JPS58216891A - Safety device for operation of hydraulic type crane - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention connects the discharge end of a hydraulic pump to a boom hoisting cylinder and other actuators via a control valve,
The present invention relates to an operation safety device for a hydraulic crane that stops operation via a pressure switch that closes when the hydraulic pressure in the raising edge chamber of a boom raising/lowering cylinder exceeds a set pressure.

First, an example of a hydraulic crane having a crane mounted on a vehicle body will be explained with reference to FIG.

A crane post 2 is rotatably mounted on a crawler-type traveling vehicle body 1, and a first boom 3, which is raised and lowered by a raising and lowering cylinder (hydraulic cylinder) 4, is connected to the crane post 2' by a pin 5. The base end of the undulating cylinder 4 is supported by the lower part of the crane post 2, and the tip of its piston rod is connected to the base end of the first boom 3 by a pin 6. A second boom 7 is slidably inserted into the first boom 3 and is extendable and retractable by a telescopic cylinder (described later), and the tip of the second boom 7 is hoisted and rolled up by a winch 9 installed on the base end of the first boom 3. One end of the hoisting rope is connected.

A hook 8 for hoisting a suspended load 10 is suspended from the hoisting rope.

Next, an example of a conventional hydraulic circuit and electric signal circuit of this type of hydraulic crane will be explained with reference to FIG.

The suction side of the hydraulic pump 14 is connected to the oil tank 15, and the discharge side is connected to the first control valve 17, second control valve 18, third control valve 19, and fourth control valve 20 of the control valve device 16. The return line of each control valve 17 , 18 , 19 , 20 is connected to the oil tank 15 .

The operating port of the first control valve 17 is connected to the raising edge chamber 4a and the lowering edge chamber 4b of the luffing cylinder 1 by a pipe, and the operating port of the second control valve 18 is an expandable/retractable port that extends and retracts the second boom 7. Extension chamber 11a% contraction chamber 11b of cylinder 11
The operating port of the third control valve 19 is connected to the winch 9.
The hoisting port of the hydraulic motor 12 that rotates the
The operating port of the -4 control valve 2o is connected to the lower port 12b, and the operating port of the -4 control valve 2o is connected to the hydraulic motor 1 for rotating the crane post 2.
The right-hand turning side port and the left-hand turning side port of the motor 13 are connected to the ゎport. Electromagnetic switching valves 22, 23, and 24 are provided in the hydraulic conduit for the lying side of the undulating cylinder 4, the extending hydraulic line for the telescopic cylinder 11, and the conduit for hoisting the hydraulic motor 12, respectively.
Solenoids 22c, 23c, and 24c of each electromagnetic switching valve 22, 23, and 24 are connected to one terminal of a pressure switch 21 by an electric circuit, and the pressure switch 21 is connected to one terminal of a pressure switch 21. The circuit is designed to close when the oil extraction pressure exceeds a set value (allowable moment of sag and -n), and the other terminal is connected to the power source 25. Each electromagnetic switching valve 22, 23, 24 has a spring 22d, 23d, respectively.

Equipped with 24d, solenoid 22G, 23C, 2
If 4C is demagnetized, the umbrella will have 22a,';13a
s 24 a position, allowing pressure oil to flow in either direction of the pipe. Solenoid 22c, 2
When 3c and 24c are excited, each electromagnetic switching valve 22.23
．． 24 are switched to the positions 22b, 23b, and 24b, respectively, so that oil flows only from the downward oil chamber 4b, the extended oil chamber 11a1, and the upper side ports 12, a to each control valve 17, 18, and 19. You will get it.

When the pressure switch 21 closes, the electric signal causes each electromagnetic switching valve 22, 23, 24 to close 22b, 2 as described above.
Operation in which the load (moment) of the crane is increased by switching to the positions 3b and 24b, that is, the boom is placed down,
The extension of the second boom 7 eliminates the need to hoist the suspended load 10. However, the opposite operation, that is, an operation that reduces the load, is possible.

The hydraulic circuit of the above-mentioned hydraulic crane requires three electromagnetic switching valves and is therefore expensive. This invention provides crane operation safety by dynamically stopping the operation of the crane through a single solenoid valve and safely canceling the stoppage of the operation. The purpose is to provide a device.

This invention is intended to achieve the above object, and the discharge side of a hydraulic pump is connected to a boom hoisting cylinder and other actuators via a control valve, so that the hydraulic pressure in the hoisting side chamber of the boom hoisting cylinder is controlled. In a hydraulic crane that stops operation via a pressure switch that closes when the pressure exceeds a set pressure, if there is no electrical signal from the pressure switch in the pipeline between the discharge side of the hydraulic pump and the control valve, the hydraulic A safety electromagnetic switching valve is provided that connects the discharge side of the pump to the control valve, and is switched by an electric signal caused by the closing of the pressure switch to connect the discharge side of the hydraulic pump to the oil tank. The electric signal circuit with the electromagnetic switching valve is equipped with a normally closed open push button switch.

In the configuration of this invention, when the pressure switch closes,
The oil discharged from the hydraulic pump flows into the oil tank, and the crane operation stops. The crane can be operated to reduce the load by pressing the release pushbutton.

Hereinafter, one embodiment of the present invention will be explained with reference to FIG.

In this figure, the same reference numerals as in FIG. 2 represent the same or equivalent items.

An electromagnetic switching valve 26 equipped with a spring 26d is provided in the pipeline between the discharge side of the hydraulic pump 14 and the control valve device 16, and one terminal of the pressure switch 21 is connected to a double push button switch 27. It is connected to the solenoid 26c of the electromagnetic switching valve 26 through an electric circuit into which a normally closed contact 27a is inserted, and is also connected to a buzzer 28 via a normally open contact 27b. The electromagnetic switching valve 22, 23 shown in FIG.
24 is not provided. Others are the same as those in FIG.

When the pressure switch 21 is open, the electromagnetic switching valve 26 is in the position 26a by the spring 26d. That is, the oil discharged from the hydraulic pump 14 is transferred to the electromagnetic switching valve 26.
It is now in a state where it flows into the control valve device 16 through the. In this state, by operating each control valve 17, 18, 19. 2o, the hoisting cylinder 4, the telescopic cylinder 11°, the hydraulic motor 12, and the hydraulic motor 13 are operated, causing an overload on the crane. When the oil pressure in the oil chamber 4a of the boom raising/lowering cylinder 1 reaches a set value or more, the pressure switch 21 closes. As a result, current from the power source 25 flows to the solenoid 26c, the electromagnetic switching valve 26 is switched to the position 26b, and the oil discharged from the hydraulic pump 14 flows into the oil tank 15 through the passage of the electromagnetic switching valve 26, so that the crane stops.

When the crane is operated to reduce the load, the push button switch 27 is pressed to open the contact 27a and close the contact 27b.

At this time, the solenoid 26c is demagnetized and the electromagnetic switching valve 26
The position of 26a is returned, and the current from the power supply 25 is turned off to the buzzer 2.
8, and the alarm sounds. In this state, actions are taken to reduce the load on the crane.

Then, when the crane is released from the overloaded state, the pressure switch 21 is opened and the buzzer 28 stops sounding. In this state, even if you stop pressing the push button switch 27,
The electromagnetic switching valve 26 is moved to the position 26a by the spring 26d, allowing normal operation.

According to the invention described above, the following effects can be obtained.

(1) Previously, three electromagnetic switching valves were used, but one
(2) Operation stoppage can be easily canceled by operating a push button switch. In addition, since it is a push button switch, the crane will not operate in the overload range unless the crane operator consciously presses the switch, ensuring safety. When operating the crane from the load area to the safety area (for example, shortening the boom or raising the boom to shorten the reach, or lowering a suspended load to the ground), the buzzer will sound an alarm. It is necessary to alert the operator. And if it becomes a safe area,
Since the pressure switch closes and the buzzer stops sounding, it is easy to confirm that the safety range has been reached.

[Brief explanation of the drawing]

Figure 1 is a side view showing an example of a hydraulic crane with a crane mounted on a crawler-type traveling body, Figure 2 is a diagram showing the hydraulic circuit and electric signal circuit of a conventional crane operation safety device, and Figure 3 is a diagram of this hydraulic crane. FIG. 3 is a diagram showing a hydraulic circuit and an electric signal circuit of the crane operation safety device according to the invention. 1. Crawler type traveling vehicle body, 2. Crane post, 3. First boom, 4 @ Lifting cylinder, 7. Second boom, 9II. Winch.
11@・Telescopic cylinder, 12・Hydraulic motor,
13・Φhydraulic motor, 14・hydraulic pump, 15
・・Oil tank, 16・・Control valve device, 17・・First control valve, 18・・Second control valve, 19・Φ3rd control valve, 20・・Fourth control valve, 21・・Pressure filter・25...power supply, 26...electromagnetic switching valve, 27...push button switch, 27a--normally closed contact, 27b...
・Normally open contact, 28... Figure 1 Figure 3

Claims (2)

[Claims] (1) The discharge side of the hydraulic pump is connected to the boom hoisting cylinder and other actuators via a control valve, and the circuit is closed via a pressure switch that closes when the hydraulic pressure in the boom hoisting side chamber of the boom hoisting cylinder exceeds a set pressure. In a hydraulic crane whose operation is to be stopped, if there is no electric signal from the pressure switch, connect the discharge side of the hydraulic pump and the control valve to the pipeline between the discharge side of the hydraulic pump and the control valve. , a safety electromagnetic switching valve is provided that is switched by an electrical signal caused by the closing of the pressure switch to connect the discharge side of the hydraulic pump to the oil tank, and a normally closed electrical signal circuit between the pressure switch and the safety electromagnetic switching valve is provided. A driving safety device characterized by being provided with a push button switch for opening. (2) Connect a normally open contact that operates simultaneously with the normally closed contact for opening in (1) to the 4-signal output of the pressure switch, and connect an alarm buzzer to the output of the normally open contact. Driving safety device.