 1 is a system diagram showing a connection relationship between a hydraulic circuit of a hydraulic construction machine and a controller according to an embodiment of the present invention.

FIG. 2 is a diagram showing details of first and second hydraulic circuits shown in FIG. 1;

FIG. 3 is a side view of the hydraulic excavator.

FIG. 4 is a top view of the excavator.

FIG. 5 is a diagram showing details of a control pressure generation circuit shown in FIG. 1;

FIG. 6 is a diagram illustrating a hardware configuration of a controller illustrated in FIG. 1;

FIG. 7 is a block diagram showing processing functions of a controller shown in FIG. 1;

8 is a block diagram showing details of a merge / separation control function among the processing functions shown in FIG. 7;

FIG. 9 is a diagram showing an operation determination pattern used in the operation determination block shown in FIG.

FIG. 10 is a diagram showing a switching pattern used in the valve switching setting block shown in FIG.

FIG. 11 is a block diagram showing details of a pump flow control function shown in FIG. 7;

12 is a diagram showing a setting pattern used in an LS differential pressure setting block shown in FIG.

FIG. 13 is a block diagram showing details of an individual branch flow compensation control function shown in FIG. 7;

FIG. 14 is a diagram showing a relationship between a pump discharge pressure and a pump discharge flow rate according to input torque limiting control in the prior art of one pump.

FIG. 15 is a diagram showing a relationship between a pump discharge pressure and a pump discharge flow rate according to input torque limiting control in the prior art of two pumps.

FIG. 16 is a diagram showing a relationship between a pump discharge pressure and a pump discharge flow rate by input torque limiting control in the embodiment shown in FIG. 1;

FIG. 17 is a view illustrating an operation detector of a hydraulic construction machine according to another embodiment of the present invention and a portion related thereto.

[Explanation of symbols]

23-28 Actuator 29-34 Flow control valve 29a-34a Operation detector 35-40 Dividing compensation valve 59a-59c Differential pressure detector 61 Controller 200R, 200L Hydraulic pump 301 First hydraulic circuit 302 Second hydraulic circuit 303 Third hydraulic circuit 304 Fourth hydraulic circuit 305 First supply line 306 Second supply line 307 Third supply line 308 (First) merging line 309 (Second) merging line 320 Merge separation control function (merge control means) 320a Operation determination block (merge control means) 320b Switching setting block (merge control means) 321 Pump flow rate control function (first and second pump control means) 322 Individual divert compensation control function 500a (First) merging separation valve (valve means) 500b (second) merging separation valve (valve means)

Continuation of the front page (56) References JP-A-2-279839 (JP, A) JP-A-2-261132 (JP, A) JP-A-1-316502 (JP, A) JP-A-4-194405 (JP) , A) JP-A-3-84202 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02F 9/22 F15B 11/00 F15B 11/05 F15B 11/17

Claims (7)

(57) [Claims] At least two hydraulic pumps and two hydraulic pumps
A plurality of hydraulic actuators driven by the hydraulic oil discharged from the two hydraulic pumps, a flow control valve for controlling a flow of the hydraulic oil supplied to each of the plurality of hydraulic actuators, and a discharge of each of the two hydraulic pumps First pump control means for controlling the flow rate so that the pump discharge pressure is higher than the maximum load pressure of the hydraulic actuator driven by each hydraulic pump, and the pump discharge flow rate decreases as the pump discharge pressure increases Second pump control means for controlling the discharge flow rate of each of the two hydraulic pumps, wherein the plurality of actuators are at least one front actuator and at least one front actuator.
(A) a first hydraulic circuit including the front actuator and its flow control valve, and a second hydraulic circuit including the travel actuator and its flow control valve; A first position installed between the two hydraulic pumps and the first and second hydraulic circuits and connecting the two hydraulic pumps to at least the first hydraulic circuit; Valve means having a second position, one of which is connected preferentially to the first hydraulic circuit and the other is preferentially connected to the second hydraulic circuit; and (c) only the front actuator is operated. Moving the valve means to the first position, and moving the valve means to the second position when the front actuator and the travel actuator are simultaneously operated. Hydraulic construction machine characterized in that it comprises: a merging control means having a function to move. 2. The hydraulic construction machine according to claim 1, wherein one of said two hydraulic pumps is connected to said first hydraulic circuit via a first supply line, and the other is a second supply line. And the first and second supply lines are connected to each other through a merging line, and the valve means is connected to the merging and separating line disposed in the merging line. A hydraulic construction machine comprising a valve. 3. The hydraulic construction machine according to claim 1, wherein the travel actuator includes left and right travel actuators, and the second hydraulic circuit includes a third hydraulic circuit including the right travel actuator and a flow control valve thereof. A fourth hydraulic circuit including the left traveling actuator and a flow control valve thereof, wherein the valve means connects one of the two hydraulic pumps to the third hydraulic circuit preferentially and the other to the third hydraulic circuit. A third position preferentially connected to the hydraulic circuit of No. 4;
The hydraulic construction machine according to claim 1, wherein the merging control means moves the valve means to the third position when only the traveling actuator is operated. 4. The hydraulic construction machine according to claim 3, wherein one of the two hydraulic pumps is connected to the first hydraulic circuit via a first supply line, and the other is a second supply line. And the fourth hydraulic circuit is connected to the third hydraulic circuit via the third hydraulic circuit to supply pressure oil to the fourth hydraulic circuit.
And the third supply line is connected to the first supply line via a first junction line, and the second supply line is connected to the second supply line.
And the valve means are disposed on the first merging separation valve disposed on the first merging conduit and on the second merging conduit. A hydraulic construction machine, comprising: a second merge separation valve. 5. The hydraulic construction machine according to claim 1, wherein first differential pressure detecting means for detecting a differential pressure between a supply pressure of the first hydraulic circuit and a load pressure of the front actuator, and the second differential pressure detecting means. A second differential pressure detecting means for detecting a differential pressure between a supply pressure of the hydraulic circuit and a load pressure of the travel actuator, wherein the first pump control means is configured such that the valve means has the first position. When moved to the first
Controlling the discharge flow rates of the two hydraulic pumps based on the differential pressure detected by the differential pressure detecting means, and when the valve means is moved to the second position, the first differential pressure detecting means Controlling the discharge flow rate of one of the two hydraulic pumps based on the differential pressure detected in step (a), and controlling the other discharge flow rate based on the differential pressure detected by the second differential pressure detection means. Hydraulic construction machinery. 6. A hydraulic construction machine according to claim 3 , wherein said first differential pressure detecting means detects a differential pressure between a supply pressure of said first hydraulic circuit and a load pressure of said front actuator; Second pressure difference detecting means for detecting a pressure difference between the supply pressure of the hydraulic circuit and the load pressure of the right travel actuator, and a difference between the supply pressure of the fourth hydraulic circuit and the load pressure of the left travel actuator. And a third differential pressure detecting means for detecting a pressure, wherein the first pump control means comprises: when the valve means is moved to the first position,
The discharge flow rates of the two hydraulic pumps are respectively controlled based on the differential pressure detected by the first differential pressure detection means, and when the valve means is moved to the second position, the first flow rate is set to the first position.
The discharge flow rate of one of the two hydraulic pumps based on the differential pressure detected by the differential pressure detecting means, and the other based on the smaller of the differential pressures detected by the second and third differential pressure detecting means. When the valve means is moved to the third position, the discharge flow rate of one of the two hydraulic pumps is controlled based on the differential pressure detected by the second differential pressure detecting means. A hydraulic construction machine, wherein the other discharge flow rate is controlled based on the differential pressure detected by the third differential pressure detecting means. 7. The hydraulic construction machine according to claim 1, further comprising operation detecting means for detecting respective operations of said front actuator and said traveling actuator, wherein said merging control means receives a signal from said operation detecting means. A hydraulic construction machine, wherein it is determined whether or not the front actuator and the traveling actuator have been operated at the same time.