JP6874505B2 - Combustion device - Google Patents

Description

The present invention relates to a combustion device, and more specifically, to a combustion device having a configuration in which a plurality of microcomputers are operated by using a plurality of power supply voltages.

In order to improve the reliability of the system, the hot water supply device is controlled by a microcomputer device that uses a plurality of microcomputers (hereinafter, also simply referred to as “microcomputers”) as a main microcomputer and a sub-microcomputer. It is described in Japanese Patent Application Laid-Open No. 1 (Patent Document 1). According to the microcomputer device described in Patent Document 1, it is described that an abnormality of a microcomputer is detected by monitoring a communication status when two-way control data is exchanged between the microcomputers.

JP-A-2002-318003

In the microcomputer device described in Patent Document 1, the power supply voltage of the main microcomputer and the sub-microcomputer is common. Therefore, when the power supply voltage is abnormal, it becomes difficult for both microcomputers to operate normally.

On the other hand, by arranging a plurality of power supply circuits and adopting a configuration in which some of the plurality of microcomputers (control circuits) operate with different power supply voltages, it is possible to improve the reliability of the system. ..

However, in the configuration in which a plurality of microcomputers are operated by a plurality of power supply voltages as described above, when only a part of the power supply voltages becomes abnormal, some microcomputers that operate in response to the power supply voltage are not normal. There is a risk of performing different control actions.

In particular, in a configuration in which a mechanism related to fuel combustion is controlled, such as a combustion device, some power supply voltages are abnormal so that control under abnormal power supply voltage as described above is not continuously executed. At some point, it is required to detect this appropriately.

The present invention has been made to solve such a problem, and an object of the present invention is a part of a power source in a combustion device having a configuration in which a plurality of microcomputers are operated by using a plurality of power supply voltages. It is to reliably detect that the voltage is abnormal.

In one aspect of the present invention, the combustion device is a combustion device in which a combustion mechanism is controlled by a plurality of microcomputers having a common operating power supply voltage value, and includes a plurality of power supply circuits and a power supply voltage abnormality detection unit. The plurality of microcomputers are a first microcomputer that operates by receiving a first power supply voltage generated by a first power supply circuit among the plurality of power supply circuits, and a second power supply circuit among the plurality of power supply circuits. Includes a second microcomputer that operates in response to a second power supply voltage generated by. The power supply voltage abnormality detector uses the ratio of the voltage that changes according to the change of the first power supply voltage to the second power supply voltage, and one of the first and second power supply voltages is abnormal. Is detected.

According to the above-mentioned combustion apparatus, since the first and second microcomputers are operated by the first and second power supply voltages by the separate power supply circuits, the reliability of the system is improved and the first and second power supply voltages are increased. The fact that only one of them is abnormal can be detected by monitoring the ratio of the first and second power supply voltages via a voltage that changes according to the first power supply voltage. As a result, it is possible to reliably detect that some of the power supply voltages are abnormal in the combustion device having a configuration in which a plurality of microcomputers are operated using a plurality of power supply voltages.

Preferably, the fuel system further comprises a voltage divider circuit. The voltage divider circuit divides the first power supply voltage by a predetermined voltage dividing ratio. When the voltage ratio of the output voltage of the voltage dividing circuit to the second power supply voltage deviates from the predetermined range including the reference value determined corresponding to the voltage dividing ratio, the power supply voltage abnormality detection unit sets one of the power supply voltages. Detect that it is abnormal.

With such a configuration, one of the first and second power supply voltages is used from the voltage ratio of the output voltage of the voltage divider circuit to the second power supply voltage using the reference value determined according to the voltage divider ratio of the voltage divider circuit. Can be detected as abnormal.

Also preferably, the fuel system further comprises a sensor that operates on the supply of a first power supply voltage. The power supply voltage abnormality detection unit detects that one of the power supply voltages is abnormal based on the ratio of the output voltage of the sensor to the first power supply voltage and the ratio of the output voltage of the sensor to the second power supply voltage. ..

With such a configuration, it is possible to detect that one of the first and second power supply voltages is abnormal by using the ratio of the output voltage of the common sensor and the first and second power supply voltages. ..

More preferably, the first microcomputer has a first conversion circuit that produces a first digital value according to the ratio of the output voltage of the sensor to the first power supply voltage. The second microcomputer has a second conversion circuit that produces a second digital value according to the ratio of the output voltage of the sensor to the second power supply voltage. The power supply voltage abnormality detector is composed of a first or second microcomputer, and one power supply is obtained by comparing the first and second digital values by communication between the first and second microcomputers. Detects that the voltage is abnormal.

With such a configuration, one of the first and second power supply voltages is abnormal by using the A / D conversion value of the sensor output voltage commonly input to the first and second microcomputers. Can be detected. Therefore, the output voltage of the sensor used for normal control is input to the first and second microcomputers, and the voltage divider circuit is arranged and the port for inputting the voltage divider is dedicated. It is possible to monitor the abnormality of the power supply voltage without newly providing the configuration of.

Alternatively, preferably, the fuel system further comprises a sensor that operates on the supply of a first supply voltage. The sensor has a specific timing at which the output voltage is fixed at a known constant value. When the voltage ratio of the output voltage of the sensor to the second power supply voltage deviates from a predetermined range including a reference value determined corresponding to a known constant value at a specific timing, the power supply voltage abnormality detection unit is used. Detects that one of the power supply voltages is abnormal.

With such a configuration, the microcomputer alone operates at a power supply voltage different from the power supply voltage of the sensor by using the output voltage of the sensor having a specific timing in which the output voltage is fixed to a known constant value. , One of the first and second power supply voltages can be detected as abnormal.

More preferably, the output voltage of the voltage divider circuit or sensor is input to the second microcomputer. The second microcomputer has a conversion circuit. The conversion circuit produces a digital value according to the ratio of the output voltage input to the second microcomputer to the second power supply voltage. The power supply voltage abnormality detection unit is configured by a second microcomputer, and detects that one of the power supply voltages is abnormal when the digital value deviates from a predetermined range.

With such a configuration, one of the first and second power supply voltages is abnormal by using the A / D conversion value in the second microcomputer to which the output voltage of the voltage divider circuit or the sensor is input. It can detect that there is.

According to the present invention, in a combustion device having a configuration in which a plurality of microcomputers are operated by using a plurality of power supply voltages, it is possible to reliably detect the occurrence of a phenomenon in which some power supply voltages are abnormal.

It is a schematic block diagram explaining the structure of the combustion apparatus according to Embodiment 1. FIG. It is a conceptual diagram for demonstrating the change of the output of the A / D converter when the power supply rise abnormality occurs. It is a flowchart explaining the control process for power supply voltage abnormality detection according to Embodiment 1. FIG. 5 is a schematic block diagram illustrating a configuration of a portion related to signal input from a sensor to a microcomputer in a combustion device according to a second embodiment. It is a conceptual diagram which shows the behavior of the A / D conversion value of the A / D converter with respect to the common sensor output voltage in the combustion apparatus according to Embodiment 2. FIG. It is a flowchart explaining the control process for power supply voltage abnormality detection according to Embodiment 2. It is a flowchart explaining the modification of the control process for the power supply voltage abnormality detection according to Embodiment 2. It is a schematic block diagram explaining the structure of the part concerning the signal input from the sensor to the microcomputer in the combustion apparatus according to the modification of Embodiment 2.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the figure are designated by the same reference numerals, and the explanations will not be repeated in principle.

[Embodiment 1]
FIG. 1 is a schematic block diagram illustrating a configuration of a combustion device 5 according to the present embodiment.

With reference to FIG. 1, the combustion device 5 includes a plurality of power supply circuits 10 and 20, a plurality of microcomputers 100 and 200, a combustion mechanism 500, and a sensor 600. Hereinafter, in the present embodiment, the points that include the components of the microcomputers 100 and 200 and only the configurations related to the abnormality detection function of the power supply voltage are described will be confirmed.

The combustion mechanism 500 comprehensively indicates a mechanism for generating heat by burning fuel, and is typically composed of a gas burner in a water heater, a gas burner in a fan heater, an oil burner, or the like. The operation of the combustion mechanism 500 is controlled by a plurality of microcomputers (hereinafter, also simply referred to as “microcomputers”) 100 and 200. For example, the microcomputers 100 and 200 can control the operation of the combustion mechanism 500 as the main microcomputer and the sub-microcomputer as in Patent Document 1. The operating power supply voltage values of the microcomputers 100 and 200 are common (for example, DC5V).

The combustion mechanism 500 is provided with a sensor 600. The sensor 600 is composed of, for example, a thermistor that detects the temperature of water heated by the combustion mechanism 500, a thermoelectric pair for detecting the presence or absence of combustion in the burner, and the like. The output signal of the sensor 600 is input to one or both of the microcomputers 100 and 200.

The power supply voltage VD is supplied to the power supply circuits 10 and 20 by the power supply wiring 6. The power supply voltage VD is generated by converting AC power from a commercial AC power supply into DC power by a power conversion circuit (not shown). The power supply circuits 10 and 20 and the microcomputers 100 and 200 operate by being connected to the ground wiring 7 that supplies a common ground voltage GND.

The power supply circuit 10 converts the power supply voltage VD into DC / DC to generate the power supply voltage VcA. The power supply voltage VcA is output to the power supply line 11. Similarly, the power supply circuit 20 converts the power supply voltage VD into DC / DC to generate the power supply voltage VcB. The power supply voltage VcB is output to the power supply line 21. The power supply voltages VcA and VcB are controlled by the operating power supply voltage values (for example, DC5V) of the microcomputers 100 and 200.

The microcomputer 100 operates by receiving the power supply voltage VcA from the power supply circuit 10 from the power supply line 11. The microcomputer 100 has a plurality of ports including ports 101 to 103, an analog / digital converter (hereinafter, also referred to as “A / D converter”) 110, and a CPU (Central Processing Unit) 120.

The A / D converter 110 has a function of converting an analog voltage input to any port of the microcomputer 100 into a digital value. Digital values are obtained by quantizing the analog voltage into 2 n steps using n bits (n: an integer greater than or equal to 2). Specifically, the A / D converter 110 generates a digital value according to the ratio of the input analog voltage to the power supply voltage VcA of the microcomputer 100.

The CPU 120 executes a predetermined control process for operating the combustion device 5 based on an A / D conversion value of a sensor signal input to the microcomputer 100, a signal indicating a user instruction (not shown), and the like. As a result of this control process, a control instruction for each component of the combustion device 5 is generated and output from another port (not shown) of the microcomputer 100. The output control instruction includes a signal for instructing the operation of the combustion mechanism (combustion start / stop or heat generation amount).

The microcomputer 200 operates by receiving the power supply voltage VcB from the power supply circuit 20 from the power supply line 21. The microcomputer 200 has a plurality of ports including ports 201 to 203, 210 which is also referred to as an “A / D converter”, and a CPU 220. The A / D converter 210 and the CPU 220 have the same functions as the A / D converter 110 and the CPU 120. That is, the A / D converter 210 generates a digital value according to the ratio of the input analog voltage to the power supply voltage VcB of the microcomputer 200.

The microcomputers 100 and 200 can communicate with each other by the output ports 102 and 202 and the input ports 103 and 203. That is, by receiving the output signal from the output port 102 at the input port 203, data can be transmitted from the microcomputer 100 to the microcomputer 200. Similarly, by receiving the output signal from the output port 202 at the input port 103, data can be transmitted from the microcomputer 200 to the microcomputer 100. In this way, the microcomputers 100 and 200 can control the operation of the combustion mechanism 500 while executing data communication.

In the combustion device 5, the calculation load of each microcomputer can be suppressed by controlling the combustion mechanism 500 by being shared by a plurality of microcomputers 100 and 200. It is also possible to utilize data communication to monitor whether the control operation by one microcomputer is normal or not by the other microcomputer. Alternatively, it is possible to improve the safety of the system by backing up the functions of the microcomputers.

Further, in the combustion device 5 according to the present embodiment, since the microcomputers 100 and 200 use different power supply voltages, a phenomenon that both the microcomputers 100 and 200 stop operating due to a failure of a single power supply circuit. Can be avoided. That is, in the combustion device 5, even if a part of the power supply voltage becomes abnormal, it can be expected that the microcomputer operating by the remaining normal power supply voltage can normally execute the stop processing for the voltage abnormality.

Generally, for the microcomputers 100 and 200, the operation guaranteed voltage range of the power supply voltage is predetermined as a spec value. That is, as a part of the microcomputer function, the control operation can be stopped when the power supply voltage is abnormal.

However, if the microcomputers 100 and 200 do not stop operating for some reason even if the power supply voltages VcA and VcB deviate from the guaranteed operation voltage range, the microcomputers 100 and 200 have a power supply voltage VcA that is higher or lower than usual. Alternatively, there is a possibility that the combustion mechanism 500 is controlled by using the digital value A / D converted according to VcB. As a result, as a result of the combustion mechanism 500 performing an operation different from the usual operation, there is a concern that an error may occur in the amount of heat generated.

The reset circuits 150 and 250 can be arranged for the microcomputers 100 and 200 in response to the decrease in the power supply voltage.

For example, the reset circuit 150 connected to the power supply line 11 generates a reset signal when the power supply voltage VcA drops below a predetermined lower limit voltage. The reset signal from the reset circuit 150 is input to the port 101 of the microcomputer 100 operated by the power supply voltage VcA.

Similarly, the reset circuit 250 connected to the power supply line 21 generates a reset signal when the power supply voltage VcB drops below a predetermined lower limit voltage. The reset signal from the reset circuit 250 is input to the port 201 of the microcomputer 200 operated by the power supply voltage VcB.

The microcomputers 100 and 200 are pre-programmed to execute the initialization process in response to the input of the reset signal. Therefore, it is possible to prevent the microcomputer 100 and / or 200 from executing an abnormal control process due to a decrease in the power supply voltage VcA and / or VcB. On the other hand, when the microcomputer function does not operate in response to an increase in the power supply voltage, there is a concern that the combustion mechanism 500 may operate differently from the usual operation.

Therefore, the combustion device 5 according to the present embodiment has a function of automatically detecting that one of the power supply voltages VcA and VcB is abnormal (hereinafter, also referred to as “power supply voltage abnormality”) in at least one of the microcomputers 100 and 200. It is configured to be equipped.

The combustion device 5 further includes a voltage dividing circuit 300 for dividing the power supply voltage VcA. The voltage dividing circuit 300 generates a voltage dividing voltage Vdv according to a predetermined voltage dividing ratio kr (0 <kr <1.0) based on the power supply voltage VcA on the power supply line 11 (Vdr = kr · VcA). For example, the voltage dividing circuit 300 has a voltage dividing ratio kr according to the electric resistance ratio of the resistance elements connected in series. That is, it is understood that the voltage dividing voltage Vdb is a voltage that changes according to a change in the power supply voltage VcA.

The voltage dividing voltage Vdb from the voltage dividing circuit 300 is input to the port 205 of the microcomputer 200 and converted into a digital value by the A / D converter 210.

FIG. 2 is a conceptual diagram for explaining a change in the output of the A / D converter when a power supply rise abnormality occurs. FIG. 2 shows the output of the A / D converter 210 of the microcomputer 200 that A / D converts the voltage dividing voltage Vdv of the power supply voltage VcA.

With reference to FIG. 2, the output value Ddv of the A / D converter 210 (hereinafter, also referred to as the A / D conversion value Ddv) is the voltage ratio kv (kv = Vdv) of the voltage dividing voltage Vdv with respect to the power supply voltage VcB of the microcomputer 200. It becomes a digital value according to / VcB).

The A / D conversion value Ddv is set to Ddv = Dmax when kv ≧ 1.0, and is set to Ddv = 0 when kv ≦ 0. For example, when n = 8, Dmax = 255 (“11111111”). When 0 <kv <1.0, the A / D conversion value Ddv is set to a value obtained by quantizing kv · Dmax. Further, the voltage ratio kv can be modified according to the following equation (1) from Vdv = kr / VcA.

kv = Vdv / VcB = kr ・ (VcA / VcB)… (1)
Therefore, when the power supply voltages VcA and VcB are at the same level, the voltage ratio kv = kr, so that the A / D converter 210 outputs a digital value Dr obtained by quantizing kr · Dmax (Ddv). = Dr). Here, since the voltage division ratio kr is known, the digital value Dr is a predetermined constant. The digital value Dr corresponds to the reference value of the A / D conversion value Ddv when the power supply voltage is normal.

From this state, when the power supply voltage VcB is normal but the power supply voltage VcA rises above the normal level, or when the power supply voltage VcA is at the normal level but the power supply voltage VcB drops below the normal level. Since the voltage ratio (VcA / VcB) increases, the A / D conversion value Ddb becomes larger than the reference value Dr.

Conversely, if the power supply voltage VcA is normal but the power supply voltage VcB rises above the normal level, or if the power supply voltage VcB is at the normal level but the power supply voltage VcA drops below the normal level. Since the voltage ratio (VcA / VcB) decreases, the A / D conversion value Ddb becomes smaller than the reference value Dr.

Therefore, the normal range Rdv including the reference value Dr set corresponding to the voltage dividing ratio of the voltage dividing circuit 300 can be set. The normal range Rdv can be set to have a margin for quantization error and calculation error. By setting the lower limit value D1 and the upper limit value D2 of the A / D conversion value Ddv in the normal range Rdv, when the A / D conversion value Ddv deviates from the normal range Rdv, one of the power supply voltages VcA and VcB is abnormal. Can be detected.

FIG. 3 is a flowchart illustrating a control process for detecting a power supply voltage abnormality according to the first embodiment. According to the configuration example of FIG. 1, the control process shown in FIG. 3 can be repeatedly executed by the CPU 220 of the microcomputer 200 at a predetermined cycle.

With reference to FIG. 3, the CPU 220 acquires the A / D conversion value Ddv of the voltage dividing voltage Vdv based on the power supply voltage VcA from the A / D converter 210 in step S100. Further, the CPU 220 compares the A / D conversion value Ddv with the predetermined lower limit value D1 and upper limit value D2 (FIG. 2) in step S110.

When Ddv> D2 (when YES is determined in S120), the CPU 220 proceeds to step S140 to detect a power supply voltage abnormality. When Ddv ≦ D2 (when NO is determined in S120), when Ddv <D1 (YES in S130), the CPU 220 proceeds to step S150 to detect a power supply voltage abnormality. On the other hand, when D1 ≦ Ddv ≦ D2 (when NO is determined in S130), the CPU 220 determines that the power supply voltages VcA and VcB are normal in step S160.

The CPU 220 notifies the microcomputer 100 that a power supply voltage abnormality has occurred in each of steps S140 and S150. In response to this, the microcomputer 100 can execute a process when the power supply voltage is abnormal, for example, a process of stopping the combustion device 5 accompanied by an operation stop of the combustion mechanism 500, as the main microcomputer. Further, the microcomputer 200 can execute the stop processing of the combustion device 5 as a sub-microcomputer in each of steps S140 and S150 or in response to a command from the main microcomputer (microcomputer 100). In the stop process, it is preferable to output information for notifying the occurrence of a power supply voltage abnormality by an error code or the like output on a display screen of a remote controller (not shown).

By adjusting the power supply voltages VcA and VcB so that the reset circuits 150 and 250 operate when a problematic voltage drop occurs, the lower limit value D1 and the upper limit value D2 of the normal range Rdv are the power supply voltage VcA and the upper limit value D2. It can be set to a value specialized for detecting an abnormal increase in VcB. In this case, in step S140, the occurrence of an abnormal increase in the power supply voltage VcA can be specified, and in step S150, the occurrence of an abnormal increase in the power supply voltage VcB can be specified. Conversely, even if the reset circuits 150 and 250 are not arranged, it is possible to detect that one of the power supply voltages VcA and VcB is abnormal by the control process of FIG.

As described above, according to the combustion apparatus according to the first embodiment, the voltage dividing voltage Vdv of the power supply voltage VcA is based on the A / D conversion value by the power supply voltage VcB, that is, the change of the power supply voltage VcB and the power supply voltage VcA. It is possible to detect that one of the power supply voltages VcA and VcB is abnormal by using the ratio with the voltage that changes according to. As a result, it is possible to promptly detect a power supply voltage abnormality that cannot be dealt with by the reset circuits 150 and 250 and may adversely affect the operation of the combustion mechanism 500, and prevent the abnormal operation of the combustion mechanism 500.

That is, in the configuration example of FIG. 1, the power supply voltage VcA corresponds to the "first power supply voltage", and the power supply voltage VcB corresponds to the "second power supply voltage". The microcomputer 100 and the power supply circuit 10 correspond to the "first microcomputer" and the "first power supply circuit", respectively, and the microcomputer 200 and the power supply circuit 20 correspond to the "second microcomputer" and the "second power supply circuit", respectively. Corresponds to each "power supply circuit". Further, the "power supply voltage abnormality detection unit" is realized by the control process of the microcomputer 200.

Further, contrary to the configuration example of FIG. 1, A / D conversion of the microcomputer 100 operated by the power supply voltage VcA is performed by setting the power supply voltage VcB as the "first power supply voltage" and the power supply voltage VcA as the "second power supply voltage". It is also possible to execute the same control process as in FIG. 3 by the microcomputer 100 by using the A / D conversion value of the divided voltage of the power supply voltage VcB by the device 110.

[Embodiment 2]
In the first embodiment, while the power supply voltage abnormality can be monitored by using the voltage dividing voltage, it is necessary to additionally arrange the voltage dividing circuit and the port 205 for inputting the divided voltage for the monitoring function. Become. In the second embodiment, a configuration example for detecting an abnormality in the power supply voltage will be described using a sensor output voltage commonly input to the microcomputers 100 and 200 for controlling the combustion device 5.

FIG. 4 shows a configuration relating to signal input from the sensor to the microcomputer in the combustion device according to the second embodiment. Even in the combustion apparatus according to the second embodiment, the configuration other than the portion shown in FIG. 4 is the same as that in FIG. 1, so that the detailed description will not be repeated. That is, as in the first embodiment, the microcomputer 100 operates with the power supply voltage VcA, while the microcomputer 200 operates with the power supply voltage VcB.

With reference to FIG. 4, the sensor 600 shown in FIG. 1 includes a thermistor 610 having an electrical resistance value Rt that varies with temperature. The thermistor 610 is connected in series with a resistance element (electrical resistance value R0) between the power supply line 11 for supplying the power supply voltage VcA and the ground wiring 7 via the node Ns. For example, the thermistor 610 is arranged in a water heater, which is an example of the combustion device 5, to detect the temperature of hot water discharged from the water heater, including hot water heated by the combustion mechanism 500.

The sensor output voltage Vsn from the thermistor 610 generated in the node Ns is a voltage obtained by dividing the power supply voltage VcA by a known electric resistance value R0 and an electric resistance value Rt that changes depending on the temperature. It can be indicated by an equation.

Vsn = VcA · Rt / (Rt + R0)… (2)
From the equation (2), it is understood that the sensor output voltage Vsn is a voltage that changes according to a change in the power supply voltage VcA.

The sensor output voltage Vsn is commonly input to the port 106 of the microcomputer 100 and the port 206 of the microcomputer 200. The A / D converter 110 outputs the A / D conversion value D1s of the sensor output voltage Vsn input to the port 106. Similarly, the A / D converter 210 outputs the A / D conversion value D2s of the sensor output voltage Vsn input to the port 206.

FIG. 5 is a conceptual diagram showing the behavior of the A / D conversion values of the A / D converters 110 and 210 with respect to the common sensor output voltage in the combustion apparatus according to the second embodiment.

With reference to FIG. 5, the A / D conversion value D1s in the microcomputer 100 (A / D converter 110) is digital according to the voltage ratio kA (kA = Vsn / VcA) of the sensor output voltage Vsn to the power supply voltage VcA. It becomes a value.

Here, when the voltage division ratio kt (kt = Rt / (Rt + R0)) according to the thermistor 610 shown in the formula (2) is used, kA = kt. Therefore, even if the power supply voltage VcA changes, the A / D conversion value D1s does not change.

On the other hand, the A / D conversion value D2s in the microcomputer 200 (A / D converter 210) is a digital value according to the voltage ratio kB (kB = Vsn / VcB) of the sensor output voltage Vsn to the power supply voltage VcB.

The voltage ratio kB is shown as kB = kt · (VcA / VcB) using the voltage division ratio kt. Therefore, the A / D conversion value D2s is obtained when the power supply voltage VcB is normal but the power supply voltage VcA rises above the normal level, or when the power supply voltage VcA is at the normal level but the power supply voltage VcB is at the normal level. If it is lower than, (VcA / VcB)> 1, so it becomes larger than the A / D conversion value D1s according to the voltage division ratio kt.

On the contrary, the A / D conversion value D2s is when the power supply voltage VcA is normal while the power supply voltage VcB rises above the normal level, or when the power supply voltage VcB is at the normal level but the power supply voltage VcA is at the normal level. If it is lower than, (VcA / VcB) <1, so it becomes smaller than the A / D conversion value D1s according to the voltage division ratio kt.

Therefore, in the combustion apparatus according to the second embodiment, when the A / D conversion values D1s and D2s are shown to be different values by comparing the A / D conversion values D1s and D2s using the communication between the microcomputers 100 and 200. In addition, it can be detected that one of the power supply voltages VcA and VcB is abnormal.

FIG. 6 is a flowchart illustrating a control process for detecting a power supply voltage abnormality in the combustion apparatus according to the second embodiment. The control process according to FIG. 6 is repeatedly executed by the microcomputers 100 and 200. Further, in FIG. 6, the power supply voltage abnormality is detected by the CPU 220 of the microcomputer 200, as in the first embodiment.

With reference to FIG. 6, the CPU 120 of the microcomputer 100 acquires the A / D conversion value D1s of the sensor output voltage Vsn input to the port 106 from the A / D converter 210 in step S200. Further, the CPU 120 transmits the A / D conversion value D1s from the output port 102 to the microcomputer 200 (input port 203) in step S210. In this state, the CPU 220 waits for notification of the detection result of the power supply voltage abnormality from the microcomputer 200 until a predetermined time elapses from the transmission of the A / D conversion value D1s.

On the other hand, the CPU 220 of the microcomputer 200 acquires the A / D conversion value D2s of the sensor output voltage Vsn input to the port 206 from the A / D converter 210 in step S300. Further, when the CPU 220 receives the A / D conversion value D1s transmitted from the microcomputer 100 in step S310, the CPU 220 determines in step S330 whether the A / D conversion values D1s and D2s match. For example, in step S330, it is determined whether or not | D1s-D2s | <ε (ε: predetermined value) is satisfied.

In steps S200 and S300, A / D conversion values D1s and D2s are acquired based on the sensor output voltage Vsn at a common timing by the synchronous processing. Alternatively, in step S210, information related to the acquisition timing of the A / D conversion value D1s is transmitted from the microcomputer 100 to the microcomputer 200, and in step S330, the A / D is based on the sensor output voltage Vsn at the same timing. It is also possible to select the conversion values D1s and D2s and use them as comparison targets.

When there is a difference exceeding the determination value ε between the A / D conversion values D1s and D2s (when the determination of YES in S330), the CPU 220 proceeds to step S340 to detect a power supply voltage abnormality. Further, in step S350, the CPU 220 transmits information indicating the occurrence of a power supply voltage abnormality from the output port 202 to the input port 103 of the microcomputer 100. As a result, the occurrence of the power supply voltage abnormality is notified to the microcomputer 100.

When the CPU 120 of the microcomputer 100 receives the notification of the power supply voltage abnormality from the microcomputer 200, the CPU 120 determines the YES determination in step S220 and executes the process at the time of the power supply voltage abnormality in step S230. For example, in step S230, as described above, the stop processing of the combustion device 5 that accompanies the stop of the operation of the combustion mechanism 500 as the main microcomputer is executed.

Similarly, in step S360, the CPU 220 executes a process when the power supply voltage is abnormal, for example, a process of stopping the combustion device 5 as a sub-microcomputer, which involves stopping the operation of the combustion mechanism 500, as the main microcomputer. The CPU 220 can also wait after the process of step S350 (notification of power supply voltage abnormality) and execute the process of step S360 in response to a command from the main microcomputer (microcomputer 100).

On the other hand, when the difference between the A / D conversion values D1s and D2s is smaller than the determination value ε (NO determination in S330), the CPU 220 skips the processing of steps S340 to S360 and causes a power supply voltage abnormality. The processing in this cycle is terminated without executing the notification of and the processing when the power supply voltage is abnormal.

In the CPU 120 (microcomputer 100), if the notification of the power supply voltage abnormality is not received even after a predetermined time has elapsed after step S210 (transmission of the A / D conversion value D1s), step S220 is set to NO and step S230 is performed. Skip and end the processing in this cycle.

By adjusting the reset circuits 150 and 250 as in the first embodiment, the control process according to FIG. 6 can be specialized in detecting an abnormality in the rise of the power supply voltage VcA and VcB. In this case, when YES is determined in step S330, it is further determined whether D2s> D1s or D2s <D1s, and when D2s> D1s, an abnormality in the rise of the power supply voltage VcA is detected and D2s <D1s. At this time, it is possible to detect an abnormality in the rise of the power supply voltage VcB. That is, also in the second embodiment, even if the reset circuits 150 and 250 are not arranged, it is possible to detect that one of the power supply voltages VcA and VcB is abnormal by the control process of FIG.

In the example of FIG. 6, the A / D conversion value is transmitted from the microcomputer 100 to the microcomputer 200, and the microcomputer 200 executes the detection process of the power supply voltage abnormality by comparing the A / D conversion values D1s and D2s. Contrary to this example, it is also possible to transmit the A / D conversion value from the microcomputer 200 to the microcomputer 100 and execute the comparison processing of the A / D conversion values D1s and D2s on the microcomputer 100 side.

According to the combustion apparatus according to the second embodiment, a circuit (voltage dividing circuit) for monitoring a power supply voltage abnormality is used by using the sensor output voltage Vsn commonly input to the microcomputers 100 and 200 for controlling the combustion apparatus 5. And, without arranging the input port to the microcomputer exclusively, it is possible to detect an abnormality in which one of the power supply voltages VcA and VcB rises as in the first embodiment.

In the configuration of FIG. 6, the A / D conversion value D2s (D2s = kt · (VcA / VcB)) in the microcomputer 200 is the A / D conversion value Ddv (Ddv =) in the microcomputer 200 in the first embodiment. Similar to kr · (VcA / VcB)), it is a conversion value of the divided voltage of the power supply voltage VcA with respect to the power supply voltage VcB. On the other hand, the A / D conversion value D2s is different from the A / D conversion value Ddv according to the fixed voltage division ratio kr in that the voltage division ratio kt changes according to the electric resistance value Rt of the thermistor 610.

Therefore, in the second embodiment, by comparing the A / D conversion values D1s and D2s in each of the microcomputers 100 and 200 by using the communication between the microcomputers, even if the voltage division ratio kr changes, the power supply voltage VcA and An abnormality in which one of VcB rises can be detected. That is, the power supply voltage abnormality can be detected at any timing.

In other words, if the sensor operates by the power supply voltage VcA and has a specific timing (for example, when the combustion device 5 is started) at which the output voltage becomes a known constant value, the sensor operates at the specific timing. It is also possible to execute the power supply voltage abnormality detection process similar to that of the first embodiment (FIG. 3) by the microcomputer 200 operating at the power supply voltage VcB.

FIG. 7 shows a flowchart illustrating a modified example of the control process for detecting a power supply voltage abnormality according to the second embodiment. The control process shown in FIG. 7 can be executed when the output voltage from the sensor having the specific timing as described above is input to the port 206.

With reference to FIG. 7, the CPU 220 determines in step S405 whether or not it is a specific timing of the sensor that outputs the sensor output voltage Vsn. For example, step S405 is determined to be YES at a predetermined period during execution of the start-up sequence of the combustion device 5 or at a predetermined control timing of the combustion device 5. Other than the above specific timing (when NO is determined in step S405), the processing after step S400 is skipped, and the processing for detecting the power supply voltage abnormality is not executed.

The CPU 220 executes steps S400 to S460 similar to steps S100 to S160 in FIG. 2 at a specific timing (when YES is determined in step S405).

In step S400, the A / D conversion value D2s of the sensor output voltage Vsn input to the port 206 is acquired, and the A / D conversion value Ddv in the first embodiment is used by using the A / D conversion value D2s. The same determination as in is executed. The lower limit value D1 and the upper limit value D2 for setting the normal range Rdv (FIG. 2) used in steps S420 and S430 are the above-mentioned references corresponding to the output voltage (known constant voltage) from the sensor at a specific timing. It can be predetermined to include a value.

As described above, in the combustion apparatus according to the second embodiment, the ratio of the divided voltage of the power supply voltage VcA to the power supply voltage VcB (first voltage ratio) is used, or the divided voltage of the power supply voltage VcA to the power supply voltage VcA. (Second voltage ratio) can be further used to detect an abnormality in which one of the power supply voltages VcA and VcB rises. As described above, when only the first voltage ratio related to the sensor output signal is used, the abnormality can be detected only at the specific timing, while both the first and second voltage ratios are used. Can detect anomalies at any time.

[Modified Example of Embodiment 2]
FIG. 8 is a circuit diagram for explaining a configuration according to a modified example of the second embodiment.

With reference to FIG. 8, in the configuration according to the modified example of the second embodiment, the sensor 600 shown in FIG. 1 includes a burner sensor 620. The burner sensor 620 can be configured by a thermocouple whose output voltage changes minutely between the formation and non-formation of a flame by the burner, which is an example of the combustion mechanism 500.

The amplifier circuit 630 is composed of an operational amplifier 635 operated by a power supply voltage VcA and resistance elements R1 to R5, and outputs a sensor output voltage Vsn that amplifies the output voltage of the burner sensor 620 to the signal line 190. Therefore, when the power supply voltage VcA changes, the amplification factor in the amplifier circuit 630 changes, so that the sensor output voltage Vsn also changes with respect to the same output voltage of the burner sensor 620. Therefore, it is understood that the sensor output voltage Vsn from the amplifier circuit 630 also changes according to the change in the power supply voltage VcA, similarly to the sensor output voltage from the thermistor 610.

The signal line 190 is connected to the port 106 of the microcomputer 100 and the port 206 of the microcomputer 200. As a result, the sensor output voltage Vsn is commonly input to the port 106 of the microcomputer 100 and the port 206 of the microcomputer 200, as in the second embodiment. Since the control processing by the microcomputers 100 and 200 for the input sensor output voltage Vsn is the same as that in the second embodiment, the detailed description will not be repeated.

In this way, even in the configuration in which the sensor output voltage Vsn is generated by the amplifier circuit or the like, the circuit (voltage dividing circuit) for monitoring the power supply voltage abnormality and the input port to the microcomputer are dedicated as in the second embodiment. It is possible to detect that one of the power supply voltages VcA and VcB is abnormal without arranging them.

In the second embodiment and its modification, an example of detecting a power supply voltage abnormality using a sensor output voltage Vsn that changes according to a change in the power supply voltage VcA has been described. That is, the power supply voltage VcA corresponds to the "first power supply voltage", and the power supply voltage VcB corresponds to the "second power supply voltage". The microcomputer 100 and the power supply circuit 10 correspond to the "first microcomputer" and the "first power supply circuit", respectively, and the microcomputer 200 and the power supply circuit 20 correspond to the "second microcomputer" and the "second power supply circuit", respectively. Corresponds to each "power supply circuit".

On the other hand, contrary to the examples of FIGS. 4 to 8, it is also possible to execute the same power supply voltage abnormality detection process based on the output voltage from the sensor operated by the power supply voltage VcB. That is, the power supply voltage VcB is defined as the "first power supply voltage", the power supply voltage VcA is defined as the "second power supply voltage", and the microcomputer 100 and the microcomputer 200 are referred to as the "first microcomputer" and the "second microcomputer", respectively. It is also possible to. In this case, the behaviors of D1s and D2s in FIG. 5 are interchanged, and similarly, it is possible to detect that one of the power supply voltages VcA and VcB is abnormal by comparing the A / D conversion values D1s and D2s. Further, the control process of FIG. 7 can be executed by the microcomputer 100 (CPU 120) by using the A / D conversion value D1s of the sensor output voltage Vsn by the power supply voltage VcA.

In the combustion device according to the present embodiment described above, the combustion mechanism accompanied by fuel combustion such as a water heater and a gas fan heater is controlled by a plurality of microcomputers, and a part of the plurality of microcomputers is operated by a different power supply circuit. Any configuration that operates with the generated power supply voltage can be applied in common.

That is, the number of microcomputers may be 3 or more, and the number of power supply circuits may also be 3 or more. However, a configuration in which power supply circuits are individually arranged corresponding to each microcomputer is not essential, and in a configuration including a plurality of power supply circuits, the first of a plurality of power supply voltages generated by the plurality of power supply circuits is the first. If the voltage (divided voltage or sensor output voltage) that changes depending on the power supply voltage is input to the microcomputer operating at another second power supply voltage, the ratio of the first power supply voltage to the second power supply voltage can be obtained. Based on this, the abnormality detection of the power supply voltage described in the first or second embodiment can be realized.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

5 combustion device, 6 power supply wiring, 7 grounding wiring, 10,20 power supply circuit, 11,21 power supply line, 100,200 microcomputer, 101-103,106,201-203,205,206 ports, 110,210 A / D Converter, 150, 250 reset circuit, 190 signal line, 300 voltage division circuit, 500 combustion mechanism, 600 sensor, 610 thermistor, 620 burner sensor, 630 amplification circuit, 635 optotype, D1s, D2s, Ddv A / D conversion value, Ddv output value, Dr reference value, GND ground voltage, Ns node, R0, Rt electrical resistance value, R1 to R5 resistance element, Rdv normal range, VD, VcA, VcB power supply voltage, Vdv voltage division voltage, Vsn sensor output voltage, kA, kB, kv voltage ratio, kr voltage division ratio.

Claims (7)

A combustion device that controls the combustion mechanism by multiple microcomputers with a common operating power supply voltage value.
Equipped with multiple power supply circuits
The plurality of microcomputers
A first microcomputer that operates by receiving a first power supply voltage generated by the first power supply circuit among the plurality of power supply circuits.
Including a second microcomputer that operates by receiving a second power supply voltage generated by the second power supply circuit among the plurality of power supply circuits.
A power supply that detects that one of the first and second power supply voltages is abnormal by using the ratio of the voltage that changes according to the change of the first power supply voltage to the second power supply voltage. A combustion device further equipped with a voltage abnormality detector. A voltage dividing circuit that divides the first power supply voltage at a predetermined voltage dividing ratio is further provided.
When the voltage ratio of the output voltage of the voltage dividing circuit to the second power supply voltage deviates from a predetermined range including a reference value determined corresponding to the voltage dividing ratio, the power supply voltage abnormality detecting unit said. The combustion device according to claim 1, which detects that one of the power supply voltages is abnormal. The output voltage of the voltage divider circuit is input to the second microcomputer.
The second microcomputer is
It has a conversion circuit that generates a digital value according to the ratio of the output voltage of the voltage dividing circuit input to the second microcomputer to the second power supply voltage.
The second aspect of the present invention, wherein the power supply voltage abnormality detecting unit is configured by the second microcomputer and detects that one of the power supply voltages is abnormal when the digital value deviates from the predetermined range. Combustion device. A sensor that operates by receiving the supply of the first power supply voltage is further provided.
The power supply voltage abnormality detection unit has an abnormality in one of the power supply voltages based on the ratio of the output voltage of the sensor to the first power supply voltage and the ratio of the output voltage of the sensor to the second power supply voltage. The combustion device according to claim 1, which detects that the voltage is high. The first microcomputer is
It has a first conversion circuit that produces a first digital value according to the ratio of the output voltage of the sensor to the first power supply voltage.
The second microcomputer is
It has a second conversion circuit that generates a second digital value according to the ratio of the output voltage of the sensor to the second power supply voltage.
The power supply voltage abnormality detection unit is configured by the first or second microcomputer, and by comparing the first and second digital values by communication between the first and second microcomputers. The combustion device according to claim 4, wherein the combustion device according to claim 4 detects that one of the power supply voltages is abnormal. A sensor that operates by receiving the supply of the first power supply voltage is further provided.
The sensor has a specific timing at which the output voltage is fixed at a known constant value.
When the voltage ratio of the output voltage of the sensor to the second power supply voltage deviates from a predetermined range including a reference value determined corresponding to the constant value at the specific timing. The combustion device according to claim 1, wherein it detects that one of the power supply voltages is abnormal. The output voltage of the sensor is input to the second microcomputer.
The second microcomputer is
It has a conversion circuit that generates a digital value according to the ratio of the output voltage of the sensor input to the second microcomputer to the second power supply voltage.
The sixth aspect of the invention, wherein the power supply voltage abnormality detecting unit is configured by the second microcomputer and detects that one of the power supply voltages is abnormal when the digital value deviates from the predetermined range. Combustion device.

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