JP2008156852A - Instantaneous hot-water supply type shower toilet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an instantaneous hot-water supply type shower toilet with a control unit which makes a determination time for the determination of frequencies of an AC source shorter than ever before, and which enhances determination reliability and safety. <P>SOLUTION: This instantaneous hot-water supply type shower toilet 1 comprises: a water supply pipeline 2; a flow control valve (3); a heating device (4) which is composed of a water temperature sensors (45 and 46) and an electric heater (41), and which is arranged midway through the water supply pipeline 2; and the control unit 5 which is provided with heater-temperature input portions (51 and 52), a frequency determination portion, a heating control portion and a flow control portion. The frequency determination portion comprises a zero-point detection circuit 53 for detecting a voltage zero point of the AC source, and a computing means (frequency computing logic portion 55) for obtaining a time interval of the detected voltage zero point and determining the frequencies F. The heating control portion (a temperature control logic portion 57 and a phase control circuit 54) performs control on the basis of the determined frequencies F. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an instantaneous hot water type shower toilet using an electric heater, and more particularly to a control device that controls the electric heater by detecting the frequency of an AC power source.

  Conventional shower toilets that eject hot water for washing from a washing nozzle are generally equipped with a hot water tank and always have a considerable amount of hot water. However, the hot water tank is large and requires an installation space, and heat retaining power is required to maintain the temperature of the hot water. Therefore, recently, from the viewpoint of space saving and energy saving, the development of a shower toilet equipped with an instantaneous water heater instead of a hot water tank has been promoted. As a configuration of the instantaneous hot water type shower toilet, it has been generally provided with a water supply pipe, a flow rate adjusting valve, an electric heater, a water temperature sensor, and a control device for controlling the temperature and flow rate of the hot water. The control device is configured to operate in response to a user's operation, and to supply hot water having an appropriate temperature by energizing the electric heater while detecting the water temperature.

  Shower toilets are widely used in general households, and a low-voltage AC power source is usually used as a power source. As is well known, either 50 Hz or 60 Hz is used as the frequency of the AC power supply in Japan depending on the region, and the frequency varies from country to country even overseas. And so that it can apply to either frequency, the shower toilet is shared with 50/60 Hz, and it is often configured that the control device itself determines the frequency and performs control. For example, each of the control devices disclosed in Patent Documents 1 to 3 includes a control unit that performs frequency determination.

The control unit of Patent Document 1 determines the frequency not only when the power is turned on but also when seated on the toilet seat, and prevents the frequency from continuing for a long time while being erroneously determined. In the frequency determination method, the voltage zero point of the AC power supply is detected, and the number of voltage zero points within a certain time, for example, 100 ms, is counted to determine whether the frequency is 50 Hz or 60 Hz. In Patent Document 2, the reliability is improved by determining the frequency at regular intervals even when there is no seating. Further, in Patent Document 3, erroneous determination caused by noise or power instability is removed by determining the frequency a plurality of times when the power is turned on.
Japanese Patent Publication No. 6-3035 Japanese Examined Patent Publication No. 7-6224 Japanese Patent Application Laid-Open No. 8-253962

  By the way, the control units of Patent Document 1 and Patent Document 2 require a determination time of 100 ms or more for frequency determination, and the control unit of Patent Document 3 requires a determination time of at least 200 ms. This determination time is not a problem in the conventional hot water tank type shower toilet, but the convenience for the user is lowered in the instantaneous hot water type shower toilet. This is because, in the hot water tank type, it is only necessary to supply hot water that is always available, whereas in the instantaneous hot water supply type, it is necessary to energize the electric heater immediately after the frequency determination to heat the water. Even if it is slight, the presence of waiting time may impair the convenience and comfort of the user.

  Furthermore, in the control units of Patent Documents 1 to 3, it cannot be asserted that there is no erroneous determination of frequency due to irregular noise or waveform distortion of the power supply voltage, and the reliability of the determination is further improved and safety is improved. Is preferably increased.

  SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned background. An instant hot water type shower toilet provided with a control device that shortens the determination time required for frequency determination of an AC power supply as compared with the prior art and further improves determination reliability and safety. I will provide a.

  The instant hot water type shower toilet according to the present invention includes a water supply pipe for supplying cleaning water to a cleaning nozzle, a flow rate adjusting valve disposed in the middle of the water supply pipe, a water temperature sensor for detecting a water temperature, and the water. A heating device that is provided in the middle of the water supply pipe, a water temperature input unit to which the detected water temperature data is input, and a frequency for determining the frequency of the AC power supply of the electric heater In an instantaneous hot water type shower toilet comprising a determination unit, a heating control unit that controls the electric heater, and a flow rate control unit that controls the flow rate adjustment valve, the frequency determination unit is configured to provide a voltage of the AC power source. A zero point detection circuit for detecting a zero point; and a calculation means for obtaining a time interval of the detected voltage zero point and further determining the frequency, wherein the heating control unit is based on the determined frequency. To control It is characterized in.

  The instant hot water type shower toilet of the present invention reduces the frequency determination time by determining the frequency of the AC power source from the time interval of the voltage zero point instead of the method of counting the number of voltage zero points within a certain time. Is the gist.

  First, the structure of the instant hot water type shower toilet of the present invention will be described. The water supply line is a part that connects a water supply source and a cleaning nozzle provided in the toilet and supplies cleaning water. A flow rate adjusting valve can be provided in the middle of the water supply pipeline. The flow rate adjustment valve is a part that adjusts the flow rate of water by opening and closing the water supply pipeline and adjusting the opening degree. For example, an electromagnetic valve that can be remotely controlled by an electric signal can be applied to the flow rate adjusting valve. A heating device can be further provided in the middle of the water supply pipeline. The heating device can be composed of a water temperature sensor that detects the water temperature and an electric heater that heats the water. The water temperature sensor detects the temperature of the water flowing in the water supply pipeline, and the temperature sensing part is preferably provided in the water supply pipeline. In order to avoid a time delay in detecting the water temperature, it is preferable that the heat capacity of the temperature sensing portion is small. For example, a ceramic heater that generates Joule heat can be used as the electric heater, and the heater can be arranged so as to be wound around a water supply pipe and heated through a pipe wall. Or you may make it heat water indirectly via a heat exchanger.

  The control device includes a water temperature input unit, a frequency determination unit, a heating control unit, and a flow rate control unit. For example, an electronic control device using a microcomputer is used, and control is performed with built-in software. It can be configured to do. A water temperature sensor can be connected to the water temperature input unit so that data of the detected water temperature can be input.

  The frequency determination unit can be composed of a zero point detection circuit and a calculation means. The zero point detection circuit can be configured using, for example, a known analog circuit that takes in the voltage signal of the AC power supply of the electric heater as an input and outputs a pulse at the voltage zero point. Alternatively, it may be configured using a digital circuit that reads the timing of the voltage zero point from voltage waveform data obtained by A / D converting a voltage signal and performing digital measurement. The calculation means recognizes the timing of the detected voltage zero point, and can obtain the time interval T of the voltage zero point by measuring the time with a built-in timer. Further, since the zero voltage point occurs twice during one AC cycle, the frequency F (= 1 / (2 × T)) can be obtained by dividing the reciprocal of the time interval T by 2. Alternatively, the frequency F may be determined as either 50 Hz or 60 Hz based on the obtained time interval T. The calculation of the time interval T and the frequency F by the calculation means can be performed by the software of the electronic control device described above.

  The heating control unit controls energization of the electric heater based on the frequency determined by the frequency determination unit in order to raise the detected water temperature to a set appropriate temperature. The flow rate control unit controls the opening and closing and the opening degree of the flow rate adjustment valve in order to realize the set flow rate.

  In addition to the above, the control device includes an operation unit that instructs the user to perform cleaning, sets a desired water temperature, flow rate, nozzle position, and the like, and a seating detection unit that automatically detects the user's seating. You may do it.

  Next, the frequency determination method, operation and action of the instant hot water type shower toilet of the present invention will be described.

  It is preferable that the frequency determination unit operates immediately before the heating control unit energizes the electric heater and further operates during energization. Since warm water is required when the user instructs cleaning, the heating control unit energizes the electric heater, but it is preferable that the frequency determination unit determine the frequency of the AC power supply immediately before energization. Furthermore, it is preferable to determine the frequency even during energization. In addition, it is preferable to determine the frequency when the electric heater is energized to prevent freezing of water in the water supply pipeline. By determining the frequency immediately before and during energization, the electric heater is not controlled at the wrong frequency, and safety is improved.

  The frequency determination unit discards the determined time interval as invalid when it is out of a specified range, counts up the number of invalid times and repeats an operation for obtaining the time interval, and before the number of invalid times reaches the specified number, The frequency may be determined when a valid time interval within the range is obtained, and it may be determined that the apparatus is abnormal when the invalid count reaches a specified count.

  In preparation for the case where the voltage zero point cannot always be detected correctly due to the influence of electrical noise or power supply instability, a method of confirming the effectiveness of the obtained time interval can be used. As will be described in detail below, the time interval of the zero voltage point is 10 ms at a frequency of 50 Hz and 8.3 ms at a frequency of 60 Hz, and a width of an effective specified range can be provided for these two values. If the obtained time interval is within one of the specified ranges, the frequency is determined as 50 Hz or 60 Hz as valid data, and invalid data can be determined when the frequency is out of the specified range. In the case of invalid data, it is possible to repeat the operation of counting up the number of invalid times and obtaining the time interval again. If valid data is obtained before the invalid count reaches the specified count, the frequency can be determined. If the invalid count reaches the specified count, the frequency cannot be determined and the device can be determined to be abnormal. . It is preferable to configure so that the operation of the control device is interrupted and an abnormality is displayed or notified when the device is abnormal.

  According to the above-described frequency determination method, the zero voltage point is correctly detected in normal operation, the frequency is determined at most about 10 ms, and the determination time is significantly shortened compared to the conventional method. If the voltage zero point is not correctly detected due to accidental noise or the like, the correct voltage zero point is detected by the re-operation, and the correct frequency is determined. If the frequency cannot be determined due to constant noise or power supply instability, it is determined that the apparatus is abnormal, and the operation is not performed with the frequency unknown. Furthermore, since the user is aware of the device abnormality, measures can be taken. As described above, the reliability of frequency determination is further improved, and the safety is improved with the fail-safe function.

  It is preferable that the heating control unit controls an energization phase of the AC power supply and supplies the electric heater to the electric heater.

  The present invention is particularly effective when the heating control unit controls the energization phase of the AC power supply. This is because in the method of controlling the energization phase using a power semiconductor such as a thyristor, the basis of control is a cycle time of one cycle of alternating current, and it is a prerequisite to determine the correct frequency. is there.

  The heating control unit performs PI control including a proportional term and an integral term with respect to the detected water temperature, and the constant of the integral term is variable depending on the determined frequency. May be.

  In order to raise the detected water temperature to a set appropriate temperature, the heating control unit may perform PI control (Proportional and Integral Control). That is, the electric heater may be controlled so that a sum value of the heat amount of the proportional term proportional to the difference between the detected water temperature and the set temperature and the heat amount of the integral term proportional to the integral amount of the water temperature change is generated by the electric heater. The feedback of the detected water temperature and the update of the control conditions are preferably performed using an integral multiple of the cycle time as a control cycle. Then, by appropriately setting the constants of the proportional term and the integral term according to the structure of the heating device, it is possible to realize a smooth convergence characteristic of the water temperature change quickly and without overshoot. In addition, since the integral term involves a control cycle that is an integral time, if the integral term constant is variable depending on the frequency, the convergence characteristics of the water temperature change are further improved. Practically, two types of integral term constants for 50 Hz and 60 Hz are prepared, and can be selectively used based on the determined frequency.

  According to the instant hot water type shower toilet of the present invention described above, since the frequency determination unit that detects the voltage zero point and obtains the frequency from the time interval is provided, the frequency determination time can be significantly shortened compared to the conventional case. . Further, in the aspect in which the heating control unit performs frequency determination immediately before and during the energization of the electric heater, the electric heater is not energized and controlled with the wrong frequency, and safety is improved. Furthermore, in the aspect in which the validity of the time interval of the zero voltage point is confirmed, determination reliability and safety can be further improved.

  The present invention is particularly effective when the heating control unit controls the energization phase of the AC power supply. In particular, when performing PI control on the detected water temperature, the constant of the integral term is variable depending on the frequency. As a result, the convergence characteristics of the water temperature change can be made extremely good.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a block diagram illustrating the configuration of an instantaneous hot water shower toilet according to an embodiment of the present invention. The instant hot water type shower toilet 1 of the embodiment includes a water supply pipe 2, a flow rate adjustment / water channel switching valve 3, a heater unit 4, an electronic control device 5, and an operation unit 6. In addition, the arrow in a figure has shown the flow of a signal and control.

  The water supply line 2 is a part that is connected to a water supply source and supplies cleaning water to a cleaning nozzle provided in the toilet. The flow rate adjustment / water channel switching valve 3 corresponding to the flow rate adjustment valve is disposed in the middle of the water supply pipeline 2, and performs the switching of the water channel and the flow rate adjustment by opening and closing the water supply pipeline 2 and adjusting the opening degree. It is. The flow rate adjustment / water channel switching valve 3 is an electromagnetic operation method and is controlled by the control device 5.

  The heater unit 4 corresponding to the heating device is disposed in the middle of the water supply pipe 2. The heater unit 4 includes a ceramic heater 41, an inlet water temperature detection thermistor 45, and an outlet water temperature detection thermistor 46. The ceramic heater 41 is a resistor that generates Joule heat, and is disposed inside the water supply pipe 2 so as to heat the water in the pipe 2. Further, the ceramic heater 41 is wired so as to be energized from a phase control circuit 54 of the control unit 5 described later. The two thermistors 45 and 46 are water temperature sensors that are provided at the inlet and the outlet of the water supply pipe 2 in the heating device 4 and detect the water temperature. Further, the output lines of the two thermistors 45 and 46 are connected to the thermistor input circuits 51 and 52 of the electronic control unit 5, respectively.

  The electronic control unit 5 includes two sets of thermistor input circuits 51 and 52, a zero point detection circuit 53, a phase control circuit 54, and a microcomputer 55. A frequency calculation logic unit 56 and a temperature control logic unit are configured by software of the microcomputer 55. 57 is realized. The two sets of thermistor input circuits 51 and 52 corresponding to the water temperature input unit pass the data of the inlet water temperature and the outlet water temperature detected by the inlet water temperature detection thermistor 45 and the outlet water temperature detection thermistor 46 to the temperature control logic unit 57. is there.

  The frequency determination unit includes a zero point detection circuit 51 and a frequency calculation logic unit 56. The zero point detection circuit 51 is a circuit that receives the voltage V of the low-voltage AC power supply, detects the voltage zero point, and outputs a predetermined zero point signal S0. The frequency calculation logic unit 56 measures the time interval T of the two zero point signals S0 with a built-in timer, and determines whether the frequency F is 50 Hz or 60 Hz. The confirmation of the validity of the time interval T performed by the frequency calculation logic unit 56 will be described in detail in a later flowchart.

  The heating control unit includes a temperature control logic unit 57 and a phase control circuit 54. The temperature control logic unit 57 determines the load factor of the ceramic heater 41 based on the frequency F determined by the frequency calculation logic unit 56 and the water temperature data received from the two sets of thermistor input circuits 51 and 52. An energization start phase P1 suitable for the load factor is calculated, and a control signal is output to the phase control circuit 54 as a command. The phase control circuit 54 is a circuit that controls the phase of the low-voltage AC power supply and supplies the ceramic heater 41 with a thyristor. That is, the phase control circuit 54 supplies a low-voltage AC power source to the ceramic heater 41 only between the commanded start-up phase P1 and the next voltage zero point, and controls the amount of heat generation. . For example, when the energization start phase P1 is 60 °, the ceramic heater 41 generates heat only in the range of the positive voltage phase 60 to 180 ° and the negative voltage phase 240 to 360 °.

  The operation unit 6 includes a cleaning switch for instructing cleaning, a setting switch for setting a desired water temperature and flow rate, and a display unit for displaying an operation state, so that the user can check the operation and display of the switch. Yes. The operated information is recognized by the microcomputer 55 and is reflected in the control.

  Note that all the electrical components including the control device 5 are supplied with power by branching a low-voltage AC power supply.

  Next, the operation procedure and operation of the instant hot water shower toilet 1 of the embodiment of FIG. 1 will be described with reference to FIG. FIG. 2 is a flowchart for explaining the overall operation of the instant hot water type shower toilet 1 of the embodiment, and item numbers with parentheses in the figure are described correspondingly in the following explanation.

  When the low-voltage AC power is turned on (1), the electronic control unit 5 first checks whether or not the water temperature data is below a certain temperature (2). When the water temperature is equal to or lower than a certain temperature, the ceramic heater 41 is energized to prevent freezing of the water in the water supply pipe 2, but the frequency F of the power source is determined immediately before energization (3). Next, the energization start phase P1 is calculated based on the determined frequency F and the water temperature, the ceramic heater 41 is energized, and the water in the water supply line 2 is heated (4). The electronic control unit 5 determines the frequency F of the power source at any time during energization (5). Next, the electronic control unit 5 checks whether or not the cleaning switch of the operation unit 6 is operated (6). When the washing switch is not turned on, the electronic control unit 5 enters the standby mode, and the water temperature confirmation (2), frequency determination (3) (5) and energization (4) for preventing freezing as necessary, repeat.

  When the cleaning switch is turned on, the electronic control unit 5 enters the cleaning mode, and the frequency determination (7) of the power source immediately before energization, the energization of the ceramic heater 41 (8), and the frequency determination during energization (9) are performed. . When the water temperature reaches an appropriate temperature, the flow rate adjustment / water channel switching valve 3 is opened and hot water is supplied to the cleaning nozzle so that cleaning can be performed (10). While the cleaning is being performed, the electronic control unit 5 confirms whether or not the cleaning switch has been operated (11), and the ceramic heater 41 is continuously energized (8) while it is not turned off. The frequency determination (9) is performed. When the washing switch is turned off, the electronic control unit 5 closes the flow rate adjustment / water channel switching valve 3 (12) and returns to the standby mode in which the water temperature is confirmed (2).

  When it is determined that the device is abnormal immediately before energization or during frequency determination (3), (5), (7), and (9) during energization, the electronic control unit 5 stops its operation and the display unit of the operation unit 6 An abnormality is displayed in (13).

  Next, details of the frequency determination operation immediately before energization will be described with reference to FIG. FIG. 3 is a flowchart for explaining the frequency determination operation of the instantaneous hot water shower toilet 1 according to the embodiment, and the alphabetic symbols with parentheses in the figure are described correspondingly in the following description.

  When performing frequency determination, the frequency calculation logic unit 56 first clears an invalid counter provided therein (a) and clears a built-in timer (b). Next, the interrupt reception of the zero point signal S0 is started (c), and the zero point signal S0 is waited (d). When the zero point detection circuit 51 detects the voltage zero point and outputs the zero point signal S0, the frequency calculation logic unit 56 detects this zero point signal S0 and starts a timer (e). The presence or absence is confirmed (f). When the next zero point signal S0 is detected before the predetermined time-out value is reached, the timer is stopped (g) and the time interval T between the two zero point signals S0 is counted (h).

  Here, the effectiveness of the obtained time interval T is confirmed (i). Specifically, the width of the effective specified range is set for the binary values of 10 ms and 8.3 ms, and it is confirmed whether or not the time interval T falls within either width. If the time interval T falls within the width centered at 10 ms, the frequency F is determined to be 50 Hz. If the time interval T falls within the width centered at 8.3 ms, the frequency F is determined to be 60 Hz (j).

  If the timer reaches a timeout value when determining the time interval T (k), and if the time interval T is determined but does not fall within either range, the frequency determination is invalid and the invalid counter is Counts up (l). If the invalid counter is less than or equal to the specified number (m), the process returns to timer clear (b) and frequency determination is performed again. When the invalid counter reaches the specified number of times, it is determined that the device is abnormal (n), and the display returns to the abnormality display (13) in FIG.

  The frequency determination operation during energization is similar to the frequency determination operation immediately before energization shown in FIG. 3, but there are some differences. That is, the frequency F1 determined during energization is compared with the frequency F determined immediately before energization, and in the unlikely event that the frequency F1 determined later is provided to the temperature control logic unit 57. Further, when frequency determination during energization is invalid, only the invalid counter is incremented, and frequency determination is not retried. This is because it is preferable to prioritize the energization of the ceramic heater 41 over the retry because the frequency determination opportunities are given at regular time intervals by interrupt processing.

  Next, PI control performed by the temperature control logic unit 57 will be described. PI control is a technique for controlling the amount of heat generated by the ceramic heater 41 by the sum of the proportional term and the integral term. The proportional term is a calorific value proportional to the difference between the detected water temperature and the set temperature, and has an effect of bringing the water temperature close to the set temperature. However, since the amount of heat generation decreases as the set temperature is approached, the convergence characteristics are poor, and an integral term is used to compensate for this. The integral term is a calorific value proportional to the integral amount of the water temperature change, and the convergence characteristic can be improved by multiplying by an appropriate constant and adding up to the proportional term. The temperature control logic unit 57 has two types of integral term constants, one for 50 Hz and one for 60 Hz, and uses them properly based on the frequency F determined by the frequency calculation logic unit 56.

  FIG. 4 is a diagram for explaining the experimental results of temperature control using the instant hot water type shower toilet 1 according to the embodiment. FIG. 4A shows the case where two types of constants of the integral term of PI control are used separately, and FIG. This is a case where the constant of the term is fixed for 60 Hz. In the figure, the horizontal axis indicates the elapsed time, and the vertical axis indicates the electric power of the ceramic heater 41, and the lower stage indicates the water temperature at the outlet of the cleaning nozzle. The graph shows the case where the power supply frequency is 50 Hz with a solid line and the case where it is 60 Hz with a broken line. In FIG. 4A, the graphs with frequencies of 50 Hz and 60 Hz almost overlap each other, and the water temperature at the outlet of the cleaning nozzle quickly rises and then quickly converges to an appropriate temperature. In FIG. 4B, the graph of the power supply frequency 50 Hz indicated by the solid line is different from FIG. That is, the water temperature at the outlet of the cleaning nozzle vibrates after rising sharply, and the convergence property to an appropriate temperature is inferior. This is because the power of the ceramic heater 41 shown in the upper graph increased or decreased excessively, that is, the integral term constant was for 60 Hz and was incompatible with the power supply frequency of 50 Hz. Therefore, this experimental result confirmed the effect of a mode in which the constant of the integral term of PI control is variable depending on the frequency.

It is a block diagram explaining the structure of the instant hot water supply type shower toilet of the Example of this invention. 2 is a flowchart illustrating an overall operation in the embodiment of FIG. 2 is a flowchart illustrating an operation of frequency determination in the embodiment of FIG. In the embodiment of FIG. 1, it is a figure explaining the experiment result of temperature control, (A) is when using two kinds of constants of the integral term of PI control, (B) is fixing the constant of the integral term for 60 Hz. This is the case.

Explanation of symbols

1: Instant hot water shower toilet 2: Water supply line 3: Flow rate adjustment / water channel switching valve 4: Heater unit
41: Ceramic heater
45: Inlet water temperature detection thermistor 46: Outlet water temperature detection thermistor 5: Electronic control unit
51, 52: Thermistor input circuit 53: Zero point detection circuit
54: Phase control circuit 55: Microcomputer
56: Frequency calculation logic unit 57: Temperature control logic unit 6: Operation unit V: Voltage S0: Zero point signal F: Frequency P1: Energization start phase

Claims (5)

A water supply line comprising a water supply line for supplying cleaning water to the cleaning nozzle, a flow rate adjusting valve disposed in the middle of the water supply line, a water temperature sensor for detecting the water temperature, and an electric heater for heating the water. A heating device disposed in the middle of the pipe, a water temperature input unit to which the detected water temperature data is input, a frequency determination unit that determines the frequency of the AC power supply of the electric heater, and heating that controls the electric heater In an instantaneous hot water type shower toilet provided with a control unit having a control unit and a flow rate control unit that controls the flow rate adjustment valve,
The frequency determination unit includes: a zero point detection circuit that detects a voltage zero point of the AC power supply; and a calculation unit that obtains a time interval of the detected voltage zero point and further determines the frequency, and the heating The instantaneous hot water type shower toilet, wherein the control unit performs control based on the determined frequency.   The instantaneous hot water type shower toilet according to claim 1, wherein the frequency determination unit operates immediately before the heating control unit energizes the electric heater and further operates during energization.   The frequency determination unit discards the determined time interval as invalid when it is out of a specified range, counts up the number of invalid times and repeats an operation for obtaining the time interval, and before the number of invalid times reaches the specified number, 3. The frequency according to claim 1, wherein the frequency is determined when the effective time interval within the range is obtained, and the apparatus is determined to be abnormal when the invalid count reaches a specified number. Instant hot water shower toilet.   The instantaneous hot water type shower toilet according to any one of claims 1 to 3, wherein the heating control unit controls an energization phase of the AC power supply to supply the electric heater to the electric heater.   The heating control unit performs PI control including a proportional term and an integral term with respect to the detected water temperature, and a constant of the integral term is variable depending on the determined frequency. 4. Instant hot water type shower toilet.

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