JPH0546897U - Load detection device for aerial work vehicles - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] It is not necessary to support the workbench of an aerial work platform with a spring for detecting the limit load, and the workbench load can be accurately measured regardless of the swing position of the workbench. To detect. [Structure] In an aerial work vehicle having a work platform which is always horizontally held by a vertical leveling cylinder on a hoisting telescopic boom, a boom hoisting angle detector 21, a vertical leveling cylinder supporting force detector 23, 24, a boom hoisting cylinder supporting force detector 25, which corresponds to the hoisting angle of the boom, and corresponds to the hoisting angle of the boom, the moment M1 of the workbench due to the force supporting the upper leveling cylinder, the moment M2 of the boom due to the force supporting the lower leveling cylinder, It has a calculator for calculating the moments M3 and M0 of the boom due to the weight of the boom itself, and further calculates and detects the load W of the workbench from the following equation. W = (M3 + M2-M1-M0) / R However, R: Horizontal distance from the boom hoisting center to the platform swing center.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a device for calculating and detecting the load of a workbench in an aerial work vehicle having a workbench at the tip of a boom that can be undulated, extended and retracted.

[0002]

[Prior Art]

 In an aerial work vehicle that has a work platform on which an operator can ride at the tip of a boom that can be undulated and expanded and contracted, etc., in the falling direction that is applied to the vehicle body in accordance with changes in the boom undulation angle and extension amount, Since the moment changes, it has been conventionally known that the moment is regulated so as to prevent the boom from undulating and expanding and contracting so that the moment does not exceed a predetermined value. Such a moment in the falling direction changes not only according to the hoisting angle of the boom, the amount of extension, etc., but also due to the load on the workbench (the weight of the workbench and the load on the workbench). Therefore, it is necessary to regulate the moment.

From the above, the load on the workbench has been taken into consideration even in the conventional moment regulation. For example, a workbench is attached to the tip of the boom via a spring so that the spring flexes according to the load on the workbench so that the workbench moves up and down. There is a limit switch at the lower position. In this case, the limit switch is turned on when the load on the work table exceeds the limit load, and the moment is regulated accordingly.

[0004]

[Problems to be solved by the device]

 However, in the case of this aerial work vehicle, since the workbench is supported by the spring, the workbench moves up and down, which gives an uncomfortable feeling to the worker who has boarded the workbench, and the ride comfort is low. There is a problem that it is not so good. Also, if an inertial force is applied to the worktable during boom operation, etc., the amount of spring deflection increases due to this inertial force, and the limit switch turns on even though the worktable load is within the limits. There is also a problem that there are things to do.

On the other hand, Japanese Patent Publication No. 14640/1989 discloses an upper leveling cylinder disposed between a workbench and a boom, a lower leveling cylinder disposed between the boom and a vehicle body, and both leveling cylinders. Aerial work vehicle that has an oil passage that connects the oil chambers of the above and has a leveling device that expands and contracts the upper leveling cylinder according to the expansion and contraction of the lower leveling cylinder due to the ups and downs of the boom, and keeps the work table horizontal. Discloses a device that detects the moment applied to the vehicle body from the axial load of the lower leveling cylinder and the axial load of the undulating cylinder, and compares this with the allowable moment to regulate the moment. In the case of this device, it is not necessary to support the workbench with a spring, and the above problem does not occur.

However, in the case of this device, when the work table is horizontally swung, the position of the center of gravity of the work table moves, so the detected moment changes. For this reason, for example, when the workbench is swung toward the inner side of the vehicle body, the detected moment is reduced, and the allowable movement range (work range) of the workbench is widened. However, if the workbench is moved to the limit of the work range in such a widened state and then the workbench is swung toward the outer side of the vehicle body, the detected moment is increased this time, and the moment regulation works. However, there is a problem that the swinging motion is restricted, and if it is left as it is, the swinging motion cannot be performed. In addition, after this, in order to swing the head, it is necessary to raise and lower the boom, extend and retract, etc. to move the work table inward to reduce the detection moment.In the case of this device, it is easy to use. There is a problem that is not good.

The present invention has been made in view of the above problems, and in an aerial work vehicle, it is not necessary to support the work platform with a beam, and the work platform can be attached to the tip of the boom. An object of the present invention is to provide a load detection device capable of accurately detecting a workbench load regardless of the swinging motion of the work.

[0008]

[Means for Solving the Problems]

 In order to achieve such an object, the load detecting device according to the present invention has a boom mounted on the vehicle body at least so that it can be raised and lowered, and a work platform attached to the tip of the boom is constantly leveled by a leveling device. In an aerial work vehicle that has been kept in place, the hoisting angle detector that detects the hoisting angle of the boom, the first support force detector that detects the support force of the upper leveling cylinder, and the support of the lower leveling cylinder. It has a second supporting force detector for detecting the force and a third supporting force detector for detecting the supporting force of the undulating cylinder. This load detecting device further corresponds to the hoisting angle of the boom detected by the hoisting angle detector, and the supporting force of the upper leveling cylinder detected by the first supporting force detector causes it to move around the swing center of the workbench. The first moment M1 that is generated, the second moment M2 that is generated around the undulating center of the boom due to the support force of the lower leveling cylinder that is detected by the second support force detector, and the third moment that is detected by the third support force detector It has a calculator that calculates the third moment M3 generated around the center of the hoisting motion of the boom due to the supporting force of the hoisting cylinder, and the moment M0 of own weight occurring around the center of the hoisting motion of the boom due to the weight of the boom. In the vessel, the following formula W = (M3 + M2-M1-M0) / R (where R: horizontal distance from the center of hoisting of the boom to the center of swinging of the workbench) Ri has become the platform of the load W to be calculated detection.

[0009]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. An example of an aerial work vehicle having a load detection device according to the present invention is shown in FIG. This aerial work vehicle has a swivel base 2 which can swivel on a vehicle body 1, and a telescopic boom 3 is attached to the swivel base 2 in an undulating manner. The telescopic boom 3 is composed of a base boom 3a which is pivotally supported by a swivel base 2 by a pin 5 so as to be up and down, and a tip boom 3b which is telescopic with respect to the base boom 3a. The tip boom 3b is extended and retracted by the extended telescopic cylinder (not shown). The hoisting operation of the extension boom 3 is performed by the hoisting cylinder 4 that is pivotally supported by the pins 4a and 4b between the swivel base 2 and the base end boom 3a.

A support post 6 is attached to the tip of the tip boom 3b so as to be pivotally supported by a pin 3c so as to be vertically swingable. A workbench 7 is attached to the vertical post portion 6a of the support post 6 so as to be horizontally rotatable around the vertical post portion 6a. For this reason, the workbench 7 can swing up and down together with the support post 6 about the pin 3c, and can swing horizontally in the horizontal direction about the vertical post 6a. Outriggers 8 are attached to the front, rear, left, and right of the vehicle body 1 to extend and support the vehicle body 1 during work.

Since an operator rides on the workbench 7, it is necessary to keep the workbench 7 always horizontal regardless of the ups and downs of the telescopic boom 3. For this reason, this aerial work vehicle is equipped with a leveling device including a lower leveling cylinder 11 and an upper leveling cylinder 12. As shown in FIG. 1, the lower leveling cylinder 11 is pivotally supported by pins 11a and 11b between the swivel base 2 and the base boom 3a, and the upper leveling cylinder 12 supports the tip boom 3b. It is supported and disposed between the post 6 and the pins 6 by pins 12a and 12b.

The bottom-side oil chambers of the lower leveling cylinder 11 and the upper leveling cylinder 12 communicate with each other, and the rod-side oil chambers of the lower leveling cylinder 11 and the upper leveling cylinder 12 communicate with each other. For this reason, for example, when the telescopic boom 3 is hoisted by the hoisting boom 3 and the lower leveling cylinder 11 is telescopically operated, the upper leveling cylinder 12 is telescopically operated in the opposite direction to the lower leveling cylinder 11, and the posture of the workbench 7 is increased. Is always held horizontally.

According to the present invention, the aerial work vehicle having such a structure is provided with a load detection device for calculating the load of the work table 7, that is, the total value of the weight of the work table 7 and the loaded load thereof. Has been. The configuration of this load detecting device is shown in FIG. This device includes a hoisting angle sensor 21 for detecting the hoisting angle of the telescopic boom 3, an extension amount sensor 22 for detecting the extension amount of the telescopic boom 3 (extension amount of the tip side boom 3b), and a support for the upper leveling cylinder 12. A first supporting force detector 23 that detects the force F1, a second supporting force detector 24 that detects the supporting force F2 of the lower leveling cylinder 11, and a third supporting force that detects the supporting force F3 of the undulating cylinder 4. And a detector 25.

The first to third supporting force detectors 23, 24, 25 are composed of load cells arranged on the support pins 12 a, 11 a, 4 a of the cylinders 12, 11, 4 respectively, or the cylinders 12, 22 are respectively arranged. , 4 are composed of oil pressure sensors that detect the internal oil pressure. In the case of a load cell, each supporting force is directly detected, and in the case of a hydraulic sensor, each supporting force is calculated and detected from the cylinder pressure receiving area and the detected hydraulic pressure.

The load detection device has a calculator 30 that performs various calculations based on the detection values from the five sensors and the detectors 21 to 25. The calculator 30 calculates a radius R (see FIG. 1) from the center of hoisting and retracting the telescopic boom 3 (pin 5) to the center of vertical swing of the workbench 7 (swing center, that is, the pin 3c). A calculation unit 31, a moment calculation unit 32 that calculates the moments M1 to M3 generated by the supporting forces F1 to F3, and a self-weight moment reading unit 33 that reads out a moment M0 due to the self-weight of the telescopic boom 3 from a table stored in advance. , A workbench load calculator 34 that calculates the load W of the workbench 7 from the radius R and the moments M1 to M3 and M0.

The radius R calculated by the radius calculation unit 31 differs depending on the hoisting angle and the amount of extension of the telescopic boom 3. Therefore, the radius calculation unit 31 detects the radius R detected by the hoisting angle sensor 21 and the extension amount sensor 22. A signal is input, and the radius R at that time is calculated in the radius calculation unit 31 based on the undulation angle and the extension amount. In addition, since the self-weight moment of the telescopic boom 3 generated around the hoisting operation center (pin 5) due to the self-weight of the telescopic boom 3 also differs depending on the hoisting angle and extension amount of the telescopic boom 3, the self-weight moment reading unit 33 also has the hoisting angle. Detection signals from the sensor 21 and the extension amount sensor 22 are input. The reading unit 33 has a table in which the self-weight moment is stored corresponding to the hoisting angle and extension amount of the telescopic boom 3, and the self-weight corresponding to the detection signals from both sensors 21, 22 in the reading unit 34. The moment M 0 is read from this table.

In the moment calculator 32, the first to third moments M1 to M3 are calculated. The first mameton M1 is a moment generated around the vertical swing center (pin 3c) of the work table 7 by the supporting force F1 of the upper leveling cylinder 12, and as shown in FIG. From the distance d1 from 3c, it is obtained by the following equation (1). M1 = F1 × d1 (1) The second mometon M2 is the moment generated around the undulating center (pin 5) of the telescopic boom 3 due to the supporting force F2 of the lower leveling cylinder 11, and in FIG. As shown, it is obtained from the following equation (2) from the distance d2 between the pin 5 and the axis of the lower leveling cylinder 11. M2 = F2 × d2 (2) Third moment M3 is a moment generated around the oscillating center (pin 5) of the telescopic boom 3 due to the supporting force F3 of the oscillating cylinder 4, as shown in FIG. From the distance d3 between the axis of the undulating cylinder 4 and the pin 5, the following equation (3) is used. M3 = F3 × d3 (3) Since the respective distances d1, d2, d3 change according to the hoisting angle of the telescopic boom 3, the detection signal from the hoisting angle sensor 21 is sent to the moment calculator 32. The distances d1, d2 and d3 are calculated based on the detected undulation angle.

The radius R, the self-weight moment M0, and the first to third moments M1 to M3 obtained as described above are sent to the workbench load calculation unit 34, and the workbench load W is calculated here. It This calculation will be described. In this aerial work vehicle, the undulating cylinder 4 and the lower leveling cylinder 11 support the moment Ma that acts on the vehicle body due to the dead weight of the telescopic boom 3 and the load of the workbench 7 (the deadweight of the workbench and the load). ing. Therefore, the moment M b due to the supporting force of the undulating cylinder 4 and the supporting force of the lower leveling cylinder 11 is balanced with the moment Ma.

Here, first, the moment Ma is the moment M4 (= W × R) generated when the weight W of the telescopic boom 3 and the load W of the workbench 7 act around the pin 5 separated by a radius R. ) And the first moment M1 around the pin 3c 2 generated by the supporting force of the upper leveling cylinder 12 is expressed by the following equation (4). Ma = M0 + M4 + M1 = M0 + W × R + F1 × d1 (4) On the other hand, the moment Mb is represented by the following equation (5) as the sum of the second and third moments M2 and M3. Mb = M2 + M3 = F2 × d2 + F3 × d3 (5)

Here, since Ma = Mb, the loads W on the workbench 7 are calculated by the following equation (6) by substituting the equations (4) and (5). W = (M3 + M2-M1-M0) / R (6) As described above, in the workbench load calculator 34, the load W of the workbench 7 is calculated by the equation (6).

The calculation result is output from the calculator 30 to the controller 40 and used for controlling the moment. The moment regulation in this example is performed assuming that the workbench load W is equal to or less than the maximum allowable load. Therefore, when the load W calculated as described above becomes equal to or more than the maximum allowable load, the alarm buzzer 45 is sounded and an overload alarm is issued to prevent the operation in such a state. Is becoming For this reason, in the case of the aerial work vehicle of this example, the work load is always kept below the maximum allowable load, and the moment regulation is also based on the assumption that the work load is less than the maximum allowable load. Done. For this reason, the moment can be restricted within a range where there is no problem even if the swinging operation of the work table 7 in the horizontal direction is performed, and this swinging operation can be freely performed, which is convenient.

[0022]

[Effect of the device]

 As described above, according to the present invention, the support force of the upper leveling cylinder detected by the first support force detector generates the first moment M1 and the second support force around the swing center of the workbench. The second moment M2 generated around the hoisting center of the boom due to the supporting force of the lower leveling cylinder detected by the detector, and the hoisting center of the boom due to the supporting force of the hoisting cylinder detected by the third supporting force detector. It has a computing unit that computes the third moment M3 that is generated around and the moment of gravity M0 that is generated around the undulating center of the boom due to the weight of the boom. In this computing unit, the following formula W = (M3 + M2- M1-M0) / R (however, R: horizontal distance from the hoisting center of the boom to the swing center of the work table) to calculate the work load W. , It is possible to accurately detect the loading weight of regardless worktable in a horizontal direction of the swing of the workbench. Therefore, it is possible to issue an overload warning and perform safe moment regulation.

Further, in the case of the present invention, since it is not necessary to support the workbench by the spring, the workbench does not move up and down so that the operator on the workbench does not feel uncomfortable. Furthermore, since the load on the workbench can be accurately determined and the moment can be regulated based on this, it is possible to prevent the momentum from acting in accordance with the horizontal swing motion of the workbench, as in the past. It can be prevented.

[Brief description of drawings]

FIG. 1 is a front view showing an aerial work vehicle having a load detection device according to the present invention.

FIG. 2 is a system diagram showing a configuration of the load detection device.

[Explanation of symbols]

 2 swivel base 3 telescopic boom 4 hoisting cylinder 6 support post 7 worktable 11, 12 leveling cylinder 30 calculator 45 alarm buzzer

Claims (1)

[Scope of utility model registration request] 1. A boom mounted on a vehicle body so as to be capable of hoisting, a hoisting cylinder for hoisting and operating the boom, a work platform mounted at the tip of the boom at least vertically swingably, and the work platform. And an upper leveling cylinder arranged between the boom and the boom, a lower leveling cylinder arranged between the boom and the vehicle body, and an oil passage connecting the oil chambers of these both leveling cylinders to each other. A load detecting device for an aerial work vehicle, comprising: Angle detector for detecting the undulation angle of the upper leveling cylinder, a first supporting force detector for detecting the supporting force of the upper leveling cylinder, and the lower leveling A second supporting force detector for detecting the supporting force of the cylinder, and a third supporting force detector for detecting the supporting force of the hoisting cylinder, and the hoisting angle of the boom detected by the hoisting angle detector Correspondingly, a first moment M1 generated around the swing center of the work table by the supporting force of the upper leveling cylinder detected by the first supporting force detector, and the second moment
The second moment M2 generated around the hoisting motion center of the boom by the supporting force of the lower leveling cylinder detected by the supporting force detector, and the supporting force of the hoisting cylinder detected by the third supporting force detector. A computing unit for computing a third moment M3 generated around the hoisting motion center of the boom and a self weight moment M0 occurring around the hoisting motion center of the boom due to the weight of the boom itself is provided. Furthermore, the moment M1,
Using M2, M3, M0, the following formula W = (M3 + M2-M1-M0) / R A load detecting device for an aerial work vehicle, wherein the load W is calculated and detected.