JPH0242717Y2 - - 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.
A regulation signal generator that generates a limit signal when the overturning moment acting on the boom reaches a limit value, and generates a limit preliminary signal before the limit value, and a control signal generator that generates a limit signal when the overturning moment acting on the boom reaches a limit value, and a control signal generator that generates a limit signal when the overturning moment acting on the boom reaches a limit value, and a control signal generator that generates a limit signal when the overturning moment acting on the boom reaches a limit value, and a control signal generator that generates a limit signal when the overturning moment acting on the boom reaches a limit value, and a control signal generator that generates a limit preliminary signal when the overturning moment acting on the boom reaches a limit value. and a detection device that generates a detection signal when the work platform or sub-boom is not in the extension direction of the boom according to the signal from the detection device, the control signal generation device generates a limit preliminary signal. When a limit signal is generated, the boom operation in the direction in which the overturning moment increases is disabled, and in addition to the boom operation in the direction in which the overturning moment increases, the swinging operation of the work platform or sub-boom is disabled. If the oscillation position of the work platform or sub-boom is in the direction of boom extension due to the signal from It is something.

(5) Effect With the above configuration, the operation is restricted by generating a limit preliminary signal before the limit value, and if the swing position of the work platform or sub-boom is not in the direction of extension of the boom, the overturning moment will be reduced. The boom becomes incapable of operating in the direction in which If the oscillation position of the work platform or sub-boom is not in the boom extension direction due to the generation of a limit signal, the boom cannot be operated in the direction where the overturning moment increases, and If the swing operation of the work platform or sub-boom becomes impossible and the swing position of the work platform or sub-boom is in the direction of extension of the boom, only the boom operation in the direction where the overturning moment increases will become impossible and work will be interrupted. The swinging operation of the platform or sub-boom is not regulated.

(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 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 the circuit diagram shown in FIG.
A shaft-off valve 25 is inserted into a conduit on the undulating cylinder contraction side that connects the undulating cylinder 6 and the undulating operation valve 15, and a shaft-off valve 26 is inserted in a duct on the telescopic cylinder contraction side that connects the telescopic cylinder 6 and the telescopic operation valve 16. A pair of pipes connecting the swinging motor 9 for swinging the workbench 7 via the worm gear 14 and the swinging operation valve 19 are connected by a bypass pipe into which a shutoff valve 29 is inserted. The aerial work vehicle generates a limit preliminary signal when the overturning moment acting on the telescopic boom 4 reaches a certain percentage or a certain amount before the limit value, and when the overturning moment acting on the telescopic boom 4 reaches the limit value, the limit value is reached. Regulation signal generator 1 that generates a limit signal together with a preliminary signal
0 is provided on the workbench 7, and detects whether the swinging position of the workbench is on the extension direction of the boom or not, and outputs a detection signal when the swinging position of the workbench is on the extension direction of the boom. The solenoid of the shutoff valve 29 is connected in series with the first limit switch 121 which is the A contact and the B
It is connected to the power supply 11 via the first detection switch 231 which is a contact, and the solenoids of the shutoff valve 25 and the shutoff valve 26 connect the limit standby switch 13 which is an A contact and the second detection switch 232 which is a B contact in series. The connected circuit, the second limit switch 122 which is the A contact, and the third limit switch 122 which is the A contact
A circuit in which detection switches 233 are connected in series is connected to the power supply 11 through a circuit connected in parallel, and the first limit switch 121 and the second limit switch 122 detect the limit from the regulation signal generator 10. The limit reserve switch 13 is operated by a limit reserve signal from the regulation signal generator 10, and the first detection switch 231, second detection switch 232, and third detection switch 233 are operated by a limit reserve signal from the detection device 22. Activated by detection signal.

With the above configuration, when the overturning moment acting on the telescopic boom 4 is within the safe range, the limit reserve switch 13 and the limit switches 121, 122 are activated.
Since none of the
The shutter-off valve 26 is held in the communicating position, and the shut-off valve 29 is held in the blocking position, so that the telescopic boom 4 can be raised, extended and contracted, and the work table 7 can be freely swung, regardless of the swing position of the work table 7. be able to. When the overturning moment acting on the telescopic boom 4 approaches the limit value and the regulation signal generator 10 generates a limit reserve signal and the limit reserve switch 13 is activated, the swing position of the work platform 7 is not in the direction of extension of the boom. When the second detection switch 232
is held in the ON state, shut-off valve 2
5 and the shut-off valve 26 are switched to the cutoff position, and the raising/lowering operation of the telescopic boom 4 and the extending operation of the telescopic boom 4, which are operations that increase the overturning moment acting on the telescopic boom 4, are disabled. When the swinging position of boom 7 is in the direction of extension of the boom, the second detection switch 232 is kept in the OFF state by the detection signal from the detector 22, so the operation of the telescopic boom 4 is not restricted. Next, when the overturning moment acting on the telescopic boom 4 reaches a limit value and the regulation signal generator 10 generates a limit signal, and the limit signals 121 and 122 are activated,
When the swing position of the work platform 7 is not in the extension direction of the boom, the first detection switch 231 is held in the ON state, so the shut-off valve 29 is switched to the communication position, and the telescopic boom 4 is operated to raise and lower. The extension operation of the telescopic boom 4 becomes impossible, and the swinging operation of the work platform 7 becomes impossible. However, when the swinging position of the work platform 7 is on the extension direction of the boom, the first
detection switch 231 and second detection switch 2
32 is held in the OFF state and the third detection switch 233 is held in the ON state, the shut-off valves 25 and 26 are switched to the cutoff position, and the overturning moment acting on the telescopic boom 4 is increased. Only the raising and lowering operations of the telescopic boom 4 and the extending operations of the telescopic boom 4 are disabled, but the swinging operation of the work platform 7 is possible.

Note that the swinging operation of the sub-boom 8 can be restricted in the same manner as the work platform 7 described above.

(7) Effects of the invention As described above, according to the invention, the preliminary limit signal is generated before the limit value, so that if the swing position of the work platform or sub-boom is not in the direction of extension of the boom, , the boom cannot be operated in the direction where the overturning moment increases, but the platform or sub-boom can be oscillated, and if the oscillation position of the platform or sub-boom is in the direction of boom extension, the boom The operation of the is also not regulated,
Next, when a limit signal is generated, if the swing position of the work platform or sub-boom is not in the boom extension direction, the boom cannot operate in the direction where the overturning moment increases, and the work platform or If the sub-boom oscillation becomes impossible and the oscillation position of the work platform or sub-boom is in the direction of extension of the boom, only the boom operation in the direction where the overturning moment increases becomes impossible, and the work platform or sub-boom oscillates. Since the swinging operation of the work platform or sub-boom is not regulated, the operation of the telescopic boom is restricted when the limit reserve switch is activated, but the swinging operation of the work platform or sub-boom is possible. The present invention provides a fall prevention device for a vehicle working at height that can move a work platform to a safe side and has excellent workability, and is effective in improving the workability of a vehicle for work at height.

[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...Workbench, 8...Sub boom, 10...Restriction signal generator, 13...Limit reserve switch, 22...Detection device, 25,2
6, 29... Shutoff valve, 121, 122...
...Limit switch, 231, 232, 233...Detection switch.

Claims (1)

[Scope of utility model registration request] In an overturn prevention system for an aerial work vehicle that is equipped with a removable work platform or sub-boom at the tip of the boom, a limit signal is generated when the overturning moment acting on the boom reaches a limit value, and a limit reserve signal is generated before the limit value. It is equipped with a regulation signal generator that generates a signal, and a detection device that generates a detection signal when the swing position of the work platform or sub-boom is on the extension direction of the boom. If the oscillation position is not in the direction of extension of the boom, the control signal generator disables the boom from operating in the direction in which the overturning moment increases when the limit preliminary signal is generated, and the overturning moment increases when the limit signal is generated. In addition to the boom operation in the increasing direction, the swing operation of the work platform or sub-boom is disabled, and if the swing position of the work platform or sub-boom is in the direction of extension of the boom based on the signal from the detection device, a restriction signal is issued. An overturn prevention device for an aerial work vehicle, characterized in that when a generator generates a limit signal, it is impossible to operate a boom only in a direction in which overturning moment increases.