JPH07173859A - Hydraulic drive device of hydraulic working equipment - Google Patents

Abstract

PURPOSE:To embody a required multiple performance without forced throttling performance accompanied by the operation of a high load pressure actuator of a pressure compensation valve which is related with a low load pressure actuator. CONSTITUTION:A first changeover valve 7 and a second changeover valve 8, both of which serve as a directional changeover valve, are connected to a boom cylinder 9 which is a specific actuator in parallel. A hydraulic pump 1 is connected to the directional changeover valve 7 while a hydraulic pump 8 is connected to the directional changeover valve 8. A first output means 26a of a controller 26 holds the neutrality of the directional changeover valve 7 or the directional changeover valve 8 during multiple driving with a bucket cylinder 19 or an arm cylinder 20 and regulates the supply of pressure oil to the boom cylinder 9 from the directional changeover valve 7 or 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic drive system for a hydraulic working machine such as a hydraulic excavator having a plurality of actuators. And a pressure compensating valve that controls a differential pressure between the upstream side and the downstream side, which is a differential pressure between the upstream side and the downstream side.

[0002]

2. Description of the Related Art As a conventional technique of this type, for example, there is one disclosed in Japanese Patent Laid-Open No. 240403/1990. In this conventional technique, a plurality of actuators such as a boom cylinder and an arm cylinder can be combinedly driven by pressure oil discharged from one variable displacement hydraulic pump. Between the hydraulic pump and the actuator, a flow control valve,
A direction switching valve is provided upstream of the flow rate control valve, and has a diversion compensation valve that controls a differential pressure across the flow rate control valve, which is a differential pressure between the upstream pressure and the downstream pressure, that is, a pressure compensation valve. ing. In this prior art, with the control of the differential pressure across the flow control valve by the respective pressure compensation valves,
An actuator, for example, an arm cylinder related to the corresponding pressure compensating valve and the flow control valve can be driven by controlling the opening amount of the corresponding flow control valve without being influenced by the fluctuation of the load pressure of another actuator, for example, the boom cylinder. That is, a composite drive of a plurality of actuators that can cause a difference in load pressure between each other, such as drive of an arm cylinder and drive of a boom cylinder, is performed according to the opening amount of each flow control valve related to this composite drive. This is realized by appropriately dividing the pressure oil of one hydraulic pump.

[0003]

In the above-mentioned prior art, when a low load pressure actuator is being driven, the corresponding directional control valve is operated in an attempt to simultaneously drive the high load pressure actuator. In case,
In a saturation state where the sum of the required flow rate of each actuator is larger than the flow rate that can be discharged from the hydraulic pump, in order to prevent pressure oil from flowing only to the low load pressure actuator, The pressure compensating valve included in the directional control valve that controls the actuator is operated so that the opening amount of the pressure compensating valve is smaller than before, and the pressure oil of the pump is also distributed to the directional control valve related to the high load pressure actuator. It is possible to realize combined drive of an actuator having a low load pressure and an actuator having a high load pressure, which are supplied by flowing.

Therefore, in this prior art, in the above-mentioned saturation state when the high load pressure actuator is simultaneously driven in combination while the low load pressure actuator is being driven as described above, the low load pressure actuator is supplied to the low load pressure actuator. As a result, the flow rate decreases, and the operating speed of the low load pressure actuator decreases.
Such a decrease in the operating speed tends to cause a situation in which the work efficiency is reduced to a degree that cannot be ignored depending on the type of work performed through the operation of the actuator with a low load pressure.

At this time, as described above, the pressure compensation valve relating to the actuator having a low load pressure is throttled, so that heat loss occurs in the pressure compensation valve, that is, energy loss in which energy is wasted is generated. Cheap.

The present invention has been made in view of the above-mentioned circumstances in the prior art. Therefore, an object of the present invention is to provide a pressure related to a low load pressure actuator in the combined drive of a low load pressure actuator and a high load pressure actuator. It is an object of the present invention to provide a hydraulic drive system for a hydraulic working machine capable of realizing a desired combined operation without performing a throttling operation associated with the operation of a high load pressure actuator of a compensation valve.

[0007]

In order to achieve this object, the present invention provides a hydraulic pump, a plurality of actuators driven by pressure oil discharged from the hydraulic pump, and the hydraulic pump supplying the actuators with the hydraulic fluid. And a switching valve for controlling the flow of each pressure oil, each switching valve controlling a flow rate control valve and a pressure compensation for controlling a front-back differential pressure which is a differential pressure between an upstream pressure and a downstream pressure of the flow rate control valve. In a hydraulic drive system for a hydraulic working machine including a valve, the hydraulic pump includes at least a first hydraulic pump and a second hydraulic pump, and controls a flow of pressure oil supplied to a specific actuator of the actuators. The switching valve to
A first switching valve and a second switching valve connected in parallel to each other to the specific actuator, wherein the first switching valve is connected to the first hydraulic pump, and the second switching valve is connected. A valve is connected to the second hydraulic pump, and when the specific actuator and another actuator are combinedly driven, the valve is connected from either one of the first switching valve side and the second switching valve side. A supply regulation means capable of selectively regulating the supply of pressure oil to the specific actuator is provided.

[0008]

Since the present invention has the above-mentioned configuration, for example, the high load pressure actuator is selected as the specific actuator, and the first switching valve relating to this high load pressure actuator is connected to the first hydraulic pump. A second switching valve associated with the high load pressure actuator is connected to the second hydraulic pump.
Further, for example, a switching valve that controls the driving of the low load pressure actuator is connected to the first hydraulic pump.

If such a connection causes a saturation state during combined driving of the low load pressure actuator and the high load pressure actuator, a problem arises in which work efficiency is lowered through the low load pressure actuator. First, the supply regulating means is operated to regulate the supply of the pressure oil from the first switching valve side of the switching valves controlling the high load pressure actuator. As a result, the pressure oil discharged from the first hydraulic pump is supplied to the low load pressure actuator, and the pressure oil supplied from the second hydraulic pump is supplied to the high load pressure actuator via the second switching valve. It is supplied, so that the desired combined driving of the low load pressure actuator and the high load pressure actuator can be performed.

At this time, the pressure compensating valve included in the switching valve for controlling the low load pressure actuator is not affected by the operation of the high load pressure actuator, that is, the throttle operation accompanying the operation of the high load pressure actuator is performed. There is nothing to do. Therefore, the flow rate supplied to the low load pressure actuator can be kept constant, and a decrease in the operating speed of the low load pressure actuator can be suppressed.

It should be noted that the supply regulating means should not be actuated when the high load pressure actuator is independently driven, or when the high load pressure actuator and the low load pressure actuator are combinedly driven when the work efficiency of the low load pressure actuator does not matter so much. It suffices if pressure oil can be supplied from the first switching valve side. As a result, the pressure oil of the first hydraulic pump and the pressure oil of the second hydraulic pump can be combined, or a part of the combined flow rate can be supplied to the high load pressure actuator. It is possible to accelerate.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic drive system for a hydraulic working machine according to the present invention will be described below with reference to the drawings. 1 is a circuit diagram showing a first embodiment corresponding to claims 1 and 2 of the present invention. This first embodiment is applied to, for example, a hydraulic drive system for a hydraulic excavator. As shown in FIG. 1, the first embodiment has a first hydraulic pump, that is, a first variable displacement hydraulic pump 1, a second hydraulic pump, that is, a second variable displacement hydraulic pump 2, and a hydraulic pump. First discharge amount control means for controlling the displacement volume of the hydraulic pump 1, for example, a first electromagnetic regulator 27, and second discharge amount control means for controlling the displacement volume of the hydraulic pump 2, for example, a second electromagnetic regulator 24. And a plurality of actuators such as a boom cylinder 9, an arm cylinder 20, and a bucket cylinder 1.
9, a left traveling motor 18 and a right traveling motor 21 are provided. Of the actuators described above, the boom cylinder 9
Is an actuator that can generate high load pressure.
In this embodiment, the specific actuator is configured.

A switching valve for controlling the drive of the left traveling motor 18, that is, a direction switching valve 14, is provided between the hydraulic pump 1 and the left traveling motor 18 described above. For controlling the flow rate control valve 14a that operates according to the switching signals i1 and i2 that are output in accordance with the operation signal of the operating device 18a, and the differential pressure across the flow rate control valve 14a, which is the difference between the upstream pressure and the downstream pressure. The pressure compensating valve 10 is included.

Similarly, between the hydraulic pump 1 and the bucket cylinder 19, a switching valve for controlling the drive of the bucket cylinder 19, that is, a directional switching valve 15, is provided. The directional switching valve 15 is a bucket operating device. Flow control valve 15a that operates in response to switching signals i3 and i4 output in accordance with the operation signal of 19a, and a pressure compensating valve that controls the differential pressure across the flow control valve 15a, which is the difference between the upstream pressure and the downstream pressure. 11
Includes and.

A first switching valve for controlling the drive of the boom cylinder 9, that is, a directional switching valve 7, is provided between the hydraulic pump 1 and the boom cylinder 9, and this directional switching valve 7 is provided.
Is a flow control valve 7a that operates according to the switching signals i5 and i6 output in accordance with the operation signal of the boom operating device 9a.
And a pressure compensating valve 5 for controlling the differential pressure across the flow control valve 7a, which is the difference between the upstream pressure and the downstream pressure.

A second switching valve for controlling the drive of the boom cylinder 9, that is, a directional switching valve 8 is provided between the other hydraulic pump 2 and the boom cylinder 9, and the directional switching valve 8 is a boom. For controlling the flow rate control valve 8a that operates in response to the switching signals i7 and i8 that are output in accordance with the operation signal of the operating device 9a, and the front-rear differential pressure that is the difference between the upstream pressure and the downstream pressure of the flow rate control valve 8a. The pressure compensating valve 6 is included.
The directional switching valve 8 forming the second switching valve and the directional switching valve 7 forming the first switching valve described above are connected in parallel to the boom cylinder 9.

The hydraulic pump 2 and the arm cylinder 20 are also provided.
A directional control valve for controlling the drive of the arm cylinder 20, that is, a directional control valve 16, is provided between and.
Reference numeral 6 denotes a flow rate control valve 16a that operates in response to switching signals i9 and i10 output in accordance with an operation signal of the arm operating device 20a, and a front-back difference that is a difference between the upstream pressure and the downstream pressure of the flow rate control valve 16a. And a pressure compensating valve 12 for controlling the pressure.

Further, the hydraulic pump 2 and the right traveling motor 21
A switching valve for controlling the drive of the right traveling motor 21, that is, a directional switching valve 17, is provided between and.
Reference numeral 7 is a flow control valve 17a that operates in response to the switching signals i11 and i12 that are output in accordance with the operation signal of the right travel operation device 21a, and the difference between the upstream pressure and the downstream pressure of the flow control valve 17a. And a pressure compensating valve 13 for controlling the differential pressure.

The first embodiment is also provided with a controller 26 having logical judgment and arithmetic functions. This controller 26 includes flow control valves 14, 15, 7, 8, 1
First output means 26 for outputting a signal for controlling 6, 17
a and a second output means 26b for outputting a signal for controlling the regulators 27 and 24.

The first output means 26a is an operating device 18a.
Of the switching signal i whose value increases in accordance with the increase of the value of the operation signal of
1 and i2, the switching signal i3 and i4 whose value increases as the value of the operating signal of the operating device 19a increases, and the switching signal i3 and i4 which increases as the value of the operating signal of the operating device 9a increases. i5, i7, and i6, i8, the relationship between the switching signals i9 and i10, which increases with an increase in the value of the operation signal of the operating device 20a, and the increase with the increase of the value of the operating signal of the operating device 21a. Switching signals i11 and i1
It has a storage unit that stores the relationship of 2 in advance. Further, for example, the boom operating device 9a and the bucket operating device 19a
It has a discriminating means for discriminating whether or not only the operation signal of (b) has been input and whether or not only the operation signals of the boom operating device 9a and the arm operating device 20a have been input. Then, while performing control for outputting a corresponding switching signal from the relationship stored in the above-described storage unit and the operation signal of each operating device 18a, 19a, 9a, 20a, 21a, when performing this control, in particular, the above-mentioned With the discrimination means
When it is determined that only the operation signals of the boom operating device 9a and the bucket operating device 19a are input, the first of the directional control valves 7, 8 that controls the boom cylinder 9 is selected.
The directional control valve 7, which is the directional control valve, is controlled to be kept in a neutral state, and the boom operating device 9a and the arm operating device 20 are controlled.
When it is determined that only the operation signal of a is input, control is performed to maintain the directional control valve 8, which is the second directional control valve of the directional control valves 7 and 8 that controls the boom cylinder 9, in the neutral state. .

The second output means 26b included in the controller 26 has a displacement volume of the hydraulic pump 1 which increases in accordance with an increase in the sum of the values of the switching signals i1 to i6 output from the first output means 26a. And the relationship of the displacement of the hydraulic pump 2 that increases in accordance with the increase in the sum of the values of the switching signals i7 to i12 output from the first output means 26a. Then, the target displacement amount of the hydraulic pump 1 is calculated from the relationship stored in the storage unit and the sum of the values of the corresponding switching signals among the switching signals i1 to i6 output from the first output means 26a. The control is performed to output a drive signal corresponding to the target displacement of the hydraulic pump 1 to the regulator 27, and the relationship stored in the storage unit and the first output means 26a are output. Switching signal i7-
Control is performed to output to the regulator 24 a drive signal corresponding to the target displacement volume of the hydraulic pump 2 from the sum of the corresponding switching signal values of i12.

The first included in the controller 26 described above
The output means 26a of the boom cylinder 9 from the side of the directional switching valve 7 which is the first switching valve when the boom cylinder 9 that is a specific actuator and the other actuator, that is, the bucket cylinder 19 or the arm cylinder 20 are combinedly driven. The supply control means is capable of restricting the supply of pressure oil to the cylinder 9 or the supply of pressure oil to the boom cylinder 9 from the second direction switching valve 8.

The operation of the first embodiment thus constructed will be described below with reference to FIGS. 2 and 3 showing the processing procedure in the controller 26.

For example, the boom operating device 9a and the bucket operating device 18a are provided in order to perform combined drive of the boom cylinder 9 that can form a high load pressure actuator and the bucket cylinder 19 that can form a low load pressure actuator. The case of operation will be described.

First, the operation signals of the boom operating device 9a and the bucket operating device 18a are input to the first output means 26a of the controller 26 as shown in step S1 of FIG. Next, in step S2, it is determined whether or not a boom operation signal is input. Since it has been input, the procedure moves to step S3. In step S3, it is determined whether or not an actuator operation signal other than the boom is input. Since it has been input, the procedure moves to step S4. In step S4, it is determined whether the other actuator operation signals are only arm operation signals. Since the arm operation signal has not been input at this time, the process proceeds to step S8. Step S
At 8, it is determined whether the other actuator operation signals are only bucket operation signals. Since only the bucket operation signal is present at this time, the procedure moves to step S9 shown in FIG.

In step S9, control is performed to stop the output of the switching signals i5 and i6. As a result, the directional switching valve 7 forming the first switching valve is kept in the neutral state. Then, the process proceeds to step S10. In step S10, it is applicable based on the relationship of the switching signal i7 or i8 that increases according to the value of the operation signal of the operation device 9a stored in the storage unit and the operation signal of the operation device 9a that is actually output. The switching signal i7 or i8 is obtained, and at the same time, the switching signal i3 increases according to the value of the operation signal of the operating device 19a stored in the storage unit.
Or the relationship of i4 and the operating device 1 actually output
The corresponding switching signal i3 or i4 is obtained based on the operation signal of 9a, and these switching signals i7 or i8,
And the switching signal i3 or i4 from the first output means 26a of the controller 26 to the drive unit of the flow control valve 15a of the directional control valve 15 and the flow control valve 8a of the directional control valve 8.
Are output to the respective drive units.

After step S10 in FIG. 3 described above,
The procedure moves to step S7 which is a process in the second output means 26b. In step S7, the switching signals i1 to i1 stored in the storage unit are stored.
Based on the relationship between the displacement of the hydraulic pump 1 that increases as the sum of the values of i6 increases and the switching signal i3 or i4 output from the above-mentioned first output means 26a, the target hydraulic pump 1 Displacement volume is required, at the same time,
The relationship between the displacement of the hydraulic pump 2 that increases with an increase in the sum of the values of the switching signals i7 to i12 stored in the storage unit, and the switching signal i7 or i8 output from the above-mentioned first output means 26a. Target hydraulic pump 2 based on
The displacement volume of each of the regulators 27 and 24 is determined by the corresponding drive signal, that is, the pump flow rate control signal.
Is output to.

As described above, when the boom cylinder 9 that can form a high load pressure actuator and the bucket cylinder 19 that can form a low load pressure actuator are combinedly driven, the first switching valve controls the boom cylinder 9. Since the direction switching valve 7 is held in the neutral state, the pressure oil of the hydraulic pump 1 can be supplied to the bucket cylinder 19 via the direction switching valve 15 to drive the bucket cylinder 19, and the pressure oil of the hydraulic pump 2 can be directed. It is possible to supply the boom cylinder 9 through the switching valve 8 and realize a combined drive of the boom cylinder 9 and the bucket cylinder 19. Further, at this time, since the pressure oil of the hydraulic pump 1 is not supplied to the boom cylinder 9 because the direction switching valve 7 is neutral, the pump pressure of the hydraulic pump 1 increases with the high load pressure of the boom cylinder 9. That is, the pressure compensation valve 11 of the directional control valve 15 on the low load side is held without being affected by the high load pressure of the boom cylinder 9. Therefore, the operating speed of the bucket cylinder 19 can be maintained at a predetermined speed according to the operation amount of the bucket operating device 19a, and the operating speed does not decrease.

Further, for example, in order to perform a combined drive of the boom cylinder 9 which can form a high load pressure actuator and the arm cylinder 20 which can form a low load pressure actuator, a boom operating device 9a and an arm operating device 20a. The case where is operated will be described. Also in this case,
Basically, this is the same as the case of the combined drive of the boom cylinder 9 and the bucket cylinder 19 described above.

The boom cylinder 9 and the arm cylinder 2
In the case of the compound drive of 0, it is determined in step S4 of FIG. 2 described above that only the arm operation signal is input, and the process proceeds to step S5 shown in FIG.

In step S5, control is performed to stop the output of the switching signals i7 and i8. As a result, the direction switching valve 8 forming the second switching valve is kept in the neutral state. Then, the process proceeds to step S6. In step S6, the switching signal i5 that increases according to the value of the operation signal of the operating device 9a stored in the storage unit
Or the relationship of i6 and the operating device 9 that is actually output
The corresponding switching signal i5 or i6 is obtained based on the operation signal of a and the operating device 2 stored in the storage unit at the same time.
The relationship between the switching signal i9 or i10 that increases according to the value of the operation signal 0a and the operating device 20 that is actually output.
Based on the operation signal of a, the corresponding switching signal i9 or i10 is obtained, and these switching signals i5 or i6,
And the switching signal i9 or i10 is the controller 26
From the first output means 26a to the drive unit of the flow control valve 7a of the directional control valve 7 and the flow control valve 16 of the directional control valve 16.
It is output to each of the driving units a.

After the step S6 in FIG. 3 described above, the process proceeds to step S7 which is the process in the second output means 26b. In step S7, the switching signals i1 to i1 stored in the storage unit are stored.
Based on the relationship between the displacement of the hydraulic pump 1 that increases with an increase in the sum of the values of i6 and the switching signal i5 or i6 output from the above-mentioned first output means 26a, the target hydraulic pump 1 Displacement volume is required, at the same time,
The relationship between the displacement of the hydraulic pump 2 that increases in accordance with the increase in the sum of the values of the switching signals i7 to i12 stored in the storage unit, and the switching signal i9 or i10 output from the above-mentioned first output means 26a. The target displacement of the hydraulic pump 2 is obtained based on the above, and the corresponding drive signal, that is, the pump flow rate control signal, is output to the regulator 27, 2 respectively.
4 is output.

As described above, during combined driving of the boom cylinder 9 that can form a high load pressure actuator and the arm cylinder 20 that can form a low load pressure actuator,
Since the directional switching valve 8 that is the second switching valve for controlling the boom cylinder 9 is held in the neutral state, the pressure oil of the hydraulic pump 1 is supplied to the boom cylinder 9 via the directional switching valve 7, and the boom cylinder 9 Drive the hydraulic pump 2
Pressure oil is supplied to the arm cylinder 20 via the direction switching valve 16, and the boom cylinder 9 and the arm cylinder 2 are supplied.
A compound drive of 0 can be realized. Further, at this time, as in the case of the combined drive of the boom cylinder 9 and the bucket cylinder 19 at this time, the pressure oil of the hydraulic pump 2 is not supplied to the boom cylinder 9 because the direction switching valve 8 is in the neutral position. The pump pressure of 2 is the boom cylinder 9
Of the directional control valve 16 on the low load side is maintained without being affected by the high load pressure of the boom cylinder 9. Therefore, the operating speed of the arm cylinder 20 can be maintained at a predetermined speed according to the operation amount of the arm operating device 20a, and the operating speed does not decrease.

In the first embodiment, when the boom cylinder 9 is not driven, for example, when the arm cylinder 20 and the bucket cylinder 19 are combinedly driven, the determination in step S2 of FIG. 2 is performed. Next, in step S12 of FIG. 3, a switching signal for switching the flow control valve of the directional control valve of the relevant actuator is output from the first output means 26a of the controller 26. In addition, the boom cylinder 9
3 is also included in the combined drive including the drive of the boom cylinder 9 and the bucket cylinder 19, or the combined drive other than the combined drive of the boom cylinder 9 and the arm cylinder 20, the step S8 of FIG. Step S1 shown in
1, the switching signal for switching the flow control valve of the directional control valve of the corresponding actuator is output from the first output means 26a of the controller 26. During the combined driving as described above, the operation of neutrally holding the directional switching valve 7 that is the first switching valve that controls the boom cylinder 9 or the directional switching valve 8 that is the second switching valve is not performed.

When the boom cylinder 9 is driven independently, the procedure moves from step S3 shown in FIG. 2 to step S13 shown in FIG. 3 in which the switching signal for driving both the direction switching valves 7 and 8 is the first signal from the controller 26. Is output from the output means 26a. In this case, the boom cylinder 9 can be accelerated by the pressure oil of the two hydraulic pumps 1 and 2.

According to the first embodiment thus constructed, the boom cylinder 9 that can form a high load pressure actuator and the bucket cylinder 19 or the arm cylinder 20 that can form a low load pressure actuator are combined. At the time of driving, one of the hydraulic pumps 1 and 2 is supplied to the boom cylinder 9, and the other is supplied to the bucket cylinder 19 or the arm cylinder 20,
As a result, desired composite drive can be performed. At this time, the pressure compensating valves 11 and 12 included in the direction switching valves 15 and 16 that control the bucket cylinder 19 or the arm cylinder 20 that are the low load pressure actuators are
Since the discharge pressure of the hydraulic pump that supplies the pressure oil to the bucket cylinder 19 or the arm cylinder 20 that is a low load pressure actuator does not increase under the influence of the high load pressure accompanying the operation of the boom cylinder 9, the boom cylinder 9 The throttling operation associated with the above operation is not performed, that is, the operation of the boom cylinder 9 is not affected. Therefore, during this combined drive, the bucket cylinder 1
9 or the arm cylinder 20 can be maintained at a constant flow rate, a decrease in the operating speed of the bucket cylinder 19 or the arm cylinder 20 can be suppressed, and the working efficiency during the combined drive can be favorably maintained. .

During the composite drive, the pressure compensating valves 11 and 12 on the bucket cylinder 19 or arm cylinder 20 side, which is a low load pressure actuator, perform a throttle operation accompanying the operation of the boom cylinder 9 which is a high load pressure actuator. Therefore, the heat loss due to the diaphragm operation does not occur, and the energy loss from this viewpoint can be suppressed.

For simplification of description, other actuators such as a swing motor are omitted in FIG. 1 showing the first embodiment, but in an actual hydraulic excavator, for example, a swing motor is always provided. . In consideration of the type of work, the swing motor and the arm cylinder 20 described above may be replaced with the boom cylinder 9 and set to a specific actuator. Even if such a setting is made, the configuration may be similar to that of the first embodiment.

FIG. 4 is a circuit diagram showing a second embodiment corresponding to claims 1, 2, 3, and 4 of the present invention. In the second embodiment, the bucket cylinder 19 is omitted from the illustration of the first embodiment shown in FIG. 1, the first specific actuator is set to the boom cylinder 9, and the second specific actuator is set to the arm. It is set in the cylinder 20. A first switching valve, that is, a directional switching valve 15 for controlling the drive of the boom cylinder 9, and a second switching valve, that is, a directional switching valve 8, are connected in parallel to the boom cylinder 9, and the first switching valve is also connected. The directional switching valve 15 which is a switching valve is connected to the first variable displacement hydraulic pump 1 which is a first hydraulic pump, and the directional switching valve 8 which is a second switching valve is a second hydraulic pump. It is connected to two variable displacement hydraulic pumps 2. Further, a third switching valve, that is, a direction switching valve 7 for controlling the drive of the arm cylinder 20, and a fourth switching valve, that is, a direction switching valve 16, are connected in parallel to the arm cylinder 20, and The directional switching valve 7 which is the switching valve of No. 3 is connected to the first variable displacement hydraulic pump 1 which is the first hydraulic pump, and the directional switching valve 16 which is the fourth switching valve is the second hydraulic pump. It is connected to a second variable displacement hydraulic pump 2. Further, the first output means 26a of the controller 26 controls the relationship between the switching signals i1 and i2, the values of which increase in accordance with the increase in the value of the operation signal of the left traveling operation device 18a, and the operation signal of the boom operation device 9a. Switching signals i3, i4, and i7, which increase with an increase in the value of
i8, the switching signals i5, i6, and i9, which increase in accordance with the increase of the value of the operation signal of the arm operating device 20a.
It has a storage unit that stores in advance the relationship of i10 and the relationship of the switching signals i11 and i12 that increase in accordance with the increase of the value of the operation signal of the right travel operation device 21a. Further, it has a determining means for determining whether or not only the operation signals of the boom operating device 9a and the arm operating device 20a are input.
Then, control is performed to output a corresponding switching signal based on the relationship stored in the storage unit described above and the operation signal of each operating device 19a, 9a, 20a, 21a. With the discrimination means
When it is determined that only the operation signals of the boom operating device 9a and the arm operating device 20a are being input, for example, the direction of the second directional control valve of the directional control valves 15 and 8 that controls the hood cylinder 9 is determined. Control is performed to keep the switching valve 8 in the neutral state, and control is performed to keep the directional switching valve 7, which is the third switching valve of the directional switching valves 7 and 16 that controls the arm cylinder 20, in the neutral state.

First included in the controller 26 described above
When the boom cylinder 9 which is the first specific actuator and the other actuator, that is, the arm cylinder 20 are combined and driven, the output means 26a of the output means 26a from the side of the directional switching valve 8 which is the second switching valve to the boom cylinder 9 is connected. In addition to constituting a first supply regulation means capable of regulating the supply of pressure oil,
Arm cylinder 20 which is the second specific actuator
And a second actuator that can regulate the supply of pressure oil from the side of the directional switching valve 7 that is the third switching valve to the arm cylinder 20 during combined driving with another actuator, that is, the boom cylinder 9.
It constitutes the supply control means.

The other structure is almost the same as that of the first embodiment.

In the second embodiment thus constructed, for example, when the boom cylinder 9 is driven independently, the boom operating device 9a is operated to operate the hydraulic pumps 1 and 2 via both the direction switching valves 15 and 8. Pressure oil is supplied to the boom cylinder 9, which can accelerate the boom cylinder 9. Further, when the arm cylinder 20 is driven independently, the directional control valve 7 is operated by operating the arm operating device 20a.
The pressure oil of the hydraulic pumps 1 and 2 is supplied to both arms 16 to the arm cylinder 20, and the speed of the arm cylinder 20 can be increased.

When the boom cylinder 9 and the arm cylinder 20 are combinedly driven, the boom operating device 9 is operated by the discriminating means included in the first output means 26a of the controller 26.
It is discriminated that only the operation signals of a and the arm operation device 20a are inputted, and thereby control for holding the direction switching valves 7 and 8 in a neutral state is performed, and only the direction switching valves 15 and 16 are operated respectively. It is switched according to the operation amount of 9a, 20a. As a result, the pressure oil of the hydraulic pump 1 becomes the first
Is supplied to the boom cylinder 9 via the directional switching valve 15 which is the switching valve of the hydraulic pump 2, and the pressure oil of the hydraulic pump 2 is supplied to the arm cylinder 20 via the directional switching valve 16 which is the fourth switching valve, and the desired composite Drive can be implemented. At this time, similar to the first embodiment described above, for example, the hydraulic pump 2 for supplying pressure oil to the arm cylinder 20 which is a low load pressure actuator.
Since the discharge pressure of No. 1 does not increase due to the influence of the high load pressure accompanying the operation of the boom cylinder 9, the pressure compensating valve 12 of the directional control valve 16 can perform the throttling operation associated with the operation of the boom cylinder 9. None, that is, it is not affected by the operation of the boom cylinder 9. Therefore,
The flow rate supplied to the arm cylinder 20 during this combined drive can be kept constant, a decrease in the operating speed of this arm cylinder 20 can be suppressed, and work efficiency during the combined drive can be favorably maintained.

In FIG. 4 showing the second embodiment for simplification of explanation, other actuators such as a bucket cylinder and a swing motor, and related directional control valves are not shown. I am doing it.

During the compound drive, the pressure compensating valve 12 on the arm cylinder 20 side, which is a low load pressure actuator, does not perform the throttling operation associated with the operation of the boom cylinder 9 that is a high load pressure actuator. The heat loss due to the diaphragm operation does not occur, and the energy loss from this viewpoint can be suppressed.

FIG. 5 is a circuit diagram showing a third embodiment corresponding to claim 5 of the present invention. Compared with the first embodiment shown in FIG. 1, in the third embodiment shown in FIG. 5, the controller 26 has a first output except for the second output means 26b in the first embodiment. Only the means 26a is provided, and the first and second discharge amount control means for controlling the displacement of the hydraulic pumps 1 and 2 respectively are
First electromagnetic regulator 27, second in the embodiment of
Instead of the electromagnetic regulator 24, a first hydraulic drive type regulator 3 and a second hydraulic drive type regulator 4 are provided.

The regulator 3 directly determines the differential pressure between the discharge pressure of the hydraulic pump 1 and the maximum load pressure which is the largest load pressure among the load pressures of the left traveling motor 18, the bucket cylinder 19 and the boom cylinder 9. In response, the displacement of the hydraulic pump 1 is controlled so that the hydraulic pump 1 discharges a flow rate at which the differential pressure becomes equal to a predetermined set differential pressure. Similarly, the regulator 4 directly determines the differential pressure between the discharge pressure of the hydraulic pump 2 and the maximum load pressure, which is the largest load pressure of the boom cylinder 9, the arm cylinder 20, and the right travel motor 21. In response, the displacement of the hydraulic pump 2 is controlled so that the hydraulic pump 2 discharges a flow rate at which the differential pressure becomes equal to a predetermined set differential pressure.

In the third embodiment, the hydraulic pump 1 and the regulator 3, the direction switching valve 14 and the left traveling motor 1 are used.
8, the direction switching valve 15 and the bucket cylinder 19, the direction switching valve 7 and the boom cylinder 9 constitute one independent load sensing circuit, and the hydraulic pump 2 and the regulator 4 and the direction switching valve 8 are provided. The boom cylinder 9, the direction switching valve 16 and the arm cylinder 20, the direction switching valve 17 and the right traveling motor 21 constitute another independent load sensing circuit.

The other structure is the same as that of the first embodiment described above. Also in the third embodiment configured in this way, for example, the bucket cylinder 19 and the boom cylinder 9
At the time of compound drive of the first embodiment, as in the first embodiment described above, the first
The directional control valve 7 which is the directional control valve is controlled to be neutral, the pressure oil of the hydraulic pump 1 is supplied to the bucket cylinder 19 via the directional control valve 15, and the pressure oil of the hydraulic pump 2 is controlled by the directional control valve 8. It is supplied to the boom cylinder 9 via the, and the combined drive of the bucket cylinder 19 and the boom cylinder 9 can be implemented. At this time, for example, the pressure compensation valve 11 of the direction switching valve 15 that controls the bucket cylinder 19 that is a low load pressure actuator is not affected by the operation of the boom cylinder 9 that is a high load pressure actuator, and the hydraulic pump 1 The load pressure of the boom cylinder 9 is not included in the differential pressure for controlling the regulator 3 of the above, and a flow rate according to the operation amount of the operating device 19a can be supplied to the bucket cylinder 19 via the direction switching valve 15. It is possible to suppress a decrease in the operating speed of the cylinder 19.

Further, for example, when the boom cylinder 9 and the arm cylinder 20 are combinedly driven, the directional switching valve 8 which is the second switching valve is controlled so as to be neutral, similarly to the first embodiment, and the hydraulic pump is operated. The pressure oil of No. 1 is supplied to the boom cylinder 9 via the direction switching valve 7, the pressure oil of the hydraulic pump 2 is supplied to the arm cylinder 20 via the direction switching valve 16, and the combined drive of the boom cylinder 9 and the arm cylinder 20 is performed. Can be implemented. At this time, for example, the direction switching valve 16 for controlling the arm cylinder 20 which is a low load pressure actuator
The pressure compensating valve 12 is not affected by the operation of the boom cylinder 9 that is a high load pressure actuator, and the differential pressure that controls the regulator 4 of the hydraulic pump 2 may include the load pressure of the boom cylinder 9. Without directional valve 1
A flow rate according to the operation amount of the operating device 20a can be supplied to the arm cylinder 20 via 6, and a decrease in the operating speed of the arm cylinder 20 can be suppressed.

When the boom cylinder 9 is driven independently, the directional control valve 7 is operated by operating the operating device 9a.
Both of them can be switched, and the pressure oil of the hydraulic pumps 1 and 2 can be supplied to the boom cylinder 9 to accelerate the boom cylinder 9.

Even in the third embodiment having the above-described structure, as in the first embodiment, when the boom cylinder 9 and the bucket cylinder 19 or the arm cylinder 20 are driven together, a low load pressure actuator is used. The operation of the high load pressure actuator is not affected by the throttling operation of the pressure compensating valve on the side, the decrease in the operating speed of the low load pressure actuator is suppressed, and good work efficiency is obtained. Energy loss can be reduced by suppressing heat loss in the pressure compensation valve.

FIG. 6 is a circuit diagram showing a fourth embodiment corresponding to claim 6 of the present invention. Although the fourth embodiment also includes a load sensing circuit, it differs from the above-described third embodiment shown in FIG. 5 in the following points.

That is, the first point is that, in the above-described third embodiment, the first and second hydraulic drive are the first and second discharge amount control means for controlling the displacement of the hydraulic pumps 1 and 2, respectively. Although the formula regulators 3 and 4 are provided, the fourth embodiment shown in FIG. 6 is provided with the first electromagnetic regulator 27 and the second electromagnetic regulator 24.
The second point is that the differential pressure between the discharge pressure of the hydraulic pump 1 and the maximum load pressure, which is the largest load pressure among the load pressures of the left traveling motor 18, the bucket cylinder 19, and the boom cylinder 9, is detected. 1 differential pressure detector 23 and hydraulic pump 2
Discharge pressure, boom cylinder 9, arm cylinder 20,
The second differential pressure detector 25 detects a differential pressure between the maximum load pressure and the load pressure of the right traveling motor 21.

The third point is that the second point of the controller 26 is
Output means 26b obtains a first deviation between the preset differential pressure stored in advance and the differential pressure detected by the first differential pressure detector 23, and outputs a signal for reducing the first deviation to the regulator 2
7 and outputs the preset differential pressure stored in advance and the second
The second deviation from the differential pressure detected by the differential pressure detector 25 is calculated, and a signal for reducing the second deviation is applied to the regulator 2
This is the point where control to output to 4 is performed.

The other structure is the same as that of the third embodiment described above. In the fourth embodiment, the hydraulic pump 1 and the regulator 27, the direction switching valve 14 and the left travel motor 18, the direction switching valve 15 and the bucket cylinder 19, the direction switching valve 7 and the boom cylinder 9,
The first differential pressure detector 23 and the controller 26 constitute one independent load sensing circuit, and the hydraulic pump 2 and the regulator 24, the directional switching valve 8 and the boom cylinder 9, and the directional switching valve. 16, the arm cylinder 20, the direction switching valve 17, the right traveling motor 21, the second differential pressure detector 25, and the controller 26.
Another independent load sensing circuit is constructed by and.

Also in the fourth embodiment configured as described above, the differentials detected by the regulators 27 and 24 of the hydraulic pumps 1 and 2 are respectively detected by the first differential pressure detector 23 and the second differential pressure detector 25. Except for the point that it is electrically controlled based on the pressure, the same operational effect as that of the above-described third embodiment is obtained.

FIG. 7 is a circuit diagram showing a fifth embodiment corresponding to claims 7 and 8 of the present invention. This fifth embodiment is
In addition to the configuration of the fourth embodiment shown in FIG. 6 described above, a boom cylinder 9 and a second cylinder for controlling the boom cylinder 9 are provided.
As a throttle control means capable of restricting the flow rate of the conduit connecting the directional switching valve 8 which is the switching valve of the solenoid valve 2 in the conduit connecting the directional switching valve 8 and the bottom side chamber of the boom cylinder 9.
8 is provided, and an electromagnetic valve 29 is provided in a pipe line connecting the direction switching valve 8 and the rod side chamber of the boom cylinder 9. Further, the controller 26 is configured to include the third output means 26c. The third output means 26c has a determining means for determining whether or not the operation signal of the flow rate change instruction device 32 is input, and when it is determined that the operation signal of the flow rate change instruction device 32 is input. First, control is performed to output a drive signal for reducing the flow rate supplied from the direction switching valve 8 to the boom cylinder 9 to the solenoid valve 28 or the solenoid valve 29. Other configurations are the same as those in the above-described fourth embodiment.

In the fifth embodiment thus constructed, especially when the flow rate change instruction device 32 is operated during the combined drive of the bucket cylinder 19 and the boom cylinder 9, the directional switching valve which is the first switching valve. 7 is held neutral and the pressure oil of the hydraulic pump 1 passes through the direction switching valve 15 and the bucket cylinder 1
9 and the pressure oil of the hydraulic pump 2 is supplied to the boom cylinder 9 via the directional switching valve 8 that is the second switching valve, and is output to the signal output from the third output means 26c of the controller 26. Depending on the solenoid valve 28 or solenoid valve 2
9 is driven, the flow rate supplied from the direction switching valve 8 to the boom cylinder 9 or the amount of oil returned to the tank 22 is limited, and the operation speed of the boom cylinder 9 is controlled to be slow. According to the fifth embodiment, it is possible to control the operating speed of the boom cylinder 9 that matches well the operating speed of the bucket cylinder 19 according to the type of work.

Other operational effects are the same as those of the above-mentioned fourth embodiment. In addition, in the fifth embodiment, the flow rate of the pipe can be regulated in the pipe connecting the boom cylinder 9 and the directional switching valve 8 that is the second switching valve that controls the boom cylinder 9. Although the throttle control means is provided, when the combined drive of the boom cylinder 9 and the arm cylinder 20 is taken into consideration, the boom cylinder 9 and the directional switching valve that is the first switching valve for controlling the boom cylinder 9 are provided. A throttle control means capable of regulating the flow rate of the pipeline may be provided in the pipeline that connects with 7.

FIG. 8 is a circuit diagram showing a sixth embodiment corresponding to claims 7 and 9 of the present invention. In the sixth embodiment, the direction switching is performed as throttle control means capable of restricting the flow rate of the pipe line connecting the boom cylinder 9 and the direction switching valve 8 which is the second switching valve for controlling the boom cylinder 9. Valve 8
A pilot type control valve 28a is provided in a pipe line connecting the bottom side chamber of the boom cylinder 9 and a pilot type control valve 29a is provided in a pipe line connecting the direction switching valve 8 and the rod side chamber of the boom cylinder 9. is there. Furthermore, a pilot pump 33 for supplying a pilot pressure for switching these pilot type control valves 28a and 29a, and a pilot pressure of this pilot pump 33 are controlled to output a secondary pressure to the drive part of the pilot type control valve 28a. Solenoid valve 30
And a solenoid valve 31 for controlling the pilot pressure of the pilot pump 33 and outputting the secondary pressure to the drive portion of the pilot control valve 29a. Further, the third output means 26c of the controller 26 has, for example, a determining means for determining whether or not the operation signal of the flow rate change instruction device 32 is input, and the operation signal of the flow rate change instruction device 32 is input. When it is determined that the control signal is output to the solenoid valve 30 or the solenoid valve 31, a drive signal for reducing the flow rate supplied from the direction switching valve 8 to the boom cylinder 9 is controlled. Other configurations are the same as those of the fifth embodiment described above.

In the sixth embodiment thus constructed, especially when the flow rate change instructing device 32 is operated during the combined drive of the bucket cylinder 19 and the boom cylinder 9, the same operation as the fifth embodiment described above is performed. The directional control valve 7, which is the first directional control valve, is neutrally held, the pressure oil of the hydraulic pump 1 is supplied to the bucket cylinder 19 via the directional control valve 15, and the pressure oil of the hydraulic pump 2 is supplied to the second directional control valve. Is supplied to the boom cylinder 9 via the directional control valve 8 and the solenoid valve 30 or the solenoid valve 31 is driven according to a signal output from the third output means 26c of the controller 26. The secondary pressure, which is the control pressure, is output to the pilot type control valve 28a or the pilot type control valve 29a as the solenoid valve 30 or the electromagnetic valve 31 is driven, and the pilot type control valve 28a or the pilot type control valve 29a is operated. By the operation, the flow rate supplied from the direction switching valve 8 to the boom cylinder 9 or the amount of oil returned to the tank 22 is limited, and the operation speed of the boom cylinder 9 is controlled to be slow.
Even in the sixth embodiment, the operating speed of the boom cylinder 9 can be controlled so as to match the operating speed of the bucket cylinder 19 in accordance with the type of work, as in the fifth embodiment. . The fifth embodiment is difficult to manufacture because the solenoid valves 28 and 29 for controlling the flow rate of the main pipeline are provided. However, in the sixth embodiment, the flow rate of the main pipeline is controlled by the pilot control valves 28a and 29a. Since the pilot control valve is generally suitable for controlling a large flow rate, the sixth embodiment has a large number of parts as compared with the fifth embodiment described above, but is highly practical.

Other operational effects are the same as those of the above-mentioned fifth embodiment. In the sixth embodiment as well, when the combined drive of the boom cylinder 9 and the arm cylinder 20 is taken into consideration, the boom cylinder 9 and the direction switching that is the first switching valve for controlling the boom cylinder 9 are performed. Pilot control valves 28a, 29a capable of regulating the flow rate of the pipeline may be provided in the pipeline connecting to the valve 7.

[0064]

The hydraulic drive system for a hydraulic working machine according to the present invention comprises:
Due to the above-mentioned configuration, when driving a low-load pressure actuator and a high-load pressure actuator in combination, the pressure compensating valve related to the low-load pressure actuator performs a throttle operation accompanying the operation of the high-load pressure actuator. It is possible to realize a desired composite operation without performing the above-mentioned operation, and it is possible to suppress a decrease in the operating speed of the actuator having a low load pressure during the composite operation, which is good work during the composite drive. It has the effect of ensuring efficiency. In addition, as described above, since the pressure compensation valve related to the low load pressure actuator is not throttled with the operation of the high load pressure actuator during this composite drive,
There is also an effect that the heat loss of the pressure compensating valve related to the low load pressure actuator can be suppressed as compared with the prior art, and the energy loss can be reduced.

[Brief description of drawings]

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

FIG. 2 is a flowchart showing a processing procedure in a controller provided in the first embodiment shown in FIG.

FIG. 3 is a flowchart showing a processing procedure in a controller provided in the first embodiment shown in FIG.

FIG. 4 is a circuit diagram showing a second embodiment of the present invention.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention.

FIG. 6 is a circuit diagram showing a fourth embodiment of the present invention.

FIG. 7 is a circuit diagram showing a fifth embodiment of the present invention.

FIG. 8 is a circuit diagram showing a sixth embodiment of the present invention.

[Explanation of symbols]

1 1st variable displacement hydraulic pump (1st hydraulic pump) 2 2nd variable displacement hydraulic pump (2nd hydraulic pump) 3 1st hydraulic drive type regulator (1st discharge amount control means) 4 2nd Hydraulic drive type regulator (second discharge amount control means) 5 Pressure compensation valve 6 Pressure compensation valve 7 Directional switching valve 7a Flow rate control valve 8 Directional switching valve 8a Flow rate control valve 9 Boom cylinder 9a Boom operating device 10 Pressure compensation valve 11 pressure compensation valve 12 pressure compensation valve 13 pressure compensation valve 14 directional switching valve 14a flow control valve 15 directional switching valve 15a flow control valve 16 directional switching valve 16a flow control valve 17 directional switching valve 17a flow control valve 18 left traveling motor (actuator) ) 18a Left-hand operating device 19 Bucket cylinder (actuator) 19a Bucket operating device 20 Arm cylinder (A 20a Arm operating device 21 Right traveling motor (actuator) 21a Right traveling operating device 22 Tank 23 First differential pressure detector 24 Second electromagnetic regulator (second discharge amount control means) 25 Second Differential pressure detector 26 Controller 26a First output means 26b Second output means 26c Third output means 27 First electromagnetic regulator (first discharge amount control means) 28 Electromagnetic valve 28a Pilot control valve 29 Electromagnetic Valve 29a Pilot type control valve 30 Solenoid valve 31 Solenoid valve 32 Flow rate change instruction device 33 Pilot pump

Claims (9)

[Claims] 1. A hydraulic pump, and a plurality of actuators driven by pressure oil discharged from the hydraulic pump,
A switching valve for controlling the flow of pressure oil supplied from the hydraulic pump to the actuator, each of the switching valves having a flow control valve and a differential pressure between an upstream pressure and a downstream pressure of the flow control valve. In a hydraulic drive system for a hydraulic working machine comprising a pressure compensating valve for controlling a certain differential pressure between the front and rear, the hydraulic pump comprises at least a first hydraulic pump and a second hydraulic pump, and a specific actuator among the actuators is provided. The switching valve that controls the flow of the supplied pressure oil is composed of a first switching valve and a second switching valve that are connected in parallel to each other with respect to the specific actuator. While connecting to the first hydraulic pump, connecting the second switching valve to the second hydraulic pump, and driving the specific actuator and other actuators in combination, A supply regulating means capable of selectively regulating the supply of the pressure oil to the specific actuator from one of the first switching valve side and the second switching valve side is provided. Hydraulic drive device for hydraulic working machine. 2. The hydraulic work according to claim 1, wherein the supply regulating means is means for holding one of the first switching valve and the second switching valve in a neutral state. Hydraulic drive of machine. 3. The other actuator includes a second specific actuator different from the specific actuator, and a switching valve for controlling a flow of pressure oil supplied to the second specific actuator is the second specific actuator. A third switching valve and a fourth switching valve connected in parallel to each other to a specific actuator, wherein the third switching valve is connected to the first hydraulic pump, and the fourth switching valve is connected. Is connected to the second hydraulic pump, and at the time of compound drive including the second specific actuator, the above-mentioned from one of the third switching valve side and the fourth switching valve side is performed. The hydraulic drive system for a hydraulic working machine according to claim 1 or 2, further comprising a second supply regulating means capable of selectively regulating the supply of the pressure oil to the second specific actuator. 4. The second supply regulating means is means for holding one of the third switching valve and the fourth switching valve in a neutral state. Hydraulic drive system for hydraulic work machines. 5. The first hydraulic pump and the second hydraulic pump each comprise a first variable displacement hydraulic pump and a second variable displacement hydraulic pump, and the displacement volume of the first variable displacement hydraulic pump. A first discharge amount control means for controlling the discharge pressure of the first variable displacement hydraulic pump and the load pressure of a plurality of actuators driven by the pressure oil discharged from the first variable displacement hydraulic pump. It is a first hydraulic drive type regulator that directly responds to a pressure difference from the maximum load pressure, and a second discharge amount control means for controlling the displacement of the second variable displacement hydraulic pump is the second It directly responds to the differential pressure between the discharge pressure of the variable displacement hydraulic pump and the maximum load pressure of the load pressures of the plurality of actuators driven by the pressure oil discharged from the second variable displacement hydraulic pump. Hydraulic working machine hydraulic drive system according to any one of claims 1 to 4, characterized in that a second hydraulically driven regulator. 6. The first hydraulic pump and the second hydraulic pump each include a first variable displacement hydraulic pump and a second variable displacement hydraulic pump, and the discharge pressure of the first variable displacement hydraulic pump. A first differential pressure detector for detecting a differential pressure between a maximum load pressure of load pressures of a plurality of actuators driven by pressure oil discharged from the first variable displacement hydraulic pump; A second pressure detecting means for detecting a differential pressure between a discharge pressure of the variable displacement hydraulic pump of No. 2 and a maximum load pressure of load pressures of a plurality of actuators driven by the pressure oil discharged from the second variable displacement hydraulic pump. Differential pressure detector for controlling the displacement of the first variable displacement hydraulic pump, the first discharge amount control means for driving based on a signal output from the first differential pressure detector. First electromagnetic controlled A second regulator for controlling the displacement of the second variable displacement hydraulic pump, the drive of which is controlled based on a signal output from the second differential pressure detector. The hydraulic drive system for a hydraulic working machine according to any one of claims 1 to 4, wherein the hydraulic drive system is an electromagnetic regulator. 7. A throttle control means capable of restricting a flow rate of a pipeline connecting the first switching valve and the specific actuator, and a pipeline connecting the second switching valve and the specific actuator. The hydraulic drive system for a hydraulic working machine according to claim 1 or 2, further comprising at least one throttle control means capable of regulating the flow rate of the above. 8. The hydraulic drive system for a hydraulic working machine according to claim 7, wherein the throttle control means is an electromagnetic valve. 9. The hydraulic drive system for a hydraulic working machine according to claim 7, wherein the throttle control means is a pilot type control valve.