JPS6346418Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an overload prevention device used as a control device for conveyor facilities.

Conventionally, when conveying objects by a conveyor, if the conveyor drive motor becomes overloaded due to the amount of conveyance being larger than the conveyance capacity, a stop buzzer sounds and the overload is stopped. The motor in question and related facilities, such as the motor for driving the conveyor that supplies the conveyor driven by the motor, were shut down. This conventional overload detection is performed using a thermal relay, whose contacts are bimetallic and sensitive, so that when the motor becomes overloaded, it is activated by the overcurrent flowing through the motor. The bimetal heats up and deforms, closing the relay contact and detecting an overload condition. However, until the bimetal deforms and closes the contact, the overload condition continues, causing objects to be transported to become clogged, especially at the entrance of the bucket elevator. for that,
The operator has to re-drive the conveyor or other facility after the cumbersome task of removing and cleaning the clogged material, resulting in a reduction in conveyance processing efficiency. Furthermore, after restarting the facility, the operator may feed material to the conveyor driven by the overloaded motor in order to reduce the load on the motor so that the motor does not overload again. Operations such as slowing down the transport speed of the conveyor used to reduce the amount of waste transported have resulted in a reduction in the processing efficiency of the facility.

This invention was made in view of the above circumstances,
The purpose of the present invention is to provide an overload prevention device that can improve the conveyance efficiency of a conveyor. The reason is that a current detection device is used to detect the load state before the load condition is reached. Further, the control device is controlled by a signal that detects the load state to reduce the load on the motor.

The present invention will be explained below based on the drawings.

FIG. 1 is a block diagram showing the basic principle configuration of the overload prevention device according to the present invention, in which 1 is a motor for driving a conveyor whose load state is to be detected, 2 is an overload prevention device, and 3 is a control object. The overload prevention device 2 includes a current detection device 4 and a control device 5. Any number of motors 1 whose load conditions are to be detected can be connected to the overload prevention device 2. The current detection device 4 detects the load state of the motor 1 before the motor 1 becomes overloaded to the extent that it is overloaded and stopped, and in the embodiment described later, a meter relay type ammeter is used. , the principle is that an adjustable contact (hereinafter referred to as the first contact) is mounted on the scale plate,
Another contact (hereinafter referred to as the second contact) is attached to the pointer, and the pointer moves as the current value changes, and when the current value reaches the set value, the second contact contacts the first contact and the relay contact is activated. The system is such that a signal is output when the gate is closed. Control device 5
When the current detecting device 4 outputs a signal indicating that the current detecting device 4 has detected an overload condition of the motor 1, it receives that signal and determines that the motor 1 is in an overload condition, and then controls the controlled object 3. It has a function of emitting a signal to the controlled object 3 so that it operates to reduce the load condition of the motor 1. The controlled object 3 may be a facility that supplies materials to a conveyor driven by the motor 1, such as a hopper shutter or a belt conveyor drive motor.

Next, one embodiment of the present invention will be described based on FIGS. 2 and 3.

Figure 2 shows a part of the conveyor facility, where 6 is a storage tank, 7 is a belt conveyor, and 8 is a storage tank.
9 is a motor for driving the belt conveyor 7 as a controlled object, 9 is a bucket elevator that is relatively prone to overload, 10 is a motor for driving the bucket elevator 9 as a motor whose load state is to be detected, and 11 is a chute. It is. In the storage tank 6,
Grain 12 as a material to be transported is stored, and this storage tank 6 supplies the grain 12 to a belt conveyor 7. A shutter 13 is provided at the discharge port of the storage tank 6, and the shutter 13 operates depending on the opening degree of the discharge port of the storage tank 6 when the grain 12 is supplied from the storage tank 6 to the belt conveyor 7. It is said that the supply amount can be adjusted. The belt conveyor 7 conveys the grain 12 received from the storage tank 6 and supplies it to the bucket elevator 9, and its conveyance speed is variable by controlling the rotational speed of the motor 8. ing. Bucket elevator 9 is
The grain 12 supplied from the belt conveyor 7 is supplied to a chute 11, and the grain 12 is transported and supplied to the next processing facility by this chute 11. 14 is a control panel, and this control panel 14 includes a drive motor 8 for the belt conveyor 7 and a drive motor 1 for the bucket elevator 9.
0, the conveyor facilities such as the shutter 13 of the storage tank 6 are centrally controlled. In FIG. 3, reference numeral 15 denotes an overload prevention device, which constitutes a part of the control panel 14, and here includes a meter relay type ammeter 16 and a microcomputer control device 17. The microcomputer control device 17 and the speed control device 18 constitute the control device. Meter relay type ammeter 16
As mentioned above in the explanation of the principle configuration,
It is possible to set the current value, and here, the current value that flows through the motor 10 when the motor 10 for driving the bucket elevator 9 is in a light overload state before the overload state reaches such an overload state that the overload stop occurs. The meter relay type ammeter 16 outputs a signal when the current flowing through the motor 10 exceeds this set value. The microcomputer controller 17 receives a signal from the meter relay ammeter 16, determines that the motor 10 is overloaded when this signal continues for a predetermined period of time, and outputs a speed change command signal to the speed controller 18. As mentioned above, if the signal output from the meter relay ammeter 16 does not continue for a predetermined period of time, it will not be determined that the motor 10 is in an overload state. Temporary current flowing from the meter relay type ammeter 16 due to a transient current flowing through the motor 10 or a pulsating overload in which the motor 10 is temporarily overloaded for some reason. This makes it possible to prevent erroneous operation in which an overload condition is determined based on the signal. Speed control device 18
When receiving the speed change command signal from the microcomputer control device 17, the controller reduces the rotational speed of the driving motor 8 of the belt conveyor 7, and reduces the amount of grain 3 supplied to the bucket elevator 9.
It functions to reduce the load condition of the motor 10 which is in an overload condition. In addition to the above-mentioned functions, the microcomputer control device 17 also has a timer function, whereby the motor 8 for driving the belt conveyor 7 is activated after a certain period of time after the motor 10 escapes from the overload state. The rotation speed is automatically returned to the initial speed before the overload prevention process was performed. In addition, in case the motor 10 of the bucket elevator 9 breaks down and the overload condition cannot be overcome even after the above-mentioned overload prevention process is performed, a thermal relay (a thermal relay ( (not shown)
is used, and the conveyor facility is shut down if the overload condition continues for a predetermined period of time.

The effects of the embodiment configured as described above will be explained.

When the amount of grain 12 supplied from the belt conveyor 7 is large and a heavy load begins to be applied to the drive motor 10 of the bucket elevator 9, the contacts of the meter relay type ammeter 16 begin to approach accordingly, and the motor 1
The contact is closed before the overload condition reaches such an extent that 0 becomes an overload stop. At the same time, a signal is output from the meter relay ammeter 16 to the microcomputer control device 17, and when this signal continues for a predetermined period of time, the microcomputer control device 17 outputs a speed change command signal to the speed control device 18, The speed control device 18 reduces the rotational speed of the motor 8. Then, the amount of grain 12 supplied to the bucket elevator 9 is reduced, the load state of the motor 10 is reduced, the overload state is automatically released, and the motor 8 is automatically restarted after a certain period of time after exiting the overload state. The rotational speed of the conveyor is returned to the initial speed, and the conveyor does not have to stop immediately upon occurrence of an overload condition, so it is no longer necessary to stop the conveyor, and the conveyance efficiency of the conveyor is improved. Furthermore, since the meter-relay type ammeter 16 is used as a current detection device for detecting the load condition of the motor 10, the operator can check the current flowing through the motor 10 at any time, and more appropriate work can be performed. becomes.

As explained above, according to the present invention, the load condition is detected before the motor becomes overloaded to the extent that it stops, and the overload condition of the motor is reduced. It is possible to prevent processing from being interrupted as much as possible, improving conveyor processing efficiency, and reducing the troublesome work caused by overload stops, allowing operators to free up their time for other tasks. Moreover, it can be used to fully automate conveyor facilities.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the basic principle configuration of an overload prevention device according to the present invention. FIG. 2 is a schematic configuration diagram showing a part of the conveyor facility. FIG. 3 is a block diagram showing an example in which the overload prevention device according to the present invention is applied to the conveyor facility shown in FIG. 2. 1, 10... Motor (motor whose overload state is detected), 2, 15... Overload prevention device, 3...
Controlled object, 4... Current detection device, 5... Control device, 8... Motor (controlled object), {17... Microcomputer control device, 18... Speed control device} (control device), 16... Meter Relay type ammeter (current detection device).

Claims (1)

[Claims for Utility Model Registration] An overload prevention device used as a control device in a conveyor facility where the motor is stopped when the conveyor drive motor becomes overloaded, the motor being stopped. a current sensing device connected to detect current to the motor, the current sensing device having contacts adjustably arranged to close the circuit before a load condition is reached; and the current sensing device is actuated. an overload prevention device comprising: a control device configured to reduce the load on the motor by a signal emitted by the motor;