JPH0570098A - Load equalizer - Google Patents

Abstract

PURPOSE:To provide a lifting tool preventing the downward pressing and having high reliability and a simple structure by providing a means judging that the detection value of the weight of a load is smaller than the weight under no load, and stopping the downward movement of a lift system based on the signal from the judging means. CONSTITUTION:A lift system 1 lifting or lowering a load 4, a lift driving motor 2 driving it, a load detector 14 detecting the weight of the load 4, a weight memory section storing the detected weight of the load 4, a speed detector 19 detecting the speed of the lift system 1, and a speed command unit commanding the speed of the lift system 1 are provided. The size and polarity of the signal from the load detector 14 are judged by a load judgment section, and the travel speed of the lift system 1 is calculated to control the travel of a load equalizer. When the load detection value of the load detector 14 is smaller than the value under no load, the load judgment section judges the load as the reverse load and outputs an abnormality signal to an arithmetic section, and the operation of the lift system 1 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a parallelogram linkage type mechanism which drives a actuator by elevating and lowering a load by using an actuator such as an electric motor, and a load detector for detecting the weight of the load. The present invention relates to a safety circuit of a balanced load device in which a worker has a command device that commands a speed or a position and can raise and lower a load by operating the command device.

[0002]

2. Description of the Related Art As a safety circuit of this type of load balancing device, there are Japanese Utility Model Laid-Open No. 58-71088 (arm crane) and JP-A-1-303296 (safety circuit of balancing device). The device of Japanese Utility Model Laid-Open No. 58-71088 is an arm type crane in which a parallelogram linkage type mechanism is used to elevate and lower the load by using an actuator such as an electric motor. When the hook moves upward with respect to the vertical arm, the switch operates in conjunction with the movement of the hook to stop the lowering operation of the vertical arm.

Further, the safety circuit disclosed in Japanese Patent Laid-Open No. 1-03296 discloses a balanced cargo handling apparatus having a load detecting means for detecting the weight of a load in a lifting mechanism, and a speed from a speed command device for instructing the load balanced cargo handling apparatus to go up and down. When the command signal is in the direction of increasing the load, the speed command signal is operated so as not to be transmitted to the drive circuit, so that it will not operate in the rising direction when a load greater than the rated load is hung. is there.

[0004]

In the prior art, for example, Japanese Utility Model Laid-Open No. 58-71088 discloses a switch interlocked with a hook when the device is on the floor surface while it is descending or hits another device or object. It operates so as to stop the descending operation, and safety measures are taken against a collision or the like at the time of descending. Further, in Japanese Patent Laid-Open No. 1-303296, the device does not rise when the weight of the load lifted by the lifting means exceeds the rated load, and the device can be operated in the descending direction. Although it has been taken, safety measures have not been taken against collisions when descending.

When this type of parallel link type load balancing device is actually used in a line, a normal crane / hoist or the like hoists the load with a wire or a chain, so that there is no need for protection especially against a collision at the time of descending. Although it does not affect the device itself, since the lifting mechanism according to the present invention employs a parallel link type mechanism, a force is generated in the descending direction even when descending, and protective measures are required in the descending direction as well. Become.

[0006] Here, a conventional example, actual development Sho 58-710.
In 88, when a force is applied to the hanger (hook) or the like in the descending direction, the hanger (hook) moves in the ascending direction to operate the switch, so that it is taken as a protective measure, but since it is composed of a mechanical system, it is long. It may not operate smoothly due to rattling or wear of the mechanical system due to continuous use.In such a case, even if force is applied in the descending direction, it will not stop and the device will be destroyed or the worker will be unsafe. It can be a situation. In addition, the structure around the hanging tool (hook) becomes complicated, and the operation box for the lifting mechanism also becomes large. Further, in a load balancer having a built-in load detector, it is necessary to put all of them in the operation box, which further complicates the configuration.

The present invention has been made to solve the above problems, and in the load balancing device for parallel linking, the lifting device of the elevating mechanism is provided with load detecting means for detecting the weight of the load. Therefore, when a force in the compression direction is applied to the lifting device (hook) of the lifting mechanism by using the load detection signal from the load detection means, for example, when the load is lowered, the load is pressed against the floor surface or other nearby devices. In the case of collision with the device, the fact that the polarity of the signal from the load detecting means is opposite to the normal direction is used. Alternatively, by stopping the operation in the reverse direction such as the downward pressing of the elevating mechanism, the configuration in the vicinity of the hanging tool becomes simple. Further, the operation box can be downsized, and further, the reverse load detection circuit having a longer life without using a mechanical system is configured to provide a load elevating device that is safe for both the device and the operator.

[0008]

A load lifting device according to the present invention includes a load lifting mechanism for lifting a load, a drive mechanism for driving the lifting mechanism, a load detector for detecting the weight of a load, and a load detector. A weight storage unit that stores the weight of the load, a speed detector that detects the speed of the load lifting mechanism, a speed commander connected to the operating lever that the operator commands the speed of the lifting mechanism, and a load detector A load determination unit that determines the magnitude and polarity of the signal and a calculation unit that calculates the lifting speed of the lifting mechanism based on these output signals control lifting of the load balancing mechanism.

[0009]

The elevating speed when the elevating mechanism suspends a load to perform an elevating operation is input from the speed command device to the speed computing section as a speed command signal in response to a change in the operation amount of the operating lever by the operator. The weight of the suspended load is detected by the load detector, and is temporarily stored as the weight of the load in the weight storage unit that stores the weight of the load. The deviation between the stored weight and the detected weight is taken to obtain the speed command signal. Is input to the calculation unit in the same manner as. The operation unit calculates the speed for the lifting mechanism, and in the operation mode in which the command from the speed commander is valid, the load lifting mechanism is driven by the speed command signal that changes in proportion to the operation amount of the operating lever. An elevating command is output to the section, and the elevating mechanism carries out an elevating operation according to the elevating command. In the equilibrium mode in which the lifting / lowering operation is performed with the weight stored in the weight storage unit as the target, the deviation between the weight stored in the weight storage unit and the weight of the load detected by the load detector is calculated, and this deviation is calculated. As a lifting command, the lifting mechanism carries out a lifting operation.

At this time, if the value of the load detection signal detected similarly to the load detector is smaller than the value in the no-load state, the load determination unit determines that the load is a reverse load and outputs an abnormal signal to the calculation unit. Then, the operation of the lifting mechanism is stopped.

By detecting the case where the lifting mechanism collides with the floor surface in this way, it is possible to avoid a situation in which a force is generated in the descending direction to destroy the lifting mechanism or to cause a danger to the operator. it can.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS.

A parallel link type lifting mechanism 1 is driven up and down by a lifting driving motor 2 and a gear mechanism 3 to move up and down.
A suspending tool 5 for suspending the load 4 is provided at the tip of the load 4, and the load 4 is suspended. Further, an operation lever 7 of a speed command device 6 for commanding the ascending / descending speed of the elevating mechanism 1 is provided, and a speed command signal S from the speed command device 6 is input to a determination unit 8 and a V / F converter 9 is also provided. Digitally converted by
It is input to the target counter 12 through the mode selection unit 11 of 0, and is input to the position calculation unit 13 as the target position of the lifting mechanism 1.

A suspender 5 for suspending the load 4 is attached to the tip of the lifting mechanism 1 via a load detector 14, and the weight W of the load 4 is detected by the load detector 14 and used as a load signal WA. The load signal WB is digitally converted by the A / D conversion unit 15 and is input to the weight storage unit 16, the deviation detection unit 17, and the load determination unit 18.

The judging section 8 receives a signal from the position calculating section 13 of the calculating section 10 and outputs a storage signal R to the weight storing section 16, and the deviation detecting section 17 outputs the target weight WC from the weight storing section 16. Take the deviation of the current weight WB from the load detector,
The deviation signal WR is output to the arithmetic unit 10. Further, the load determination unit 18 receives a signal from the load detector 14, determines whether the load detection value is normal or abnormal, and outputs an abnormal signal to the position calculation unit 13.

The ascending / descending speed of the ascending / descending mechanism 1 is detected by the speed detector 19 and fed back to the drive unit 20 of the ascending / descending mechanism 1 as a speed feedback signal SF, so that the ascending / descending mechanism 1 is controlled in speed. Further, the position of the elevating mechanism 1 is detected by the position detector 21 and input to the current counter 22 of the calculating unit 10, and is input to the position calculating unit 13 as the current position of the elevating mechanism 1. The target position is further input to the position calculation unit 13 from the target counter 12, and the speed command for the lifting mechanism is converted into an analog signal by the D / A conversion unit 23. Then, the driving unit of the lifting mechanism 1 outputs the speed command signal X0. It is output to 20. Next, the operation of the safety circuit of the load lifting device according to the present invention will be described.

When the operator operates the operation lever 7, a speed command signal S proportional to the operation amount of the operation lever 7 is output from the speed command device 6, digitally converted by the V / F converter 9, and the arithmetic unit 10 is operated. By performing the calculation by outputting the drive signal X0 for the elevating mechanism 1 to the driving device 20 of the drive motor 2, the elevating mechanism 1 executes the elevating operation at a speed proportional to the operation amount of the operation lever 7.

At this time, the speed command signal S from the speed commander 6 connected to the operation lever 7 is supplied to the calculation unit 10 as V / F.
A command signal SA digitally converted by the converter 9 is input through a mode selection unit 11, and this command signal SA is input to a target counter 12 that gives a position target for the lifting mechanism 1, and the position calculation unit 13 determines the target position. Entered in.
Further, the current position of the elevating mechanism 1 is input from the position detector 21 to the current counter 22 as a position detection signal XF, the current position is counted, and the current position signal X is input to the position calculator 13. In the position calculation unit 13, the target counter 1
The target position from 2 and the current position from the current counter 22 are compared / calculated, a lift command to the lift mechanism 1 is output, and the D / A converter 23 performs analog conversion to drive the lift mechanism 20. By outputting the drive signal XO to
The drive motor 2 of the elevating mechanism 1 is driven to elevate the elevating mechanism 1.

The elevating mechanism 1 is driven up and down based on the drive signal XO output from the position calculator 13, and the ascending / descending speed is detected by the speed detector 19 and the driver 20 of the elevating mechanism 1 is detected.
Is fed back as a speed feedback signal SF to control the speed of the lifting mechanism 1.

When the operator operates the lifting mechanism 1, the mode converter 11 is selected to be in the operation mode side, and the lifting mechanism 1 is driven up and down by operating the operating lever 7. Here, when the speed command signal S becomes small and the change in the position of the lifting mechanism 1 becomes small, the position calculation unit 13 outputs the signal SH, and the determination unit 8 outputs the weight storage signal R to the weight storage unit 16. Then, the weight storage unit 16 stores the weight of the load 4 suspended by the lifting mechanism 1, the mode conversion unit 11 is selected to the balance mode side, and the operation mode shifts to the balance mode.

The weight of the load 4 suspended by the elevating mechanism 1 is detected by the load detector 14, and the D / A is output as the load signal WA.
The weight of the load 4 is stored in the weight storage unit 16 as a weight signal WB by being converted into an analog signal in the conversion unit 15.
Here, the weight stored in the weight storage unit 16 is input to the deviation detection unit 17 as the target weight WC to be lifted by the lifting mechanism 1 and compared with the current weight of the load 4. The deviation obtained by the deviation detector 17 is input to the calculator 10 as a deviation signal WR to drive the lifting mechanism 1 up and down.

At this time, the load signal WB detected by the load detector 14 is compared and judged by the load judging section 18, and the force applied to the suspending tool 5 of the lifting mechanism 1 suspends the load 4. When it is, it is judged to be normal. However, when the force applied to the hanger 5 is in the opposite direction (when the polarity of the load detection signal is in the opposite direction and when the weight is less than or equal to no load), the position calculator 13 is caused to stop the lifting mechanism 1. A signal T is output and the operation of the elevating mechanism 1 in the descending direction is stopped.

As a result, it is possible to prevent the lifting tool 1 from pressing the load 4 while the elevating mechanism 1 suspends the load 4, and to prevent the elevating mechanism 1 from colliding with the floor surface. As described above, according to the present embodiment, the lifting mechanism stops the descent when the weight of the load is no load or less, so that the lifting mechanism can be prevented from being pressed in the descending direction. Further, since the mechanism for detecting the reverse load does not use a mechanism, the suspender has a more reliable and simple structure. Further, the operation box can be downsized, and by not using a mechanical system, a reverse load detection circuit with a longer life can be configured to improve the safety of the device, and a worker can be provided with a safe load lifting device. .. (Other embodiments)

The detected value of the reverse load should be a value with a little margin as compared with the case where the polarity of the load detection signal is in the reverse direction. And the weight under no load shall be less than the weight including hanging equipment.

[0025]

As described above, by carrying out the present invention, the descent is stopped when a reverse load is applied to the elevating mechanism, so that the elevating mechanism can be prevented from pressing in the descending direction. Further, since the mechanism for sliding the reverse load is not used, the suspender has a more reliable and simple structure. Further, the operation box can be downsized, and a reverse load detection circuit having a long life can be configured by not using a mechanical system.

For this reason, when the elevating device is used in an actual production line, it is not necessary to press the elevating device when suspending a load that is easily broken, and the operator can operate it with peace of mind. Also, the load detector itself, which detects the weight of the load, is okay for the force in the tensile and compression directions, but it is not recommended to apply force in the diagonal direction, it also prevents the load detector from being broken, and the safety of the device. It is also possible to provide a safe load lifting device for workers.

[Brief description of drawings]

FIG. 1 is a mechanism configuration diagram of a first embodiment of the present invention,

FIG. 2 is a control block diagram of the first embodiment of the present invention,

FIG. 3 is an explanatory diagram of a load detection value of a load according to the first embodiment of this invention.

[Explanation of symbols]

1 ... Lifting mechanism, 2 ... Lifting drive motor, 4
… Load, 6… Speed commander, 7… Operating lever,
8 ... Judgment part, 9 ... V / F converter, 10 ... Calculation part, 11 ... Mode selection part, 12 ... Target counter, 13 ... Position calculation part, 14 ... Load detector, 1
5 ... A / D converter, 16 ... Weight storage section, 17 ...
Deviation detection unit, 18 ... Load determination unit, 19 ... Speed detector, 20 ... Drive device, 21 ... Position detector, 2
2 ... Current counter, 23 ... D / A converter.

Claims (3)

[Claims] 1. A mechanism for moving a load up and down, a means for driving the load lifting mechanism, and a means for detecting the position of the lifting mechanism,
Position control means for lifting mechanism, means for detecting weight of load, position control means for lifting mechanism, means for detecting weight of load, means for storing weight of load, stored value of weight of this load In a load balancing device that operates with the target as a target, it has means for judging that the detected value of the weight of the load is smaller than the unloaded weight, and the operation of the lifting mechanism in the descending direction is stopped by a signal from this judging means. A load balancer having a control method. 2. A mechanism for moving a load up and down, a means for driving the load lifting mechanism, a means for detecting the speed of the lifting mechanism,
In a load balancing apparatus that operates with the speed control means of the lifting mechanism, the means for detecting the weight of the load, the means for storing the weight of the load, and the stored value of the weight of the load as a target, the detected value of the weight of the load. A load balancing device, characterized in that it has a means for judging that the weight is smaller than the unloaded weight, and has a control method for stopping the operation of the elevating mechanism in the descending direction in response to a signal from this judging means. 3. A means for determining that the polarity of the detected value of the weight of the load is opposite to the direction in which the load is hung, and a signal from this determination means stops the operation of the lifting mechanism in the descending direction. The load balancing device according to claim 1 or 2.