JPH0262475B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an overload prevention device used in construction machines such as cranes, aerial work vehicles, etc., in which the load limit value changes stepwise depending on the horizontal rotation position of the boom, and in particular, the present invention relates to an overload prevention device used in construction machines such as cranes, aerial work vehicles, etc. The present invention relates to a load prevention device that can reliably control the stop of a swing operation when the load reaches a limit due to a swing movement in a region. The working capacity of a construction machine with a boom is determined by its mechanical strength and stability, so the operating state of the boom (the boom's up-and-down state and extension/contraction state)
It also varies depending on the turning state of other booms. In general, this type of construction machinery does not have the same stability over the entire swing range of the boom, but rather an area with high stability, that is, an area with a high load limit value and an area with low stability adjacent to this. In other words, it has a region with a low load limit value. This means that if a load is lifted in an area with a high load limit and then swiveled in the direction of an area with a low load limit, the allowable load on the boom (limit value) decreases,
This indicates that the actual load exceeds the limit value and there is a risk of falling. For this reason, with this type of construction machinery, in order to prevent work from exceeding the load limit value, which fluctuates depending on the operating state of the boom (boom's up/down state and extension/retraction state) as well as the boom's rotation state, The load limit value specified based on the state and swing state is memorized for each swing region of the boom, and the limit value corresponding to the swing region where the boom is actually located is read out based on the boom swing direction. An overload prevention device is provided, which is configured to compare the value with the current value of the load acting on the boom and generate a warning signal or a stop signal to stop the relevant operation of the boom when the latter value reaches the former value. It was getting worse. However, such conventional overload prevention devices read the load limit value corresponding to the swing area where the boom is actually located based on the swing direction of the boom. When the boom is rotated to a lower swing area from a low load limit value, the load limit value of the swing area entered is read for the first time when the boom enters a swing area with a low load limit value, and the result of comparing this load limit value with the current load value. Based on this, an alarm signal or a stop signal is output to stop the swinging motion of the boom, so in construction machinery with a large inertial mass, the swinging motion is caused by inertia, and the swinging motion actually stops only when the load limit value is low. There was a problem in that the overload prevention device was unable to achieve its intended purpose of preventing an overload condition because the overload prevention device entered the state deeply into the area. The present invention has been made to solve the above problems, and when the boom swings from a swinging area with a high load limit value to a swinging area with a low load limit value, before entering the swinging area with a low load limit value. An overload prevention device for construction machinery that determines whether work can be continued safely in the turning area with a low load limit that will be entered next, and controls the stopping of the turning movement based on the judgment result. The purpose is to provide the following. The overload prevention device for construction machinery of the present invention is configured as follows in order to achieve the above-mentioned object. In other words, in addition to the functions of conventional overload prevention devices,
A boundary area is established between the swing area with a high load limit value and the swing area with a low load limit value, and when the swing movement of the boom enters the boundary area from the swing area with a high load limit value, the swing area with a low load limit value is set at the time of entering the boundary area. The load limit value of the area is compared with the current load value, and when the latter value has a predetermined relationship with the former value, it is configured to issue a turning warning signal with a different warning method and warning pattern from conventional warning signals. This is what I did. In addition, in the second invention, a boundary area is provided between a swing area with a high load limit value and a swing area with a low load limit value, and when the swing movement of the boom enters the boundary area from the swing area with a high load limit value, the boundary area is A slow stop signal that compares the load limit value in the swing region where the load limit value is low at the time with the current load value, and gently stops the swing movement of the boom when the latter value has a predetermined relationship with the former value. It is designed to emit. As a result, when the boom is rotated from a swing area with a high load limit value to a swing area with a low load limit value, the moment the boom enters the boundary area between the swing area with a high load limit value and the swing area with a low load limit value. In other words, while the boom is located in a swing area with a high load limit value, the load limit value in the swing area with a low load limit value is read out and the load limit value in the swing area with a low load limit value is read out, and the load limit value and the current load value are read out. Before the boom actually enters the swing area where the load limit value is low, it is possible to determine whether work can be continued safely in the swing area where the load limit value is low. If it is determined that it is necessary to stop the swinging movement of the boom due to an overload when turning into a swinging area with a low load limit value, the boom should be rotated with sufficient margin before entering the swinging area with a low load limit value. can be stopped. In addition, in the first invention, the load limit value in the turning region where the load limit value is low is compared with the current load value, and based on the comparison result, a turning warning signal is outputted as a turning warning signal with a different warning method and warning pattern from the conventional warning signal. Since the slewing warning signal is configured to be configured to Appropriate danger avoidance operations (operation to stop boom rotation) can be performed without having to do so. In addition, in the second invention, the load limit value in the swing region where the load limit value is low is compared with the current load value, and the comparison result is configured to output a slow stop signal to gradually stop the swing operation of the boom. Therefore, in response to this slow stop signal, the swinging movement of the boom can be stopped slowly, thereby reducing the shock when stopping the swinging. The present invention will be explained below based on examples. Figure 1 is a conceptual diagram for explaining the configuration of the present invention.
is the body of the crane vehicle or aerial work vehicle, OR is the outrigger device, and O is the center of rotation of the boom BM. In addition, A, B, C, and D indicate each turning area surrounded by a line segment connecting the grounding points of each outrigger device OR with the turning center O as the center, and respectively indicate the forward turning area A and the right turning area. These are area B, rear turning area C, and left turning area D. In this embodiment, based on design specifications, the load limit values for the forward turning area A and the rear turning area C are set high, and the load limit values for the left and right side turning areas B and D are set low. a, b, c, and d are boundary areas provided at both ends of the front area A and the rear turning area C, that is, at the boundaries of each turning area A, B, C, and D, and the angles are such that turning at the rated speed is possible. The angle is set at a somewhat greater angle than is necessary to safely stop the boom. FIG. 2 is a block diagram of an overload prevention device constituting an embodiment of the present invention. The moment detector 1 detects the current value of the load acting on the boom BM, and is composed of a conventionally well-known load cell, etc., and the detected value is sent to the information processing device 2, which will be described later.
3, it is calculated and compared with the load limit value. Note that since this detected value is an analog value, it is amplified by an amplifier 6, converted to a digital value by an A/D converter 10, and temporarily stored in a RAM 20 via a CPU 19. The boom length detector 2 detects the amount of expansion and contraction of the boom BM, the heave angle detector 3 detects the heave angle of the boom BP, and the working state detector 4 detects the extended state of the outrigger device OR and the installation state of the jib. Data on the load limit value for each current working condition
It is used to obtain an index signal for reading from the ROM 22, and is comprised of conventionally known potentiometers, limit switches, and the like.
Since the detection values of the boom length detector 2 and the heave angle detector 3 are analog values, they are amplified by amplifiers 7 and 8, then converted to digital values by the A/D converter 10, and then sent to the CPU.
19, and is temporarily stored in the RAM 20. Further, the detection signal of the working state detector 4 is also temporarily stored in the RAM 20 via the CPU 19. The CPU 19 reads data from the boom length detector 2, luffing angle detector 3, and working state detector 4 stored in the RAM 20 as index signals.
The load limit value corresponding to the current operating state of the boom is read from the ROM 22, and this value is compared with the latest current load value stored in the RAM 20, so that the latter value has a predetermined relationship with the former value. In other words, when the current load value is 90% of the load limit value
Alternatively, when it reaches 100%, a warning signal or a stop signal to stop related operations of the boom, which will be described later, is output. The rotation position detector 5 detects the rotation position of the boom BM and outputs this detected value to be stored in the RAM 20. The RAM 20 continuously records the current rotation position information and the immediately preceding adjacent rotation position information. It is designed to be memorized while being updated. In this embodiment, the turning position detector 5 is composed of three cams and a limit switch, and the truth values corresponding to each turning area and boundary area are determined as shown in the table below.

[Table] Based on the above truth table, cams x, y, and z are formed as shown in FIG. The cam x adjusts the formation area of the convex periphery to the area angle that is the sum of the forward turning area A, the boundary area a, the right side turning area B, and the boundary area b, and the cam y adjusts the forming area of the convex periphery to the boundary area a, the boundary area a, The cam z is adjusted to the combined area angle of the forward rotation area A, the boundary area d, and the left side rotation area D.
The formation area of the convex periphery is provided in two places: the area angle that combines the forward rotation area A and the boundary area d, and the area angle that combines the rear rotation area C and the boundary area b, and these three cams x, y , z are attached coaxially and overlappingly, and are designed to rotate in conjunction with the boom BM. A limit switch is attached to the convex periphery of each cam x, y, and z.
When it comes into contact with the convex portion, an ON signal is output and, as described above, is taken into the RAM 20. The CPU 16 is adapted to determine the swing area of the boom BM based on the combination of signals (that is, the combination of truth tables) thus captured. The information processing device is the aforementioned CPU19 and RAM2.
0, program ROM21 and data
It has a built-in ROM 22, and the data ROM 22 stores a series of load limit values using parameters such as the boom length, the heave angle, the extended state of the outrigger device, and the device state of the jib. Note that, as described above, this load limit value has a high value and a low value that differ depending on the turning region. The program ROM 21 stores a program for comparison calculation processing performed by the CPU 19, and the CPU 19 reads out the load limit value, compares the load limit value with the current load value, and sends an alarm signal or boom-related operation stop signal in accordance with this program command. It is designed to perform processing such as output. The interface 15 receives the above-mentioned output signals (alarm signal and stop signal) and supplies power to the solenoid valve for stopping the alarm or boom-related operation, and unloads the hydraulic oil for driving the alarm or the boom. There is. The display 17 displays the load value, load rate, etc. acting on the boom. Next, in the overload prevention device of the present invention having such a configuration, a method for controlling the stop of the boom rotation according to the program stored in the program ROM 21 will be described. The overload prevention device of the present invention is different from conventional devices in that it functions to issue a warning signal or a stop signal to stop related operations of the boom when an overload occurs due to boom BM extension, collapse, or lifting of a load. This is similar to the overload prevention device. A new function added to the functions of conventional overload prevention devices is control to stop the swing movement when the boom swings from a swing range with a high load limit value to a swing range with a low load limit value. An example of a case in which the boom is pivoted from a forward swing area A where the load limit value is high to a right side swing area B where the load limit value is low will be described with reference to FIG. In the forward swing area A, load is placed on the boom BM (load lighter than the load allowed in the forward swing area).
Suppose that the vehicle was suspended and was pivoting in the direction of rightward pivot area B. (Middle point in the figure). It enters the boundary area a before the right side turning area B (point in the figure), but at the time of entering the area, the information processing device 23 detects the turning position detector 5.
It recognizes that it has entered boundary area a based on the detection signal from
The current boom rotation movement is read from the stored information in the RAM 20 and from the information in both areas, from the forward rotation area A where the load limit value is high to the right side rotation area B where the load limit value is low.
Recognize that it is a turning drive in the direction. Then, the load limit value read from the data ROM 22 at the time of entering the area is set as the load limit value of the forward turning area A (LM-
Switching from A) to the load limit value (LM-B) of right side turning area B, which is a turning area with a low load limit value,
Load limit value for the right side turning area B (LM-B)
and the current value of the load acting on the boom, and if the current value of the load exceeds the load limit value (LM-B), a command signal is output to the interface 15 to output a swing warning signal. As a result, the horn connected to the interface 15 sounds and an alarm is issued, but this alarm is different from the alarm that occurs when an overload occurs due to boom related operations (boom extension/contraction operation or hoisting operation). The strength, height, tone, presence or absence of intermittent movement, intermittent interval, etc. are changed, and it is possible to ensure that the driver recognizes without error that if the turning movement continues, the driver will be in an overload state. I'm starting to be able to do it. Therefore, by noticing the turning warning signal, the driver can recognize in advance that if the turning movement continues, an overload will occur, and therefore take appropriate overload avoidance operations such as stopping the turning in advance. This makes it possible to reduce as much as possible the problem of the turning motion stopping due to deep entry into the turning region where the load limit value is low. In addition,
Since the boundary area a is set in the forward turning area A, which has a high load limit value, even if a turning warning signal is output as described above, the actual load limit value is set within the forward turning area A's load limit value (LM -A), there is no risk of falling over even if the load limit value (LM-B) in right side turning area B is exceeded. Instead of or in combination with the above-described swing warning signal, a slow stop signal that gently stops the swing movement of the boom may be issued. In this case, the swing control valve that drives and controls the swing movement of the boom is configured with a proportional control valve equipped with a delay circuit, and while there is a latch output based on the slow stop signal, the proportional control valve gradually increases the amount of oil returned to the tank. However, in the end, the supply of driving oil to the swing drive actuator may be stopped, and the swing movement of the boom may be automatically and slowly stopped. In this case, if the deceleration speed is set so that the stop is completed within the boundary area a, the shock when turning is stopped can be greatly reduced, and moreover, before entering the turning area where the load limit value is low. Since the turning movement can be automatically stopped, it is possible to prevent as much as possible the problem that conventional overload prevention devices have, where the turning movement stops due to deep penetration into the turning area where the load limit value is low. be. Furthermore, in the present invention, the following configuration enables the return rotational movement of the boom after the rotational movement of the boom has been safely stopped as described above. That is, the limit switches 27 and 28 activated by the operation of the turning operation lever detect the direction of the turning operation by distinguishing it into a right turn and a left turn, and this detection signal is temporarily stored in the RAM.
20. The information corresponding to this turning operation direction is compared with the previously stored position information corresponding to the turning area before entering the boundary area, and if the two match, it is determined that the turning movement is returning to the safe side. The configuration is such that a command signal is output to the interface 15 in order to eliminate the stop signal for stopping the boom rotation. To explain this operation in detail in the case of the previous example, when the turning movement stops in the boundary area a while turning from the forward turning area A to the right turning area B and the operating lever is operated to turn left, the limit switch 28 detects that the control lever is being operated to turn left, and this detection signal is temporarily stored in the RAM 20. Next, CPU19
The positional information corresponding to the turning area (forward turning area A) before entering the boundary area stored in the RAM 20 is read out and compared with the information corresponding to the turning operation direction. Since the position information corresponding to the turning area before entering the boundary area is the forward turning area A, the verification result determines that the current turning operation direction is the return turning movement. As a result, CPU19 becomes interface 1.
Since a command signal for canceling the swing stop signal is output to the motor 5 and the stop signal disappears, the operator can return the boom BM to the direction of the forward swing area A by operating the lever. In addition, even if the turning movement stops when the vehicle crosses the boundary area a and enters the right side turning area B, the turning movement can be performed in the direction of the forward turning area A as a return turning movement to the safe side. It is best to configure it as follows. Next, a case will be described in which the turning movement is performed from a turning area where the load limit value is low to a turning area where the load limit value is high. For example, in Fig. 4, right turning area B
When the boom BM is rotated in the direction of the forward rotation area A, when the boom BM enters the boundary area a, the information processing device 23 recognizes the entry into the boundary area a based on the detection signal from the rotation position detector 5. At the same time, it is read from the memory information in the RAM 20 that the swing area where the boom BM was located immediately before was the right side swing area B, and from the information in both areas, the current boom rotation movement is on the right side where the load limit value is low. It is recognized that the turning movement is from turning area B toward forward turning area A where the load limit value is high. and the boundary area a
The load limit value read from the data ROM 22 at the time of entry is the load limit value of forward turning area A (LM-A).
The load limit value (LM-A) of the forward turning area A is compared with the current value of the load acting on the boom. With this configuration, the current load value is compared with a high load limit value when controlling the swing operation toward a safer side, so the swing movement of the boom is not unnecessarily restricted. It is something. The overload prevention device for construction machinery of the present invention allows work to be continued safely when the boom is located in a swing area with a high load limit value and has previously swiveled to a swing area with a low load limit value. Since it is possible to control the turning movement by determining whether or not the rotational movement is possible, it is useful as an overload prevention device for construction machinery whose load limit value changes step by step.

[Brief explanation of drawings]

Fig. 1 is a conceptual diagram showing each swing area and boundary area in a construction machine whose load limit value varies stepwise depending on the horizontal plane swing position of the boom BM, and Fig. 2 is a block diagram showing the configuration of the device of the present invention. FIG. 3 is an explanatory diagram of the configuration of a rotation position detector used in the apparatus of the present invention, and FIG. 4 is an explanatory diagram of control details of the apparatus of the present invention. BM...Boom, A, C...Turning area with high load limit value, B, D...Turning area with low load limit value, a, b, c, d...Boundary area.

Claims (1)

[Claims] 1. In a construction machine where the load limit value changes stepwise depending on the horizontal rotation position of the boom, the current load value is determined by comparing the load limit value that changes based on the rotation movement of the boom with the current load value. In an overload prevention device for construction machinery that is configured to issue a warning signal or a stop signal to stop related operations of the boom when the boom reaches a predetermined relationship with the load limit, A boundary area is established between the areas, and when the boom enters the boundary area from a swinging area with a high load limit value, the load limit value of the swinging area with a low load limit value and the current load value are set at the time of entering the boundary area. The overload of construction machinery is characterized in that the latter value is in a predetermined relationship with the former value, and a turning warning signal having a different warning method and warning pattern from the warning signal is emitted. Prevention device. 2 For construction machinery whose load limit value changes step by step depending on the horizontal rotation position of the boom, the load limit value that changes based on the boom rotation movement is compared with the current load value, and the current load value is compared to the load limit value. In an overload prevention device for construction machinery configured to issue a stop signal to stop boom-related operations when a predetermined relationship is reached, a boundary area is provided between a swing area with a high load limit value and a swing area with a low load limit value, and the boom When entering the boundary area from a turning area with a high load limit value due to turning movement, the load limit value of the turning area with a low load limit value and the current load value are compared at the time of entering the boundary area, and the latter value is compared with the current load value of the turning area with a low load limit value. 1. An overload prevention device for construction machinery, characterized in that the overload prevention device for construction machinery is configured to issue a slow stop signal to slowly stop the swinging operation of a boom when a predetermined relationship is reached with respect to a value.