JPH04186025A - Heater driving device of electric heater - Google Patents

Abstract

PURPOSE:To perform power regulation through periodical relay on-off operation using a miniature inexpensive relay contact by successively changing the driving phase of the one relay of the two relays each having relay contacts connected to opposite ends of a heater. CONSTITUTION:With a start switch depressed, a second relay 7 is turned on, and provided that an output of a driving signal generation means 9 is of an on signal and it is required to drive a first relay 6, a contact 61 of the first relay 6 is turned on in synchronism with an output signal from driving phase determination means 12. Then, when the output of the driving signal generation means 9 is changed to an off state, and off driving is required, the contact 61 of the first relay 61 is turned off in synchronism with the output from the driving phase determination means 12. Herein, the driving of the relay 6 is achieved by alternately changing opening/closing polarity and successively changing driving phase. With a heating interruption key depressed the relay contact 61 is turned off in synchronism with the output signal from the driving phase determination means 12, and thereafter a second relay 7 is turned off.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a heater drive device for an electric heater that drives a heater by opening and closing a relay.

2. Description of the Related Art In recent years, heater drive devices for electric heaters such as electric heating heaters are required to have a longer service life by preventing welding of the contacts. There is a need to ensure safety.

Conventionally, a heater drive device for this type of electric heater, for example, an electric shoe heater, has generally had a configuration as shown in FIG. 13. The configuration will be explained below.

As shown in the figure, the heater 1 has relay contacts 2 on both ends.
3 was connected, and in response to a signal from the drive signal generating means 4, the relay contact 2.3 was turned on and off by the contact opening/closing means 6.

This is due to the following reason. In recent years, the spread of electrical equipment has been remarkable, and the number of so-called all-electric homes, where all of the heat in the home is powered by electricity, is increasing. Further, an earth leakage breaker is generally used as a safety device for commercial power supply circuits. However, if one of the heaters in the heater has poor insulation and cannot be disconnected, the earth leakage breaker will trip and cut off all power, rendering other equipment unusable. Become.

In contrast, with the above configuration, even if one of the multiple heaters has poor insulation, the heater with the defective insulation can be removed from the power supply circuit by turning off the relay contacts at both ends of the heater. This is because since it can be separated, cooking can be performed using another heater, and of course, other equipment can also be used.

Problems to be Solved by the Invention In such conventional heater drive devices for electric heaters, relays with large contact points have to be used as devices become more powerful, resulting in high power consumption and short time intervals. There is a problem in that it is difficult to perform power adjustment by periodically turning on and off (about 10-odd seconds to one minute) because there is a limit due to the lifespan of the relay contacts 2.3. The operating time and return time of the tabs and relay contacts 2 and 3 are subject to individual variations such as the number of windings in the relay coil and the strength of the spring.
Because relay power supply voltage fluctuations, coil resistance temperature changes, and changes over time can vary depending on many factors, a large amount of variation must be expected, and as a result, the guaranteed number of opening/closing operations under adverse conditions becomes significantly smaller.

In addition, increasing the power of equipment, especially 200 p/l/l as a power source,
) During use, the relay contacts 2 and 3 are subject to severe wear and tear, resulting in a significantly shortened lifespan.

Furthermore, when the life of relay contacts 2 and 3 finally ends,
Many of them cause contact welding and become continuously energized, so
There were also problems in that the amount of heating could not be adjusted or that it lacked safety.

The present invention solves the above-mentioned problems by periodically turning on the relay using a small and inexpensive relay contact.

The second purpose is to extend the life of the electrically applied relay, which can adjust the power by turning it off. The third objective is to extend the usable period of electric heaters, and the fourth objective is to increase the safety of electric heaters.
The purpose is to A fifth purpose is to notify the user of the welding of the contacts in order to ensure safety when the contacts of the relay are welded.

Means for Solving the Problems In order to achieve the above-mentioned first object, the present invention comprises relay contacts connected to both ends of a heater, and a drive circuit for driving the relay having these relay contacts. includes a drive signal generating means for instructing opening and closing of the relay, a power synchronization signal generating means for generating a signal synchronized with zero volts of the AC power supply, a drive position determining means for determining the drive phase of the relay, and the drive phase. contact opening/closing means for opening and closing the relay contacts in response to an output signal from the determining means;
The first means of solving the problem is to sequentially change the two drive phases.

Further, in order to achieve the second objective, in addition to the first problem-solving means, the drive circuit is equipped with a timer or counter, and the drive circuit is equipped with a timer or a counter, so that each time a predetermined time elapses or the relay is opened and closed a predetermined number of times, The second problem-solving means is to alternate between the relay that controls the drive phase and the other relay among the two relays.

In order to achieve the third object, in addition to the first or second problem solving means, the drive circuit includes contact signal generating means for generating a signal according to the open/closed state of the relay contact;
contact welding detection means for inputting the contact signal from the contact signal generation means and the output of the contact opening/closing means and detecting welding of the relay contacts based on a mismatch between the two, wherein the contact welding detection means detects welding of the contacts. In this case, the third means of solving the problem is to sequentially change the phase of the relay that does not cause contact welding to open and close.

In order to achieve the fourth object, in addition to the first or second problem-solving means, the drive circuit includes a contact signal generating means for generating a signal according to the open/closed state of the relay contact, and a contact signal generating means for generating a signal according to the open/closed state of the relay contact. contact welding detection means for inputting the contact signal from the generation means and the output of the contact opening/closing means and detecting welding of the relay contacts based on a mismatch between the two, and when the contact welding detection means detects welding of the contacts, The fourth means of solving the problem is to turn off both relays.

Furthermore, in order to achieve the fifth object, in addition to the third or fourth problem-solving means, the driving means is provided with a notification means, and when the contact welding detection means detects welding of the relay contact, the driving means is provided with a notification means. The sixth means for solving the problem is to notify the user of contact welding by means of means.

The present invention is based on the above-mentioned first means for solving the problem, and the relay that controls the current flowing through the heater is configured such that the on/off phase of the contacts is sequentially changed, so that the arc discharge at the relay contacts is reduced to a minimum value. Since the values are taken periodically from to the maximum value, individual variations in contact life can be suppressed. As a result, the number of guaranteed opening and closing times increases dramatically.

Furthermore, according to the second problem-solving means, the relay for power adjustment is replaced at predetermined intervals, and the wear and tear on the relay contacts due to periodic ON/OFF can be shared between the two relays.

Furthermore, according to the third problem-solving means, when contact welding occurs in one of the two relays, the remaining one relay can be used to adjust the heating amount and control on/off.

Further, according to the fourth problem-solving means, further heating is prohibited at the time when one of the two relays causes contact welding.

Furthermore, according to the sixth problem solving means, if one of the two relays causes contact welding, this can be notified to the user.

EXAMPLE Hereinafter, an example of the first problem-solving means of the present invention will be described with reference to FIG. Note that components having the same configuration as those of the conventional example are given the same reference numerals, and description thereof will be omitted.

As shown in the figure, a relay contact 61 of a first relay 6 and a relay contact 71 of a second relay 7 are connected in series to both ends of the heater 1, respectively. The drive circuit 8 drives the first and second relays 6.7, and the drive circuit 8 includes a drive signal generating means 9 for instructing opening/closing of the first and second relays 6.7, and an AC power source 1o. power supply synchronization signal generation means 11 that generates a signal synchronized with zero volts of It is provided with a contact opening/closing means 13 which opens and closes the relay contacts 81.71 in response to a signal. In addition, 14 is a full wave rectifier, 15
16 is a photocoupler, and 16 is a power source for the drive circuit 8. In this embodiment, drive signal generating means 9. The drive phase determining means 12 and the contact opening/closing means 13 are constituted by a one-chip microcomputer. Although not shown here, the drive signal generating means 9 is connected to a key switch provided on the main body operation section, and the heating amount is set by the key switch within a predetermined period of time. , a signal is output to turn on the first and second relays 6.7 for an arbitrary time and turn them off for the remaining time.

In another heating mode, when the temperature of the object to be heated is higher than a predetermined temperature based on the output of the temperature detection means that detects the temperature of the object to be heated, it is turned off and When it becomes low, 8 on signals are generated. ``Next, the operation of the above configuration will be explained with reference to FIG. 2.

First, initial settings are made in step 101, and in step 102, a start switch (not shown here) provided on the heater body is pressed.

When the start switch is pressed, the second
First, turn on relay 7. Next, step 10
4, the output of the drive signal generation means 9 is checked, and if it is an ON signal and it is necessary to drive the first relay 6, the process proceeds to step 105, where the output signal of the drive signal generation means 9 is synchronized with the output signal of the drive phase determination means 12, and the first relay 6 is output. Turn on the relay contact 61 of the first relay 6.

Then, in step 106, it is checked whether a heating stop key (not shown) has been pressed, and if it has not been pressed, the process returns to step 104.

Then, in step 107, when the output of the drive signal generating means 9 is turned off and off drive is required, step 10
8 in synchronization with the output signal of the drive phase determining means 12.
The relay contact 61 of the relay 6 is turned off. The on operation at step 105 and the off operation at step 108 will be explained later. On the other hand, if it is detected that the heating stop key is pressed in step 1oθ, the next step 10
After the relay contact 61 of the first relay 6 is turned off in step 9 in synchronization with the output signal of the drive phase determining means 12, the second relay 7 is turned off in step 110.

Next, the on and off operations of the first relay 6 will be explained. Figure 3 shows the first output when the power frequency is 60Hz.
2 is a flowchart of the operation when turning on the relay 6 in synchronization with the output signal of the drive phase determining means 12. In step 201, an output signal (hereinafter referred to as zero volt pulse (zvp)) of the power synchronization signal generating means 11 synchronized with zero volt of the AC power source 1o is waited for. Step 202
After counting up the ZvP counter built in the drive phase determining means 12 in step 203, it is checked whether the ZvP counter is an even number. If the ZvP counter is an odd number, the process returns to step 201 and waits for a zero port pulse again. The reason for waiting for the ZvP counter to become an even number is to alternately change the polarity of opening and closing the relay contacts to prevent transition of the contacts, which will be explained in detail later. ZvP
If the counter becomes an even number, the process proceeds to step 204, and the delay counter built in the drive phase determining means 12 is set to the set value N.
The loop of steps 205 and 206 is repeated until reaching .

When the delay counter reaches the set value N, Sten 7'20
Step 7, 208 clears the delay counter and increases the set value N by 1, and in step 211 the first relay 6
Press the signal to turn on. If the set value N becomes 8 or more, it is returned to 0 in step 210. In other words, after waiting for the set value N x 1m5ec from the zero volt pulse,
relay 6 is turned on, and this set value N is the first relay 6
Increases each time is turned on. FIG. 4 is a flowchart of the operation when turning off the first relay 6. Steps 301 to 311 correspond to steps 201 to 211 in FIG. 3, and their explanation will be omitted.

Next, a method of alternately changing the opening and closing polarity will be explained. In step 203 and step 303, only when the zvP counter is an even number, the subsequent first relay 6
Also, the zero volt pulse is applied to the alternating current as shown in the fifth garden in one cycle of the power supply 10,
This occurs twice as shown in FIG. 6(B). Therefore, the first
ZvP at step 312 each time relay 6 is turned off.
If the counter is counted up as shown in Fig. 6 (q), the open/close polarity can be changed alternately as a pair of on and off. The situation is shown in the timing chart and phase angle in Figure 6.By the way, if the above operation is done alone, the timing will return to the timing of (a) the first turn on after the fourth turn off (h) in Figure 6. , the symmetry between decapolarity and unipolarity is not high.

Therefore, in step 313, when the set value N becomes 8 or more, the ZvP counter is further incremented by 1.
) The fifth turn-on timing is used to maintain high symmetry between decapolarity and unipolarity. Power frequency is 5
In the case of oHz, set the delay in step 205.305 to 1.
．． It is the same except that it is set to 2m5eC.

Next, an embodiment of the second problem-solving means will be described with reference to FIG. 7. Note that the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted.

As shown in the figure, when a predetermined time has elapsed, a timer 18 provided in the drive circuit 17 controls a contact opening/closing means 19 based on its output, and the contact opening/closing means 19 controls the first and second contact opening/closing means 19 for controlling the drive phase. Relays 6.7 are replaced at predetermined intervals. In this embodiment, the timer 18 is also constituted by a one-chip microcomputer.

The operation of the above configuration will be explained along the flowchart of FIG.

After the initial setting in step 401, a check is made to start heating in step 402, and if heating has started, step 40
After clearing the timer 18 and resetting the timer flag in step 3, the second relay 7 is turned on in step 404. Step 405 is a routine for counting up the timer 17, in which a timer flag is set at predetermined intervals. Steps 406 to 412 are similar to the above embodiment, and if it is necessary to turn on the first relay 6, it is turned on in synchronization with the output signal from the drive phase determining means 12 in step 407, and if it is necessary to turn it off, it is turned on in step 407. In step 410, the output signal from the drive phase determining means 12 is turned off in synchronization with the output signal from the drive phase determining means 12, and in step 408, a check is made to see if the heating has stopped.If the heating is to be stopped, the output signal from the driving phase determining means 12 is turned off in step 411. After turning off the first relay 6 in synchronization with , the second relay 7 is turned off in step 412. In step 413, a timer flag set by the timer 18 at predetermined time intervals is checked to determine whether a predetermined time has elapsed. If the timer flag is set, the second relay 7 is also turned off in step 414, and the process proceeds to step 503.

Steps 603 to 614 are performed in step 403 except that the first relay 8 and second relay 7 are exchanged and controlled.
to step 414, the second relay 7 is turned on and off in synchronization with the output signal from the drive phase determining means 12 until the predetermined time elapses again, and when the predetermined time elapses, the process proceeds to step 403. return.

By repeating the above operation, the relay contacts 61 of the first relay 6 and the second relay 7 can be turned on and off by only one relay. γ1
The consumption of each is halved. Note that a counter is provided in place of the timer 18, and each time the first and second relays 6.7 are opened and closed a predetermined number of times, the first and second relays 6.
．． 7 may be alternated.

Next, an embodiment of the third problem-solving means will be described with reference to FIG. 9. Note that the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted.

As shown in the figure, the drive circuit 20 has two relay contacts 61
．． Contact signal generating means 21.22 generate signals corresponding to the respective open/close states of relay contacts 61. The contact welding detection means 24 and 25 detect the welding of the contact welding.
4.25 controls the contact opening/closing means 23;
3 controls the power consumption of the heater 1 by controlling the drive phase of the relay that does not cause contact welding and turning it on and off. In this embodiment, the contact signal generating means 2
1 and 22 are composed of a full-wave rectifier 2e and a food coupler 27, and the contact welding detection means 24 and 25 are also composed of a one-chip microcomputer.

The operation of the above configuration will be explained along the flowchart of FIG. 10.

Steps 401 to 414, Steps 503 to 514
The processing is similar to the embodiment of the second problem solving means described above, and after steps 410 and 510, the contact welding detection means 24.
a processing step 415 for checking the output of 25;
515 has been added. Regarding the processing in step 415, steps 403 to 410 and 41
3° 414, and while the second relay 7 is always on and the first relay 6 is turned on and off to control the power amount of the heater 1, step 41
If the relay contact e1 is welded despite the attempt to turn off the first relay 6 at 0, the contact welding detection means 24
Welding is detected in step 416, and the process proceeds to step 503. Then, they temporarily give up on controlling the power amount of the heater 1 by turning the first relay 6 on and off, and instead keep the first relay 6 always on and switch the second relay 6 on and off.
The power amount of the heater 1 is controlled using the relay 7 .

Thereafter, when a predetermined time has elapsed according to the timer 18, the processing in steps 513 and 514 is performed, and then step 403
Return to and turn on the first relay 6 again.

Attempt to control the amount of power of heater 1 by turning it off.

This is to test this, since when the relay contacts 61 or 71 wear out, a slight welding or catching called soft stick occurs temporarily, but this soft stick often returns to normal after a slight trigger. In step 516, similar processing is performed on the second relay 7.

With the above-described configuration and operation, even if one of the first and second relays 6.7 causes contact welding, this is detected and the other normal relay is used to control the power amount of the heater 1. I can do it.

Next, an example of the fourth problem solving means will be described. The configuration is the same as the embodiment of the third problem solving means described above.

FIG. 11 is a flowchart showing the operation of this embodiment.
If it is determined in step 416 that the contacts of the first relay 6 have welded, the process moves to step 611 to turn off the second relay 7, and then sends an off signal to the first relay 6 as well, and proceeds to step 402. return. The processing in step 616 is the same except that the first relay 6 and the second relay 7 are reversed.

Processing other than when contact welding occurs is the same as in the above embodiment.

With the above-described configuration and operation, when contact welding occurs in one of the first and second relays 6.7, this is detected and both the first and second relays 6.7 are turned off, and the heating is performed. stop.

Next, an embodiment of the fifth problem solving means will be described with reference to FIG. 12. Note that the same components as those in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted.

As shown in the figure, the drive circuit 28 includes a notification means 29,
When either the relay contacts 61 or 71 are welded in response to the output from the contact welding detection means 24, 25, the notification means 29 drives the buzzer 30 and the light emitting diode 31 to notify the user of the welding of the contacts. In this embodiment, the notification means 29 is also realized by a one-chip microcomputer.

With the above-described configuration and operation, if one of the first and second relays 6.7 causes contact welding, this can be detected and immediately notified to the user.

Effects of the Invention As is clear from the above embodiments, according to the present invention, one of the two relays is opened and closed while sequentially changing the drive phase, so a small and inexpensive relay contact can be used. Periodic relay on.

It is possible to adjust the power by turning off the power, and if used in a pressure cooker, the cooking performance will be improved and it will be useful. Since the relay that controls the drive phase of the two relays is replaced, the life of the relay can be extended.

Furthermore, since contact welding is detected and the power is adjusted by the normal relay, the usable period of the electric heater can be extended to the maximum extent possible. Furthermore, since both relays are turned off immediately upon detection of contact welding, the safety of the electric heater can be improved. Furthermore, since contact welding is detected and the user is notified, safety can be further ensured.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a heater drive device of an electric heater according to an embodiment of the present invention, Fig. 2 is an operation flowchart of the heater drive device, and Fig. 3 is a relay by changing the drive phase of the heater drive device. FIG. 4 is a flowchart for turning off the relay by changing the drive phase of the heater drive device. FIG. 5 is a diagram showing the output of the power synchronization signal generating means of the heater drive device. FIG. A timing chart when the relay is turned on and off by changing the drive phase of the drive device, FIG. 7 is a block diagram of a heater drive device for an electric heater according to another embodiment of the present invention, and FIG. 8 is a diagram showing the same heater drive. An operation flowchart of the device, FIG. 9 is a block diagram of a heater drive device for an electric heater according to another embodiment of the present invention,
FIG. 1o is an operation flowchart of the same heater drive device, FIG. 11 is an operation flowchart of the heater drive device of an electric heater according to another embodiment of the present invention, and FIG. 12 is an operation flowchart of the heater drive device according to another embodiment of the present invention. Block diagram of the heater drive device, 1st
FIG. 3 is a block diagram of a heater drive device for a conventional electric heater. 1... Heater, 6... First relay,
7... Second relay, 8... Drive circuit, 9... Drive signal generating means, 10...
AC power supply, 11...Power synchronization signal generation means, 1
2... Drive phase determining means, 13... Contact opening/closing means, 61... Relay contact, 71...
...Relay contact. Name of agent: Patent attorney Akira Okaji and two others Figure 2 Figure 31 Stone 4 Figure 5 (Suzvrou 4 j-14L+l i
+t ttJ Figure 6 (^) (8) W% 8 Mouth 1 & 10 Figure 11

Claims (5)

[Claims] (1) Relay contacts connected to both ends of the heater,
It consists of a drive circuit that drives a relay having these relay contacts, and the drive circuit includes drive signal generation means for instructing opening and closing of the relay, and power supply synchronization signal generation means for generating a signal synchronized with zero volts of the AC power supply. , comprising drive phase determining means for determining the drive phase of the relay, and contact opening/closing means for opening and closing the relay contacts in response to an output signal from the drive phase determining means, and the drive circuit is one of the two relays. A heater drive device for an electric heater that sequentially changes one drive phase. (2) The drive circuit is equipped with a timer or counter, and switches between the relay that controls the two relay drive phases and the other relay every time a predetermined time elapses or every time the relay is opened and closed a predetermined number of times. The heater drive device for an electric heater according to claim 1, wherein the heater drive device is configured to (3) The drive circuit includes a contact signal generating means that generates a signal according to the open/close state of the relay contact, and inputs the contact signal from the contact signal generating means and the output of the contact opening/closing means, and detects a discrepancy between the two and generates a relay contact. contact welding detection means for detecting welding of the contacts, and when the contact welding detection means detects welding of the contacts, the relay that does not have contact welding is opened and closed by sequentially changing its phase. A heater drive device for an electric heater according to claim 1 or 2. (4) The drive circuit includes a contact signal generating means that generates a signal according to the open/close state of the relay contact, and inputs the contact signal from the contact signal generating means and the output of the contact opening/closing means. 3. The electric heater according to claim 1, further comprising contact welding detection means for detecting welding of the contacts, and when said contact welding detection means detects welding of the contacts, both of the two relays are turned off. heater drive device. (5) The drive circuit has a notification means, and when the contact welding detection means detects welding of the relay contact, the notification means notifies the user of the contact welding. Heater drive device for heater.