JP2002255495A - Load detector of vehicle for high lift work - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exactly detect load of a workbench in a vehicle for high lift work provided with an extensile-contractile link mechanism at a leading end of a boom. SOLUTION: At the leading end of the boom 5 placed on a vehicle body in at least a free derricking manner, the extensive-contractive link mechanism 20 is pivotally mounted to be swingable in a vertical plane, and at a leading end of the extensive-contractive link mechanism 20, the workbench 9 supported horizontally independently from a hoisting angle of the boom 5 is paced, thereby constituting a boom type vehicle for high lift work. The load detector comprises an extensive-contractive angel detector 33 for detecting an extensive-contractive angle of the extensive-contractive link mechanism 20; and a pressure detector 35 for detecting an operation pressure of an extending-contracting cylinder 21 in the extensive-contractive link 20. In this load detector, the load of the workbench 9 is calculated from the extensive-contractive angle of the extensive- contractive link mechanism 21 detected by the extensive-contractive angel detector 33, and the value of the operation pressure of the extending-contracting cylinder 21 detected by the pressure detector 35.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load detecting device for an aerial work vehicle having a bending and stretching link mechanism.

[0002]

2. Description of the Related Art Generally, an aerial work vehicle is constructed by attaching a work table to the end of a boom, and sometimes it is required to detect a load acting on or mounted on the work table. For example, in order to ensure safety when working at heights, to prevent the overturning moment acting on the vehicle body from being excessively increased according to the movement of the worktable and to prevent the stability from being reduced,
An overturn prevention device may be provided, but a workbench load may be used in the overturn prevention device, and this will be briefly described.

As a fall prevention device, a device for detecting the actual moment acting on the vehicle body in the overturn direction at the time of work and restricting the movement of the work table (operation of the boom) so that the moment is equal to or less than an allowable moment (a moment regulating device and a moment regulating device). Called)
Alternatively, a moment acting on the vehicle body with respect to the moving position of the worktable is calculated in advance, and a moving range of the worktable (allowable work range) in which this moment does not exceed the allowable moment is set. There is a device (referred to as a work range control device) that restricts the work table from moving beyond the allowable work range.

[0004] In the working range control device, an allowable working range is set so that the allowable moment does not exceed the allowable moment when a rated load (allowable maximum load) is applied to the worktable from the viewpoint of safety. For this reason, when the load on the workbench is equal to or less than the rated load, there is a problem in that an allowable work range based on the rated load is set, although work within a larger work range may actually be allowed. Here, if the actual load on the workbench is known, it is possible to set a wider allowable working range so as not to exceed the allowable moment with respect to the actual load, thereby improving the efficiency of working at a high place. It is required to detect the actual load on the worktable.

[0005] Further, the rated load of the worktable is the strength of the boom,
It is set from the viewpoint of safety, etc., and it is not desirable to work at heights with a load greater than the rated load acting on the platform, and it is necessary to detect whether the platform load is within the rated load. Is often required, and even in such a case, it is required to detect the actual load on the work table.

In view of the above, conventionally, a moment acting on the vehicle body from a boom, a worktable, or the like is obtained from the operating pressure of an up / down cylinder for performing the up / down operation of the boom and the up / down angle of the boom. The load on the workbench was detected in comparison with the moment at the time.

[0007]

However, when the moment is detected in this manner, variations in the weight of the boom itself, detection errors in the undulation angle, and calculation errors due to expansion and contraction of the boom accumulate, and the work platform load is reduced. There is a problem that the detection accuracy is not very good.

The present invention has been made in view of such a problem.
An object of the present invention is to provide a load detection device for an aerial work vehicle that can accurately detect a load on a workbench attached to the end of a bendable / extend link mechanism in an aerial work vehicle having a bendable / extendable link mechanism at the end of a boom. And

[0009]

In order to achieve the above object, according to the present invention, a bending / extending link mechanism is swingably movable in a vertical plane at the end of a boom provided at least on a vehicle body so as to be able to move up and down. A boom type aerial work vehicle is provided that has a worktable that is pivotally mounted and horizontally supported at the tip of the bending and stretching link mechanism regardless of the boom angle. A bending / extension angle detector for detecting the bending / extension angle of the bending / extension link mechanism, and an axial force detector for detecting an axial force acting on the bending / extension cylinder in the bending / extension link mechanism (for example, the pressure detector in the embodiment of the invention) And a pin-type load cell) constitute a load detector.
In this load detector, the load on the workbench is detected from the bending / extension angle of the bending / extension link mechanism detected by the bending / extension angle detector and the value of the axial force of the bending / extension cylinder detected by the axial force detector.

In the load detection of the aerial work vehicle having such a configuration, the load on the work table is detected based on the bending / extension angle of the bending / extension link mechanism and the operating axial force of the bending / extension cylinder, and a boom to which the bending / extension link mechanism is attached. Workbench load is determined without being affected by the weight, undulation angle, etc. For this reason, there is no danger that the accuracy of the detection will be reduced due to the accumulation of the variation in the weight of the boom itself, the detection error of the undulation angle, the calculation error due to the expansion and contraction of the boom, etc., as in the related art, and the load can be detected with high accuracy. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an aerial work vehicle 1 having a bending and stretching link mechanism 20 according to the present invention. The aerial work vehicle 1 can travel with front and rear wheels 3a and 3b, and is configured based on a truck vehicle having a driving cabin 2a at a front portion. A swivel 4 that is driven by a swivel motor (hydraulic motor) (not shown) so as to be able to swivel horizontally is disposed on the body 2 of the truck vehicle. A base end is pivotally connected to the swivel base 4 and a boom 5 is attached thereto. The boom 5 is raised and lowered by a lifting cylinder 6. The boom 5 is configured such that a base end boom 5a, an intermediate boom 5b, and a boom 5c are nestedly combined and can be extended and retracted by a built-in cylinder 7.

FIG. 2 shows the distal end side of the boom 5, that is,
The configuration of the bending / extending link mechanism 20, the fixing member 8, and the worktable 9 is shown in an enlarged manner. The distal end boom 5c has a boom head 5d at the distal end, and the bending / extension link mechanism support member 12 is swingably attached to the boom head 5d. A bending and stretching link mechanism 20 having a bending and stretching cylinder 21 is attached to the distal end of the bending and stretching link mechanism support member 12 so as to be vertically swingable.

The bending / extending link mechanism 20 has two link members 23, 23 which are respectively connected to the bending / extending link mechanism support member 12 and extend in parallel with each other.
A bending / extending link mechanism tip member 25 is pivotally connected to the tips of the members 3, 23, and these members 21, 23, 23, 25 form a parallel link. Because of the parallel link function, the bending / extending link mechanism tip member 25 maintains the parallel positional relationship with the bending / extending link mechanism support member 12 regardless of the bending of the two link members 23,23. In the bending / stretching link mechanism 20, the bending / stretching cylinder 21 includes a support member 24 having a base end pivotally connected to the bending / stretching link mechanism support member 12 and a distal end fixed to an upper link member 23.
When the bending / stretching cylinder 21 is extended and contracted, as shown in FIG.
The bending and stretching operation can be performed while maintaining the position of the member 3 in parallel.

A vertical post 8 is fixed to the distal end of the bending / extending link mechanism distal member 25, and the vertical post 8 is swung together with the bending / extending link mechanism distal member 25. On the other hand, a leveling cylinder 11 is provided between the boom head 5d and the bending / extension link mechanism support member 12, and the leveling cylinder 11 controls the swinging of the bending / extension link mechanism support member 12, so that the elevation angle of the boom 5 is adjusted. Regardless, the bending / extension link mechanism support member 12 is held at a predetermined swing position. Here, since the bending / extension link mechanism tip member 25 to which the vertical post 8 is fixed by the bending / extension link mechanism 20 is maintained in a parallel positional relationship with the bending / extension link mechanism support member 12, the leveling cylinder 11 has the vertical post portion 8 always vertical. The swing control of the bending and stretching link mechanism support member 12 is performed so as to extend to the position.

As described above, the work table 9 is attached to the vertical post portion 8 which is always held vertically irrespective of the ups and downs of the boom 5 so that the work table 9 can be swiveled horizontally (to swing freely).
Is held horizontally irrespective of the elevation angle of the boom 5 and the flexion / extension angle of the flexion / extension link mechanism 20.

As shown in FIG. 1, four outriggers 10 are provided at the front, rear, left and right of the vehicle body 2 so as to be extendable and contractible downward. The vehicle body 2 can be lifted and supported.

Next, the configuration and operation of the load detecting device for aerial work vehicles according to the present invention will be described with reference to FIG. For this load detection, the bending / extension angle of the bending / extension link mechanism 20 is detected by a bending / extension angle detector 33 composed of a potentiometer and the like, and the swing angle of the work table 9 is similarly detected by a pivot angle detector 34 composed of a potentiometer and the like. The operating pressure of the bending / stretching cylinder 21 is detected by the pressure detector 35. These detection signals are sent to the controller 30, where the moment acting on the bending / extension link mechanism 20 from the work table 9 based on the bending / extension angle and the operating pressure (this is referred to as a total moment M0) is calculated. This calculation is performed by obtaining the axial direction of the bending and stretching cylinder 21 based on the bending and stretching angle, and calculating the axial force acting in this axial direction from the operating pressure. The total moment M0 obtained in this manner is the weight of the work table 9 , The moment generated by the mounting load of the worktable 9 and the own weight of the bending and stretching link mechanism 20.

Since the length of the bending / extending link mechanism 20 (the length of the link members 23, 23) is constant, the weight and the position of the center of gravity of the bending / extending link mechanism 20 can be obtained in advance. If the bending / extension angle is known, a moment generated based on the weight of the bending / extending link mechanism 20 (this is called a link mechanism moment M1) can be calculated. Similarly, the own weight of the work table 9 can be obtained by measuring or calculating in advance, and if the bending angle of the bending and stretching link mechanism 20 and the swing angle of the work table 9 are known, the position of the work table 9 can be obtained. The moment generated based on the weight of the workbench 9 (this is referred to as the workbench own weight moment M2) can be calculated.

In the controller 30, based on detection signals from the bending / extension angle detector 33, the swing angle detector 34 and the pressure detector 35, the total moment M0,
The link mechanism moment M1 and the work platform own weight moment M2 are calculated. Further, the load moment M3 is obtained by subtracting the link mechanism moment M1 and the work platform own weight moment M2 from the total moment M0 (M3 = M
0-M1-M2). The load moment M thus obtained
Reference numeral 3 denotes a moment generated by the mounting load of the work table 9, and the load of the work table 9 can be accurately calculated from the load moment M3 using the bending / extension angle at that time.

The mounting load of the work table 9 obtained in this way is used for work range regulation, and an optimum and maximum allowable work range according to this mounting load is set to perform efficient work at a high place. Becomes possible. Specifically, a plurality of allowable work ranges corresponding to the load are set and stored in the memory 31 in advance, and the allowable work range corresponding to the actual load of the work table 9 obtained as described above is read out. When the operator 9 attempts to move beyond the read allowable work range, the work table 9 moves beyond the allowable work range by, for example, regulating the operation of the boom 5 by a control valve 40 for controlling the operation of the boom 5 or the like. And ensure safety. When the movement of the work table 9 is regulated in this way, an alarm operation by the alarm device 38 (an alarm operation by a buzzer, a lamp, or the like) is performed.

If the mounting load is obtained as described above, when a load exceeding the rated load is mounted on the work table 9, it can be easily detected. In such a case, the alarm 38 can be used to give an alarm. By controlling the operation by the control valve 40, work at a high place in a state where a load exceeding the rated load is mounted is regulated, and the safety of the work is ensured.

It is to be noted that there is also a method of detecting whether or not the work table 9 is mounted above the rated load without directly calculating the load on the work table 9 as described above. This will be described below. FIG. 4 shows the bending and stretching cylinder 2 according to the bending and stretching angle of the bending and stretching link mechanism 20 when the rated maximum loading weight is mounted on the work table 9.
1 shows the change of the operating pressure within 1 (this is called the maximum allowable pressure). If the operating pressure of the bending / stretching cylinder 21 detected by the pressure detector 35 is equal to or less than the maximum allowable pressure corresponding to each bending / extension angle shown in this drawing, the mounting load of the work table 9 is equal to or less than the rated load. Therefore, the memory 3 in FIG.
In FIG. 1, the relationship shown in FIG. 4 is stored in advance, and the controller 30 reads this relationship from the memory 31 and determines whether the operating pressure detected by the pressure detector 35 is equal to or less than the maximum allowable pressure. When the operating pressure exceeds the maximum allowable pressure, it can be determined that a load equal to or greater than the rated load is mounted on the work table 9, so that an alarm is issued by the alarm 38, and the operation is restricted by the control valve 40. At the same time, work at heights with a load exceeding the rated load is regulated to ensure work safety.

In the above embodiment, the pressure detector 35
Although the operating pressure of the bending / extension cylinder 21 is detected and the axial force acting in the axial direction of the bending / extension cylinder 21 is obtained from this pressure, the axial force may be obtained directly by a direct pin type load cell or the like.

Further, in the aerial work vehicle described above, a device is devised so that control and maintenance of the bending / extending link mechanism can be easily performed. For example, in the case of replacing parts when the load detecting device fails, high convenience can be obtained such that conventionally, lifting a boom exceeding 1 t only requires lifting the bucket work table alone. In addition, in the adjustment and inspection of the load detection device, in the past, it was necessary to look into the swivel base, go under the boom, and remove the boom, but all of these were from the side of the bending and stretching link mechanism. It can be configured so that it can be done by the approach, which is extremely simple.

In addition, if the load on the workbench 9 is detected, the relationship between the bending and stretching angle at this time and the operating pressure of the bending and stretching cylinder 21 (the relationship as shown in FIG. 4) can be obtained. It can be determined whether or not the hydraulic cylinder 21 for bending and extension is near the stroke end based on the operating pressure of the cylinder 21 for bending and stretching. Therefore, when the bending / stretching cylinder 21 is located near the stroke end, it is possible to control the operation speed to be slow to reduce the shock at the stroke end. Also, when the work table 9 is pressed against the ground or a building or the like by the operation of the boom 5 and the operation of the bending and extension link mechanism 20, the bending and stretching cylinder 21 is pressed.
This can be detected from the change in the hydraulic pressure of the motor, and control for preventing the pressing can be performed. By doing so, the overload relief valve (overload control valve) for the up / down cylinder and the bending / extending cylinder can be eliminated, and the configuration of the hydraulic control device can be simplified.

[0026]

As described above, according to the present invention,
The load on the workbench is detected based on the bending / extension angle of the bending / extension link mechanism and the operating pressure of the bending / extension cylinder. For this reason, there is no danger that the accuracy of the detection will be reduced due to the accumulation of the variation in the weight of the boom itself, the detection error of the undulation angle, the calculation error due to the expansion and contraction of the boom, etc., as in the related art, and the load can be detected with high accuracy. .

[Brief description of the 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 an enlarged front view showing the periphery of a bending and stretching link mechanism of the aerial work vehicle;

FIG. 3 is a block diagram showing a configuration of a load detector and an operation controller based on the load detector.

FIG. 4 is a graph showing the relationship between the bending and stretching angle and the operating pressure in a bending and stretching cylinder when a rated load is mounted on a workbench.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Height working vehicle 4 Revolving base 5 Boom 6 Undulating cylinder 7 Telescopic cylinder 8 Vertical post 9 Workbench 11 Leveling cylinder 12 Bending and stretching link mechanism support member 20 Bending and stretching link mechanism 21 Bending and stretching cylinder 25 Bending and stretching link mechanism tip member 33 Bending and stretching angle detector 35 Pressure detector

Claims (1)

[Claims] 1. A bending / extension link mechanism is pivotally mounted on a tip end of a boom provided at least on a vehicle body so as to be movable up and down so as to be swingable in a vertical plane. A load detector for an aerial work vehicle having a work table supported in a horizontal direction, wherein a bending / extension angle detector for detecting a bending / extension angle of the bending / extending link mechanism; and a shaft acting on a bending / extending cylinder in the bending / extending link mechanism. An axial force detector for detecting a force in the direction, and a bending and stretching angle of the bending and stretching link mechanism detected by the bending and stretching angle detector and an axial force acting on the bending and stretching cylinder detected by the axial force detector. A load detection device for the aerial work vehicle, wherein the load on the workbench is detected from the value of the work table.