Water heater

Abstract

To make a frequency of rotating position initialization processing of a stepping motor appropriate in a water heater in which a valve of which opening is controlled by using the stepping motor as a drive source is disposed.SOLUTION: A controller 10 executes position reset of a stepping motor 150 serving as a drive source of a valve 90 on the basis of a comparison between an operation parameter of a water heater and a determination value. During execution of the position reset, in the case where a control value of a rotating position MPc is initialized in accordance with a detection signal LS generated when the rotating position MPc reaches a reference position, if a magnitude of an error between the control value and the reference position before the initialization is larger than a reference range, the determination value is changed so that the execution frequency of the position reset increases.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a hot water supply apparatus, and more particularly to a hot water supply apparatus including a valve whose opening degree is controlled by being driven by a stepping motor.

Background Art

[0002] Japanese Patent No. 4090413 (Patent Document 1) describes a configuration in a combined hot water supply system using a plurality of hot water heaters connected in parallel, where each hot water heater has a flow rate adjustment valve driven by a stepping motor (pulse motor) as a drive source. Since the rotational position (angle) of the stepping motor changes in an open loop manner in response to the input of digital pulses, it is advantageous in terms of cost including ease of control.

[0003] In Patent Document 1, the hot water flow rate from each hot water heater is controlled by the opening degree of each flow rate adjustment valve. Further, Patent Document 1 describes that a position reset (rotation position initialization process) is executed for each flow rate adjustment valve to eliminate the position deviation (detuning) of the stepping motor. By periodically executing the position reset, it is possible to suppress the error between the actual valve opening degree and the valve opening degree recognized by the control unit due to the deviation of the rotational position of the stepping motor.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] As also described in Patent Document 1, in the position reset, the state in which a pulse signal is applied to the stepping motor to change the valve opening degree continues until a hard detection signal generated when the valve opening degree reaches the reference opening degree is received.

[0006] Therefore, if the frequency of position reset is too low, there is a concern about the above-described valve opening error. On the other hand, if the frequency is too high, there is a concern that problems such as an increase in power consumption of the stepping motor and a decrease in equipment durability may occur.

[0007] The present invention has been made to solve such problems, and an object of the present invention is to appropriately execute a rotation position initialization process of a stepping motor in a hot water supply apparatus in which a valve whose opening degree is controlled using the stepping motor as a drive source is arranged.

Means for Solving the Problems

[0008] In one aspect of the present invention, a hot water supply apparatus is provided. The hot water supply apparatus includes a control valve and a controller. The control valve is arranged in a fluid flow path and has its opening degree controlled using a stepping motor as a drive source. The controller controls the rotational position of the stepping motor in order to control the opening degree of the control valve. The stepping motor is configured to output a detection signal to the controller when the rotational position reaches a predetermined reference position. The controller executes a rotation position initialization process by continuously generating a control signal for driving the rotational position of the stepping motor to the reference position based on a comparison between an operation parameter of the hot water supply apparatus and a determination value until the detection signal is received from the stepping motor. Further, when executing the rotation position initialization process, the controller initializes the control value of the rotational position to a value corresponding to the reference position when the detection signal is received, and changes the determination value so that the execution frequency of the rotation position initialization process increases when the absolute value of the error between the control value before initialization and the reference position is larger than a predetermined reference range.

Effects of the Invention

[0009] According to the present invention, in a hot water supply apparatus in which a valve whose opening degree is controlled using a stepping motor as a drive source is arranged, the rotation position initialization process of the stepping motor can be executed at an appropriate frequency.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

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Figure 4

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Figure 7

Figure 8

Mode for Carrying Out the Invention

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following, the same or corresponding parts in the drawings are denoted by the same reference numerals, and the description thereof will not be repeated in principle.

[0012] FIG. 1 is a block diagram for explaining the configuration of the water heater 1A according to the present embodiment. Referring to FIG. 1, the water heater 1A has a water inlet port 11 connected to the water inlet pipe 110, a hot water outlet port 12 connected to the hot water outlet pipe 120, and a circulation port 13 connected to the circulation pipe 130. Further, the water heater 1A includes a controller 10, a water inlet path 20, a check valve 21, a bypass path 22, a circulation path 23, a hot water outlet path 25, a combustion mechanism 30, a heat exchanger 40, a circulation pump 80, and a flow rate adjustment valve 90, which are stored in the housing 100.

[0013] The water inlet path 20 is formed between the water inlet port 11 and the input side (upstream side) of the heat exchanger 40 via a check valve 21. The combustion mechanism 30 is typically composed of a burner that generates heat by burning gas, oil, or the like. The heat exchanger 40 uses the amount of heat generated by the combustion mechanism 30 to heat the low-temperature water (fluid) introduced through the water inlet path 20 and raise its temperature. The combustion mechanism 30 and the heat exchanger 40 constitute an embodiment of the "heating mechanism".

[0014] The hot water outlet path 25 is formed between the output side (downstream side) of the heat exchanger 40 and the hot water outlet port 12. The bypass path 22 connects between the water inlet path 20 and the hot water outlet path 25 without passing through the heat exchanger 40. The bypass path 22 is arranged to connect a site downstream of the connection point 27 with the circulation path 23 on the upstream side (input side) of the heat exchanger 40 (in FIG. 1, the location where the flow rate adjustment valve 90 is arranged) and a site upstream of the connection point 125 on the downstream side (output side) of the heat exchanger 40 (connection point 26). By controlling the opening degree of the flow rate adjustment valve 90 by the controller 10, the ratio of the flow rate of the heat exchanger 40 to the flow rate of the bypass path 22 is adjusted. In this way, at least a part of the fluid flowing through the flow rate adjustment valve 90 is heated by the heat exchanger 40 (heating mechanism).

[0015] A temperature detector 71 is arranged in the water inlet path 20. The temperature detector 71 detects the water inlet temperature Tw before heating by the heat exchanger 40. In contrast, temperature detectors 72 and 73 are arranged in the hot water outlet path 25. The temperature detector 72 is arranged downstream of the connection point 26 with the bypass path 22 in the hot water outlet path 25 to detect the hot water outlet temperature Th. On the other hand, the temperature detector 73 is arranged upstream of the connection point 26 to detect the can body temperature Tb corresponding to the output temperature from the heat exchanger 40. Each fluid temperature detected by the temperature detectors 71 to 73 is input to the controller 10.

[0016] Furthermore, a flow rate detector 75 is provided in the water heater 1A. For example, the flow rate detector 75 is disposed downstream of a flow rate adjustment valve 90 located at a connection point 27 with the circulation path 23 and a branch point with the bypass path 22 in the water inlet path 20 so as to detect the flow rate (the can body flow rate) to be heated by the heat exchanger 40. The flow rate detection value Qf by the flow rate detector 75 is input to the controller 10.

[0017] When the hot water faucet 200 is opened and the hot water supply destination starts hot water supply, cold water is introduced into the water inlet path 20 by the supply pressure of the cold water. Accordingly, when a flow rate exceeding the minimum operating flow rate (MOQ) is detected by the flow rate detector 75 while the operation switch of the water heater 1A is on, the controller 10 turns on the combustion mechanism 30 to start the hot water supply operation. Note that the hot water faucet 200 is an example representative of the "hot water supply destination" of the water heater 1A. The hot water supply destination may include a solenoid valve for turning on and off the hot water output to a bathtub or the like, and is not limited to a device directly opened and closed by a user operation. When the hot water faucet 200 is closed and the hot water supply destination stops hot water supply, cold water is no longer introduced into the water inlet path 20. Accordingly, as the detection value of the flow rate detector 75 drops below the minimum operating flow rate (MOQ), the controller 10 turns off the combustion mechanism 30 to end the hot water supply operation.

[0018] During the hot water supply operation, the high-temperature water heated by the combustion mechanism 30 and the heat exchanger 40 is mixed with the cold water passing through the bypass path 22 and then output from the hot water outlet port 12 to the hot water faucet 200 via the hot water outlet pipe 120. During normal hot water supply operation, the controller 10 stops the circulation pump 80 and controls the fluid temperature (the hot water outlet temperature Th) detected by the temperature detector 72 to the hot water supply set temperature Tr input to a remote controller (not shown). The controller 10 corresponding to an embodiment of the "controller" is typically configured as a microcomputer.

[0019] In the water supply device 1A, since a part of the cold water bypasses the heat exchanger 40 and remains unheated, and is mixed downstream of the heat exchanger 40, warm water at an appropriate temperature is supplied from the hot water outlet port 12. Therefore, the output temperature (cylinder temperature) from the heat exchanger 40 (heating mechanism) can be made higher than the hot water supply set temperature Tr. As a result, it is possible to suppress the drain generated when the exhaust gas of the combustion mechanism 30 is cooled on the surface of the heat exchanger 40.

[0020] The controller 10 can perform hot water temperature control by combining the control of the heating amount (generated heat amount) by the combustion mechanism 30 and the control of the bypass flow rate ratio by the flow rate adjustment valve 90.

[0021] In the water supply device 1A, when the hot water supply operation is stopped due to the closing of the hot water tap 200 or the like, the temperature of the fluid remaining in the hot water path 25 and the hot water pipe 120 decreases. Therefore, there is a concern that it will take time to supply hot water at an appropriate temperature to the hot water tap 200 after the start of the next hot water supply operation. For this reason, the water supply device 1A is provided with an instant hot water operation function for quickly supplying high-temperature water after the start of the hot water supply operation by arranging the circulation port 13, the circulation path 23, and the circulation pump 80.

[0022] The circulation path 23 is formed between the circulation port 13 and the water inlet path 20 (connection point 27). The circulation pump 80 is inserted and connected to the circulation path 23. Alternatively, the circulation pump 80 may be inserted and connected to the circulation pipe 130 outside the housing 100. The operation and stop of the circulation pump 80 are controlled by the controller 10.

[0023] For example, the instant hot water operation can be started when the instant hot water operation mode is turned on by a switch operation or a timer setting, there is no hot water supply use, and the fluid temperature (for example, the cylinder temperature Tb and / or the hot water temperature Th detected by the temperature detectors 72, 73) drops below the instant hot water start determination temperature (for example, set a predetermined temperature lower than the hot water supply set temperature).

[0024] The instant hot water operation is realized by forming an instant hot water circulation path including a heat exchanger 40 (heating mechanism) by the operation of a circulation pump 80 while the supply of hot water from the above-described hot water faucet 200, etc. is stopped. The instant hot water circulation path is formed by a loop that returns from a circulation port 13, through a circulation path 23, a water inlet path 20 (downstream of a connection point 27), the heat exchanger 40, a hot water outlet path 25, a hot water outlet port 12, and a hot water outlet pipe 120 (upstream of a connection point 125), and a circulation pipe 130, back to the circulation port 13.

[0025] When the above instant hot water circulation path is formed by the operation of the circulation pump 80, the combustion mechanism 30 operates when the flow rate detection value Qf of the flow rate detector 75 exceeds the MOQ. Thereby, the hot water in the instant hot water circulation path is heated. The instant hot water operation ends when the fluid temperature in the instant hot water circulation path (for example, the water inlet temperature Tw or the hot water outlet temperature Th detected by the temperature detector 71 or 72) reaches the instant hot water end determination temperature (for example, the hot water supply set temperature), and the heating by the combustion mechanism 30 is stopped and the circulation pump 80 is stopped.

[0026] In the hot water supply device 1A, the controller 10 can enhance the control responsiveness of the hot water outlet temperature by performing temperature control in combination with the control of the bypass ratio by the flow rate adjustment valve 90. On the other hand, if an error occurs in the opening degree of the flow rate adjustment valve 90 and an error from the set value occurs in the bypass ratio, there is a concern that the controllability of the hot water outlet temperature may decrease.

[0027] FIG. 2 shows a drive configuration of the flow rate adjustment valve 90 for controlling the bypass ratio. Referring to FIG. 2, the opening degree of the flow rate adjustment valve 90 changes in conjunction with the rotational position (angle) MPc of the stepping motor 150.

[0028] Since the bypass ratio, which is the flow rate ratio of the bypass path 22, is determined by the opening degree of the flow rate adjustment valve 90, the controller 10 stores a table 15 that defines the correspondence between the rotational position of the stepping motor 150 and the opening degree of the flow rate adjustment valve 90, and the correspondence between the opening degree of the flow rate adjustment valve 90 and the bypass ratio.

[0029] When the controller 10 calculates a bypass ratio for controlling the hot water temperature Th to the hot water supply set temperature Tr, in order to control the opening degree of the flow rate adjustment valve 90 so that the calculated bypass ratio is realized, the controller 10 controls the rotational position MPc of the stepping motor 150.

[0030] The controller 10 outputs a plurality of phase pulse signals PS1 to PSn to the stepping motor 150. For example, by the pulse signals PS1 to PSn, a positive pulse for increasing the number of pulses and a negative pulse for decreasing the number of pulses can be input to the stepping motor 150. The pulse signals PS1 to PSn correspond to an embodiment of the "control signal" of the stepping motor 150.

[0031] FIG. 3 is a conceptual graph for explaining the control of the rotational position of the stepping motor 150.

[0032] As shown in FIG. 3, the rotational position MPc of the stepping motor 150 changes in proportion to the number of pulses Nm increased or decreased by the input of a positive pulse or a negative pulse. For example, when changing the bypass ratio in the direction of changing the rotational position MPc upward in the vertical axis, the controller 10 generates the pulse signals PS1 to PSn so that a positive pulse is input to the stepping motor 150.

[0033] In addition, in FIG. 3, the relationship between the number of pulses Nm and the rotational position MPc is continuously represented by a straight line, but actually, the rotational position MPc shows a discrete characteristic in which it changes by a predetermined step amount every time the number of pulses Nm changes by 1.

[0034] Since the controller 10 can recognize the number of pulses Nm in FIG. 3 from the integrated value of the number of positive pulses and the number of negative pulses with respect to the stepping motor 150, the controller 10 can grasp the soft position MPs corresponding to the "control value" of the rotational position MPc from the number of pulses Nm and the step amount.

[0035] The controller 10 can calculate a command value for the bypass flow rate ratio to set the hot water outlet temperature Th to the hot water supply set temperature Tr, using the can body temperature Tb, the incoming water temperature Tw, and the hot water supply set temperature Tr. The command value may be calculated by combining feedback control based on the deviation between the hot water outlet temperature Th and the hot water supply set temperature Tr.

[0036] When the controller 10 obtains a target value for the rotational position of the stepping motor 150 corresponding to the opening degree of the flow rate adjustment valve 90 for realizing the calculated bypass ratio, the controller 10 generates pulse signals PS1 to PSn for the stepping motor 150 so that the soft position MPs (control value) matches the target value.

[0037] On the other hand, since the rotational position MPc of the stepping motor 150 is not feedback-controlled, a deviation (detuning) may occur between the soft position MPs recognized by integrating the number of pulses and the actual rotational position MPc. Therefore, the position reset of the stepping motor 150, which is an embodiment of the "rotational position initialization process", is periodically executed.

[0038] Referring to FIG. 2 again, the stepping motor 150 is provided with a reference position detection mechanism 155, which is hardware that generates a detection signal LS when the rotational position (angle) reaches a predetermined reference position. The reference position detection mechanism 155 can typically be constituted by a limit switch. The reference position can be determined, for example, to correspond to the rotational position of the stepping motor 150 at an opening degree equivalent to fully closed or fully open of the flow rate adjustment valve 90.

[0039] FIG. 4 shows a conceptual graph for explaining the position reset of the stepping motor.

[0040] The horizontal axis in FIG. 4 is the above-mentioned soft position MPs grasped by the controller 10, and the vertical axis is the actual rotational position (hereinafter also referred to as "hard position") MPc of the stepping motor 150.

[0041] When performing position reset, the controller 10 generates pulse signals PS1 to PSn so that the soft position MPs is changed toward the reference value MPr corresponding to the reference position in order to drive the rotational position of the stepping motor toward the reference position. When the actual rotational position of the stepping motor 150 reaches the reference position, the detection signal LS shown in FIG. 2 is input to the controller 10.

[0042] When the controller 10 receives the detection signal LS, it initializes (resets) the soft position MPs at that time to the reference value MPr. Thereafter, starting from the initialized soft position MPs (=MPr), the soft position MPs is updated step by step according to the integration of positive or negative pulses.

[0043] As shown in the characteristic line 101, when there is no error ΔMP between the soft position MPs and the hard position MPc, when the controller 10 performs position reset, it receives the detection signal LS when MPs = MPr. In this case, since the error ΔMP = 0, the soft position MPs is maintained at the current value.

[0044] On the contrary, when an error ΔMP shown by the characteristic line 102 occurs between the soft position MPs before initialization and the hard position MPc, the controller 10 receives the detection signal LS when MP = M1 before the soft position MPs reaches the reference value MPr. In this case, the error ΔMP = M1 - MPr (ΔMP < 0).

[0045] Conversely, when an error ΔMP shown by the characteristic line 103 occurs between the soft position MPs before initialization and the hard position MPc, the controller 10 receives the detection signal LS when MPs = M2 after the soft position MPs reaches the reference value MPr. In this case, the error ΔMP = M2 - MPr (ΔMP > 0).

[0046] When the error ΔMP is not 0 as in the characteristic lines 102 and 103, the soft position MPs is initialized from M1 or M2 to the reference value MPr.

[0047] FIG. 5 is a flowchart for explaining the control process of position reset. The control process shown in FIG. 5 is repeatedly activated by the controller 10.

[0048] Referring to FIG. 5, the controller 10 determines, in step (hereinafter also simply referred to as "S") 110, whether the position reset condition is satisfied. The determination in S110 is executed by comparing a predetermined operation parameter of the water heater 1A with a determination value.

[0049] For example, the operation parameter value in S110 can be the number of operations of the combustion mechanism 30. In this case, in S110, when the count value Nbr of the number of combustion times, which is incremented by 1 each time the combustion mechanism 30 changes from off to on, reaches the determination value Nr (Nbr≧Nr), it is determined as YES, and while Nbr<Nr, it is determined as NO.

[0050] When the position reset condition is satisfied (at YES determination in S110), the controller 10 executes the position reset described in FIG. 4 in S120. In S130, in response to the reception of the detection signal LS, the soft position MPs is initialized to the reference value MPr, and using the value of the soft position MPs before initialization, the error ΔMP shown in FIG. 4 is calculated. Also, when the position reset is executed, the count value Nbr, which is the operation parameter of the position reset condition, is cleared to zero.

[0051] Furthermore, the controller 10 sets, in S140, the position reset condition used for the determination (S110) of the position reset in subsequent times according to the magnitude of the error (|ΔMp|) calculated in S130. As described above, when the position reset condition is determined by the determination value Nr of the count value Nbr of the number of combustion times, the determination value Nr is set according to the magnitude of the error (|ΔMp|) calculated in S130.

[0052] FIG. 6 is a flowchart for explaining the setting process of the determination value of the position reset condition in S140.

[0053] Referring to FIG. 6, the controller 10 compares the magnitude of the error (|ΔMp|) with the reference range defined by the determination values N1 and N2 according to S210 and S220. As a result, as shown in FIG. 7, it is determined which of the region R1 where |ΔMp| is greater than the reference range (|ΔMp|>N1), the region R2 within the reference range (N2≦|ΔMp|≦N1), and the region R3 where |ΔMp| is smaller than the reference range (|ΔMp|<N2) |ΔMp| belongs to.

[0054] When |ΔMp| belongs to the region R1, that is, when the absolute value of the error is greater than the reference range (N1~N2), the controller 10 decreases the determination value Nr for the position reset condition by a predetermined value Nx from the current value according to S230. By decreasing the determination value Nr from the current value, the frequency of position reset can be increased compared to the current situation. That is, the determination value Nr will be changed so as to increase the frequency of position reset.

[0055] However, the decrease in the determination value Nr is executed with a predetermined lower limit value Nmin as the limit. Specifically, after decreasing the determination value Nr by S230, the controller 10 compares the decreased determination value Nr with the lower limit value Nmin by S240, and when Nr<Nmin (when the NO determination of S240), sets Nr = Nmin. On the other hand, when Nr≧Nmin (when the YES determination of S240), S250 is skipped and the determination value Nr in S230 is maintained. By providing the lower limit value Nmin for the determination value Nr, a limit can be set for increasing the execution frequency of position reset. That is, although the execution frequency of position reset cannot be directly specified, equivalently, an upper limit for the execution frequency of position reset can be set.

[0056] When |ΔMp| belongs to region R3, that is, when the absolute value of the error is smaller than the reference range (N1~N2), the controller 10 increases the determination value Nr of the position reset condition by a predetermined value Ny from the current value according to S270. By increasing the determination value Nr from the current value, the frequency of position reset can be reduced compared to the current situation. That is, the determination value Nr will be changed so as to reduce the frequency of position reset.

[0057] However, the increase in the determination value Nr is also executed within the limit of a predetermined upper limit value Nmax. Specifically, after increasing the determination value Nr by the controller 10 according to S270, the controller 10 compares the increased determination value Nr with the upper limit value Nmax according to S280. When Nr > Nmax (when the NO determination of S280), it is set to Nr = Nmax. On the other hand, when Nr ≤ Nmax (when the YES determination of S280), S290 is skipped and the determination value Nr at S270 is maintained. By providing the upper limit value Nmax for the determination value Nr, a limit can be set for reducing the execution frequency of position reset. That is, although the execution frequency of position reset cannot be directly specified, equivalently, a lower limit of the execution frequency of position reset can be provided.

[0058] On the other hand, when |ΔMp| belongs to region R2, that is, when the absolute value of the error is within the reference range, the controller 10 maintains the determination value Nr at the current value according to S260.

[0059] As a result, as shown in FIG. 7, when the absolute value of the error (|ΔMp|) at the time of position reset is larger than a predetermined reference range (between the determination values N1 and N2), the determination value Nr (that is, the position reset condition) can be changed so that the execution frequency of position reset increases. Thereby, in a situation where an error of the soft position MPs (control value) is likely to occur, by executing position reset before the error becomes large, it is possible to suppress the opening error of the flow rate adjustment valve 90.

[0060] Furthermore, when the absolute value of the error at the time of position reset (|ΔMp|) is smaller than a predetermined reference range, the determination value Nr, that is, the position reset condition can be changed so that the execution frequency of the position reset decreases. Thereby, in a situation where it is difficult for a soft position error to occur, by preventing the position reset from being executed excessively, it is possible to suppress power consumption and suppress a decrease in equipment durability.

[0061] On the other hand, when the absolute value of the error at the time of position reset (|ΔMp|) is within a predetermined reference range, the determination value Nr is maintained and the current execution frequency of the position reset is maintained.

[0062] As described above, in the water supply device according to the present embodiment, in a water supply device in which a valve whose opening degree is controlled using a stepping motor as a drive source is arranged, the execution frequency of the position reset can be adjusted according to the magnitude of the error of the control value of the rotation position obtained at the time of position reset. Thereby, the position reset (rotation position initialization process) of the stepping motor for controlling the opening degree of the valve can be executed at an appropriate frequency.

[0063] Note that when priority is given to suppressing the opening degree error, FIGS. 6 and 7 may be modified so that the determination value Nr of the position reset condition is maintained in both regions R2 and R3.

[0064] In addition, the operation parameters for determining the position reset condition are not limited to the number of operations of the combustion mechanism described above, and various conditions can be set. For example, it is also possible to execute the determination of S110 by comparing the integrated value of the operation time of the combustion mechanism 30, or the elapsed time since the previous execution of the position reset, etc. with the determination value. Alternatively, more directly, the number of times the opening degree of the flow rate adjustment valve 90 is changed may be counted and compared with the determination value as the operation parameter. Also in these cases, in S140 (FIG. 5), according to FIG. 7, the determination value of the position reset condition used in S110 can be set so as to increase, decrease, or maintain the execution frequency of the position reset according to the absolute value (|ΔMp|) of the error at the time of position reset.

[0065] Next, a modification of the configuration of the water heater according to the present embodiment will be further described. FIG. 8 shows a block diagram for explaining the configuration of the water heater 1B according to a modification of the present embodiment.

[0066] Referring to FIG. 8, the water heater 1B is a model that does not have an instant hot water circulation function, and the arrangement of the circulation port 13, the circulation path 23, and the circulation pump 80 is omitted from the water heater 1A of FIG. 1. The operation during the hot water supply operation of the water heater 1B is the same as that of the water heater 1A, and the flow rate adjustment valve 90 is also controlled in the same manner as the water heater 1A. Therefore, also in the water heater 1B, it is possible to similarly execute the position reset for the flow rate adjustment valve 90 whose opening degree is controlled using a stepping motor.

[0067] In addition, the present embodiment can be commonly applied to the position reset of the stepping motor without depending on the internal configuration of the water heater as long as it includes a valve arranged in the fluid flow path and whose opening degree is controlled using a stepping motor.

[0068] The embodiments disclosed this time should be considered illustrative in all respects and not restrictive. The scope of the present invention is shown not by the above description but by the claims, and it is intended that all modifications within the meaning and scope equivalent to the claims be included.

Explanation of Signs

[0069] 1A, 1B Water heater, 10 Controller, 11 Water inlet port, 12 Hot water outlet port, 13 Circulation port, 15 Table, 20 Water inlet path, 21 Check valve, 22 Bypass path, 23 Circulation path, 25 Hot water outlet path, 26, 27, 125 Connection points, 30 Combustion mechanism, 40 Heat exchanger, 71 - 73 Temperature detectors, 75 Flow rate detector, 80 Circulation pump, 90 Flow rate control valve, 100 Housing, 101 - 103 Characteristic lines, 110 Water inlet pipe, 120 Hot water outlet pipe, 130 Circulation pipe, 150 Stepping motor, 155 Reference position detection mechanism, 200 Hot water faucet, LS Detection signal, MPc Rotation position (hard position), MPr Reference value (reference position), MPs Soft position (control value), Nbr Count value, Nm Pulse number, Nmax Upper limit value (judgment value), Nmin Lower limit value (judgment value), Nr Judgment value (position reset condition), Nx, Ny Predetermined values, PS1 - PSn Pulse signals, Qf Flow rate detection value, Tb Tank body temperature, Th Hot water outlet temperature, Tw Water inlet temperature.

Claims

1. A hot water supply device, comprising a control valve disposed in a fluid flow path and having an opening degree controlled with a stepping motor as a drive source, and a controller configured to control a rotational position of the stepping motor to control the opening degree of the control valve, wherein the stepping motor is configured to output a detection signal to the controller when the rotational position reaches a predetermined reference position, and the controller based on a comparison between an operation parameter of the hot water supply device and a determination value, continuously generates a control signal for driving the rotational position of the stepping motor to the reference position until the detection signal is received from the stepping motor, thereby executing a rotational position initialization process, and when the rotational position initialization process is executed, when the detection signal is received, initializes a control value of the rotational position to a value corresponding to the reference position, and when an absolute value of an error between the control value before initialization and the reference position is larger than a predetermined reference range, changes the determination value so that a execution frequency of the rotational position initialization process increases. A hot water supply device.

2. The hot water supply device according to claim 1, wherein when the controller changes the determination value so as to increase the execution frequency, the controller restricts the execution frequency from exceeding a predetermined upper limit and changes the determination value.

3. The hot water supply device according to claim 1, wherein when the absolute value of the error when the detection signal is received during the execution of the rotational position initialization process by the controller is smaller than the reference range, the controller changes the determination value so that the execution frequency of the rotational position initialization process decreases.

4. The hot water supply device according to claim 3, wherein when the controller changes the determination value so as to decrease the execution frequency, the controller restricts the execution frequency from falling below a predetermined lower limit and changes the determination value.

5. The hot water supply device The heating device further includes a heating mechanism that heats at least a part of the fluid flowing through the flow path in which the control valve is disposed. The operation parameter includes one of the number of operations or the operation time of the heating mechanism, the number of times of changing the opening degree of the control valve, and the elapsed time from the previous execution timing of the rotation position initialization process. The water heater according to any one of claims 1 to 4.

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