JP2003004002A - Hydraulic actuator drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive unit for synchronizing the strokes of two hydraulic cylinders arranged in series, and to provide a compact and low-cost drive unit. SOLUTION: Two branching passageways 39, 40 are provided in a second electromagnetic hydraulic changeover valve 15. Returning oil flow from a first cylinder 11 is branched at a constant ratio with the branching passageways 39, 40. The constant ratio flow branching is accomplished by introducing the rod side pressure of a second cylinder 12 into a sequence valve 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for controlling the driving of hydraulic actuators, for example, a device for synchronizing the operation of a plurality of hydraulic actuators connected in series.

[0002]

2. Description of the Related Art Generally, in industrial machines and the like, various hydraulic actuators are used to perform work according to the purpose. And, in many cases, a single industrial machine is provided with a plurality of hydraulic actuators, and it is sometimes necessary to coordinate the operation of the separate actuators with each other. Specifically, this is the case as shown in FIG. 4, for example.

FIG. 1 shows, as a hydraulic system diagram, a hydraulic drive system for operating a boom equipped with a bucket, for example. The boom performs, for example, a hoisting operation, and the hoisting operation is performed by expanding and contracting the hydraulic cylinder 1. Further, the bucket is attached to the tip of the boom, and the elevation movement is performed by expanding and contracting the hydraulic cylinder 2. These hydraulic cylinders 1 and 2 are hydraulically arranged in series in order to make the hydraulic circuit simple and efficient. That is, the return oil from the hydraulic cylinder 1 functions as hydraulic oil (pressure oil) for operating the hydraulic cylinder 2.

When the boom is hoisted while the work is loaded on the bucket, it is necessary to keep the bucket horizontal in accordance with the hoisting motion of the boom. Therefore, it is necessary to synchronize the strokes of the hydraulic cylinders 1 and 2. There is. For example, when the boom is laid down, the switching valve 3 is switched and pressure oil is supplied from the hydraulic pump P to the rod side port 4 of the hydraulic cylinder 1, and return oil is returned from the head side port 5. At this time, the bucket needs to be laid down according to the standing of the boom. Therefore, the switching valve 6 is switched and the return oil is sent to the rod side port 7 of the hydraulic cylinder 2. As a result, the return oil is returned from the head side port 8 of the hydraulic cylinder 2.

In such a case, the return oil from the hydraulic cylinder 1 is discharged from the head-side port 5 and is returned to the hydraulic cylinder 2.
However, the stroke of the hydraulic cylinder 2 becomes larger than that of the hydraulic cylinder 1 because the areas on which the hydraulic pressure acts are different between the head side and the rod side. Strokes cannot be synchronized.

For this reason, conventionally, a constant-ratio flow dividing valve 9 as shown in FIG.
The flow is divided at the same ratio as the ratio of the area on the head side of the hydraulic cylinder 1 to the area on the rod side of the hydraulic cylinder 2.
No. 169166, Japanese Utility Model Laid-Open No. 61-198347). As a result, only a part of the return oil from the hydraulic cylinder 1 is sent to the rod side port 7 of the hydraulic cylinder 2, and the strokes of the hydraulic cylinders 1 and 2 can be synchronized.

[0007]

However, in such a structure, it is necessary to separately provide a hydraulic device called the diversion valve 9. The flow dividing valve 9 always divides the flow at a constant ratio regardless of the magnitude of the load pressure on the divided side (the load pressure of the hydraulic cylinder 2). It should be noted that the function of the flow dividing valve 9 is required because if the load pressure on the flow dividing side affects the flow dividing ratio, a large amount of hydraulic oil will flow to the side with a low load, and the required flow dividing will be performed. Because it cannot achieve.

By providing such a diversion valve 9, the hydraulic drive device itself becomes complicated and the cost also rises. Moreover, since the diversion valve 9 is provided, there is a disadvantage that the arrangement of other hydraulic devices and the piping space are restricted.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a simple and inexpensive hydraulic actuator drive device which can divide the supplied hydraulic oil into a fixed ratio and can supply the divided hydraulic oil to a hydraulic actuator. That is.

[0010]

[Means for Solving the Problems] (1) In order to feed hydraulic oil (pressure oil) to a hydraulic actuator, generally, a switching valve for feeding hydraulic oil supplied from a hydraulic pump to a hydraulic actuator is provided. Although adopted, the inventor of the present application has paid attention to the point that the object of the present application can be achieved if the switching valve itself can be provided with a function of dividing hydraulic oil instead of disposing a separate flow dividing valve.

(2) Therefore, a hydraulic actuator drive device according to the present application for achieving the above object is a hydraulic actuator drive device for driving a hydraulic actuator by a hydraulic source that sucks up working oil from an oil tank and supplies the pressurized oil. There is a switching valve that can switch between the first mode in which the supplied pressure oil is returned to the oil tank side or the second mode in which the supplied pressure oil is sent to the hydraulic actuator, and the pilot port through which the external pilot pressure is introduced. And a pressure control valve for generating a predetermined pressure on the downstream side of the switching valve by using an external pilot pressure, the switching valve switching the pressure oil to the second mode in a state of being switched to the second mode. A first branch flow path and a second branch flow path are formed to divide the flow into the hydraulic actuator side and the oil tank side respectively, and the first branch flow path and the second branch flow path are A pilot line for guiding the pressure of the supply side port of the hydraulic actuator to the pilot port of the pressure control valve is provided, each having a throttle having a predetermined throttle area.

According to this structure, the pressure oil supplied from the hydraulic source is returned to the altank when the switching valve is in the first mode, but is sent to the hydraulic actuator when the switching valve is switched to the second mode. It is supplied and the returned oil is returned to the oil tank. At this time, since the pressure control valve is provided, it is possible to generate a predetermined pressure on the downstream side of the switching valve using the external pilot pressure. This external pilot pressure is the pressure at the supply port of the hydraulic actuator,
That is, the pressure of the pressure oil sent from the switching valve to the hydraulic actuator is adopted, and this is guided to the pressure control valve by the pilot line. The pressure of the pressure oil sent to the hydraulic actuator is nothing but the pressure of the first branch flow passage when the switching valve is switched to the second mode.

Therefore, with the switching valve switched to the second mode, the pressure generated in the first branch passage and the pressure generated in the second branch passage can be made similar. Further, since the throttles having a predetermined throttle area are formed in the first and second branch channels, the pressure oil supplied to the switching valve is divided into the first and second branch channels at a ratio corresponding to the ratio of the throttle areas of the both throttles. The flow is divided into the 1-minute flow path and the 2nd flow path.

(3) Further, a hydraulic actuator drive device according to the present application for achieving the above object is a hydraulic actuator drive device for operating a first hydraulic actuator and a second hydraulic actuator which are arranged in series. A hydraulic pump that sucks hydraulic oil from a tank to supply hydraulic oil of a predetermined hydraulic source pressure, and a hydraulic source that has a main hydraulic line that connects the hydraulic pump and the oil tank, and a hydraulic pressure source that is arranged in series in the main hydraulic line. For switching to a first mode in which the hydraulic oil supplied from the oil source is sent to the main hydraulic line or to a second mode in which the hydraulic oil supplied from the hydraulic source is sent to the first hydraulic actuator. Is arranged in series with the first electromagnetic hydraulic pressure switching valve that utilizes the hydraulic pressure source pressure, and in series with the main hydraulic pressure line. Is arranged and is switchable to a first mode for feeding return oil from the first hydraulic actuator to the main hydraulic line or a second mode for feeding return oil from the first hydraulic actuator to the second hydraulic actuator. , A second electromagnetic hydraulic switching valve that uses the hydraulic pressure source pressure for the switching, and a second hydraulic pressure switching valve that is arranged in series with the main hydraulic pressure line and that uses the external pilot pressure to apply a predetermined hydraulic pressure source pressure to the main hydraulic pressure line. And a pressure control valve having a pilot port for generating the pilot oil. The second electromagnetic hydraulic switching valve is configured to switch the second mode to the second mode, in which the return oil is supplied to the second hydraulic actuator, and the main hydraulic pressure is provided. A first branch flow channel and a second branch flow channel are formed in the line, respectively, and each of the first branch flow channel and the second branch flow channel has a throttle having a predetermined throttle area. The pressure of the supply-side ports of the hydraulic actuator is characterized in that the pilot line for guiding the pilot port of the pressure control valve is provided.

According to this structure, the hydraulic pump operates to supply the hydraulic oil (pressure oil) having a predetermined hydraulic source pressure from the hydraulic source. This hydraulic oil is returned to the oil tank of the hydraulic source via the main hydraulic line when the first and second electromagnetic hydraulic switching valves are in the first mode. When the first and second electromagnetic hydraulic switching valves are switched to the second mode, the hydraulic oil is sent to the first hydraulic actuator, and the return oil is sent as it is to the supply side of the second hydraulic actuator.

Since the main hydraulic line is provided with the pressure control valve, a predetermined hydraulic source pressure can always be generated in the main hydraulic line. The hydraulic source pressure generated in the main hydraulic line is used to switch the modes of the first and second electromagnetic hydraulic switching valves. This pressure control valve is of a type that uses an external pilot pressure, and can use, for example, the above hydraulic source pressure.

At this time, when each hydraulic actuator is a hydraulic cylinder or the like, the amount of working oil supplied and the amount of return oil discharged by the cylinder stroke are different, so
If the return oil of the hydraulic actuator is sent as it is to the supply side of the second hydraulic actuator, the operation (stroke) of both hydraulic actuators cannot be synchronized,
In this case, the return oil from the first hydraulic actuator is divided into the first branch passage and the second branch passage of the second electromagnetic hydraulic switching valve before being supplied to the second hydraulic actuator. Then, the hydraulic oil that has flowed into the first branch flow path is fed to the supply port of the second hydraulic actuator, and the hydraulic oil that has flowed into the second branch flow path is returned to the oil tank via the main hydraulic line as it is.

By the way, the second pilot line
Since the pressure of the supply side port of the hydraulic actuator is guided to the pilot port of the pressure control valve, the pressure control valve generates the same pressure as the pressure of the supply side port of the second hydraulic actuator in the main hydraulic line. On the other hand, since the second branch passage is connected to the main hydraulic line, the outlet pressure of the second branch passage is the pressure of the main hydraulic line, that is, the second
The pressure is the same as the pressure at the supply port of the hydraulic actuator. Further, the outlet pressure of the first branch flow passage is similar to the pressure of the supply side port of the second hydraulic actuator. Therefore, the outlet pressure of the first branch channel and the outlet pressure of the second branch channel have the same pressure. In addition, since throttles having a predetermined throttle area are formed in the first and second branch channels, hydraulic oil (return oil from the first hydraulic actuator) is produced at a ratio corresponding to the ratio of the throttle areas of both throttles. Are split into a first branch channel and a second branch channel. That is, the flow is always divided at a constant ratio regardless of the load on the second hydraulic actuator.

Thus, in the case where a hydraulic cylinder is used as the hydraulic actuator, the ratio of the throttle area is made to match the ratio of the head side area and the rod side area on which the hydraulic oil pressure of each hydraulic cylinder acts. ,
The operation (cylinder stroke) of the hydraulic actuators arranged in series can be synchronized.

(4) Further, a hydraulic actuator drive device according to the present application for achieving the above object is a hydraulic actuator drive device for operating a first hydraulic actuator and a second hydraulic actuator arranged in series, A hydraulic pump that sucks hydraulic oil from an oil tank to supply hydraulic oil of a predetermined hydraulic source pressure and a hydraulic source that has a main hydraulic line that connects the hydraulic pump and the oil tank, and is arranged in series in the main hydraulic line, It is possible to switch to a first mode in which the hydraulic oil supplied from the hydraulic pressure source is supplied to the main hydraulic line or a second mode in which the hydraulic oil supplied from the hydraulic source is supplied to the first hydraulic actuator. A first electromagnetic hydraulic pressure switching valve that utilizes the hydraulic pressure source pressure in order to be arranged in series with the first electromagnetic hydraulic pressure switching valve and in series with the main hydraulic pressure line. And is capable of being switched to a first mode in which the return oil from the first hydraulic actuator is fed to the main hydraulic line or a second mode in which the return oil from the first hydraulic actuator is fed to the second hydraulic actuator. And a second electromagnetic hydraulic switching valve that uses the hydraulic source pressure for the switching, and a predetermined hydraulic source pressure that is arranged in series with the main hydraulic line and that uses the external pilot pressure to the main hydraulic line. And a pressure control valve having a pilot port for generating the above-mentioned, and the second electromagnetic hydraulic switching valve has a main port and a main port for supplying the return oil to the second hydraulic actuator in a state of being switched to the second mode. A first branch flow passage and a second branch flow passage are formed in the hydraulic line, respectively, and the first branch flow passage and the second branch flow passage each have a throttle having a predetermined throttle area. The feed-side pressure port of the second hydraulic actuators, 1 of the pressure control valve
It is characterized in that a pilot pressure selecting mechanism for selecting one of the secondary pressure and the hydraulic pressure source pressure and guiding it to the pilot port of the pressure control valve is provided.

According to this structure, the hydraulic pump operates to supply the hydraulic oil (pressure oil) having a predetermined hydraulic source pressure from the hydraulic source. This hydraulic oil is returned to the oil tank of the hydraulic source via the main hydraulic line when the first and second electromagnetic hydraulic switching valves are in the first mode. When the first and second electromagnetic hydraulic switching valves are switched to the second mode, the hydraulic oil is sent to the first hydraulic actuator, and the return oil is sent as it is to the supply side of the second hydraulic actuator.

Since the main hydraulic line is provided with the pressure control valve, a predetermined hydraulic source pressure can always be generated in the main hydraulic line. The hydraulic source pressure generated in the main hydraulic line is used to switch the modes of the first and second electromagnetic hydraulic switching valves. This pressure control valve is of a type that uses an external pilot pressure, and can use, for example, the above hydraulic source pressure.

At this time, when each hydraulic actuator is a hydraulic cylinder or the like, the amount of working oil supplied is different from the amount of return oil discharged by the cylinder stroke.
If the return oil of the hydraulic actuator is sent as it is to the supply side of the second hydraulic actuator, the operation (stroke) of both hydraulic actuators cannot be synchronized,
In this case, the return oil from the first hydraulic actuator is divided into the first branch passage and the second branch passage of the second electromagnetic hydraulic switching valve before being supplied to the second hydraulic actuator. Then, the hydraulic oil that has flowed into the first branch flow path is fed to the supply port of the second hydraulic actuator, and the hydraulic oil that has flowed into the second branch flow path is returned to the oil tank via the main hydraulic line as it is.

By the way, the pilot pressure selecting mechanism selects one of the pressure on the supply side port of the second hydraulic actuator, the primary side pressure of the pressure control valve or the hydraulic source pressure to select the pilot port of the pressure control valve. Can lead to.

First, when the pressure of the supply side port of the second hydraulic actuator is guided to the pilot port of the pressure control valve, the pressure of the supply side port of the second hydraulic actuator is applied to the main hydraulic line by the pressure control valve. Similar pressure is generated. On the other hand, since the second branch flow passage is connected to the main hydraulic pressure line, the outlet pressure of the second branch flow passage becomes the pressure of the main hydraulic pressure line, that is, the pressure of the supply port of the second hydraulic actuator. Further, the outlet pressure of the first branch flow passage is similar to the pressure of the supply side port of the second hydraulic actuator. Therefore, the outlet pressure of the first branch channel and the outlet pressure of the second branch channel have the same pressure. In addition, since throttles having a predetermined throttle area are formed in the first and second branch channels, hydraulic oil (return oil from the first hydraulic actuator) is produced at a ratio corresponding to the ratio of the throttle areas of both throttles. Are split into a first branch channel and a second branch channel. That is, the flow is always divided at a constant ratio regardless of the load on the second hydraulic actuator. As a result, when a hydraulic cylinder is used as a hydraulic actuator, the above-mentioned throttle area ratio is made to match the ratio between the head-side area and the rod-side area on which the hydraulic oil pressure of each hydraulic cylinder acts, so that the serial arrangement is achieved. The operation of the hydraulic actuator (cylinder stroke) can be synchronized.

Next, when the primary side pressure of the pressure control valve is guided to the pilot port of the pressure control valve, the main control hydraulic line is fully closed by the pressure control valve due to the structure of the external pilot type pressure control valve. It Therefore, the return oil from the first hydraulic actuator does not flow to the second branch flow passage,
It is delivered to the supply side port of the hydraulic actuator. Therefore, the high speed operation of the second hydraulic actuator can be performed.

Next, when the hydraulic source pressure is guided to the pilot port of the pressure control valve, the same pressure as the hydraulic source pressure is generated in the main hydraulic line. Therefore, even when the first and second electromagnetic hydraulic switching valves are in the first mode (neutral state), the pressure generated in the main hydraulic line is used for switching the first and second electromagnetic hydraulic switching valves. Can be used.

Here, the pilot pressure selecting mechanism includes a switching valve means having first to third input ports and an output port connected to any one of these input ports, and the second hydraulic actuator. A first pilot line for guiding the pressure of the supply port to the first input port of the switching valve means, and a second pilot line for guiding the primary pressure of the pressure control valve to the second input port of the switching valve means, A third pilot line for guiding the hydraulic source pressure of the main hydraulic line to the third input port of the switching valve means, and a fourth pilot line for guiding the pressure of the output port of the switching valve means to the pilot port of the pressure control valve. Can be configured.

With this configuration, the pressure of the supply port of the second hydraulic actuator is guided to the first input port of the switching valve means by the first pilot line, and the primary pressure of the pressure control valve is adjusted by the second pilot line. Guided to the second input port of the switching valve means, the third pilot line guides the hydraulic pressure source pressure of the main hydraulic line to the third input port of the switching valve means, and the fourth pilot line pressures the output port of the switching valve means. Guide to pilot port of control valve. Then, by switching the switching valve means, one of the pressure of the supply side port of the second hydraulic actuator, the primary side pressure of the pressure control valve or the hydraulic source pressure is selected and pressure controlled through each pilot line. It can lead to the pilot port of the valve.

(5) Further, the pilot pressure selection mechanism includes a switching valve having first and second input ports, an output port connected to one of these input ports, and the two hydraulic actuators. Pilot line that guides the pressure of the supply side port to the first input port of the switching valve, a second pilot line that guides the hydraulic pressure source pressure of the main hydraulic line to the second input port of the switching valve, and the switching A third pilot line that guides the pressure at the output port of the valve to the pilot port of the pressure control valve may be provided.

According to this structure, the pressure of the supply port of the second hydraulic actuator is guided to the first input port of the switching valve by the first pilot line, and the hydraulic source pressure of the main hydraulic line is switched by the second pilot line. To the second input port of the pressure control valve and the pressure of the output port of the switching valve to the pilot port of the pressure control valve by the fourth pilot line. Then, by switching the switching valve, it is possible to select one of the pressure of the supply port of the second hydraulic actuator and the pressure of the hydraulic pressure source through each pilot line and guide the selected pressure to the pilot port of the pressure control valve.

Therefore, either the pressure of the supply port of the second hydraulic actuator or the hydraulic source pressure of the main hydraulic line can be guided to the pressure control valve, and the pressure of the supply port of the second hydraulic actuator can be pressure controlled. When guiding to the valve, the operation of each hydraulic actuator can be synchronized as described above, and when guiding the hydraulic source pressure to the pressure control valve, the switching of each electromagnetic hydraulic switching valve can be performed as described above. The pressure for can be secured.

[0033]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. <First Embodiment> FIG. 1 is a hydraulic system diagram showing the configuration of a hydraulic actuator drive device according to a first embodiment of the present invention.

Description will be made with reference to FIG. This hydraulic actuator drive device (hereinafter, simply referred to as "drive device")
Reference numeral 10 is for operating a first hydraulic cylinder (hereinafter simply referred to as “first cylinder”) 11 and a second hydraulic cylinder (hereinafter simply referred to as “second cylinder”) 12 that are arranged in series. .

Explaining the schematic structure of the drive unit 10, the hydraulic oil (pressure oil) supplied from the hydraulic pressure source 13 is sent to the first cylinder 11 by the first electromagnetic hydraulic switching valve 14, and the return oil is the second oil. Second by the electromagnetic hydraulic switching valve 15
It is adapted to be fed to the cylinder 12. The electromagnetic hydraulic switching valves 14 and 15 are directional switching valves, but the internal spool for switching the direction is of a type that is moved by utilizing the pressure of the hydraulic power source 13. A sequence valve 20 (pressure control valve) is provided to secure the pressure for switching the internal spool.

The cylinders 11 and 12 carry out strokes to perform the required work by the hydraulic oil sent from the electromagnetic hydraulic switching valves 14 and 15. The pilot line 45, which will be described in detail later, allows the second cylinder 12 to operate. The pressure of the hydraulic oil to be supplied to the sequence valve 20 is guided to the sequence valve 20, and the stroke of each cylinder 11, 12 is synchronized by this action. The details will be described below.

(1) Hydraulic pressure source The hydraulic pressure source 13 mainly functions as a power source for operating the cylinders 11, 12, but as a pressure source for switching the internal spools of the electromagnetic switching valves 14, 15 described above. Also works.

The hydraulic pressure source 13 includes a hydraulic pump 16, an oil tank 17, a main hydraulic line 18 connecting them,
It has a spool switching pressure supply unit 19.

The hydraulic pump 16 sucks hydraulic oil from the oil tank 17 and discharges hydraulic oil of a predetermined pressure. This pressure oil is sent to the main hydraulic line 18 and finally returned to the oil tank 17.

The main hydraulic line 18 includes a relief valve 43,
It has the above sequence valve 20. Relief valve 43
Is a safety valve which is arranged in parallel so as to connect the upstream side and the downstream side of the main hydraulic line 18 and which prevents an abnormally high pressure from being generated in the hydraulic system of the drive device 10.

The sequence valve 20 is arranged in series with the main hydraulic pressure line 18 and is for generating a predetermined pressure in the main hydraulic pressure line 18 even when the cylinders 11 and 12 are in an unloaded state. is there. This predetermined pressure is applied to each electromagnetic hydraulic switching valve 14 via the spool switching pressure supply unit 19,
Used as pressure to switch 15 internal spools. Further, the sequence valve 20 is configured such that the predetermined pressure is determined by the external pilot pressure,
A pilot port 21 for guiding the external pilot pressure is provided. The pressure introduced to the pilot port 21 will be described later.

The spool switching pressure supply unit 19 includes a pressure reducing valve 44.
And a pilot pressure introducing line 22 that connects the primary side port of the pressure reducing valve 44 and the upstream side of the main hydraulic pressure line 18, the secondary side port of the pressure reducing valve 44, and the spool switching ports of the electromagnetic hydraulic switching valves 14 and 15. And a pilot pressure supply line 23 for connecting to. The pressure reducing valve 44 is used because the hydraulic pump 1 is used as pilot pressure for spool switching.
The case where the pressure supplied from 6 is too high to be used as it is is taken into consideration, but if there is no problem, the pressure reducing valve 44 may be omitted.

(2) Electromagnetic Hydraulic Changeover Valve The first electromagnetic hydraulic changeover valve 14 has first to third ports 24 to 26 into which hydraulic oil flows and fourth to sixth ports 27 to 29 from which hydraulic oil flows out. It is possible to switch and feed the inflowing hydraulic oil in three directions.

That is, the first electromagnetic hydraulic switching valve 14 has the A
It is possible to switch between the mode (first mode) and the B or C mode (second mode), and in the state of A mode (the state shown in FIG. 1), the hydraulic oil flows from the first port 24 to the fourth port 27, It is fed as it is to the downstream side of the main hydraulic line 18. Further, when the state is switched to the B mode, the hydraulic oil flows from the second port 25 to the sixth port 29 and is sent to the head side port 30 of the first cylinder 11. At this time, the return oil from the first cylinder 11 is returned to the main hydraulic line 18 from the rod side port 31 through the fifth port 28 and the fourth port 27. Further, when the state is switched to the C mode state, the hydraulic oil flows from the second port 25 to the fifth port 28 and is fed to the rod side port 31 of the first cylinder 11. At this time, the return oil from the first cylinder 11 flows from the head side port 30 to the sixth port 29 and the fourth port 29.
It is returned to the main hydraulic line 18 via the port 27.

The second electromagnetic hydraulic switching valve 15 is provided with first to third ports 32 to 34 through which hydraulic oil flows in and fourth to sixth ports 35 to 37 through which hydraulic oil flows out. Oil can be sent by switching in three directions.

That is, the second electromagnetic hydraulic switching valve 15 is
It is possible to switch between the mode (first mode) and the B or C mode (second mode), and in the state of A mode (the state shown in FIG. 1), the hydraulic oil flows from the first port 32 to the fourth port 35, It is fed as it is to the downstream side of the main hydraulic line 18.

When the mode is switched to the B mode, the hydraulic oil flows in from the first and second ports 32 and 33 and flows out from the fourth and fifth ports 35 and 36. That is, in the state in which the second electromagnetic hydraulic switching valve 15 is switched to the B mode, the first branch flow passage 39 and the second branch flow passage 40 are formed therein, and the second port 3
The hydraulic oil flowing in from No. 3 passes through the first branch flow passage 39 and then flows into the second
The hydraulic oil sent to the rod side port 41 of the cylinder 12 and flowing in from the first port 32 passes through the second branch passage 40 and is returned to the main hydraulic line 18. At this time, the return oil from the second cylinder 12 is returned from the head side port 42 to the main hydraulic oil tank 17 via the sixth port 37 and the third port 34.

The first branch channel 39 and the second branch channel 40 are
It has diaphragms 46 and 47 inside. The ratio of the diaphragm area of the diaphragm 46 to the diaphragm area of the diaphragm 47 is set to be equal to the ratio of the rod-side effective area of the second cylinder 12 to the head-side effective area of the first cylinder 11. . Here, the "effective area" generally means an area where the hydraulic oil pressure effectively acts in the cylinder, and the head-side effective area becomes larger than the rod-side effective area by the rod cross-sectional area.

The function and effect of these diaphragms 46 and 47 will be described later. The first branch flow channel 39 and the second branch flow channel 40 are easily formed by changing the shape of the internal spool of the second electromagnetic hydraulic switching valve 15 (for example, forming a required annular groove in the internal spool). be able to.

Further, when the second electromagnetic hydraulic switching valve 15 is switched to the C mode, the working oil flows from the second port 33 to the sixth port 37 and is sent to the head side port 42 of the second cylinder 11. It At this time, the return oil from the second cylinder 11 flows from the rod side port 41 to the fifth port 36.
Then, it is returned to the oil tank 17 via the third port 34.

(3) Pilot line The pilot line 45 guides the pressure of the rod side port 41 of the second cylinder 12 to the pilot port 21 of the sequence valve 20. In the present embodiment, the pilot line 45 has a high pressure priority type shuttle valve 48 and a connection line 49 connected thereto.

The high pressure priority type shuttle valve 48 compares the pressure of the rod side port 41 of the second cylinder 12 with the pressure of the secondary side port of the pressure reducing valve 44 and selects the high pressure side. Then, the selected pressure is guided to the pilot port 21 of the sequence valve 20 by the connection line 49.

(4) Operation of Driving Device Next, the operation of the driving device 10 according to this embodiment will be described.
The operation and effect of each part will be described.

When the hydraulic pump 16 operates, hydraulic oil of a predetermined pressure (hydraulic pressure) is supplied from the hydraulic power source 13. This hydraulic oil is supplied to the first and second electromagnetic hydraulic switching valves 1
When 4 and 15 are in the A mode, they are returned to the oil tank 17 via the main hydraulic line 18. At this time, the secondary pressure of the pressure reducing valve 44 of the spool switching pressure supply unit 19 is guided to the high pressure priority type shuttle valve 48, and the second cylinder 12 is not operating. Are led to the sequence valve 20. Therefore, in the main hydraulic pressure line 18, almost the same pressure as the secondary pressure of the pressure reducing valve 44 is generated. This means that at the same time, the main hydraulic line 18
It means that a predetermined pressure is generated in the pilot pressure supply line 23 based on the pressure generated in the first and second internal pressures of the first and second electromagnetic hydraulic switching valves 14 and 15. To do. That is, even when the first and second electromagnetic hydraulic switching valves 14 and 15 are in the neutral state (A mode), the first and second electromagnetic hydraulic switching valves 14 and 15 can be operated to switch the direction of the hydraulic oil. it can.

Next, when the first electromagnetic hydraulic switching valve 14 is switched to the C mode and the second electromagnetic hydraulic switching valve 15 is switched to the B mode, the return oil of the first cylinder 11 is returned to the second cylinder 12. It is fed to the rod side port 41.

At this time, since the effective area on the head side of the first cylinder 11 and the effective area on the rod side of the second cylinder 12 are different, the entire amount of return oil from the first cylinder 11 is tentatively sent to the second cylinder 12. Then, the stroke of the second cylinder 12 becomes faster than the stroke of the first cylinder 11.

However, in this embodiment, the first cylinder 1
The return oil from No. 1 is divided into the first branch passage 39 and the second branch passage 40 of the second electromagnetic hydraulic switching valve 15 before being sent to the second cylinder 12. Then, the return oil flowing into the first branch flow passage 39 is fed to the rod side port 41 of the second cylinder 12, and the return oil flowing into the second branch flow passage 40 is fed to the main hydraulic line 18 as it is.

Further, at this time, the pressure of the rod side port 41 of the second cylinder 12 and the secondary pressure of the pressure reducing valve 44 are introduced to the high pressure priority type shuttle valve 48. Comparing the two, the pressure of the rod side port 41 of the second cylinder 12 is higher, so the pressure is introduced to the pilot port of the sequence valve 20 by the connection line 49 of the pilot line 45. Therefore, the sequence valve 20 generates a pressure in the main hydraulic line 18 that is substantially the same as the pressure of the rod side port 41 of the second cylinder 12.

On the other hand, the second branch passage 40 is connected to the main hydraulic line 18
Therefore, the outlet pressure of the second branch flow channel 40 is
The pressure is the same as that of the main hydraulic line 18. That is, the outlet pressure of the second branch flow channel 40 becomes the same pressure as the pressure of the rod side port 41 of the second cylinder 12. The outlet pressure of the first branch flow passage 39 is equal to the pressure of the rod side port 41 of the second cylinder 12. Therefore, the outlet pressure of the first branch channel 39 and the outlet pressure of the second branch channel 40 have the same pressure. Moreover, the diaphragms 46 and 47 formed in the first and second branch channels 39 and 40 respectively have a predetermined diaphragm area, and the ratio of the diaphragm area of the diaphragm 46 to the diaphragm area of the diaphragm 47 is the second. It is set to be equal to the ratio of the rod-side effective area of the cylinder 12 and the head-side effective area of the first cylinder 11.

In this embodiment, however, the first cylinder 11 and the second cylinder 12 have the same structure, and the operating speeds of the two cylinders 11 and 12 are the same. Therefore, as described above, the throttle 46 is used. , 47 are made equal to the ratio of the effective area on the head side of the first cylinder 11 and the effective area on the rod side of the second cylinder 12, but in other cases, for example, the first cylinder 11 and the second cylinder 1
When the configurations of 2 are different, the diaphragms 46 and 4 are accordingly changed.
Of course, it is possible to change the design of the aperture area ratio of No. 7.

Therefore, the return oil from the first cylinder 11 is always diverted at a constant ratio by the respective branch passages 39 and 40 and the throttles 46 and 47 regardless of the load of the second cylinder 12, and the first oil is returned to the first cylinder 11. Only the amount obtained by multiplying the total amount of return oil by the ratio of the head-side effective area of the first cylinder 11 to the rod-side effective area of the second cylinder 12 is fed to the branch passage 39. That is, the same amount of return oil as the amount of hydraulic oil sent to the rod side of the first cylinder 11 is sent to the rod side of the second cylinder 12.

As a result, the operations (strokes) of the first and second cylinders 11 and 12 arranged in series can be synchronized.

As described above, according to this embodiment, the strokes of the first and second cylinders 11 and 12 arranged in series can be synchronized, but the return oil from the first cylinder 11 can be used as the second cylinder 12. In order to supply to the drive device, since the constant-ratio diversion is performed inside the second electromagnetic hydraulic switching valve 15, there is provided a drive device 10 having a simple structure and an inexpensive structure without separately providing a diversion valve as in the conventional case. You can <Second Embodiment> Next, a second embodiment of the present invention will be described.

FIG. 2 is a hydraulic system diagram showing the construction of a hydraulic actuator drive system according to a second embodiment of the present invention.

The present embodiment is different from the first embodiment in that in the first embodiment, the pressure of the rod side port 41 is always introduced during the operation of the second cylinder 12 so that the pressure from the first cylinder 11 is removed. Although the return oil is configured to be diverted and the high pressure priority type shuttle valve 48 is provided for that purpose (see FIG. 1), in the drive device 50 according to the present embodiment,
Instead, by providing the pilot pressure selection mechanism 51, the return oil from the first cylinder 11 can be diverted only when required. Since the other configurations are the same as those in the first embodiment, the same components as those shown in FIG. 1 are denoted by the same reference numerals in FIG. 2, and the description thereof will be omitted.

Referring to FIG. 2, pilot pressure selection mechanism 5
1 will be described.

The pilot pressure selection mechanism 51 includes a solenoid valve 5
Switching valve unit (switching valve means) 54 provided with 2, 53
And first to fourth pilot lines 55 to 58 connected thereto.

The electromagnetic valves 52 and 53 are electromagnetic directional control valves having the same structure, and guide the pressure to be introduced in a required direction described later. Therefore, these solenoid valves 52 and 53 do not switch the direction of the large flow rate of hydraulic oil, but can be small and inexpensive.

The solenoid valve 52 has a first port 59 (first input port), a second port 60 (second input port), and a third port 61, and the first port 59 or the third port 61 is switched by switching the valve. Either one of the pressures introduced into the second port 60 is guided to the third port 61. The solenoid valve 53 has a first port 62 (third input port), a second port 63, and a third port 64 (output port), and is introduced into the first port 62 or the second port 63 by switching the valve. Either one of the applied pressures is introduced to the third port 64. In this embodiment, the solenoid valves 52 and 53 are configured as one switching valve unit 54, and any one of the pressures introduced from the first to third pilot lines 55 to 57 is selected. , And is guided to the pilot port 21 of the sequence valve 20 via the fourth pilot line 58.

Here, the first pilot line 55 controls the pressure of the rod side port 41 of the second cylinder 12 by the solenoid valve 5
2 to the first port 59. Second pilot line 56
Controls the primary pressure of the sequence valve 20 to the second side of the solenoid valve 52.
Take to port 60. In addition, the third pilot line 57
Guides the pressure of the secondary side port of the pressure reducing valve 44 to the first port 62 of the solenoid valve 53. The third port 6 of the solenoid valve 52
1 and the second port 63 of the solenoid valve 53 are hydraulically connected.

According to the present embodiment, the driving device 50 operates as follows.

By operating the hydraulic pump 16, hydraulic oil of a predetermined pressure (hydraulic pressure) is supplied from the hydraulic power source 13. This hydraulic oil is used in the first and second hydraulic oils as shown in FIG.
When the electromagnetic hydraulic switching valves 14 and 15 are in the A mode, they are returned to the oil tank 17 via the main hydraulic line 18. At this time, the pressure reducing valve 44 of the spool switching pressure supply unit 19
Secondary pressure is introduced to the sequence valve 20 via the third pilot line 57 and the switching valve unit 54. Therefore, in the main hydraulic pressure line 18, almost the same pressure as the secondary pressure of the pressure reducing valve 44 is always generated, so that the pilot pressure supply line 2 is based on the pressure generated in the main hydraulic pressure line 18.
A predetermined pressure is generated at 3, and this pressure can move the internal spools of the first and second electromagnetic hydraulic switching valves 14 and 15. That is, the first and second electromagnetic hydraulic switching valves 14 and 15 are in the neutral state (A mode).
Even if the first and second electromagnetic hydraulic switching valves 14, 15
You can change the direction of the hydraulic oil by operating.

Next, when the first electromagnetic hydraulic switching valve 14 is switched to the C mode and the second electromagnetic hydraulic switching valve 15 is switched to the B mode, the return oil of the first cylinder 11 is returned to the second cylinder 12. It is fed to the rod side port 41.

(1) When the solenoid valves 52, 53 are in the state shown in FIG. 2 In this case, the secondary pressure of the pressure reducing valve 44 is passed through the third pilot line 57, the switching valve unit 54 and the fourth pilot line 58. It is in a state of being guided to the sequence valve 20.

In this state, as is clear from FIG.
The pressures of the first branch channel 39 and the second branch channel 40 cannot be equalized, and the second branch channel 40 side has a low pressure. For this reason, the return oil from the first cylinder 11 cannot be flow-divided by the split passages 39 and 40, and a large amount of return oil is sent to the main hydraulic line 18 side. As a result, especially the second
The cylinder 12 can be stroked at a low speed.

Even in this case, as described above, the main hydraulic line 18 always has a pressure substantially similar to the secondary pressure of the pressure reducing valve 44. Therefore, the first and second pressures are generated based on the pressure. The electromagnetic hydraulic switching valves 14 and 15 can be operated.

(2) When only the solenoid valve 53 is switched from the state shown in FIG. 2 In this case, the pressure of the rod side port 41 of the second cylinder 12 via the first pilot line 55 is the same as that of the solenoid valve 52. The pressure is introduced to the 1st port 59, and its pressure is introduced to the sequence valve 20 via the 4th pilot line 58 through the 2nd port 63 and the 3rd port 64 of the solenoid valve 53.

In this state, as in the first embodiment, the return oil from the first cylinder 11 is returned to the second cylinder 1 by the branch passages 39, 40 and the throttles 46, 47.
Regardless of the magnitude of the load of No. 2, the flow is always divided at a constant ratio, and in the first branch flow passage 39, of the total amount of return oil, the first cylinder 1 with respect to the rod-side effective area of the second cylinder 12
Only the amount multiplied by the ratio of the effective area on the head side of 1 will be sent. That is, the same amount of return oil as the amount of hydraulic oil sent to the rod side of the first cylinder 11 is sent to the rod side of the second cylinder. As a result, the first serially arranged
Also, the operation (stroke) of the second cylinders 11 and 12 can be synchronized.

(3) Solenoid valves 52, 5 from the state shown in FIG.
In this case, the primary side pressure of the sequence valve 20 is changed to the second port 60 of the solenoid valve 52 via the second pilot line 56.
And its pressure passes through the second port 63 and the third port 64 of the solenoid valve 53 and passes through the fourth pilot line 58.
It is in the state of being guided to the sequence valve 20 via.

In this state, the primary side pressure of the sequence valve 20 remains as it is in the pilot port 21 of the sequence valve 20.
Be led to. Here, due to the structure of the sequence valve 20, the pressure to be introduced is a value obtained by adding the spring force of the pressure adjusting spring built in the sequence valve 20 to the primary side pressure of the sequence valve 20. The valve 20 will be fully closed.

Therefore, the entire amount of the return oil from the first cylinder 11 passes through the first diversion valve 39 and the second cylinder 1
It is fed to the second rod-side port 41, and as a result, the stroke of the second cylinder 12 can be increased.

As described above, in the present embodiment, the pilot pressure selection mechanism 51 selects one of the secondary pressure of the pressure reducing valve 44, the pressure of the rod side port 41 of the second cylinder 12 and the primary side pressure of the sequence valve 20. Since the pressure can be arbitrarily selected and guided to the sequence valve 20, when it is desired to synchronize the strokes of the first and second cylinders 11 and 12 connected in series, it is possible to do so, and the stroke of the second cylinder 12 is synchronized. If you want to go faster or slower without doing it, you can do so.

Moreover, in the present embodiment, as described above, it is the pilot pressure, not the hydraulic oil, that is switched by the solenoid valves 52, 53, so the structure of the pilot pressure selection mechanism 51 can be made compact. Therefore, it is not necessary to secure a wide space for disposing the pilot pressure selection mechanism 51 and a piping space.

In addition, in the present embodiment, the pilot pressure selection mechanism 51 includes the switching valve unit 54 having the solenoid valves 52 and 53 and the pilot lines 55 connected thereto.
Since it is constituted by 58 to 58, there is an advantage that the structure is simple and inexpensive. <Modification> Next, a modification of the second embodiment will be described.

FIG. 3 is a hydraulic system diagram showing the configuration of a hydraulic actuator drive device according to a modification of the second embodiment of the present invention.

The difference of this modification from the second embodiment is that in the second embodiment (see FIG. 2), the pilot pressure selection mechanism 51 includes two electromagnetic valves 52 and 53, and the pressure reducing valve 4
The secondary pressure of 4, the pressure of the rod-side port 41 of the second cylinder 12 or the primary pressure of the sequence valve 20 is selected and guided to the sequence valve 20, whereas In this modified example, as shown in FIG. 3, the pilot pressure selection mechanism 65 includes a single solenoid valve 66, and the secondary pressure of the pressure reducing valve 44 or the second cylinder 12 is used.
This is that any one of the pressures of the rod side ports 41 can be arbitrarily selected and guided to the sequence valve 20.

In this case, the pressure of the rod side port 41 of the second cylinder 12 is guided to the first port 69 of the solenoid valve 66 by the first pilot line 67, and the secondary pressure of the pressure reducing valve 44 is the second pilot line. 68 leads to the second port 70 of the solenoid valve 66. Then, one of these is guided to the third port 71 of the solenoid valve 66, and its pressure is supplied to the sequence valve 2 by the third pilot line 72.
Lead to zero. In this modification, the drive device 50 operates as follows by switching the solenoid valve 66.

First, as shown in the state shown in FIG.
When the secondary pressure of No. 2 is introduced to the sequence valve 20, as is apparent from FIG. 3, the pressures of the first branch channel 39 and the second branch channel 40 cannot be made equal, and the second branch channel 40 The pressure becomes low on the side. For this reason, by the bifurcating channels 39 and 40,
The return oil from the cylinder 11 cannot be split in a constant ratio, and a large amount of the return oil is sent to the main hydraulic line 18 side.
As a result, the second cylinder 12 can be stroked at a low speed.

Moreover, in this case, as described above, the main hydraulic line 18 always generates a pressure substantially similar to the secondary pressure of the pressure reducing valve 44, and therefore the first and second pressures are generated based on the pressure. The electromagnetic hydraulic switching valves 14 and 15 can be operated.

Next, when the solenoid valve 66 is switched from the state shown in FIG. 3 to guide the pressure of the rod side port 41 of the second cylinder 12 to the sequence valve 20, the first cylinder 11 is operated as described above. It is possible to divide the return oil from the constant ratio and to synchronize the strokes of the first and second cylinders 11 and 12.

As described above, also in this modification, when it is desired to synchronize the strokes of the first and second cylinders 11 and 12 connected in series, the solenoid valve 6 is operated at a desired timing.
Tuning can be performed by switching 6.

[0092]

As described above, according to the present invention, the pressure oil supplied from the predetermined path is diverted by the switching valve to a predetermined diverting ratio, and the diverted pressure oil is fed to the hydraulic actuator. it can. Therefore, when adjusting the operating speed of the hydraulic actuator, it is not necessary to separately provide a flow dividing valve as in the conventional case. As a result, the hydraulic actuator drive device capable of adjusting the operating speed can be made simple and inexpensive.

In particular, when driving the first and second hydraulic actuators arranged in series, the following unique effects are obtained. In other words, regarding the operation of the two hydraulic actuators, since the return oil from the first hydraulic actuator is split in the second electromagnetic hydraulic switching valve for feeding to the second hydraulic actuator, a constant ratio shunting is performed. It is possible to configure an inexpensive hydraulic actuator drive device with a simple structure without providing a flow dividing valve.

Further, since a method of introducing a predetermined pressure from the drive system hydraulic system to the pressure control valve in order to perform the constant-ratio diversion is adopted, when the pressure is not introduced using the pilot pressure selection mechanism. Does not perform the above diversion,
It is also possible to operate the second hydraulic actuator at a particularly high speed or a low speed.

Moreover, since the pilot pressure selection mechanism guides only the pilot pressure, a means for controlling it (for example, a switching valve) can be small and inexpensive, and the installation and piping space can be reduced. You can avoid problems and higher costs.

[Brief description of drawings]

FIG. 1 is a hydraulic system diagram showing a configuration of a hydraulic actuator drive device according to a first embodiment of the present invention.

FIG. 2 is a hydraulic system diagram showing a configuration of a hydraulic actuator drive device according to a second embodiment of the present invention.

FIG. 3 is a hydraulic system diagram showing a configuration of a hydraulic actuator drive device according to a modification of the second embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a conventional hydraulic actuator drive device as a hydraulic system diagram.

[Explanation of symbols]

10 Drive 11 1st cylinder 12 Second cylinder 13 Hydraulic power source 14 First electromagnetic hydraulic switching valve 15 Second electromagnetic hydraulic switching valve 16 hydraulic pump 17 oil tank 18 Main hydraulic line 20 Sequence valve 21 Pilot port 39 First branch channel 40 Second branch channel 41 Rod side port 45 pilot line 46 aperture 47 aperture 48 High pressure priority shuttle valve 49 connection line 50 drive 51 Pilot pressure selection mechanism 52 Solenoid valve 53 Solenoid valve 54 Switching valve unit 55 First pilot line 56 Second pilot line 57 Third pilot line 58 4th pilot line 59 1st port 60 Second port 62 First port 65 Pilot pressure selection mechanism 64 3rd port 66 Solenoid valve 67 First pilot line 68 Second pilot line 69 1st port 70 Second port 71 3rd port 72 Third pilot line

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 3H089 AA60 AA73 BB19 CC01 CC11                       DA02 DB03 DB37 DB45 DB47                       DB48 DB49 DB55 GG02 JJ01

Claims (5)

[Claims] 1. A hydraulic actuator drive device for driving a hydraulic actuator by a hydraulic pressure source that sucks up hydraulic oil from an oil tank to supply pressure oil, the first mode or supply supplying the supplied pressure oil to the oil tank side. Second for feeding the generated pressure oil to the hydraulic actuator
It has a switching valve that can switch to a mode and a pilot port that guides the external pilot pressure.
A pressure control valve for generating a predetermined pressure on the downstream side of the switching valve by using an external pilot pressure, wherein the switching valve transfers the pressure oil to the hydraulic actuator side in a state of switching to the second mode. A first branch flow passage and a second branch flow passage for dividing the flow into the oil tank side and the oil tank side respectively. The first branch flow passage and the second branch flow passage each have a throttle having a predetermined throttle area, A hydraulic actuator driving device comprising a pilot line for guiding the pressure of the side port to the pilot port of the pressure control valve. 2. A hydraulic actuator drive device for operating a first hydraulic actuator and a second hydraulic actuator that are arranged in series, the hydraulic oil being sucked up from an oil tank and supplied with a predetermined hydraulic source pressure. A first mode in which a hydraulic pressure source having a main hydraulic pressure line connecting a pump and a hydraulic pump to an oil tank and a hydraulic pressure source which is arranged in series with the main hydraulic pressure line and which supplies hydraulic fluid supplied from the hydraulic pressure source to the main hydraulic pressure line, or A first electromagnetic hydraulic switching valve that can switch to a second mode in which hydraulic oil supplied from a hydraulic source is sent to a first hydraulic actuator, and that uses the hydraulic source pressure for the switching; The first hydraulic actuator is arranged in series with the hydraulic pressure switching valve and is arranged in series with the main hydraulic pressure line, and supplies return oil from the first hydraulic actuator to the main hydraulic pressure line. A second electromagnetic hydraulic switching valve that can be switched to a first mode or a second mode in which the return oil from the first hydraulic actuator is fed to the second hydraulic actuator, and that uses the hydraulic source pressure for the switching. And a pressure control valve which is arranged in series with the main hydraulic line and has a pilot port for generating a predetermined hydraulic source pressure in the main hydraulic line by utilizing an external pilot pressure. The valve controls the return oil to the second mode in the state where it is switched to the second mode.
A first branch flow passage and a second branch flow passage are formed to divide into a supply side port to the hydraulic actuator and a main hydraulic line, respectively, and the first branch flow passage and the second branch flow passage each have a throttle having a predetermined throttle area. A hydraulic actuator drive device is further provided with a pilot line for guiding the pressure of the supply side port of the second hydraulic actuator to the pilot port of the pressure control valve. 3. A hydraulic actuator drive device for operating a first hydraulic actuator and a second hydraulic actuator, which are arranged in series, wherein the hydraulic oil is sucked up from an oil tank and supplied with a predetermined hydraulic source pressure. A first mode in which a hydraulic pressure source having a main hydraulic pressure line connecting a pump and a hydraulic pump to an oil tank and a hydraulic pressure source which is arranged in series with the main hydraulic pressure line and which supplies hydraulic fluid supplied from the hydraulic pressure source to the main hydraulic pressure line, or A first electromagnetic hydraulic switching valve that can switch to a second mode in which hydraulic oil supplied from a hydraulic source is sent to a first hydraulic actuator, and that uses the hydraulic source pressure for the switching; The first hydraulic actuator is arranged in series with the hydraulic pressure switching valve and is arranged in series with the main hydraulic pressure line, and supplies return oil from the first hydraulic actuator to the main hydraulic pressure line. A second electromagnetic hydraulic switching valve that can be switched to a first mode or a second mode in which the return oil from the first hydraulic actuator is fed to the second hydraulic actuator, and that uses the hydraulic source pressure for the switching. And a pressure control valve which is arranged in series with the main hydraulic line and has a pilot port for generating a predetermined hydraulic source pressure in the main hydraulic line by utilizing an external pilot pressure. The valve controls the return oil to the second mode in the state where it is switched to the second mode.
A first branch flow passage and a second branch flow passage are formed to divide into a supply side port to the hydraulic actuator and a main hydraulic line, respectively, and the first branch flow passage and the second branch flow passage each have a throttle having a predetermined throttle area. The pilot pressure introduced to the pilot port of the pressure control valve by selecting one of the pressure of the supply port of the second hydraulic actuator, the primary pressure of the pressure control valve, and the hydraulic source pressure. A hydraulic actuator drive device comprising a selection mechanism. 4. The hydraulic actuator drive system according to claim 3, wherein the pilot pressure selection mechanism includes first to third input ports and an output port connected to any one of these input ports. Valve means, a first pilot line for guiding the pressure of the supply side port of the second hydraulic actuator to the first input port of the switching valve means, and the primary side pressure of the pressure control valve for the second side of the switching valve means. The second pilot line leading to the input port and the hydraulic source pressure of the main hydraulic line are provided to the third of the switching valve means.
A hydraulic actuator drive device, comprising: a third pilot line for guiding the input port; and a fourth pilot line for guiding the pressure of the output port of the switching valve means to the pilot port of the pressure control valve. 5. The hydraulic actuator drive device according to claim 3, wherein the pilot pressure selection mechanism includes first and second input ports and an output port connected to any one of these input ports. A switching valve, a first pilot line for guiding the pressure on the supply side port of the two hydraulic actuators to a first input port of the switching valve, and a hydraulic source pressure for the main hydraulic line to a second input port of the switching valve. A hydraulic actuator drive device comprising: a second pilot line; and a third pilot line for guiding the pressure of the output port of the switching valve to the pilot port of the pressure control valve.