JPS6339517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a crane overload detection system for detecting basic data for detecting overload caused by the dead weight of a boom in a truck crane and the lifting load lifted by the boom. The present invention relates to a basic data detection device.

Traditionally, lifting machines such as cranes have
It is common knowledge to install safety equipment.
It is also essential for preventing accidents. Particularly in mobile cranes such as truck cranes, the overhanging support legs or wheels of the crane are not fixed to the work area, and, for example, the overhanging support legs ( These outriggers (hereinafter referred to as outriggers) substantially increase the ground contact area and prevent the crane from tipping over. However, there is a natural limit to the amount that the outriggers can protrude, so it is necessary to constantly monitor the usage status of the crane. As such a crane safety device, conventional cranes are equipped with load sensors and angle detection sensors, which measure the moment that acts when the crane is tilted [(lifted load on the boom) x (horizontal distance between the load and the crane)] There is a so-called moment limiter that calculates this and issues a warning when the crane is in danger of tipping over.

In addition, there are methods that measure only the lifting load and use the specialized knowledge and experience of the crane operator to determine whether the load is excessive or whether the crane is likely to fall. Although this device described below is clearly inadequate, the previously described device also suffers from several problems.

In other words, in the conventional truck crane moment limiter, the load sensor is connected to the rope, jib,
It is installed in parts such as elevating cylinders. For example, if it is installed in a jib part, different load detection methods are used for cranes with a fixed jib length and cranes whose jib length changes by expanding and contracting. Moreover, when measuring the rope tension of a suspended load directly or indirectly, there is a problem in that the centrifugal force when the crane turns affects the moment of the crane, resulting in large measurement errors.

Furthermore, conventionally, as the load sensor is located at a high place, there is a problem in that it is difficult to attach and adjust the load sensor, which may be dangerous.

Furthermore, conventional moment limiters usually use not only a load sensor but also an angle sensor such as an inclinometer that detects the boom's elevation angle. Data such as the position of the center of gravity and the length of the boom are required, but in order to obtain this data, it is necessary to install additional sensors, and therefore it becomes necessary to improve or change the crane.

The present invention was made in view of the above-mentioned drawbacks of the conventional device, and is a crane system that detects various basic data that can be used to prevent overloads according to various operating conditions of the crane, using only a small number of load detection means of the same type. The present invention aims to provide a basic data detection device for overload detection.

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a truck crane to which the present invention is applied. In the figure, reference numeral 1 is a truck crane truck, and four outriggers 2a, 2b, 2c, and 2d, which are overhanging support legs for stably supporting the crane, are protruded from the sides of the truck 1. Load sensors 3a, 3b, 3c, and 3d, which are load detection means, are attached to the tip portions thereof. Specific examples of the load sensors 3a to 3d will be described in detail later, but strain gauges convert strain at a portion to which a load is applied into electrical signals to obtain load data. Reference numeral 4 denotes a turntable that is placed on the trolley 1 and rotates around the rotation center O. Reference numeral 5 denotes a boom whose one end is pivotally supported by the turntable 4 and whose other end lifts up a suspended load, and is configured to be able to be lifted up or down from the horizontal direction.

Next, regarding the load sensors 3a to 3d mentioned above,
This will be explained in more detail.

FIG. 2a shows the tip of the outrigger 2 on which the load sensor 3 is installed. A member called a float 6 is pivotally supported at the tip of the outrigger 2 by a support shaft 7, and is configured to fit the outrigger 2 on the ground.

FIG. 2b shows a cross section of this support shaft 7. Nuts 8, 8 are screwed onto both ends of the support shaft 7, and the float 6 is pivotally attached to the tip of the outrigger 2 by these nuts 8, 8. The support shaft 7 is hollow, and strain gauges 9, 9 serving as load sensors are attached to the inner surface thereof. Therefore, the load applied to one tip of the outrigger 2 is:
The support shaft 7 is distorted, and the strain can be detected by a strain gauge 9 having a Wheatstone bridge configuration, for example, and can be extracted as an electrical signal corresponding to the load.

FIG. 2c shows an embodiment in which the outrigger 2 is projected by a hydraulic cylinder 10 provided at the tip of the outrigger 2.

FIG. 2d is a cross-sectional view of the hydraulic cylinder 10, in which a pressure sensor (pressure transducer) 12 for detecting the internal pressure inside the cylinder is provided at the oil inlet and outlet of the cylinder chamber 11. sensor 1
The load applied to one of the outriggers 2 can be detected by the output of the outriggers 2.

FIG. 2e is a side view of the suspension system of the truck crane. In this embodiment, the load applied to the wheels 13 is detected by a load sensor installed in the suspension system.

In the figure e, reference numeral 14 is an axle that supports the wheel 13, and is fixed to a leaf spring 16 by a tightening bolt 15 and connected to a movable end of a suspension cylinder 17 serving as a damper. The upper end of this suspension cylinder 17 is connected to a truck frame 18. Both ends of the leaf spring 16 are connected to a truck frame 18. In this suspension system, in order to obtain an electrical output corresponding to the wheel load, for example, the inner wall or outer wall of the axle 14, as shown by A, generates shear strain, the upper surface of the axle 14, or the , the portion where bending strain is generated on the inner wall surface, and the pin that pivotally supports the leaf spring as shown by C are configured as shown in FIG. In addition, a compression type load converter may be inserted between the system to which the wheel load is transmitted.

Figures 3a and 3b are side views of a truck crane and diagrams showing moment balance in the figure for explaining the working radius calculation procedure according to the present invention, and Figures 4a and 4b are views of the boom from the center of rotation. FIG. 5 is a side view of a truck crane for explaining the procedure for calculating the distance to the center of gravity, and a diagram showing the balance of moments in the same figure. FIG. 5 is a schematic block circuit diagram showing the configuration of an embodiment of the present invention.

Below, the calculation procedure for various basic data under the operating conditions of the truck crane will be explained.

In Fig. 1, the x-axis and y-axis of the orthogonal coordinate system are taken as shown in the figure, and the distance between the load sensors 3a, 3c or 3b, 3d in the vertical direction is l, and the distance between the load sensors 3a, 3b or 3c, 3d in the horizontal direction is Let the distance between them be L.

(i) Detection of lifting load (weight) In Fig. 1, before the boom 5 lifts the load, that is, in a state where the lifting load is "0", the detected load values from each load sensor 3a to 3d (respectively P ₁ , P ₂ , P ₃ , P ₄ ) is adjusted to "0". After that, the suspended load is lifted by the boom 5, and as shown in FIG. 5, the load detection means 20a to 20d
For example, the detected load values from the load sensors 3a to 3d (corresponding to the load sensors 3a to 3d) are simply added together using the lifting load calculation means 21, which is an adder, as shown in W ₀ =P ₁ +P ₂ +P ₃ +P ₄ (1). The lifting load W ₀ can be obtained by

(ii) Detection of working radius Figure 3a is a side view of the crane of Figure 1, showing the x-plane. In this x plane, the horizontal distance from the turning center O to the suspended load 19 is set as Px (Similarly, in the y plane, the horizontal distance is set as Ry). In Figure 3b, P ₁₂ is x
It shows the sum of the detected load values P 1 and P 2 obtained from the load sensors 3a and 3b provided on the two outriggers 2a and 2b on one side of the direction (the left side in Fig. 1), and P ₃₄ is the sum of the detected load values P ₁ and P ₂ on the other side. The sum of the detected load values P ₃ and P ₄ obtained from the load sensors 3 c and 3 d provided on the two outriggers 2 c and 2 d on one side (the right side in Fig. 1) is shown (P ₁₃ , which will be described later).
(Same as P ₂₄ ). Considering the moment balance, P ₁₂・l=Wo(Rx−l/2) (2), and rewriting this equation, Rx=(P ₁₂・l)/Wo+l/2 (2)′ The horizontal distance in the x direction is found. Similarly, the horizontal distance Ry in the y direction is Ry = (P ₂₄ · L) / Wo + L / 2 (3) Therefore, the actual working radius R is calculated from equations (2)' and (3) as follows: R = (Rx ² + Ry ² ) ^1/2 (4). If we look _at this in _FIG .
1 to the lifting load Wo, and the support point spacing data L, l in the x direction and y direction (i.e., the lateral outrigger spacing L,
The working radius calculation means 23 receives the longitudinal outrigger spacing l) as an input signal, and calculates the above-mentioned
Equations (2)', (3), and (4) are calculated to obtain the horizontal distance of the boom, that is, the working radius R.

(iii) Detection of the horizontal distance from the rotation center O to the center of gravity of the boom 5 As shown in Figure 4a, the length of the boom 5 is H, the center of gravity of the boom 5 is the center of rotation of the boom 5 (the rotation axis of the boom 5) ) is the length up to H _B , the weight of boom 5 is W _B , and the weight of turntable 4 is Wc
(Lifting load Wo applied to load sensors 3a to 3d
and the weight of the crane other than the weight of the boom 5 W _B ), and the center of rotation O as shown in Figure 4b.
Let x be the distance to the load point of the weight Wc of the turntable 4, and R _BX be the horizontal distance between the rotation center O and the load point of the weight _WB of the boom 5. From the balance of moments, Wc (x + l/2) =W _B (R _{BX −l} /2 ₎ +Wo( _R
[Wc (l/2 + x) - Wo (Rx - l/2) / W _B + l/ 2] (5)' Therefore, the horizontal distance R _B to the center of gravity of the actual boom 5 is obtained by finding the working radius R. Similarly to the case where R _By is the distance in the y plane, R _B = (R _BX ² + R _By ² ) ^1/2 (6) can be obtained.

To explain this with reference to the block diagram of FIG. 5, the working radius calculation means 23 calculates the working radius Rx,
Ry is calculated from the lifting load calculation means 21 by the lifting load Wo.
, support point spacing data L, l from the support point spacing data generator 22, turntable dead weight Wc (truck crane dead weight excluding boom dead weight and hanging load) and boom dead weight
The boom center of gravity distance calculation means 25 receives W _B as an input signal, and performs the above calculation to calculate the horizontal distance R _B from the center of rotation to the center of gravity of the boom 5.
can be found.

(iv) Detection of boom length The length H of the boom 5 is determined by the angle of depression and elevation of the boom 5 as shown in Fig. 4a, and the length H of the boom 5 from the turning center O.
horizontal distance to the foot pin (lower edge of the boom).
If it is l', it can be found using the distance R _B to the center of gravity of the boom 5 found in (iii).

R−l′=H・cosθ (7) R _B −l′=H _B・cosθ (7)′ From equations (7) and (7)′, H=H _B・(R−l ′)/(R _B −l′) (8) Here, assuming that the boom 5 is a telescopic boom that can be extended and contracted, H _B is a function of H, that is, H _B =
Expressing it in terms of f(H), the length H of the boom can be found as H=f(H)·R/R _B (8)'.
To explain this with reference to FIG. 5, the working radius R is calculated from the working radius calculating means 23, and the boom center of gravity
R _B and preset function f(H) data from the boom length function f(H) setter 26 are received as input signals, respectively, and the boom length H is calculated by the boom length calculation means 27.

(v) Detection of elevation angle From equation (7) in (iv), it can be determined as θ=arccos {(R−l′)/H} (9). This data can be obtained by calculation by the elevation angle calculating means 28 in FIG. It can also be obtained from equation (7)' as θ=arcos {(R _B −l')/H _B } (9)'.

(vi) Detection of boom turning angle Turning angle of boom 5 from the x-axis (see Figure 1)
If we take φ, then using the cosine theorem from the x-direction component Rx and y-direction component Ry obtained from the working radius R in (ii), Ry ² = R ² + Rx ² −2R・Rx・cosφ (10) This formula Solving (10) for φ, φ=arccos {(R ² + Rx ² − Ry ² )/2R・Rx}
(10)′ can be obtained.

This calculation is performed by the turning angle calculation means 2 in FIG.
9.

As mentioned above, FIG.
Load sensors 3a to 3d (or load detection means 20a to 20
Using the detected load values P ₁ to _{P 4} in d), perform the steps (i) to (vi) above.
3 is a flowchart showing the steps of detecting or calculating various basic data described in . This flowchart is redundant as described above, so the explanation thereof will be omitted.

According to the above-described embodiment, only the load detection values P ₁ to _{P 4} of the four load sensors provided on the outrigger or the wheel support are detected, and the overload sensor used in crane safety devices such as moment limiters can be used. All data for load detection can be obtained by simple calculations (means). In particular, since the detector does not use different types of detectors as in the past, it is possible to achieve high accuracy, and it is possible to install, adjust, inspect,
Maintenance is easy and total cost can be reduced.

In addition, as shown in Fig. 2 a to e, the load sensors 3a to 3d are installed on the outrigger 2 or the axle 14 of the truck in any case, so the load sensors 3a to 3d are attached/detached and adjusted. It is extremely easy to do so, and there is no danger associated with installing it at a high place. In addition, as in the past, a load sensor 3a is installed on the moving part of the boom 5, etc.
When ~3d was installed, there were cases where the detected value changed due to centrifugal force, but if it is installed in a place that does not move during work like this, there is no such worry and accurate detection is possible. .

Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

For example, in the above embodiment, the load sensor is of the type inserted between the tips of the outriggers 2a to 2d and the float, but the point is that each outrigger undergoes elastic deformation in response to the load applied to it. All you have to do is attach a strain gauge to that part.

In addition, the number of load sensors only needs to be installed as many as the number of outriggers or wheels that are grounded on the fixed ground. For example, if the outriggers are supported at three points, the above basic data can be obtained with three load sensors. be able to.

As described in detail above, according to the present invention, a crane can be operated by using only a very small number of load detection means of the same type and installed on each overhanging support leg or each axle or member supporting the axle of the crane. It is possible to detect basic data essential for overload detection, such as the lifting load, working radius, boom length, boom elevation angle, and boom rotation angle under operating conditions. This can be achieved using simple and inexpensive configurations of calculation means, and the load detection means is easy to install, adjust, maintain, etc. on the crane, and the total cost associated with overload detection is significantly reduced compared to conventional methods. It is possible to provide a basic data detection device for detecting overload of a crane.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a truck crane to which the present invention is applied, FIGS. 2 a to e are diagrams showing examples of installation of various types of load detection means according to the present invention, and FIGS. 3 a and b
4 is a side view of a truck crane and a diagram showing the balance of moments in the same figure to explain the procedure for calculating the working radius in the device of the present invention, and Figures 4a and 4b are diagrams showing the calculation of the horizontal distance from the center of rotation to the center of gravity of the boom A side view of a truck crane and a diagram showing the moment balance in the same figure for explaining the procedure, FIG. 5 is a circuit block diagram showing the configuration of an embodiment of the present invention, and FIG. 6 shows the operation of the same embodiment. A flowchart is shown to explain. DESCRIPTION OF SYMBOLS 1... Trolley, 2a-2d... Outrigger, 3... Load sensor, 4... Turntable, 5... Boom, 6...
Float, 9... Strain gauge, 12... Pressure sensor, 14... Axle, 19... Hanging load, 20... Load detection means, 21... Lifting load calculation means, 22... Support point interval data generator, 23... Working radius calculation means , 24
...Turntable and boom dead weight data generator, 25...Boom center of gravity distance calculation means, 26...Boom length function f(H) setting device, 27...Boom length calculation means, 28...Elevation angle calculation means, 29...Turning angle calculation means.

Claims (1)

[Scope of Claims] 1. Detection of overload caused by the dead weight of a boom and the lifting load lifted by the boom in a truck crane that lifts a load by projecting a plurality of overhanging support legs above a fixed ground. A device for detecting basic data for carrying out the above-mentioned boom includes load detecting means installed on each of the overhanging support legs and independently detecting the load applied to the overhanging support legs; Lifting load calculation means calculates the lifting load by adding each load detected by the load detection means when an arbitrary lifting load is applied with reference to when no lifting load is applied; Based on each detected load, the lifting load from the lifting load calculation means, and each known horizontal distance in the x direction and y direction of the overhanging support leg, a working radius calculating means for calculating a working radius from the balance of each moment with the two overhanging support legs on one side as fulcrums; a boom center of gravity distance calculation means for calculating a horizontal distance from the rotation center of the crane to the center of gravity of the boom based on the balance of the moment due to its own weight; boom length calculation means for calculating the length of the boom from the distance from the center of rotation of the boom to the center of gravity of the boom, which is a function of the length of the boom; and the working radius and the length of the boom or the center of rotation. an elevation angle calculation means for calculating an elevation angle of the boom from the horizontal distance from the center of gravity of the boom to the center of gravity of the boom, the distance from the center of rotation of the boom to the center of gravity of the boom, and the distance from the center of rotation to the center of rotation of the boom; the x direction and y of the working radius
1. A basic data detection device for detecting overload of a crane, comprising: a turning angle calculating means for calculating a turning angle of a boom from a reference angular position using the cosine theorem from each component of the direction. 2 Basic data for detecting overload caused by the dead weight of the boom of a truck crane, which is supported on the fixed ground via the wheels of the truck and used to lift loads, and the lifting load lifted by the boom. The detecting device includes a load detecting means installed on each axle or a member supporting the axle to independently detect the wheel load of each wheel, and a load detecting means installed on each axle or a member supporting the axle, and a load detecting means installed on each axle or a member supporting the axle, and with reference to when no lifting load is applied to the boom. Lifting load calculating means for calculating the lifting load by adding each load detected by the load detection means when an arbitrary lifting load is applied; and each wheel load, the lifting load, and the wheel. Working radius calculation means for calculating a working radius from the balance of each moment with two wheels on each side in the x direction and y direction among the wheels as fulcrums based on horizontal distances in the x direction and y direction. and a boom center of gravity, which calculates the horizontal distance from the crane's rotation center to the boom's center of gravity based on the balance of moments caused by the known dead weight of the boom, the dead weight of the truck crane other than the boom, the lifting load, and the working radius. a distance calculating means, a distance from the center of rotation of the boom to the center of gravity of the boom, which is a function of the working radius, the distance from the center of rotation to the center of gravity of the boom, and a preset length of the boom; boom length calculating means for calculating the length; and the working radius and the length of the boom, or the horizontal distance from the rotation center to the center of gravity of the boom, the distance from the center of rotation of the boom to the center of gravity of the boom, and the An elevation angle calculation to obtain the elevation angle of the boom from the distance from the turning center to the rotation center of the boom, and the x of the working radius.
1. A basic data detection device for detecting overload of a crane, comprising a turning angle calculation means for calculating a turning angle of a boom from a reference angular position using the cosine theorem from each component in the direction and the y direction.