JP5077635B2 - Electric heating instantaneous water heater and control method thereof - Google Patents

Description

  The present invention relates to an electric heating instantaneous water heater used for a shower toilet or the like, and more particularly to a method for controlling water temperature.

  Conventional shower toilets that eject hot water for washing from nozzles have been generally equipped with a hot water tank and a substantial amount of hot water is provided. 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.

  In an instant hot water heater for a shower toilet, in order to heat the water in the water supply pipe into hot water, a resistance-type electric heater that generates Joule heat is often provided. In addition, in order to supply warm water with a comfortable water temperature and flow rate and improve user convenience, a water temperature sensor and a flow meter are provided, and a control unit that performs appropriate control from the detected water temperature and flow rate information is provided. Is also commonly done. However, providing the sensors complicates the device configuration and increases the cost. Therefore, measures for improving the control function while simplifying the device have been studied. For example, the toilet apparatus disclosed in Patent Literature 1 and Patent Literature 2 includes instantaneous heating means, control means, and the like, and achieves cost reduction by obtaining a flow rate by estimation without using a flow meter.

Furthermore, Patent Document 1 includes a power supply voltage detection unit that detects a change in power supply voltage and manages the amount of heat generated by the heater with high accuracy. As another method of managing the heat generation amount, there may be a case where a stabilized power source that stabilizes the power source voltage is provided.
JP 2003-247262 A JP 2004-263423 A

  By the way, in the flow estimation and temperature control of the control part in patent document 1 and patent document 2, the heat capacity of the heated part, the passage time of water from the heated part to the temperature detection part, the detection time delay of the sensor, estimation and control There is a possibility that sufficiently accurate control cannot be performed in a transient state due to unclear timing. That is, even if good control can be performed in a steady state where the temperature and flow rate of each part is stable, it is difficult to perform appropriate control in a transient state immediately after the start of operation or immediately after the setting of temperature or flow rate is changed. On the other hand, the power source voltage detection means or the stabilized power source required for managing the heat generation amount is a factor that increases the cost and is an obstacle to space saving.

  The present invention has been made in view of the above background, and even with a simple configuration that does not use a voltmeter or a flow meter, the temperature and flow rate of hot water to be supplied can be managed with high accuracy, and space-saving and low-cost electric heating An instant water heater and a control method thereof are provided.

  An electric heating instantaneous water heater control method according to the present invention includes a water supply pipe for supplying water, a flow rate adjusting valve disposed in the middle of the water supply pipe, a water temperature sensor for detecting water temperature, and Joule heat in the water. A heating unit that is arranged in the middle of the water supply pipe, a setting unit that sets a desired target water temperature and a target flow rate, an input unit that takes in the detected water temperature of the water temperature sensor, and an internal calculation A control method of an electric heating instantaneous water heater comprising a calculation unit to perform and a control device comprising an output unit for controlling the flow rate adjustment valve and the electric heater, wherein the flow rate adjustment valve is closed and the electric heater A voltage calculation step of calculating a power supply voltage from the heat capacity and water temperature rise value of the heating unit and the amount of heat radiation to the outside when heated for a period of time during which the heating water is heated, and the detected water temperature is calculated based on the calculated power supply voltage. At the target water temperature A hydrostatic heating step for controlling the electric heater so that the electric heater is heated, and when the electric heater is heated for a predetermined flowing water heating time by opening the flow rate adjustment valve so as to match the target flow rate, the heat capacity and the water temperature rise value of the heating unit And a voltage recalculation step for recalculating the power supply voltage from the heat radiation amount to the outside and the target flow rate, and the electric heater to adjust the detected water temperature to the target water temperature based on the recalculated power supply voltage. And a running water heating step to be controlled.

  The control method for the electric heating instantaneous water heater according to the present invention is characterized in that the calculation is performed by the calculation means on the software of the control device without providing a voltmeter or a flow meter for detecting the power supply voltage or the flow rate. In particular, the power supply voltage can be calculated at any time in a still water state where water does not flow and a flowing water state where water flows, thereby improving accuracy.

  First, the configuration of the electric heating instantaneous water heater will be described. The water supply pipe is a part that is connected to a water supply source and supplies water. The flow rate adjusting valve is disposed in the middle of the water supply pipeline, and is a portion that adjusts the flow rate of water by opening and closing the pipeline and adjusting the opening. The flow rate adjustment valve can be controlled from a control device, and for example, an electromagnetic valve can be applied. A heating unit is further provided in the middle of the water supply pipeline. The heating unit includes a water temperature sensor that detects the water temperature and an electric heater that adds Joule heat to the water. The electric heater is a resistor that generates Joule heat. For example, the electric heater can be disposed so as to be wound around a water supply pipe and to heat water through the pipe wall. Or you may make it heat water indirectly via a heat exchanger. The water temperature sensor detects the temperature of still water or running water in the water supply pipe, and the temperature sensing part is preferably provided in the water supply pipe. In order to avoid a time delay in detecting the water temperature, it is preferable that the heat capacity of the temperature sensing unit itself is small.

  The control device includes a setting unit, an input unit, a calculation unit, and an output unit. For example, an electronic control device to which a microcomputer is applied can be used to control with built-in software. A setting part is a site | part which sets the target flow volume and target water temperature which a user desires. An input part is a site | part which takes in the detection water temperature of a water temperature sensor with the form of an electrical signal. The calculation unit is a part that performs an internal calculation based on built-in software or a constant table. The output unit is a part that outputs a control signal to the flow rate adjusting valve and the electric heater based on the instruction of the software and the result of the internal calculation.

  Next, a control method of the electric heating instantaneous water heater configured as described above will be described. The control method of the present invention comprises four steps: a voltage calculation step, a still water heating step, a voltage recalculation step, and a running water heating step.

  In the voltage calculation step, the control device closes the flow rate adjustment valve to bring the water to a stationary state, energizes the electric heater, and heats it for a predetermined hydrostatic heating time. Here, it is possible to consider a calorie balance equation in which the effective amount of heat obtained by subtracting the amount of heat released to the outside from the total amount of Joule heat added contributes to an increase in the water temperature of the heating unit. First, the equation when the unit time has elapsed from the time t = 0 when heating is started is given by Equation 1. Here, R is the resistance value of the electric heater, V is the power supply voltage, u is the voltage reduction rate, L is the amount of heat released to the outside, C is the heat capacity of the heating unit, and T (t) is the detected water temperature at time t. Show. The power supply voltage V is an amount that is unknown but may be considered constant in a short time span in which voltage calculation is performed. The voltage reduction rate u means a ratio for reducing the effective voltage value supplied to the electric heater. The voltage reduction rate u is a temporally variable control amount set by the control device itself. The amount of heat radiation L to the outside depends on the structure of the water heater, but can be ignored when it has good heat insulation. If it cannot be ignored, the heat release amount L may be obtained experimentally and expressed as a function of Joule heat, for example. As the function form, for example, a constant ratio of Joule heat can be used, or a function of second order or higher can be used. The heat capacity C of the heating unit takes into account not only water but also components such as the water supply pipe itself. The numerical values of the heat radiation amount L to the outside and the heat capacity C of the heating unit can be stored in advance in the control device as a constant table or an arithmetic expression. The detected water temperature T (t) is an amount actually measured by the water temperature sensor. Since the volume specific heat of water is 1, it is omitted in the formula.

  Next, considering the heating over the hydrostatic heating time ts, the heat balance is given by Equation 2 which is the integral form of Equation 1. The hydrostatic heating time ts and the voltage reduction rate u described above can be set arbitrarily, but the water temperature of the heating unit does not reach the target water temperature and the power supply voltage V can be accurately calculated. It is preferable. Here, since the amount other than the power supply voltage V is a known amount, the power supply voltage V can be calculated. The voltage calculation step can be optionally performed during an arbitrary time period when hot water is not supplied.

  In the still water heating step, the electric heater is controlled so that the detected water temperature matches the target water temperature based on the calculated power supply voltage. That is, the electric heater generates the total amount of heat obtained by multiplying the temperature difference between the target water temperature and the detected water temperature by the heat capacity C and adding the heat radiation amount L. At this time, it is preferable to perform feedback control in order to reach a steady state in as short a time as possible. That is, it is preferable that the heat generation amount of the electric heater is initially increased, and control is performed so that the heat generation amount is reduced as the detected water temperature approaches the target water temperature.

  When the detected water temperature matches the target water temperature, preparation for hot water supply is completed. Here, when a hot water supply instruction is received, the voltage recalculation step of the control device functions.

  In the voltage recalculation step, the control device opens the flow rate adjustment valve so as to match the target flow rate so that water flows, energizes the electric heater and heats it for a predetermined flowing water heating time. Then, the power supply voltage V is calculated again. In the calculation, it is necessary to consider heat transport by flowing water in addition to Equation 2, and the equation of heat balance is replaced by Equation 3. Here, A represents the flow rate per unit time, and ΔT represents the temperature rise in the heating part of the passing water. The flow rate A is a target flow rate A0 set by adjusting the opening of the flow rate adjustment valve. The temperature rise ΔT can be obtained from, for example, a difference in detected water temperature by providing water temperature sensors at the inlet and outlet of the heating unit. Here, since the amount other than the power supply voltage V is a known amount, the power supply voltage V can be calculated again. The voltage recalculation step is preferably performed at the start of hot water supply.

  In the flowing water heating step, the electric heater is controlled so that the detected water temperature matches the target water temperature based on the power supply voltage calculated again. Again, it is preferable to perform feedback control to suppress deviation from the target water temperature of the supplied hot water. In addition, during implementation of a flowing water heating step, a voltage recalculation step can also be performed at any time.

  The electric heating instantaneous water heater is used in a shower toilet and includes a seating detection sensor and a washing instruction switch. When the user's seating is detected, the voltage calculation step and the still water heating step are performed, and the washing instruction switch Preferably, the voltage recalculation step and the flowing water heating step are performed when turned on.

  The electric hot water heater of the present invention can be applied to a shower toilet, and preferably includes a seating detection sensor and a cleaning instruction switch. And when a user's seating is detected, it is preferable to implement a voltage calculation step and a still water heating step. Thereby, the water in the heating unit is heated to the target water temperature in a short time and enters a standby state. Next, it is preferable to perform a voltage recalculation step and a flowing water heating step when the cleaning instruction switch is turned on. As a result, the desired target flow rate and hot water at the target water temperature are supplied without delay.

  In addition, there may be a case where the target flow rate and the target water temperature are set and changed during the hot water supply by performing the flowing water heating step. At this time, the flow rate adjusting valve may be closed once and the voltage calculation step may be performed again, or the voltage recalculation step and the running water heating step are performed again while continuously changing the control of the flow rate adjustment valve and the electric heater. You may do it.

Any The coolant temperature sensor is inlet water temperature sensor and an outlet water temperature sensor for detecting respectively the inlet water temperature and outlet water temperature of the heating portion, the inlet water temperature, the mean value of the outlet water temperature and the inlet coolant temperature and the outlet water temperature, the It is preferable that the water temperature of the heating unit is set.

  The water temperature sensor that detects the water temperature of the heating unit needs two functions. The first function is to detect the temperature change of the heating unit itself, and the second function is to detect the temperature rise of the passing water. In order to achieve the second function, it is necessary to detect the inlet water temperature and the outlet water temperature of the heating unit, and the arrangement of the sensors is inevitably determined. On the other hand, in order to achieve the first function, it is preferable to detect the average temperature of the heating unit. When the electric heater has a structure that heats the inside of the heating part uniformly, the inside of the heating part in the still water state is immediately isothermal, but if there is a temperature difference between the inlet and the outlet in the transient state, the average temperature of the heating part is entered. It is appropriate to set the average value of the water temperature and the outlet water temperature. In the flowing water state, it is appropriate to set this average value as the average temperature of the heating section. Of course, in order to obtain the average temperature of the heating unit, a third water temperature sensor may be provided at a location exhibiting an average temperature near the center. When uniform heating cannot be expected due to structural constraints, the temperature distribution in the heating section becomes complicated. Therefore, it is difficult to represent the average temperature by the inlet water temperature or the outlet water temperature. At this time, it is preferable to obtain an average temperature of the heating unit by performing some correction on the detected water temperature using an experimental method. At this time, even if the correction is complicated, the arithmetic unit of the control device can automatically perform the correction by using a constant table or an arithmetic expression.

And said power supply voltage calculated again by the voltage re calculation step, said having said heat capacity and the temperature rise value of the heating unit, the amount of heat released to the outside, the flow rate confirmation step of calculating the actual flow rate from it preferable.

  At an arbitrary time after calculating the power supply voltage V using Equation 3 in the voltage recalculation step, the actual flow rate A1 is obtained by substituting the calculated power supply voltage V, considering the flow rate A of Equation 3 as an unknown. be able to. Through this flow rate confirmation step, it is possible to confirm whether the actual flow rate A1 matches the target flow rate A0 and whether the actual flow rate A1 has changed over time.

  It is preferable that the effective value of the voltage supplied to the electric heater is controlled in the still water heating step and the flowing water heating step. Further, the resistance value of the electric heater may be controlled in the still water heating step and the flowing water heating step.

  As the control of the electric heater performed by the control unit, it is preferable to control the effective value of the supplied voltage, and the change of the voltage reduction rate u corresponding to the control of the voltage reduction rate u described above is performed by, for example, energization phase control. This is realized by controlling the energization time range in one cycle of AC voltage. Or you may make it provide the transformation function of variable transformation ratio. Alternatively, the resistance value of the electric heater may be controlled. For example, if the electric heater is formed of a plurality of resistors, the resistance value can be changed by appropriately changing the connection. A sliding variable resistor may be used. Of course, both the supplied voltage and the resistance value may be variably controlled. In any method, the Joule heat generation amount of the electric heater can be variably controlled.

  The instant electric water heater of the present invention includes a water supply pipe for supplying water, a flow rate adjusting valve disposed in the middle of the water supply pipe, a water temperature sensor for detecting water temperature, and electric heat for adding Joule heat to the water. A heating unit comprising a heater and disposed in the middle of the water supply pipeline, a setting unit for setting a desired target flow rate and a target water temperature, an input unit for taking in the detected water temperature of the water temperature sensor, and a calculation unit for performing internal calculations And an electric heating instantaneous water heater comprising an output unit for controlling the flow rate adjusting valve and the electric heater, wherein the control device closes the flow rate adjusting valve and performs predetermined static water with the electric heater. When heated for a heating time, voltage calculation means for calculating a power supply voltage from the heat capacity and water temperature rise value of the heating unit and the amount of heat radiation to the outside, and the detected water temperature based on the calculated power supply voltage Match the target water temperature And a hydrostatic heating means for controlling the electric heater, and when the electric heater is heated for a predetermined flowing water heating time by opening the flow rate adjusting valve so as to match the target flow rate, the heat capacity and water temperature rise value of the heating unit and the external Voltage recalculation means for recalculating the power supply voltage from the heat dissipation amount and the target flow rate, and controlling the electric heater so that the detected water temperature matches the target water temperature based on the recalculated power supply voltage And running water heating means.

  The four steps constituting the control method of the present invention can be realized by means of software of the control device, and thus can be realized as an electric heating instantaneous water heater. Since the electric heating instantaneous water heater of the present invention does not require a voltmeter or a flow meter, it can save space and be low in cost.

  According to the control method for the electric heating instantaneous water heater and the above-described present invention, the power supply voltage is calculated in the voltage calculation step and the voltage recalculation step. Can manage the flow rate with high accuracy. Furthermore, since a voltmeter and a flow meter are not required, it is possible to provide an electric heating instantaneous water heater that is space-saving and low-cost.

  The best mode for carrying out the present invention will be described with reference to FIGS. FIG. 1 is a diagram illustrating an electric heating instantaneous water heater according to an embodiment of the present invention. The electric heating instantaneous water heater 1 of the embodiment is used by being incorporated in a shower toilet, and is composed of a water supply pipe line 2, a flow rate adjusting valve 3, a heating unit 4, and a control device 5.

  The water supply pipe 2 is a part that is connected to a water supply source (not shown) and supplies water. In the middle of the water supply pipe, a heating unit 4 and a flow rate adjusting valve 3 are arranged from the water supply source side. As will be described later, an electromagnetic valve is used as the flow rate adjusting valve 3 and is controlled by the output unit 54 of the control unit 5 to adjust the flow rate of water by opening and closing the feed water pipe 2 and adjusting the opening degree. It is like that.

  The heating unit 4 includes a ceramic heater 41, an inlet water temperature sensor 45, and an outlet temperature sensor 46. The ceramic heater 41 is a resistor that generates Joule heat, and is disposed on the outer peripheral surface of the water supply pipeline. Further, a thermal fuse 411 is attached to the ceramic heater 41 so as to cut off the current IH when the water temperature rises. The ceramic heater 41 is connected to the voltage adjusting unit 55 of the control unit 5 by a power line 412. In the inlet water temperature sensor 45, a temperature sensing unit 451 is disposed inside the water supply pipe 2 near the upstream side of the ceramic heater 41, and the output line 452 is connected to the input unit 52 of the control unit 5. In the outlet water temperature sensor 46, a temperature sensing unit 461 is disposed inside the water supply pipe 2 near the downstream side of the ceramic heater 41, and the output line 462 is connected to the input unit 52 of the control unit 5. The inlet water temperature sensor 45 and the outlet water temperature sensor 46 detect the water temperature in the water supply pipe 2.

  The control device 5 includes a setting unit 51, an input unit 52, a calculation unit 53, an output unit 54, and a voltage adjustment unit 55, and is configured by an electronic control device to which a microcomputer is applied. The setting unit 51 includes a water temperature setting switch 511 for setting the target water temperature T0, a flow rate setting switch 512 for setting the target flow rate A0, a washing instruction switch 513 for instructing the supply of hot water, and a seating detection sensor for detecting the seating state on the toilet seat 91. 514. The water temperature setting switch 511 and the flow rate setting switch 512 are variable, and a user can select and set desired values. The cleaning instruction switch 513 can be turned on and off by the user. The seating detection sensor 514 automatically detects the user's seating and unseating. These pieces of information are configured to be transmitted to the calculation unit 53. The input unit 52 is configured to take in the detected water temperatures of the inlet water temperature sensor 51 and the outlet water temperature sensor 46 in the form of an electrical signal and transmit them to the calculation unit 53.

  The calculation unit 53 is a part that performs internal calculations of Formulas 1 to 3 based on built-in software and a constant table. Naturally, necessary information is fetched from the setting unit 51 and the input unit 52 prior to the internal calculation. Based on the calculation result, the control signal is transmitted to the output unit 54. The output unit 54 is configured to output a control signal instructing the opening degree to the flow rate adjusting valve 3 and to control the voltage adjusting unit 55 in accordance with a control signal from the calculation unit 53.

  The voltage adjustment unit 55 is configured to receive a general household AC power supply 92 as an input, control the voltage reduction rate u according to the control of the output unit 54, and then supply power to the ceramic heater 41. The voltage reduction rate u is changed by variably controlling the energization phase range in one cycle of AC voltage, and the effective voltage value VH supplied to the electric heater 41 is adjusted. The control unit 5 itself is also configured to be driven by an AC power source 92, and the operation power for the water temperature sensors 45 and 46 is supplied from the control unit 5.

  Next, the operation procedure and control method of the electric heating instantaneous water heater 1 of the embodiment of FIG. 1 will be described with reference to FIG. FIG. 2 is an operation flowchart for explaining the operation of the electric heating instantaneous water heater 1 of the embodiment, and item numbers with parentheses in the figure are described correspondingly in the following description.

  First, the target water temperature T0 and the target flow rate A0 are set by the user in the setting unit 51 of the control device 5 (1). The set value can be changed at any time, and the calculation unit 53 always knows the set value. The control device 5 always pays attention to the detection state of the seating detection sensor 514 in the seating standby state (2). When the user sits on the toilet seat 91 and the seating detection sensor 514 detects the seating state, the voltage calculation step (3) is executed, and the power supply voltage V of the AC power supply 92 is calculated using Equation 2. Subsequently, the still water heating step (4) is performed, and heating is performed until the detected temperature reaches the target temperature T0. When the heating is finished, preparation for hot water supply is completed, and a standby state is waited for a cleaning instruction.

  In the cleaning instruction standby state (5), attention is paid to the detection state of the seating detection sensor 514 and the cleaning instruction switch 513. Here, when the user leaves the seat, that is, away from the toilet seat, the seating detection sensor 514 detects the seating and returns to the seating standby state (2). That is, it means that the user has left the toilet without using hot water and waits for the next use opportunity. When the user has just floated from the toilet seat 91, the seating is detected again in the seating standby state (2) and returns to the cleaning instruction standby state (5) in a short time. The same standby state (5) is maintained while the cleaning instruction switch 513 is not operated while sitting in the cleaning instruction standby state (5). When the cleaning instruction switch 513 is turned on in the seated state, the voltage recalculation step (6) is executed, and the power supply voltage V of the AC power supply 92 is calculated again using Equation 3. Subsequently, a running water heating step (7) is executed to supply hot water having a target temperature T0.

  Subsequently, the flow rate confirmation step (8) is executed, and the actual flow rate A1 is confirmed using Equation 3. This flow rate confirmation step (8) is not essential and may be omitted or may be performed intermittently at a certain frequency. In the next end standby state (9), attention is paid to the detection state of the seating detection sensor 514 and the washing instruction switch 513 in parallel with the supply of hot water. Here, when the user leaves the seat, that is, away from the toilet seat, the seating detection sensor 514 detects the seating and returns to the seating standby state (2). In other words, it means that the user has left the toilet and waits for the next use opportunity. While the washing instruction switch 513 is not operated while sitting in the end standby state, the supply of warm water by the running water heating step (7) is continued. When the cleaning instruction switch 513 is turned off in the sitting state, it is determined that the end of cleaning is instructed, and the process returns to the cleaning instruction standby state (5). Here, if the washing instruction switch 513 is turned on again, the voltage recalculation step (6) and the running water heating step are executed, hot water is supplied again, and if it is removed, the seating standby state (2) is restored.

  Next, the concept of the heat balance will be described with reference to FIG. FIG. 3 is a diagram schematically illustrating the heat flow in the electric heating instantaneous water heater 1 of the embodiment. As shown in the figure, electric energy is supplied from an AC power source 92, reduced by the voltage control unit 55, and converted into thermal energy by the ceramic heater 41. Thermal energy is consumed by heating the warm water, increasing the temperature of the heating unit 4, and the amount of heat radiation L to the outside. The width of the hatched band in the figure indicates the approximate amount of heat. As shown in the figure, the power supply voltage V of the AC power supply 92 is multiplied by the voltage reduction rate u by the voltage adjustment unit 55, and the supply voltage VH having an effective value uV is supplied to the ceramic heater 41. As a result, in the ceramic heater 41 having the resistance value R, the electric energy is converted into a heat quantity Q of Joule heat. A part of the heat quantity Q is not used but becomes a heat release amount L to the outside, and the remaining effective heat quantity is used for heating the hot water and increasing the temperature of the heating unit 4 itself. The amount of heat used for heating the hot water is represented by the product of the water flow rate A0, the volume specific heat (= 1), and the temperature rise ΔT. The amount of heat used to increase the temperature of the heating unit 4 itself is represented by the product of the heat capacity C of the heating unit and the temperature increase.

  A mathematical expression expressing the above description with a mathematical expression is Numerical Expression 3, and a mathematical expression with the flow rate A0 = 0 in Numerical Expression 3 is Numerical Expression 2. Since the ceramic heater heats the inside of the heating unit 4 substantially uniformly, the detected water temperature of the outlet temperature sensor 46 can be used as the temperature T (t) of the heating unit in Equation 2. Further, the water temperature increase ΔT in Formula 3 can be obtained by subtracting the detected water temperature of the inlet temperature sensor 45 from the detected water temperature of the outlet temperature sensor 46.

  As described above, according to the electric heating instantaneous water heater 1 of the embodiment, the control method of the present invention can be executed. The electric heating instantaneous water heater 1 of the embodiment does not require an ammeter or a flow meter, and is space-saving and low-cost.

It is a figure explaining the electric heating type instant water heater incorporated in the shower toilet in the Example of this invention. It is an operation | movement flowchart explaining operation | movement of the electric heating type instantaneous water heater of the Example of FIG. It is a figure which illustrates typically the calorie | heat amount flow in the electric heating type instantaneous water heater of the Example of FIG.

Explanation of symbols

1: Electric heating type instantaneous water heater 2: Water supply line 3: Flow rate adjusting valve 4: Heating unit
41: Ceramic heater 45: Inlet water temperature sensor 46: Outlet temperature sensor 5: Control unit
51: Setting unit 52: Input unit 53: Calculation unit
54: Output unit 55: Voltage adjustment unit 91: Toilet seat 92: AC power supply V: Power supply voltage u: Voltage reduction rate VH: Supply voltage (= uV)
R: Resistance value of the electric heater (ceramic heater) L: Heat radiation to the outside C: Heat capacity of the heating part T0: Target water temperature A0: Target flow rate T (t): Detected water temperature at time t A1: Actual flow rate

Claims (7)

A water supply pipe for supplying water, a flow rate adjusting valve arranged in the middle of the water supply pipe, a water temperature sensor for detecting the water temperature, and an electric heater for adding Joule heat to the water are provided in the middle of the water supply pipe. A heating unit, a setting unit for setting a desired target flow rate and a target water temperature, an input unit for taking in the detected water temperature of the water temperature sensor, a calculation unit for performing an internal calculation, the flow rate adjusting valve, and the electric heater, A control device comprising an output unit for controlling the electric heating instantaneous water heater comprising:
Voltage calculation step of calculating a power supply voltage from the heat capacity and water temperature rise value of the heating unit and the amount of heat radiation to the outside when the flow rate adjustment valve is closed and heated by the electric heater for a predetermined hydrostatic heating time,
A hydrostatic heating step of controlling the electric heater so that the detected water temperature matches the target water temperature based on the calculated power supply voltage;
When the flow rate adjustment valve is opened so as to match the target flow rate and heated by the electric heater for a predetermined flowing water heating time, the power supply voltage is calculated from the heat capacity and water temperature rise value of the heating unit, the heat radiation amount to the outside, and the target flow rate. A voltage recalculation step to calculate again,
A flowing water heating step of controlling the electric heater so that the detected water temperature matches the target water temperature based on the power supply voltage calculated again;
A control method for an electric heating type instantaneous water heater.   The electric heating instantaneous water heater is used in a shower toilet and includes a seating detection sensor and a washing instruction switch. When the user's seating is detected, the voltage calculation step and the still water heating step are performed, and the washing instruction switch The method for controlling an electric heating instantaneous water heater according to claim 1, wherein the voltage recalculation step and the flowing water heating step are performed when turned on. Any The coolant temperature sensor is inlet water temperature sensor and an outlet water temperature sensor for detecting respectively the inlet water temperature and outlet water temperature of the heating portion, the inlet water temperature, the mean value of the outlet water temperature and the inlet coolant temperature and the outlet water temperature, the The method for controlling an electric heating instantaneous water heater according to claim 1 or 2, wherein the water temperature of the heating unit is used. The flow rate confirmation step of calculating an actual flow rate from the power supply voltage recalculated in the voltage recalculation step, the heat capacity and the water temperature rise value of the heating unit, and the heat radiation amount to the outside. The control method of the electric heating type instantaneous water heater as described in any one of -3. The control method of the electric-heat-type instantaneous water heater as described in any one of Claims 1-4 which controls the effective value of the voltage provided to the said electric heater by the said static water heating step and the said flowing water heating step. The control method of the electric-heat-type instantaneous water heater as described in any one of Claims 1-4 which controls the resistance value of the said electric heater in the said static water heating step and the said flowing water heating step. A water supply pipe for supplying water, a flow rate adjusting valve arranged in the middle of the water supply pipe, a water temperature sensor for detecting the water temperature, and an electric heater for adding Joule heat to the water are provided in the middle of the water supply pipe. A heating unit, a setting unit for setting a desired target flow rate and a target water temperature, an input unit for taking in the detected water temperature of the water temperature sensor, a calculation unit for performing an internal calculation, the flow rate adjusting valve, and the electric heater, An electric heating instantaneous water heater comprising a control device comprising an output unit for controlling
The controller is
When the flow rate adjusting valve is closed and heated by the electric heater for a predetermined hydrostatic heating time, voltage calculation means for calculating a power supply voltage from the heat capacity and water temperature rise value of the heating unit and the amount of heat radiation to the outside,
Hydrostatic heating means for controlling the electric heater so that the detected water temperature matches the target water temperature based on the calculated power supply voltage;
When the flow rate adjustment valve is opened so as to match the target flow rate and heated by the electric heater for a predetermined flowing water heating time, the power supply voltage is calculated from the heat capacity and water temperature rise value of the heating unit, the heat radiation amount to the outside, and the target flow rate. Voltage recalculation means to calculate again,
Flowing water heating means for controlling the electric heater so that the detected water temperature matches the target water temperature based on the power supply voltage calculated again;
An electric heating instantaneous water heater characterized by having.

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