JPS63264837A - Relay driving device - Google Patents

Abstract

PURPOSE:To immediately detect the occurrence of a soft stick and perform a countermeasure operation by outputting a relay on-signal then feeding an off-signal one or more times when the signal of a relay driving circuit section is off and the output signal of a relay contact point on/off detecting circuit section is on. CONSTITUTION:If a relay driving circuit section 1 shows that a relay 2 is off but the detection result of a relay contact point on/off detecting circuit section 4 shows that the relay 2 is on, the judging section of a microcomputer 5 judges that the relay 2 is in a soft stick state and operates as follows: The low-level signal voltage V3 is once generated by the relay drive signal generating section of the microcomputer 5, a current is fed to a relay coil 10 to absorb the contact point of the relay, then the high-level signal voltage V3 is again fed by the relay drive signal generating section. The contact point of the relay 2 in the soft stick state is thus absorbed. The occurrence of the soft stick is thereby detected at an early stage, and the recovery from the soft stick state can be quickly obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a relay drive device with improved relay durability.

Conventional technology This type of relay drive device is not publicly known, but when a relay contact causes soft stick (light welding), it detects this and turns on the relay drive signal to operate the contact. and remove the soft stick state.
A configuration has been proposed in which the relay is then turned off by applying an off signal.

Problems to be Solved by the Invention However, with this configuration, there are limited cases in which it can be determined that the relay is causing soft stick, and it takes time to recover from soft stick. have.

First of all, if you can determine that soft stick is occurring, even though the load is constantly monitoring the temperature of the heater and the relay is turned off to cut off the power to the heater. This is a case where the configuration is such that it can be seen that the temperature of the heater is rising. Secondly, it takes a long time to recover from soft stick.
This is because a certain amount of time is required to confirm the rise in temperature of the heater, and this problem arises because of the above configuration.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a relay drive device that solves the above-mentioned conventional problems and can detect the occurrence of soft stick at an early stage and quickly recover from the soft stick state.

Means for Solving the Problems In order to achieve the above objects, the present invention provides a relay for controlling power supply to a load, a relay contact on/off detection circuit for detecting on/off of the contacts of this relay, and a relay for driving the relay. and a relay drive circuit unit that supplies a drive signal, and when the relay drive signal of the relay drive circuit unit is off and the output signal of the relay contact on/off detection circuit unit is on, a signal that turns on the relay once. This is a relay drive device configured to output a signal and then supply a signal to turn off the signal once or multiple times.

Effect With the above configuration, it is possible to quickly determine whether or not the relay contact is causing soft stick by observing the relationship between the relay drive signal and the signal of the relay contact on/off detection circuit, and it is also possible to quickly determine whether the relay contact is causing soft stick. can be done reliably.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a concrete example of a circuit for implementing the same.

The general configuration is such that a load 3, a relay 2 that controls power supply to the load, a relay drive circuit section 1 and a relay contact on/off detection circuit section 4 that control the operation of the relay 2 are connected to a commercial power source 18. be.

The relay drive circuit unit 1 includes a microcomputer (hereinafter referred to as a microcomputer) 6, which has a determination unit that determines whether the contacts of the relay 2 are in a soft stick state, and a relay drive signal generation unit that generates a relay drive signal. , which includes resistors 6 and 7 and a transistor 8, generates a relay drive signal to drive the relay 2, receives a drive signal from the relay contact on/off detection circuit section 4, generates a relay drive signal, and then outputs a relay drive signal to drive the relay 2. Determine whether the contacts are in the soft stick state. 2 is relay coil 1
0 controls the power supply to the load 3 on and off. ■ divides the load voltage V2 with resistor 15.17,
This voltage is obtained by rectifying with the diode 16 and smoothing with the capacitor 14, and is the input voltage of the circuit C11 that constitutes the relay contact on/off detection circuit section. In addition, vrof is obtained by dividing the voltage vAc of the commercial power supply 18 by the resistor 12 and the resistor 13 by rectifying the voltage vAc by the resistor 22 and the diode 21, smoothing it by the capacitor 19, and stabilizing it by the Zener diode 2o. This is a reference voltage and also serves as the input voltage of the IC11. C11 is this voltage v4 and Vref
A signal of /1 level or low level is supplied to the determination section of the microcomputer 5.

The operation of this circuit will be explained below.

When the contact of the relay 2 is on, the voltage v2 of the load is equal to the voltage ■1 obtained from the commercial power supply 18. Further, when the contact of relay 2 is off, v2>vl. The relay contact on/off detection circuit section 4 detects that the voltage 2 of this load is V
The relationship between voltage v4 and reference voltage V
I watch it by comparing it with the ref.

That is, in this embodiment, when the contact of relay 2 is on, V4<Vref, and when it is off, V4>Vref. The IC 11 sends a low level signal voltage when the relay 2 is on, and a high level signal voltage when the relay 2 is off, to the determination section of the microcomputer 5 of the relay drive circuit section 1. The determination section of the microcomputer 6 receives this signal and causes the relay drive signal generation section to generate a relay drive signal voltage v3. When this signal voltage v3 is at a low level, a base current flows through the emitter, base, and resistor 6 to the transistor 8 of the relay drive circuit section 1, turning on the transistor 8, and current flows to the relay coil 1o of the relay 2. The current flows and relay 2 turns on. Further, when this signal is at a high level, the transistor 8 is off and no current flows through the relay coil 1o. Therefore, relay 2 is off.

Now, when the signal voltage 3 from the relay drive signal generator of the microcomputer 5 is at a high level and the output signal from the IC 11 is at a low level, that is, the instruction from the relay drive circuit section 1 is to turn off the relay 2. However, if the detection result of the relay contact on/off detection circuit section 4 indicates that the relay 2 is in the on state, the judgment section of the microcomputer 6 determines that the relay 2 is in the soft stick state and performs the following steps. Operate. Once a low level signal voltage v3 is generated from the relay drive signal generation section of the microcomputer 6, current is passed through the relay coil 10 to attract the relay contacts, and then a high level signal voltage v3 is generated from the relay drive signal generation section again.
supply. In other words, by attracting the contacts of the relay 2 in the soft stick state, the relay 2 recovers from the soft stick state and is then turned off.

Figures 3 and 4 explain this state.

FIG.

Fig. 3 shows the change over time of the signal voltage v3 of the relay drive signal generation section of the microcomputer 6 of the relay drive circuit section 1 and the input voltage (4) to the circuit C11 of the relay contact on/off detection circuit section 4.
The on/off state of the contacts of relay 2 is explained. Time t
1, the high/low changes of v3 match the high/low changes of v4, indicating that relay 2 is operating in a normal state. At time t1, even though v3 is high, (4) is low, and at this point, the contacts of relay 2 are in a soft stick state. At time t2, a current is applied to the relay coil 10 of the relay 2 to attract the contacts and remove the soft stick, and at time t3 the normal state is restored. However, the soft stick may not come off with just one suction operation as shown in FIG. The microcomputer 5 of the relay drive circuit section 1 constantly monitors the output status of the IC 11 of the relay contact on/off detection circuit section 4, and if the soft stick does not come off after just one suction operation, it suctions the relay contact multiple times until it comes off. It continues to operate. Figure 4,
FIG. 5 is a diagram explaining this state.

In Fig. 4, it is determined that the soft stick is in the state at time t1, and the soft stick comes off at the second ON signal, but in order to avoid re-welding, one more time is applied at the same time t2.
This indicates that it has been confirmed that the relay 2 operates normally by supplying the ON signal for the second time. In FIG. 5, the soft stick comes off at the fourth ON signal, indicating that it is operating normally.

In addition, in this way, the microcomputer 5 of the relay drive circuit section 1,
Once the soft stick state occurs, the program may be configured to supply an on signal one more time to confirm that it has returned to normal, or the program may be configured to turn relay 2 on and off a specified number of times. You may try to make it easier.

Effects of the Invention As described above, by taking the logical product of the relay contact on/off detection circuit section and the relay drive circuit section 9 outputs, it is possible to immediately detect soft stick in the relay. It is possible to provide a relay drive device that can perform soft stick countermeasure operations and improve the durability of the relay.

[Brief explanation of the drawing]

Fig. wJ1 is a block diagram showing an embodiment of the relay drive device of the present invention, Fig. 2 is a specific circuit diagram of the same relay drive device, and Figs. 3, 4, and 6 show the output voltage of the relay drive circuit section. FIG. 3 is a voltage waveform diagram showing terminal voltages of relay contacts. 1... Relay drive circuit section, 2... Relay, 4... Relay contact on/off detection circuit section. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 5...Microcomputer! Fig. 3 Fig. 4° Fig. 5

Claims (1)

[Claims] It includes a relay that controls power supply to the load, a relay contact on/off detection circuit that detects whether the relay contact is on or off, and a relay drive circuit that supplies a relay drive signal that drives the relay. , when the relay drive signal of the relay drive circuit section is off and the output signal of the relay contact on/off detection circuit section is on, a signal to turn the relay on is outputted, and then a signal is outputted to turn it off. 1
A relay drive device that supplies power once or multiple times.