JP2002349502A - Hydraulic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic device capable of prevent the occurrence of an energy loss. SOLUTION: Any object to be transported is moved while the supply and exhaust of a working oil to/from the working chambers 54 and 56 of hydraulic cylinders 50 and 52 is changed over by a control valve 60, and a load due to the object is applied to the cylinders 50 and 52 when the supply and exhaust is stopped. In a supply/exhaust passage 58 leading from the working chambers 54 and 56 to the control valve 60, a pair of externally operated check valves 1 and 2 are installed directed oppositely so that a flow in one direction can be restricted and also the restriction can be disengaged. The externally operated check valves 1 and 2 disengage the restriction of the flow in one direction in conformity to a fed energize signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic device for supplying and discharging hydraulic oil to and from a working chamber of a hydraulic cylinder to which a load is applied by a transported body when supply and discharge are stopped.

[0002]

2. Description of the Related Art Conventionally, a load of a transferred body is applied to a hydraulic cylinder used for a lift cylinder for raising and lowering a cargo handling attachment such as a fork of a forklift when supply and discharge of hydraulic oil to and from a working chamber are stopped. A hydraulic device that supplies and discharges hydraulic oil to and from such a hydraulic cylinder, as shown in FIG.
A supply / discharge flow path 58 connected to the working chambers 54, 56 of the pair of hydraulic cylinders 50, 52 is provided.
Connected to 0.

By switching the control valve 60, hydraulic oil is supplied from the hydraulic pump 62 to the working chambers 54, 56 via the supply / discharge passage 58, and the hydraulic tank 64 via the supply / discharge passage 58. Is returned to the hydraulic oil. The supply / discharge channel 58 is provided with a flow rate control valve 66 for controlling a descending speed.

Further, an externally operated check valve 70 is interposed in the supply / discharge passage 58. Externally operated check valve 7
Numeral 0 functions as a check valve for restricting the outflow of hydraulic oil from the working chambers 54 and 56, and can release the restriction when an excitation signal is input from the outside. In addition, the hydraulic cylinders 50, 5
The fuse valves 72 and 74 are interposed every two.

As described above, the externally operated check valve 70 is interposed in the supply / discharge passage 58 so that when the supply / discharge of hydraulic oil through the supply / discharge passage 58 is stopped, the action chamber 54, 5
Since the outflow of hydraulic oil from 6 is regulated by the externally operated check valve 70, it is possible to prevent the transported object from falling by its own weight. When the transported body is lowered, the operating oil can be discharged through the supply / discharge flow path 58 by inputting an excitation signal to the externally operated check valve 70.

As shown in FIG. 3, another hydraulic actuator 80 may be connected to the control valve 60. Depending on the connection or structure, the switching operation of the control valve 60 may cause pressure interference. is there. In this case, FIG.
In the configuration shown in FIG. 7, when the supply of the hydraulic oil to the hydraulic cylinders 50 and 52 is stopped, when the other hydraulic actuator 80 is operated, the hydraulic oil is supplied to the supply / discharge flow path 58. , The externally operated check valve 70
However, there is a problem that the transported object rises despite unexpectedness.

Therefore, an externally operated check valve 82 shown in FIG. 3 is used in place of the externally operated check valve 70 shown in FIG. This externally operated check valve 8
2 regulates the flow in both directions of the supply / discharge flow path 58,
When an excitation signal is input from outside, the restriction on the flow is released.

Accordingly, the other hydraulic actuator 80
Even when pressure interference occurs during supply and discharge of hydraulic fluid, the hydraulic cylinders 50 and 52 do not operate because the externally operated check valve 82 does not open.

[0009]

However, in the prior art shown in FIG. 3, the hydraulic cylinders 50, 52
When the control valve 60 is switched to supply the hydraulic oil from the hydraulic pump 62 to the supply / discharge flow path 58 in order to raise the transported object, the hydraulic oil pressure in the supply / discharge flow path 58 on the control valve 60 side is sufficient. If the externally operated check valve 82 is opened before ascending, the transported object may drop by its own weight. In order to prevent this, the timing of opening the externally operated check valve 82 is delayed rather than the switching of the control valve 60, and after the hydraulic oil pressure in the supply / discharge passage 58 is sufficiently increased, the externally operated check valve is opened. 82 is opened.

Therefore, in a state in which the flow is regulated by the externally operated check valve 82, the state in which the control valve 60 is switched and the hydraulic oil is supplied from the hydraulic pump 62 continues for a certain period of time. Therefore, during this time, the hydraulic pump 62 returns the hydraulic oil corresponding to the relief pressure to the hydraulic tank 64, and there is a problem that energy loss occurs.

An object of the present invention is to provide a hydraulic device in which energy loss is prevented from occurring.

[0012]

In order to achieve the above object, the present invention takes the following means to solve the problem. That is, in the hydraulic device in which the supply and discharge of the hydraulic oil to and from the working chamber of the hydraulic cylinder are switched by the control valve to move the transported body and the load by the transported body is applied to the hydraulic cylinder when the supply and discharge are stopped. A pair of externally operated check valves that can regulate the flow in one direction and that can release the regulation are interposed in the supply and discharge flow path between the chamber and the control valve in opposite directions. The hydraulic system is that.

[0013] The hydraulic cylinder may move up and down a loading attachment of a forklift. Further, the externally operated check valve may release the restriction on the one-way flow by inputting an excitation signal.

[0014]

Embodiments of the present invention will be described below in detail with reference to the drawings. The same members as those shown in FIGS. 2 and 3 are denoted by the same reference numerals, and detailed description will be omitted.

As shown in FIG. 1, reference numerals 1 and 2 denote externally operated check valves, which are supply and discharge passages 58 between the operation chambers 54 and 56 and the control valve 60, and further have fuse valves 72 and 74. And a flow control valve 66 and a flow control valve 66.
The two externally operated check valves 1 and 2 have the same structure, and include check valve positions 1a and 2a for restricting the flow in one direction and communication positions 1b and 2b for communicating the supply / discharge flow path 58. The two externally operated check valves 1 and 2 are switched to check valve positions 1a and 2a by the biasing forces of the built-in springs 4 and 6, and when an external excitation signal is input,
Communication position 1 by the action of built-in solenoids 8 and 10
b, 2b.

The externally operated check valve 1 is moved from the operation chambers 54 and 56 to the control valve 60 by the check valve position 1a.
It is interposed in the supply / discharge flow path 58 so that the flow of hydraulic oil to the supply / drain path is regulated. On the other hand, the other externally operated check valve 2 is interposed in the supply / discharge passage 58 so that the flow of hydraulic oil from the control valve 60 to the working chambers 54 and 56 is regulated by the check valve position 2a. Have been. Therefore, the two check valve positions 1a and 2a are arranged so as to regulate the flows in opposite directions.

Next, the operation of the above-described embodiment will be described. When raising the transported body, the control valve 60 is switched to supply the hydraulic oil from the hydraulic pump 62 to the supply / discharge flow path 58. At this time, an excitation signal is input to the other externally operated check valve 2 at the same time to switch to the communication position 2b. Even if the supplied operating oil pressure does not reach a sufficient pressure, the outflow of the operating oil from the working chambers 54, 56 is regulated by the one externally operated check valve 1, so that the hydraulic cylinders 50, 52 Even in the state where the load by the transport body is applied, the transported body does not drop.

When the operating oil pressure supplied from the hydraulic pump 62 reaches a sufficient pressure, the other externally operated check valve 2
The working oil is supplied to the working chambers 54 and 56 via the communication position 2b, the check valve position 1a of the externally operated check valve 1 and the fuse valves 72 and 74. As a result, the transported object rises.

When the transported object is lowered, the control valve 60 is switched, and at the same time, an excitation signal is input to one of the externally operated check valves 1 to switch to the communication position 1b. Therefore, the operating oil in the working chambers 54 and 56 is supplied to the fuse valves 72 and 74, the communication position 1b of the one externally operated check valve 1 and the check valve of the other externally operated check valve 2 due to the weight of the transported object. It is returned to the hydraulic tank 64 via the position 2a, the flow control valve 66, and the control valve 60. As a result, the transferred object is lowered.

When holding the transported object at that position,
Without inputting an excitation signal to both externally operated check valves 1 and 2, the externally operated check valves 1 and 2 are set to check valve positions 1a and 2a. Thereby, both working chambers 54, 56
The outflow of the hydraulic oil is regulated by the check valve position 1a of the one externally operated check valve 1. Therefore, the transported object does not descend by its own weight.

On the other hand, when the supply / discharge is stopped, another hydraulic actuator 80 is driven, and if hydraulic interference occurs, hydraulic oil is supplied from the control valve 60 to the supply / discharge passage 58. Even if hydraulic oil is supplied to the supply / drain passage 58, the action chamber 54,
Since the outflow to the side 56 is prevented, even if the operating oil pressure due to the oil pressure interference is high, the hydraulic cylinders 50 and 52 operate and the transported object does not rise unexpectedly.
In this circuit diagram, the hydraulic actuator is shown as a cylinder, but this is not limited to a cylinder, and another actuator such as a hydraulic motor may be used.

The present invention is not limited to such an embodiment at all, and can be implemented in various modes without departing from the gist of the present invention.

[0023]

As described in detail above, in the hydraulic device of the present invention, a pair of externally operated check valves are interposed in the supply / discharge flow path in opposite directions, so that the control valve and the other externally operated check valve are provided. Can be switched at the same time, and the effect of preventing the occurrence of energy loss can be achieved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of a hydraulic device as one embodiment of the present invention.

FIG. 2 is a hydraulic circuit diagram of a conventional hydraulic device.

FIG. 3 is a hydraulic circuit diagram of a conventional hydraulic device having another hydraulic actuator.

[Explanation of symbols]

 1, 2, 70, 82 ... externally operated check valve 50, 52 ... hydraulic cylinder 54, 56 ... working chamber 58 ... supply / discharge flow path 60 ... control valve 62 ... hydraulic pump 64 ... hydraulic tank 66 ... flow control valve 72, 74: fuse valve 80: hydraulic actuator

Claims (3)

[Claims] A control valve switches the supply and discharge of hydraulic oil to and from a working chamber of a hydraulic cylinder to move a body to be conveyed,
In a hydraulic device in which a load due to the conveyed object is applied to the hydraulic cylinder when supply / discharge is stopped, a flow in a supply / discharge flow path between the working chamber and the control valve is regulated in one direction, and the regulation is released. A hydraulic device characterized in that a pair of possible externally operated check valves are interposed in opposite directions. 2. The hydraulic device according to claim 1, wherein said hydraulic cylinder is for raising and lowering a cargo handling attachment of a forklift. 3. The hydraulic device according to claim 1, wherein the externally operated check valve releases the restriction on the flow in one direction by input of an excitation signal.