JPH0242716Y2 - - Google Patents

Description

[Detailed description of the invention] (1) Industrial application field The present invention relates to an overturn prevention device for an aerial work vehicle that is equipped with a work platform or a sub-boom that can swing freely at the tip of the boom.

(2) Prior art A fall prevention device that restricts the swinging operation of a work platform or sub-boom that is swingably provided at the tip of a boom is a conventional technology as described in, for example, Japanese Utility Model Application Publication No. 180900/1983. It is more well known.

(3) Problems that the invention aims to solve However, with the conventional overturn prevention device that restricts the swinging operation of the work platform or sub-boom, the swinging operation of the work platform or sub-boom is suddenly restricted by one limit switch. Therefore, when performing electrical work between obstacles such as electric wires, it may not be possible to move the work platform or sub-boom simply by operating in the direction that reduces the overturning moment when the regulation is activated, which may impair work efficiency. It was bad.

(4) Means for solving the problem In order to solve the above problem, the present invention provides an overturn prevention device for an aerial work vehicle that is equipped with a work platform or a sub-boom that can swing freely at the tip of the boom.
It is equipped with a limit switch that operates when the overturning moment acting on the boom reaches a limit value, and a limit reserve switch that operates before the limit value, and when the limit reserve switch is activated, the boom is moved in the direction where the overturning moment increases. When the limit switch is activated, the boom is not operated in a direction that increases the overturning moment, and the swinging operation of the work platform or sub-boom is also disabled.

(5) Effect With the above configuration, the operation regulation is performed by operating the limit reserve switch before the limit value.
The boom cannot be operated in the direction where the overturning moment increases, but the work platform or sub-boom can be oscillated, and then the limit switch is activated, which causes the boom to operate in the direction where the overturning moment increases. At the same time, the swinging operation of the work platform or sub-boom becomes impossible.

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

As shown in FIG. 2, the aerial work vehicle has a turntable 3 mounted on a vehicle body 1 supported by outriggers 2.
The base end of a telescopic boom 4 is pivotally supported on the turntable 3, and the telescopic boom 4 is extended and contracted by a built-in telescopic cylinder 6 and raised and lowered by an undulation cylinder 5. A work platform 7 and a sub-boom 8 of a lifting device are held in equilibrium at the tip of the telescopic boom 4, and the work platform 7 and sub-boom 8 swing around a vertical axis.

As shown in FIG. 1, a shut-off valve 25 is inserted into the conduit on the contracting side of the hoisting cylinder that connects the hoisting cylinder 5 and the hoisting operation valve 15, and a shut-off valve 25 is inserted in the conduit on the constriction side of the hoisting cylinder that connects the hoisting cylinder 5 and the hoisting operation valve 15. A shut-off valve 26 is inserted into the pipeline, and a pair of pipelines connecting the swing motor 9 that swings the workbench 7 via the worm gear 14 and the swing operation valve 19 are bypassed into which the shut-off valve 29 is inserted. They are connected by pipes. Shutoff valve 25
The solenoid of the shut-off valve 26 is connected to the power supply 11 via the limit standby switch 13, and the solenoid of the shut-off valve 29 is connected to the limit switch 12.
The limit standby switch 13 and the limit switch 12 are connected to the regulation signal generator 10, and the regulation signal generator 1
0 operates the limit reserve switch 13 when the overturning moment acting on the telescopic boom 4 reaches a certain percentage or a certain amount before the limit value, and operates the limit reserve switch 13 together with the limit reserve switch 13 when the overturning moment acting on the telescopic boom 4 reaches the limit value. This actuates the limit switch 12.

With the above configuration, when the overturning moment acting on the telescopic boom 4 is within the safe range, neither the limit standby switch 13 nor the limit switch 12 operates, so the shut-off valve 25 and the shut-off valve 26 are maintained in the communicating position. The shut-off valve 29 is held at the shutoff position, and the telescopic boom 4 can be raised and retracted, and the work platform 7 can be freely swung. When the overturning moment acting on the telescopic boom 4 approaches the limit value, the limit reserve switch 13 is activated.
When activated, the shut-off valve 25 and the shut-off valve 26 are switched to the cutoff position, and the telescopic boom 4
Although the raising and lowering operation of the telescopic boom 4 and the extending operation of the telescopic boom 4, which are operations in the direction of increasing the overturning moment acting on the telescopic boom 4, are disabled, the swinging operation of the work platform 7 is possible. Next, when the overturning moment acting on the telescopic boom 4 reaches a limit value, the limit switch 12 is activated together with the limit reserve switch 13.
The shutter-off valve 29 is switched to the communication position, and the raising/lowering operation of the telescopic boom 4 and the extending operation of the telescopic boom 4 are disabled, and the swinging operation of the work platform 7 is disabled.

Note that the swinging operation of the sub-boom can be restricted in the same manner as for the work platform 7 described above.

(7) Effects of the invention As described above, according to the invention, when the limit standby switch is activated, the operation of the telescopic boom is restricted, but the swinging operation of the work platform or sub-boom is possible. provides an overturn prevention device for aerial work vehicles with excellent workability, which can avoid obstacles and move the work platform to the safe side. It is valid.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is a circuit diagram showing the structure of the fall prevention device, and FIG. 2 is a side view showing the working state of the aerial work vehicle. 4...Telescopic boom, 7...Work platform, 8...Sub boom, 10...Restriction signal generator, 12...Limit switch, 13...Limit reserve switch, 25,2
6,29...Shutoff valve.

Claims (1)

[Scope of utility model registration request] A fall prevention device for an aerial work vehicle that is equipped with a work platform or sub-boom that can swing freely at the tip of the boom has a limit switch that activates when the overturning moment acting on the boom reaches a limit value, and a limit switch that activates before the limit value. and a limit reserve switch that disables operation of the boom in a direction in which the overturning moment increases when the limit reserve switch is activated, and in addition to operation of the boom in a direction in which the overturning moment increases when the limit reserve switch is activated. A fall prevention device for an aerial work vehicle, characterized by disabling the swinging operation of a work platform or sub-boom.