JP7341108B2 - heating cooker - Google Patents

Description

The present invention relates to a configuration and means for detecting contact abnormality of a relay connected to a heater of a cooking device.

In heating cookers, relays are used to turn on the heater at arbitrary timings, and ON/OFF control is performed by the relay drive circuit, but the relay contacts can melt or weld, and if they are welded, the heater There is a risk of fire as the gas is constantly conductive and heated.

Patent Document 1 has a main relay for supplying power to the heater, a heater relay for turning the heater on and off, and a temperature detection section for detecting the temperature inside the cooking chamber, and when heating is started, only the main relay is turned on. A method is disclosed in which, when the temperature inside the cooking chamber is detected after a predetermined period of time has elapsed, if the temperature rises above a certain level, it is determined that the heater relay is welded and an abnormality is reported. ,

Patent Document 2, one terminal of two relays connected to both ends of a heater has a contact abnormality detection circuit, and has a current detection circuit that detects a current flowing through the heater, and has a contact abnormality detection circuit and a current detection circuit. A method is described in which an abnormality in one or both relays is detected from the consistency of the output of the relay.

JP2009-258049 JP 8-75176

In the heating cooker described in Patent Document 1, if the heater relay is normal, the heater will not conduct just by turning on the main relay, so heating will not occur until a predetermined period of time has passed after turning on the main relay, and cooking will take longer. It takes. The heating cooker described in Patent Document 2 has a current detection circuit for detecting the current flowing through the heater, and there is a problem in that the detection is costly.

The present invention has been made to solve the above-mentioned problems, and one aspect thereof includes a heating means for heating an object to be heated, a main relay connected to a front stage of the commercial power supply side of the heating means, and A relay operation abnormality detection signal is sent from a heater relay connected to the latter stage of the commercial power supply side of the heating means, and a relay operation abnormality detection circuit branched from between the heating means and the main relay and between the heating means and the heater relay. relay operation abnormality detection signal detection means for receiving the relay operation abnormality detection signal, and relay drive signal output means for outputting a relay drive signal that controls the operation of the main relay and the heater relay, the relay operation abnormality detection signal detection means, The pattern of the relay operation abnormality detection signal based on the operating state of the main relay and the heater relay is compared with the pattern of the relay operation abnormality detection signal estimated from the relay drive signal. A heating cooker that detects relay malfunctions.
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According to the present invention, it is possible to provide a cooking device that detects relay abnormalities in a short time and at low cost.

FIG. 1 is a circuit diagram showing a circuit configuration according to a first embodiment of the present invention. FIG. 3 is a diagram showing a power synchronization signal according to the first embodiment of the present invention. FIG. 3 is a diagram showing a relay operation abnormality detection signal according to the first embodiment of the present invention. 5 is a flowchart for detecting relay operation abnormality according to the first embodiment of the present invention. FIG. 6 is a diagram showing a normal relay operation abnormality detection signal pattern when the main relay and heater relay are turned off. FIG. 6 is a diagram showing a relay operation abnormality detection signal pattern when the main relay is not in an open state. FIG. 7 is a diagram showing a relay operation abnormality detection signal pattern when the main relay is not in a short-circuited state. FIG. 7 is a diagram showing a relay operation abnormality detection signal pattern when the main relay is normal and the heater relay is abnormal. FIG. 2 is a circuit diagram showing a circuit configuration according to a second embodiment of the present invention. FIG. 7 is a diagram showing a relay operation abnormality detection signal pattern when the main relay and heater relay are normal. FIG. 7 is a diagram showing a relay operation abnormality detection signal pattern when the main relay is normal and the heater relay is abnormal. FIG. 2 is a circuit diagram showing a circuit configuration according to a second embodiment of the present invention. It is a flowchart for detecting abnormality in relay operation according to a second embodiment of the present invention.

Embodiment 1 of the present invention will be described below with reference to the drawings and the like. The following description shows specific examples of the content of the present invention, and the present invention is not limited to these descriptions. Various changes and modifications can be made by those skilled in the art within the scope of the technical idea disclosed in this specification, and we have originally planned to combine the configurations of the following embodiments as appropriate. Further, in all the figures for explaining the present invention, parts having the same functions are given the same reference numerals, and repeated explanation thereof may be omitted.

FIG. 1 shows the form of a heating cooker for implementing the present invention. A heater 3 for heating an object to be heated, a main relay 2 and its driving circuit connected in series at the front stage of the commercial power supply 1 and both ends of the heater, and a heater relay 4 and its driving circuit connected in series at the rear stage. circuit, a relay operation abnormality detection circuit 5 connected between the main relay 2 and the heater 3 and between the heater 3 and the heater relay 4, a rectifier circuit 8 for rectifying the commercial power supply 1, and a rectifier circuit 8 connected to the rectifier circuit 8. It includes a power synchronization signal generation circuit 6 and a control section 70 that detects each signal and controls each relay. The control unit 70 includes a relay operation abnormality detection signal detection means 71 that detects a relay operation abnormality signal, a relay drive signal output means 72 that outputs relay drive signals for the main relay 2 and the heater relay 4, and detects the power synchronization signal. It has a power supply synchronization signal detection means 73 for detecting a power synchronization signal.

The power synchronization signal obtained from the power synchronization signal generation circuit 6 will be explained using FIG. The power supply synchronization signal generation circuit 6 is connected to the rectified commercial power supply 1 voltage after rectifying the commercial power supply 1, and includes a voltage dividing resistor, a filter circuit for noise reduction, a pull-up resistor, and a transistor for signal switching. configured. Since the rectifier circuit 8 is connected after the main relay 2, the input voltage changes depending on the operating state of the main relay 2.

When the main relay 2 is off (open state), the positive phase circuit is cut off by the main relay 2, so that only the negative phase voltage of the commercial power supply 1 is applied to the rectifier circuit 8. When the rectified commercial power supply 1 voltage is 0V, the transistor does not operate and is cut off, so a pulled-up signal (High) is input to the power supply synchronization signal detection means 73. When the rectified commercial power supply 1 voltage is higher than 0V (strictly speaking, when it is higher than the forward voltage Vf of the diode), the transistor operates and the pull-up resistor and GND are connected, so the power supply synchronization signal detection means 73 receives 0V. (Low) is input.

When the main relay 2 is on (short-circuited), the positive phase side is also conductive, so both positive phase and negative phase voltages are applied to the rectifier circuit 8. Since the operating conditions of the transistor do not change, a signal that becomes High when the rectified commercial power supply 1 voltage is around 0V (strictly speaking, when it is less than the Vf of the diode) is input to the power supply synchronization signal detection means 73.

FIG. 3 illustrates a relay operation abnormality detection signal obtained from the relay operation abnormality detection circuit 5 according to the operating states of the main relay 2 and the heater relay 4. The relay operation abnormality detection circuit 5 branches between the main relay 2 and the heater 3 and between the heater 3 and the heater relay 4, and includes a backflow prevention diode, a voltage dividing resistor, a filter circuit for noise reduction, and a pull-up resistor. , consists of transistors for signal switching.

When the main relay 2 and heater relay 4 are off (open state), they are cut off from the commercial power supply 1, so the voltage applied to the relay operation abnormality detection circuit 5 becomes 0V, and the transistor does not operate, so the relay operation abnormality detection signal A pulled-up signal (High) is input to the detection means 71.

When main relay 2 is on (short circuit state) and heater relay 4 is off (open state), commercial power 1 is applied only from the terminal connected between main relay 2 and heater 4, but heater relay 4 is cut off in the OFF state, so only the positive phase of the commercial power supply 1 is applied to the relay operation abnormality detection circuit 5. Since the circuit after application has the same configuration as the power synchronization signal circuit 6, the relay operation abnormality detection signal obtained at this time becomes Low when the commercial power supply 1 voltage is in the positive phase and High when it is in the negative phase. I get a signal.

When the main relay 2 is off and the heater relay 4 is on , the commercial power supply 1 and the relay operation abnormality detection circuit 5 are disconnected by the main relay 2, so that the main relay 2 is not connected between the heater 3 and the heater relay 4. The commercial power source 1 is applied only from the terminal, and only the negative phase of the commercial power source 1 is applied to the relay operation abnormality detection circuit 5. When the main relay 2 is off and the heater relay 4 is on, the relay operation abnormality detection circuit 5 has the same configuration as the power synchronization signal circuit 6, so the relay operation abnormality detection signal obtained at this time is based on the voltage of the commercial power supply 1 . A signal that is low when the phase is negative and high when the phase is positive is obtained.

When the main relay 2 and heater relay 4 are on, the main relay 2, heater 3, and heater relay 4 are connected to the commercial power supply 1, so both positive and negative phase voltages are applied to the relay operation abnormality detection circuit 5. be done. In this case as well, similarly to the power synchronization signal circuit, a relay operation abnormality detection signal that becomes High when the commercial power supply 1 is around 0V is obtained. Next, an example of operation for detecting an abnormality in the main relay will be described using FIGS. 4 and 5. FIG. 4 is a flowchart from outputting a control signal to turn off main relay 2 and heater relay 4 to detecting malfunction of main relay 2 or heater relay 4. Figures 5(a)-(d) illustrate the relay operation abnormality detection signal pattern and power synchronization signal pattern obtained when the control signal is output, depending on the operating status of the main relay 2 and heater relay 4. It is something.

First, the control unit 70 outputs a signal to turn off the main relay and the heater relay from the relay drive signal output means 72 (S101). Thereafter, the moment when the power synchronization signal rises from Low to High is detected (S102), and a relay operation abnormality detection signal is obtained after a certain period of time (S103). This is repeated a plurality of times (eight times in the first embodiment) and held as a relay operation abnormality detection signal pattern (S104). The held relay operation abnormality detection signal pattern is one of the relay operation abnormality detection signal patterns stored in the relay operation abnormality detection signal pattern storage means 74, which is a relay operation abnormality detection pattern with a combination of main relay off and heater relay off. HHHHHHHH” (S105). If the main relay is normal, as shown in FIG. 5(a), the acquired relay operation abnormality detection signal pattern will also be "HHHHHHHHH", which matches the stored relay operation abnormality detection signal pattern. If the main relay is not in an open state, that is, in a welded state and is malfunctioning, the acquired relay operation abnormality detection signal pattern will be "HLHLHLHL" or "LHLHLHLH" as shown in Figure 5(b). Since the pattern does not match the stored pattern, a malfunction in the welding state can be detected (S106).

If normal operation of the main relay is confirmed, a signal to turn on the main relay is output from the relay drive signal output means 72 (S107). After that, similarly to the relay operation abnormality determination method when the main relay is off, the moment when the power synchronization signal rises from Low to High is detected (S108), and after a certain period of time, a relay operation abnormality detection signal is obtained (S109). This is repeated a plurality of times (eight times in the first embodiment) and held as a relay operation abnormality detection signal pattern (S110). The held relay operation abnormality detection signal pattern is one of the relay operation abnormality detection signal patterns stored in the relay operation abnormality detection signal pattern storage means 74, which is a relay operation abnormality detection pattern with a combination of main relay on and heater relay off. HLHLHLHL" or "LHLHLHLH" (S111).

If the main relay is normal, the acquired relay operation abnormality detection signal pattern becomes "HLHLHLHL" or "LHLHLHLH" as shown in FIG. 5(a), which matches the stored relay operation abnormality detection signal pattern. If the main relay is not in a short-circuit state, that is, in a fused state and is malfunctioning, the acquired relay operation abnormality detection signal pattern becomes "HHHHHHHH" and is stored as shown in Figure 5(c). Since it does not match the pattern, malfunction of the main relay in the blown state can be detected (S112). In addition, if the heater relay is in a welded state and malfunctions, the acquired relay operation abnormality detection signal pattern will be "LLLLLLLL" as shown in Figure 5(d), which does not match the stored pattern. Malfunction of the welded state of the heater relay can be detected (S113).

Next, an example of operation for detecting a melting abnormality in the heater relay 4 will be described using FIG. 4 and FIGS. 6 and 7. FIG. 6 shows a flowchart from outputting a control signal that turns on both the main relay 2 and the heater relay 4 to detecting an abnormality (melt-out) in the heater relay 4. FIG. 7 shows the patterns of the relay operation abnormality detection signal and the power synchronization signal obtained when the control signal is output, according to the operating states of the main relay 2 and heater relay 4.

Here, it is assumed that the main relay is operating normally. First, the control unit 70 outputs a signal to turn on the main relay and the heater relay from the relay drive signal output means 72 (S201). Thereafter, the moment when the power synchronization signal rises from Low to High is detected (S202), and a relay operation abnormality detection signal is obtained after a certain period of time (S203). This is repeated a plurality of times (eight times in the first embodiment) and held as a relay operation abnormality detection signal pattern (S204). The held relay operation abnormality detection signal pattern is one of the relay operation abnormality detection signal patterns stored in the relay operation abnormality detection signal pattern storage means 74, which is a relay operation abnormality detection pattern for a combination of main relay ON and heater relay ON. LLLLLLLL” (S205).

If the heater relay is normal, the acquired relay operation abnormality detection signal pattern becomes "LLLLLLLL" as shown in FIG. 7(a), which matches the stored relay operation abnormality detection signal pattern. If the heater relay is fused and malfunctioning, the acquired relay operation abnormality detection signal pattern will be "HLHLHLHL" or "LHLHLHLHLH" as shown in Figure 7(d), which will not match the stored pattern. Therefore, malfunction of the heater relay in the blown state can be detected (S206).

By determining the abnormality of the relay as described above, malfunction of the main relay can be detected in a short time, and malfunction of the heater relay can be detected while performing a heating operation.

Example 2 of the present invention will be described using FIGS. 8 and 9. FIG. 8 shows a mode in which the heater 2 and the heater relay 4 are connected in parallel, unlike the first embodiment. The first heater 3a and the second heater 3b are branched in parallel from the front stage of the main relay 2 when viewed from the commercial power supply 1, and the first heater relay 4a and the second heater relay 4b are connected from the heaters 3a and 3b. They are each connected in series. A plurality of relay drive signal output means for outputting drive signals for heater relays are connected in parallel, and a relay operation abnormality detection circuit is provided between each heater and its heater relay.

FIG. 9 shows a flowchart for detecting malfunctions of the main relay 2 and heater relay 4 when the circuit configuration as shown in FIG. 8 is adopted. As in Example 1, a relay operation abnormality signal pattern is acquired (S302) with off signals output for all relays (S301), and if the acquired pattern is other than "HHHHHHHHHH", main relay 2 is welded. A malfunction in the state can be detected (S304). Next, the ON signal of the main relay 2 is outputted (S305), the relay operation abnormality signal pattern is acquired (S306), and if the acquired pattern is "HHHHHHHHH", the malfunction of the main relay is blown (S309), If "LLLLLLLL", it is possible to detect a malfunction in the welded state of the first heater relay 4a or the second heater relay 4b (S308).

Next, an ON signal for the first heater relay 4a is output (S310), a relay operation abnormality signal pattern is acquired (S311), and if the acquired pattern is "HLHLHLHL" or "LHLHLHLH", the first heater relay It is possible to detect a malfunction in the fused state of 4a (S313). Next, a signal to turn off the first heater relay 4a is output (S314), a relay operation abnormality signal pattern is acquired (S315), and if the acquired pattern is "LLLLLLLL", the welding state of the first heater relay 4a is determined. (S317). If a similar method is used, malfunction of the second heater relay 4b, such as welding or fusing, can be detected.

1: Commercial power supply 1
2: Main relay 3: Heater 3a: First heater 3b: Second heater 4: Heater relay 4a: First heater relay 4b: Second heater relay 5: Relay operation abnormality detection circuit 6: Power synchronization signal generation Circuit 8: Rectifier circuit 70: Control section 71: Relay operation abnormality detection signal detection means 72: Relay drive signal output means 72
73: Power supply synchronization signal detection means

Claims (1)

a heating means for heating an object to be heated;
a main relay connected to the front stage of the commercial power supply side of the heating means;
a heater relay connected to a later stage on the commercial power supply side of the heating means;
Relay operation abnormality detection signal detection means that receives a relay operation abnormality detection signal from a relay operation abnormality detection circuit branched from between the heating means and the main relay and between the heating means and the heater relay;
Relay drive signal output means for outputting a relay drive signal for controlling operations of the main relay and the heater relay;
A power synchronization signal is generated based on a rectified commercial power supply voltage after rectifying the commercial power supply received from a rectifier circuit branched from between the heating means and the main relay and between the heater relay and the commercial power supply. Equipped with a power synchronization signal generation circuit,
The power synchronization signal generation circuit receives the rectified commercial power supply voltage only when the voltage of the commercial power supply is in the negative phase when the main relay is off, and inputs the rectified commercial power supply voltage only when the voltage of the commercial power supply is in the negative phase when the main relay is on. The rectified commercial power supply voltage is input when the voltage is in both positive phase and negative phase,
The power synchronization signal becomes Low when the rectified commercial power supply voltage is equal to or higher than a predetermined value, and becomes High when the rectified commercial power supply voltage is less than a predetermined value,
The relay operation abnormality detection signal detecting means detects the relay operation abnormality detection signal a plurality of times after a predetermined period of time has elapsed from the moment the power supply synchronization signal rises from Low to High, and detects the relay operation abnormality detection signal pattern. The pattern of the relay operation abnormality detection signal obtained when the main relay and the heater relay are turned off by the relay drive signal is the relay operation that is estimated when the main relay and the heater relay are turned off. A heating cooker that detects malfunction of the main relay when the pattern does not match the pattern of the abnormality detection signal.

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