JPS62296315A - Controller for electromagnetic switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION 3. Detailed Description of the Invention Field of Industrial Application The present invention relates to a control device for a magnetic switch that controls energization of a motor, heater, etc.

BACKGROUND OF THE INVENTION In recent years, with the development of electronic control devices, it has become easier to control energization of loads. A device that performs this energization control is a '4 magnetic switch. This electric/micro switch is very important as an interface that connects power devices such as motors and heaters with electronic circuits such as microcomputers (hereinafter referred to as microcomputers). In other words, the microcomputer is connected to the electromagnetic switch,
The motor etc. are connected to the electrical contacts of the electromagnetic switch, and these two are coupled by magnetic coupling.
Even if an excessive surge such as a lightning surge occurs in a motor, etc., the surge will not flow into the microcomputer, which is vulnerable to surges, and this will prevent the microcomputer from overshooting.This will turn the contacts on and off, making it possible to keep the windings open for long periods of time. When energized, the windings generate heat and their electrical resistance increases. Therefore, once
If you cut off the power to the winding of a 4-magnetic switch and turn off the contact, even if the winding is energized next time to turn on the contact, the current may not flow through the winding to close the contact and the contact may not turn on. . (Hereinafter, this phenomenon will be referred to as hot start.) In addition, it is necessary to send a current of at least several tens of milliamperes through the windings to open and close the contacts, which requires energy compared to the several milliamperes of current required to open and close a semiconductor type such as a triac. needed a lot of.

Furthermore, there is a problem in that safety cannot be ensured if the drive circuit of the seven-shield magnetic switch breaks down.

The present invention addresses the above-mentioned problems and aims to ensure reliable operation even during hot start, power saving, and high safety.

Means for Solving the Problems In order to solve the above-mentioned problems, the electromagnetic switch control device of the present invention is provided with a control section that intermittently energizes the windings.

Function: Due to the above-described configuration, the present invention generates only a small amount of heat in the windings, there is no hot start time order, and requires less power.Furthermore, in the event of a failure due to the electronic circuit (microcomputer) being left open, the heat generation in the windings is reduced. Safety is ensured by turning off the electric moat point of the electric/breaking switch due to the increase in electrical resistance.

Embodiment Hereinafter, a control device for an electromagnetic switch according to an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, an AC power source 1 is connected via a fuse 2 and a surge breaker 3 to a series connection of an electrical contact 4 of an electromagnetic switch and a heater 5, which is an object to be controlled. The AC power supply 1 also supplies power to a transformer 6, and a rectifier 7 is connected to the secondary side of the transformer 6. This rectifier 7 supplies power to the winding 10 of the electromagnetic switch via a transistor 12 which is a switching element. The on/off control of the transistor 12 is performed by the microcomputer 1, which is a control section.
1. The DC voltage of the rectifier 7 is applied to the input side of the microcomputer 11 via the switch 8 . A diode 9 and a capacitor 13 are connected in parallel with the winding 10.

The operation of the electromagnetic switch control device configured as described above will be explained. When the switch 8 is turned on, the microcomputer 11 is activated, causing a current shown in FIG. 2 to flow through the winding 10 of the electromagnetic switch via the transistor 12. That is, at the time of starting, the ON time is long (about 1 second), and then the duty ratio is 1/4.

This is because the longer the distance between the fixed iron piece consisting of the winding of the magnetic switching element and the movable iron piece of the electric contact part, the more magnetic force is required to drive the movable element. The shorter the distance, the less is needed, so when starting the electromagnetic switch, a large current is passed through the winding due to its long distance, and once it is turned on, the aforementioned distance is shortened and the on state is maintained with less circulation. Also, since it oscillates at a fast frequency (e.g. 80Hz), once it is turned on, even if there is no current for a short period of time, the movable iron piece cannot keep up with the operating speed, and even if it is operated by the oscillation circuit, the electricity of the switch remains unchanged. Contact 4 does not turn off and relay 5
tα is maintained.

As mentioned above, after starting the ′μ magnetic switch, there is little? Since the on state is maintained with a current of 1, the temperature rise in the winding 10 of the electromagnetic switch is small and the electrical resistance does not become high, so that it can be operated reliably even during a hot start. In addition, since electricity is supplied with a duty ratio of 1/4, a small amount of current is required, resulting in power saving. Furthermore, in the unlikely event that the microcomputer 11 fails and is left unenergized, the winding 10 of the electromagnetic switch
The current flows twice as much, and due to the increase in electrical resistance due to the warm rise, no current flows through the windings, and the electromagnetic switch is automatically turned off, stopping power supply to the heater, improving safety.

Effects of the Invention As described above, according to the present invention, it is possible not only to operate the device reliably even during a hot start, but also to save energy and further improve safety.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram of control values of an electromagnetic oscillator according to an embodiment of the present invention, and FIG. 2 is a waveform diagram of urine current in the same volume. 4...Electric contact of electromagnetic switch, 5...
Heater, 10...Winding of electromagnetic switch.

Claims (2)

[Claims] (1) An electromagnetic switch that generates magnetic force by energizing the windings to open and close electrical contacts, and an electromagnetic switch that includes a control unit that energizes the windings intermittently when the electrical contacts of the electromagnetic switch are turned on. control device. (2) The control unit energizes the winding of the electromagnetic switch at a certain period of time at the time of starting, and thereafter energizes the winding at a frequency that is smaller than at the time of starting. Switch control device.