JPH0718716Y2 - Lifting device for aerial work vehicles - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention relates to a hoisting device which is mounted on a boom tip of an aerial work vehicle so that the hoisting device can be hoisted. The operability is improved by making it possible to perform.

(Prior Art) A hoisting device having a horizontal support member having a workbench attached to the tip of a boom that can be raised and lowered so as to always maintain a horizontal posture, and a sub-jib on a mounting base provided on the upper part of the horizontal support member. As a hoisting device for an aerial work vehicle that can be undulated in the vertical plane and can be fixed to any undulating position by a fixing device, as described in Japanese Utility Model Laid-Open No. 63-142391 It is known that a damper cylinder is interposed between the lifting device and the hoisting device, and a part of the turning power of the hoisting device is shared and supported by the damper cylinder to reduce the hoisting operation force of the hoisting device. There is.

(Problems to be solved by the invention) However, in the conventional hoisting device, since the turning force is supported by the damper cylinder to which the extension force is applied by the enclosed gas pressure, a sufficient supporting force is obtained. However, there is a problem in that the effect of reducing the undulation operation force is not sufficient and the burden on the operator is heavy.

An object of the present invention is to solve the above problems and provide a hoisting device for an aerial work vehicle that does not require the hoisting motion of the hoisting device to be performed by inputting.

(Means for Solving the Problems) In order to solve the above problems, the hoisting device for an aerial work vehicle of the present invention has a horizontal maintaining member having a workbench at the end of a boom that can be raised and lowered. The lifting device with a sub jib is mounted on the mounting base provided on the upper part of this horizontal support member so that it can be raised and lowered within the vertical plane and can be fixed at any raised and lowered position by the fixing device. A hoisting device for a local work vehicle, wherein the hoisting device is configured such that the hoisting drive for the mounting base is performed by a single-acting cylinder interposed between the mounting base and the hoisting device. , The main relief valve controls the line pressure to a high pressure state where it is controlled to a pressure slightly higher than the holding pressure of the single acting cylinder due to the weight of the lifting device and a low pressure state where it is released to the tank. And this A check valve installed between the oil supply / exhaust passage and the single cylinder that allows oil to flow into the oil chamber of the single-acting cylinder and prevents backflow, and slightly less than the holding pressure of the single-acting cylinder due to the weight of the lifting device. The pressure oil is configured to be supplied and discharged through an oil passage in which a sub-relief valve that opens at a low pressure and discharges oil from the single-acting cylinder is arranged in parallel.

(Operation) According to the above configuration, in order to raise and lower the hoisting device, the supply base and the oil drainage passage are brought to a high pressure state after the fixing of the mounting base and the hoisting device by the fixing device is released. As a result, the circuit pressure of the oil supply / discharge oil passage is controlled by the main relief valve to a pressure slightly higher than the holding pressure of the single-acting cylinder due to the weight of the lifting device, and is supplied to the single-acting cylinder via the check valve. The single-acting cylinder can be slowly extended to raise and lower the lifting device. Also, in order to lay down the lifting device,
After releasing the fixing of the mounting base and the lifting device by the fixing device, the supply and drain oil passage is set to a low pressure state. As a result, the oil supply / drain passage is released to the tank, so that the holding pressure of the single-acting cylinder is controlled to a pressure slightly lower than the holding pressure of the single-acting cylinder due to the weight of the lifting device. When released into the road, the single-acting cylinder can slowly retract, allowing the hoisting device to collapse.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, a hoisting device A for an aerial work vehicle has a horizontal maintaining member 3 in which a workbench 2 for mounting an operator is swingably attached to the tip of a telescopic boom 1 which can be adjusted up and down. Horizontal axis 4
And a mounting base 4 mounted via a hydraulic cylinder so as to always maintain a horizontal posture regardless of the ups and downs of the telescopic boom 1 and pivotably mounted on the upper end of the horizontal maintaining member 3 about a vertical axis. It is mounted on a horizontal shaft 5 so that it can be adjusted up and down. Reference numeral 6 denotes a main body of the hoisting device A, which is mounted on the upper part of the mounting base 4 by a horizontal shaft 5 so as to be adjustable up and down, and a winch 7 and a sub jib 9 having a sheave 8 at its tip are mounted. Reference numeral 10 denotes a fixing device that locks the locking pin 11 in an arbitrary locking hole 12 and fixes the lifting device A at an arbitrary undulating position. A single-acting cylinder 13 is interposed between the mounting base 4 and the main body 6 of the hoisting device A and drives the hoisting device A up and down.

14 is a hydraulic pump, 15 is the supply of pressure oil from the hydraulic pump 14, and the main relief valve 16 changes the pipeline pressure to the lifting device A.
Is a supply / drain passage for controlling a high pressure state controlled to a pressure slightly higher than the holding pressure of the single acting cylinder 13 due to its own weight and a low pressure state in which the main relief valve 16 is unloaded and released to the tank 17. Reference numeral 18 denotes a check valve that is interposed in an oil passage 19 that connects the oil supply / discharge oil passage 15 and the oil chamber of the single-acting cylinder 13 to allow the oil to flow into the oil chamber of the single-acting cylinder 13 and prevent the reverse flow. Check valve 18
Is a sub-relief valve that is installed in parallel with each other and opens the valve at a pressure slightly lower than the holding pressure of the single-acting cylinder 13 due to the weight of the lifting device A and discharges oil from the oil chamber of the single-acting cylinder 13. Reference numeral 21 is an electromagnetic opening / closing valve which is interposed in the pilot oil passage 22 of the main relief valve 16 and whose opening / closing is controlled by operating the switch 23.
The on-off valve 21 is always in the open position 21a and the main relief valve 16 is unloaded to keep the oil supply and drain passage 13 in a low pressure state.However, if the switch 23 is operated, the on-off valve 21 will be closed.
In addition, the set pressure of the switching main relief valve 16 is controlled to a high pressure state which is controlled to a pressure slightly higher than the holding pressure of the single-acting cylinder 13 due to the weight of the lifting device A. 24 is a hoisting control valve that controls a hoisting cylinder 25 that is connected to the oil supply / drain passage 15 to hoist the telescopic boom 1, and 26 is a telescopic control that controls a telescopic cylinder 27 that is connected to the oil supply / drain passage 15 and that telescopes the telescopic boom 1. The valve 28 is a winch control valve that is connected to the oil supply / drain passage 15 and controls the hoist drive motor 29 of the lifting device A as well. 30
Is a detachable joint interposed in an oil passage 19 for supplying and discharging pressure oil to and from the single-acting cylinder 13.

Next, the operation will be described.

In order to change the hoisting device A from the lying state shown in the solid line in FIG. 1 to the raised state shown in the chain line, first, pull out the locking pin 11 of the fixing device 10 from the locking hole 12 and fix the lifting device A. To cancel. Next, operate the switch 23 to open the open / close valve 21 and open the valve 21b.
And the set pressure of the main relief valve 16 is set to a high pressure state. As a result, the line pressure of the oil supply / drain passage 15 is controlled to a pressure slightly higher than the holding pressure of the single-acting cylinder 13 due to the weight of the lifting device A, so that it is supplied to the single-acting cylinder 13 via the check valve 18. The generated pressure oil slowly extends the single-acting cylinder 13 and raises and lowers the lifting device A. When the lifting device A is raised to a desired position, the locking pin 11 of the fixing device 10 is engaged with the engaging hole 12
It is possible to carry out the hoisting work by suspending the luggage from the tip of the sub jib 9 and fixing it.

In order to bring the hoisting device A to the lying position (shown by the solid line in FIG. 1), the locking pin 11 of the fixing device 10 is pulled out from the locking hole 12 and the hoisting device A is unfixed. At this time, since the switch 23 is off, the open / close valve 21 is in the open position 21b and the main relief valve 16 is unloaded, so that the oil supply / discharge passage 15 is in a low pressure state where it is released to the tank. This allows the single-acting cylinder 13
The holding pressure is released to the oil supply / discharge passage 15 by the sub-relief valve 20 which opens at a pressure slightly lower than the holding pressure of the single-acting cylinder 13 due to the weight of the lifting device A to release the pressure oil. The single-acting cylinder 13 is slowly contracted to cause the lifting device A to fall down. When the lifting device A falls down to a desired position, the locking pin 11 of the fixing device 10 may be inserted into the engagement hole 12 and fixed.

Further, in order to drive the undulating cylinder 25, the telescopic cylinder 27 and the winch 7, after switching the control valves 24, 26 and 28,
If the set pressure of the main relief valve 16 is increased by operating the switch 23, the control valve can be operated and driven as in the conventional case.

In the above description, the embodiment in which the low pressure state of the oil supply / exhaust passage is obtained by unloading the main relief valve has been described, but the unloading control may be performed by the opening / closing valve.

(Effects of the Invention) As described above, according to the present invention, since the hoisting operation of the hoisting device, which was conventionally performed manually, can be hydraulically performed by using the single-acting cylinder, so that work at high places can be performed. This has the effect of improving the operability of the vehicle lifting device.

[Brief description of drawings]

FIG. 1 is an explanatory view showing the structure of a hoisting device for an aerial work vehicle of the present invention, and FIG. 2 is an explanatory view of a hydraulic circuit. Boom …… 1, workbench …… 2 Horizontal maintenance member ………… 3, Mounting base …… 4, Sub jib ………… 9,
Lifting device …… A, single-acting cylinder ………… 13, main relief valve …… 16, oil supply / drain passage …… 15, check valve …… 18, sub relief valve …… 20,

Claims (1)

[Scope of utility model registration request] 1. A hoisting device having a horizontal holding member having a workbench attached to a tip end of a hoisting boom so as to always maintain a horizontal posture, and a sub-jib provided on a mounting base provided on an upper part of the horizontal holding member. Is a hoisting device for an aerial work vehicle, which is mounted so that it can be undulated in a vertical plane and can be fixed to any undulating position by a fixing device, and the hoisting device is a hoisting drive for the hoisting base. A single-acting cylinder interposed between the hoisting device and the hoisting device, and the main-relief valve causes the pipeline pressure to be slightly higher than the holding pressure of the hoisting device due to the weight of the hoisting device. An oil supply / exhaust passage controlled between a high pressure state controlled by pressure and a low pressure state released by a tank, and an oil passage between the oil supply / exhaust passage and the single-acting cylinder, and oil to the oil chamber of the single-acting cylinder. Backflow Pressure oil is supplied by an oil passage in which a check valve for blocking and a sub-relief valve for discharging oil from the single-acting cylinder are opened in parallel to open by a pressure slightly lower than the holding pressure of the single-acting cylinder due to the weight of the lifting device. A hoisting device for an aerial work vehicle characterized by being discharged.