JPS5935838B2 - Work platform automatic balancing device for aerial work vehicles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an aerial work vehicle in which a work platform is attached to the tip of a two-stage telescopic boom device that can be raised and lowered, and the work platform is always level regardless of whether the boom device is extended or contracted or raised or lowered. This invention relates to an automatic balancing device for a work platform for an aerial work vehicle, which maintains the work platform in equilibrium.

The work platform of an aerial work vehicle must be kept horizontal and balanced at all times, as it is loaded with various work tools when a worker sits on it.

The work platform automatic balancing device for this purpose uses a link that is parallel to the boom device when the work platform is pivoted to the tip of the boom device, and a parallel link that is connected by this link, the boom device, the work platform, and the vehicle body. A device that formed a mechanism was considered.

However, if such a device were to be applied to a boom device that performs both telescoping and hoisting operations, the structure would become extremely complex and the weight would increase, so it is not necessarily suitable for aerial work vehicles. I couldn't say that.

Therefore, a method was proposed in which a pulley device was used to apply a constant tension to the workbench using a rope, thereby holding the workbench horizontally regardless of the expansion and contraction of the boom device.

A device using such a pulley device has a simple structure and smooth operation, and is desirable as an automatic balance device for a work platform of an aerial work vehicle.

However, with conventional systems, the telescoping motion of the boom device and the operation of the pulley device did not necessarily match, so for example, when the boom device tilted at a large angle, the rope could become loose, or conversely, a large tension could occur. In some cases, the workbench would tilt.

Furthermore, the rope may obstruct the operation of the boom device,
There was even a risk that the rope would be severed if activated forcibly.

In view of the above points, the present invention allows the operation of the pulley device to completely match the extension/contraction and raising/lowering movements of the boom device, and maintains constant tension on the workbench using a flexible cable such as a rope of the pulley device. The first object of the present invention is to provide an automatic work platform balancing device for an aerial work vehicle that always maintains the work platform horizontally and balanced by adding the above.

In order to achieve this objective, the work platform automatic balancing device for an aerial work vehicle according to the present invention is provided with a fixed pulley that rotates relative to the inclination of the boom device at the pivot point of the boom device to the vehicle body. In addition, a fixed pulley of the same diameter that rotates with the work platform is attached to the pivot point to the work platform boom device, and a flammable cable such as a rope is connected between these fixed pulleys via a movable pulley. The articles are being passed.

In this way, when the boom device extends or contracts, the movable pulley moves to maintain a constant tension in the cable between the fixed pulleys, and when the boom device moves up or down, the two fixed pulleys rotate by the same angle. It is designed to keep the tension of the cable constant by moving the cable.

In this way, the tension applied to the workbench by the cable is kept constant, so if you constantly apply a force in the opposite direction to counteract this tension on the workbench, the workbench will be balanced horizontally. Retained.

This force in the opposite direction can be obtained, for example, simply by shifting the center of gravity of the workbench.

However, with such devices, an external force in the same direction as the tension applied by the cable is applied to the workbench,
If a worker moves on the workbench, the workbench may sway or tilt.

Particularly when performing precision work, it is necessary to hold the workbench firmly and horizontally.

Therefore, the present invention ensures that the work platform is always held horizontally and balanced regardless of the extension/contraction and raising/lowering operations of the boom device, and that this state is reliably maintained even if the work platform is subjected to external force in any direction. A second object of the present invention is to provide a work platform automatic balancing device for an aerial work vehicle using a pulley device.

According to the second aspect of the present invention, another set of flexible cables is provided on the fixed pulley of the chassis pivot portion of the boom device and the fixed pulley of the work platform pivot portion, respectively, each set being opposite to the other set. The hooks pass through two sets of movable pulleys that can be wound in the same direction and move these two sets of flexible cables independently.

In this way, the two sets of cables constantly apply tension of the same magnitude to the workbench from opposite directions, thereby locking the workbench against external forces.

Hereinafter, the present invention will be described in detail with reference to the drawings. In FIG. 1, a support 2 is erected on the body 1 of an aerial work vehicle, and this support 2 has a base bracket for a two-stage telescopic boom device 3. 4 is pivoted.

The two-stage telescopic boom device 3 includes a base boom 5 and a tip boom 6 fitted into the base boom 5, and the base bracket 4 is fixed to the base boom 5.

A bracket 8 fixed to a workbench 7 is pivotally attached to the tip of the tip boom 6.

A hydraulic cylinder 9 for raising and lowering is provided between the base boom 5 and the column 2, and the telescopic boom device 3 performs a raising and lowering operation by the extending and contracting operation of this hydraulic cylinder 9.

Furthermore, a telescopic hydraulic cylinder (not shown) is provided between the base boom 5 and the front boom 6, and its operation moves the front boom 6 into and out of the base boom 5, allowing the telescopic boom to move in and out of the base boom 5. The device 3 is designed to extend and contract.

A base fixed pulley 10 is attached to the base pivot portion of the telescopic boom device 30.
is provided.

The base fixing pulley 10 is coaxial with a pivot shaft 11 that pivotally connects the base bracket 4 to the column 2, and is fixed to the column 2.

Therefore, when the telescopic boom device 3 moves up and down by an arbitrary angle, the fixed pulley 10 rotates relative to the telescopic boom device 3 by the same angle.

Further, a tip fixing pulley 12 is provided at the pivot point of the workbench 7 at the tip of the telescopic boom device 3.

This tip fixing pulley 12 is fixed to a pivot shaft 13 fixed to a bracket 8 of the workbench 7.

This pivot shaft 13 is rotatably supported at the tip of the tip boom 6, so that the work platform 7 can rotate relative to the fixed pulley 12 and the telescopic boom device 3. ing.

These base fixed pulley 10 and tip fixed pulley 12 have the same diameter.

In FIGS. 2 and 3, one end of the base cable 14 is fixed to the base fixing pulley 10 by a fastening piece 15. As shown in FIGS.

The base rope 14 is wound counterclockwise around the fixed base pulley 10, guided into the telescopic boom device 3 through the insertion hole 16 of the base boom 5, and wound around the movable pulley device 18 via the guide roller 17. The end portion thereof is locked to a locking portion 19 provided at the base side end of the tip boom 60.

The tip fixed pulley 12 has a fastening piece 2 at one end of the tip cable 20.
The tip cable 20 is wound clockwise around the fixed pulley 12, and then wrapped around the movable pulley device 18 via the guide roller 22, and the other end is attached to the base boom 5. It is locked by a locking part 23 provided at the tip.

The movable pulley device 18 consists of two pulleys 24.25 around which the base cable 14 and the tip cable 20 are wound, respectively, and a link 26 that connects these pulleys 24.25. can move back and forth while being guided by a movable pulley guide 27 provided inside the base boom 5 and a movable pulley guide 28 provided outside the tip boom 6.

Note that if the base boom 50 has a sufficient width, the link 26 can be omitted by arranging the two pulleys 24 and 25 of the movable pulley device 18 on the same axis.

The base cable 14 and the tip cable 20 are wires, ropes,
It is a flexible rope such as a chain.

If a chain is used, sprocket wheels are used as the fixed pulley 10.12 and the pulley 24.25 of the movable pulley device 18.

The center of gravity of the workbench 70 is located forward of the vertical plane passing through the pivot shaft 13 (
(on the left side of the figure), and constantly applies a force to the tip fixed pulley 12 to rotate it counterclockwise.

In addition to this, such force can also be applied using a spring or the like.

In addition, as another embodiment, the tip cable 20 is wound counterclockwise around the tip fixed pulley, and a force that tries to rotate the tip fixed pulley 12 clockwise due to the weight of the workbench 7 or a spring is applied. You can also add it all the time.

In the case of the embodiment shown in FIG. 3, such a force is applied to the fixed end pulley 12 to rotate it in the counterclockwise direction, but on the other hand, the movable pulley device 18 is controlled by the base rope 14. Since forward movement (to the left in the figure) is prevented, a tension force is generated in the tip cable 20 that opposes this force, causing the tip fixed pulley 12 and the work platform 70 fixed thereto to rotate. prevent.

Therefore, the workbench 7 is held horizontally.

Now, if the luffing hydraulic cylinder 9 is extended and the telescopic boom device 3 is made to take an inclination angle larger than the angle θ (radian) from the illustrated position, the telescopic boom device 3
rotates clockwise around the base fixed pulley 10 by an angle θ.

This is basically the same thing as fixing the telescopic boom device 3 and rotating the fixed pulley 10 counterclockwise by an angle θ, so for convenience of explanation, FIG. shows the fixed pulley 10 as if it were rotated.

In FIG. 3, when the base fixed pulley 10 with radius r rotates counterclockwise by an angle θ, this fixed pulley 10
The base cable 14, which is wound counterclockwise around the base cable 14, is let out by a length rθ.

On the other hand, since a tension force is applied to the tip cable 20 due to the force that causes the tip fixed pulley 12 to rotate counterclockwise, the movable pulley device 18 moves forward.

This distance of movement is half the length of the base cable 14, that is, rθ/2.

When the movable pulley device 18 moves by rθ/2, the tip cable 2
0 is a fixed pulley 1 at the tip that is loosened by twice the length, that is, rθ, and is constantly applied with a counterclockwise rotational force.
2 rotates and winds up the loose end rope 20 due to the slack amount rθ.

Since the tip fixed pulley 12 has the same diameter as the base fixed pulley 10, its radius is r.

Therefore, the tip fixed pulley 12 extends the tip rope 20 by a length r.
The rotation angle when winding by θ is θ.

That is, when the base fixed pulley 10 relatively rotates counterclockwise by an angle θ, the tip fixed pulley 12 also rotates counterclockwise by an angle θ.

In other words, when the telescopic boom device 3 rotates clockwise around the base fixed pulley 10 by an angle θ, the tip fixed pulley 12 rotates at an angle θ counterclockwise with respect to the telescopic boom device 3.
Rotate only.

Therefore, the workbench 7 fixed to the tip fixed pulley 12 is held in its original state, that is, in a horizontal state.

In this state, the force that attempts to rotate the tip fixed pulley 12 counterclockwise again balances the tension of the tip cable 20, and an equilibrium state is maintained.

When the telescopic boom device 3 is rotated counterclockwise,
Needless to say, the workbench 7 is rotated clockwise by the same angle relative to the telescopic boom device 3, and the workbench 7 is held horizontally.

Next, when the front boom 6 is extended from the base boom 5 by a telescopic hydraulic cylinder (not shown) and the telescopic boom device 3 is extended, the front boom 6 is moved by a distance l as shown in FIG. Suppose you move forward.

At this time, since the length of the base rope 14 does not change, the movable pulley device 18 moves half the distance traveled by the tip boom 6, that is, l.
Move forward by /2.

As the movable pulley device 18 moves forward by l/2, the front part of the tip rope 20 extends by twice the length, that is, l, but the fixed tip pulley 12 also moves forward by a distance l. , the tip fixed pulley 12 does not rotate.

Therefore, the workbench 7 is held horizontally and balanced.

When retracting the telescopic boom device 3, the movable pulley device 18
moves rearward to absorb the amount of fluctuation of the base cable 14 and the tip cable 20, and the workbench 7 is held horizontally balanced.

As described above, according to the present invention, by constantly applying a rotational force in the counterclockwise direction to the fixed end pulley 12 due to the weight of the workbench 7, etc., regardless of the up-and-down or telescoping operation of the telescopic boom device 3. An automatic workbench balancing device that can always hold the workbench 7 horizontally is obtained.

The counterclockwise rotational force applied to the tip fixed pulley 12 can be increased by attaching the bracket 8 to the side of the workbench 7 and moving it far away from the pivot shaft 13, which is the center of gravity. can do.

By increasing this force, a stable automatic balance device for the workbench can be obtained in which the workbench 7 does not easily sway even if an external force is applied.

However, if this rotational force is increased, the frictional force of the movable pulley device 18 increases, and the telescopic boom device 3
There is a problem in that the undulation or expansion/contraction operations cannot be performed smoothly.

Moreover, even if the rotational force is set large, when the telescopic boom device 3 is lowered, the actuating base 7 may get caught on a building, causing the tip fixed pulley 12 to rotate clockwise. If a large external force is applied, the workbench 7
There is a risk of tipping or falling.

Examples that solve these problems will be described below.

In Figures 5, 6a, 6b, 7a and 7b, 2.3.
Components similar to those in the embodiment shown in FIG. 4 are given the same reference numerals.

On the = side of the telescopic boom device 29, as shown in FIGS. 5, 6a and 7a, there is provided a pulley device completely similar to the embodiment shown in FIGS. 2, 3 and 4.

That is, the base cable 14 is wound counterclockwise around the fixed base pulley 10, and after the base cable 14 is wrapped around the pulley 24 of the movable pulley device 18, the end thereof is attached to the base of the tip boom 60. It is locked by a locking part 19 at the side end.

Further, a tip cable 20 is wound clockwise around the fixed tip pulley 12, and this tip cable 20 is attached to the movable pulley device 1.
After being wrapped around the pulley 25 of 8, the end is attached to the base boom 5.
It is locked by a locking part 23 at the tip of the.

At the other end of the telescopic boom device 29, there are shown in FIGS. 5 and 6b, ?
A further pulley arrangement is provided as shown in Figure b.

That is, a second base fixing pulley 30 having the same diameter and the same axis as the base fixing pulley 10 is fixed to the support column 2 .

Further, a second tip fixing pulley 3 having the same diameter as the tip fixing pulley 12 and therefore the same diameter as the second base fixing pulley 30 is attached to the pivot shaft 13 rotatably supported at the tip of the telescopic boom device 29 .
1 is fixed.

One end of the second base cable 32 is fixed to the second base fixing pulley 30 by a fastening piece 33.
2 is wound clockwise around the second fixed base pulley 30, guided into the telescopic boom device 29 through the insertion hole 34 of the base boom 5, and wound around the second movable pulley device 36 via the guide roller 35. The end portion thereof is locked to a locking portion 37 provided at the base side end of the tip boom 60.

One end of the second tip cable 38 is fixed to the second tip fixing pulley 31 by a fastening piece 39.
8 is wound counterclockwise around the second fixed end pulley 31 and then around the second movable pulley device 36 via the guide roller 40, and the other end is provided at the end of the base boom 5. It is locked by a locking part 41.

The second movable pulley device 36 is similar to the movable pulley device 18, and includes two pulleys 42 and 43 around which the second base cable 32 and the second tip cable 38 are wound, respectively, and these pulleys 4.
2 and 43, and this second movable pulley device 36 includes a second movable pulley device 36 provided on the inside of the base boom 5.
It is guided by a movable pulley guide 45 and a second movable pulley guide 46 provided outside the tip boom 6 so that it can move back and forth.

Therefore, the pulley devices provided on both sides of the telescopic boom device 29 are arranged such that the base cable 14, the tip cable 20, the second base cable 32, and the second tip cable, as is clear from FIGS. 6a and 6b. The direction of the winding with the part cable 38 is opposite.

As a result, even if an external force is applied to the workbench 7, the tip cable 20
Alternatively, the rotation of the pivot shaft 130 is prevented by the tension of any one of the second tip cables 38, so that the workbench 7 is prevented from rotating, and the workbench 7 is held in horizontal equilibrium.

Here, when the telescopic boom device 29 is tilted by an angle θ (radian), the base fixed pulley 10 and the second base fixed pulley 30 are both relative to the telescopic boom device 29 in the counterclockwise direction by the angle θ. Rotate around the target.

Since the radii of the base fixing pulley 10 and the second base fixing pulley 300 are both r, the base cable 14 is paid out by the length rθ by this rotation, and the second base cable 32 is extended by the length rθ.
only to be wound up.

As a result, the second movable pulley device 36 is moved rearward (to the right in the figure) by rθ/2, and pulls the second tip cable 38 by the length rθ.

By pulling the second tip cable 38 by the length rθ in this manner, the second tip fixing pulley 31 is rotated counterclockwise by the angle θ.

At this time, the tip fixing pulley 12, which is fixed to the same pivot shaft 13 as the second tip fixing pulley 31, also rotates counterclockwise by an angle θ, and winds the tip rope 20 by a length rθ.

Therefore, the movable pulley device 18 is moved forward by rθ/2, and the base fixed pulley 10 also absorbs the length rθ of the let-out base cable 14.

In this way, the tip fixed pulley 12 and the second tip fixed pulley 31
is held in equilibrium while being rotated counterclockwise by an angle θ.

At this time, the telescopic boom device 29 is rotated clockwise by the angle θ, so the workbench 7 is held horizontally after all.

Needless to say, when the telescopic boom device 29 is rotated counterclockwise, each pulley device operates in the opposite direction, and the work platform 7 is held horizontally.

Next, if the tip boom 6 is moved forward by a distance l as shown in FIGS. 7a and 7b, and the telescopic boom device 29 is extended, both the movable pulley device 18 and the second movable pulley device 36 Move forward by l/2.

This movement creates a margin of length l in the front portions of the tip cable 20 and the second tip cable 38, but at the same time, the tip fixing pulley 12 and the second tip fixing pulley 31 also have a distance l. Because of the forward movement, the leading strands 20 and the second trailing strands 38 remain taut, and the tension thereby applied is also maintained in balance.

In this case, the tip fixed pulley 12 and the second tip fixed pulley 3
1 does not rotate, the work table 7 fixed thereto also does not rotate and is held horizontally.

When retracting the telescopic boom device 29, the movable pulley device 1
8 and the second movable pulley device 36 simultaneously move rearward by the same amount to hold the work platform 7 horizontally balanced.

In the above embodiment, two sets of pulley devices are provided on both sides of the telescopic boom device 290, but the movable pulley device 18 and the second movable pulley device 36 are arranged so that they can move relative to each other. If so, they can also be provided on one side.

In this way, by making the base fixing pulley 10 also serve as the second base fixing pulley 30 and the tip fixing pulley 12 also serving as the second tip fixing pulley 31, each can be made into one pulley. .

In this case, the base cable 14 and the second base cable 32 are configured as one cable, and one fastening piece 1 is attached to the base fixing pulley 12.
If it is fastened at 5, the number of fastening pieces can also be reduced.

The same applies to the front end rope 20 and the second front end rope 38.

As described above, according to this second invention, the tip cable 2
0 and the second tip cable 38 always apply tension in the opposite direction to the tip fixing pulley 12 and the second tip fixing pulley 31, and thus to the workbench 7, so no matter which direction the external force is received. This provides an automatic work platform balancing device for an aerial work vehicle in which the work platform 7 is held in balance and is prevented from tilting or overturning.

Furthermore, when the telescopic boom device 29 is raised or lowered, the work platform 7 is rotated by the pulley device in the opposite direction to the telescopic boom device 29 by the same angle as the angle of the raised or lowered movement, so that the operation is smooth and always This provides an automatic work platform balancing device for an aerial work vehicle in which the work platform 7 is reliably held horizontally.

[Brief explanation of the drawing]

FIG. 1 is a schematic side view showing an embodiment of an aerial work vehicle equipped with an automatic work platform balancing device according to the present invention, and FIG. FIG. 3 is a partial sectional side view taken from the line A-A in FIG. 2 showing the operation of the telescopic boom device during raising and lowering, and FIG. 4 is a cross-sectional plan view of the main parts showing the embodiment. FIG. 5 is a partial cross-sectional side view similar to FIG. 3 showing the operation when the boom is extended; FIG. Lines A-A and B-B in Fig. 5 show the operation of the device when raising and lowering, respectively.
Sectional side view from line, No. 7a. Figure 7b is a cross-sectional side view similar to Figures 5a and 5b, showing the operation of the telescopic boom device when it is extended. 1...Vehicle body, 2...Strut, 3...
... Two-stage telescopic boom device, 5 ... Base boom, 6 ... Tip boom, 7 ... Work platform,
9... Hydraulic cylinder for luffing, 10...
Base fixed pulley, 11... Pivoting shaft, 12...
...Fixed end pulley, 13...Pivot shaft, 14...
...Base cord, 15...Fixing piece, 18...
...Moving pulley device, 20... Tip rope, 21
...Fixing piece, 29...Two-stage telescopic boom device, 30...Second base fixed pulley, 31...
...Second tip fixing pulley, 32...Second base rope, 33...Fixing piece, 36...Second
Movable pulley device, 38... Second tip rope, 39...
...Fixing piece.

Claims (1)

[Scope of Claims] 1. A two-stage telescopic boom device 3 consisting of a support post 2 erected on a vehicle body 1, a base boom 5 and a tip boom 6 pivotally connected to the support support so as to be able to rise and fall; In an aerial work vehicle equipped with a work platform 7 pivotally attached to the tip of the boom device 3; a fixed pulley 10; a tip fixed pulley 12 having the same diameter as the base fixed pulley 10 and fixed to the work platform 7 and attached to a pivot portion of the work platform 7 to the telescopic boom device 3; A movable pulley device 18 provided between the base fixed pulley 10 and the tip fixed pulley 12; one end fixed to the base fixed pulley 10 and the other end fixed to the tip boom 6; is wound around the movable pulley device 18; one end is connected to the fixed end pulley 12, and the other end is connected to the base boom 5.
, and the middle portion thereof is connected to the movable pulley device 18.
An automatic balancing device for a work platform of an aerial work vehicle, comprising a tip cable 20 wound around the work platform. 2. A two-stage telescopic boom device 29 consisting of a pillar 2 erected on the vehicle body 1, a base boom 5 and a tip boom 6 pivotally attached to the pillar 2 so as to be able to rise and fall; and this telescopic boom device 29.
In an aerial work vehicle equipped with a work platform 7 pivotally attached to a tip end of the platform; °30; the telescopic boom device 2 of the work platform 7;
Tip fixing pulleys 12, 31 having the same diameter as the base fixing pulleys 10, 30 and fixed to the workbench 7; the base fixing pulley 10°30 and the tip. A pair of movable pulley devices 18 and 36 are provided between the fixed pulleys 12 and 31; one end is fixed to the base fixed pulley 10, the other end is fixed to the tip boom 6, and the intermediate portion thereof is fixed to the base fixed pulley 10, and the other end is fixed to the tip boom 6. One movable pulley device 1 of a pair of movable pulley devices 18, 36
8; one end is fixed to the tip fixed pulley 12, the other end is fixed to the base boom 5, and the middle part thereof is wrapped around the one movable pulley device 18. a tip cable 20; one end of which is connected to the base fixed pulley 10;
. Second base cord 32 wrapped around device 36
One end is fixed to the tip fixing pulleys 12, 31, and both are wound in the opposite direction to the tip cable 20, the other end is fixed to the base boom 5, and the middle part thereof is The second tip cable 3 wrapped around the other movable pulley device 36
8. A work platform automatic balancing device for an aerial work vehicle, comprising: