JP2765605B2 - Hydraulic working machine hydraulic circuit - 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 circuit and a valve structure of a hydraulic working machine such as a hydraulic shovel, and more particularly, to simultaneously operating a plurality of actuators provided in a hydraulic working machine, the magnitude of the load of each actuator. TECHNICAL FIELD The present invention relates to a hydraulic circuit and a valve structure of a hydraulic working machine capable of reliably performing a combined operation regardless of the hydraulic circuit.

[0002]

2. Description of the Related Art The prior art of a hydraulic circuit relating to a combined operation of a hydraulic working machine of this kind is disclosed in Japanese Patent Publication No. 62-25827. A conventional technique substantially equivalent to this known example will be described with reference to FIG.

FIG. 5 shows a hydraulic circuit for driving an arm cylinder 40 for driving an arm forming a front member of a hydraulic shovel and a swing motor 50 for rotating a swing body. As shown in FIG. 5, the hydraulic circuit according to the prior art includes a direction switching valve 21 for guiding the hydraulic oil supplied from the hydraulic source 2 to the turning motor 50 and a direction switching valve 23 for guiding the oil to the arm cylinder 40. And The directional control valves 21 and 23 are provided with center bypass passages 110 and 120 for communicating the center bypass pipes b and r with the tank 100 at the time of neutral, and check valves provided on pipes branched from the center bypass pipes b and r. 111, 123, first input ports 51a, 51b for taking in hydraulic oil via F,
Second input ports 52a, 52b, tank ports 54a, 54b leading to the tank 100, and output ports 55a, 55 leading to the swing motor 50 and the arm cylinder 40.
b, 57a and 57b. On the other hand, the pipeline 121 connected to the first input port 51b of the direction switching valve 23 installed on the downstream side with respect to the hydraulic pressure source 2 and the second input port 5
A fixed throttle G0 is provided on a pipe 151 connecting the branch pipe 122 connected to 2b.

In the hydraulic circuit according to the prior art configured as described above, when the directional control valve 21 is operated to supply pressure oil to the swing motor 50, the center bypass input port 53a of the directional control valve 21 is blocked. The pressure oil is supplied from the first input port 51a or the second input port 52a through the check valve 111 to the output port 55a or
It is guided to 57a and is supplied to the turning motor 50 by the pipe m or n. The hydraulic oil discharged from the turning motor 50 is supplied to the tank 10 via the tank port 54a.
Returned to 0.

In this state, when the directional control valve 23 is operated to the side 23a, the pressure oil which has flowed out to the branch pipe z is returned to the check valve 12a.
3. The fluid reaches the second input port 52b via the fixed throttle G0, is guided to the pipeline f by the passage 124a and the output port 57b, and is supplied to the oil chamber on the bottom side of the arm cylinder 40. The hydraulic oil discharged from the oil chamber on the rod side of the arm cylinder 40 is supplied to the direction switching valve 23 via the pipe s.
Is returned to the tank 100 by the tank port 54b.

Generally, in a hydraulic excavator, the weight of the arm acts in the direction of pushing the rod, and therefore, when an operation of supplying pressure oil to the bottom side of the arm cylinder 40 (hereinafter referred to as an arm cloud) is performed, The bottom pressure of the cylinder 40 decreases. On the other hand, the swing motor 5
0 for the pressure becomes high at the time of startup, when connected to a simple parallel to the direction switching valve 21 and the directional control valve 23, thus most of the pressurized oil flows through the light arm cylinder 40 side load . On the other hand, by providing the fixed throttle G0 as described above, even if the load on the arm is small, the branch pipe z
Is maintained at a pressure required for the rotation motor 50 to rotate.

Conversely, when the directional control valve 23 is operated to the side 23b, the center bypass input port 53b and the second
Is blocked, the branch line z
The pressure oil that has flowed out through the check valve 123 is guided to the first input port 51b through the check valve 123, and the passage 124b, the output port 55b,
The oil is supplied to the oil chamber on the rod side of the arm cylinder 40 via the pipe s. On the other hand, the hydraulic oil discharged from the oil chamber on the bottom side of the arm cylinder 40 is supplied to the pipeline f, the output port 57b,
It is returned to the tank 100 via the tank port 54b. As described above, when supplying the pressure oil to the oil chamber on the rod side of the arm cylinder 40, the pressure oil does not pass through the fixed throttle G0, so that the circuit pressure loss is small.

In the case of the arm alone operation, the pressure oil from the pipe r and the branch pipe z is supplied to the check valve 123, regardless of whether the directional control valve 23 is operated to any one of 23a and 23b.
The signal is supplied to the first input port 51b or the second input port 52b via F and the fixed aperture G0. At this time, since the pressure in the branch pipe z and the pressure in the center bypass pipe r are substantially equal, the flow rate passing through the fixed throttle G0 is small, and the pressure loss in the fixed throttle G0 is small.

Therefore, in the above-described hydraulic circuit according to the prior art, when the revolving structure and the arm are combinedly operated, in the case of the arm cloud, the pressure in the branch conduit z is maintained at a high pressure by the fixed throttle G0. The pressure oil can be supplied to the turning motor 50. Otherwise,
Since the amount of hydraulic oil flowing through the fixed throttle G0 is small, pressure loss due to the fixed throttle G0 can be reduced.

[0010]

However, in the above-described hydraulic circuit according to the prior art, since the flow characteristics of the fixed throttle G0 are fixed, there are the following problems. That is, for example, in order to expand the working range of the excavator, when the excavator is replaced with a longer arm in place of the arm provided as a standard in the excavator, the load applied to the arm cylinder 40 increases, and the arm cloud increases. The supply pressure of the pipe f during operation decreases. For this reason, in the flow characteristic of the fixed throttle G0 set according to the arm provided as a standard, in the combined operation of the swing motor 50 and the arm cylinder 40, when the arm cloud operation is performed, most of the pressure oil is removed. It flows to the arm cylinder 40 side, and the predetermined turning force of the revolving body cannot be obtained.

In order to improve the turning force, when a fixed aperture G0 having a small opening area is used,
The arm speed at the time of the combined operation decreases, and the work efficiency deteriorates.

From these facts, in the case of the fixed stop G0 as in the above-mentioned prior art, the turning operation and the arm combined operation are
Optimal flow characteristics in accordance with the operation amounts of the respective directional control valves could not be set.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to provide a hydraulic work system capable of applying a predetermined driving force to an actuator even when the load applied to the actuator changes. To provide a hydraulic circuit for the machine.

[0014]

In order to achieve the above object, the present invention provides a hydraulic power source, a plurality of actuators driven by hydraulic oil supplied from the hydraulic source, and a flow of hydraulic oil to these actuators. A plurality of directional control valves, and a first directional control valve of which the positional relationship among the plurality of directional control valves is upstream with respect to the hydraulic pressure source and a second direction which is downstream with respect to the hydraulic pressure source At least two directional switching valves of the switching valve, when in a neutral position, branch off from a center bypass passage communicating between a center bypass line connected to the hydraulic pressure source and the tank, and the center bypass line near the hydraulic pressure source. A first input port connected to the first branch pipe, a second input port connected to a second branch pipe branched from the center bypass pipe, and a tank port connected to the tank. , And an output port connected to the serial actuator, a shape of the first directional control valve, those
Before the operation amount of the first directional control valve reaches the maximum value,
Closing the center bypass passage of the first directional control valve;
A check valve set in a shape having a closed position and provided on the second branch line of the second directional switching valve so as to allow only the inflow from the center bypass line; A hydraulic working machine that is branched from between a valve and the second input port, and that includes a flow control unit provided on a pipe connecting the first branch pipe and the second branch pipe; in the hydraulic circuit, the flow control means, as well as operate according to the operation amount of the first directional control valve, the first direction
It continues to operate until the operation amount of the directional control valve reaches the maximum value, characterized in that example Bei adjusting means for adjusting the flow characteristics.

[0015]

Since the hydraulic circuit of the hydraulic working machine according to the present invention is constructed as described above, the first and second directional control valves provided upstream and downstream with respect to the hydraulic pressure source are both in the neutral position. In this case, the pressure oil supplied from the hydraulic pressure source is guided to the tank via the center bypass passage of the direction switching valve.

Also, a first hydraulic pressure source provided upstream of the hydraulic pressure source is provided.
Is the neutral position and the second directional control valve is provided on the downstream side.
Is operated, the first directional switching valve is connected to the second directional switching valve by the first branch pipe branched from the vicinity of the hydraulic power source.
The pressure oil is led to the input port of the first port, and the pressure oil is led to the second input port via the check valve by the second branch line branched from the center bypass line. At this time, a flow control means is provided on a pipe connecting the first branch pipe and the second branch pipe, and a first input port,
Most of the pressure oil is supplied to one of the input ports according to the connection state between the second input port and the output port.

When only the first directional control valve is operated, the opening area of the center bypass passage is reduced in accordance with the amount of operation of the first directional control valve, and the second bypass passage is connected to the second bypass switch. The amount of pressure oil flowing into the directional control valve decreases. Further, the operation amount of the first directional control valve increases,
When the center bypass passage is closed, the supply of the pressure oil to the second directional control valve is shut off.

When the first directional control valve and the second directional control valve are both operated, the opening area of the center bypass passage of the first directional control valve is changed to the first directional control valve. , The amount of pressure oil supplied from the center bypass line to the second directional control valve is reduced, but the pressure oil from the first branch line is supplied to the first input port. , And a second input port.

At this time, when the first input port and the output port are in communication, a flow rate according to the state of the load applied to the actuator is supplied to the first input port.
On the other hand, the adjusting means provided in the flow control means operates according to the operation amount of the first directional control valve, and the flow rate between the first branch pipe line and the second branch pipe line is controlled. Along with the decrease in the opening area of the center bypass passage of the directional control valve 1, the flow of the pressure oil from the center bypass line becomes very small. Conversely, when the second input port and the output port are in communication with each other, the pressure oil supplied to the second input port is supplied via the flow rate control means, and is thus connected to the second direction switching valve. Actuator load conditions, and
The amount of oil controlled by the flow characteristics of the flow control means, which is adjusted according to the amount of operation of the first direction switching valve, is supplied to the actuator.

Therefore, according to the hydraulic circuit of the present invention,
Even if the state of the load applied to the actuator changes, a predetermined amount of pressure oil can be supplied to each actuator, particularly during the combined operation, and a driving force corresponding to this can be given.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 are explanatory views of a first embodiment according to claims 1 and 3 of the present invention. FIG. 1 is a hydraulic circuit diagram according to the first embodiment, and FIG. 2 is a first direction switching. FIG. 9 is a diagram showing a relationship between the operation amount of a turning direction switching valve corresponding to a valve, the opening area of a center bypass passage of the turning direction switching valve, and the opening area of a variable throttle corresponding to a flow rate control means. is there.
Note that portions common to the hydraulic circuit according to the related art shown in FIG. 5 are denoted by the same reference numerals.

As shown in FIG. 1, the hydraulic circuit according to the first embodiment includes a direction switching valve 21 for guiding hydraulic oil supplied from a hydraulic source 2 to a swing motor 50 and an arm cylinder 40. And a direction switching valve 23 for guiding. In addition,
The direction switching valve 21 is installed on the upstream side with respect to the hydraulic pressure source 2, and the direction switching valve 23 is installed on the downstream side with respect to the hydraulic pressure source 2.
1 corresponds to a first direction switching valve, and the direction switching valve 23 corresponds to a second direction switching valve. The directional control valves 21 and 23 are provided with center bypass passages 110 and 120 for communicating the center bypass pipes b and r with the tank 100 at the time of neutral, and check valves provided on pipes branched from the center bypass pipes b and r. 11
A first input port 51a, 51b, a second input port 52a, 52b for taking pressure oil through 1, 123, F;
Tank ports 54a and 54b leading to the tank 100 and output ports 55a, 55b, 57a and 57b leading to the turning motor 50 and the arm cylinder 40 are provided.
On the other hand, a pipe 151 connecting a pipe 121 connected to the first input port 51b of the directional control valve 23 and a branch pipe 122 connected to the second input port 52b is provided as a flow control means. A variable aperture 300 is provided. The pipe z branched from the center bypass pipe b corresponds to a first branch pipe, and the pipe 122 branched from the center bypass pipe r corresponds to a second branch pipe.

The directional control valve 21 has a pilot pump 301,
A pilot pressure set by the relief valve 302 is supplied, and the position is switched by the pilot pressure. further,
The pilot valve 303 includes pressure reducing valves 303A and 303B for adjusting the pilot pressure according to the operation amount of the operation lever. Among the pilot pressures guided by the pressure reducing valves 303A and 303B, the pilot pressure on the high pressure side is selected by the shuttle valve 304, and is guided to the variable throttle 300 via the pipeline 305.

The pressure reducing valves 303A and 303B
The pilot pressure guided by the pilot valve 3
03, which is proportional to the operation amount of the operation lever forming the center bypass passage 1 along with the movement of the direction switching valve 21.
There is also a close relationship between the aperture area of the aperture stop 10 and the aperture area of the variable stop 300. As shown in FIG. 2, the shape of the directional control valve 21 of the first embodiment is such that the opening area of the center bypass passage 110 is sharply reduced when the operation lever is slightly operated from the neutral position, and Accordingly, the center bypass passage 110 is set to be gradually decreased in proportion to the operation amount, and to close the center bypass passage 110 at the position C before the maximum operation amount of the operation lever. Such a setting can be realized, for example, by considering the shapes of the spool and the land. Further, when the operation amount of the operation lever is C
When it becomes larger, the spring is adjusted so that the variable throttle 300 starts to move to the right with respect to FIG. 1 by the pilot pressure, and the opening area thereof gradually decreases.

In the hydraulic circuit according to the first embodiment configured as described above, the direction switching valve 21 and the direction switching valve 23
Are set to the neutral position, the center bypass line b
Is the tank 1 by the center bypass passages 110 and 120.
The pressure oil discharged from the hydraulic pressure source 2 is returned to the tank 100 to communicate with the hydraulic pressure source 00.

When the operating lever of the pilot valve 303 is operated to supply pressure oil to the swing motor 50, the direction switching valve 21 is moved by the pilot pressure supplied from the pressure reducing valve 303A and the pressure reducing valve 303B.
The opening area of the center bypass passage 110 is reduced. For this reason, the center bypass passage 110 becomes a throttle, and the outflow rate to the center bypass pipe r decreases. On the other hand, most of the pressure oil is supplied to the first input port 51 through the check valve 111.
a or the output port 5 from the second input port 52a
It is guided to 5a or 57a and is supplied to the turning motor 50 by a pipe m or n. The hydraulic oil discharged from the turning motor 50 is returned to the tank 100 via the tank port 54a.

In this state, when the direction switching valve 23 is operated to the side 23a, that is, when the arm cloud operation is performed,
Since the first input port 51b is blocked, the pressure oil flowing out to the center bypass line r is guided to the branch line 122 via the check valve F, and the pressure oil flowing out to the branch line z is checked. Branch line 12 via valve 123 and variable throttle 300
2 and merges with the pressure oil from the branch line z and is guided to the second input port 52b. This second input port 52b
The pressure oil led to the passage 124a and the output port 57
The oil is guided to the conduit f by b and supplied to the oil chamber on the bottom side of the arm cylinder 40. The hydraulic oil discharged from the oil chamber on the rod side of the arm cylinder 40 is supplied to the tank 1 by the tank port 54b of the direction switching valve 23 via the pipe s.
Returned to 00. At this time, as shown in FIG. 2, according to the operation amount of the operation lever of the turning pilot valve 303,
Since the opening area of the center bypass passage of the directional control valve 21 and the opening area of the variable throttle 300 are reduced, the outflow flow rate to the center bypass line r is reduced, and the pressure in the branch line z is also high. , The flow rate passing through the variable throttle 300 also decreases, and the amount of pressure oil supplied to the arm cylinder 40 decreases. That is, when the operator of the working machine increases the operation amount of the turning operation lever in order to increase the turning speed, the supply amount of the pressure oil to the arm cylinder 40 decreases, while the operating speed of the arm increases. When the operation amount of the turning operation lever is reduced in order to give priority to the above, the opening area of the center bypass passage of the direction switching valve 21 and the opening area of the variable throttle 300 become relatively large, and the arm cylinder 40 side Will be supplied with a large amount of pressure oil.

On the other hand, when the directional control valve 23 is operated to the side 23b, the second input port 52b is blocked, and
21 and the conduit s communicate with each other through the passage 124b,
The pressure oil from the branch pipe z is guided to the rod-side oil chamber of the arm cylinder 40 via the first input port 51b.
At this time, since the pressure on the rod side of the arm cylinder 40 is high, the pressure oil is also supplied to the swing motor 50 side without performing flow rate control. Therefore, the center bypass passage 1 of the direction switching valve 21 is operated by operating the turning operation lever.
Even if the opening area of 10 is reduced, a predetermined amount of pressure oil is supplied to the arm cylinder 40 and the swing motor 50.

In the case of the arm alone operation, regardless of whether the directional control valve 23 is operated to any one of 23a and 23b, the pressure oil from the pipe r and the branch pipe z receives the check valve 123,
F and the variable aperture 300 are supplied to the first input port 51b or the second input port 52b. At this time, since the pressure in the branch pipe z and the pressure in the center bypass pipe r are almost equal, the flow rate passing through the variable throttle 300 is small, and the pressure loss in the variable throttle 300 is small.

Accordingly, in the hydraulic circuit according to the first embodiment, the opening area of the variable throttle 300 and the center bypass passage of the directional control valve 21 is limited by the operation of the turning operation lever by the operator operating the working machine. Since the control is performed in accordance with the amount, even if the condition of the load applied to the arm cylinder 40 changes, a predetermined amount of pressure oil can be supplied to the rotation motor 50, thereby providing a predetermined rotation force. .

FIGS. 3 and 4 show claims 1, 2 and 3 of the present invention.
FIG. 3 is a configuration diagram of the second embodiment, and FIG. 4 is a diagram illustrating the operation amount of a turning operation lever and a variable throttle 300 provided in the second embodiment. FIG. 6 is a diagram showing a relationship between the turning direction switching valve and an opening area of a center bypass passage. 1 and 2 which are explanatory diagrams of the first embodiment are denoted by the same reference numerals, and description thereof will be omitted.

In the second embodiment, a variable throttle 300 provided on a pipe 151 connected to a branch pipe z, an electromagnetic proportional valve 520 as driving means for supplying pilot pressure to the variable throttle 300, and Detector 6 for detecting the pilot pressure on the high pressure side guided by shuttle valve 304
00. Further, an input switch 500 for specifying whether to give priority to the arm operation or the turning operation at the time of the composite operation, a signal from the input switch 500, and a detection signal from the pressure detector 600 are input, A calculation means 510 is provided for calculating a supply pressure to the variable throttle 300 based on the input signal and outputting a drive signal corresponding to the calculation result to the electromagnetic proportional valve 520.

The calculating means 510 receives the signal from the input switch 500 and the detection signal from the pressure detector 600. The input section 510a receives the signal from the pressure detector 600. Of the turning operation lever and the variable aperture 30 corresponding to the signal of
Data portion 510c for presetting the relationship with the opening area of 0
A calculation unit 510b that receives a signal from the input unit 510a, reads data stored in the data unit 510c, and calculates an output signal to the electromagnetic proportional valve 520;
The signal from the arithmetic unit 510b is input to the electromagnetic proportional valve 52
The output unit 510d converts the drive signal to 0 and outputs the drive signal.

As described in the first embodiment, when the arm cloud is performed at the time of the turning operation, if the turning operation is given priority, the pressure in the branch pipe z is changed so as to maintain a high value. While reducing the aperture area of the diaphragm 300,
It is only necessary to reduce the opening area of the center bypass passage of the directional control valve for turning, and conversely, if priority is given to the arm operation, the opening area of the variable throttle 300 and the center bypass passage of the directional switching valve for turning is reduced. What is necessary is just to make it larger. For this reason, in the second embodiment, data corresponding to the case where the turning operation is prioritized and two types of data corresponding to the case where the arm operation is prioritized are previously stored in the data unit 510c.
To be stored. That is, as shown in FIG. 4, the relationship between the operation amount of the turning operation lever corresponding to the pressure signal detected by the pressure detector 600 and the opening area of the variable throttle 300 is determined by giving priority to arm operation, or The opening area can be selected according to whether the turning operation has priority. When the signal from the input switch 500 indicates that the arm operation is to be prioritized, the opening area of the variable aperture 300 is set to relatively gradually decrease with respect to the operation amount of the operation lever, whereas the turning operation is performed. When priority is given to, it is set to decrease relatively steeply.

As in the first embodiment, the opening area of the center bypass passage of the directional control valve for turning rapidly decreases in the vicinity of the neutral position to reach the position C before the maximum operation amount is reached. To be closed.

Since the second embodiment is constructed as described above, the operation section 510b operates the turning operation lever stored in the data section 510c in accordance with the signal designated by the input switch 500. Variable aperture 30 for
The data regarding the opening area of 0 is selected. For example, when the turning operation priority is instructed by the input switch 500, the data stored in the data section 510c and whose opening area decreases sharply is selected and read. Then, based on the pressure signal from the pressure detector 600, the opening area of the variable throttle 300 is obtained, and the supply pressure to the variable throttle 300 for obtaining the opening area is calculated and output.

The output unit 510d receives a signal from the arithmetic unit 510b and calculates and outputs a drive signal to the electromagnetic proportional valve 520 according to the input signal. For example, the arithmetic unit 5
When the opening area of the variable aperture 300 is made smaller than 10b, that is, when it is instructed to apply a high pressure (turning operation has priority), a high-current drive signal is output to the drive coil of the electromagnetic proportional valve 520. Conversely, the operation unit 510b
When it is instructed to apply a lower pressure (arm operation priority), a low-current drive signal is output.

When the drive signal from the calculating means 510 is input, the electromagnetic proportional valve 520 supplies and shuts off the pressure oil to the variable throttle 300 in accordance with the input signal, and the variable throttle 300
Control the opening area of

Therefore, according to the second embodiment,
When the input switch 500 gives an instruction as to which of the arm operation and the turning operation is to be prioritized, the pressure in the branch pipe z is increased by the instruction signal from the input switch 500, the pressure detector 600, and the turning operation lever. Since the pressure is set according to the operation amount, the driving force of each actuator at the time of the combined operation can be varied according to the work content, as in the first embodiment described above.

In the first and second embodiments described above, only the combined operation of the arm and the turning has been described.
When the three operations of the boom lowering operation in addition to the arm cloud are performed in combination, the supply of pressure oil to the swing motor also decreases,
Turning acceleration deteriorates. Therefore, to detect the operation of the boom, for example, to detect the pilot pressure of the boom directional control valve, the relationship between the opening area of the variable throttle with respect to the operation amount of the boom operation lever, the data unit in the arithmetic unit Remember
Based on this, the supply pressure to the variable throttle may be controlled.

Although a variable throttle has been described as the flow control means, a flow control valve having a pressure compensation function or a variable relief valve may be used instead of the variable throttle.

[0043]

As described above, according to the present invention, the amount of pressurized oil supplied to each actuator can be easily adjusted in accordance with the load applied to the actuator. However, a predetermined driving force can be applied to each actuator during the combined operation, the operation of the actuator as intended by the operator can be realized, and the working efficiency can be improved as compared with the conventional case. Also provided in the flow control means,
The adjusting means for adjusting the operability is such that the operation amount of the first directional control valve is
Since it continues to operate up to the maximum value,
Next, the center bypass passage of the first directional control valve is closed.
From the closed position to the end position corresponding to the maximum value of the operation amount
Exists as a non-control area in consideration of manufacturing errors
In other words, it was considered dead space until then.
What has not been used, the present invention uses a flow control means.
Effectively used as a control area to control the characteristics of the passing flow rate
Can be used, and from this point of view,
The metering characteristics of the directional control valve can be improved.
You. In particular, in the invention according to claim 2, the flow rate control means
The above-described adjusting means provided for the first directional control valve operates the first directional control valve.
Work volume corresponds to the closed position of the center bypass passage
It keeps operating until it reaches the maximum value from the amount of operation
Because it regulates the flow rate, the first directional control valve
Of closing the center bypass passage of the
Flow control independent of flow characteristics through directional control valve
The flow characteristics in the means can be adjusted and accordingly
If you want to change the flow characteristics in this flow control
Change the flow characteristics of the first directional control valve.
Changes can be performed independently and
The work of changing the flow characteristics in the quantity control means is simple.

In particular, according to the third and fourth aspects of the present invention, the priority order of the operation speeds of the actuators in the combined operation can be instructed, and each actuator operates at the speed according to the instruction. The driving force of each actuator can be varied according to the work content.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic working machine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between an operation amount of a turning operation lever, a variable throttle, and an opening area of a turning direction switching valve according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a main part of a second embodiment of the present invention.

FIG. 4 is a diagram showing a relationship between an operation amount of a turning operation lever, a variable throttle, and an opening area of a turning direction switching valve in a second embodiment of the present invention.

FIG. 5 is a hydraulic circuit diagram of a conventional hydraulic working machine.

[Explanation of symbols]

 2 Hydraulic source 21 Direction switching valve (first direction switching valve) 23 Direction switching valve (second direction switching valve) 40 Arm cylinder (actuator) 50 Swing motor (actuator) 51a, 51b First input port 52a, 52b Second input port 54a, 54b Tank port 55a, 55b, 57a, 57b Output port 100 Tank 110, 120 Center bypass passage 122 Branch line (second branch line) 123 Check valve (first check valve) ) 151 Pipeline 300 Variable throttle (flow control means) 301 Pilot pump 303 Pilot valve 304 Shuttle valve 305 Pilot pipe 500 Input switch (Input means) 510 Calculation means 520 Electromagnetic proportional valve (Drive means) 600 Pressure detector (Detection means) B, r Center bypass line F Check valve (second Check valve) z Branch line (first branch line)

Claims (6)

(57) [Claims] A hydraulic pressure source, a plurality of actuators driven by hydraulic oil supplied from the hydraulic pressure source, and a plurality of directional control valves for controlling a flow of hydraulic oil to the actuators; When at least two of the first directional control valve and the second directional control valve of which the positional relationship is upstream with respect to the hydraulic pressure source are the neutral position, A center bypass passage connecting the center bypass line connected to the hydraulic pressure source to the tank, and a first input port connected to a first branch line branched from the center bypass line near the hydraulic pressure source; A second input port connected to a second branch pipe branched from the center bypass pipe, a tank port connected to a tank, and an output port connected to the actuator. The shape of the first directional control valve, the first directional control
This first direction switching is performed before the operation amount of the switching valve reaches the maximum value.
The valve has a closed position for closing the center bypass passage.
Set that shape, the said second branch pipe path of the second directional control valve, a check valve disposed to allow only inflow from the center bypass line, and the check valve In a hydraulic circuit of a hydraulic working machine, the hydraulic circuit is branched from between a second input port and provided with flow control means provided on a pipeline connecting the first branch pipeline and the second branch pipeline. , the flow rate control means, as well as operate according to the operation amount of the first directional control valve, the operation of the first directional control valve
It continues to operate until the amount reaches the maximum value, the hydraulic circuit of a hydraulic working machine, characterized in that example Bei adjusting means for adjusting the flow characteristics. 2. The directional control valve according to claim 1, wherein the adjusting means is a first directional control valve.
Is operated by the center bypass of the first directional control valve.
Movement after reaching the operation amount corresponding to the closed position of the
Operation, and continues to operate until the maximum value is reached.
2. The method according to claim 1, wherein the quantity characteristic is adjusted.
The hydraulic circuit of the hydraulic working machine according to 1. 3. An input means for setting a flow characteristic of the flow control means, and an operating force for operating the adjusting means is calculated based on the flow characteristic set by the input means, and a signal corresponding to the calculation result is output. calculating means for outputting, to the input signal from the operation means, hydraulic described a drive signal corresponding to the signal to claim 1 or 2, characterized in that a drive means for outputting to said adjusting means Hydraulic circuit of work machine. 4. A hydraulic circuit of a hydraulic working machine according to any one of claims 1-3, characterized in that said flow control means is a variable throttle. Wherein said flow control means is characterized in that it is a flow control valve having a pressure compensating function according to claim 1-3 Neu
The hydraulic circuit of the hydraulic working machine described in any of the above. Wherein said flow control means is a hydraulic circuit of a hydraulic working machine according to any one of claims 1-3, characterized in that the variable relief valve.