JPH0738317Y2 - Aerial work vehicle - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to an aerial work vehicle in which a boom is arranged on a vehicle so as to be capable of undulating and retracting, and a bucket for mounting a worker is arranged at the tip of the boom. It is a thing.

(Prior Art) A conventional aerial work vehicle of this type will be described below with reference to FIGS. 3 and 4. In FIG. 3, a work platform for an aerial vehicle has a boom 2 arranged on a vehicle 1 so as to be capable of undulating and extending and contracting, and a bucket 3 for worker riding is attached to a tip portion of the boom 2.
Are arranged. That is, the boom 2 includes a base boom 4, an intermediate boom 5 and a front boom 6, and the base boom 4
The intermediate boom 5 is inserted into the intermediate boom 5, the front boom 6 is inserted into the intermediate boom 5, and expansion / contraction means (not shown) such as a hydraulic cylinder is arranged between the booms.
The front boom 6 is configured to be extendable and retractable with respect to the intermediate boom 5. A swivel base 7 is rotatably arranged on the vehicle 1, and the base end of the base boom 4 is pivotally supported on the swivel base 7.
A hoisting cylinder 8 is arranged between the swivel base 7 and the base boom 4 in an appropriate position so that the base boom 4 can be hoisted with respect to the swivel base 7. Therefore, in the aerial work vehicle configured as described above, an operator who rides on the bucket 3 moves the boom 2 up and down and extends and retracts the boom 3 to position the bucket 3 at a high place, and This allows work to be performed at a high place.

By the way, in general, in order to allow a worker to get into the bucket 3 from the ground, the above-mentioned work platform has a structure in which the boom 2 is extended below a predetermined level, and then the boom 2 is laid down.
Can be located near the ground. That is, the stability is ensured so that the vehicle 1 does not fall down even if the boom 2 is laid down when the boom 2 is extended to a predetermined extent or less.

On the other hand, when working with the aerial work vehicle, the vehicle 1 cannot be secured due to the ups and downs of the boom 2 and the telescopic state of the boom 2 may cause the vehicle 1 to fall. A safety device 9 as shown in the figure is provided. The safety device 9 will be described below with reference to FIG. The safety device 9 includes a fall prevention device 10 that determines whether the vehicle 1 is stable or unstable depending on the ups and downs of the boom 2. The tipping prevention device 10 stores in advance the stable and unstable states of the vehicle 1 according to the state of the boom 2, and receives signals from the boom length detector 11 and the hoisting angle detector 12 to which the boom 2 is attached. Thus, it is determined whether the current state of the boom 2 is stable or unstable. When the boom 2 is in a stable state, the fall prevention device 10 constantly outputs the output signal to the solenoid valve 13
When the state of the boom 2 becomes unstable, the output signal from the fall prevention device 10 is cut off so that the solenoid valve 13 is not activated. Solenoid valve 13
The hydraulic circuit that moves the boom 2 up and down and expands and contracts is used in the vent circuit that unloads the boom 2. When the boom 2 is lifted and expanded and contracted, the boom 2 can be expanded and contracted when it is not operated. It is located in. The switch 14 is a switch that is turned on when a hoisting operation lever (not shown) for hoisting the boom 2 is operated to the elevation side. Similarly, the switch 15 is a switch that is turned on when an expansion / contraction operation lever (not shown) for expanding and contracting the boom 2 is operated toward the contraction side. These switches 14 and 15 are connected in parallel via a switch 16 and a switch 17, which will be described later, and are connected between a power source and the solenoid valve 13 so that the solenoid valve 13 operates regardless of which switch is turned on. There is. The switches 14 and 15 are arranged for the following purpose. That is, when the boom 2 becomes unstable, the fall prevention device 10 causes the solenoid valve to
In order to return the boom 2 to the safe side when the output signal is no longer output to the boom 13 and the movement of the boom 2 is stopped, the solenoid valve 13 is connected from a circuit separate from the fall prevention device 10 when raising and retracting the boom 2. It is arranged in order to operate and allow the movement of the boom 2 to the safe side.
Next, the switch 16 is a switch that is turned on only when the up-and-down operation lever is in the neutral position, and the switch 17 is a switch that is turned on only when the telescopic operation lever is in the neutral position. These switches 16 and 17 are arranged to prevent the boom 2 from being operated in the following manner when the boom 2 is returned to the safe side when the fall prevention device 10 operates and the movement of the boom 2 is stopped. is there. That is, in order to return the boom 2 to the safe side, the operation of the boom 2 is disabled when the boom 2 is tilted while the boom 2 is being contracted or when the boom 2 is extended while the boom 2 is being raised. It is something to do. Further, in the above aerial work vehicle, the aerial work vehicle having only the function of allowing the worker to ride on the bucket 3 to work has been described. For aerial work vehicles in which the load to be worked is lifted near the boarding worker, the safety device 10
Are configured. That is, since the overturning moment is increased by the hoisting load as compared with the above-mentioned work vehicle at high places, a moment detector 18 (for example, the load supported by the hoisting cylinder 8 is detected) is arranged.
A signal from 18 and signals from the boom length detector 11 and the hoisting angle detector 12 are received to determine whether the vehicle 1 is stable or unstable.

(Problems to be solved by the invention) However, in the aerial work vehicle described above, an operator rides on the bucket 3 and hoists and retracts the boom 2 as needed to position the bucket 3 at a high place. In this case, the fall prevention device 10 of the safety device 9 may break down, and the output signal may not be output to the solenoid valve 13 even though the state of the boom 2 is stable and the vehicle 1 does not fall. Therefore, the operator who has boarded the bucket 3 once descends to the ground and attempts to inspect the malfunction and to reduce and collapse the boom 2. However, although the boom 2 can be contracted by the switch 15, only the raising and lowering operation by the switch 14 can be performed for raising and lowering the boom 2, and the tilting operation cannot be performed. Therefore, the above-described work platform for aerial vehicles has a problem that an operator who rides on the bucket 3 cannot get on the ground when the safety device fails.

The aerial work vehicle of the present invention is intended to provide a new aerial work vehicle that solves the above problems.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the aerial work vehicle of the present invention has a boom arranged on the vehicle so as to be capable of undulating and extending and retracting, and a boom is mounted on the tip of the boom for an operator to ride. An aerial work vehicle, in which a bucket can be arranged and the stability of the vehicle can be ensured even when the boom is laid down when the boom is extended below a predetermined level. In an aerial work vehicle equipped with a safety device that prevents the boom from moving toward the dangerous side when the boom is positioned in a state where the vehicle cannot be secured due to the expansion and contraction state, the vehicle is stable even when the boom is laid down. When a boom is in the above state is detected by this detector, a boom-related control by the safety device is provided. It is characterized in that it is configured to release.

(Operation) The aerial work vehicle of the present invention having the above-described configuration is safe when the detector detects the extension state of the boom below a predetermined level when the stability of the vehicle is ensured even when the boom is laid down. Since the boom-related control by the device is canceled, the boom can be moved regardless of the control of the safety device when the boom is extended below a predetermined level. Therefore, even if the safety device fails, if the boom is extended below the specified level,
The boom can be laid down in a stable state without overturning the vehicle, and the worker who has boarded the bucket can get down to the ground.

(Embodiment) An embodiment of an aerial work vehicle of the present invention will be described below with reference to FIGS. 1 and 2. It should be noted that the reference numerals 1 to 18 shown in FIGS. 3 and 4 and described in the related art will be used in the following description with the same reference numerals. Therefore, description of reference numerals 1 to 18 will be omitted here. In FIG. 1, reference numeral 19 is a detector that detects a stretched state of the boom 2 below a predetermined level when the stability of the vehicle 1 is ensured even when the boom 2 is laid down, and is composed of a switch. (Hereinafter detector
The switch 19 will be described as a switch 19. ) The switch 19 is arranged on the boom length detector 11 so as to be turned on when the boom 2 is in a stretched state below a predetermined level. As shown in FIG. 1, the switches 14 and 15 are connected in parallel. Note that FIG. 1 is different from that shown in FIG. 4 and described in the prior art only in the arrangement of the switch 19.

The aerial work vehicle according to the present invention in which the switch 19 is arranged in this manner operates as follows. When a worker is currently riding on the bucket 3 and hoisting and retracting the boom 2 to position the bucket 3 at a high position, the fall prevention device 10 of the safety device 9 fails and the solenoid valve 13 falls over. Prevention device
Suppose that the output signal is no longer output from 10. In this case, the boom 2 which may cause the vehicle 1 to fall over cannot be extended and fallen, but the switch 14 and the switch 15 can reduce and elevate the boom 2 for ensuring the stability of the vehicle. Therefore, the worker who has boarded the bucket 3 first reduces the boom 2 in order to get off the ground once. Then, the solenoid valve 13 operates by receiving the power supply from the switch 15, so that the boom 2 is contracted. When the boom 2 is contracted and the boom 2 is in a stretched state below a predetermined value, the switch 19 is turned on, and the switch 19 supplies power to the solenoid valve 13.
After the boom 2 is extended to a predetermined extent or less and then the boom 2 is laid down, the solenoid 2 is operated at this time, and the boom 2 is laid down. Then, the worker who puts the bucket 3 near the ground and boarded the bucket 3 is
You can get to the ground more. Moreover, when the boom 2 is extended to a predetermined extent or less, the stability of the vehicle 1 is ensured, and even if the boom 2 is laid down, the vehicle 1 does not fall and the worker can safely get down to the ground. . Therefore, the aerial work vehicle according to the present invention is capable of lowering the bucket 3 near the ground even if the safety device 9 is out of order by keeping the boom 2 in an extended state below a predetermined level.

Although the switch 19 is arranged on the boom length detector 11 in the above-mentioned embodiment, it is arranged between the base boom 4 and the intermediate boom 5 and between the intermediate boom 5 and the front boom 6, respectively.
Or it turns on when the extension state of the tip boom 6 falls below a predetermined level.
You may arrange so that it may become. Further, in the simultaneous expansion and contraction method in which the extension state of the intermediate boom 5 with respect to the base boom 4 and the extension state of the front boom 6 with respect to the intermediate boom 5 are simultaneously extended and contracted by the same amount, the switch 19 is It may be arranged only between the boom 4 and the intermediate boom 5. Further, in the above-described embodiment, when the boom 2 is in a stretched state below a predetermined level, it is possible to perform the fall operation of the boom 2 regardless of the control of the safety device 9, but the control range of the safety device 9 is made as wide as possible. If you want to keep it, switch 19 is
It should be set so that it turns on only when boom 2 is fully retracted.

Next, another embodiment of the aerial work vehicle according to the present invention will be described with reference to FIG. The safety device 9 shown and described in FIG.
Although it is a fail-safe system, the one shown in FIG. 2 is one in which a solenoid valve is operated when stability is not ensured. In FIG. 2, reference numeral 20 is a safety device, which is different from the safety device 9 shown in FIG. 1 in that it is not a fail safe system. Reference numeral 21 denotes a fall prevention device, which differs from the fall prevention device 10 only in that it outputs a control output signal in reverse. That is, the control output signal is cut off when the boom 2 is in a stable state, and is output when the boom 2 is in an unstable state. Reference numeral 22 denotes a solenoid valve which unloads a hydraulic circuit that raises and lowers and expands and contracts the boom 2 when actuated, and is also arranged so as to act in the opposite manner to the solenoid 13 described above. Reference numerals 14 'and 15' denote switches that are activated when operated in the same manner as the switches 14 and 15 described above. And a control output signal is output by the fall prevention device 21, and when the operation of the boom 2 is disabled by the operation of the solenoid valve 22, it is arranged so that it can be operated on the safe side. Is. Reference numeral 23 denotes a switch that is turned off when the up-and-down operation lever is in the neutral position, and is arranged in parallel with the switch 15 '. Reference numeral 24 denotes a switch that is turned off when the telescopic operation lever is in the neutral position, and is arranged in parallel with the switch 14 '. These switches 23 and 24 are the switches 1
6, the switch 17 is arranged for the same purpose, and detailed description thereof is omitted. 25 operates like the switch 19 when the boom 2 is in a stretched state below a predetermined level,
On the contrary to the switch 19, it is a switch that is turned off. Since it is clear that the aerial work vehicle of the second embodiment configured in this manner also operates in the same manner, the description of the operation will be omitted.

(Advantages of the Invention) Since the aerial work vehicle of the present invention is configured and operates as described above, the boom can be moved regardless of the control of the safety device when the boom is extended below a predetermined level. Therefore, even if the safety device fails, the boom can be laid down in a stable state without overturning the vehicle if the boom is extended below the predetermined level, and the operator on the bucket can descend to the ground. Can be

[Brief description of drawings]

FIG. 1 is an explanatory view of an aerial work vehicle according to the present invention, FIG. 2 is an explanatory view of another embodiment of an aerial work vehicle according to the present invention, and FIG. 3 is an explanation of an aerial work vehicle. FIG. 4 and FIG. 4 are explanatory views of a conventional aerial work vehicle. 1: Vehicle, 2: Boom, 3: Bucket, 9, 20: Safety device, 1
9, 25: Detector

Claims (1)

[Scope of utility model registration request] 1. A boom is arranged on a vehicle so as to be capable of undulating and expanding and contracting, a bucket for mounting a worker is arranged at a tip end of the boom, and the boom is laid down when the boom is extended below a predetermined level. Even if the boom is positioned in a state where the vehicle cannot be secured due to the ups and downs of the boom and the telescopic state of the boom, the danger side of the boom is In an aerial work vehicle equipped with a safety device that makes it impossible to move to, a detector is provided for detecting an extension state of the boom below a predetermined level when the stability of the vehicle is ensured even when the boom is laid down, An aerial work vehicle configured to release the boom-related control by the safety device when the detector detects that the boom is in the above state.