JPH04338609A - Solenoid driving circuit - Google Patents

Abstract

PURPOSE:To enable the reuse without replacement of parts and minimize the damage by arranging the constitution such that the temperature fuse of a solenoid does not operate even when a signal generating circuit operates. CONSTITUTION:A solenoid driving circuit which has a solenoid 12, a switching element 15, a signal generating circuit 16, which generates an ON signal for turning on the solenoid 12, and a table metastable multivibrator circuit 17, which starts the operation by the ON signal of the signal generating circuit 16 and outputs an ON signal for turning on the solenoid 12, and then outputs an OFF signal for turning off the solenoid.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solenoid drive circuit.

0002

2. Description of the Related Art A conventional solenoid drive circuit will be described below. In Figure 3, 1 is an AC power supply, 2 is a DC power supply that rectifies the AC power supply 1 to obtain a DC output, 3 is a solenoid, 4 is a thermal fuse that operates when the temperature of the solenoid 3 rises abnormally, and 5 is a thermal fuse that is activated when the temperature of the solenoid 3 rises abnormally. A diode bridge converts the applied voltage into DC; 6 is a switching element that drives the solenoid 3; 7 is a signal generation circuit that outputs a signal to control the switching element 6.

In the solenoid drive circuit configured as described above, the signal generating circuit 7 applies an ON signal for approximately 1 second to the switching element 6, causing a large current to flow through the solenoid 3 in a short period of time, causing it to operate with a strong force. was there.

In the case of this type of solenoid drive circuit, a large current is passed through the solenoid 3, so if the solenoid 3 becomes continuously energized due to a malfunction or failure of the signal generating circuit 7, the solenoid 3 will heat up and there is a risk of fire. Therefore, the thermal fuse 4 was used to cut off the current.

[0005]

[Problems to be Solved by the Invention] However, in the above configuration, even if the signal generation circuit 7 malfunctions due to extremely large external noise and becomes continuously energized, the thermal fuse 4 is activated, and the thermal fuse 4 is connected to the solenoid. 3, it would be necessary to replace the solenoid 3 as well as the thermal fuse 4, which would be very uneconomical.

The present invention solves the above conventional problems, and even when the signal generating circuit 7 malfunctions due to extremely large external noise and becomes continuously energized, the signal generating circuit 7
If the solenoid continues to output an on signal for a certain period of time, the monostable multivibrator circuit outputs an off signal to prevent the solenoid from turning on for a certain period of time.
The first purpose is to prevent the thermal fuse 4 from operating.

Furthermore, if the signal generation circuit 7 is a digital circuit such as a microcomputer, there is a possibility that other malfunctions may have occurred, so sending a reset signal to the signal generation circuit 7 returns all operations to the initial state. The second purpose is to restore the area and minimize damage.

[0008]

Means for Solving the Problems In order to achieve the above object, a first means of the present invention includes a solenoid, a switching element for energizing the solenoid, and a switching element for controlling the switching element to turn on the solenoid. a signal generating circuit that generates an on signal to turn on the solenoid; and a signal generating circuit that starts operation based on the on signal of the signal generating circuit and generates an on signal that turns on the solenoid for a certain period of time longer than the on signal of the signal generating circuit. and a monostable multivibrator circuit that outputs an off signal to turn off the solenoid after the output, and the solenoid is turned on only when the outputs of the signal generation circuit and the monostable multivibrator circuit are both on signals. This is based on a solenoid drive circuit configured as follows.

A second means is that when the output of the monostable multivibrator circuit is switched from the on signal to the off signal and when the output of the signal generating circuit is outputting the on signal, the signal generating circuit is switched from the on signal to the off signal. The solenoid drive circuit according to claim 1, further comprising a reset circuit that sends a reset signal to a reset terminal of the circuit.

0010

[Function] With the above configuration, even if the signal generation circuit 7 malfunctions due to extremely large external noise and becomes continuously energized, the thermal fuse is prevented from operating, and a reset signal is sent to the signal generation circuit 7. By sending all operations back to their initial state and minimizing damage, we provide a solenoid drive circuit that can be reused as is, whereas previously it could only be reused without replacing parts. It is something.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Examples of the present invention will be described below with reference to the drawings.

In FIG. 1, 10 is an AC power supply, 11 is a DC power supply that rectifies the AC power supply 10 to obtain a DC output, 12 is a solenoid, 13 is a thermal fuse that operates when the temperature of the solenoid 12 rises abnormally, and 14 is a thermal fuse. a diode bridge for converting the voltage applied to the solenoid 12 into direct current;
15 is a switching element that drives the solenoid 12;
6 is a signal generation circuit that outputs a signal for controlling the switching element 6; 17 is a monostable multivibrator circuit;
8 is an AND circuit that outputs an ON signal only when the outputs of the signal generation circuit 16 and the monostable multivibrator circuit 17 are both ON signals, and 19 is a transistor.

Next, the operation of the circuit shown in FIG. 1 will be explained. A DC voltage is generated by a DC power supply 11 by rectifying the AC power supply 10 .

In normal operation, as shown in FIG. 3, when the signal generation circuit 16 generates a signal that turns on the solenoid 12, the output of the monostable multivibrator circuit 17 also becomes an on signal, which turns on the transistor 19 through the AND circuit 18. , turns on the switching element 15 and turns on the solenoid 1.
Drive 2.

Since the ON signal from the signal generating circuit 16 becomes an OFF signal in about 1 second, even if a large current is passed through the solenoid 12, the solenoid 12 generates little heat and generates a large force.

If the signal generation circuit 1 as shown in FIG.
6, if an abnormality occurs and the ON signal is continuously generated due to malfunction, the output of the monostable multivibrator circuit 17 will switch from the ON signal to the OFF signal during the time when the thermal fuse 13 does not operate, and the output of the AND circuit 18 will be The signal becomes an off signal, turns off the transistor 19, turns off the switching element 15, and stops energizing the solenoid 12.

Next, referring to FIG. 2, 20 indicates a signal generation circuit 16 and a monostable multivibrator circuit 17.
This is a reset circuit that supplies a reset signal to the signal generation circuit 16 depending on the output state of the circuit, and the rest is the same as in FIG.

Next, the operation of the circuit shown in FIG. 2 will be explained. The normal operation is the same as in Figure 1, and if signal generation circuit 1
If an abnormality occurs in 6 and the ON signal is continuously generated due to malfunction, the output of the monostable multivibrator circuit 17 switches from the ON signal to the OFF signal as shown in FIG. 4, similar to the circuit in FIG. The output of the AND circuit 18 becomes an off signal, which turns off the transistor 19, turns off the switching element 15, and stops energizing the solenoid 12.

At the same time, the reset circuit 20 outputs a reset signal to the signal generating circuit in response to the fact that the output of the signal generating circuit 16 is an on signal when the output of the monostable multivibrator circuit 17 is switched from an on signal to an off signal. 16, the malfunction of the signal generating circuit 16 is recovered.

[0020]

As is clear from the above description, the present invention prevents the signal generation circuit from malfunctioning due to extremely large external noise and becomes continuously energized, which causes the temperature fuse to operate. By sending a reset signal to the circuit, all operations are returned to their initial state and damage is minimized, making it possible to reuse items that could previously only be reused without replacing parts. This has a great effect on reliability and economy.

[Brief explanation of drawings]

FIG. 1: Circuit diagram of a first embodiment of the present invention.

FIG. 2 is a circuit diagram of a second embodiment of the present invention.

[Fig. 3] Time chart of the output of each circuit during normal operation according to the embodiment of the present invention

[Fig. 4] Time chart of output of each circuit during abnormality according to the embodiment of the present invention

[Figure 5] Circuit diagram of conventional example

[Explanation of symbols]

12 Solenoid 15 Switching element 16 Signal generation circuit 17 Monostable multivibrator circuit 20 Reset circuit

Claims (2)

[Claims] 1. A solenoid, a switching element for energizing the solenoid, a signal generating circuit for controlling the switching element and generating an on signal for turning on the solenoid, and the on signal for the signal generating circuit. a monostable multivibrator circuit that starts operation by, outputs an on signal for turning on the solenoid for a predetermined period longer than the on signal of the signal generating circuit, and then outputs an off signal for turning off the solenoid; A solenoid drive circuit comprising: a solenoid drive circuit configured such that the solenoid is turned on only when outputs of the signal generation circuit and the monostable multivibrator circuit are both on signals. 2. Resetting the signal generating circuit when the output of the monostable multivibrator circuit switches from the on signal to the off signal and when the output of the signal generating circuit is outputting the on signal. 2. The solenoid drive circuit according to claim 1, further comprising a reset circuit for sending a reset signal to the terminal.