JP2601890B2 - Hydraulic drive for civil and construction machinery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention divides pressure oil of a main hydraulic pump through a plurality of diverting compensation valves to respective actuators provided corresponding to these diverting valves. The present invention relates to a hydraulic drive device for a civil engineering / construction machine capable of performing a desired combined operation by combining and driving these actuators.

<Prior Art> FIG. 10 is a circuit diagram showing a hydraulic shovel hydraulic drive device as an example of this type of conventional hydraulic drive device for civil engineering and construction machinery.

The hydraulic drive device shown in FIG. 10 is driven by a prime mover 1, a variable displacement hydraulic pump driven by the prime mover 1, that is, a main hydraulic pump 2, and a hydraulic oil discharged from the main hydraulic pump 2. A swing motor 3 for rotating a swing body (not shown), and an actuator including a boom cylinder 4 for rotating a boom (not shown).

Further, a flow control valve for controlling the flow of pressure oil supplied from the main hydraulic pump 2 to the swing motor 3, that is, a swing direction control valve 5, and a branch flow compensation for controlling a pressure difference between the front and rear of the swing direction control valve 5 A valve 6, a flow control valve for controlling the flow of the pressure oil supplied from the main hydraulic pump 2 to the boom cylinder 4, that is, a boom directional control valve 7, and a differential pressure between the front and rear of the boom directional control valve 7. And a shunt compensation valve 8.

One of the driving portion 6a of the diverter compensation valve 6, control force Fa ₁ by the pressure and the load pressure of the upstream side of the flow dividing compensation valve 6 is provided such that the shunt compensation valve 6 is opened, the other drive unit 6b , The pressure on the downstream side of the shunt compensation valve 6 and the shuttle valve 9,
The control force Fa due to the maximum load pressure of the circuit led through 10
₂ is provided such that the shunt compensating valve 6 is closed. Similarly, a control force Fb ₁ based on the pressure and the load pressure on the upstream side of the shunt compensation valve 8 is applied to one drive unit 8 a of the shunt compensation valve 8.
The shunt compensation valve 8 is provided so as to be opened, and the other drive unit is provided.
The 8b, the control force Fb ₂ by the maximum load pressure of the pressure and the circuit downstream of the diverter compensating valve 8 is provided such that the shunt compensating valve 8 is closed.

The displacement of the main hydraulic pump 2 is controlled by a control actuator 12 driven by a flow regulating valve 11 which is switched according to the differential pressure between the discharge pressure of the main hydraulic pump 2 and the maximum load pressure of the circuit. Is done.

When the actuator is driven alone, for example, when the swing direction control valve 5 is switched to drive the swing motor 3 to operate a swing body (not shown), the pressure oil discharged from the main hydraulic pump 2 is supplied to the branching compensation valve 6. Is supplied to the turning motor 3 via the turning direction control valve 5. When a change occurs in the load pressure of the turning motor 3, the load pressure is guided to one drive unit 6 a of the shunt compensation valve 6. Thereby, the throttle amount of the branch flow compensating valve 6 is appropriately adjusted, and accordingly, the differential pressure across the turning direction control valve 5 is controlled to be kept constant. That is, the branch flow compensating valve 6 has a function of pressure compensation. This is the same in the diversion compensating valve 8 and the like related to the boom cylinder 4.

In addition, when the actuators are combinedly driven, for example, when the swing motor 3 and the boom cylinder 4 are combinedly driven with different driving pressures, these are operated by operating the swing direction control valve 5 and the boom direction control valve 7. When the required flow rates of the turning direction control valve 5 and the boom direction control valve 7, that is, the total flowable flow rate, exceed the maximum volume of the main hydraulic pump 2, the self-pressure of each actuator and the maximum load pressure of the circuit are set. As a result, the throttle amounts of the diversion compensating valves 6 and 8 are adjusted, and the flow rate guided to the turning direction control valve 5 and the flow rate guided to the boom direction control valve 7 are maintained at a constant flow ratio. Is controlled so as not to exceed the maximum capacity of the main hydraulic pump 2, the front-rear differential pressure between the turning directional control valve 5 and the boom directional control valve 7 is kept equal, and discharged from the main hydraulic pump 2. Pressure The shunt to be supplied to the swing motor 3 and the boom cylinder 4, it is possible to achieve combined operation such as turning the boom raising.

<Problem to be Solved by the Invention> In this conventional hydraulic drive device for civil engineering and construction machinery,
When the swivel motor 3 and the boom cylinder 4 are driven to perform a combined operation of swiveling and boom raising, and work to load earth and sand on a truck or the like is performed, pressure compensation is performed by the diversion compensating valves 6 and 8 as described above. Because of this, the turning motor 3 and the boom cylinder 4 have a turning direction control valve 5,
The flow rate is distributed according to the opening ratio of the boom direction control valve 7. That is, when the strokes of the turning direction control valve 5 and the boom direction control valve 7 are both maximized, the distribution ratio according to the maximum opening at that time is uniquely determined. As a result, the revolving body (not shown) attempts to increase the speed according to the flow rate given by the divided flow. However, since the revolving body has a large inertia, most of the flow rate supplied to the revolving motor 3 escapes from the relief valve and is effective. Not used as energy. At this time, the pressure of the pressure oil discharged from the main hydraulic pump 2 is determined by the acceleration pressure of the swing body and the setting pressure of the relief valve. If this pump pressure is 250Kg / cm
^Assuming it is ² , the pressure required to raise the boom is about 100
Since it is about Kg / cm ² , the difference of 150 Kg / cm ² is throttled by the diversion compensation valve 8 and converted into heat.

Therefore, in the case of the conventional hydraulic drive system, in the combined operation of turning and boom raising, the flow rate is not properly distributed to the actuators, resulting in large energy loss and uneconomical. In particular, since the flow rate supplied to the boom is also unnecessarily distributed to the turn, the amount of rise of the boom is restricted, that is, the boom raising operation is hindered, and the workability is likely to be reduced.

As described above, the situation in which the flow rate distributed to each actuator is uniquely determined irrespective of the work content, causing a problem is not limited to the above-described combined operation of turning and boom raising. This can also occur in a swing pressing excavation operation in which a pressing force is applied to the excavator to perform an excavation operation, a shaping operation in which the ground or the like is flattened, and the like.

For this reason, it is conceivable to change to an optimum shunt ratio according to the work content. In this case, in the conventional case, for example, in the above-described combined operation of turning and boom raising, the boom directional control valve is used. Processing to increase the maximum opening of the spool 7 and processing to limit the spool stroke to reduce the maximum opening of the turning direction control valve 5 are required.

FIG. 11 and FIG. 12 are diagrams showing characteristics associated with the flow division ratio in the above-described combined operation of turning and boom raising. 11, the vertical axis indicates the differential pressure P across the boom directional control valve 7.
1, that is, the differential pressure between the pump pressure and the load pressure of the boom cylinder 4, and the horizontal axis represents the flow rate that can pass through the boom directional control valve 7, that is, the supply flow rate Q1. In addition,
ΔP _LS indicates the pressure difference between the pump pressure and the maximum load pressure of the circuit. A characteristic line 7A shows a characteristic in a normal state where the adjustment of the maximum opening of the boom directional control valve 7 is not performed, and indicates that a relatively small flow rate Q1A can be supplied to the boom directional control valve 7. I have. On the other hand, in the case where the maximum opening of the boom directional control valve 7 is adjusted to be large, the flow rate Q1B larger than the flow rate Q1A is supplied to the boom directional control valve 7 as shown by the characteristic line 7B. It becomes possible.

12, the vertical axis shows the differential pressure P2 before and after the turning direction control valve 5, that is, the differential pressure between the pump pressure and the load pressure of the turning motor 3, and the horizontal axis shows the turning direction control valve 5. , That is, the supply flow rate Q2. Characteristic line 5A
Indicates a normal characteristic in which the maximum opening of the turning direction control valve 2 is not adjusted, and the relatively large flow rate Q2A
Can be supplied to the turning direction control valve 5.
On the other hand, in the case where the maximum opening is adjusted to be small by a process such as limiting the spool stroke of the turning direction control valve 5 or the like, as shown by the characteristic line 5B, the flow rate is compared with the flow rate Q2A. A small flow rate Q2B can be supplied to the turning direction control valve 5.

As described above, even in the conventional hydraulic drive device, by adjusting the maximum opening of the direction control valves 5 and 7,
In the combined operation of turning and boom raising, the flow supplied to the boom cylinder 4 is made relatively large, and the flow supplied to the swing motor 3 is made relatively small, thereby suppressing energy loss and improving workability. It can be realized for the time being.

However, adjusting the maximum opening of the directional control valves 5, 7 and the like as described above is an extremely complicated operation. In addition, the excavation operation, the turning operation, and the boom operation by the combined operation of the normal boom, arm, and bucket are performed. It is not possible to immediately cope with a work change between the work and the like by the combined operation of raising, and therefore it is practically difficult.

In the case where a process for limiting the spool stroke is performed, for example, to reduce the maximum opening of the directional control valve, the characteristic diagram of FIG. 13, that is, the operation lever stroke of the directional control valve and the directional control valve As is clear from the characteristic line 5C showing the relationship with the flow rate that can pass through the valve, compared with the normal metering area S1C where the processing for limiting the spool stroke is not performed, the processing for limiting the spool stroke was performed. In this case, the metering area S2C becomes small, and therefore, the operation area of the operation lever in which the operation speed of the actuator can be changed becomes narrow, and it becomes difficult for the operator to perform the operation.

The present invention has been made in view of the above-described circumstances in the related art, and has an object to provide a civil engineering / construction machine capable of easily distributing an optimum flow rate to each actuator according to the work content in a combined operation. Another object of the present invention is to provide a hydraulic drive device.

<Means for Solving the Problems> In order to achieve this object, the present invention provides a main hydraulic pump, a plurality of actuators driven by pressure oil supplied from the main hydraulic pump, and a supply to these actuators. A flow control valve for controlling the flow of the pressurized oil to be supplied, and a shunt compensation valve for controlling the differential pressure before and after the flow control valve, respectively. In the hydraulic drive system for civil engineering and construction machinery, which is capable of combined driving of these actuators, the pressure of the hydraulic oil discharged from the main hydraulic pump and the maximum of the load pressure of the actuator Differential pressure correction means for correcting the differential pressure from the load pressure according to the type of work performed through the operation of the actuator, and the differential pressure corrected by the differential pressure correction means. Control force applying means for applying a corresponding control force to each of the drive units of the branching compensation valve.

<Operation> In the hydraulic drive device for civil engineering and construction machinery according to the present invention, the control force according to the corrected differential pressure obtained by the differential pressure correction means as described above is controlled by the control force adding means to drive the shunt compensation valve. The control pressure at the time of normal operation according to the differential pressure between the pressure of the hydraulic oil discharged from the main hydraulic pump and the maximum load pressure of the load pressure of the actuator. A large control force or a small control force can be forcibly applied to each drive unit of the shunt compensation valve,
As a result, a flow rate larger or smaller than usual can be supplied to each of the corresponding flow control valves, so that in a combined operation, each actuator is provided with an optimum flow rate according to the work content, and the maximum flow rate of the flow control valve is increased. It can be easily distributed without the need to adjust the degree.

<Example> Hereinafter, a hydraulic drive device of a civil engineering / construction machine according to the present invention will be described with reference to the drawings.

FIG. 1 is a circuit diagram showing a schematic configuration of one embodiment of the present invention.

The first embodiment is provided, for example, in a hydraulic shovel, and includes a main hydraulic pump 20 composed of a variable displacement hydraulic pump.
And a plurality of actuators such as a swivel motor 21 driven by pressure oil supplied from the main hydraulic pump 20 to operate a swivel body (not shown), a boom cylinder 22 to operate a boom (not shown), and a swivel motor 21. A flow control valve for controlling the flow of the supplied pressure oil, that is, a directional control valve for turning.
23, a flow control valve for controlling the flow of pressurized oil supplied to the boom cylinder 22, i.e., a boom directional control valve 24, and a diverting compensation valve 25 for controlling a differential pressure across the turning directional control valve 23.
A diversion compensating valve 26 for controlling the differential pressure across the boom directional control valve 24, and a shuttle valve 27 for detecting the maximum load pressure among the load pressures of the actuators. The configuration is the same as that shown in FIG.

In this embodiment, the pressure of the hydraulic oil discharged from the main hydraulic pump 20 and the above-described maximum load pressure vary depending on the type of work performed through the operation of the actuators such as the swing motor 21 and the boom cylinder 22. includes a differential pressure correction means 28 for correcting the differential pressure [Delta] P _LS with further the pressure difference correction means 28 shunt compensating valve 25 a control force according to the corrected differential pressure,
Control force applying means 29 to be applied to each of the 26 drive units is provided.

The above-mentioned differential pressure correcting means 28 is connected to both the discharge line 30 of the main hydraulic pump 20 and the line connected to the shuttle valve 27, and detects the differential pressure ΔP _LS between the pump pressure and the maximum load pressure. Digging work performed through the operation of actuators such as the differential pressure detecting device 31 that outputs a signal and the swing motor 21 and the boom cylinder 22; special digging work that is performed with special emphasis on work efficiency; Selection device 32 that outputs a selection signal corresponding to the type of work such as work, shaping work, etc.
And the input unit 33, the output unit 34, the storage unit 35, and the differential pressure detection device
A calculation unit for calculating a corrected differential pressure based on the signal output from the selection device 31 and the selection signal output from the selection device 32
It is configured to include a controller 37 having 36.

In addition, the above-described control force adding means 29 includes the above-described controller 37, that is, a storage unit 35 for storing a functional relationship between a predetermined corrected differential pressure and a control force, and an operation for obtaining a control force according to the corrected differential pressure. And a control pressure generating means for generating a control pressure applied to the drive units of the shunt compensation valves 25 and 26 in accordance with a control force signal output from an output unit 34 of the controller 37.
38 is included.

The above-described control pressure generating means 38 includes, for example, a pilot pump 39, and the pilot pump 39 and the branch flow compensating valves 25 and 26.
The output unit of the controller 37 is provided between the
Solenoid valve 4 that operates according to the control force signal output from 34
It is configured to include 1, 42.

Note that one drive unit 25 of each of the branch flow compensating valves 25 and 26 is provided.
a, 26a, the control force by the respective load pressure and control pressure is given to open these shunt compensation valves 25, 26,
In addition, a control force due to the downstream pressure of these shunt compensation valves 25 and 26 is applied to the respective drive units 25b and 26b.
Given to close 5, 26. Also, the main hydraulic pump 2
The displacement of 0 is the differential pressure ΔP between the pump pressure and the maximum load pressure.
_The flow rate is controlled by flow rate control means 43 corresponding to _LS .

The value of the selection signal output from the above-described selection device 32 is predetermined in accordance with the actuator required to execute the corresponding operation, and is, for example, a sediment loading operation by a combined operation of turning and boom raising. Is selected, a correction coefficient α (> 1) for obtaining a corrected differential pressure related to the boom-side divided flow compensating valve 26 and a corrected coefficient α for obtaining the corrected differential pressure related to the swivel-side divided flow compensating valve 25 are obtained. Correction coefficient β (<1)
The selection signal having these values α and β is output to the input unit 33 of the controller 37.

Further, in the storage unit 35 of the controller 37, the functional relationship between the corrected differential pressure and the control force corresponding to the type of work is stored in advance as described above. For the loading operation, a combination of a characteristic line 44 related to the shunt compensation valve 26 and a characteristic line 45 related to the shunt compensation valve 25 in FIG. 3 is stored. The characteristic line 46 is, for example, a characteristic line corresponding to a normal excavation operation, that is, a functional relationship between the differential pressure ΔP _LS and the control force F at the normal time when the forcible drive control of the branch flow compensating valves 25 and 26 is not performed. It shows. Further, a characteristic line 44 shows a relationship between the correction pressure difference α · ΔP _LS (α> 1) larger than the pressure difference ΔP _LS and the control force F,
The characteristic line 45 is a corrected differential pressure β · ΔP smaller than the differential pressure ΔP _LS.
The relationship between _LS (β <1) and the control force F is shown.

In the first embodiment having such a configuration, for example, if the operator selects the sediment loading operation by the selecting device 32 with the intention of performing the sediment loading operation by a combined operation of turning and boom raising, As shown in step S1 of FIG.
(> 1), the selection signal 32 having a beta (<1), and a signal having the detected value [Delta] P _LS in differential pressure detector 31 are read into the arithmetic unit 36 via the input unit 33 of the controller 37. Next, as shown in step S2, the calculation unit 36 calculates the corrected differential pressure, that is, α × ΔP _LS and β × ΔP _LS . Next, the procedure proceeds to step S3, where the relation of FIG. 3 relating to the earth and sand loading operation stored in the storage unit 35 is read into the arithmetic unit 36, and α ·
Control force F1 corresponding to ΔP _LS and control force corresponding to β · ΔP _LS
F2 is required. Next, the procedure proceeds to step S4, where a control force signal corresponding to the above-described control force F1 is output to the solenoid valve 42 shown in FIG. 1, and a control force signal corresponding to the above-described control force F2 is output to the solenoid valve 41.

As a result, the solenoid valve 42 controls the control force F0 based on the differential pressure ΔP _LS.
The opening amount is controlled to be larger than when controlled by a control force signal corresponding to (illustrated in FIG. 3),
On the other hand, the solenoid valve 41 is controlled so that the opening amount becomes small. The pilot pressure discharged from the pilot pump 39 in accordance with the operation of these solenoid valves 42 and 41 causes the control force F to be applied to one drive unit 26a of the shunt compensation valve 26 via the solenoid valve 42.
1, and is guided to one drive unit 25a of the shunt compensation valve 25 via the electromagnetic valve 41 as a control pressure corresponding to the control force F2.
Drives. In this case, one drive unit 26 of the shunt compensation valve 26
Since a control force F1 larger than the normal control force F0 is given to a, the throttle amount is controlled so as to be forcibly reduced, and accordingly, the boom directional control valve 24 has a lower than normal control force. A large flow rate is supplied, and a control force F smaller than the normal control force F0 is applied to one drive unit 25a of the branch flow compensation valve 25.
Since 2 is given, the throttle amount is controlled so as to be forcibly increased, so that a smaller flow rate than usual is supplied to the turning direction control valve 23. FIG. 4 and FIG.
FIG. 4 shows the characteristic at this time. FIG. 4 shows the relationship between the pressure difference P1 between the front and rear of the boom directional control valve 24 and the supply flow rate Q1,
FIG. 5 shows the differential pressure P2 across the turning direction control valve 23 and the supply flow rate Q2.
Shows the relationship. At the boom directional control valve 24 side, during normal operation, that is, in the case of control by the differential pressure ΔP _LS , the relatively small flow rate Q1A as shown by the characteristic line 47A in FIG. At this time, the corrected differential pressure α
P can _LS supplying large flow rate Q1B than the flow rate Q1A as shown in the fourth diagram of characteristic lines 47B in accordance with, and in the turning direction control valve 23 side, when the control of the differential pressure [Delta] P _LS is normal Is a relatively large flow rate Q2A as shown by the characteristic line 48A in FIG.
In the sediment loading work, the flow rate was changed as shown by the characteristic line 48B in FIG. 5 according to the corrected differential pressure α · ΔP _LS .
A flow rate Q2B smaller than Q2A can be supplied.

That is, during the sediment loading operation, a relatively large flow rate can be supplied to the boom cylinder 22 and a relatively small flow rate can be supplied to the swing motor 21 as compared with the normal control, that is, the boom cylinder 22 and the swing motor 21 The optimum flow rate can be distributed according to the sediment loading operation.
The flow to be relieved on the boom side is reduced, and the throttle amount of the boom-side diversion compensating valve 26 is reduced so that the diversion compensating valve 26
Can be suppressed from being converted into heat by the energy of the pressure oil passing therethrough, whereby the energy loss can be suppressed. In addition, since a relatively large flow rate can be supplied to the boom side, the amount of rise of the boom can be sufficiently secured, and excellent workability is provided.

In addition, in the first embodiment, the turning and boom raising operation, that is, the sediment loading operation or the like, which can suppress the energy loss and improve the workability as described above, is performed by using the boom directional control valve 24, A complicated operation of adjusting the spool stroke of the turning direction control valve 23 is not required, and the operation can be realized only by operating the selection device 32, so that it is excellent in following up a change in the operation content.

FIG. 6 is a circuit diagram showing a schematic configuration of the second embodiment of the present invention. The second embodiment is also provided in a hydraulic shovel, and includes an arm cylinder 49 and a bucket cylinder 50 as actuators. The hydraulic cylinder supplied with pressure to the arm cylinder 49 and the bucket cylinder 50 is also provided. A flow control valve for controlling the flow, that is, a direction control valve 51 for the arm and a direction control valve 52 for the bucket, and a branch flow compensation valve 53 for controlling the pressure difference between the front and rear of the direction control valve 51 for the arm and the direction control valve 52 for the bucket. , 54. Other basic configurations are set, for example, to be equal to those of the first embodiment shown in FIG.

Note that the selection device 32 is, for example, a digging operation specifically intended to improve work efficiency as compared with a normal digging operation, that is, when the special digging operation is selected, the correction related to the shunt compensation valve 53 on the arm side. The correction coefficient α (<
A selection signal composed of a combination of 1) and a correction coefficient β (> 1) for obtaining a corrected differential pressure related to the shunt compensating valve 54 on the bucket side is output to the input unit 33 of the controller 37. Is selected, a correction coefficient α (> 1) for obtaining a corrected differential pressure related to the shunt compensation valve 53 on the arm side and a shunt compensation valve 54 on the bucket side are selected. Correction coefficient β for obtaining the corrected differential pressure (<1)
Is input to the input unit 33 of the controller 37.
The storage unit 35 of the controller 37 stores the relationship between the corrected differential pressure and the control force as illustrated in FIG. 3 corresponding to these special excavation work and shaping work. Similar functional relationships are stored in advance.

In the second embodiment configured as described above, when the special excavation work is selected by the selection device 32, the arm-side corrected differential pressure α · calculated by the calculation unit 36 of the controller 37 is used.
Since ΔP _LS (α <1) is smaller than the normal differential pressure ΔP _LS and the bucket-side corrected differential pressure β · ΔP _LS (β> 1) is larger than the normal differential pressure ΔP _LS , the arm side Shunt compensation valve 5
The control force applied to one of the drive units 53a becomes smaller than the control force at the time of normal operation.Thus, as the throttle amount increases, the flow rate supplied to the arm direction control valve 51 becomes relatively small. Also, the control force applied to one driving portion 54a of the bucket-side branch flow compensating valve 54 is larger than the normal control force, so that the throttle amount is reduced and supplied to the bucket direction control valve 52. The operating flow of the arm cylinder 49 is relatively slowed down during the combined operation of the arm and the bucket,
By making the operating speed of the drilling relatively high, it is possible to realize a special drilling operation which is considered to be better in terms of work efficiency than ordinary drilling.

Further, when the shaping operation is selected by the selecting device 32, the arm-side corrected differential pressure α · ΔP _LS (α> 1) obtained by the arithmetic unit 36 of the controller 37 is larger than the normal differential pressure ΔP _LS . Is large, and the bucket-side corrected differential pressure β · ΔP _LS (β <1)
Is smaller than the normal differential pressure ΔP _LS , the control force applied to one drive unit 53a of the arm-side shunt compensation valve 53 is relatively large, contrary to the case of the special excavation work described above.
The control force applied to one drive portion 54a of the bucket side diverting compensation valve 54 is relatively small, so that the flow rate supplied to the arm cylinder 49 via the arm direction control valve 51 is relatively large, and The flow rate supplied to the bucket cylinder 50 via the bucket directional control valve 52 is relatively small, so that the arm speed can be increased while the bucket speed is reduced, so that the work efficiency can be improved, that is, shaping work can be realized. .

Also in the second embodiment, an optimum flow rate according to the type of work can be supplied to the boom cylinder 49 and the bucket cylinder 50, and these combined operations can be easily performed only by operating the selection device 32. And has excellent follow-up performance to changes in work content.

FIG. 7 is a circuit diagram showing a schematic configuration of the third embodiment of the present invention. In the third embodiment, the differential pressure correcting means
28 includes a selection device 32 and a controller 37 that outputs a control signal in accordance with a signal output from the selection device 32, and a control pressure generation unit 38 that constitutes a control force application unit 29.
Is configured to respond to both the pressure difference ΔP _LS between the pump pressure and the maximum load pressure and the control signal output from the controller 37. That is, the solenoid valve 41 constituting the control pressure generating means 38 operates according to the differential pressure ΔP _LS and the control signal from the controller 37, and the first valve described above.
The configuration is such that the differential pressure detecting device as in the first embodiment shown in the figure is omitted. Other configurations are the same as those of the first embodiment, for example.

In the third embodiment configured as described above, the solenoid valve
41 and 42 themselves have a function of detecting the differential pressure ΔP _LS , and therefore, for example, in the case of the earth and sand loading operation, the correction coefficient α described above is output from the output unit 34 of the controller 37 to the drive unit of the solenoid valve 42. A control signal corresponding to (> 1) is output and the solenoid valve
By outputting a control signal corresponding to the above-described correction coefficient β (<1) to the drive unit 41, the correction differential pressure α · ΔP _LS (α> 1), β · ΔP is passed through each of the solenoid valves 42 and 41. _LS (β <
The control pressure corresponding to the control force corresponding to 1) is a shunt compensation valve 2
6 and 25, and perform the same operation as in the first embodiment. With such a configuration, the same effect as that of the first embodiment can be obtained.

FIG. 8 is a circuit diagram showing a schematic configuration of the fourth embodiment of the present invention. In the fourth embodiment, a shunt compensation valve 55 for controlling the pressure difference between the front and rear of the turning direction control valve 23 and a shunt compensation valve 56 for controlling the pressure difference between the front and rear of the boom direction control valve 24 include:
Each of the drive units 55a and 56a is provided with these shunt compensation valves.
Springs 55c, 5 biasing the opening of 55, 56 to open
6c, and the control force by the control force applying means 29 is applied to the other drive units 55b and 56b.
Further, the differential pressure correcting means 28 is connected to the other driving section 55 of the branch flow compensation valve 55.
a switching valve 57 for allowing communication between b and the tank, and a diverting compensation valve 5
Switching valve that allows communication between the other drive unit 56b of 6 and the tank
58. Furthermore, control force adding means
The control force pressure generating means 38 constituting 29 includes variable throttle members 59 and 60 responsive to the differential pressure ΔP _LS , and these variable throttle members 5
For example, throttle valves 61 and 62 provided between the drive units 9 and 60 and the other drive units 55b and 56b of the branch flow compensation valves 55 and 56 are provided. Other configurations are the same as those of the first embodiment shown in FIG.

In the fourth embodiment, the operation amount of the switching valve 57 may be reduced and the operation amount of the switching valve 58 may be increased at the time of the combined operation of turning and boom raising for performing the earth and sand loading operation.
Thereby, the flow rate escaping from the other drive section 56b side of the branch flow compensation valve 56 to the tank is increased by the other drive section 55b of the branch flow compensation valve 55.
The differential pressure ΔP _LS detected by the variable throttle members 59 and 60 is corrected accordingly, and the control pressure capable of providing a control force corresponding to these corrected differential pressures is increased. It is provided to the other drive units 55b, 56b of the shunt compensation valves 55, 56. In this case, as shown in FIG.
Characteristic line 6 for normal operation when 7, 58 are operated by the same operation amount
As compared with 3, the characteristic line 64 relating to the shunt compensation valve 56 has a steeper slope, and a relatively small control force F1 is applied to the other drive unit 56b of the shunt compensation valve 56, thereby reducing the throttle of the shunt compensation valve 56. The flow rate is reduced, and a relatively large flow rate is supplied to the boom directional control valve 24. As shown in FIG. 9, the characteristic line 65 relating to the shunt compensation valve 55 has a gentler slope than the characteristic line 63. And a relatively large control force F2 is applied to the other drive unit 55b of the shunt compensation valve 55, whereby the shunt compensation valve 55
The throttle amount is increased, and a relatively small flow rate is supplied to the turning direction control valve 23. As a result, a large flow rate is supplied compared to the normal state, and a desired combined operation of turning and boom raising can be realized.

In the fourth embodiment, the ratio of the flow rate supplied to the swing motor 21 and the boom cylinder 22 can be changed only by appropriately operating the switching valves 57 and 58, and the same effect as in the first embodiment described above is obtained. To play. Note that, in FIG.
A spring 55 for biasing each of the branching compensation valves 55 and 56 shown in the figure
c, shows 56c force.

In any of the above-described first to fourth embodiments, it is not necessary to adjust the spool stroke of each direction control valve, so that the metering area is not narrowed. There is no hindrance to the operation of the valve.

<Effect of the Invention> Since the hydraulic drive device of the civil engineering / construction machine of the present invention is configured as described above, at the time of the combined operation, the optimum flow rate according to the work content is easily distributed to each actuator. Therefore, it is possible to ensure the suppression of energy loss and the improvement of workability, and to have an excellent followability to a change in work content.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of a hydraulic drive system for a civil engineering and construction machine according to the present invention.
FIG. 2 is a circuit diagram showing a schematic configuration of the first embodiment, FIG. 2 is a flowchart showing a processing procedure performed by a controller provided in the first embodiment, and FIG. 3 is a function relation preset in the first embodiment. FIG. 4 and FIG.
FIG. 6 is a circuit diagram showing a schematic configuration of a second embodiment of the present invention, and FIG.
FIG. 8 is a circuit diagram showing a schematic configuration of a third embodiment of the present invention, FIG. 8 is a circuit diagram showing a schematic configuration of a fourth embodiment of the present invention,
FIG. 9 is a diagram showing characteristics obtained in the fourth embodiment shown in FIG. 8, and FIG. 10 is a circuit diagram showing an example of a conventional hydraulic drive device for civil engineering / construction machinery, FIG. 11, FIG. FIG. 10 is a diagram showing flow characteristics obtained when the spool stroke of the flow control valve is adjusted in the hydraulic drive device shown in FIG. 10, respectively.
FIG. 13 is a diagram for explaining a problem that occurs when the spool stroke of the flow control valve is adjusted in the hydraulic drive device shown in FIG. 20 ... Main hydraulic pump, 21 ... Swing motor, 22 ... Boom cylinder, 23 ... Swing directional control valve, 24 ... Boom directional control valve, 25,26,53,54,55,56 ... Shunt compensator, 25
a, 26a, 55a, 56a ... One drive unit, 25b, 26b, 55b, 5
6b: the other drive unit, 27: shuttle valve, 28: differential pressure correction means, 29: control force adding means, 30: discharge pipe line, 31 ...
... Differential pressure detection device, 32 ... Selection device, 33 ... Input unit, 34 ...
... Output unit, 35 ... Storage unit, 36 ... Calculation unit, 37 ... Controller, 38 ... Control pressure generating means, 39 ... Pilot pump, 41, 42 ... Solenoid valve, 43 ... Flow control means, 49 ……
Arm cylinder, 50 ... Bucket cylinder, 51 ... Arm directional control valve, 52 ... Bucket directional control valve, 55c, 5
6c ... spring, 57, 58 ... switching valve, 59, 60 ... variable throttle member, 61, 62 ... throttle valve.

Claims (9)

(57) [Claims] 1. A main hydraulic pump, a plurality of actuators driven by hydraulic oil supplied from the main hydraulic pump, a flow control valve for controlling a flow of hydraulic oil supplied to the actuators, A flow compensating valve for controlling the pressure difference between the front and rear of the flow control valve, and supplying the hydraulic oil of the main hydraulic pump to each of the actuators via the flow compensating valve and the flow control valve, respectively. In the hydraulic drive device for civil engineering and construction machinery capable of combined driving, the differential pressure between the pressure of the hydraulic oil discharged from the main hydraulic pump and the maximum load pressure among the load pressures of the actuators, Differential pressure correcting means for correcting according to the type of work performed through the operation, and a control force corresponding to the differential pressure corrected by the differential pressure correcting means for controlling the flow dividing compensation valve. Hydraulic drive system for civil engineering and construction machine, characterized in that a control force applying means for applying to each of the moving parts. 2. A differential pressure detecting device for detecting a differential pressure between a pressure of hydraulic oil discharged from a main hydraulic pump and a maximum load pressure of a load pressure of an actuator, and an operation of the actuator. A selection device that outputs a selection signal corresponding to the type of work performed via the CPU, and an operation for obtaining a corrected differential pressure based on the signal output from the differential pressure detection device and the selection signal output from the selection device. A controller having a calculation unit for performing the control, the control force adding means stores a functional relationship between a predetermined corrected differential pressure and the control force, and a calculation for calculating the control force according to the corrected differential pressure And a control pressure generating means for generating a control pressure applied to a drive unit of the shunt compensation valve in accordance with a control force signal output from the controller. Claim (1) civil engineering and construction machine hydraulic drive apparatus wherein. 3. A control pressure generating means is provided between the pilot pump and the driving section of the pilot pump and the diversion compensating valve, and is provided corresponding to each of the diversion compensating valves, and is output from the control. And a solenoid valve that operates in response to the control force signal.
Hydraulic drive for civil engineering and construction machinery as described. 4. A selecting device for outputting a selection signal corresponding to a type of operation performed through the operation of the actuator, and a control signal based on a signal output from the selecting device. And a control force adding means for controlling the pressure difference between the pressure of the hydraulic oil discharged from the main hydraulic pump and the maximum load pressure of the load pressure of the actuator, and a control signal output from the controller. And a control pressure generating means for generating a control pressure applied to a driving portion of the branch flow compensating valve. 5. A control pressure generating means is disposed between the pilot pump and the driving portion of the pilot pump and the flow dividing compensating valve, and is provided corresponding to each of the flow dividing compensating valves. And a solenoid valve responsive to both a differential pressure between the pressure of the pressurized oil and a maximum load pressure among the load pressures of the actuator and a control signal output from the controller. (4) The hydraulic drive device for civil engineering and construction machinery according to (4). 6. A differential pressure compensating means is provided corresponding to each of the flow dividing compensating valves, and includes a switching valve for enabling communication between a drive unit of the flow dividing compensating valve and the tank, and the control force adding means comprises: Control pressure generation that operates by the pressure difference between the pressure of the hydraulic oil discharged from the main hydraulic pump and the maximum load pressure of the load pressure of the actuator to generate the control pressure applied to the drive unit of the shunt compensation valve The hydraulic drive device for a civil engineering / construction machine according to claim 1, further comprising means. 7. A control pressure generating means is disposed between the pilot pump and the driving portion of the pilot pump and the flow dividing compensating valve, and is provided corresponding to each of the flow dividing compensating valves. Throttle members that operate in accordance with the pressure difference between the pressure of the pressurized oil to be performed and the maximum load pressure of the load pressure of the actuator, and a throttle valve provided between the corresponding variable throttle member and the branching compensation valve, respectively. The hydraulic drive device for civil engineering and construction machinery according to claim 6, wherein a downstream of the throttle valve and each of the corresponding switching valves are connected. 8. The civil engineering works according to claim 1, wherein the shunt compensating valve has one of its starting portions forming a receiving portion for receiving a control force for applying a force in a direction to open the shunt compensating valve.・
Hydraulic drive for construction machinery. 9. The shunt compensating valve is characterized in that one of the drive units has a spring for urging the shunt compensator to operate in the opening direction, and a control force is applied to the other drive unit. The hydraulic drive device for civil engineering and construction machinery according to claim 1.