JP2003252587A - Working equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working equipment preventing a working table from exceeding a movable range when a boom hoisting angle is small and imposing no working restriction of the boom. <P>SOLUTION: This working equipment 20 is provided with the boom 21 pivotally connected to a turning table 9 so as to freely hoist, first and second expansion/contraction cylinders 29 and 31 disposed in the boom 21 with their coaxially connected thereto and expanding/contracting the boom 21, and a hoisting cylinder 27 hoisting the boom 21. The boom 21 is constituted by telescopically assembling a base end boom 22, an intermediate boom 23, and a tip boom 24. The tip portion of a rod 31d<SB>1</SB>of the second expansion/contraction cylinder 31 is pivotally connected to the base side inside of the base end boom 22, and the tip portion of a cylinder tube 29c of the first expansion/contraction cylinder 29 is pivotally connected to the base part of the intermediate boom 23 via a connecting case 35. The second expansion/contraction cylinder 31 is driven by operating fluid delivered from the hoisting cylinder 27 and the first expansion/contraction cylinder 29 is driven separately from the hoisting cylinder 27. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a working device,
More specifically, the present invention relates to a work device including a boom configured to move up and down and extend and retract in a vehicle body, an up and down cylinder that moves up and down the boom, and a retractable cylinder that extends and retracts the boom.

[0002]

2. Description of the Related Art Such a working device is often constructed by having a work table at the tip of a boom, and is generally mounted and used in a work vehicle for working in high places. Such an aerial work vehicle is generally one in which a work table is moved to a desired high position by using a boom, and an aerial work is performed by a worker who is on the work table. When the vehicle is moved to a high place, the overturning moment acting on the vehicle body increases and the vehicle body support is likely to become unstable. For this reason, it has been generally practiced in the past to equip a work vehicle for high places with a fall prevention device that prevents the moment in the fall direction from becoming excessively large.

This fall prevention device has a preset reference value for the fall direction moment that changes with the operation of the boom (hereinafter, this reference value is referred to as "allowable fall moment").
It is configured to regulate the operation so that it exceeds the allowable range, and specifically, it detects the moment in the falling direction acting on the vehicle and restricts the operation of the boom so that it exceeds the allowable falling moment, or the moment in the falling direction is allowed. The movable range of the work table that can move without exceeding the tipping moment is set in advance, and the operation of the boom is controlled so that the work table exceeds the movable range.

[0004]

The movable range is set to a range in which the working radius is substantially constant regardless of the boom hoisting angle. Therefore, when the boom hoisting angle is large, the boom is extended. The amount may be increased. However, if the boom hoisting angle is small, tilting the boom while keeping the boom extension amount large may cause the work platform to move beyond the movable range. The problem of having to do

The present invention has been made in view of the above problems, and when the hoisting angle of the boom is small, the workbench does not exceed the movable range and the boom operation need not be restricted. An object of the present invention is to provide a working device having such a configuration.

[0006]

In order to solve the above-mentioned problems, a working apparatus according to the present invention is provided on a base (for example, a swivel base 9 in the embodiment) so as to be movable up and down, and a first boom (for example, a boom). The base boom 22 in the embodiment and the second boom (for example, the intermediate boom 23 in the embodiment).
The telescopic boom that is telescopically combined with the boom, the hoisting cylinder that hoists the boom with respect to the base, and the boom that is connected within the boom are connected to each other. A first telescopic cylinder and a second telescopic cylinder to be moved, and one of the first telescopic cylinder and the second telescopic cylinder in the connected state is connected to the first boom, the other is connected to the second boom, and the second telescopic cylinder Is configured to expand and contract in response to the supply of hydraulic oil discharged from the undulating cylinder, to extend when the boom is raised and lowered by the undulating cylinder, and to contract when the boom is laid down by the undulating cylinder. The cylinder is configured to extend and contract independently of the undulating cylinder.

According to the working apparatus having the above-described structure, the second telescopic cylinder for expanding and contracting the boom is constructed to expand and contract in conjunction with the hoisting cylinder, so that the workbench can be moved from the low position to the high position. When the hoisting cylinder is actuated to raise and lower the boom in order to move the second hoisting cylinder, as the hoisting angle of the boom increases, the second telescopic cylinder expands and the boom expands. Therefore, in the work apparatus according to the present invention, the extension amount of the boom at the upper position can be increased as compared with the boom provided with only the first telescopic cylinder. In addition, when the work platform is moving to a high position and the boom is laid down to lower the work platform to the ground, the undulation cylinder operates so that the boom lays down. Then, the second telescopic cylinder is contracted to reduce the extension amount of the boom. For this reason, in a region where the hoisting angle of the boom is small, the work platform can be moved within the movable range without restricting the operation of the boom. As a result, for example, if the boom is tilted from the state where the work platform is located near the limit line in the allowable movement range where there is no risk of the vehicle tipping over when the boom is fully extended, the boom will fall over. However, since the work table is contracted, the workbench can be moved inward of the limit line even in a region where the boom undulation angle is small. For this reason, even when the work range restricting device that restricts the operation of the boom exceeding the allowable movement range is mounted on the vehicle, the work table can be moved from the high position to the low position in a non-stop manner.

In the working apparatus having the above construction, either one of the first telescopic cylinder and the second telescopic cylinder is allowed to project into and move into the other cylinder tube of the first telescopic cylinder and the second telescopic cylinder. The first telescopic cylinder or the second telescopic cylinder disposed inside, the base end portion of the cylinder tube to the distal end portion of the piston of the first telescopic cylinder or the second telescopic cylinder disposed outside. The connection may be made so that the first telescopic cylinder and the second telescopic cylinder are located on the coaxial line.

According to the working apparatus having the above-mentioned structure, the cylinder tube of one of the first telescopic cylinder and the second telescopic cylinder is projected into and inserted into the other cylinder tube of the first telescopic cylinder and the second telescopic cylinder. By arranging as much as possible, it is possible to dispose the two telescopic cylinders in the boom even in the fully contracted boom having a short length.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to FIGS. The present embodiment shows a mode of a self-propelled aerial work vehicle equipped with a work platform at the tip of a boom configured to be extendable and retractable.

[0011]

[First Embodiment] First, before explaining a working apparatus according to a first embodiment of the present invention, an aerial work vehicle equipped with the working apparatus will be described. As shown in FIG. 1, the aerial work vehicle 1 has a pair of front wheels 5 and rear wheels 7 on the front and rear sides of the vehicle body 3, and the front wheels 5 are configured to be rotatable and steerable.
The rear wheel 7 is a drive wheel and is configured to be rotationally drivable.

At the center of the vehicle body 3, there is a swivel base 9 which can swivel freely.
Is provided, and the swivel base 11 is configured to be swivelable by a swivel motor 11 disposed on the vehicle body 3. A balancer weight 13 that holds the balance of the vehicle is attached to the bottom of the swivel base 9 on the front end side. A working device 20 is provided above the swivel base 9 of the aerial work vehicle 1 configured as described above.

The working device 20 has a base 21 pivotally connected to a swivel base 9, and a boom 21 which can be swung up and down, a hoisting cylinder 27 for hoisting the boom 21 with respect to the swivel 9, and a boom 21 shown in FIG. A first telescopic cylinder 29 and a second telescopic cylinder 29, which are provided in a state where they are connected to each other on a coaxial line to extend and retract the boom 21.
The telescopic cylinder 31 is included. Boom 2
1 is a base boom 22, a middle boom 23, and a tip boom 2
It is constructed by combining 4 in a nested manner. As shown in FIG. 2, the tip portion of the rod 29d1 of the piston 29d built in the first telescopic cylinder 29 has the second telescopic cylinder 3
The first telescopic cylinder 29 and the second telescopic cylinder 31 are connected to the base end of the first cylinder tube 31c and are coaxially connected. The tip portion of the rod 31d1 of the piston 31d built in the second telescopic cylinder 31 is pivotally connected to the side wall 22a on the base end side of the base boom 22, and is attached to the outer surface on the tip side of the cylinder tube 29c of the first telescopic cylinder 29. A cylindrical connection case 35 that surrounds this is attached. The connecting case 35 extends to the rod-side tip of the second telescopic cylinder 31 so as to surround the second telescopic cylinder 31,
The tip of the connecting case 35 is pivotally connected to the inside of the side wall 23 a on the base end side of the intermediate boom 23. Therefore, when the first telescopic cylinder 29 expands and contracts, the intermediate boom 23 can expand and contract with respect to the base boom 22 through the connecting case 35. A rotation roller that rotates in contact with the inner surface of the tip boom 24 at the base end of the cylinder tube 29c of the first telescopic cylinder 29 and guides relative movement of the first telescopic cylinder 29 and the second telescopic cylinder 31 with respect to the boom 21. 37 is provided. The tip boom 24 is configured to extend and contract in conjunction with the intermediate boom 23 by means of a wire (not shown) that is bridged with the intermediate boom 23. Therefore, when the first telescopic cylinder 29 expands and contracts, the entire boom 21 expands and contracts.

As described above, the first unit built in the boom 21
As shown in FIG. 3, the telescopic cylinder 29 and the second telescopic cylinder 31 are arranged in the hydraulic circuit 40, and their operations are controlled by the first operation control valve 41 and the second operation control valve 43. More specifically, the hydraulic pump P is connected to the first operation control valve 41 and the second operation control valve 43 via the pump pressure oil passage 45, and the second operation control valve 43 and the undulating cylinder 27.
The bottom chambers 27a of No. 2 are connected via the first oil passage 47, and the rod chamber 27b of the undulating cylinder 27 and the second telescopic cylinder 3 are connected.
The bottom chambers 31a of No. 1 are connected via the second oil passage 49,
The rod chamber 31b of the second telescopic cylinder 31 and the second operation control valve 43 are connected via the third oil passage 51. Also,
The bottom chamber 29a of the first telescopic cylinder 29 and the first operation control valve 41 are connected via a fourth oil passage 53, and the rod chamber 29b of the first telescopic cylinder 29 and the first operation control valve 41 are connected to a fifth oil passage. It is connected through 55. First operation control valve 41
An oil discharge passage 57 is connected to the second operation control valve 43, and the first operation control valve 41 and the second operation control valve 43 communicate with the tank T via the oil discharge passage 57.

First operation control valve 41 and second operation control valve 4
Reference numeral 3 is a 4-port 3-position electromagnetic directional control valve. The first operation control valve 41 is in the neutral state, and the fourth oil passage 53 and the fifth oil passage 5
5 is shut off and the spool (not shown) built in the first operation control valve 41 moves to one side, the fourth oil passage 53 and the pump pressure oil passage 45 communicate with each other, and the fifth oil passage 55 When the spool (not shown) moves to the other side, the pump pressure oil passage 45 and the fifth oil passage 55 communicate with each other, and the fourth oil passage 53 and the discharge oil passage 57 communicate with each other. Are configured to communicate with each other. On the other hand, the second operation control valve 43
Shuts off the first oil passage 47 and the third oil passage 51 in the neutral state,
Spool built in the first operation control valve 41 (not shown)
Moves to one side, the first oil passage 47 and the pump pressure oil passage 4
5 communicates with the third oil passage 51 and the discharge oil passage 57.
And the spool (not shown) moves to the other side, the pump pressure oil passage 45 and the third oil passage 51 communicate with each other, and the first oil passage 47 and the discharge oil passage 57 communicate with each other. Has been done. Therefore, the second telescopic cylinder 31 operates in conjunction with the hoisting cylinder 27, and if the hoisting cylinder 27 is extended by the supply / discharge control of hydraulic oil from the second operation control valve 43, the second telescopic cylinder 31 is also extended. Then, if the undulating cylinder 27 contracts, the second telescopic cylinder 31 also contracts. Further, the first telescopic cylinder 29 has the first operation control valve 41.
It is driven independently of the undulating cylinder 27 by the control of the supply and discharge of hydraulic oil from.

As shown in FIG. 1, a work table 70, which is swingable up and down and is supported in a horizontal state regardless of the hoisting angle of the boom 21, is provided at the tip of the boom 21 having the above-described structure. It is installed. The work platform 70 includes a boom operating device (not shown) for operating the hoisting motion and extension motion of the boom 21, and a swiveling motion of the swivel base 9, and a driving operation device (not shown) for steering the front wheels 5 and driving the rear wheels 7. It is provided.

Next, the working device 20 configured as described above.
The operation of will be described with reference to FIG. Note that FIG. 4 shows a movement range in which the workbench 70 moves when the vehicle is viewed from the side, and in the figure, a solid line connecting points A, B, C and D acts on the vehicle. A limit line L0 of a movable range H (a shaded area) in which the workbench 70 can move without the overturning direction moment exceeding the allowable overturning moment is shown, and a solid line and a one-dot chain line connecting the points A, B and E. The line L1 indicated by indicates the trajectory of the workbench 70 when the boom 21 is tilted down with the extension amount of the boom 21 being the same while the workbench 70 is positioned at the point A. The working apparatus 20 shown in FIG. 2 is configured so that the tip end portion of the workbench 70 comes to the point A on the limit line L0 when the undulating cylinder 27 and the first telescopic cylinder 29 extend and move to the stroke ends. Set to be present.

First, the case where the boom 21 is raised and lowered from the state where the boom 21 is in the fully contracted state and the workbench 70 is at the point K at the low position will be described. When a boom operating device (not shown) is operated so that the boom 21 is raised and lowered by an operator (not shown) who is on the workbench 70 from the state where the workbench 70 is at the point K at the low position, FIG. As shown in FIG. 6, the hydraulic oil discharged from the hydraulic pump P flows into the bottom chamber 27 a of the undulating cylinder 27 via the second operation control valve 43 and the first oil passage 47, and the piston 2 of the undulating cylinder 27
Hydraulic pressure acts on the surface of the bottom chamber 27a side of 7d. This hydraulic pressure is transmitted to the bottom chamber 31a of the second telescopic cylinder 31 via the second oil passage 49, and acts in the direction in which the piston 31d of the second telescopic cylinder 31 extends. On the other hand, the second operation control valve 43 keeps the third oil passage 51 in communication with the discharge oil passage 57, and the working oil in the rod chamber 31b of the second telescopic cylinder 31 is in the third oil passage 51 and the second operation control. It is in a state where it can flow out to the discharge oil passage 57 via the valve 43. Therefore, the second
When the piston 31d of the telescopic cylinder 31 is acted on by a hydraulic pressure in a direction in which the piston 31d extends, the hydraulic oil in the rod chamber 31b flows out through the third oil passage 51. As a result, the undulating cylinder 27 extends and the second telescopic cylinder 31 also extends.

When the hoisting cylinder 27 and the second telescopic cylinder 31 are simultaneously extended in this manner, as shown in FIG. 2, the boom 21 is hoisted around the pivotal position 71 of the boom 21 and the swivel base 9 as the swing center. While being swung up, the cylinder tube 31c of the second telescopic cylinder 31 moves the piston 31d.
Move away from the boom to the tip of the boom. Therefore, the first telescopic cylinder 29 moves to the boom tip side, and the intermediate boom 23 moves to the base boom 22 via the connecting case 35.
It stretches against. At the same time, the tip boom 24 extends with respect to the intermediate boom 23. As a result, the entire boom extends, and as shown in FIG. 4, the boom length gradually increases as the boom 21 moves up and down, and the workbench 70 at the point K moves to the point K ′. Therefore, the second telescopic cylinder 31 is not provided in the boom 21, and the boom 2
Compared with the case where the total extension amount of 1 is raised and lifted while R, the extension amount of the boom 21 can be made longer in the upper position, and the workbench 70 can be moved to a higher position.

Next, the case where the workbench 70 is moved from the state where the workbench 70 is at the high position of the point A to the low position A'is described. Note that when the workbench 70 is moving to the position of the point A, the undulating cylinder 27 and the first telescopic cylinder 29 shown in FIG. 3 are in a state of extending to the stroke end, as described above. First, the workbench 70 shown in FIG.
A boom operating device (not shown) is operated so that the boom 21 falls down by an operator (not shown) who is on board. When the boom operation device is operated, as shown in FIG.
The operation control valve 43 connects the first oil passage 47 to the discharge oil passage 57 and the third oil passage 51 to the pump pressure oil passage 45. As a result, the weight of the workbench 70 and the operating hydraulic pressure from the hydraulic pump P act on the rod-side surface of the piston 31d of the second telescopic cylinder 31 via the third oil passage 51, and this hydraulic pressure is the second hydraulic pressure.
It acts on the piston 27 d of the undulating cylinder 27 via the oil passage 49. Here, since the first oil passage 47 is in communication with the discharge oil passage 57, if the hydraulic pressure in the direction of contracting the undulating cylinder 27 acts on the undulating cylinder 27, the operation in the bottom chamber 27a of the undulating cylinder 27 is performed. The oil flows through the first oil passage 47 and the discharge oil passage 57 and is returned to the tank T. For this reason, the hoisting cylinder 27 contracts and the second telescopic cylinder 31 contracts, and as shown in FIG. 4, the boom 21 falls down while the overall length R gradually decreases, and the workbench 70 moves to the point A. To a point A ', which is a low position, by moving on a line L2 indicated by a solid line.

Now, consider a case where the boom 21 is tilted while keeping the working radius R of the boom 21 as it is while the workbench 70 is located at the point A. In this case, when the workbench 70 moves to a position lower than the point B, the workbench 70 exceeds the limit line L0 of the movable range H, increasing the risk of the vehicle tipping over.

However, in the working device 20 according to the present invention shown in FIG. 2, since the second telescopic cylinder 31 is configured to be contracted when the boom 21 falls down as described above, it is shown in FIG. Thus, the working radius R of the boom 21 becomes smaller as the hoisting angle of the boom 21 becomes smaller. Therefore, the workbench 70 moves inward inward of the limit line L0 as the boom 21 falls. As a result, the workbench 70 always moves within the movable range H, the position of the workbench 70 is detected, and the operation of the boom 21 in which the detected position of the workbench 70 exceeds the movable range H is detected. Even when a so-called work range restricting device for restricting is mounted on the vehicle, the workbench 70 can be moved from the high position to the low position in a non-stop manner. Further, in the case where the work device 20 is configured such that the work table 70 comes to the point A in a state where the boom 21 is fully extended, the boom 2 does not need to be equipped with a work range restricting device.
The operation of 1 does not increase the risk of the vehicle falling. Therefore, the cost of the vehicle can be reduced.

The connecting direction of the first telescopic cylinder 29 and the second telescopic cylinder 31 shown in FIG. 2 is not limited to the one described above, but as shown in FIG.
1 is reversed and the rod 3 of the second telescopic cylinder 31
The tip of 2d1 is connected to the rod 29d of the first telescopic cylinder 29.
These may be built in the boom 21 shown in FIG. 2 so as to be connected to the tip portion of 1. In this case, the base end portion of the cylinder tube 31c of the second telescopic cylinder 31 is pivotally connected to the inner surface on the base end side of the base end boom 22 shown in FIG. 2, and the second oil passage 49 is connected to the bottom of the second telescopic cylinder 31. Connect to room 31a,
The third oil passage 51 is connected to the rod chamber 31b of the second telescopic cylinder 31.
Connect to. Further, in the state shown in FIG. 2, the first telescopic cylinder 29 and the second telescopic cylinder 31 may be replaced with each other.

Further, as shown in FIG. 4, when the workbench 70 is moved along the moving line L2 while the boom 21 is fully extended, the workbench 70 can move within a movable range H.
Will move inside. For this reason, the movable range of the workbench 70 is narrower than the movable range H, and the working range is narrower than the case where the workbench 70 is movable within the movable range H. Therefore, as shown in FIG.
The workbench 70 passes through a point B which is an intermediate point of the limit line L0, and the moving line L3 near the limit line L0.
When the first telescopic cylinder 29 and the second telescopic cylinder 31 shown in FIG. 2 having a stroke that allows the work table 70 to pass through are prepared, the work table 70 when the work table 70 passes near the limit line L0. The work range of can be expanded.

In the above-described embodiment, an example in which the first telescopic cylinder 29 and the second telescopic cylinder 31 are connected on the coaxial line has been shown, but as shown in FIGS. 7 (a) and 7 (b). , First telescopic cylinder 29 and second telescopic cylinder 3
1 in the vertical direction, both cylinder tubes 29c,
You may arrange | position in the boom 21 shown in FIG. 2 in the state which 31c was connected. 7A shows an example in which the rod side ends of the first telescopic cylinder 29 and the second telescopic cylinder 31 are arranged in the same direction, and FIG. 7B shows the first telescopic cylinder 2
9 shows an example in which the rod-side end portions of the ninth and second telescopic cylinders 31 are arranged in opposite directions. In the case shown in FIG. 7A, the tip end portion of the rod 31d1 of the second telescopic cylinder 31 is pivotally connected to the base portion of the base end boom 21 shown in FIG. It is pivotally connected to the base of the intermediate boom 23 shown in FIG. In the case shown in FIG. 7 (3), the distal end of the rod 31d1 of the second telescopic cylinder 31 is pivotally connected to the base of the proximal boom 21 shown in FIG. 2, and the base end of the cylinder tube 29c of the first telescopic cylinder 29 is connected. Is pivotally connected to the base of the intermediate boom 23 shown in FIG. The first telescopic cylinder 29 and the second telescopic cylinder 31 may be arranged in the boom 21 shown in FIG. 2 not only in the vertical direction but also in the horizontal direction.

[0026]

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. Note that only the differences from the first embodiment will be described in the second embodiment, and the same aspects as those in the first embodiment will be assigned the same reference numerals and explanations thereof will be omitted. As shown in FIG. 8, the second telescopic cylinder 31 is disposed in the cylinder tube 29c of the first telescopic cylinder 29 such that the second telescopic cylinder 31 can protrude and move, and the base end portion of the cylinder tube 31c of the second telescopic cylinder 31 is arranged outside. Piston 2 of the installed first telescopic cylinder 29
The first telescopic cylinder 29 is connected to the end of 9d on the tip side.
And the 2nd expansion-contraction cylinder 31 is connected on the coaxial line.

As shown in FIG. 9, the second oil passage 49 connected to the rod chamber 27b of the undulating cylinder 27 is connected to the bottom chamber 31a of the second telescopic cylinder 31, and the third oil passage 51 connected to the second operation control valve 43. Is connected to the rod chamber 31b of the second telescopic cylinder 31.

With this structure, the effect described in the first embodiment can be obtained, and as shown in FIG. 8, the boom 21 has a short total length in the fully contracted state. Even in the case of a simple boom 21, the first telescopic cylinder 29 and the second telescopic cylinder 3 are in a fully contracted state.
1 is accommodated in the boom 21, the first telescopic cylinder 2
Since the end of the boom 21 on the tip side of the boom 9 does not come into contact with a leveling cylinder (not shown) for leveling the work table 70 arranged at the tip of the boom 21, the first telescopic cylinder 29 and the second telescopic cylinder 31 are not It can be housed in the boom 21.

The second telescopic cylinder 31 provided in the first telescopic cylinder 29 has a second telescopic cylinder 31 as shown in FIG.
The distal end of the rod 31d1 of the telescopic cylinder 31 is connected to the piston 29d of the first telescopic cylinder 29, and the base end of the cylinder tube 31c of the second telescopic cylinder 31 is pivotally connected to the side wall 22a inside the base end of the base boom 22. You may do it.

Further, in the above-described first and second embodiments, the self-propelled aerial work vehicle 1 is shown as the vehicle on which the work device 20 is mounted. It may be a local work vehicle.

[0031]

As described above, according to the working apparatus of the present invention, the workbench can be lowered by constructing the second telescopic cylinder for expanding and contracting the boom so as to expand and contract in conjunction with the hoisting cylinder. When the hoisting cylinder is actuated to elevate and lower the boom in order to move the boom from the normal position to the high position, the second telescopic cylinder expands and the boom expands as the boom hoisting angle increases. Therefore, in the work apparatus according to the present invention, the extension amount of the boom at the upper position can be increased as compared with the boom provided with only the first telescopic cylinder. In addition, when the work platform is moving to a high position and the boom is laid down to lower the work platform to the ground, the undulation cylinder operates so that the boom lays down. As a result, the second telescopic cylinder contracts and the extension amount of the boom decreases. For this reason, in a region where the hoisting angle of the boom is small, the work platform can be moved within the movable range without restricting the operation of the boom. As a result, for example, if the boom is tilted from the state where the work platform is located near the limit line in the allowable movement range where there is no risk of the vehicle tipping over when the boom is fully extended, the boom will fall over. However, since the work table is contracted, the workbench can be moved inward of the limit line even in a region where the boom undulation angle is small. For this reason, even when the work range restricting device that restricts the operation of the boom exceeding the allowable movement range is mounted on the vehicle, the work table can be moved from the high position to the low position in a non-stop manner.

[Brief description of drawings]

FIG. 1 is a side view of an aerial work vehicle equipped with a work device according to a first embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of the work device according to the first embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram of the work device according to the first embodiment of the present invention.

FIG. 4 shows a movement range of a workbench moved by the work apparatus according to the first embodiment of the present invention.

FIG. 5 is a schematic diagram showing a main part of the work device according to the first embodiment of the present invention.

FIG. 6 shows a movement range of a workbench moved by the work apparatus according to the first embodiment of the present invention.

FIG. 7 shows a first telescopic cylinder and a second telescopic cylinder arranged in the boom according to the first embodiment of the present invention.

FIG. 8 is a partial cross-sectional view of a work device according to a second embodiment of the present invention.

FIG. 9 is a hydraulic circuit diagram of a work device according to a second embodiment of the present invention.

FIG. 10 is a cross-sectional view showing a main part of a work device according to a second embodiment of the present invention.

[Explanation of symbols]

9 Revolving base (base) 20 Working device 21 boom 22 Base boom (first boom) 23 Middle boom (second boom) 27 Lifting cylinder 29 First telescopic cylinder 31 Second telescopic cylinder

Claims (2)

[Claims] 1. A boom which is movably provided on a base and is telescopically movable by combining a first boom and a second boom in a telescopic manner, and a hoisting cylinder which hoists the boom with respect to the base. And a first telescopic cylinder and a second telescopic cylinder that are provided in a connected state in the boom and that extend and retract the second boom with respect to the first boom, and the first state in the connected state One of the telescopic cylinder and the second telescopic cylinder is connected to the first boom, and the other is connected to the second boom, and the second telescopic cylinder receives the hydraulic fluid discharged from the undulating cylinder and expands and contracts. The hoisting cylinder is configured to extend when the boom is hoisted, and the hoisting cylinder to retract when the boom is tilted. The first telescopic cylinder is configured to move forward. Working apparatus characterized by being configured to the derricking cylinder is telescopic movement independently. 2. The cylinder tube of one of the first telescopic cylinder and the second telescopic cylinder is the first tube.
A base end portion of the cylinder tube of the first telescopic cylinder or the second telescopic cylinder, which is disposed inside the cylinder tube of either the telescopic cylinder or the second telescopic cylinder so as to project and enter, and is disposed inside Is connected to the tip side end of the piston of the first telescopic cylinder or the second telescopic cylinder arranged outside, and the first telescopic cylinder and the second telescopic cylinder are positioned on the coaxial line. The working device according to claim 1, wherein