JPH0646947Y2 - Leveling device - Google Patents

Description

[Detailed Description of Device] a. Purpose of the Invention (Industrial Application Field) The present invention relates to an aerial work vehicle in which a work platform is attached to the tip of a boom that is installed on a cargo bed of an automobile so that it can be undulated or bent. The present invention relates to a leveling device that holds horizontally.

(Prior Art) As such a conventional leveling device, the operation of a leveling cylinder (work table swinging means) is controlled so that the work table becomes horizontal based on the detection of the undulation angle or flexion angle of the boom. Device (for example, the device disclosed in Japanese Utility Model Publication No. 64-1352), a device for detecting the deviation of the workbench from the horizontal level, and controlling the operation of the leveling cylinder.

(Problems to be solved by the invention) In all of these devices, when the boom is raised and lowered or bent and the workbench deviates from the horizontal level to some extent, it is detected, and the detected deviation is corrected. It is of the feedback control type. Further, since the minimum detection deviation (sensitivity) of the detector for detecting the deviation of the workbench is limited, the deviation cannot be detected unless the workbench deviates more than the sensitivity. Therefore, there is a problem that the leveling control is always performed after the operation of the boom, and the operation delay is particularly remarkable at the start and end of the boom operation.

In view of the above problems, it is an object of the present invention to provide a leveling device capable of performing leveling control of a work table without delay at the start and end of operation such as boom undulation.

B. Configuration of the Invention (Means for Solving the Problems) In order to achieve the above-mentioned object, in the present invention, an operation control signal of a boom operating means sent from an operating means (for example, an operating lever) in response to an operation of an operator. Is differentiated by a differentiator, and the computing unit corrects the deviation of the workbench detected by the deviation detector using the signal from the differentiator to calculate a correction deviation, and the leveling control means sets the correction deviation to zero. As described above, the operation of the workbench swinging means is controlled.

(Operation) In such a leveling device, for example, the detected deviation (deviation detected by the deviation detector) is corrected by the differential value of the operation control signal corresponding to the tilt angle of the operation lever to calculate the corrected deviation. That is, when the operation lever is operated, even if the detection deviation is 0 (horizontal level value), it is considered that the correction deviation has occurred, and the work table swings in the direction in which the correction deviation becomes zero. The means work. Therefore, the leveling control can be started without delay at the time of starting the operation of the boom. Also, when returning the operating lever to the neutral position (position to stop the boom), the detection deviation is similarly corrected, and the work platform swinging means operates based on the correction deviation. The leveling control can be ended.

(Embodiment) Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.

FIG. 2 shows an aerial work vehicle 1 equipped with a leveling device according to the present invention, and a body 1a of the aerial work vehicle 1 is mounted with an aerial work implement 2 rotatably. The aerial work machine 2 is a vehicle body
1a, which is rotatably attached to the base 4, a first boom 3a connected to the base 4 by pins 5a so as to rise and fall, and a second boom 3b which is extendable and retractable with respect to the first boom 3a. It also has a boom 3 and a workbench 6 connected to the tip of the second boom 3b so as to be swingable in the vertical direction by a pin 5b. A boom cylinder 7 is arranged between the first boom 3a and the base 4, and the boom cylinder 7 is controlled to expand and contract so that the first boom 3a and the second boom 3b are undulated about the pin 5a. , The undulation angle can be controlled. A leveling cylinder 11 is provided between the second boom 3b and the workbench 6, and the workbench 6 is pinned by controlling the expansion and contraction of the leveling cylinder 11.
Leveling control for maintaining the work table 6 in an equilibrium state can be performed by rotating the work table 6 around the center 5b.

A leveling device LA that performs this leveling control will be described with reference to FIG.

The leveling device LA includes an operating unit (operating means) 20, a leveling sensor (deviation detector) 30, a control unit 40,
It is composed of a leveling operation part (work table swinging means) 50.

The operation unit 20 is composed of an up-and-down operation lever 21 that is swingable in the left-right direction around the lower end, and a signal generator 22 attached to the lower end of the operation lever. The signal generator 22 is composed of a potentiometer and the like, and generates a signal of a current value according to the tilt angle of the operation lever 21. This signal becomes an operation control signal for controlling the operation of the undulating cylinder electromagnetic valve 60, which will be described later.

The leveling sensor 30 is attached to the workbench 6 and detects a deviation from the horizontal level of the workbench 6 (hereinafter, this deviation will be referred to as a detected deviation). This sensor 30 uses, for example, that a weight suspended like a pendulum of a clock inside the box moves the position inside the box due to gravity when the workbench 6 is inclined (deviation). It is configured to detect the deviation.

The control unit 40 includes a differentiator 41, a calculator 42, and a leveling controller (leveling control means) 43. The differentiator 41 is connected to the calculator 42 via a signal line, and the calculator 42 is similarly connected to the controller 43.

The leveling operating unit 50 is the same as the leveling cylinder 11 described above.
And a leveling cylinder electromagnetic valve 51 that controls the supply and discharge of hydraulic oil to and from the cylinder 11. The electromagnetic valve 51 is a three-position valve, and has an input port connected to the hydraulic pressure source OP, an extension side oil chamber 11a of the cylinder 11 and a shortening side oil chamber 1
It has two output ports each connected to 1b and a drain port connected to the tank T. In addition, the solenoid valve 51
Is a right-moving position (position for extending the cylinder 11), a left-moving position (position for shortening the cylinder 11) or a central position (hydraulic oil is removed by exciting or de-exciting the solenoids 51a, 51b attached to both sides of the valve body). It is located at a position where the tank T is drained. In addition, the solenoid valve 51 is a solenoid
This is a proportional control valve capable of controlling the flow rate of hydraulic oil flowing out from the output port depending on the magnitude of the exciting force of 51a and 51b.

The signal generator 22 is connected to the differentiator 41 via the operation control signal line 22a and to the solenoids 60a and 60b of the undulating cylinder solenoid valve 60 via the undulation signal line 22b. The solenoid valve 60 supplies and discharges hydraulic oil to and from the undulating cylinder 7, and its configuration is the same as that of the solenoid valve 51 for the leveling cylinder.

Further, the leveling sensor 30 is connected to the computing unit 42 via the detection signal line 30a.

In addition, the leveling controller 43 is
It is connected to the solenoids 51a and 51b via 43a.

Next, the operation of the device LA will be described.

When the operator falls the operating lever 21 from the position E (neutral position) shown in FIG. 3b to the position F, the signal generator 22 sends it to the solenoid 60a as the tilt angle of the operating lever 21 increases. The current value of the operation control signal increases. As this operation control signal increases the exciting force of the solenoid 60a, the amount of hydraulic oil supplied to the undulating cylinder 7 increases, and the extension operation of the undulating cylinder 7 becomes faster. Thus, in the process of falling operation of the operating lever 21,
The boom 3 stands up from the position A (actuation start position) shown in FIG. 3a to the position B while accelerating its actuation speed.

On the other hand, at this time, the operation control signal is differentiated by the differentiator 41 to be a differential signal, as shown in FIG. This differential signal becomes information about the operation of the boom 3 such as the operating direction and the operating speed. Further, the calculator 42 compares the detection signal from the leveling sensor 30 with a predetermined target value (for example, 0 indicating a horizontal level) to calculate a detection deviation.
Further, the computing unit 42 corrects this detection deviation with the differential signal to calculate the correction deviation. The leveling controller 43 moves the work table 6 in the direction (direction of arrow G) in which the correction deviation becomes zero.
In order to swing the solenoid valve 51, a leveling signal is sent to the solenoid 51b to switch the electromagnetic valve 51 to the left position. Thus, the hydraulic oil flows into the shortening side oil chamber 11b of the leveling cylinder 11, and the cylinder 11 is shortened. The leveling signal excites the solenoid 51b so that the swing speed of the workbench 6 corresponds to the operating speed of the boom 3.

While the operator holds the operation lever 21 in the F position,
The current value of the operation control signal is constant. Therefore, the boom 3 is erected at a constant speed from the position B to the position C. Further, during this period, the differential signal becomes 0, so that the leveling control is substantially performed only based on the detection deviation.

The boom 3 stands up to the position C, and the operator operates the operation lever.
When 21 is returned from the F position to the E position, the current value of the operation control signal decreases as the tilt angle of the operating lever 21 decreases. Therefore, the boom 3 stops at the position D while decelerating from the position C. During this time, boom 3 moves from A to B
Similarly to the case of standing up at the position of, the correction deviation is calculated by the differential signal of the operation control signal, and the leveling signal is sent to the solenoid 51b based on this. In this way, in response to the deceleration operation of the boom 3, the workbench 6 swings in the direction (G 'direction) in which the correction deviation becomes zero, and the leveling control of the workbench 6 is terminated when the boom 3 is stopped.

The leveling sensor 21 detects the deviation by utilizing gravity, and is affected by the acceleration (inertial force) generated when the boom 3 is raised and lowered. For example, as shown in FIG. 3a, the inertial force due to the acceleration from the start of the operation of the boom 3 until the predetermined operation speed is reached may shift the weight M from the vertical position indicated by the solid line to the position indicated by the dotted line M ′. . At this time, the leveling sensor 30 outputs an error detection signal indicating that the workbench 6 has deviated as shown by the dotted line 6 '. Therefore, the workbench 6 is swung in the direction opposite to the G direction, which should be originally swung. However, in this apparatus LA, this error detection deviation is corrected to suppress such swinging of the work table 6 in the opposite direction.

Further, instead of the leveling sensor 30 used in the apparatus LA, an angle sensor or the like that detects the undulation angle of the boom 3 may be used to calculate the deviation of the workbench 6 and use it as the detection deviation.

C. Effect of the Invention As described above, when the present leveling device is used, the operator can operate the operating means such as the operating lever to calculate the deviation of the workbench that can occur prior to the operation of the boom as the correction deviation. The leveling control is performed based on this correction deviation. Therefore, the leveling control can be started without delay at the time of starting the boom undulation or bending / extending operation, and the leveling control can be ended at the same time when the operation of the boom is ended.

[Brief description of drawings]

FIG. 1 is a schematic view showing the structure of a leveling device according to the present invention, FIG. 2 is a front view showing an aerial worker equipped with the leveling device, and FIG. 3a is a schematic view showing the operation of the leveling device. Fig. 3b is a schematic diagram showing the operation of the undulating operation lever, and Fig. 4 is a conceptual diagram showing the flow of signals in the leveling device. 3 …… Boom, 6 …… Workbench 11 …… Leveling cylinder 21 …… Release control lever, 22 …… Signal generation period 41 …… Differentiator, 42 …… Calculator 43 …… Leveling controller

Claims (1)

[Scope of utility model registration request] 1. An aerial work vehicle equipped with a work platform which is vertically swingable at the tip of a boom that can be undulated or bent.
A leveling device for horizontally holding the workbench, comprising a workbench swinging means for vertically swinging the workbench, a deviation detector for detecting a deviation from a horizontal level of the workbench, and the boom Boom work means for ups and downs and bending, operation means for sending an operation control signal of the boom operation means according to an operation of an operator, a differentiator for differentiating the operation control signal, and a signal from the differentiator. It is characterized by comprising an arithmetic unit for correcting the deviation detected by the deviation detector and calculating a correction deviation, and a leveling control means for controlling the work table swinging means so as to make the correction deviation zero. And leveling device.