JP2018054189A - Hot water device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a hot water passage from always being heated by a freezing preventive heater H even if a relay RL1 of which ON-OFF states are controlled by a microcomputer 11 is troubled to be fixed under its ON-state and further to enable a troubled location to be specified.SOLUTION: A first relay RL1 controlled in its ON-OFF operation by a microcomputer 11 and a second relay RL2 operated in its ON-OFF operation on the basis of comparison between an atmospheric temperature and a reference temperature are connected in series at an energization passage 13a for a freezing preventive heater H, the freezing preventive heater H is electrically energized through OFF operations of both the relays RL1, RL2, and when any one of the relays RL1, RL2 is operated ON, the freezing preventive heater is not electrically energized, so that even if the microcomputer 11 shows runaway, the circuit shows a short-circuit trouble or short-circuit trouble occurs, stopping of electrical energization for the freezing preventive heater H is increased in number.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a hot water device such as a water heater or a hot water heater.

  Conventionally, in a hot water apparatus such as a water heater, as disclosed in Patent Document 1 below, a freeze prevention heater for preventing freezing in a hot water channel has been provided at an appropriate place. Whether or not to energize is controlled by opening and closing a mechanical relay.

JP 2007-32004 A

  However, mechanical relays can be affected by abnormalities such as mechanical relay contact fixation, microcomputer runaway for mechanical relay operation commands, or failure of the drive circuit that outputs a drive signal to the mechanical relay based on the microcomputer operation command. May be fixed in the open state (hereinafter, this state is referred to as “open fixing failure”). In this case, the freeze prevention heater is energized even at a low temperature where freezing occurs. There is a risk of damage to the hot water channel due to freezing in the hot water channel without being performed.

  In addition, when water in the hot water channel is drained due to absence for a long time, etc., if the mechanical relay is fixed in a closed state (hereinafter, this state is referred to as “closed fixed failure”), Since the hot water channel without water is constantly heated, there is a possibility that piping will be burnt or unintended high temperature hot water may be generated.

  SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to prevent a hot water path from being constantly heated even when a closed / fixed failure of a relay (energization path opening / closing means) controlled to open and close by a microcomputer occurs. It is a second object of the present invention to enable error notification by detecting the occurrence of a failure that is not energized by the freeze prevention heater, and more preferably to make it possible to specify the failure site to some extent.

  To achieve the above object, the present invention provides a warm water channel, a freeze prevention heater provided at a predetermined portion of the warm water channel, and a first current path opening / closing means for opening and closing a current path to the freeze prevention heater. A temperature detection means for outputting a detection signal (typically a voltage signal) according to the temperature of a predetermined space or part (for example, the ambient temperature or the temperature of the hot water channel), and the detection signal of the temperature detection means And a controller for controlling whether or not to output a first heater ON command for closing the first energization path opening / closing means, the following technical means are taken: .

  That is, the hot water device of the present invention includes a second energization path opening / closing means provided in series with the first energization path opening / closing means for opening and closing the energization path, a detection signal input from the temperature detection means, and a predetermined signal. And a drive circuit configured to switch whether or not to output a second heater ON command for closing the second energization path opening / closing means based on the determination reference value. When both of the second heater ON commands are output, the freeze prevention heater is energized (Claim 1).

  According to the hot water device of the present invention, aside from the control unit that controls the opening / closing operation of the first energization path opening / closing means, based on the detection signal input from the temperature detection means and the predetermined determination reference value (typically Is provided with a drive circuit configured to switch whether or not to output a second heater ON command for closing the second energization path opening / closing means (based on a comparison result between the detection signal and the determination reference value). Therefore, the drive circuit opens the second energization path opening / closing means even when the first energization path opening / closing means is closed due to an abnormality of the control unit or the failure of the first energization path opening / closing means. If the conditions to be met are satisfied, the energization to the freeze prevention heater can be stopped by opening the second energization path opening / closing means.

  Typically, the control unit can be configured by a microcomputer, and the drive circuit can be configured by an analog circuit including a comparator, a voltage dividing circuit, and the like. The drive circuit is configured to output a second heater ON command (for example, a High signal is output as the second heater ON signal) when the temperature indicated by the detection signal is lower than the reference temperature indicated by the determination reference value. In addition, when the temperature indicated by the detection signal is equal to or higher than the reference temperature indicated by the determination reference value, the second heater ON command is not output (for example, a Low signal is output). The condition for the drive circuit to output the second heater ON command (the setting value of the determination reference value) may be the same as or different from the condition for the control unit to output the first heater ON command. Also good. For example, the control unit can be configured to start outputting the first heater ON command when the detection temperature indicated by the detection signal of the temperature detection means falls to a predetermined freeze prevention operation start temperature at which there is a risk of freezing, for example, 4 ° C. In this case, the drive circuit can be configured to start outputting the second heater ON command when the detected temperature decreases to 4 ° C., and the drive circuit outputs the first heater ON command from the control unit. The second heater ON command may be output when the temperature is lower than a predetermined temperature, for example, less than 20 ° C., which is higher than the starting temperature, and the second heater ON command may not be output when the temperature is 20 ° C. or higher.

  Although the output control of the first heater ON command by the control unit may be appropriate, it is preferable that the detection temperature indicated by the detection signal of the temperature detection means is equal to or higher than a predetermined freeze prevention operation start temperature. It can be configured to start outputting the first heater ON command when the temperature falls below, and to end the output of the first heater ON command when the detected temperature rises above a predetermined freeze prevention operation end temperature. The freeze prevention operation start temperature and the freeze prevention operation end temperature may be the same, but the freeze prevention operation end temperature is slightly higher than the freeze prevention operation start temperature in order to prevent chattering of the first energization path switching means ( For example, it is preferable to set so that it may be about 2-3 degreeC.

  The drive circuit can also have an appropriate configuration, but preferably, when the detected temperature indicated by the detection signal of the temperature detecting means falls from the determination reference value to less than the determination reference value, the second heater ON command starts to be output, When the detected temperature rises to the determination reference value or a value slightly higher than the determination reference value, the output of the second heater ON command can be terminated. Such hysteresis of the drive circuit can be realized by, for example, a positive feedback circuit of a comparator.

  The drive circuit may be configured so that the determination reference value varies depending on the open / close state of the first energization path opening / closing means, but whether or not the first energization path opening / closing means is closed. Regardless of the case, it is preferable that the determination reference value is constant.

  In the hot water apparatus according to the present invention, the drive circuit is configured to output a drive circuit monitoring signal corresponding to an opening / closing operation state of the second energization path opening / closing means to the control unit, and the control unit includes the temperature Even though the detection signal of the detection means is within a range where the second heater ON command is not output in relation to the determination reference value (for example, the detected temperature indicated by the detection signal is equal to or higher than the reference temperature indicated by the determination reference value). When the drive circuit monitoring signal indicating that “the second energization path opening / closing means is closing” is input, the drive circuit may be determined to be abnormal (Claim 2). . According to this, it is possible to specify that there is an abnormality in the drive circuit by a simple configuration and determination process. Such identification need not be exact, and can be determined to the extent that there is a high probability that the drive circuit is abnormal. In addition, the abnormality of the drive circuit can include a failure of a circuit portion that generates and outputs a drive signal, a failure of a circuit portion that generates and outputs a drive circuit monitoring signal, and the like.

  It is preferable that the controller can determine a failure of the temperature detection means (such as an open failure and / or a short-circuit failure). The abnormality determination of the drive circuit is normally confirmed by the failure determination of the temperature detection means. It may only be executed when According to this, it is possible to prevent the drive circuit that is operating normally from being determined to be “abnormal” based on the abnormal detected temperature due to the failure of the temperature detecting means.

  Furthermore, the hot water device of the present invention can include a heater monitoring circuit that outputs a heater monitoring signal to the control unit according to whether or not the freeze prevention heater is energized. Then, the control unit is within a range in which the detection signal of the temperature detection means is output in relation to the determination reference value and the second heater ON command is output (for example, the detection temperature indicated by the detection signal is indicated by the determination reference value). When the heater monitoring signal indicating that “the anti-freezing heater is energized” is input even though the first heater ON command is not output when the temperature is less than the reference temperature) It may be constituted so that it may be judged that it is a closed fixation failure of one energization way opening-and-closing means (Claim 3). According to this, it can be specified by a simple configuration and determination process that a closed fixing failure of the first energization path opening / closing means has occurred. The closed failure of the first energization path opening / closing means is caused by the contact of the first energization path opening / closing means being closed, the short circuit failure of the switching element constituting the drive circuit of the first energization path opening / closing means, or the heater. This can be caused by a short circuit to the power supply line of the output port of the ON command.

  In addition, the control unit is not determined to be abnormal in the drive circuit, and a range in which the second heater ON command is output in relation to the detection reference value of the detection signal of the temperature detection unit If the heater monitoring signal indicating that “the anti-freezing heater is energized” is not input even if the heater ON command is output, the first energization path opening / closing means is not properly fixed. It can be configured to determine that there is (claim 4). According to this, the second energization path opening / closing means due to the failure of the drive circuit is determined by determining whether the first energization path opening / closing means is open / fixed after the normality is confirmed by the abnormality determination of the drive circuit. It is possible to avoid erroneously determining that an open / fixed failure of the first energization path opening / closing means that is operating normally in spite of being in a state of not being closed. Note that the open / fixed failure of the first energization path opening / closing means is caused by the open contact of the first energization path opening / closing means, the open failure of the switching element constituting the drive circuit of the first energization path opening / closing means, the heater This can be caused by a short circuit to the ground of the output port of the ON command.

  The hot water apparatus of the present invention further includes a heater monitoring circuit that outputs a heater monitoring signal to the control unit according to whether or not the freeze prevention heater is energized, and the drive circuit includes the first monitoring circuit. A first threshold value is set as the determination reference value when the energization path opening / closing means is closed, and a second value different from the first threshold is set when the first energization path opening / closing means is open. A threshold value is set as the determination reference value, and the second threshold value is set so that a second heater ON command is output whenever the first energization path opening / closing means is open. (Claim 5). In such a configuration, the first threshold value is higher than the freeze prevention operation start temperature (for example, 3 to 5 ° C.) at which the control unit starts outputting the first heater ON command (for example, 10 to 30 ° C., more preferably 20). It is preferable to set the temperature to about. The second threshold value can be set to a value outside the signal range that can be output by the temperature detection means (for example, outside the output voltage range).

  According to this configuration, since the second energization path opening / closing means is normally closed when the first energization path opening / closing means is open, the output control state of the first heater ON command and the heater monitoring signal By confirming the consistency with the state, the first energization path switching means caused by closing and fixing of the contacts of the first energization path opening / closing means or the short circuit of the output port of the first heater ON command to the power supply line etc. Can be determined based on the heater monitoring signal. Therefore, it is not necessary to provide a monitoring port dedicated to determining the abnormality of the first power path switching means, and the closed fixed failure determination of the first power path switching means is performed even in products with a small number of available microcomputer ports. it can.

  Furthermore, according to the above configuration, since the second energization path opening / closing means opens when the detected temperature becomes equal to or higher than the first threshold when the first energization path opening / closing means is closed, the first energization path Even when an abnormality that is fixed in a state where the opening / closing means is closed occurs, if the detected temperature is equal to or higher than the first threshold value, the energization to the freeze prevention heater can be stopped by the function of the drive circuit. In addition, when there is no water in the pipe constituting the hot water channel, if the pipe is heated by the freeze prevention heater, the temperature detected by the temperature detecting means rises and rises to the first threshold (for example, 20 ° C.) or more. According to this, the first energization path opening / closing means is closed and fixed, the ambient temperature is around 0 ° C., and there is no water in the hot water channel. In this case, it is possible to prevent the hot water channel from being heated for a long time by the freeze prevention heater and causing the piping to be burnt.

  Further, the control unit does not output the first heater ON command, and the detection signal of the temperature detection means is within a range in which the second heater ON command is not output in relation to the first threshold value. The heater monitoring is configured to output the first heater ON command to determine whether the drive circuit is abnormal, and to indicate that the freeze prevention heater is energized by the output. When a signal is input, the drive circuit may be determined to be abnormal (Claim 6). According to this, the abnormality determination of the drive circuit can be performed based on the input state of the heater monitoring signal when the abnormality determination process is performed without providing the monitoring port for the abnormality determination of the drive circuit. The abnormality of the drive circuit may include contact welding of the second energization path switching means driven by the drive circuit in addition to the circuit failure of the drive circuit itself.

  Further, the control unit confirms the heater monitoring signal without outputting the first heater ON command when the detection signal of the temperature detecting means is within a range in which the first heater ON command is to be output. If the heater monitoring signal indicates that “the anti-freezing heater is energized”, it may be determined that the first energization path opening / closing means is a closed / fixed fault (Claim 7). . According to this, the first energization path opening / closing means based on the input state of the heater monitoring signal when the determination process is performed without providing the monitoring port for determining the closed / fixed failure of the first energization path opening / closing means. Can be determined.

  In addition, even if the control unit outputs the first heater ON command by detecting that the detection signal of the temperature detection means is within a range in which the first heater ON command is to be output, When the heater monitoring signal indicating that “the anti-freezing heater is energized” is not input, it may be determined that a predetermined failure has occurred (Claim 8). According to this, after the normality is confirmed by the abnormality determination of the drive circuit and the closed fixed failure determination of the first energization path opening / closing means, the drive is performed by determining that the predetermined failure is described above. Other faults other than a circuit abnormality or a failure to close the first energization path switching means (for example, open contact of the second energization path switching means, open adhesion of the contact of the first energization path switching means, It is possible to specify that the heater monitoring circuit is faulty).

  In addition, when the above-described failure or abnormality is detected, the control unit is preferably configured to perform error notification using a corresponding error code or error message. In the hot water device of the present invention, during normal operation (when the above abnormality or failure has not occurred), when at least one of the first and second heater ON commands is not output, the freeze prevention heater is energized. Can be configured not to be.

  As described above, according to the present invention, it is possible to stop energization of the freeze prevention heater by the opening operation of the second energization path opening / closing means even when the first energization path opening / closing means is closed and fixed. Thereby, it can prevent that a warm water channel is always heated. Furthermore, according to the present invention, it is possible to identify the failure part to some extent based on the correlation between the output control state of the heater ON command by the control unit, the detected temperature, the input state of the monitoring signal, and the like.

It is an operation principle figure of the instant water heater based on 1st Embodiment of the hot water apparatus of this invention. It is a circuit diagram which shows the principal part of the circuit structure relevant to drive control of the freeze prevention heater in the water heater. It is a circuit diagram which shows the principal part of the circuit structure relevant to drive control of the freeze prevention heater which concerns on 2nd Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an instantaneous water heater type latent heat recovery type high-efficiency water heater as an example of the hot water apparatus of the present invention, which includes a control board 1 for performing various controls, a combustion can body 2, and a hot water heater. Circuit 3 (warm water channel). Inside the can body 2, a combustion section 4 that generates combustion gas, a primary heat exchanger 5 disposed above the combustion section 4, and a secondary heat disposed further above the primary heat exchanger 5. An exchanger 6 (condensation heat exchanger) is provided. Further, a fan 7 that supplies combustion air to the combustion unit 4 is disposed below the combustion unit 4. A rotation speed sensor 71 is attached to the fan 7.

  The combustion unit 4 is divided into a plurality of (two in the illustrated example) combustion regions, and each combustion region is formed by a plurality of burners. A gas supply pipe 41 that supplies fuel gas as a combustion fuel from the fuel gas supply source side is connected to each combustion region. The gas supply pipe 41 is provided with an original gas electromagnetic valve 42 as a main plug and a gas proportional valve 43 for adjusting the gas supply amount in order from the fuel gas supply source side. A gas supply pipe 41 is branched for each combustion region on the downstream side of the gas proportional valve 43. A plurality of capacity switching valves SV1 and SV2 are individually provided corresponding to each combustion area, and the supply of fuel gas to each combustion area can be individually controlled by opening and closing each capacity switching valve SV1 and SV2. It has become. The fuel gas supplied to each combustion region is supplied to each burner through a gas passage provided for each burner, and the fuel gas and combustion air are mixed in the burner, and the mixed gas burns. As a result, combustion gas is generated.

  The primary heat exchanger 5 recovers the sensible heat of the combustion gas generated in the combustion unit 4, and the secondary heat exchanger 6 is the thermal energy of the combustion gas that cannot be recovered in the primary heat exchanger 5, that is, This is for recovering the latent heat and preheating the feed water before heating in the primary heat exchanger 5. The combustion exhaust gas after the heat energy is recovered by these heat exchangers is forcibly exhausted from the exhaust port 2 a provided in the upper part of the can body 2.

  The hot water supply circuit 3 includes a water inlet 31 for allowing tap water received from the water supply connection port to enter the secondary heat exchanger 6, and hot water heat-exchanged and heated by the secondary heat exchanger 6 and the primary heat exchanger 5. And a bypass passage 33 that branches from the water inlet 31 and supplies cold water to the hot water outlet 32. The water inlet 31 is provided with a can flow sensor 34 and a water inlet temperature sensor 35. A hot water flow rate control valve 36 and a hot water temperature sensor 37 are provided in the hot water path 32.

  An ignition plug 8 and a frame rod (extinguishing safety device) 9 are provided on the combustion can body 2 above the combustion unit 4. A drain collection tray 61 that collects condensed water as drain is provided below the secondary heat exchanger 6, and the collected drain is neutralized by the neutralization device 62 and then drained. In addition, sensors or measurement circuits for measuring various parameters necessary for hot water supply operation control, such as the incoming water temperature, the hot water temperature, the can body exhaust temperature, and the rotation speed of the fan 7, are provided at appropriate positions.

  In addition, an atmosphere temperature sensor 10 (temperature detection means) constituted by a thermostat is attached to a proper place in the casing of the water heater, and a plurality of freeze prevention heaters H are attached. This freeze prevention heater H can be provided particularly in a region where freezing is a problem, and in the illustrated example, in the vicinity of the lower end of the water inlet 31, in the vicinity of the lower end of the hot water outlet 32, in the vicinity of the bent portion of the primary heat exchanger 5, And the freeze prevention heater H is arrange | positioned in the vicinity of the neutralization apparatus 62, respectively. The freeze prevention heater H is preferably operated by energizing a commercial AC power supply, and the plurality of freeze prevention heaters H may be connected in series to the commercial AC power supply or may be connected in parallel. it can. Although the output heat quantity of each freeze prevention heater H can be designed as appropriate, for example, the temperature of the water inlet 31, the hot water outlet 32, and the pipe constituting the primary heat exchanger 5 is raised to about 80 ° C. without water inside. It can be made possible.

  The control objects such as the fan 7, spark plug 8, capacity switching valves SV 1 and SV 2, the original gas solenoid valve 42, the gas proportional valve 43, the hot water flow rate control valve 36, and the plurality of freeze prevention heaters H are the control board 1. The operation is controlled by. The control board 1 includes a microcomputer 11 (control unit) as a control center as shown in FIG. 2, and the microcomputer 11 acquires respective detection values from the sensors during the hot water supply operation, and detects them. The required amount of combustion heat is determined based on the value and the required hot water supply capacity, the number of stages of the combustion section 4 and the opening degree of the proportional valve 43 are controlled so that the required amount of combustion heat is obtained, and the hot water flow rate control valve 36 is opened. Control the degree. Further, the microcomputer 11 obtains the target rotational speed of the fan 7 by calculation so as to obtain an optimum air blowing amount corresponding to the required amount of combustion heat, and rotates the fan 7 at the target rotational speed.

  Further, the microcomputer 11 monitors the detection temperature indicated by the detection signal of the ambient temperature sensor 10 at least during the hot water supply operation stop, and the freezing prevention operation start temperature (for example, 3) that may freeze in the pipes constituting the hot water supply circuit 3. When the detected temperature decreases to ˜5 ° C., the first relay RL1 is closed by outputting the first heater ON command to the first relay drive circuit 16 described later, and the detected temperature is equal to or higher than the predetermined freeze prevention operation end temperature. When the temperature rises (for example, 5 to 7 ° C.), the freeze prevention operation control is performed so as to open the first relay RL1 by terminating the output of the first heater ON command. Further, the microcomputer 11 can be configured to perform the freeze prevention operation control even during the hot water supply operation.

  As shown in FIG. 2, the control board 1 has a heater drive circuit 13 for energizing the freeze prevention heater H from the commercial AC power supply, and whether or not the freeze prevention heater H is energized by the heater drive circuit 13. A heater monitoring circuit 14, an ambient temperature detection circuit 15 (temperature detection means), a first relay drive circuit 16, and a second relay drive circuit 17 (drive circuit for the second energization path opening / closing means RL2). Has been implemented. Further, on the power supply substrate 12 (see FIG. 1), an insulating switching converter 18 that generates and outputs a device operation power supply voltage (15 V DC power supply voltage) from a commercial AC power supply, and a control power supply voltage from the device operation power supply voltage. A regulator 19 that generates and outputs (5V DC power supply voltage) is provided.

  The heater drive circuit 13 includes an energization path 13a for energizing the commercial AC power supply voltage to both ends of the freeze prevention heater H, and first and second relays RL1 and RL2 (communication paths) provided in the middle of the energization path 13a. Electric circuit opening and closing means). The freeze prevention heater H is connected in series to the two relays RL1 and RL2, and the freeze prevention heater H is disposed between the two relays RL1 and RL2. In the present embodiment, normally-open contact type electromagnetic relays are used as the relays RL1 and RL2. When the drive current is supplied to the built-in electromagnetic coils L1 and L2, the operation is closed, and when the drive current is not supplied, the operation is opened. These electromagnetic coils L1 and L2 have a resistance component of about several hundred to several kΩ.

  The heater monitoring circuit 14 is mainly composed of a rectifier D that half-wave rectifies an AC voltage applied across the freeze prevention heater H, and a photocoupler PC. The photocoupler PC includes a light emitting diode on the input side and a phototransistor on the output side, and the light emitting diode on the input side is connected in series to the rectifier D via appropriate load resistors R1 and R2. The output side phototransistor has a negative terminal connected to the ground, and a positive terminal connected to the control power supply voltage via the pull-up resistor R3 and to the heater monitoring port of the microcomputer 11.

  Therefore, when the AC power supply voltage is applied to the freeze prevention heater H, a pulse signal corresponding to the cycle of the AC power supply voltage is a heater monitoring port of the microcomputer 11 as a heater monitoring signal indicating that the freeze prevention heater is energized. Is output. On the other hand, when the freeze prevention heater H is not energized, since the input voltage of the heater monitoring port of the microcomputer 11 is pulled up, the High signal is a heater monitoring signal indicating that the freeze prevention heater is not energized. It is output to the heater monitoring port of the microcomputer 11.

  The ambient temperature detection circuit 15 is constituted by a voltage dividing circuit formed by connecting the ambient temperature sensor 10 and the fixed resistor R4 in series, and a predetermined voltage (for example, 5V) is applied to both ends of the voltage dividing circuit. Has been. In this embodiment, a thermistor is used as the ambient temperature sensor 10, and since the ambient temperature sensor 10 is connected to the ground side of the fixed resistor R4, the output voltage of the voltage dividing circuit decreases as the ambient temperature increases. It has come to go. For example, when the atmospheric temperature is 20 ° C., the output voltage of the voltage dividing circuit is about 3V, when the atmospheric temperature is 4 ° C., the output voltage of the voltage dividing circuit is about 4V, and when the atmospheric temperature is 30 ° C., the output of the voltage dividing circuit is The temperature-resistance value characteristic of the ambient temperature sensor 10 can be designed so that the voltage is about 2.5V.

  The detection signal of the ambient temperature detection circuit 15, that is, the output voltage of the voltage dividing circuit is output to the temperature monitoring port of the microcomputer 11 and also to the second relay drive circuit 17.

  The first relay drive circuit 16 includes a switching element Q1 connected in series to the electromagnetic coil L1 of the first relay RL1, and the negative electrode side terminal of the electromagnetic coil L1 is connected to the ground via the switching element Q1. Yes. The positive terminal of the electromagnetic coil L1 is connected to the 15V power line. The switching element Q1 is ON / OFF controlled by a first heater ON command output from the microcomputer 11, and when the microcomputer 11 outputs a first heater ON command (in the example shown in the figure, a High signal is output), the switching element Q1 is As a result, the drive current is supplied to the electromagnetic coil L1, and the first relay RL1 is closed. On the other hand, when the microcomputer 11 does not output the first heater ON command (in the illustrated example, when the microcomputer outputs a Low signal or when the microcomputer 11 is set to the open output), the switching element Q1 is turned off, and thereby the electromagnetic coil L1 is supplied. The supply of the driving current is cut off, and the first relay RL1 is opened.

  The second relay drive circuit 17 includes a switching element Q2 connected in series to the electromagnetic coil L2 of the second relay RL2, and the negative electrode side terminal of the electromagnetic coil L2 is connected to the ground via the switching element Q2. Yes. The positive terminal of the electromagnetic coil L2 is connected to the 15V power line. The switching element Q2 is controlled to be turned on / off by the output signal of the comparator 17b (operational amplifier). The comparator 17b compares the voltage of the detection signal output from the ambient temperature detection circuit 15 with a constant reference voltage (determination reference value) output from the reference voltage generation voltage dividing circuit 17a, and indicates the detection signal. If the detected temperature is lower than the reference temperature indicated by the reference voltage, a High signal is output, and if the detected temperature is equal to or higher than the reference temperature, a Low signal is output. In the illustrated example, the detection signal of the ambient temperature detection circuit 15 is input to the non-inverting input terminal of the comparator 17b, and the reference voltage output from the reference voltage generating voltage dividing circuit 17a is input to the inverting input terminal of the comparator 17b. For example, if the reference voltage is 4 V (the reference temperature is 4 ° C.), the output of the comparator 17b becomes a high signal when the ambient temperature becomes less than 4 ° C., and the switching element Q2 is turned on by the high signal, Thus, the driving current is supplied to the electromagnetic coil L2, and the second relay RL2 is closed. The comparator 17b is provided with a positive feedback circuit (hysteresis circuit) so that the Hi output state is not switched to the Low output state unless the ambient temperature rises to, for example, 6 ° C. or higher.

  The second relay drive circuit 17 includes a monitoring circuit unit 17c that outputs a drive circuit monitoring signal corresponding to the open / close operation state of the second relay RL2 to the RL2 monitoring port of the microcomputer 11. When the switching element Q2 is turned on and the negative electrode side terminal of the electromagnetic coil L2 of the second relay RL2 is grounded, the monitoring circuit unit 17c notifies the microcomputer 11 that “the second energization path opening / closing means is closing”. When the switching element Q2 is turned off and the negative terminal of the electromagnetic coil L2 of the second relay RL2 is in an open state, the microcomputer 11 indicates to the microcomputer 11 that the "second signal" is output. The drive circuit monitoring signal (Low signal in the illustrated example) indicating that the energization path opening / closing means is open "is output.

  Specifically, the monitoring circuit unit 17c includes a switching element Q3 that is turned on / off by the potential on the negative side of the electromagnetic coil L2, and the RL2 monitoring port of the microcomputer 11 is connected to the control power supply voltage line via the switching element Q3. It is connected. The RL2 monitoring port is connected to the ground via a pull-down resistor R4. The switching element Q3 is composed of a pnp bipolar transistor, and its base (control terminal) is connected to the negative electrode side terminal of the electromagnetic coil L2 via the backflow prevention diode D2. Therefore, when the switching element Q2 is turned on, the base of the switching element Q3 is grounded, the switching element Q3 is turned on, and a High signal is input to the RL2 monitoring port of the microcomputer 11. On the other hand, when the switching element Q2 is turned off, the base of the switching element Q3 is pulled up and the switching element Q3 is also turned off, whereby the RL2 monitoring port is pulled down and a Low signal is input.

  Further, as will be described below, the microcomputer 11 determines the failure of the ambient temperature detection circuit 15, the abnormality determination of the second relay drive circuit 17, the closed / fixed failure determination of the first relay RL1, and the open failure of the first relay RL1. It is configured to make a determination.

  The failure determination of the ambient temperature detection circuit 15 (hereinafter referred to as “A determination”) is, for example, a failure of the ambient temperature detection circuit 15 when the detection signal voltage of the ambient temperature detection circuit 15 becomes an abnormal voltage outside the normal range. Can be determined. Further, for example, a circuit configuration is configured so that a failure determination voltage that causes the ambient temperature sensor 10 to self-heat under the control of the microcomputer 11 can be applied to the sensor 10, and the failure determination voltage is applied to the ambient temperature sensor 10 at a predetermined timing. Thus, whether or not an open failure or a short-circuit failure has occurred can be determined based on whether or not the temperature detected by the ambient temperature detection circuit 15 increases. If it is determined that the ambient temperature detection circuit 15 has failed due to such failure determination, the microcomputer 11 performs a predetermined error notification that the ambient temperature detection circuit 15 has failed.

  The abnormality determination of the second relay drive circuit 17 (hereinafter referred to as “B determination”) is, for example, a temperature detected by the ambient temperature detection circuit 15 of 4 ° C. (the second relay drive circuit 17 outputs a second heater ON command) The drive circuit monitoring signal indicating that “the second energization path opening / closing means is closing” is input to the RL2 monitoring port even though the temperature is equal to or higher than the reference temperature corresponding to the determination reference value to be started. When detected, it is determined that an abnormality of the second relay drive circuit 17, that is, a circuit failure in the relay drive circuit 17 or a short-circuit failure in which the RL2 monitoring port is short-circuited to a power supply line or the like has occurred. This B determination can be configured to be performed only when it is confirmed by the above A determination that the ambient temperature detection circuit 15 is operating normally. If it is determined by the B determination that the second relay drive circuit 17 is abnormal, the microcomputer 11 performs a predetermined error notification that the second relay drive circuit 17 is abnormal.

  In the closed / fixed failure determination (hereinafter referred to as “C determination”) of the first relay RL1, both of the above A determination and B determination are normal, and the temperature detected by the ambient temperature detection circuit 15 is the freeze prevention operation start temperature. When the temperature is lower than (4 ° C.), it can be performed before the first heater ON command is output, and “the freeze prevention heater is energized even though the first heater ON command is not output. When it is detected that a heater monitoring signal (pulse signal) indicating “is present” is input, it is determined that the first relay RL1 is closed and fixed, and the first relay RL1 is fixed while being closed. A predetermined error notification is performed. If normality is confirmed by the C determination, the microcomputer 11 starts the original freeze prevention operation, that is, starts outputting the first heater ON command.

  The open / fixed failure determination (hereinafter referred to as “D determination”) of the first relay RL1 can be performed when the microcomputer 11 is performing the freeze prevention operation, and the temperature detected by the ambient temperature detection circuit 15 is less than 4 ° C. ( Although the second relay drive circuit 17 is below the reference temperature at which the second heater ON command is output) and the first heater ON command is output, the “freezing prevention heater is energized” If the microcomputer 11 does not input a heater monitoring signal indicating that the first relay RL1 is open, it is determined that the first relay RL1 is open and fixed, and the first relay RL1 is fixed in the open state. Perform error notification.

  FIG. 3 shows a control circuit configuration according to the second embodiment of the present invention. The same components as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. explain.

  In the present embodiment, the monitoring circuit section of the second relay drive circuit 17 is not provided, and the reference voltage generating voltage dividing circuit 17a is connected to the control power supply line (5V) via the switching element Q4, and the microcomputer 11 When the first relay RL1 is closed by outputting the first heater ON command, the switching element Q4 is turned on and the reference voltage output from the reference voltage generating voltage dividing circuit 17a is set to 3 V (first threshold), for example. When the first relay RL1 is opened due to the output of the first heater ON command, the switching element Q4 is turned off and the reference voltage is set to 0 V (second threshold), for example.

  Further, a normally closed contact type electromagnetic relay is used as the second relay RL2, and when the comparator 17b outputs a Low signal (second heater ON command), the switching element Q2 is turned off and the electromagnetic of the second relay RL2 is output. The relay L2 is not energized, and the second relay RL2 is closed. On the other hand, when the comparator 17b outputs a High signal (corresponding to the fact that the second heater ON command is not output), the switching element Q2 is turned on to energize the electromagnetic relay L2 of the second relay RL2, and the second relay RL2 Is configured to open.

  The reference voltage output from the reference voltage generation voltage dividing circuit 17a is input to the non-inverting input terminal of the comparator 17a, and the detection signal from the ambient temperature detection circuit 15 is input to the inverting input terminal of the comparator 17b. . The detection signal voltage of the ambient temperature detection circuit 15 is, for example, a voltage greater than 4V and less than 5V when the ambient temperature is less than 4 ° C, and less than 4V and less than 3V when the ambient temperature is between 4 ° C and less than 20 ° C. The constant is set so that the voltage is large, and when the ambient temperature is 20 ° C. or higher, the detection signal is 3 V or lower and the voltage is higher than 0 V.

  Therefore, when the ambient temperature is 4 ° C. or higher, the microcomputer 11 does not output the first heater ON command and the first relay RL1 is opened, so the input voltage of the non-inverting input terminal of the comparator 17b is On the other hand, since the detection signal voltage of the ambient temperature detection circuit 15 input to the inverting input terminal of the comparator 17b is always higher than 0V, the comparator 17b always outputs a Low signal as the second heater ON command. .

  When the ambient temperature is less than 4 ° C., the microcomputer 11 outputs the first heater ON command and the first relay RL1 is closed, so that the input voltage at the non-inverting input terminal of the comparator 17b is 3V. On the other hand, since the detection signal voltage of the ambient temperature detection circuit 15 input to the inverting input terminal of the comparator 17b is higher than 4V, the comparator 17b outputs the Low signal to the second signal if any failure or abnormality does not occur. The heater ON command is always output.

  However, for example, the first heater ON command is constantly output regardless of the ambient temperature due to the runaway of the microcomputer 11 or the first heater ON command output port is short-circuited to the power supply line. If the ambient temperature becomes 20 ° C. or higher when a closed fixing failure occurs in which the first relay RL1 is closed in a closed state due to a short circuit failure of the switching element Q1 or the like, the ambient temperature detection circuit 15 This causes the detection signal voltage to become 3V or less, and the comparator 17b outputs a High signal. Accordingly, the second relay RL2 is driven to open, and the current supply to the freeze prevention heater H is stopped.

  In the present embodiment, the microcomputer 11 is configured to perform a failure determination of the ambient temperature detection circuit 15, an abnormality determination of the second relay drive circuit 17, a closed fixed failure determination of the first relay RL1, and other failure determinations. Has been.

  The failure determination of the ambient temperature detection circuit 15 can be the same as that in the first embodiment.

  In this embodiment, the abnormality determination of the second relay drive circuit 17 is, for example, an ambient temperature detected by the microcomputer 11 based on a detection signal from the ambient temperature detection circuit 15 is 25 ° C. or higher (second in relation to the first threshold value). Can be performed at a predetermined timing (for example, every fixed period). When the first heater ON command is output for abnormality determination of the second relay drive circuit 17, such abnormality determination processing is performed when a heater monitoring signal indicating that “the freeze prevention heater is energized” is input. The control is configured to determine that the two-relay drive circuit 17 is abnormal. If the abnormality determination is made, the microcomputer 11 performs a predetermined error notification indicating that the second relay drive circuit 17 is abnormal.

  The closed / fixed failure determination of the first relay RL1 is performed when the ambient temperature detected by the microcomputer 11 based on the detection signal from the ambient temperature detection circuit 15 is less than 4 ° C. (within the range in which the first heater ON command is to be output). Can be performed before the freeze prevention operation is started. That is, before starting the output of the first heater ON command, the heater monitoring signal is confirmed, and if the heater monitoring signal is a pulse signal (a signal indicating that “the freeze prevention heater is energized”), It is determined that the first relay RL1 is a closed and fixed failure. If such a failure determination is made, the microcomputer 11 performs a predetermined error notification indicating that the first relay RL1 is in a closed and fixed failure, and then always maintains the ambient temperature until a predetermined initialization of the error notification is performed. Regardless, the first heater ON command can be output. By constantly outputting the first heater ON command, when the ambient temperature rises to, for example, 20 ° C. as described above, the energization to the freeze prevention heater H is stopped, and accidental high temperature hot water can be prevented and the occurrence of piping burnout, etc. Can be prevented.

  If it is determined that the first relay RL1 is closed normally, the microcomputer 11 starts outputting the first heater ON command to close the first relay RL1 and starts the freeze prevention operation. . If the High signal is input as the heater monitoring signal during the freeze prevention operation, other failures other than the abnormality of the second relay drive circuit 17 and the failure of the first relay RL1 to be closed (for example, the failure of the heater monitoring circuit 14, the first 2 relay RL2 open / fixed failure, first relay RL1 open / fixed failure, etc.), and a predetermined error notification is made to indicate other failure.

  According to the second embodiment, the abnormality determination of the second relay drive circuit 17 can be performed without providing the microcomputer 11 with the monitoring port for determining the abnormality of the second relay drive circuit 17, The present invention can be applied to a model that does not exist.

  In addition, this invention is not limited to the said embodiment, A design change can be carried out suitably. For example, each energization path opening / closing means uses a mechanical relay in the above embodiment, but may be a semiconductor relay or other semiconductor switching element, or other mechanical switch. The power supply for the freeze prevention heater may be a direct current power supply. Further, the temperature detection means may be provided separately with a temperature sensor for control unit that outputs a detection signal to the control unit and a temperature sensor for drive circuit that outputs a detection signal to the second relay drive circuit, The space or part detected by these sensors may be the same or different.

3 Hot water channel (hot water supply circuit)
11 Microcomputer (control unit)
13a Current path 15 Temperature detection means (atmosphere temperature detection circuit)
17 Drive circuit (second relay drive circuit)
H Freezing prevention heater RL1 First energization path opening / closing means (first relay)
RL2 Second energization path switching means (second relay)

Claims (8)

A hot water channel, a freeze prevention heater provided at a predetermined part of the hot water channel, a first current path opening / closing means for opening and closing a current path to the freeze prevention heater, and detection according to the temperature of a predetermined space or part A temperature detecting means for outputting a signal, and a control for inputting whether a detection signal of the temperature detecting means is input and whether or not a first heater ON command for closing the first energization path opening / closing means is output. In a hot water device comprising a part,
Second energization path opening / closing means provided in series with the first energization path opening / closing means for opening and closing the energization path;
A drive configured to switch whether to output a second heater ON command for closing the second energization path opening / closing means based on a detection signal input from the temperature detection means and a predetermined determination reference value. And further comprising a circuit,
Thereby, when both the first and second heater ON commands are output, the freeze prevention heater is configured to be energized. The hot water device according to claim 1,
The drive circuit is configured to output a drive circuit monitoring signal corresponding to an opening / closing operation state of the second energization path opening / closing means to the control unit,
The control unit determines that the second energization path opening / closing means is closed even though the detection signal of the temperature detection means is within a range in which the second heater ON command is not output in relation to the determination reference value. When the drive circuit monitoring signal indicating "is present" is input, the hot water device is configured to determine that the drive circuit is abnormal. In the hot water device according to claim 2,
A heater monitoring circuit that outputs a heater monitoring signal according to whether the anti-freezing heater is energized to the control unit;
The control unit does not output the first heater ON command when the detection signal of the temperature detecting means is within a range in which the second heater ON command is output in relation to the determination reference value. Nevertheless, when the heater monitoring signal indicating that “the anti-freezing heater is energized” is input, it is determined that the first energization path opening / closing means is a closed / fixed failure. Hot water equipment characterized by. In the hot water device according to claim 2 or 3,
The control unit is not determined to be abnormal in the drive circuit, and the detection signal of the temperature detection unit is within a range in which the second heater ON command is output in relation to the determination reference value. If the heater monitoring signal indicating that “the anti-freezing heater is energized” is not input even if the heater ON command is output, it is an open / fixed failure of the first energization path opening / closing means. A hot water device characterized by being configured to determine. The hot water device according to claim 1,
A heater monitoring circuit that outputs a heater monitoring signal according to whether the anti-freezing heater is energized to the control unit;
In the drive circuit, when the first energization path opening / closing means is closed, the first threshold value is set as the determination reference value, and when the first energization path opening / closing means is open. Is configured such that a second threshold value different from the first threshold value is set as the determination reference value, and the second threshold value is always the second heater when the first energization path opening / closing means is open. A hot water device that is set to output an ON command. In the hot water device according to claim 5,
The control unit does not output the first heater ON command, and the detection signal of the temperature detecting means is within a range in which the second heater ON command is not output in relation to the first threshold value. In some cases, the heater monitoring signal indicating that the first heater ON command is output for abnormality determination of the drive circuit and that the freeze prevention heater is energized by the output is provided. A hot water apparatus configured to determine that the drive circuit is abnormal when input. In the hot water device according to claim 5 or 6,
The control unit checks the heater monitoring signal without outputting the first heater ON command when the detection signal of the temperature detection means is within a range in which the first heater ON command is to be output, A hot water apparatus, wherein the heater monitoring signal is configured to determine that the first energization path opening / closing means is in a closed / fixed fault if the freeze monitoring heater indicates that the freeze prevention heater is energized. In the hot water device according to claim 6, 7 or 8,
Even if the control unit outputs the first heater ON command by detecting that the detection signal of the temperature detection means is within a range where the first heater ON command should be output, A hot water device configured to determine that a predetermined failure has occurred when the heater monitoring signal indicating that the preventive heater is energized is not input.

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