JPH0422839B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is an overload control system used in construction machines, such as cranes and aerial work vehicles, whose load limit values vary in stages depending on the horizontal rotation area of the boom. This invention relates to a load protection device.

(Prior Art) Conventionally, overload prevention devices used in this type of construction machinery have been designed to prevent the horizontal movement of the boom. The allowable load limits for the boom corresponding to the swing areas (for example, forward swing area, right side swing area, rear swing area, and left side swing area) are memorized, and from among these load limit values, the boom is actually Read the load limit value corresponding to the horizontal swing area where the When the ratio is reached, a rotation stop signal for stopping the horizontal rotation of the boom is output, and this signal is used to stop the horizontal rotation of the boom.

After the horizontal rotational movement has stopped in this manner, the operation to return to the safe side can be performed manually by the operator by determining the direction of the return rotational movement to the safe side, or the As disclosed in the publication, the direction of the return rotation movement to the safe side is determined by hard logic using a combination of a rotation area detection switch that detects the rotation area in which the boom is located and a rotation direction detection switch that detects the rotation drive direction. What was used was a device that was uniquely set and automatically performed based on this signal.

(Problems to be Solved by the Invention) However, in the former method, there is a risk that the operator's incorrect operation may cause the construction machine to turn to an unsafe side and cause the construction machine to fall; In a construction machine equipped with an outrigger device, the load limit value varies depending on the extension width of the outrigger device. For example, if the outrigger device is extended by a certain extension width, the load limit value in the front or rear turning area is higher than the load limit value in the right or left side turning area. However, when the outrigger device is extended further, the stability of the construction machine on the right or left side increases, and the load limit value in the right or left side turning area is higher than the load limit value in the forward or backward turning area. Takes a value. Therefore, the magnitude relationship of the load limit values in both adjacent swing areas is reversed, but in such a case, the direction of the return swing movement must be uniquely determined according to the boom horizontal swing position (swivel area). Since it cannot be configured, there was a problem that hardware logic could not be assembled by combining switches.

The present invention has been made in view of the above problems, and is such that the direction of the return movement to the safe side after the horizontal turning movement is stopped by the turning stop signal is reversed depending on the extension width of the outrigger device. An object of the present invention is to provide an overload prevention device for a construction machine that enables only the return rotation movement to the safe side even if the construction machine is a heavy-duty construction machine.

(Means for Solving the Problems) In order to achieve the above object, the overload prevention device for construction machinery of the present invention is configured as follows. In other words, when the current value of the load acting on the boom reaches a predetermined ratio with respect to the load limit value that varies depending on the horizontal rotation area of the boom, a rotation stop signal is output to stop the horizontal rotation movement of the boom. In the overload prevention device of construction machinery, when the overload prevention device outputs a rotation stop signal in response to the horizontal rotation movement of the boom and the horizontal rotation movement has stopped, the rotation area where the boom is currently located. A swing operation detector is provided to memorize the swing area in which the boom was located before entering the area and to detect the operating direction of the swing operation lever after the horizontal swing is stopped. When it is determined that the operating direction of the swing operation lever is being operated to horizontally swing from the swing area where the boom is currently located toward the memorized swing area based on the information from the swing area and the swing operation detector. The rotation stop signal is configured to stop outputting the rotation stop signal, and continue outputting the rotation stop signal at other times.

(Function) The overload prevention device for construction machinery according to the present invention has the following features:
When the overload prevention device outputs a rotation stop signal due to the horizontal rotation movement of the boom, the rotation area where the boom was located before entering the stop rotation area where the horizontal rotation movement stopped is memorized. The operating direction of the swing operating lever is determined from the swing area related to this memory, the swing area where the boom is currently located, and the operating direction of the swing operating lever operated by the operator. Determine whether or not the boom is to be horizontally swung toward the memorized swiveling area, and operate the operating lever so that the operating direction of the control lever is to horizontally swivel from the swiveling area where the boom is currently located toward the memorized swiveling area. Since the output of the swing stop signal is stopped when it is determined that the rotation stop signal is Only the return movement to the side can be performed automatically without relying on the operator's judgment.

(Examples) The present invention will be described below based on Examples. FIG. 1 is a conceptual diagram for explaining the configuration of the present invention,
CA is the body of the crane vehicle, aerial work vehicle, etc., OR is the outrigger device, and 0 is the turning center of the boom BM. In addition, A, B, C, and D indicate the respective turning areas surrounded by line segments connecting the grounding points of each outrigger device OR with the turning center 0 as the center, and represent the forward turning area A and the right turning area, respectively. B, rear turning area C,
This is the left turning area D. In addition, in this type of construction machine, the load limit value in each swing area varies depending on the extension width of the outrigger device, but in this example, the load limit value in the forward swing area A and the rear swing area C is An example will be described in which the load limit value is set high, and the load limit value in the right side turning area B and the left side turning area D is set low, and the load limit value is configured to vary in stages depending on the horizontal turning position of the boom BM. shall be taken as a thing.

FIG. 2 is a block diagram of an overload prevention device constituting an embodiment of the present invention, which schematically shows a group of detectors for detecting the operating state of the construction machine;
Based on the input information from the detector group, the operating state of the construction machine is monitored based on the built-in calculation program and stored information, and if necessary, an alarm signal is issued and the present invention returns to the safe side after the rotation has stopped. It consists of an information processing device that controls the movement of the vehicle, and an alarm device that issues an alarm based on the alarm signal.

First, the detector group will be explained. Reference numerals 1 and 2 are a boom angle detector and a boom length detector for detecting the current operating state of the boom BM, both of which are constructed of known detectors using potentiometers. The output values of these detectors 1 and 2 are amplified by amplifiers 7 and 8, respectively, and then sent to the A/D converter 1.
2, the signal is converted into a digital value and output to the gate 13. 3 is boom
This is a moment detector that detects the current value of the load acting on the BM, and consists of a strain gauge attached to the rod of the boom hoisting cylinder. The output value of the moment detector 3 is amplified by amplifiers 9 and 10, and then sent to an A/D converter 12.
The signal is converted into a digital value and output to the gate 13. 4 is boom BM
This is a turning operation detector that detects right turning operation and left turning operation of This detection signal is output to the gate 14. 5 is boom
This is a turning position detector that detects the turning position of the BM, and as shown in FIG.
Cam 5 having convex portions corresponding to area angles C and D
a, 5b, 5c, 5d, and the cams 5a, 5b, 5c, which rotate in conjunction with the horizontal rotation of the boom BM.
It is composed of four limit switches 5a', 5b', 5c', and 5d arranged so as to face the convex part 5d, and detects the turning area in which the boom BM is currently located, and detects the turning area where the boom BM is currently located. A turning area signal corresponding to the rotation area signal is output toward the gate 15.

C is an information processing device, which is composed of a known microcomputer. The information processing device C
is the load limit value for each turning area [load limit value in forward turning area A (LM-A), load limit value in right turning area B (LM-B), load in rear turning area C Data ROM 19 that stores the limit value (LM-C) and the load limit value (LM-D) in the left side turning area D, monitoring the operating status of the construction machine and returning to the safe side after stopping the turn. A program ROM 18 stores arithmetic programs for controlling motion, etc., a RAM 17 temporarily stores information from each detector while continuously updating it, and the operating state of the construction machine is determined according to the arithmetic program stored in the program ROM 18. It is composed of a CPU 16 that performs arithmetic processing such as monitoring and controlling the rotation movement to return to the safe side after stopping the rotation, and an address decoder 20 that issues opening/closing commands to gates etc. for the transmission and reception of input signals and output signals. ing.

Address decoder 20 cyclically includes gates 13,
14 and 15 to control the opening and closing, and the information from each detector (boom length l, boom angle θ, current load value M, swing operation signal, swing area signal) is read in from each gate and continuously stored in RAM 17. It is designed to be updated and memorized.

In addition, the rotation area signal detected by the rotation position detector 5 includes the rotation area signal corresponding to the rotation area where the boom BM is currently located, as well as the rotation area signal corresponding to the rotation area where the boom BM is currently located. Boom BM
A turning area signal corresponding to the turning area where the vehicle was located is also stored in the RAM 17.

The CPU 16 reads the load limit value of the construction machine in the current operating state from the data ROM 19 based on the detection information detected by the boom angle detector 1, the boom length detector 2, and the rotation position detector 5, respectively.
An alarm that compares the load limit value with the current load value detected by the moment detector 3, and activates an alarm to be described later when the current load value reaches a predetermined ratio such as 90% or 100% of the load limit value. It is designed to output a signal. In addition, if the boom BM turns from a swing area with a high load limit value to a swing area with a low load limit value at the same time as the alarm signal, resulting in an overload condition, the boom may rotate horizontally even further. In order to prevent construction machinery from becoming even more dangerous, a rotation stop signal that stops horizontal rotation is now being output.
The control procedure for returning to the safe side after the rotation is stopped by the rotation stop signal will be described in detail later.

The alarm includes a solenoid valve 28 that is installed in the boom drive hydraulic circuit and automatically stops related operations of the boom BM, and a horn 27 and an indicator light 24 that notify the operating status of the construction machine. They are activated when an alarm signal is output from the address decoder 20 to the corresponding latch drivers 23 and 26, respectively, to automatically stop boom-related operations and to notify the operator with an alarm or the like. Note that 22 is a numerical display for numerically displaying the operating status and load status of the construction machine.

The overload prevention device outputs a swing stop signal and the control of the return swing movement to the safe side after the horizontal swing movement is stopped will be described in detail below.

If the construction machine turns from a swing area with a high load limit value to a swing area with a low load limit value due to the horizontal swing movement of the boom BM, and the load limit value suddenly drops and an overload condition occurs, an overload occurs. The prevention device outputs a rotation stop signal together with an alarm signal to stop the horizontal rotation movement.

In this state, the CPU 16 first detects the rotation area signal detected by the rotation position detector 5 and continuously stored in the RAM 17, that is, the position of the boom before entering the rotation area where the boom BM is currently located. The rotation area signal corresponding to the rotation area where the boom BM is currently located and the rotation area signal corresponding to the rotation area where the boom BM is currently located are read out. Next, the turning operation detector 4 detects whether the direction in which the turning operation lever is operated again after the turning is stopped, that is, the direction of the restarted turning movement is the right turning direction or the left turning direction. The detection result is taken in through the gate 14.

Then, according to the calculation program, a signal corresponding to the re-operation direction of the swing operation lever and a swing area corresponding to the swing area where the boom was located before entering the swing area where the boom BM is currently located read out. The signal and the rotation area signal corresponding to the rotation area where the boom BM is currently located are compared, and the operation direction of the rotation operation lever is determined to move the boom BM from the rotation area where the boom is currently located to the direction of the rotation area related to the memory, i.e. It is determined whether or not the boom BM is to be horizontally turned in the direction of the turning area where the boom BM was located before entering the turning area where the boom BM is currently located. As a result, when it is determined that the operating direction of the swing control lever is being operated so as to horizontally swing from the swing area where the boom BM is currently located toward the memorized swing area, the output of the swing stop signal is stopped. At other times, the output of the turning stop signal is continued.

Next, its effect will be explained.

In the following explanation, the current boom operating state, that is, the current boom angle θ and boom length l, will be used with a load suspended on the boom BM.
While maintaining , move the boom BM to the forward rotation area
A case in which the vehicle is horizontally pivoted from a turning region with a high load limit value to a rightward turning region B (a turning region with a low load limit value) will be described as a representative example.

In forward turning area A, the current load value was lower than the load limit value (LM-A) for this turning area, and boom-related operations were possible, but as soon as the right side turning area B was entered, this turning Assume that the load limit value (LM-B) in the area is exceeded, a rotation stop signal is output together with an alarm signal, and the horizontal rotation movement is stopped.

The CPU 16 uses the rotation position detector 4 to detect the rotation area that constantly changes due to the horizontal rotation movement of the boom BM, and corresponds to the rotation area where the boom BM is currently located (in this case, the right side rotation area B). Continuously transmits the rotation area signal that corresponds to the rotation area signal in which the boom was located, and the rotation area signal corresponding to the rotation area where the boom was located before entering the rotation area where the boom BM is currently located (in this case, the forward rotation area A). It is stored in RAM17. Therefore, when the rotation stop signal is output, the CPU 16 first selects from among the memory values stored in this RAM 17 the rotation area where the boom BM is currently located (right side rotation area B) and the current position of the boom BM. The value stored in the RAM 17 corresponding to the swing area (front swing area A) where the boom was located before entering the current swing area is read out.

In this state, the operator should press the boom again.
When the turning operation lever is operated to turn the BM to the right (clockwise), this operation is detected by the turning operation detector 4, and the detection result is temporarily stored in the RAM 1.
Incorporated into 7.

Next, the CPU 16 generates a signal corresponding to the operating direction of the swing operation lever temporarily stored in the RAM 17, a signal read from the RAM 17 and corresponding to the swing area where the boom BM is currently located (right side swing area B), and the signal corresponding to the swing area where the boom was located before entering the swing area where the boom BM is currently located (forward swing area A), and the direction in which the operator operates the swing control lever is determined. It is determined whether the boom BM is to be horizontally rotated from the current rotation area to the memorized rotation area. In this case, the operator is performing a right turning operation, and this right turning operation moves the boom BM from the turning area where the boom is currently located (right side turning area B) to the memorized turning area (forward turning area A). ), the output of the rotation stop signal continues. This restricts the horizontal rotation of the boom BM toward the dangerous side, making it possible to prevent the operating state of the construction machine from becoming even more dangerous.

On the other hand, when the operator operates the swing control lever to turn the boom BM to the left, the left turn operation of the swing control lever operated by the operator
Since this is a turning operation to horizontally turn the boom BM from the turning area where the boom is currently located (right side turning area B) towards the turning area related to the memory (forward turning area A), the CPU 16 uses this judgment result. The output of the rotation stop signal is stopped based on this. As a result, the address decoder 20 controls the latch driver 26 to deenergize the solenoid valve 28, so that the boom returns to the safe side toward the swing area where it was located before entering the stop swing area. This allows rotational movement.

In the above explanation, the case where the boom BM is horizontally rotated from the forward rotation area A to the right side rotation area B direction is explained, but from the front rotation area A to the left side rotation area D direction, or from the rear rotation area C to the right side rotation area Even if the horizontal turning movement is made to the left turning area B and the left turning area D, the same function is achieved.

Note that the boom moves from the right side turning area B and the left side turning area D, where the load limit value is low, to the forward turning area A, and the rear turning area C, where the load limit value is high.
When the BM is rotated horizontally, the load limit value after entering the area due to the horizontal rotation movement is higher than the load limit value before entering the area, so the construction machine becomes overloaded and a rotation stop signal is output. There is no need to control the rotation movement to return to the safe side after the rotation has stopped.

In addition, the above-described embodiment was applied to a construction machine in which the extension width of the outrigger device does not change and the magnitude relationship of the load limit values of both adjacent turning areas does not reverse. It goes without saying that the same method can be applied to a construction machine in which the extension width varies and the magnitude relationship between the load limit values of both adjacent turning regions is reversed.

(Effects of the Invention) The overload prevention device of the construction machine of the present invention can prevent the overload prevention device from moving to the safe side after stopping the horizontal swing, even if the construction machine is such that the magnitude relationship of the load limit values in both adjacent swing areas is reversed. Only the return rotation movement can be performed automatically without relying on the operator's judgment, and it has excellent effects.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing each swing area of a construction machine in which the load limit value varies stepwise depending on the horizontal swing area of the boom BM, and Fig. 2 is a block diagram showing the overload prevention device for the construction machine of the present invention. The diagram, FIG. 3, is an explanatory diagram of the configuration of a swing position detection device used in the overload prevention device for construction machinery of the present invention. BM: Boom, A: Forward turning area [area with high load limit value], C: Back turning area [area with high load limit value], B: Right side turning area [area with low load limit value], D: Left side Directional turning area [area with low load limit value], 4: Turning operation detector, 5: Turning position detector.

Claims (1)

[Scope of Claims] 1. Swing stop for stopping the horizontal swing movement of the boom when the current value of the load acting on the boom reaches a predetermined ratio with respect to the load limit value that varies depending on the horizontal swing area of the boom. In an overload prevention device for construction machinery that outputs a signal, the overload prevention device outputs a rotation stop signal in response to horizontal rotation of the boom, and when the horizontal rotation has stopped, the current position of the boom is A swing operation detector is provided that stores the swing area in which the boom was located before entering the swing area where the boom is located, and detects the operating direction of the swing operation lever after the horizontal swing is stopped. Based on the rotation area where the boom is currently located and the information from the rotation operation detector, the operation direction of the rotation operation lever is operated to horizontally rotate from the rotation area where the boom is currently located toward the memorized rotation area. An overload prevention device for a construction machine, characterized in that the overload prevention device for a construction machine is configured to stop outputting the swing stop signal when it is determined that the swing stop signal is present, and to continue outputting the swing stop signal at other times.