JPS6243026A - Driver for relay - Google Patents

Abstract

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

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a relay drive device that extends the life of the relay.

Conventional technology Conventionally, a relay drive device in which a relay contact and a load are connected in series to an AC power source detects the temperature of a heater 2 serving as a load using a temperature detection element 1, as shown in FIGS. 3 and 4. The signal is input to the temperature control device 3. The temperature control device 3 has a relay random drive means 6 that outputs a drive signal of a transistor 60 for turning the relay 4 on and off uniformly and in a varying manner in all phases of the alternating current. In other words, the relay random drive means 6 turns on the relay 4 with a positive AC voltage, then turns it on with a negative voltage,
As a whole, all phases are operated uniformly with variations.

This is intended to reduce electrical wear on the contacts 7 of the relay and improve durability.

Next, the durability test is as follows.

As shown in FIG. 4, seven relays 4 are forcibly turned on and off by a durability test circuit 8 having random drive means 6 for relays, and a counter 1o is connected in parallel with the relay coil 9 to conduct a durability test. The number of outputs from the circuit 8 is counted. In addition, a blank/
11 and actually count the on/off circuit of the relay contact 7.

By doing this, when the relay contact 7 does not open or close even though current is flowing through the relay coil 9, this can be known from the difference in counts between the counter 1o and the counter 11.

According to FIG. 6, it can be seen that mud 6 caused light welding once out of 10 after about 500,000 cycles. Similarly, it can be seen that up to 8 out of 10 pieces become more susceptible to welding after about 900,000 cycles.

Problems to be Solved by the Invention In the conventional device described above, if light welding occurs on the relay contact 7 that is turned once, even if the temperature control device 3 outputs an off signal and the relay coil 9 is de-energized, the relay contact remains intact. 7
will not turn off due to welding.

If you leave it as is, the temperature will rise. Although the temperature detection element 1 continues to output a signal to turn off the relay, the relay contacts remain slightly welded, and the temperature of the object to be heated continues to rise, potentially resulting in a dangerous situation such as a fire.

In view of this, the present invention provides a relay drive device that forcibly turns off the relay contacts in the case of light welding, prevents abnormal temperature rise, and improves the durable life of the relay. It is something.

Means for Solving the Problems In order to achieve this object, the present invention includes an abnormal temperature detection means for detecting abnormal temperature in the temperature control device of the conventional circuit, and a relay that is forced several times after detecting the abnormal temperature. This is achieved by providing a relay forced drive means to turn on and off.

With this configuration, if light welding occurs on the relay contacts, it detects an abnormality in the temperature of the object, forces current to flow through the relay coil that is off, and applies mechanical vibration to the relay contacts. Can remove light welding of relays.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 and 2.

In the figure, 16 is an AC power supply, 16 is a heater serving as a load, and 17 is a relay, with a relay contact 18 and a relay coil 19.
have. Relay contact 18 and heater 16 are connected in series to AC power supply 15. 20 is a temperature sensing element;
It is attached to the controlled object to which the heater 16 is attached.

21 is a temperature control device to which a signal from the temperature detection element 2o is input. 22 is a resistor connected to the temperature control device 21, one end of which is connected to the AC power source 16. 23 is a DC power source for the relay coil 17 and the temperature control device 21.

24 is a relay coil 19 which is controlled by the output of the temperature control device 21.
It is a transistor that turns on and off.

The temperature control device 21 described above includes an abnormal temperature detection means 26 that detects an abnormal temperature higher than the set temperature;
When an abnormal temperature is detected, a relay forced drive means 26 forcibly turns on and off the relay 17, and when the relay forced drive means 26 outputs a signal to turn on and off the relay,
It has a relay random drive means 27 that randomly drives the relay 17 with respect to the positive/negative or phase of the power supply according to the timing, and the heater 1e is controlled by the output of the relay random drive means 27. Also, temperature control device 21
The output of is connected to random drive means 27 of the relay.

The operation of the apparatus configured in this manner will be described below.

In normal operation, the temperature of the controlled object is detected by the temperature detection element 20, and the random drive means 2 of the relay of the temperature control device 21 is activated.
7 controls the heater 16 to control the temperature of the object to be constant.

However, if light welding occurs on the relay contacts 18, the temperature control device 21 issues an off signal, and the relay coil 19
The relay contact 8 remains on even though it is not energized. Therefore, the temperature further increases. Then, the temperature detection element 2o detects an abnormal temperature, and the relay forced drive means 26 is activated by the abnormal temperature detection means 26 to turn on the relay 17 which has been turned off. Then, a mechanical signal is applied to the lightly welded state of the relay contact, which releases the lightly welded state. Next, when relay 17 is turned off,
Relay contact 18 is turned off. If this cannot be done once, the relay forced drive means 26 may be used to turn on and off several times.

Effects of the Invention As described above, with the conventional equipment, even light welding of relays made it impossible to control IW, but with the equipment of the present invention, countermeasures are taken against light welding, so the lifespan will be further extended. , an extremely useful relay driving device can be provided.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the device of the present invention, and FIG.
3 is a block diagram, FIG. 4 is a conventional relay durability test circuit diagram, and FIG. 5 is a diagram showing the results of the durability test. 15... AC power supply, 16... Heater, 1
7...Relay, 18...Relay contact,
19...Relay coil, 20...Temperature detection element, 21...Temperature control device, 26...Abnormal temperature detection means, 26...Relay forced pulling means,
27...Relay random drive means. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure/2θ Figure 2 Figure 4 Figure 5

Claims (1)

[Claims] A relay contact and a heater are connected in series to an AC power source, a temperature detection element is attached to the controlled object to which the heater is attached, and its input is connected to a temperature control device, and the temperature control device is connected to an abnormal temperature detection means and a relay. A relay drive device that has a forced drive means and a random drive means for a relay, and controls a heater by turning on and off the relay using the output thereof.