JP2001063993A - Device for levelling high lift working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device for levelling a high lift working vehicle, capable of eliminating the delay of the levelling of a working floor from the hoisting of a boom at starting the hoisting of the boom and holding the working floor in a balanced condition in the case of part of hydraulic fluid supply passage to a levelling cylinder being broken. SOLUTION: When the hoisting of a boom 14 is started in the condition that the boom 14 is not hoisted (the operation of a levelling cylinder 23 is stopped), an additional flow for restricting the delay of the operation of the levelling cylinder 23 from the hoisting of the boom 14 at starting the hoisting of the boom 14 is added to the levelling flow of hydraulic fluid required to support a working floor in a balanced condition. The hydraulic fluid of a corrected hydraulic fluid flow (a levelling flow plus an additional flow) obtained in this way is supplied to the levelling cylinder 23 by driving a balance control valve 55.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leveling device for an aerial work vehicle capable of maintaining a work floor provided at a tip portion of a boom which can be raised and lowered irrespective of the boom's posture.

[0002]

2. Description of the Related Art Various types of leveling (balancing) devices have been devised. For example, a lower leveling cylinder which expands and contracts according to the boom up / down movement, and a leveling device provided at the tip of the boom. And an upper leveling cylinder that supports the work floor in a horizontal state by an oil passage in a closed circuit. In the leveling device having such a configuration, the hydraulic oil is supplied / discharged from the lower leveling cylinder to the upper leveling cylinder in accordance with the up / down of the boom, so that the expansion / contraction operation of the upper leveling cylinder is synchronized with the up / down of the boom.

[0003] In such a leveling device, since the lower leveling cylinder and the upper leveling cylinder are connected to a closed circuit, there is an advantage that the leveling of the work floor does not delay following the rise and fall of the boom. A locking circuit (for example, a double holding valve) is provided in the oil passage immediately below the upper leveling cylinder so that the leveling cylinder can be fixed and held when the boom is stopped, but the hydraulic oil supply oil passage to the leveling cylinder is not provided. When a part is broken, there is a disadvantage that the locking circuit does not work while residual pressure is present in the oil passage, and the work floor cannot be balanced during that time.

As another leveling device capable of compensating for such a drawback, a locking circuit is provided immediately below the leveling cylinder, and supply of hydraulic oil to the leveling cylinder is controlled by electromagnetically driving a balance control valve from a controller. In some cases, the neutral position of the balance control valve is so-called ABT connected. In such a configuration, in order to stop the operation of the leveling cylinder, the balance control valve may be set to the neutral position, and the oil passage below the locking circuit may be communicated with the tank.
Even if part of the oil passage is broken, the leveling cylinder can be hydraulically locked instantaneously by valve control from the controller, making it possible to prevent the work floor from losing equilibrium. .

[0005]

However, in the leveling device having such a configuration, the oil passage below the locking circuit communicates with the tank when the balance control valve is in the neutral position and the operation of the leveling cylinder is stopped. Therefore, when the leveling cylinder is to be operated next, it is necessary to first supply hydraulic oil into the oil passage to increase the pressure. For this reason, when raising and lowering is started from a state where the boom is not raised and lowered (that is, a state where the operation of the leveling cylinder is stopped), a control value for operating the leveling cylinder in accordance with the boom up and down is output ( Even if hydraulic oil is supplied), the operation of the leveling cylinder starts later than the start of the boom. For this reason, the leveling of the work floor is delayed by the ups and downs of the boom, and during that time, the work floor is tilted, causing a problem that the workers and the mounted components are in an unstable state.

SUMMARY OF THE INVENTION The present invention has been made in view of such a problem, and the leveling of the work floor is not delayed from the boom up / down at the start of the boom up / down, and the hydraulic oil supply oil to the leveling cylinder is provided. It is an object of the present invention to provide a leveling device for an aerial work vehicle capable of maintaining an equilibrium state of a work floor even when a part of a road is broken.

[0007]

In order to achieve the above object, according to the present invention, there is provided a vehicle body, a boom provided on the vehicle body so as to be able to move up and down, and a boom mounted on a tip end of the boom so as to be swingable up and down. Work floor, a first hydraulic actuator for raising and lowering the boom (for example, the up-and-down cylinder 16 in the embodiment), a second hydraulic actuator for rocking the work floor up and down (for example, the leveling cylinder 23 in the embodiment), and an external operation. Commanding means (for example, the boom operation lever 27 in the embodiment) for issuing a command to raise and lower the boom, and control means for controlling the first hydraulic actuator to raise and lower the boom in response to the operation of the commanding means for raising and lowering. (For example, the controller 40 and the up-and-down control valve 51 in the embodiment) and the working floor are The leveling device of the aerial work vehicle is configured to include a balance control unit (for example, the controller 40 and the balance control valve 55 in the embodiment) that performs control for operating the second hydraulic actuator so as to support in a state. The equilibrium control means controls the flow rate of hydraulic oil supplied to the second hydraulic actuator to operate the second hydraulic actuator. At the start of the boom up / down operation, the second hydraulic actuator controls the boom up / down operation. The second hydraulic actuator is operated at a corrected hydraulic oil flow rate that can suppress the operation delay.

[0008] In the leveling device having such a configuration, the equilibrium control means for controlling the flow rate of the working oil supplied to the second hydraulic actuator to keep the work floor in an equilibrium state is provided when the boom is raised and lowered. Since the second hydraulic actuator is operated with the corrected hydraulic oil flow rate that can suppress the operation delay of the hydraulic actuator with respect to the boom up and down, the leveling (balancing) of the work floor is delayed from the boom up and down at the start of the boom up and down. There is nothing. Also, unlike a leveling device configured by connecting upper and lower leveling cylinders with an oil path,
Since the operation of the hydraulic actuator can be directly controlled by the balance control means, a locking circuit (for example, the double holding valve 56 in the embodiment) is provided in the oil passage immediately below the second hydraulic actuator,
If the neutral position of the balance control valve is set to the ABT connection position, the balance control valve can be instantaneously switched to the neutral position even if a part of the oil passage is broken during the operation of the second hydraulic actuator. Accordingly, it is possible to lock the second hydraulic actuator hydraulically and to maintain an equilibrium state of the work floor.

Here, a supporting force detecting means (for example, a supporting force detector 46 in the embodiment) for detecting a supporting force of the second hydraulic actuator is provided, and the corrected hydraulic oil flow rate is detected by the supporting force detecting means. It is preferable that the setting is made in accordance with the magnitude of the supporting force of the second hydraulic actuator. According to such a configuration, the second
Irrespective of the supporting force of the hydraulic actuator, that is, the magnitude of the load applied to the work floor, accurate leveling can always be performed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an aerial work vehicle 10 provided with the leveling device according to the present invention.
A vehicle body 11 of the aerial work vehicle 10 has a driver's seat 12 at the front, and a nested boom 14 is pivotally connected to a foot pin 15 at a swivel 13 provided at the rear. The swivel base 13 can be horizontally swiveled by a swivel motor 18 provided at a lower part thereof, and the boom 14 can be extended and retracted by an extendable cylinder 17 incorporated therein. Further, between the boom 14 and the swivel base 13, the undulating cylinder 1 is provided.
6 are provided so that the boom 14 can be raised and lowered. Jacks 19 projecting downward and supporting the vehicle body 11 are provided on the front, rear, left and right sides of the vehicle body 11, and each jack 19 is extended and stored by manually operating a jack operating lever (not shown) provided behind the vehicle body 11. It is possible to do.

At the tip of the boom 14, there is provided a work floor 21 for boarding an operator via a vertical post 20. The vertical post 20 is connected to the boom 1 by the leveling cylinder 23.
4, so that it is always kept vertical regardless of the up-and-down posture, and the floor surface of the work floor 21 is always kept horizontal (details will be described later). A swing motor 22 is provided in the work floor 21, whereby the work floor 21 can swing (horizontal rotation) around the vertical post 20.

An upper operation device 25 and a lower operation device 26 are provided behind the work floor 21 and the vehicle body 11, and a boom operation lever 27 and a work floor operation lever 28 provided on these operation devices 25 and 26 are provided. By manual operation, the boom 14 can be raised, contracted, turned, and the work floor 21 swung. The boom operation lever 27 is capable of tilting to the front and back, right and left, and twisting around the axis from the neutral position, and tilting the boom 14 up and down by tilting back and forth, and expanding and contracting the boom 14 by tilting left and right.
In addition, the boom 14 is turned by the twist (the swivel table 13 is turned).
Can be performed. Further, the work floor operation lever 28 can be tilted from the neutral position to the left and right, whereby the work floor 21 can be swung horizontally around the vertical post 20 to swing. I have.

In the vicinity of the boom operation lever 27, there is provided a mode selection switch 29 capable of selecting one of a normal mode and a horizontal / vertical movement mode. When the normal mode is selected by the mode selection switch 29, the boom 14 can be raised, contracted, and turned as described above, but when the horizontal / vertical movement mode is selected, the boom 1 is moved.
4 (that is, the work floor 21) can be moved horizontally and vertically. That is, when the horizontal / vertical movement mode is selected by the mode selection switch 29, the boom operation lever 27 is tilted back and forth and left and right,
The work floor 21 can be moved in the horizontal direction in the operation direction, and the work floor 21 can be vertically moved up and down by twisting the boom operation lever 27.

The ups and downs, expansion and contraction, turning operation of the boom 14 and swinging operation of the work floor 21 will be described in more detail with reference to FIG. When both operation levers 27 and 28 are operated, the operation signal is output to the controller 40. The controller 40 controls the undulation control valve 5 based on the operation signal.
1. The expansion / contraction control valve 52 and the swing control valve 53 (all of which are electromagnetic proportional directional flow control valves) are electromagnetically driven to control the supply of hydraulic oil to the up / down cylinder 16, the expansion / contraction cylinder 17, and the swing motor 18, and The control valve 54 and the balance control valve 55 (both of which are electromagnetic proportional direction control valves) are electromagnetically driven to perform the oscillating motor 22 and the leveling cylinder 23.
Control the supply of hydraulic oil to the engine. As a result, the boom 14 and the work floor 21 operate in accordance with the operation of the operation levers 27 and 28, and the work floor 21 is leveled (held in an equilibrium state).

Here, when the horizontal / vertical movement mode is selected by the mode selection switch 29, the controller 40 needs the position information of the tip of the boom 14; Information on the up-and-down angle and length of the boom 14 detected by the angle detector 41 and the length detector 42, and information on the turning angle of the turntable 13 detected by the turning angle detector 43 provided in the vehicle body 11. Is calculated from The work floor 21 has a swing angle detector 44 for detecting a swing angle of the work floor 21 with respect to the boom tip, and a balance detector 45 for detecting the degree of balance (deviation from the equilibrium state) of the work floor 21. And a support force detector 46 for detecting the support force of the work floor 21 by the leveling cylinder 23 (both are not shown in FIG. 2). These detection information are also input to the controller 40. It has become. The supporting force of the leveling cylinder 23 is detected by measuring the pressure of the hydraulic oil in the leveling cylinder 23, the axial force of the rod, and the like.

When performing an aerial work using the aerial work vehicle 10 having such a configuration, first, a worker (driver) drives from the driver's seat 12 to travel on the road, and the aerial work vehicle 10 is moved to the work site. Move to When the vehicle travels on the road in this manner, the boom 14 is fully retracted, and the storage state is such that the boom 14 is folded down to the boom receiver 31. When you arrive at the work site,
An operator operates a jack operating lever (described above, not shown) to protrude each jack 19 and support the vehicle body 11. When the vehicle body 11 is supported by all the jacks 19, the operator gets on the work floor 21, operates the boom operation lever 27 and the work floor operation lever 28 from the upper operation device 25, and moves the boom 14 up and down, expands, contracts, and works. The work is performed by swinging the floor 21 to move the work floor 21 to a desired high position.

Next, the operation of the leveling device for the work floor 21 will be described. FIG. 1 shows a configuration of a leveling device provided in the aerial work vehicle 10. As shown in FIG. 1, hydraulic oil discharged from a hydraulic pump P flows from an oil passage 61 to an up / down control valve 51. Supplied and
The oil is supplied from the oil passage 62 to the balance control valve 55. The up / down control valve 51 and the equilibrium control valve 55 are electromagnetic proportional type directional flow control valves in which the neutral position is in a so-called ABT connection state. The spool (not shown) is electromagnetically driven by the controller 40 and the up / down cylinder 16 or the leveling cylinder. The flow rate of hydraulic oil supplied to the control unit 23 is controlled. The oil passages 65 and 66 immediately below the leveling cylinder 55 are provided with a double holding valve 56 capable of hydraulically locking the leveling cylinder 23. An oil passage (flexible) communicating the double holding valve 56 and the balance control valve 55 is provided. The hoses 63 and 64 are provided inside the boom 14.

When the boom operation lever 27 is operated and an operation signal is input, the controller 40 drives the up / down control valve 51 to raise / lower the hydraulic oil at a flow rate proportional to the operation amount of the boom operation lever 27. It is supplied to the cylinder 16. Thus, the boom 14 moves up and down at a speed proportional to the operation amount of the boom operation lever 27.

When the boom 14 is raised and lowered in this way, the controller 40 controls the undulation angle detector 41 and the balance detector 4
Based on the information from 5, a hydraulic oil flow rate (referred to as a leveling flow rate) required to support the work floor 21 in an equilibrium state is calculated, and the hydraulic oil having such a flow rate is supplied to the leveling cylinder 23. , The balance control valve 55 is driven. Thereby, the work floor 21 is moved according to the ups and downs of the boom 14.
Are supported in equilibrium. Further, when the up-and-down movement of the boom 14 is stopped, the operation of the leveling cylinder 23 needs to be stopped, so that the spool of the balance control valve 55 is positioned at the neutral position. Therefore, the oil passages 63 and 64 below the double holding valve 56 communicate with the tank T, and the internal pressure decreases. As a result, the check valve of the double holding valve 56 is connected to the oil passages 65 and 66.
The leveling cylinder 23 is in a hydraulically locked state because the working oil inside is sealed.

In the state where the spool of the balance control valve 55 is located at the neutral position and the operation of the leveling cylinder 23 is stopped, the double holding valve 5
Since the oil passages 63 and 64 below the tank 6 communicate with the tank T and are in a reduced pressure state, when the leveling cylinder 23 is operated next time, the oil passages 63 and 64 are first operated.
It is necessary to increase the pressure in the cylinder 4, and for that purpose, it is necessary to supply extra hydraulic oil into the oil passages 63, 64 (otherwise, the leveling cylinder 23 may not be able to operate due to the ups and downs of the boom. Will occur).

For this reason, when the boom 14 is to be started up and down from a state in which the boom 14 is not up and down (ie, a state in which the operation of the leveling cylinder 23 is stopped), the leveling at the start of the up and down movement of the boom 14 is performed. A hydraulic oil flow rate (additional flow rate) for suppressing an operation delay of the boom 14 of the cylinder 23 with respect to the ups and downs of the boom 14 is added to the leveling flow rate, and a corrected hydraulic oil flow rate obtained in this manner, that is, the boom 14 of the leveling cylinder 23 is added. The equilibrium control valve 55 is driven such that the hydraulic oil at a flow rate (leveling flow rate + additional flow rate) sufficient to suppress the operation delay with respect to is supplied to the leveling cylinder 23. This additional flow rate is determined by the leveling cylinder 23.
Is added only for a predetermined time at the start of the operation. Further, adding the additional flow rate to the leveling flow rate for a predetermined time as described above corresponds to increasing the opening of the balance control valve 55 for a predetermined time.

Here, the additional flow rate depends on the length of the oil passages (flexible hoses) 63 and 64 between the balance control valve 55 and the double holding valve 56 and the oil passage 6.
It is determined in consideration of the expansion rate with respect to the pressure increase of 3,64. The maximum value of the additional flow rate and the like may be constant regardless of the magnitude of the supporting force of the leveling cylinder 23 on the work floor 21. However, in order to accurately correct the operation delay of the leveling cylinder 23 and perform leveling, the leveling It is preferable that the setting is variably set according to the magnitude of the supporting force of the cylinder 23. In order to achieve such a configuration, the additional flow rate data for each supporting force of the leveling cylinder 23, which is obtained in advance, is stored in the storage device of the controller 40, and when the boom 14 starts to undulate, the supporting force is detected. The additional flow rate data corresponding to the supporting force of the leveling cylinder 23 at that time may be called based on the detection information from the vessel 46. In addition, the time-varying pattern of the additional flow rate may be calculated in accordance with various conditions such as the angle of the boom 14 at the start of the up-and-down movement of the boom 14 and the operation amount of the boom operation lever 27.

Since it is not preferable to control the leveling cylinder 23 so that the working floor 21 converges while vibrating around the equilibrium state, the additional flow rate is such that the length of the leveling cylinder 23 exceeds the target length. The value is set so as not to shoot. It is preferable to limit the leveling flow rate as required, or to provide a limit so that the corrected hydraulic oil flow rate does not exceed a predetermined level.

FIG. 4 shows a change in the flow rate FU of hydraulic oil flowing into the up-and-down cylinder 16 when the boom operation lever 27 is stepped from the neutral position to start the up-and-down movement of the boom 14 and the leveling cylinder 23. 5A and 5B are graphs showing the change in the flow rate FL of the inflowing hydraulic oil and the change in the operation amount δ of the boom operation lever over time, and FIG. (C) is a change in the flow rate of the hydraulic oil flowing into the leveling cylinder. Here, a broken line in FIG. 4C indicates a change in the flow rate FL1 of the hydraulic oil flowing into the leveling cylinder 23 by supplying the leveling flow rate, and a dashed line flows into the leveling cylinder 23 by supplying the additional flow rate. This is a change in the flow rate FL2 of the hydraulic oil. As described above, the change in the flow rate of the working oil flowing into the leveling cylinder 23 is made closer to the change in the flow rate of the working oil flowing into the up-and-down cylinder 16, thereby changing the operation speed of the leveling cylinder 23 in accordance with the operation speed of the up-and-down cylinder 16. be able to. For this reason, the leveling of the work floor 21 can follow up and down of the boom 14 without delay. The time ΔT shown in the drawing represents a time (operation delay time) in which the operation start time of the leveling cylinder 23 is delayed with respect to the operation start time of the undulating cylinder 16 when no additional flow rate is added. I have.

As described above, in the above-described leveling device, the hydraulic oil flow rate (leveling flow rate) required to support the work floor 21 in an equilibrium state depends on the rise and fall of the boom 14 of the leveling cylinder 23 at the start of the rise and fall of the boom 14. Since the leveling cylinder 23 is operated with the corrected hydraulic oil flow rate that can suppress the operation delay, the leveling (balancing) of the work floor 21 at the start of the boom up / down does not delay the up / down of the boom 14.

In the leveling device having the above-described structure, unlike the above-described leveling device in which the upper and lower leveling cylinders are connected to a closed circuit by an oil passage, the operation of the leveling cylinder 23 is controlled by the controller 40 and the balance control valve 55. Even if a part of the oil passages 63 and 64 below the double holding valve 56 is broken, the balance control valve 55 is set to the neutral position to bring the ABT connection state. The leveling cylinder 23 can be hydraulically locked instantaneously to maintain the equilibrium state of the work floor 21.

Although the leveling device according to the present invention has been described above, the present invention is not limited to the configuration shown in the above embodiment. For example, as a method of setting the corrected hydraulic oil flow rate, in addition to the method of adding the additional flow rate to the leveling flow rate as in the above-described embodiment, a method of multiplying the leveling flow rate by a coefficient may be considered. Further, the supporting force of the leveling cylinder 23 can be obtained by calculation from the magnitude of the load acting on the work floor 21 and the load position.

[0028]

As described above, in the leveling device for an aerial work vehicle according to the present invention, the balance for maintaining the work floor in an equilibrium state by controlling the flow rate of the working oil supplied to the second hydraulic actuator. The control means activates the second hydraulic actuator at a corrected hydraulic oil flow rate that can suppress the operation delay of the second hydraulic actuator with respect to the boom up / down at the start of the boom up / down. Leveling does not fall behind the boom undulation. Also,
Unlike the leveling device which is configured by connecting the upper and lower leveling cylinders with an oil passage, the operation of the second hydraulic actuator can be directly controlled by the balance control means, so that the locking to the oil passage immediately below the second hydraulic actuator is performed. If a circuit (for example, the double holding valve 56 in the embodiment) is provided and the neutral position of the balance control valve is set to the ABT connection position, a part of the oil passage should be broken during operation of the second hydraulic actuator. However, by instantly switching the balance control valve to the neutral position, the second hydraulic actuator can be hydraulically locked to maintain the work floor in an equilibrium state.

Here, a supporting force detecting means (for example, a supporting force detector 46 in the embodiment) for detecting a supporting force of the second hydraulic actuator is provided, and the corrected hydraulic oil flow rate is detected by the supporting force detecting means. It is preferable that the setting is made in accordance with the magnitude of the supporting force of the second hydraulic actuator. According to such a configuration, the second
Irrespective of the supporting force of the hydraulic actuator, that is, the magnitude of the load applied to the work floor, accurate leveling can always be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a leveling device according to the present invention.

FIG. 2 is a side view of an aerial work vehicle equipped with the leveling device.

FIG. 3 is a block diagram for explaining a control system of the aerial work vehicle.

FIG. 4 shows a change in the flow rate of hydraulic oil flowing into the up-and-down cylinder and a change in the flow rate of hydraulic oil flowing into the leveling cylinder in a case where the boom operation lever is changed from the neutral position in a stepped manner, in accordance with the lever operation amount. It is a graph shown.

[Explanation of symbols]

REFERENCE SIGNS LIST 10 aerial work platform 11 body 14 boom 16 up / down cylinder (first hydraulic actuator) 21 work floor 23 leveling cylinder (second hydraulic actuator) 27 boom operating lever (up / down command means) 40 controller (up / down control means, balance control means) 51 Undulation control valve (undulation control means) 55 Equilibrium control valve (equilibrium control means)

Claims (2)

[Claims] 1. A vehicle body, a boom provided on the vehicle body so as to be able to move up and down, a work floor attached to a tip end of the boom so as to be able to swing up and down, a first hydraulic actuator which makes the boom move up and down, A second hydraulic actuator for vertically oscillating the work floor, an up / down command device for giving an up / down command for the boom by an external operation, and the first hydraulic actuator so as to raise / lower the boom in response to the operation of the up / down command device And an equilibrium control unit that controls the operation of the second hydraulic actuator so as to support the work floor in an equilibrium state in accordance with the ups and downs of the boom. The control means controls the flow rate of hydraulic oil supplied to the second hydraulic actuator to operate the second hydraulic actuator. The leveling of the aerial work vehicle, wherein, at the start of the boom up / down operation, the second hydraulic actuator is operated with a corrected hydraulic oil flow rate capable of suppressing an operation delay of the second hydraulic actuator with respect to the up / down operation of the boom. apparatus. 2. The method according to claim 1, further comprising: a supporting force detecting unit configured to detect a supporting force of the second hydraulic actuator, wherein the corrected hydraulic oil flow rate is a magnitude of the supporting force of the second hydraulic actuator detected by the supporting force detecting unit. 2. The leveling device for an aerial work vehicle according to claim 1, wherein the leveling device is set according to the following.