JPH0328077Y2 - - Google Patents

Description

[Detailed description of the invention] (1) Industrial application field The present invention relates to an emergency circuit for an aerial work vehicle that safely lowers a worker on the workbench to the ground in the event of an emergency.

(2) Prior art In an aerial work vehicle equipped with a work platform at the end of a boom that swings in the vertical direction, the work platform is equipped with a leveling valve that always maintains the work platform in an equilibrium state regardless of the swing of the boom. The balance maintaining device is, for example, as described in Japanese Utility Model Application Publication No. 60-61300,
It is conventionally known.

(3) Problems that the invention aims to solve However, in the conventional work platform balance maintaining device equipped with a leveling valve, if the hydraulic pump that sends pressure oil to the leveling valve or the drive device that operates the hydraulic pump fails, etc. When the pump becomes inoperable, if you try to lower the boom naturally to lower the worker on the platform to the ground, the platform balancing device will not operate because pressure oil is not supplied to the leveling valve. There was a problem with the work platform tilting as the boom lowered.

(4) Means for Solving the Problems In order to solve the above problems, the present invention includes a diversion valve connected to a hydraulic pump, and a valve connected to the diversion valve to discharge water from the hydraulic pump. A leveling valve to which pressurized oil is preferentially supplied, a leveling cylinder connected to this leveling valve, an operation valve connected to a diversion valve, an undulation cylinder connected to this operation valve, an operation valve and an undulation cylinder. A holding valve with a manual release inserted into a pipe connecting the oil chamber on the extension side of the valve, a pipe connecting the operating valve and the holding valve, and a pipe connecting the diversion valve and the leveling valve. It is equipped with a connecting pipe line and a stop valve inserted into the pipe line.

(5) Effect With the above configuration, if the hydraulic pump becomes inoperable, open the stop valve and manually open the holding valve to supply pressure oil from the oil chamber on the extension side of the hoisting cylinder to the leveling valve. As a result, the leveling cylinder also operates as the boom lowers, keeping the work platform in equilibrium at all times.

(6) Examples Examples of the present invention will be described below with reference to the drawings.

FIG. 2 shows an aerial work vehicle, in which a turntable 3 is provided on a vehicle body 1 supported by outriggers 2, the base end of a telescopic boom 4 is pivotally supported on this turntable 3, and the telescopic boom 4 is built-in. The telescopic boom 4 is expanded and contracted by a telescoping device (not shown), and is raised and lowered by the expansion and contraction of the hoisting cylinder 5. A workbench 6 is pivotally supported by a horizontal shaft at the tip of the telescopic boom 4, and between the boom tip and the workbench 6 is a A leveling cylinder 8 is attached to the workbench 6, and a leveling valve 7 is provided on the workbench 6 to control the leveling cylinder 8 by sensing the up and down movement of the telescopic boom 4 by the swinging of the workbench 6. , always maintain the workbench 6 in an equilibrium state.

FIG. 1 shows an emergency circuit, in which a hydraulic pump 10 driven by a prime mover 9 and a priority valve 11, which is a diversion valve, are connected by a conduit 16 equipped with a check valve 15.
is connected to the leveling valve 7 by a conduit 17, and is also connected to the operation valve 12 by a conduit 18, and supplies pressure oil discharged from the hydraulic pump 10 to the leveling valve 7 preferentially. The leveling valve 7 is connected to the leveling cylinder 8 by pipes 19 and 20, and the operating valve 12 is connected to the oil chambers on the extension side and contraction side of the undulating cylinder 5 by pipes 21 and 22, respectively. A holding valve 13 with manual opening is provided, and a pilot line 14 of the holding valve 13 is connected to a line 22. The operating valve 12 and holding valve 13 of the conduit 21 are connected to the conduit 17 by a conduit 23, and the conduit 23 is provided with a stop valve 15 that can be opened manually.

With the above configuration, normally, that is, when the prime mover 9 and the hydraulic pump 10 are operating normally,
Pressure oil discharged from the hydraulic pump 10 is supplied to the leveling valve 7 and the operating valve 12, and by switching the operating valve 12, the hoisting cylinder 5 extends or contracts, raising and lowering the telescopic boom 4. A leveling valve 7 senses the up-and-down movement due to the rocking of the work platform 6 and controls a leveling cylinder 8 to always maintain the work platform 6 in an equilibrium state regardless of the up-and-down movement of the telescopic boom 4. If the prime mover 9 or hydraulic pump 10 breaks down during work and becomes inoperable, the aerial work vehicle
Since the telescopic boom 4 shown in the figure is held in an upward position, the worker on the workbench 6 cannot get down to the ground. Therefore, when the stop valve 15 is manually opened and the holding valve 13 is manually opened, the luffing cylinder 5 is compressed by the weight of the telescopic boom 4, etc., so the luffing cylinder 5 is contracted, and the luffing cylinder 5 is compressed. 5 is supplied to the leveling valve 7 through the holding valve 13, pipe line 21, pipe line 23, stop valve 15, and pipe line 17, and the leveling valve 7 is connected to the work platform by lowering the telescopic boom 4. The leveling cylinder 8 is controlled by sensing the rocking of the workbench 6, and the workbench 6 is brought into an equilibrium state. Therefore, the telescopic boom 4 is lowered, and the worker on the work platform 6 can descend to the ground.

Furthermore, when it is desired to increase the descending speed of the telescopic boom 4, as shown in FIG. Line 26 with a throttle valve 25 between 15
By connecting this conduit 26 to the tank 27, the descending speed of the telescopic boom 4 can be increased.

Although a priority valve is used as the flow dividing valve in the above embodiment, it is also possible to use a flow divider or the like.

(7) Effects of the invention As described above, according to the invention, an emergency circuit for an aerial work vehicle that has a simple structure can always maintain the work platform in equilibrium even when the boom is lowered naturally. The present invention is effective in improving the safety of aerial work vehicles.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, Fig. 1 is a hydraulic circuit diagram showing an emergency circuit, Fig. 2 is a side view of an aerial work vehicle, and Fig. 3 is a hydraulic diagram of an emergency circuit showing another embodiment. It is a circuit diagram. 5... Lifting cylinder, 7... Leveling valve, 8... Leveling cylinder, 10... Hydraulic pump, 11... Priority valve, 12...
Operation valve, 13...Holding valve, 1
5...stop valve.

Claims (1)

[Scope of utility model registration request] A diversion valve connected to a hydraulic pump, a leveling valve connected to the diversion valve to which pressure oil discharged from the hydraulic pump is preferentially supplied by the diversion valve, a leveling cylinder connected to the leveling valve, and a diversion valve. An operating valve connected to the valve, a hoisting cylinder connected to the operating valve, a holding valve with a manual release inserted into a pipe connecting the operating valve and the extension side oil chamber of the hoisting cylinder, and an operating valve. A high place comprising: a pipe line connecting the valve and the holding valve; a pipe line connecting the diverter valve and the leveling valve; and a stop valve inserted into the pipe line. Emergency circuit for work vehicles.