JPS6262013B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a relay control circuit that turns on and off the contacts of a relay, and is capable of preventing welding of the contacts of the relay, and is particularly suitable for use in room air conditioner dayers. This relates to control circuits.

In general, a room air conditioner is equipped with a temperature detector that detects the temperature in the room to be air-conditioned.For example, in the case of cooling operation, when the temperature in the room rises above a predetermined temperature, the refrigeration system is operated. As a result, when the indoor temperature drops, the refrigeration system stops operating. When the indoor temperature rises again, the cooling operation is restarted to lower the indoor temperature again. By the way, even if the refrigerant compressor used in a refrigeration system is restarted within a short time after its operation has been stopped, the pressure of the compressed refrigerant will normally exceed the starting force of the compressor, and the compression will continue. The machine cannot start. And the compressor is damaged. "The pressure of the refrigerant decreases after a certain amount of time. Therefore, in a room air conditioner, when the refrigeration system is operating, the indoor temperature drops, and after the refrigeration system is stopped, the indoor temperature decreases. Even if the indoor temperature suddenly rises and exceeds a predetermined temperature, the compressor does not restart immediately, but only after a predetermined period of time has elapsed. A device that temporarily prohibits the restart of a compressor is usually installed in the control circuit of a relay that turns on and off the current flowing to the compressor motor, and is a part of the conventional control circuit 4 (broadly speaking, the clock). 20, 2, 2' for signal creation,
3 and 3').

To explain the outline of the operation shown in Fig. 3 in relation to prohibition of restart, when the control signal f from the temperature sensor is 4
1, and as the room temperature drops, f becomes "L" and the compressor is turned off, then the room temperature suddenly rises and f immediately becomes "H", and the compressor does not turn on immediately, and as shown in Figure 2 or Only after time _T1 in FIG. 7 has elapsed does d become "H" and the compressor is restarted.

Conventionally, in relay control equipment that shapes the voltage waveform of the commercial power supply and uses it as a reference clock signal, the phase of the control output signal that turns the relay on and off is synchronized with the phase of the reference clock signal, so the relay is turned on and off. The off timing always coincides with a certain fixed phase of the voltage waveform of the commercial power supply.

This situation will be explained using the block diagram of a conventional relay control circuit shown in FIG. 1 as an example and the signal waveform diagram shown in FIG. 2. The voltage waveform a of the commercial power supply 1 is passed through a power supply circuit 20 consisting of a power transformer, etc., and then passed through a half-wave rectifier 2.
The rectified signal b rectified by is subjected to waveform shaping in a waveform shaping circuit 3 using the voltage g as a threshold level, and a reference clock signal c is obtained at the output of the waveform shaping circuit 3. Consider a case where this reference clock signal c is used as the reference clock signal of the control circuit 4, and the load 8 is timer-controlled using the control signal f supplied from, for example, a temperature sensor as a control input signal. time
As the control output signal d becomes level H at time t ₀ , the relay 7, which was turned on at time t ₁ after time T ₂ has elapsed, changes the time regardless of the reference clock signal c.
At _t2 , it is reset (turned off) by the control signal f.
Then, the control circuit 4 counts the reference clock signal c from time _t3 , and generates a high level H control output signal d at time _t5 after the set timer operation time _T1 . In this case, as shown in FIG. 2, the phase in which the control output signal d of the control circuit 4 reaches a high level H at time _t5 coincides with the rising edge of the reference clock signal c. When the output signal d becomes a high level H, the drive circuit 5 is driven by the control output signal d. If the time from when current flows through the coil 6 of the relay 7 until the contact of the relay 7 turns on is _T2 , the timing at which the contact of the relay 7 turns on at time _t6 is based on the voltage waveform a of the commercial power supply 1. It will always match the determined phase 12. In most cases, the control signal f is at a high level H at time _t4 . Therefore, the input currents e of the contacts of the relay 7 are in the same direction and the same phase 30, as shown in FIG.

Here, the current in phase 12 flowing through contact 7 in FIG. same direction).

Therefore, similar to the application of DC current explained above, whenever the contact 7 in Fig. 1 is turned on, the direction of the application current flowing through the contact 7 is as shown in Fig. 2 t ₁ even though alternating current is applied. Contact point 7 at point or t ₆ points
If the current e is always in the same direction, the transition phenomenon of the contact progresses, shortening the life of the contact and eventually causing an accident of contact welding.

Here, the transition phenomenon of contacts is the melting of metal due to the heat generation of a large current such as direct current when applied in the same direction to metal contacts such as relays, and the melting of metal due to the arc during cutting. This is a phenomenon in which ions transfer to the negative electrode side and accumulate, and as mentioned above, whenever the contact 7 is always on, the contact 7
If the phenomenon in which the direction of the current flowing through the contacts continues to repeat in the same direction, a large current is repeatedly applied to the contact 7 in the same direction, similar to direct current, and the transition phenomenon of the contacts progresses, resulting in contact welding. There were problems such as accidents.

An example of the control circuit 4 is shown in FIG. The control circuit 4 includes a differentiating circuit 42, a counter 43 consisting of a frequency dividing circuit, and an AND gate 45. A control signal f is input to a terminal 41, a reference clock signal c is input to a terminal 44, and a control output signal is input from a terminal 46. d is output. The falling edge of the control signal f supplied to the terminal 41 is differentiated by the differentiating circuit 42 at time t2 in FIG. ₂ , and the counter 43 is reset by the output signal of the differentiating circuit 42. That is, the control signal f is a reset signal for the control circuit 4. When the counter 43 is reset, the counter 43 starts counting the reference clock signal c supplied from the terminal ₄₄ at time _t2 in FIG. The output signal of the counter 43 generates a high level H signal. When the control signal f applied to the terminal 41 is at a high level H at time _t4 before time _t5 , the output signal of the counter 43 passes through the AND gate 45, and the control output signal d
It is output from the terminal 46 as . That is, a signal d synchronized with the reference clock signal c is output from the terminal 46.

FIG. 4 shows a specific configuration of the differential circuit. FIG. 5 shows voltage waveforms at each part. Differential circuit 42 includes capacitor 141 and resistor 14
2. Consisting of an inverter 143 and a terminal 144
A control signal f is supplied to the terminal 146, and a signal h is supplied to the terminal 146.
is output from. A constant DC voltage is supplied to the terminal 145. When the control signal f is applied to the control circuit 4, the terminal 144 receives the _control output signal d shown in _FIG . is differentiated, resulting in signals p ₁ and p ₂ shown in FIG. 5b. The signals p ₁ and p ₂ are then supplied to an inverter 143, and when the signal p ₂ exceeds the threshold voltage q of the inverter 143, the inverter 143 generates a signal h shown in FIG. 5c.

An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to change the direction of the current flowing through the contact 7 when closing the relay to the t ₁₁ and t ₁₆ portions of the waveform of the current e in FIG.
It is possible to alternately flip the parts like
By alternating the direction of the current flowing through the contact 7, the direction of the transition (movement) of the molten metal ions in the aforementioned transition phenomenon is changed, and the transition is reduced by preventing the ions from being biased toward one pole. An object of the present invention is to provide a relay control circuit that prevents contact deterioration and welding.

In order to achieve the above object, the present invention generates a first reference clock signal by rectifying the voltage of a commercial power supply in both waves and shaping the waveform, and divides the frequency of this first reference clock signal by 1/2. and generates a second reference clock signal. The control circuit is driven by this second reference clock signal. Each time the control signal is supplied to the control circuit, one pulse is added to the first reference clock signal, thereby inverting the phase of the second reference clock signal, and the control signal is input to the control circuit. The phase at which the control output signal attached to the polarity of the commercial power supply is turned on is alternately switched each time the switch is turned on.

FIG. 6 is a block diagram showing an embodiment of the relay control circuit according to the present invention, in which a full-wave rectifier circuit 2' is used as the rectifier circuit, and the waveform shaping circuit generates a pulse when the threshold voltage g is exceeded. A waveform shaping circuit 3' is used which outputs . In addition, the pulse addition circuit 13 and the frequency divider 1
6 is connected between the waveform shaping circuit 3' and the control circuit 4.

In addition, in the present invention shown in FIG. 6, including the conventional example shown in FIG. The pressure of the refrigerant does not drop until a certain amount of time has passed after the operation is stopped, and in order to avoid damage to the compressor due to immediate restart, the refrigerant pressure is Since there is no device that prohibits restarting for a certain period of time (approximately 3 minutes) even if f becomes "H" immediately again, the compressor will be damaged. Therefore, the control circuit 4 is required, and the circuits 20, 2, 2', 3, and 3' are also required to generate the clock signal.

Next, the operation of FIG. 6 will be explained using the signal waveform diagram of FIG. 7. Signal a from power supply 1 is sent to rectifier circuit 2'
The signal is full-wave rectified to become a rectified signal b', which is input to the waveform shaping circuit 3'. Threshold voltage g
When the voltage of the rectified signal b' becomes larger than the voltage of the rectified signal b', the waveform shaping circuit 3' generates a pulse signal c', and this pulse signal c' is used as the first reference clock signal. This reference clock signal c' is supplied to one terminal of the OR gate 15 of the pulse adding circuit 13. On the other hand, the control output signal d of the control circuit 4 is differentiated by the differentiating circuit 14 of the pulse adding circuit 13, and is supplied to the other terminal of the OR gate 15 as a signal h.

Here, the control circuit 4 in FIG. 6 has the same configuration as the control circuit 4 in FIG. 3 described above. Therefore, both the outputs of the signal h and the reference clock signal c' become the output signal i of the pulse adding circuit 13. This signal i is added to the frequency divider 16 (which operates on falling input) which is the reference signal circuit of the control circuit 4, and the frequency divider 1
The output j of 6 is used as the reference clock of this control circuit 4. As a result, every time the output signal d of the control circuit 4 falls, the phase of the fall of the output signal j of the frequency divider 16 is inverted with respect to the polarity of the commercial power supply. Therefore, at time _t10 , the control signal d becomes high level H, and after a delay of time _T2 , at time _t11 , the voltage phase of the AC voltage a of the commercial power supply 1 (7th If the phase (phase at the time point in FIG. 12) 12 is "positive", the control signal f becomes level L at time t ₁₂ regardless of the phase of the commercial power supply 1, and after turning off the relay 7, control starts at time t ₁₃ . Circuit 4 starts counting signal j and the set timer operation time
After T ₁ has elapsed, that is, after time t ₁₅ , the next time the relay 7 is turned on, the phase is “negative” phase 17 because the time t ₁₆ is when the time T ₂ required for the contacts of the relay 7 to close has elapsed. becomes. Moreover, the absolute values of the input currents at that time are the same. Therefore, each time the relay 7 is turned on and off by timer control, the phase of the input current flowing through the contacts alternates between positive and negative, and since the current values are the same, even if a transition occurs in the contacts, there will be no change in phase as in the conventional case. It is not integrated in the direction.

That is, in the present invention, the full-wave rectifier circuit 2' and the waveform shaping circuit 3' generate a reference clock signal c' with a period twice that of the commercial power supply 1, and this reference clock signal c'
The frequency of c′ is divided by 1/2 by a frequency divider 16 to generate a reference clock signal j having the same period as that of the commercial power supply 1,
This reference clock signal j is supplied to the control circuit 4. On the other hand, the output signal of the control circuit 4 is supplied to the pulse addition circuit 13, and is differentiated by the differentiation circuit 14 of the pulse addition circuit 13 to become a signal h. This signal h is added to the reference clock signal c' by an OR gate 15. Therefore, when the control circuit 4 generates the output signal d at time t ₁₂ , the signal h is generated, and from time t ₁₂
The signal h is added to the reference clock signal c' until _t13 . By inputting this added signal h to the frequency divider 16, the output signal j of the frequency divider 16 becomes the time
Inverted at t ₁₃ . The clock signal j changes every time the control output signal d becomes low level L, that is, the control signal f
Each time the signal becomes a low level L, its phase is reversed. Therefore, the reference clock signal j and the voltage waveform a of the commercial power supply 1 at the elapse of time _T1 are
The relative polarity of is reversed, and the polarity of the commercial power supply when the relay 7 is turned on after a further elapse of time _T2 is reversed every time. Therefore, the direction of the current flowing through the relay 7 is reversed each time the relay 7 is turned on, and welding of the contacts of the relay 7 is prevented.

Note that the current flowing through the relay coil does not rise rapidly due to the inductance of the coil, and may require _{several cycles} . The absolute phase (values of t ₁₁ and t ₁₆ ) has large variations due to variations in coil inductance (for example,
(The direction and absolute value of the current e at time t ₁₁ vary widely.) However, once the room air conditioner is decided, the coil is decided as well, and its inductance hardly changes over time, so once it is decided, the value of t ₁₁ is almost constant and its The value of the current e at time _t11 hardly changes each time.

Moreover, t ₁₆ and t ₁₁ are the same as p10l8~l19's ``Therefore~
Absolute values are equal. As explained in ``Even if there are variations in inductance, the phase of the input current flowing through the contact repeats positive and negative alternately, and the current value is the same, so even if a transition occurs in the contact, it will not be integrated in one direction.'' It will not be done.

As described above, according to the present invention, the direction of the current flowing through the contacts is reversed each time the relay is opened and closed, and the current value can be made equal and small.
It is possible to reduce transfer of relay contacts and prevent contact deterioration and welding.

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional relay control circuit.
Figure 2 is a signal waveform diagram of each part in Figure 1, Figure 3 is a block diagram of the control circuit, Figure 4 is a block diagram of the differential circuit, Figure 5 is a waveform diagram of each part, and Figure 6 is the invention of the present invention. FIG. 7 is a block diagram showing an embodiment of a relay control circuit according to the present invention, and FIG. 7 is a signal waveform diagram of each part of FIG. 2'... Rectifier circuit, 3'... Waveform shaping circuit, 4...
...Control circuit, 7...Relay, 13...Pulse addition circuit, 14...Differential circuit, 15...OR gate,
16... Frequency divider.

Claims (1)

[Scope of Claims] 1. A reference clock signal generation means for rectifying and shaping the voltage waveform of a commercial power source to generate a reference clock signal, and a reference clock signal is inputted from the reference clock signal generation means, and a reset signal is also inputted. and after the reset signal is input, count the reference clock signals, turn off the relay until a predetermined number of reference clock signals are counted, and after counting the reference clock signals by a predetermined number, In a relay control circuit comprising a control circuit that generates a control output signal to turn on the relay and controls the relay to turn on or off according to the control output signal, the reference clock generating means is configured to generate a voltage of the commercial power supply. By full-wave rectifying the waveform and shaping the waveform, a reference clock signal with a period half the period of the commercial power supply is generated, and a reference clock signal with a period of 1/2 is connected between the reference clock signal generation means and the control circuit. A frequency divider is connected between the frequency divider and the reference clock signal generation means, and when a reset signal is supplied to the control circuit,
A control output signal that turns the relay off is input in synchronization with the reset signal, and a pulse addition circuit is connected that adds one pulse signal to the reference clock signal each time a control output signal that turns the relay off is input. A relay control circuit characterized by: