JPH03249411A - Hydraulic driving device - Google Patents

Abstract

PURPOSE:To use the same directional control valve regardless of whether for a domestic or special specification by providing a directional control valve comprising a proportional sheet valve that contains a relief valve, a pilot control part that controls the opening thereof, and a line that directly links the directional control valve and a tank. CONSTITUTION:A pilot control part 20 that drives a directional control valve 30 provided with a relief valve 18 and a proportional sheet valve 17, a check valve 16, and the proportional sheet valve 17, is provided in a main body block 32. The proportional sheet valve 17 is provided with a sheet part 40 which opens by the difference in pressure between a back pressure chamber 38 and a channel 36, while the pilot control part 20 is composed of a spool 23 as well as of springs 24, 25, and is communicated to the back pressure chamber 38 and to channel 36 through pilot lines 21, 22. The spring force of a spring 25 is adjusted by a plug 26 of the pilot control part 20, and the channel 36 is directly linked to a tank 12 by a line 14. The same directional control valve 4 can thus be used for a device of domestic specification and for a device of special specification, and a smallness is achieved, while malfunction can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hydraulic drive system, and more particularly to a hydraulic drive system equipped with a valve device that prevents falling due to loads in the direction of gravity.

[Conventional technology]

FIG. 2 is a circuit diagram showing the configuration of a conventional hydraulic drive device. As shown in the figure, a directional switching valve 4 is connected to a hydraulic pump 1 as a hydraulic power source, and this directional switching valve 4 is connected to a pipe line 28. It is connected to a boat 3b of a hydraulic cylinder 2, which is a hydraulic actuator, through a pipe line 31, and to a tank 12 through a pipe line 31.

A valve device 5 is connected between the hydraulic cylinder 2 and the directional control valve 4, and this valve device 5 includes a check valve 8.9 and a relief valve 8'.
, and a switching valve 10 having a spring 11.

One end of a relief valve 8' is connected to the boat 3a of the hydraulic cylinder 2, and the other end of the relief valve 8' is connected to a tank 12 via a conduit 14.

Further, one end side of the check valve 8 is connected to the boat 3a of the hydraulic cylinder 2, and the other end side of the check valve 8 is connected to the main pipe line 1.
3 to a directional control valve 4.

Similarly, one end of the check valve 9 is connected to the boat 3a of the hydraulic cylinder 2, the other end of the check valve 9 is connected to one end of the switching valve 10, and the other end of the switching valve 10 is connected to the main pipe. It is connected to the directional control valve 4 via 13.

The configuration is such that operating pressure is applied to the switching valve 10 by switching the directional switching valve 4 to the right position in FIG.

Next, the operation of the conventional hydraulic drive device having such a configuration will be explained.

When the directional switching valve 4 is switched to the neutral position as shown in FIG. In this state, the hydraulic cylinder 2 is receiving a force in the direction shown by the arrow 6 in the figure due to the load in the direction of gravity, but the valve device 5
The return oil from the boat 3a to the hydraulic cylinder 2 is blocked by the check valve 8.9.

Therefore, the return oil from the boat 3a of the hydraulic cylinder 2 is not discharged, and the hydraulic cylinder 2 is held stationary.

When the directional control valve 4 is switched to the left position in FIG.
Pressure oil from the hydraulic pump 1 passes from the directional control valve 4 through the main pipe 13, pushes open the check valve 8, and is supplied to the hydraulic cylinder 2 from the boat 3a. At this time, the return oil from the boat 3b of the hydraulic cylinder 2 is transferred to the pipe 28, the directional control valve 4, and the pipe 3.
1 to the tank 12.

Therefore, when the directional control valve 4 is switched to the left position in FIG. 2, the hydraulic cylinder 2 moves in the direction of the arrow 7 in the same figure.

In this way, after the hydraulic cylinder 2 has moved in the direction of the arrow 7 in FIG. 2, when the device is stopped and the directional control valve 4 is switched to the neutral position, the hydraulic cylinder 2 is held stationary as described above. Ru.

At this time, due to gravity, the hydraulic cylinder 2 moves to the arrow 6 in Fig. 2.
A force is applied in the direction, but for some reason boat 3
When the pressure oil in section a reaches an overload pressure that exceeds a preset allowable value, the relief valve 8' opens and the overload pressure is released through the pipe line 14.

Further, even if the directional switching valve 4 fails and cannot be switched to the right position in FIG. 2, and the hydraulic cylinder 2 stops in the raised state, the switching valve 10 cannot be switched to the left position.
Check valve 9 is never opened. At this time, the directional control valve 4 and the check valve 8 are also in the cutoff state, and the pressure oil is in the pipe line 31.
There is no leakage into tank 12 through. In this case as well, if an overload pressure occurs in the pressure oil at the port 3a, the relief valve 8' opens to release the overload pressure, thereby preventing the occurrence of a dangerous situation.

As described above, in the conventional hydraulic drive device, the hydraulic cylinder 2 is moved upward or downward by the switching operation of the directional control valve 4, and when the device is stopped, the hydraulic cylinder 2 is safely held in that position, and the gravity It will not fall due to the load (direction downward).

Further, if an excessive load pressure is generated while the hydraulic cylinder 2 is in a held state, the relief valve 8' opens and the excessive load pressure is released, thereby preventing the occurrence of a dangerous situation.

[Problem to be solved by the invention]

The conventional hydraulic drive device shown in FIG. 2 mentioned above is a special specification, for example, European specification, which requires particularly high safety, and the device used in Japan has a structure in which the valve device 5 is removed. Usually used.

In this domestic specification device, the directional control valve 4 is provided with a throttle function, and the operating speed of the hydraulic cylinder 2 is configured to depend on the operating stroke of the directional control valve 4.

When the valve device 5 shown in Fig. 2 is installed in this domestic specification device,
The switching valve 10 has a throttling function, and the return oil from the boat 3a passes through the switching valve 10 and the directional switching valve 4 to the tank 12.
As a result, the device becomes a double throttle type device, and the operating speed of the hydraulic cylinder 2 is significantly reduced.

Therefore, in order to obtain a special specification (European specification) device from a domestic specification device, the domestic specification directional control valve 4 is replaced with a directional control valve 4 that has almost no throttling function, and the valve device 5 is added. The device was changed to one that achieves the desired operating speed of the hydraulic cylinder 2.

Therefore, when manufacturing a hydraulic drive device that is subject to this type of load in the direction of gravity, it is necessary to manufacture two types of directional valves: a domestic specification directional valve and a special specification directional valve.
Problems arise in terms of manufacturing costs.

In addition, there is a risk of incorrect selection of the directional control valve. If a domestic specification directional control valve is incorrectly selected as a special specification, the device will become a double throttling configuration as described above, and the operating speed of the hydraulic cylinder will significantly decrease. Resulting in. On the other hand, if a special specification directional control valve is incorrectly selected as a domestic specification, there is a risk that the hydraulic cylinder will operate excessively due to the flow of pressure oil, resulting in a fall accident.

The present invention has been made in view of the current state of conventional hydraulic drive systems as described above, and its purpose is to provide a hydraulic drive system that can be provided with the same directional control valve regardless of whether it is a domestic specification or a special specification. be.

[Means to solve the problem]

To achieve the above object, the present invention includes a hydraulic source, a hydraulic actuator driven by pressure oil supplied from the hydraulic source, and a direction for controlling the flow of the pressure oil supplied from the hydraulic source to the hydraulic actuator. A hydraulic drive device comprising a switching valve, a check valve that prevents the hydraulic actuator from operating due to a load in the direction of gravity, and a relief valve that is interposed between the hydraulic actuator and a tank to release excessive load pressure. , a switching valve consisting of a proportional seat valve incorporating the relief valve; a pilot control unit that controls the opening degree of the switching valve according to its throttle amount; and connecting the switching valve and the tank via the directional switching valve. The structure has a conduit that communicates without any need for communication.

[Effect]

In the present invention, the flow of pressure oil supplied from a hydraulic source to a hydraulic actuator is controlled by a directional control valve.

When the directional valve is switched to the neutral position, no pressure oil from the hydraulic source is supplied to the hydraulic actuator. In this state, the proportional seat valve portion of the switching valve is closed and the check valve is also closed, so return oil from the hydraulic actuator is not discharged into the tank.

In this way, when the directional valve is switched to the neutral position,
The hydraulic actuator remains stationary.

When the directional valve is switched to the first position, pressure oil from the hydraulic source passes through the directional valve, opens the check valve, and is supplied to the hydraulic actuator. This pressure oil causes the hydraulic actuator to move in a direction (upward) against gravity, and the return oil from the hydraulic actuator is discharged into the tank via the directional control valve.

When the directional switching valve is switched to the second position, operating pressure is applied to the pilot control section, the throttle of the pilot control section opens, and the degree of opening of the proportional seat valve portion of the switching valve is controlled by the amount of the throttle.

In this case, the pressure oil from the hydraulic source moves the hydraulic actuator,
The return oil from the hydraulic actuator is discharged into the tank from the switching valve whose proportional seat valve part is opened by the pilot control unit through the pipe line without going through the directional switching valve. Ru.

Additionally, if an excessive load pressure occurs in the pressure oil inside the hydraulic actuator while the hydraulic actuator is held stationary,
The relief valve opens and the overload pressure is released to the tank, preventing an abnormal situation from occurring.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Here, FIG. 1 is a circuit diagram including a cross-sectional part showing the configuration of an embodiment.
The directional control valve 4 is connected to the boat 3b of the hydraulic cylinder 2, which is a hydraulic actuator, through a conduit 28. The directional control valve 4 is also connected to the flow path 37 of the check valve 16 of the valve device 15 through the main line 13, and further connected to the tank 12 through the line 31.

The boat 3a of the hydraulic cylinder 2 is connected to the flow path 35 of the switching valve 30 of the valve device 15 by a conduit 29,
The flow path 36 of the switching valve 30 is connected to the tank 1 by the pipe line 14.
Connected to 2.

The valve device 15 includes a switching valve 3 which is provided with a relief valve 18 and a proportional seat valve 17 in parallel to each other in a main body block 32.
0, a check valve 16, and a pilot control section 20 that controls the driving of the proportional seat valve 17.

The proportional seat valve 17 of the switching valve 30 connects the back pressure chamber 38 and the flow path 3.
A relief valve 18 is formed integrally with the proportional seat valve 17. The relief valve 18 includes a spring 41 and a valve body 42 biased by the spring force of the spring 41. Note that the valve body 42 is operated by pressure oil introduced through the slit 19.

Therefore, in the relief valve 18, when the pressure of the pressure oil in the flow path 35 communicating with the slit 19 becomes an overload pressure greater than the force of the spring 41, the valve body 42 moves against the spring 41. Excessive load pressure is released from the pipe line 14 to the tank 12.

The check valve 16 includes a valve body 44 that is closed by the spring force of a spring 43, and the pressure of the pressure oil in the flow path 37 and the spring 43
When the spring force becomes larger than the spring force, the seat portion 45 opens and the flow path 37 communicates with the flow path 35.

The pilot control unit 20 is provided with a spool 23 that is movable in the axial direction, and this spool 23 is supported by springs 24, 25.
It is shifted to the left in Fig. 1 by. The pilot control unit 20 also includes a back pressure chamber 38 of the switching valve 30 and a flow path 3.
Pilot lines 21, 22 are connected to the 6 and 6, respectively.

Operation pressure is applied to the pilot control unit 20 from the directional switching valve 4 when the directional switching valve 4 is switched to the right position in FIG.

When no operating pressure is applied, the spool 23 is biased to the left, as described above, and the pilot lines 21, 22 are isolated from each other.

When operating pressure is applied to the pilot control section 20, the spool 23 moves against the spring 24.25, and the pilot conduits 21.22 are brought into communication with each other.

A plug 26 is attached to one end of this pilot control unit 20, and the tightening state of this plug 26 is adjusted so that the spring force of the spring 25 can be adjusted. There is.

Next, the operation of the embodiment having such a configuration will be explained.

When the directional control valve 4 is switched to the neutral position as shown in FIG. 1, pressure oil from the hydraulic pump 1 is not supplied to the hydraulic cylinder 2. At this time, a force is acting on the hydraulic cylinder 2 in the direction of gravity, but the seat portion 40 of the proportional seat valve 17 portion of the switching valve 30 is closed, and the seat portion 45 of the check valve 16 is also closed. Return oil from the boat 3a does not flow into the tank 12.

Therefore, in a state where the directional control valve 4 is switched to the neutral position in this manner, the hydraulic cylinder 2 maintains a stationary state.

When the directional control valve 4 is switched to the first position, which is the left position in FIG. , moving the valve body 44 against the spring force of the spring 43;
Open the seat section 45.

Therefore, the pressure oil passes from the flow path 37 to the flow path 35 and passes through the pipe line 2.
9 to the boat 3a of the hydraulic cylinder 2.

At this time, the return oil from the boat 3b of the hydraulic cylinder 2 is
It passes through the line 28 and is led to the tank 12 via the directional control valve 4 and the line 31.

Therefore, when the directional control valve 4 is switched to the left position in FIG. 1, the hydraulic cylinder 2 resists gravity as shown by the arrow 7 in the figure by the pressure oil supplied to the boat 3a from the hydraulic pump 1. move in the direction (upward).

As mentioned above, when the directional control valve 4 is in a stationary state where it is kept in the neutral position, for some reason, the pressure oil in the boat 3a becomes
When an overload pressure exceeding a preset allowable value occurs, the pressure oil reaching the valve body 42 through the slit 19 moves the valve body 42 against the spring force of the spring 41.

For this reason, the pressure oil that has become overloaded is removed from the pipe 29.
It is guided to the tank 12 via the flow path 35, slit 19, flow path 36, and pipe line 14, and the overload pressure is released, thereby preventing the occurrence of a dangerous situation due to the overload pressure.

When the directional control valve 4 is switched to the second position, which is the right position in FIG. Ru.

At the same time, by switching the directional valve 4, operating pressure is applied to the pilot control section 20 of the valve device 15, and the spring 24.
Since the spool 23 moves against the spring force of the spool 25, the pilot lines 21 and 22, which had been cut off, are brought into communication.

Therefore, the pressure oil in the pilot pipe 21 flows out into the pilot pipe 22, the pressure in the back pressure chamber 38 decreases, the proportional seat valve 17 of the switching valve 30 moves, and the seat part 40 becomes open. Become. For this reason, the return oil from the boat 3a of the hydraulic cylinder 2 passes through the flow path 35 from the pipe 29, and is controlled by the proportional seat valve 17 from the seat portion 40, passes through the flow path 36 and the pipe 14, and enters the tank 12. be guided.

Therefore, when the directional control valve 4 is switched to the right position in FIG. 1, the hydraulic cylinder 2 is moved in the direction of gravity as shown by the arrow 6 in the figure by the pressure oil supplied to the boat 3b from the hydraulic pump 1. Moving.

In this way, according to the embodiment, the hydraulic cylinder 2, which is loaded in the direction of gravity, can be raised, lowered, or safely kept stationary by switching the directional control valve 4. Furthermore, if an overload pressure exceeding a predetermined allowable value occurs in the boat 3a portion of the hydraulic cylinder 2, the relief valve 18 opens and the overload pressure is released, thereby preventing abnormal situations caused by the overload pressure. Ru.

The tightening of the plug 26 can be adjusted to suit the operating characteristics of the proportional seat valve 17 by changing the state and the spring force of the spring 25.

Further, if necessary, the hydraulic cylinder 2 can be moved with the switching valve 30 in the open state by moving the spool 23 using a jig, for example, instead of switching the directional switching valve 4.

When the hydraulic cylinder 2 is operated in the direction of gravity, the return oil from the hydraulic cylinder 2 can be guided to the tank 12 without passing through the directional control valve 4. It becomes possible to use valve 4. Therefore, manufacturing costs are reduced and the problem of incorrect selection of the directional valve does not occur.

Further, the valve device 15 has a structure in which a switching valve 3° including a pilot control section 20, a check valve 16, a proportional seat valve 17, and a relief valve 18 is housed in parallel in the main body 32, so that the entire valve device 15 is compact.

〔Effect of the invention〕

In the present invention, when operating a hydraulic actuator that is subjected to a load in the direction of gravity, when moving in the direction of gravity, pressure oil is guided from the conduit to the tank without passing through the directional control valve. Therefore, when manufacturing domestic specification equipment and special specification equipment, there is no possibility of selecting the directional control valve incorrectly as in the past. This prevents the load from falling.

Further, since the proportional seat valve structurally includes a conventional relief valve and a pilot type check valve, the overall structure can be made compact.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram including a cross section showing an embodiment of the hydraulic drive device of the present invention, and FIG. 2 is a circuit diagram showing a conventional hydraulic drive device. 1... Hydraulic pump, 2... Hydraulic cylinder, 3a, 3b... Boat, 4... Directional switching valve, 12... Tank , 13...
Main pipeline, 14.28.31...Pipeline, 15...
... Valve device, 16... Check valve, 17.
...Proportional seat valve, 18...Relief valve, 19...Slit, 20...Pilot control section, 21.22...Pilot pipe road,
23...Spool, 24.25...Spring, 26...Plug, 30...Switching valve, 32...Body, 35. 36.37...
・Flow path, 38... Back pressure chamber, 40... Seat part, 41... Spring, 42... Valve body, 43...・Spring, 44... Valve body, 45
・・・・・・Seat part. Figure 5 Dezun 1

Claims (1)

[Claims] (1) A hydraulic source, a hydraulic actuator driven by pressure oil supplied from the hydraulic source, a directional switching valve that controls the flow of the pressure oil supplied from the hydraulic source to the hydraulic actuator, and a direction of gravity. A hydraulic drive device comprising a check valve that prevents the hydraulic actuator from operating due to a load, and a relief valve interposed between the hydraulic actuator and a tank to release excessive load pressure, the relief valve being built-in. A switching valve consisting of a proportional seat valve, a pilot control unit that controls the opening degree of the switching valve according to its throttle amount, and the switching valve and the tank are communicated without going through the directional switching valve. A hydraulic drive device characterized by having a conduit.