JPH0967094A - Workbench leveling device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a workbench leveling device at low cost, by which follow-up performance of the derricking operation of the workbench with the derricking operation of a boom can be improved, and the workbench is not inclined by the specified angle or more. SOLUTION: A bottom side oil chamber 23a of an upper leveling cylinder 23 and a bottom side oil chamber 22a of a lower leveling cylinder 22 are connected to each other by a bottom side leveling hose 31, and a rod side oil chamber 23b of the upper leveling cylinder 23 and a rod side oil chamber 22b of the lower leveling cylinder 22 are connected to each other by a rod side leveling hose 32. Pilot check valves 41, 42 are provided on both leveling hoses 31, 32, the pilot check valves 41, 42 are opened in the derricking operation of a boom, and respective oil chambers of the upper and lower leveling cylinders 22, 23 are communicated with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a workbench leveling device for maintaining a workbench arranged at the tip of a boom which can be freely moved up and down, at a desired angle regardless of the hoisting angle of the boom.

[0002]

2. Description of the Related Art As a working device having a worktable on which a worker can ride at the tip of a boom that can be freely raised and lowered with respect to a base, there is an aerial work vehicle 10 as shown in FIG. In this aerial work vehicle 10, a boom 13 is erected on a vehicle body 11 and a vertical post 18 which is swingable in the front-rear direction is arranged at the tip of the boom 13. On the other hand, a workbench 14 which can be turned horizontally is provided.

In the aerial work vehicle 10 thus constructed, a work platform leveling device is provided, and the boom 13 is provided.
The workbench 14 is always kept horizontal regardless of the undulation angle. The workbench leveling device includes an upper leveling cylinder 23 arranged between the boom 13 and the vertical post 18, and a lower leveling cylinder 22 arranged between the swivel 12 and the boom 13. . Both of these leveling cylinders 22 and 23 are hydraulic telescopic cylinders.

Then, as shown in FIG. 3, the bottom side oil chambers 22a and 23a of the leveling cylinders 22 and 23 are connected by an oil feed pipe 71 and the rod side oil chambers 22 are connected to each other.
b and 23b are also connected by the oil feed pipe 72, so that the undulating cylinder 2 arranged between the swivel base 12 and the boom 13
When the expansion / contraction operation 1 is performed, the expansion / contraction operation of the upper leveling cylinder 23 is performed according to the expansion / contraction amount of the lower leveling cylinder 22, and the workbench 14 is always kept horizontal.

In the workbench leveling device constructed as described above, the oil supply pipes 71 and 72 are arranged so that the inclination angle of the workbench 14 does not increase when an oil leak occurs and oil leaks. 71 and 72 are provided with pilot check valves 81 and 82.

[0006] Here, after the hoisting operation of the boom 13 is stopped, the work table 14 is swung, the objects are loaded and unloaded on the work table 14, and a winch (not shown) arranged on the work table 14 is used. ), If you do things like
A pressure difference occurs before and after the pilot check valves 81 and 82 (“right and left” in FIG. 3), that is, between the lower leveling cylinder side oil feed pipes 71a and 72a and the upper leveling cylinder side oil feed pipes 71b and 72b. To do.
For example, when lifting is performed by a winch, the pressure in the bottom oil chamber 23a of the upper leveling cylinder 23 and the bottom oil pipe 71b on the upper leveling cylinder side rises.

[0007]

When the boom 13 is laid down in such a state, the lower leveling cylinder 22 is contracted to cause the bottom side oil chamber 2 to move.
The hydraulic oil in 2a flows through the oil feed pipe 71a and is supplied into the bottom side oil chamber 23a.
Since the pilot check valve 81 does not open until the hydraulic pressures before and after 1 become the same (until the pressure inside the oil feeding pipe 71a increases), the extension operation of the upper leveling cylinder 23 is not performed. Therefore, even if the boom 13 falls down, there is a delay in the raising operation (leveling operation) of the workbench 14, which causes the workbench 14 to fall forward at the beginning of the fall operation of the boom.

When the boom 13 is raised, the lower leveling cylinder 22 is extended to increase the pressure in the oil feed pipe 72. As a result, the pilot check valve 81 is opened, but the upper leveling cylinder 23 is contracted until the hydraulic pressures before and after the pilot check valve 81 become the same, so that the work platform 14 vigorously falls down at the beginning of the boom operation. There is also the problem of doing it.

In order to solve the above problem, therefore, as shown in FIG. 4, it is considered to provide a replenishing circuit for replenishing the hydraulic oil to the rod-side oil chambers 22b and 23b of both leveling cylinders 22 and 23. To be This replenishment circuit replenishes the hydraulic oil to the rod-side oil feed pipe 72a on the lower leveling cylinder side of the rod-side oil feed pipe 72 via the pressure reducing valve 91, and to the rod-side oil feed pipe 72 of the replenishment oil feed pipe 73. The pressure in the oil feed pipe 73a on the connected side is equal to the pressure in the oil feed pipe 73b connected to the hydraulic pressure supply source and the pressure reducing valve 91.
When the pressure is smaller than the set pressure of, hydraulic oil is supplied to the oil feed pipe 73a. On the contrary, when the pressure in the oil feed pipe 73a is higher than the set pressure of the pressure reducing valve 91, the oil feed pipe 73a
Supply of hydraulic oil to the machine is cut off.

However, in the refueling circuit configured as described above, the pressure set by the pressure reducing valve 91 is constant, but the pressure difference before and after the pilot check valve 81 is not always constant, so replenishment of the hydraulic oil is performed. There is a problem that the followability cannot be improved due to a shortage, or the workbench 14 is inclined due to excessive supply.
Further, since the pressure reducing valve 91, the check valve 92 and the like are required, there is a problem that the manufacturing cost increases.

The present invention has been made in view of the above problems, and can improve the followability of the hoisting and lowering operation of the workbench accompanying the hoisting and lowering operation of the boom, and the workbench can be tilted by a predetermined angle or more. It is an object of the present invention to provide a workbench leveling device that does not have any cost at a low cost.

[0012]

In order to achieve such an object, a workbench leveling device according to the present invention is arranged so that a swinging operation with respect to a boom can be freely arranged at a tip of a boom which is arranged so as to be raised and lowered. It holds the installed workbench at a desired swing angle, and the upper leveling cylinder installed between the boom and the workbench is used as the amount of expansion and contraction of the lower leveling cylinder that expands and contracts when the boom is raised and lowered. Operate according to the expansion and contraction.

Therefore, the bottom side oil chamber of the upper leveling cylinder and the bottom side oil chamber of the lower leveling cylinder are connected by the bottom side oil passage, and the rod side oil chamber of the upper leveling cylinder and the rod side oil chamber of the lower leveling cylinder are connected. Are connected by the oil passage on the rod side. An opening / closing means is provided on the bottom side oil passage and the rod side oil passage, and the opening / closing means is opened by the opening / closing operation control means when the boom raising / lowering operation means performs the boom raising / lowering operation.

[0014]

When such a workbench leveling device is used, an operation signal is transmitted to the opening / closing operation control means when the boom elevating operation means operates to elevate the boom. Upon receiving the operation signal, the opening / closing operation control means opens the opening / closing means so that the oil chambers of the upper and lower leveling cylinders communicate with each other. The actuation signal here means a hydraulic signal or an electric signal.

As a result, the pressure in each oil passage can be made uniform at all times, and the working oil between both leveling cylinders can be quickly supplied and discharged. For this reason, the expansion / contraction operation of the upper leveling cylinder according to the expansion / contraction operation of the lower leveling cylinder is made to follow, and the swinging operation in the vertical plane of the workbench is quickly performed.

Further, since the opening / closing means is closed when the boom operating means is not operating, even if the hydraulic oil leaks in the bottom side oil passage or the rod side oil passage, the operation in the upper leveling cylinder is performed. Oil is not supplied or discharged, and the worktable tilt angle does not increase.

A workbench angle detecting means for detecting the tilt angle of the workbench is provided, and when the workbench angle detecting means detects a tilt angle equal to or more than a predetermined angle, how to operate the boom hoisting operation means. Regardless, it is preferable that the opening / closing operation control means performs the closing operation of the opening / closing means.

According to the workbench leveling device having such a structure, the workbench does not tilt more than a predetermined angle even if a leak occurs from the oil passage when the boom is raised. It's safe.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An aerial work vehicle 10 provided with a work table leveling device according to the present invention will be described below with reference to FIGS. The aerial work vehicle 10 has a swivel base 12 on the vehicle body 11 that can be swiveled with respect to the vehicle body 11 by the rotation operation of a hydraulic motor (not shown). . The telescopic boom 13 is telescopically (nested) telescopically adjustable base boom 13a, intermediate boom 13b, and tip boom 1.
3 c, the base end boom 13 a is pivotally supported by the swivel base 12 so that it can be raised and lowered.

This telescopic boom 13 is telescopically extended by the telescopic operation of a boom telescopic cylinder (not shown) provided inside the telescopic boom 13, and the telescopic cylinder 21 provided between the swivel base 12 and the base end boom 13a is telescopically extended. Elevation is activated by operation. Further, jacks 25 for stably supporting the vehicle body 11 when the telescopic boom 13 is operated are provided at four positions on the front, rear, left and right of the vehicle body 11,
25 is provided, and these jacks 25, 25 also perform expansion / contraction operation (grounding / storing operation) by expansion / contraction operation of a built-in jack expansion / contraction cylinder (not shown).

A support member 15 is attached to the tip of the tip boom 13c so as to be vertically swingable (in a vertical plane).
The support member 15 has a vertical post 18 extending upward, and a work platform 14 configured to allow an operator to board is horizontally pivotably attached to the vertical post 18.

Since an operator rides on the workbench 14, the workbench 14 must always be held horizontally regardless of the ups and downs of the telescopic boom 13. Therefore, this aerial work vehicle 1
A workbench leveling device having a lower leveling cylinder 22 and an upper leveling cylinder 23 is attached to 0. The lower leveling cylinder 22 is arranged between the swivel base 12 and the base end boom 13a, and the upper leveling cylinder 23 is arranged between the tip boom 13c and the support member 15. The details of this work table leveling device will be described later.

The undulating cylinder 21, the lower leveling cylinder 22 and the upper leveling cylinder 23 are respectively provided in the bottom side oil chambers 21a to 23a and the rod side oil chambers 21b to 23b.
Is a hydraulic expansion / contraction cylinder configured to perform expansion / contraction operation by controlling supply / discharge of hydraulic oil to / from the bottom side oil chamber and the rod side oil chamber. The boom telescopic cylinder and the jack telescopic cylinder are hydraulic telescopic cylinders configured similarly to the cylinders 21 and the like described above.

The hoisting cylinder 21 and the boom telescopic cylinder are expanded and contracted by controlling the supply and discharge of hydraulic oil by the boom control valve 17a connected to the pump P and the tank T. The jack telescopic cylinder is also telescopically operated by controlling the supply and discharge of hydraulic oil by the jack control valve 17b which is also connected to the pump P and the tank T.

The supply of hydraulic oil to the control valves 17a and 17b is performed by supply pipes 62 and 63 branched from the supply pipe 61 connected to the pump P. Here, the unload control valves 52 and 53 are provided in the supply pipes 62 and 63, respectively.
Is provided to prevent the hydraulic oil from flowing into the pump P from the valve side. When the control valves 17a and 17b are not operating, the unload control valve 52,
From the pump P via 53, the respective control valves 17a, 17b
The hydraulic oil supplied to the tank is returned to the tank T through the return pipes 66 and 67.

In the aerial work vehicle 10 thus constructed, the control valves 17a and 17b are operated by controlling the operation of the operating devices 17 and 17 arranged on the workbench body 14a and the vehicle body 11. By controlling the supply and discharge of the hydraulic oil to and from each cylinder, the telescopic boom 13 is raised and retracted, the swivel base 12 is swung, and the jack 25 is used.
Performs expansion and contraction operation.

For example, the telescopic boom 1 is operated by the operating device 17.
When the telescopic operation of No. 3 is performed, the boom control valve 17a is actuated by the operation signal from the operating device 17, the hydraulic oil is supplied to and discharged from the telescopic cylinder, and the telescopic boom 13 is telescopically operated. Further, when the jacks 25, 25 are expanded and contracted by the operation device 17, the jack control valve 17b is operated by an operation signal from the operation device 17, and hydraulic oil is supplied to and discharged from the jack expansion and contraction cylinder.

When the telescopic boom 13 is hoisted up and down by the operating device 17, the boom control valve 17a is operated by an operating signal from the operating device 17, supplied from the pump P and discharged to the tank T. Hydraulic oil is applied to the bottom side oil chamber 21a of the undulating cylinder 21 and the rod side oil chamber 2
By supplying / discharging to / from 1b, the hoisting cylinder 21 is extended / contracted, and the telescopic boom 13 is raised / lowered.

As described above, when the telescopic boom 13 is raised and lowered, the workbench leveling device is operated so that the workbench 14 is substantially horizontal. Here, the work table leveling device will be described. In the upper and lower leveling cylinders 22 and 23, the bottom-side oil chambers 22a and 23a are connected to each other by a bottom-side leveling hose (bottom-side oil passage) 31, and the rod-side oil chamber 22b and
The rods 23b are connected by a rod-side leveling hose (rod-side oil passage) 32.

Each leveling hose 31, 32 has a pilot check valve (opening / closing) which allows only the flow of hydraulic oil from the lower leveling cylinder 22 to the upper leveling cylinder 23 when the closing operation is performed (when pilot pressure is not applied). Means) 41, 42 are provided. As a result, even if the hydraulic oil leaks in any of the leveling hoses 31 and 32, the upper leveling cylinder 23 does not expand and contract, so that the workbench 14 does not tilt.

The pilot pressure is supplied to the pilot check valves 41 and 42 by a pilot oil passage branched from the supply pipe 62. The pilot oil passage is composed of a pump side oil passage 64 and a pilot check valve side oil passage 65, and a solenoid valve (opening / closing operation control means) 51 is arranged between the oil passages 64 and 65. The solenoid valve 51 connects the pump-side oil passage 64 and the pilot check valve-side oil passage 65 in the excited state, and the pump-side oil passage 6 in the non-excited state.
4 and the pilot check valve side oil passage 65 are shut off (the state shown in FIG. 2).

When each operation of the boom 13 is performed, the switch 52 is turned on to excite the solenoid 51a so that the pump side oil passage 64 and the pilot check valve side oil passage 65 are in communication with each other. When the operation device 17 controls the operation of one of the booms 13 (not limited to the hoisting operation) and the boom control valve 17a controls the supply / discharge of the hydraulic oil, the return of the hydraulic oil from the return pipe 66 is performed. Is cut off, and hydraulic oil is supplied to the pilot oil passages 64 and 65 (transmission of an operation signal).

As a result, the pilot check valve 4
1, 42 perform an opening operation, and the oil chambers 22a, 23a and 22b, 23b communicate with each other. Therefore, the telescopic boom 1
3 is performed (elevating operation of the undulating cylinder 21), the rod 22c of the lower leveling cylinder 22 is pulled, so that the hydraulic oil is discharged from the rod-side oil chamber 22b of the lower leveling cylinder 22. The oil is supplied to the rod side oil chamber 23b of the upper leveling cylinder 23, and the working oil discharged from the bottom side oil chamber 23a of the upper leveling cylinder 23 is the lower leveling cylinder 2
The upper leveling cylinder 23 is contracted by being supplied to the second rod-side oil chamber 22a.

When the retractable operation of the telescopic boom 13 (reduction operation of the hoisting cylinder 21) is performed, the hydraulic oil is supplied and discharged in the opposite manner to the above, and the upper leveling cylinder 23 is extended. As a result, a swinging motion opposite to the undulating motion is applied to the support member 15, so that the vertical post 18
Oscillates with respect to the telescopic boom 13 in a vertical plane to maintain a vertical state at all times, and the posture of the workbench 14 is always kept horizontal.

During the expansion and contraction operation of these upper leveling cylinders 22, the respective leveling hoses 3 are
Since the pressures in 1 and 32 are uniform, the hydraulic oil is smoothly supplied and discharged according to the expansion and contraction operation of the lower leveling cylinder 22, and the operation delay of the upper leveling cylinder 22 and the rapid expansion and contraction operation are performed. There is no.

Next, the case where the hydraulic oil leaks from the leveling hoses 31 and 32 will be described. When the worker finds this leak, the operation oil is stopped from being supplied to the pilot oil passage by stopping the operation of the operation device 17. Therefore, the pilot check valve 4
1, 42 are closed, the expansion and contraction of the upper leveling cylinder 23 is stopped, and the inclination angle of the workbench 14 does not increase.

If the worker cannot find the leak, the workbench 14 is inclined from the horizontal state. Therefore, in this work platform leveling device, a tilt sensor 16 for detecting the tilt angle of the work table 14 is provided, and when the tilt angle becomes equal to or greater than the predetermined tilt angle θ, the expansion / contraction operation of the upper leveling cylinder 23 is performed. Is to be stopped.

The tilt sensor 16 is arranged on the workbench 14 and sends a detection signal when the swing angle in the vertical plane of the workbench 14 becomes a predetermined tilt angle θ or more from the horizontal direction to the vertical direction. Then, the switch 52 is turned off. As a result, the solenoid 51a is de-energized, the solenoid valve 51 moves to the right, the pump-side oil passage 64 and the pilot check valve-side oil passage 65 are shut off, and the pilot check valves 41, 42 are closed.

Therefore, even if the telescopic boom 13 is contracted or collapsed to store the workbench 14, the hydraulic oil is not supplied to the pilot oil passages 64 and 65, so that the upper leveling cylinder 23 is not supplied. The expansion and contraction of is not performed. Therefore, it is possible to maintain the inclination angle of the workbench 14 with respect to the boom 13 in the state where the tilt sensor 16 transmits the detection signal, and to secure the safety of the worker or the load on the workbench 14. it can.

Here, the predetermined inclination angle θ is preferably set to about 6 °. In addition, the inclination angle of the workbench 14 is 6 °
In order to prevent the tilt angle from increasing (tilting up to 6 °) during the retracting operation of the telescopic boom 13 if the operation of the operating device 17 is stopped before the leakage of hydraulic oil is detected before reaching 0 ° A switch for turning off the switch 52 may be provided separately from the switch 16.

Further, in the above embodiment, the boom 1
3 has a structure in which undulation / extension / contraction / swing operation can be freely performed, and when any one of these operations is controlled by the operating device 17, the pilot check valve 41,
Although the opening operation of 42 is performed, the present invention is not limited to this. For example, the boom 13 may be constructed so that it can be at least raised and lowered.
The operation control of the operating device 17 for performing the opening operation of the pilot check valves 41 and 42 may be the undulating operation.

Further, in the above embodiment, the pilot check valves 41 and 42 are used as the opening / closing means, but a solenoid valve or the like for opening / closing may be used. In this case, it is detected that the operating device 17 has been operated, that the boom control valve 17a has been operated, or that the hoisting cylinder 21 has been expanded / contracted, and the solenoid valve is opened. It should be made possible. As is apparent from this, the boom operating means described in the claims includes the operating device 17, the boom control valve 17a, the hoisting cylinder 21, and the like. Further, the tilt sensor 16 allows the workbench 14 to operate.
When it is detected that is tilted by a predetermined angle or more, the solenoid valve may be closed.

In the above embodiment, the pump P
The unloading control valves 52 and 53 are arranged at the branch portions from the supply pipes 62 and 63 to the supplying pipes 62 and 63. Instead of the unloading control valves 52 and 53, either of the supplying pipes 62 and 63 is supplied. A solenoid valve may be used that selectively supplies hydraulic oil to the.

Further, in the above embodiment, the workbench 1
The case where the workbench leveling device is used to keep the worktable 4 always horizontal has been described, but the workbench 14 may of course be kept at a desired angle other than horizontal.

In the above embodiment, the boom 1
Although the aerial work vehicle 10 in which the base on which 3 is disposed is configured by a freely movable vehicle body has been described as an example, it is needless to say that the base is not limited to the vehicle body.

[0046]

As described above, according to the work table leveling device of the present invention, since the oil passages connecting the upper and lower leveling cylinders communicate with each other when the boom is operating, the boom hoisting operation can be quickly followed. Since the work platform is hoisted and lifted, the work platform tilt angle can be maintained constant regardless of the boom hoist angle. For this reason, a hydraulic oil supply circuit for improving the followability of the undulating operation of the workbench is not required, so that the manufacturing cost of the leveling device can be reduced and the upper leveling cylinder can be always expanded and contracted with an appropriate expansion / contraction amount. The workbench can be extended and retracted so that the workbench is not tilted too much.

Even if an oil leak occurs in the oil passage connecting the upper and lower leveling cylinders, the operation of the operating device may be stopped to prevent the upper leveling cylinder from expanding and contracting. Therefore, it is possible to prevent the inclination angle of the workbench from increasing. Furthermore, the inclination sensor prevents the inclination angle of the workbench from exceeding a predetermined angle, and even when the boom is operated,
It is safe because the tilt angle of the workbench with respect to the boom can be maintained when the tilt sensor operates.

[Brief description of drawings]

FIG. 1 is a front view showing an aerial work vehicle equipped with a work table leveling device according to the present invention.

FIG. 2 is a hydraulic and electric circuit diagram showing the configuration of the work table leveling device.

FIG. 3 is a hydraulic circuit diagram showing a configuration of a conventional workbench leveling device.

FIG. 4 is a hydraulic circuit diagram showing a configuration of a conventional workbench leveling device.

[Explanation of symbols]

 10 High-altitude work vehicle 11 Vehicle body 12 Revolving platform 13 Telescopic boom 14 Work platform 16 Tilt sensor 17 Operating device 21 Elevating cylinder 22 Lower leveling cylinder 23 Upper leveling cylinder

Claims (2)

[Claims] 1. A boom having at least a hoisting motion provided on a base, a work table having a tip end of the boom freely swingable in a vertical plane, the boom and the work. An upper leveling cylinder, which is disposed between the work table and the work table to perform a rocking operation in a vertical plane of the work table, and a lower leveling cylinder which performs a work operation according to the hoisting operation of the boom. A boom operating means for performing at least a hoisting operation of the boom; a bottom side oil passage connecting a bottom side oil chamber of the upper leveling cylinder and a bottom side oil chamber of the lower leveling cylinder; and a rod side of the upper leveling cylinder. The rod-side oil passage that connects the oil chamber and the rod-side oil chamber of the lower leveling cylinder, and the bottom-side oil passage and the rod-side oil passage are configured to be openable and closable. And an opening / closing means for communicating the bottom side oil chambers and the rod side oil chambers with each other, and an opening / closing operation control means for performing an opening operation of the opening / closing means based on an operation signal from the boom operating means. Characteristic workbench leveling device. 2. A workbench angle detection means for detecting a tilt angle of the workbench is provided, and when the workbench angle detection means detects a tilt angle equal to or larger than a predetermined angle, the boom operation means is operated. 2. The workbench leveling device according to claim 1, wherein the opening / closing operation control means closes the opening / closing means based on a detection signal of the workbench angle detecting means.