JP2000220168A - Hydraulic control apparatus for construction machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic control apparatus for construction machines that can further increase speed of a specified actuator capable of being driven by the confluence of pressurized oil of two hydraulic pumps. SOLUTION: The apparatus includes a first hydraulic pump 2 and second hydraulic pump 3, an arm cylinder 58 capable of driven by the confluence of pressurized oil respectively discharged from these first hydraulic pump and second hydraulic pump 3, a revolution motor, and a third hydraulic motor for supplying pressurized oil to drive the revolution motor. In this case, a confluence valve 24 is provided for allowing the pressurized oil to be joined to the pressurized oil of the first hydraulic pump and second hydraulic pump 3 to be selectively supplied to the arm cylinder 58, and besides, there are provided with a first pipe conduit 19 for connecting the input ports of a second directional control valve 10 for the arm and first directional control valve for the arm, and a pipe conduit 31 for communicating the part of a center by-path conduit 25 being situated at the upper stream position of the confluence vale 24; then providing at the pipe conduit 31 a check valve 32 for preventing the counterflow of pressurized oil in the direction of the confluence valve 24.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic control device provided in a construction machine such as a hydraulic shovel or the like, and more particularly to a specific actuator which can be driven by the joining of hydraulic oil by two hydraulic pumps, and a specific actuator. The present invention relates to a hydraulic control device for a construction machine including another different actuator and a third hydraulic pump that supplies pressure oil for driving the other actuator.

[0002]

2. Description of the Related Art Some hydraulic control systems for construction machines have conventionally realized the increase in speed of a specific actuator such as an arm cylinder by combining hydraulic oil of two main hydraulic pumps.

In such a situation, recently, in order to secure independence of turning and the like, a turning direction control valve and the like are removed from a pressure oil supply system of the two main hydraulic pumps described above.
The first hydraulic pump, the second hydraulic pump and the second
A hydraulic control device that supplies pressure oil by a third main hydraulic pump provided separately from the hydraulic pump has begun to be proposed.

A conventional technique including the three main hydraulic pumps will be described below with reference to FIGS.

FIG. 5 is a side view showing a hydraulic excavator as an example of a construction machine, and FIG. 6 is a hydraulic circuit diagram showing an example of the configuration of a conventional hydraulic control device provided in the hydraulic excavator shown in FIG.

A hydraulic excavator shown in FIG.
And a revolving body 51 disposed on the traveling body 50, and a boom 5 connected to the revolving body 51 so as to be rotatable in a vertical direction.
2, an arm 53 connected to the tip of the boom 52 so as to be rotatable in the vertical direction, a bucket 54 connected to the tip of the arm 53 so as to be rotatable in the vertical direction, 55. In addition, various actuators, for example, a traveling right motor 56 for driving the traveling body 50 and a traveling left motor (not shown), a rotating motor (not shown) for driving the revolving body 51, a boom cylinder 57 for driving the boom 52, and an arm for driving the arm 53 A cylinder 58, a bucket cylinder 59 for driving the bucket 54, and the like are provided.

As shown in FIG. 6, a hydraulic control device having three main hydraulic pumps provided in such a hydraulic excavator includes an engine 1, a first hydraulic pump 2 driven by the engine 1, and a second hydraulic pump. 3, a third hydraulic pump 4 and a pilot pump 5.

On the center bypass passage 16 communicating with the discharge line 6 of the first hydraulic pump 2, the driving right direction control valve 7 for controlling the driving of the driving right motor 56 and the driving of the bucket cylinder 59 are controlled. Bucket directional control valve 8 and boom first control
A direction control valve 9 and a second arm direction control valve 10 for controlling the driving of the arm cylinder 58 are provided.

An arm cylinder 58 is provided on the center bypass passage 17 communicating with the discharge line 11 of the second hydraulic pump 3.
The first direction control valve 12 for the arm for controlling the drive of the boom, the second direction control valve 13 for the boom for controlling the drive of the boom cylinder 57, the spare direction control valve 14, and the traveling for controlling the driving of the traveling left motor (not shown). A left direction control valve 15 is provided.

The input port of the arm second directional control valve 10 and the input port of the arm first directional control valve 12 are connected by a conduit 19. The flow of pressure oil from the second directional control valve 10 side to the first directional control valve 12 for the arm is permitted, and the first
A check valve 20 for preventing flow from the direction control valve 12 to the second arm direction control valve 10 is provided.

The arm first directional control valve 12 of the two directional control valves related to the drive control of the arm cylinder 58 described above gradually changes the opening area in accordance with the stroke amount of the spool. Things that can be
Although it is composed of a directional control valve having so-called metering characteristics, the second directional control valve 10 for the arm cannot change the size of the opening area gradually in accordance with the stroke amount of the spool, that is, is closed. State
It consists of a directional control valve that can only be selected in one of the states of maintaining an open constant opening area, that is, has no so-called metering characteristics.

The above-mentioned center bypass passage 16 belonging to the hydraulic oil supply system of the first hydraulic pump 2, the traveling right direction control valve 7, the bucket direction control valve 8, and the boom second direction control valve provided on the center bypass passage 16. One-way control valve 9, arm second directional control valve 10, center bypass passage 17 belonging to the hydraulic oil supply system of second hydraulic pump 3, arm first directional control valve provided on center bypass passage 17 12, the boom second directional control valve 13, the spare directional control valve 14, the traveling left directional control valve 15, the line 19 and the check valve 20 are provided in one valve block, that is, the first control valve 18. Have been.

A turning direction control valve 22 for controlling the driving of a turning motor (not shown) and a blade 55 (not shown) for operating the blade 55 are provided on a center bypass passage 25 communicating with the discharge pipe 21 of the third hydraulic pump 4. A blade direction control valve 23 for controlling the driving of the blade cylinder is provided.

The center bypass passage 25 belonging to the hydraulic oil supply system of the third hydraulic pump 4 and the turning direction control valve 2
2, blade direction control valve 23, and third hydraulic pump 4
The relief valve 26 and the like that regulate the discharge pressure of
The second control valve 27 is provided in a valve block provided separately from the control valve 18.

In FIG. 6, reference numeral 29 denotes a pilot relief valve for regulating the discharge pressure of the pilot pump 5, and 58 denotes the aforementioned arm cylinder. In this case, for example, the arm cylinder 58 includes the first hydraulic pump 2 and the second hydraulic pump 3
Are combined to supply a specific actuator. For example, a turning motor (not shown) controlled by the turning direction control valve 22 constitutes another actuator different from the specific actuator described above.

In the prior art constructed as described above, when the arm operating device (not shown) is operated by a predetermined amount, the first directional control valve 12 for the arm and the second directional control valve 10 for the arm are switched so as to interlock with each other. , Second directional control valve for arm 1
0 is switched to a block position for closing the center bypass passage 16. Thereby, the pressure oil of the first hydraulic pump 2 is supplied together with the pressure oil of the second hydraulic pump 3 via the discharge line 6, the center bypass passage 16, the check valve 20, and the line 19 to the first direction control valve for the arm. 12 and supplied. Accordingly, pressure oil corresponding to the switching operation amount of the arm first direction control valve 12 accompanying operation of the arm operating device (not shown) is supplied to the arm cylinder 58, and return oil from the arm cylinder 58 is returned to the tank. Thus, the arm cylinder 58 operates at a relatively high speed by the combined hydraulic oil of the first hydraulic pump 2 and the second hydraulic pump 3.

Further, when the turning operation device (not shown) is operated to drive the turning body and the turning direction control valve 22 is switched, the hydraulic oil of the third hydraulic pump 4 is passed through the turning direction control valve 22. The swing body 51 is supplied to a swing motor (not shown), so that the swing body 51 can swing.

As described above, in the prior art shown in FIGS. 5 and 6, a specific actuator, for example, the arm cylinder 5 is used.
8 is driven by the combined hydraulic oil of the two hydraulic pumps 2 to increase the speed, and the arm cylinder 58 according to the metering characteristic of the first directional control valve 12 for the arm.
Can be controlled. In addition, independence of turning can be secured. Thus, a desired operation such as an excavation operation can be satisfactorily performed.

[0019]

In the above-mentioned prior art, the speed of the arm cylinder 58 can be increased by the confluence of the pressure oils of the first hydraulic pump 2 and the second hydraulic pump 3, and the excavation work can be performed accordingly. Efficiency can be improved. However, in recent night work or the like performed in an urban area or the like, it is particularly required to speed up the work, and therefore, development of a technique for driving an actuator such as an arm cylinder more quickly is desired.

Conventionally, three main hydraulic pumps are provided,
Japanese Patent Laying-Open No. 10-88627 discloses a technique in which two of these main hydraulic pumps can be selectively combined to supply a specific actuator.
Even in the prior art disclosed in this publication, since the pressure oil to be joined to the specific actuator is the pressure oil from the two main hydraulic pumps, it is substantially the same as the prior art shown in FIGS. .

The present invention has been made in view of the above-mentioned situation in the prior art, and an object of the present invention is to realize a further increase in the speed of a specific actuator which can be driven by the joining of hydraulic oils of two hydraulic pumps. An object of the present invention is to provide a hydraulic control device for a construction machine.

[0022]

In order to achieve the above object, according to the first aspect of the present invention, there are provided a first hydraulic pump and a second hydraulic pump, and a first hydraulic pump and a second hydraulic pump.
A specific actuator that can be driven by the merging of hydraulic oil discharged from each of the hydraulic pumps, another actuator different from the specific actuator, and a third hydraulic pump that supplies hydraulic oil to drive the other actuator A hydraulic control device for a construction machine, wherein the hydraulic oil of the third hydraulic pump is combined with the hydraulic oil of the first hydraulic pump and the second hydraulic pump to selectively supply the hydraulic fluid to the specific actuator. The configuration is provided.

According to the first aspect of the present invention, when the junction valve is kept neutral, the hydraulic oil of the first hydraulic pump and the second hydraulic pump can be combined and supplied to the specific actuator. However, the pressure oil of the third hydraulic pump is not merged and supplied to the actuator. Here, when the merge valve is switched from the neutral position, the hydraulic oil of the third hydraulic pump is merged with the hydraulic oil of the first hydraulic pump and the second hydraulic pump by the operation of the merge valve and supplied to the specific actuator. Therefore, the speed of the specific actuator can be increased as compared with the case where only the two hydraulic oils of the first hydraulic pump and the second hydraulic pump are combined. Thus, the pressure oil of the third hydraulic pump can be effectively used for increasing the speed of the specific actuator.

According to a second aspect of the present invention, in the first aspect of the invention, the merging valve is located downstream of the other actuator directional control valve for controlling the driving of the other actuator. It is configured to be provided on a center bypass passage.

According to the second aspect of the present invention, when another directional control valve for the actuator is switched from the neutral position, the hydraulic oil of the third hydraulic pump is supplied to the first hydraulic pump and the second hydraulic pump. Although it is not possible to join the pressure oil of the second hydraulic pump and supply it to the specific actuator, when the other directional control valve for the actuator is kept at the neutral position, the hydraulic oil of the third hydraulic pump is supplied to the first hydraulic pump, It can be combined with the pressure oil of the second hydraulic pump and supplied to a specific actuator, and the speed of this specific actuator can be increased.

In order to achieve the above object, a third aspect of the present invention is the invention according to the first or second aspect, wherein the merging valve is configured to have a metering characteristic. is there.

According to the third aspect of the present invention, since the driving of the specific actuator can be controlled in accordance with the operation amount of the merging valve, the main conduit connected to the specific actuator and the merging valve are separated. Can be connected directly with external piping.

According to a fourth aspect of the present invention, there is provided a directional control valve connected to the first hydraulic pump according to the first aspect of the present invention. A first control valve including a directional control valve connected to the second hydraulic pump; and a second control provided separately from the first control valve and including a directional control valve connected to the third hydraulic pump. And a merging valve provided in the second control valve.

In the invention according to claim 4, the directional control valves required for the construction machine are provided in the two valve blocks of the first control valve and the second control valve. And a confluence valve can be housed, and compactness can be realized.

In order to achieve the above object, a fifth aspect of the present invention is the invention according to any one of the first to fourth aspects, wherein the specific actuator comprises an arm cylinder. .

In order to achieve the above object, the invention according to claim 6 of the present invention is characterized in that:
A first directional control valve for the arm and a second directional control valve for the arm for driving the arm cylinder, wherein one of the first directional control valve for the arm and the second directional control valve for the arm has a metering characteristic; And a directional control valve having no metering characteristic.

According to a seventh aspect of the present invention, there is provided the invention as set forth in any one of the first to sixth aspects, wherein the other actuator comprises a turning motor. I have.

In order to achieve the above object, the invention according to claim 8 of the present invention is characterized in that, in the invention according to any one of claims 1 to 7, the construction machine comprises a hydraulic shovel. .

[0034]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a hydraulic control device for a construction machine according to the present invention will be described below with reference to the drawings. FIG. 1 is a hydraulic circuit diagram showing a configuration of a first embodiment of a hydraulic control device for a construction machine of the present invention, and FIG. 2 is a diagram showing characteristics of a merging valve provided in the first embodiment shown in FIG.

FIG. 1 is drawn in correspondence with FIG. 6 described above, and the same components as those shown in FIG. 6 are denoted by the same reference numerals. That is, the first embodiment shown in FIG. 1 is also provided in, for example, a hydraulic excavator, and includes an engine 1, a first hydraulic pump 2 driven by the engine 1, and a second hydraulic pump 2.
A hydraulic pump 3, a third hydraulic pump 4, and a pilot pump 5 are provided.

On the center bypass passage 16 communicating with the discharge line 6 of the first hydraulic pump 2, a traveling right direction control valve 7 for controlling the driving of the traveling right motor, and the driving of the bucket cylinder 59 shown in FIG. Directional control valve 8 for controlling the boom, the first boom for controlling the drive of the boom cylinder 57
A direction control valve 9 and a second arm direction control valve 10 for controlling the driving of the arm cylinder 58 are arranged.

An arm cylinder 58 is provided on the center bypass passage 17 communicating with the discharge line 11 of the second hydraulic pump 3.
The first direction control valve 12 for the arm for controlling the drive of the boom, the second direction control valve 13 for the boom for controlling the drive of the boom cylinder 57, the spare direction control valve 14, and the traveling for controlling the driving of the traveling left motor (not shown). A left directional control valve 15 is provided.

The input port of the second directional control valve 10 for the arm and the input port of the first directional control valve 12 for the arm are connected by a pipe 19. The flow of pressure oil from the second directional control valve 10 side to the first directional control valve 12 for the arm is permitted, and the first
A check valve 20 for preventing flow from the direction control valve 12 to the second arm direction control valve 10 is provided.

The arm first directional control valve 12 of the two directional control valves relating to the drive control of the arm cylinder 58 described above gradually changes the opening area in accordance with the stroke amount of the spool. Things that can be
Although the directional control valve has a so-called metering characteristic, the second directional control valve 10 for the arm cannot change the size of the opening area gradually according to the stroke amount of the spool, that is, the second directional control valve 10 has an open state. In addition, the directional control valve has a so-called metering characteristic that can be selected only from a state in which a constant opening area is maintained or a state in which it is closed.

The above-mentioned center bypass passage 16 belonging to the pressure oil supply system of the first hydraulic pump 2, the traveling right direction control valve 7, the bucket direction control valve 8, and the boom second direction control valve provided on the center bypass passage 16. One-way control valve 9, arm second directional control valve 10, center bypass passage 17 belonging to the hydraulic oil supply system of second hydraulic pump 3, arm first directional control valve provided on center bypass passage 17 12, the boom second directional control valve 13, the spare directional control valve 14, the traveling left directional control valve 15, the line 19 and the check valve 20 are provided in one valve block, that is, the first control valve 18. It is.

A turning direction control valve 22 for controlling the driving of a not-shown turning motor and a blade 55 shown in FIG. 5 are operated on a center bypass passage 25 communicating with the discharge line 21 of the third hydraulic pump 4. A blade direction control valve 23 for controlling the driving of a blade cylinder (not shown) is provided.

In FIG. 1, reference numeral 29 denotes a pilot relief valve for regulating the discharge pressure of the pilot pump 5, and reference numeral 28 denotes a discharge line of the pilot pump 5. Also in the first embodiment,
For example, the arm cylinder 58 constitutes a specific actuator that can supply the combined pressure oil of the first hydraulic pump 2 and the second hydraulic pump 3. Further, for example, a turning motor (not shown) controlled by the turning direction control valve 22 constitutes another actuator different from the above-mentioned specific actuator, and the turning direction control valve 22 constitutes another actuator direction control valve. ing.

The above structure is the same as that shown in FIG. In the first embodiment of the present invention, in particular, the hydraulic oil of the third hydraulic pump 4 is combined with the hydraulic oil of the first hydraulic pump 2 and the hydraulic oil of the second hydraulic pump 3 so as to be selectively applied to the arm cylinder 58 as a specific actuator. A supply valve 24 is provided.

As shown in FIG. 1, the merging valve 24
For example, it is disposed on the center bypass passage 25 located downstream of the turning direction control valve 22 and the blade direction control valve 23, and is output when an arm operating device (not shown) that operates the arm cylinder 58 is output. The control pilot pressure 30 switches from the open position, which is the neutral position, to the closed position, which is the left position in FIG.
That is, the merging valve 24 does not have metering characteristics, and as shown in FIG. 2, a control pilot pressure 30 smaller than the control pilot pressure SP corresponding to the set force of the spring is applied to the control chamber. 1, the spring is kept at the right position as shown in FIG. When a control pilot pressure 30 greater than the control pilot pressure SP corresponding to the spring setting force is applied to the control chamber, the control chamber is switched to the left position in FIG. The bypass passage 25 is closed.

The merging valve 24 is housed in a second control valve 27 together with, for example, the turning direction control valve 22 and the blade direction control valve 23.

In the first embodiment, a pipe connecting the portion of the pipe 19 located between the input port of the directional control valve 12 for the arm and the check valve 20 and the upstream side of the junction valve 24. A check valve 32 for preventing backflow in the direction of the merger valve 24 is provided in the conduit 31.

In the first embodiment configured as described above, the arm operating device (not shown) is operated by a predetermined amount, and the first directional control valve 12 for the arm and the second directional control valve 10 for the arm are switched so as to be interlocked. At the same time, when the merging valve 24 is switched by the control pilot pressure 30 output in accordance with the operation of the arm operating device, the arm second directional control valve 10 is first switched to the block position where the center bypass passage 16 is closed.

As a result, the pressure oil of the first hydraulic pump 2 is supplied to the discharge line 6, the center bypass passage 16, the check valve 20, the line 1
9 and is supplied to the first direction control valve 12 for the arm together with the pressure oil of the second hydraulic pump 3.

During this time, the merging valve 24 is in the closed position,
The center bypass passage 25 is closed. Thereby, the pressure oil of the third hydraulic pump 4 is guided to the pipeline 31 through the discharge pipeline 21, the center bypass passage 25, the turning direction control valve 21, and the blade direction control valve 23, and further from the pipeline 31. It is supplied to the first arm directional control valve 12 via a conduit 19. That is, the pressure oils of the three main hydraulic pumps of the first hydraulic pump 2, the second hydraulic pump 3, and the third hydraulic pump 4 are combined and supplied to the arm first directional control valve 12 having metering characteristics. Accordingly, the pressure oil corresponding to the switching operation amount of the first arm direction control valve 12 accompanying the operation of the arm operating device (not shown) is supplied to the arm cylinder 58, and the return oil from the arm cylinder 58 is supplied to the first arm control device. It is returned from the directional control valve 12 to the tank via the main line 40. Accordingly, the arm cylinder 58 is driven at a high speed by the combined hydraulic oil of the three main hydraulic pumps of the first hydraulic pump 2, the second hydraulic pump 3, and the third hydraulic pump 4, and the first arm hydraulic pump is used. The directional control valve 12 can be operated at a speed corresponding to the switching operation amount.

For example, when the swing direction control valve 22 is operated to swing the swing body from the state in which the arm cylinder 58 is driven by the combined pressure oil of the three main hydraulic pumps as described above, , Merging valve 24
The pressure oil of the third hydraulic pump 4 is supplied to the turning direction control valve 22 located upstream of the hydraulic pump. Therefore, the pressure oil of the third hydraulic pump 4 is not supplied to the pipeline 31 located downstream of the turning direction control valve 22. In this case, the combined pressure oil of only the first hydraulic pump 2 and the second hydraulic pump 3 is supplied to the arm cylinder 58. That is,
In the first embodiment, the turning operation is preferentially secured.

According to the first embodiment, as described above, the arm cylinder 58 is connected to the three main hydraulic pumps of the first hydraulic pump 2, the second hydraulic pump 3, and the third hydraulic pump 4. And the arm cylinder 58 can be further accelerated. Thereby, work efficiency of excavation work or the like performed via driving of the arm cylinder 58 can be improved.

The merging valve 24 is connected to the turning direction control valve 22.
And the directional control valve 23 for the blade and the merging valve 2
4 is connected to the center bypass passage 25 located between
, The turning priority can be secured.

The merging valve 24 is connected to the turning direction control valve 2.
2. Since it is housed in the second control valve 27 together with the blade directional control valve 23 and the like, a compact valve structure can be achieved, handling of the hydraulic control device during manufacture is easy, and assembly is easy. It is.

FIG. 3 is a hydraulic circuit diagram showing a configuration of a second embodiment of the present invention, and FIG. 4 is a diagram showing characteristics of a merging valve provided in the second embodiment shown in FIG.

The second embodiment shown in FIG. 3 is also provided in a hydraulic shovel, for example. In FIG. 3, the same components as those shown in FIG. 1 described above are denoted by the same reference numerals, but the description thereof will be omitted because they are duplicated.

In the second embodiment, in particular, as shown in FIG. 3, it is arranged downstream of the blade direction control valve 23,
The merging valve 33 included in the second control valve 27 is
It has a characteristic PC of an opening area that enables supply of pressurized oil to the arm cylinder 58 in FIG. 4 and a characteristic PT of an open area that allows outflow of pressurized oil to the tank. In other words, it has a so-called metering characteristic in which the size of the opening area can be gradually changed in accordance with the stroke amount which changes in accordance with the magnitude of the control pilot pressure 30. This converging valve 33 has a metering characteristic that, when the applied control pilot pressure 30 becomes equal to or larger than a predetermined value, increases the flow rate of the supply of the pressure oil of the third hydraulic pump 4 to the arm cylinder 58 almost in proportion. .

Further, a conduit 34 is provided for connecting the actuator port of the merge valve 33 with the main conduit 40 connected to the arm cylinder 58. The pipe 34 is formed of an external pipe disposed below the first control valve 18 and the second control valve 27. A check valve 35 for preventing backflow from the main pipe 40 is provided in the pipe 34. The other configuration is the same as the first configuration shown in FIG.
The configuration is the same as that of the embodiment except for the merging valve 24, the pipeline 31, and the check valve 32.

In the first embodiment thus constructed, the arm operating device (not shown) is operated by a predetermined amount to switch the first directional control valve 12 for the arm and the second directional control valve 10 for the arm in conjunction with each other. At the same time, when the merging valve 33 is switched by the control pilot pressure 30 output in accordance with the operation of the arm operating device, the arm second directional control valve 10 is first switched to the block position where the center bypass passage 16 is closed.

As a result, the pressure oil of the first hydraulic pump 2 is supplied to the discharge line 6, the center bypass passage 16, the check valve 20, the line 1
9 and is supplied to the first direction control valve 12 for the arm together with the pressure oil of the second hydraulic pump 3.

In the meantime, the opening area (characteristic PC in FIG. 4) for enabling the supply of the pressurized oil to the arm cylinder 58 of the merge valve 33 in accordance with the increase in the operation amount of the arm operating device (not shown). Gradually increasing, while the opening area (characteristic P-T in FIG. 4) allowing outflow to the tank gradually decreases,
Gradually, the flow rate supplied from the merger valve 33 to the pipeline 34 increases. The flow supplied to the pipe 34 is determined by the check valve 3
5 via the first directional control valve 12 for the arm
Merge with the flow rate guided to zero. Accordingly, the switching oil amount corresponding to the operation amount of the arm operation device (not shown) corresponding to the operation amount of the arm first direction control valve 12 and the pressure oil corresponding to the magnitude of the switching operation amount of the merging valve 33 pass through the main conduit 40. The oil is supplied to the arm cylinder 58, and the return oil from the arm cylinder 58 is returned to the tank. Thus, the arm cylinder 58 can be driven at a high speed by the combined hydraulic oil of the three main hydraulic pumps of the first hydraulic pump 2, the second hydraulic pump 3, and the third hydraulic pump 4. It can be driven at a speed corresponding to the switching operation fee of the first directional control valve 12 and the switching operation amount of the merge valve 33.

For example, from the state in which the arm cylinder 58 is driven by the combined hydraulic oil of the three main hydraulic pumps, the turning direction control valve shown in FIG. When the switching operation of the turning direction control valve 22 is performed, the turning direction control valve 2
The pressure oil of the third hydraulic pump 4 is supplied to 2. Therefore, no pressure oil is supplied to the junction valve 33 and the pipeline 34 located downstream of the turning direction control valve 22. In this case, the combined pressure oil of only the first hydraulic pump 2 and the second hydraulic pump 3 is supplied to the arm cylinder 58. That is, also in the second embodiment, the turning operation is preferentially secured.

In the second embodiment, the arm cylinder 58 is connected to the first hydraulic pump 2, the second hydraulic pump 3, and the third hydraulic pump 4 in the same manner as in the first embodiment.
The two main hydraulic pumps can be driven by the combined pressure oil, so that the arm cylinder 58 can be further accelerated. Thereby, the work efficiency of the excavation work performed via the drive of the arm cylinder 58 can be improved.

The merging valve 33 is connected to the turning direction control valve 22.
And a main conduit 40 for supplying pressure oil to the arm cylinder 58 with the actuator port of the merge valve 33.
Is provided, the turning priority can be ensured.

Further, as in the first embodiment, the confluence valve 33 is connected to the second control valve 2 together with the turning direction control valve 22 and the blade direction control valve 23.
7, the valve structure can be made compact, the handling of the hydraulic control device at the time of manufacture is easy, and the assembly is simple.

In particular, in the second embodiment, since the merging valve 33 has metering characteristics, even if the merging valve 33 and the main conduit 40 are connected by the conduit 34 constituting the external piping, the arm cylinder 58 movements can be controlled. Therefore, the first control valve 1
8 can be manufactured without complicated labor such as formation of a passage inside. In addition, since it is relatively simple to provide the merging valve 33 in the second control valve 27 and to provide the pipeline 34 constituting the external piping, the existing hydraulic control device as shown in FIG. It can be easily obtained by remodeling.

In the first and second embodiments, the arm cylinder 58 is described as the specific actuator.
In the present invention, the specific actuator is not limited to the arm cylinder 58. For example, the specific actuator is a boom cylinder 57, and the second directional control valve 13 for the boom is used.
Is a directional control valve having no metering characteristic, the first directional control valve 9 for the boom is a directional control valve having the metering characteristic, an input port of the second directional control valve 13 for the boom, and a first directional control for the boom. A pipe for communicating with the input port of the valve 9 is provided, and a check valve for preventing backflow from the boom first directional control valve 9 is provided in the pipe, and the first embodiment shown in FIG. 24, pipeline 3 at
1. Provide a merging valve, a pipeline, and a check valve equivalent to the check valve 32,
The pipe is connected to a pipe connecting the input port of the boom second directional control valve 13 and the input port of the boom first directional control valve 9, or as shown in FIG. 3 described above. Merging valve 33, conduit 3 in the second embodiment
4. Provide a merging valve, a pipeline and a check valve equivalent to the check valve 35,
A configuration in which the pipe is connected to a main pipe connecting the boom first direction control valve 9 and the boom cylinder 57 as an external pipe may be adopted.

In the above-described configuration, similarly to the arm cylinder 58 in the first and second embodiments, three main hydraulic pumps, that is, the first hydraulic pump 2,
The boom cylinder 57 can be driven at a high speed by the combined hydraulic oil of the second hydraulic pump 3 and the third hydraulic pump 4.

[0068]

According to the invention of each claim of the present invention,
The pressure oil of the third hydraulic pump is further combined and supplied to the specific actuator that can be driven by the joining of the two hydraulic pumps, so that the speed of the specific actuator can be further increased, and the working efficiency can be improved as compared with the related art. be able to.

In particular, according to the second aspect of the present invention,
When the directional control valve for another actuator is switched, the specific actuator can be driven by the merging of the pressure oils of the first and second hydraulic pumps, and the other actuator can be driven. When the actuator directional control valve is held neutral, the first, second, and
Driving of the specific actuator by the confluence of the hydraulic oil of the third hydraulic pump can be realized, that is, while the priority operation of the other actuators is ensured, driving of the specific actuator by the confluence of the hydraulic oil of the three hydraulic pumps is selectively performed. Can be realized.

In particular, according to the third aspect of the present invention,
Since the driving of the specific actuator can be suppressed in accordance with the operation amount of the merge valve, the main pipeline connected to the specific actuator and the merge valve can be directly connected by the pipeline constituting the external piping. Can be easily manufactured by modifying an existing hydraulic control device.

In particular, according to the invention of claim 4,
1st control valve, 2nd control valve
Various directional control valves and a junction valve required for the construction machine can be housed in one valve block, so that compactness can be realized and handling during assembly and the like is easy.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram illustrating a configuration of a first embodiment of a hydraulic control device for a construction machine according to the present invention.

FIG. 2 is a view showing characteristics of a merge valve provided in the first embodiment shown in FIG. 1;

FIG. 3 is a hydraulic circuit diagram showing a configuration of a second embodiment of the present invention.

FIG. 4 is a diagram showing characteristics of a merge valve provided in the second embodiment shown in FIG.

FIG. 5 is a side view showing a hydraulic excavator as an example of a construction machine.

6 is a hydraulic circuit diagram showing an example of a configuration of a conventional hydraulic control device provided in the hydraulic excavator shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 2 1st hydraulic pump 3 2nd hydraulic pump 4 3rd hydraulic pump 5 Pilot pump 6 Discharge line 8 Bucket directional control valve 9 Boom 1st directional control valve 10 Arm 2nd directional control valve 11 Discharge line Reference Signs List 12 First directional control valve for arm 13 Second directional control valve for boom 16 Center bypass passage 17 Center bypass passage 18 First control valve 19 Pipeline 20 Check valve 21 Discharge pipeline 22 Turning direction control valve 23 Blade direction Control valve 24 Merge valve 25 Center bypass passage 27 Second control valve 28 Discharge line 30 Control pilot pressure 31 Line 32 Check valve 33 Merge valve 34 Line 35 Check valve 40 Main line 58 Arm cylinder (specific actuator)

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2D003 AA01 AB02 AB03 BA02 BB02 CA05 CA09 DA03 3H089 AA72 BB15 BB20 CC01 CC08 CC11 DA03 DA06 DA13 DB32 DB33 GG02 JJ02

Claims (8)

[Claims] A first hydraulic pump and a second hydraulic pump;
A specific actuator that can be driven by the merging of the pressure oil discharged from each of the first hydraulic pump and the second hydraulic pump, another actuator different from the specific actuator, and a pressure oil that drives the other actuator. In a hydraulic control device for a construction machine having a third hydraulic pump to be supplied, the hydraulic oil of the third hydraulic pump is combined with the hydraulic oil of the first hydraulic pump and the second hydraulic pump to be supplied to the specific actuator. A hydraulic control device for a construction machine, comprising a merging valve that can be selectively supplied. 2. The construction machine according to claim 1, wherein the junction valve is provided on a center bypass passage located downstream of the other actuator directional control valve for controlling the driving of the other actuator. Hydraulic control device. 3. The hydraulic control device for a construction machine according to claim 1, wherein the junction valve has a metering characteristic. 4. A first control valve including a directional control valve connected to the first hydraulic pump and a directional control valve connected to the second hydraulic pump, and provided separately from the first control valve. And a second control valve including a directional control valve connected to the third hydraulic pump, and the merging valve is provided in the second control valve. 3. The hydraulic control device for a construction machine according to claim 1. 5. The hydraulic control device for a construction machine according to claim 1, wherein the specific actuator is an arm cylinder. 6. An arm first directional control valve and an arm second directional control valve for driving the arm cylinder, and one of the arm first directional control valve and the arm second directional control valve. 6. The hydraulic control device for a construction machine according to claim 5, wherein the hydraulic control device comprises a directional control valve having metering characteristics, and the other comprises a directional control valve having no metering characteristics. 7. The hydraulic control device for a construction machine according to claim 1, wherein the other actuator is a turning motor. 8. The hydraulic control device for a construction machine according to claim 1, wherein the construction machine is a hydraulic shovel.