Patent Application
20250189172
This application claims the priority benefit of Japan Application No. 2023-207422, filed on Dec. 8, 2023. The entirety of the above-described patent application is hereby incorporated by reference herein and made a part of the present specification.
The disclosure relates to a hot water supply device, and more specifically, to a hot water supply device including a valve that is controlled for opening degree by being driven by a stepping motor.
Japanese Patent No. 4090413 (Patent Document 1) describes a configuration in a linked hot water supply system composed of multiple hot water supply devices connected in parallel, in which each hot water supply device includes a flow control valve having a stepping motor (pulse motor) as its drive source. Since the stepping motor changes rotational position (angle) through open-loop control in response to digital pulse input, it is advantageous in terms of cost including ease of control.
In Patent Document 1, a flow rate of outflow hot water from each hot water supply device is controlled by an opening degree of each flow control valve. Furthermore, Patent Document 1 describes executing position reset (rotational position initialization processing) for each flow control valve to eliminate positional deviation (step-out) of the stepping motor. By periodically executing the position reset, it is possible to suppress an error between an actual valve opening degree and a valve opening degree recognized by a control part due to deviation in the rotational position of the stepping motor.
As also described in Patent Document 1, in the position reset, a state in which a pulse signal is applied to the stepping motor to change the valve opening degree continues until receipt of a hard detection signal which is generated when the valve opening degree reaches a reference opening degree.
Accordingly, if the frequency of the position reset is excessively low, there is a concern about the aforementioned error in valve opening degree. On the other hand, if the frequency is excessively high, there is a concern about problems such as increased power consumption of the stepping motor and decreased durability of the equipment.
A hot water supply device is provided, including a control valve and a controller. The control valve is arranged in a flow path of a fluid, and has an opening degree controlled with a stepping motor as a drive source. The controller controls a rotational position of the stepping motor 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, based on a comparison between an operation parameter of the hot water supply device and a determination value, executes rotational position initialization processing by continuously generating a control signal to drive the rotational position of the stepping motor to the reference position until receiving the detection signal from the stepping motor. Furthermore, during execution of the rotational position initialization processing, upon receiving the detection signal, the controller 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 outside and larger than a predetermined reference range, changes the determination value so that an execution frequency of the rotational position initialization processing increases.
According to the disclosure, in a hot water supply device in which a valve is arranged which has an opening degree controlled with a stepping motor as a drive source, rotational position initialization processing of the stepping motor is executed at an appropriate frequency.
In one aspect of the disclosure, a hot water supply device is provided. The hot water supply device includes a control valve and a controller. The control valve is arranged in a flow path of a fluid, and has an opening degree controlled with a stepping motor as a drive source. The controller controls a rotational position of the stepping motor 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, based on a comparison between an operation parameter of the hot water supply device and a determination value, executes rotational position initialization processing by continuously generating a control signal to drive the rotational position of the stepping motor to the reference position until receiving the detection signal from the stepping motor. Furthermore, during execution of the rotational position initialization processing, upon receiving the detection signal, the controller 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 outside and larger than a predetermined reference range, changes the determination value so that an execution frequency of the rotational position initialization processing increases.
According to the disclosure, in the hot water supply device in which a valve is arranged which has an opening degree controlled with a stepping motor as a drive source, the rotational position initialization processing of the stepping motor can be executed at an appropriate frequency.
An embodiment of the disclosure will be described below in detail with reference to the drawings. In the following, the same or equivalent portions in the drawings are denoted by the same reference numerals, and description thereof will not be repeated in principle.
Referring to
The water entry path 20 is formed between the water entry port 11 and an input side (upstream side) of the heat exchanger 40 via the check valve 21. The combustion mechanism 30 is typically composed of a burner that generates heat by combustion of gas or petroleum or the like. The heat exchanger 40 heats and raises the temperature of low-temperature water (fluid) introduced through the water entry path 20 by using the heat generated by the combustion mechanism 30. The combustion mechanism 30 and the heat exchanger 40 constitute one embodiment of a “heating mechanism”.
The hot water output path 25 is formed between an output side (downstream side) of the heat exchanger 40 and the hot water output port 12. The bypass path 22 is connected between the water entry path 20 and the hot water output path 25 without via the heat exchanger 40. The bypass path 22 is arranged to be connected between a portion (in
A temperature detector 71 is arranged in the water entry path 20. The temperature detector 71 detects an inflow water temperature Tw before heating by the heat exchanger 40. In contrast, temperature detectors 72 and 73 are arranged in the hot water output path 25. The temperature detector 72 is arranged downstream of the connection point 26 with the bypass path 22 in the hot water output path 25 and detects an outflow hot water temperature Th. On the other hand, the temperature detector 73 is arranged upstream of the connection point 26 and detects a can body temperature Tb which corresponds to an output temperature from the heat exchanger 40. Each fluid temperature detected by the temperature detectors 71 to 73 are input to the controller 10.
Furthermore, the hot water supply device 1A is provided with a flow rate detector 75. For example, in the water entry path 20, the flow rate detector 75 is arranged downstream of the connection point 27 with the circulation path 23 and of the flow control valve 90 that is located at a branching point with the bypass path 22, so as to detect a flow rate (can body flow rate) of an object heated in the heat exchanger 40. A flow rate detected value Qf from the flow rate detector 75 is input to the controller 10.
When a hot water faucet 200 is opened and a hot water supply destination executes hot water supply use, low-temperature water is introduced into the water entry path 20 due to a supply pressure of the low-temperature water. Accordingly, when the flow rate detector 75 detects a flow rate exceeding a minimum operating flow rate (MOQ) while an operation switch of the hot water supply device 1A is on, the controller 10 turns on the combustion mechanism 30, thereby starting a hot water supply operation. The hot water faucet 200 is shown as a representative example of the “hot water supply destination” of the hot water supply device 1A. This hot water supply destination may include an electromagnetic valve that turns on and off the hot water output to a bathtub or the like, and is not limited to being directly opened and closed by user operation. When the hot water faucet 200 is closed and the hot water supply destination stops the hot water supply use, low-temperature water is prevented from being introduced into the water entry path 20. Accordingly, in response to the detected value from the flow rate detector 75 falling below the minimum operating flow rate (MOQ), the controller 10 turns off the combustion mechanism 30, thereby ending the hot water supply operation.
During the hot water supply operation, high-temperature water heated by the combustion mechanism 30 and the heat exchanger 40 is mixed with the low-temperature water passing through the bypass path 22, then passes through the hot water output port 12, and is output to the hot water faucet 200 from the hot water output piping 120. During a normal hot water supply operation, as the circulation pump 80 is stopped by the controller 10, the fluid temperature (outflow hot water temperature Th) detected by the temperature detector 72 is controlled by the controller 10 to reach a hot water supply set temperature Tr input to a remote controller (not shown). The controller 10, which corresponds to one embodiment of a “controller”, is typically composed of a microcomputer.
In the hot water supply device 1A, a portion of low-temperature water bypasses the heat exchanger 40 without being heated, and is mixed downstream of the heat exchanger 40 as it is, thereby enabling supply of hot water at an appropriate temperature from the hot water output port 12. Thus, the output temperature (can body temperature) from the heat exchanger 40 (heating mechanism) can be made higher than the hot water supply set temperature Tr. Accordingly, the drain generated by cooling the exhaust from the combustion mechanism 30 on a surface of the heat exchanger 40 can be suppressed.
The controller 10 can control the outflow hot water temperature through a combination of control of a heating amount (generated heat amount) by the combustion mechanism 30 and control of a bypass flow ratio by the flow control valve 90.
In the hot water supply device 1A, when the hot water supply operation is stopped, in which the hot water supply use is stopped due to the closure of the hot water faucet 200 or the like, the temperature of the fluid staying within the hot water output path 25 and the hot water output piping 120 falls. Thus, there is a concern that it may take time to supply hot water at an appropriate temperature to the hot water faucet 200 after the start of the next hot water supply operation. Hence, by arranging the circulation port 13, the circulation path 23, and the circulation pump 80 in the hot water supply device 1A, an immediate hot water supply operation function for quickly supplying high-temperature water after the start of hot water supply operation is provided.
The circulation path 23 is formed between the circulation port 13 and the water entry path 20 (connection point 27). The circulation pump 80 is interposed and connected to the circulation path 23. Alternatively, the circulation pump 80 may be interposed and connected to the circulation piping 130 outside the housing 100. The operation and stoppage of the circulation pump 80 are controlled by the controller 10.
For example, during a period during which an immediate hot water supply operation mode is turned on by switch operation or timer setting, an immediate hot water supply operation can be started in response to no hot water supply use being present and a fluid temperature (for example, can body temperature Tb and/or outflow hot water temperature Th detected by temperature detectors 72 and 73) falling below an immediate hot water supply start determination temperature (which is, for example, set to a predetermined temperature lower than the hot water supply set temperature).
The immediate hot water supply operation is realized by forming an immediate hot water circulation path that includes the heat exchanger 40 (heating mechanism) through operation of the circulation pump 80 during the stoppage of hot water supply use from the hot water faucet 200 or the like. The immediate hot water circulation path is composed of a loop that starts from the circulation port 13, passes through the circulation path 23, water entry path 20 (downstream of connection point 27), heat exchanger 40, hot water output path 25, hot water output port 12, and hot water output piping 120 (upstream of connection point 125), and circulation piping 130, and then returns to the circulation port 13.
When the immediate hot water circulation path is formed by operation of the circulation pump 80, the combustion mechanism 30 is operated as the flow detected value Qf from the flow rate detector 75 exceeds the MOQ. Accordingly, the hot water within the immediate hot water circulation path is heated. The immediate hot water supply operation is ended due to the fact that a fluid temperature (for example, inflow water temperature Tw or outflow hot water temperature Th detected by temperature detector 71 or 72) within the immediate hot water circulation path reaches an immediate hot water supply end determination temperature (for example, hot water supply set temperature), thus stopping the heating by the combustion mechanism 30 and stopping the circulation pump 80.
In the hot water supply device 1A, by performing temperature control combined with control of a bypass ratio by the flow control valve 90, the controller 10 is able to improve control responsiveness of the outflow hot water temperature. On the other hand, there is a concern that if an error occurs in the opening degree of the flow control valve 90, and an error occurs between the bypass ratio and a set value thereof, controllability for the outflow hot water temperature may decrease.
Referring to
The bypass ratio being a flow rate ratio of the bypass path 22 is determined by the opening degree of the flow control valve 90. Thus, the controller 10 stores a table 15 that defines a correspondence relationship between the rotational position of the stepping motor 150 and the opening degree of the flow control valve 90 as well as a correspondence relationship between the opening degree of the flow control valve 90 and the bypass ratio.
The controller 10, upon calculating a bypass ratio for controlling the outflow hot water temperature Th to the hot water supply set temperature Tr, controls the rotational position MPc of the stepping motor 150 in order to control the opening degree of the flow control valve 90, so that the calculated bypass ratio can be achieved.
The controller 10 outputs pulse signals PS1 to PSn of multiple phases to the stepping motor 150. For example, by the pulse signals PS1 to PSn, a positive pulse that increases the pulse number and a negative pulse that decreases the pulse number can be input to the stepping motor 150. The pulse signals PS1 to PSn correspond to one embodiment of a “control signal” of the stepping motor 150.
As shown in
In
Since the controller 10 is able to recognize the pulse number Nm shown in
The controller 10 is able to calculate a command value for the bypass flow ratio for making the outflow hot water temperature Th equal to the hot water supply set temperature Tr using the can body temperature Tb, the inflow water temperature Tw, and the hot water supply set temperature Tr. This command value may be calculated by combining feedback control based on a deviation in the outflow hot water temperature Th and the hot water supply set temperature Tr.
When the controller 10 obtains a target value of the rotational position of the stepping motor 150 corresponding to the opening degree of the flow control valve 90 for achieving the calculated bypass ratio, the controller 10 generates the pulse signals PS1 to PSn for the stepping motor 150 to make the soft position MPs (control value) match this target value.
On the other hand, since the rotational position MPc of the stepping motor 150 is not feedback-controlled, there is a possibility of a deviation (step-out) occurring between the soft position MPs recognized by integration of the pulse number and the actual rotational position MPc. Hence, position reset of the stepping motor 150, which is one embodiment of “rotational position initialization processing”, is periodically executed.
Referring again to
In
During execution of the position reset, in order to drive a rotational position of a stepping motor toward a reference position, the controller 10 generates the pulse signals PS1 to PSn so that the soft position MPs changes toward a reference value MPr corresponding to the reference position. When the actual rotational position of the stepping motor 150 reaches the reference position, the detection signal LS shown in
Upon receiving the detection signal LS, the controller 10 initializes (resets) the soft position MPs at that point to the reference value MPr. Subsequently, starting from the soft position MPs (=MPr) after initialization, the soft position MPs is updated in increments according to the integration of positive pulses or negative pulses.
As shown by a characteristic line 101, if there is no error ΔMP between the soft position MPs and the hard position MPc, upon executing the position reset, the controller 10 receives the detection signal LS at the time of MPs=MPr. In this case, since the error ΔMP=0, the soft position MPs is maintained at its current value.
In contrast, if an error ΔMP shown by a characteristic line 102 occurs between the soft position MPs before initialization and the hard position MPc, the controller 10 receives the detection signal LS at the time of MPs=M1 before the soft position MPs reaches the reference value MPr. In this case, the error ΔMP=M1−MPr (ΔMP<0).
Conversely, if an error ΔMP shown by a characteristic line 103 occurs between the soft position MPs before initialization and the hard position MPc, the controller 10 receives the detection signal LS at the time of MPs=M2 after the soft position MPs has reached the reference value MPr. In this case, the error ΔMP=M2−MPr (ΔMP>0).
As shown by the characteristic lines 102 and 103, when the error ΔMP is not 0, the soft position MPs is initialized from M1 or M2 to the reference value MPr.
Referring to
For example, an operation parameter value in S110 can be set as the number of operations of the combustion mechanism 30. In this case, if a count value Nbr of combustion occurrences, which is incremented by 1 each time the combustion mechanism 30 changes from off to on, reaches a determination value Nr, the determination result of S110 is YES (Nbr≥Nr); while Nbr<Nr, the determination result of S110 is NO.
If the position reset condition is established (when the determination result of S110 is YES), the controller 10 executes the position reset described in
Furthermore, in S140, the controller 10 sets the position reset condition to be used in the next and subsequent position reset determinations (S110) according to a magnitude (|ΔMP|) of the error calculated in S130. As mentioned above, if the position reset condition is determined by the determination value Nr of the count value Nbr of combustion occurrences, the determination value Nr is set according to the magnitude (|ΔMP|) of the error calculated in S130.
Referring to
When |ΔMP| belongs to region R1, that is, when the absolute value of the error is larger than the reference range (N1 to N2), in S230, the controller 10 decreases the determination value Nr of the position reset condition by a predetermined value Nx from a current value of the determination value Nr. By decreasing the determination value Nr from its current value, the frequency of the position reset can be increased from the current state. That is, the determination value Nr is changed to increase the frequency of the position reset.
However, decreasing the determination value Nr is executed with a predetermined lower limit value Nmin as a limit. Specifically, after the determination value Nr is decreased in S230, the controller 10 compares the determination value Nr after decrease with the lower limit value Nmin in S240, and sets Nr=Nmin when Nr<Nmin (when the determination result of S240 is NO). On the other hand, when Nr≥Nmin (when the determination result of S240 is YES), S250 is skipped, and the determination value Nr at S230 is maintained. By setting the lower limit value Nmin for the determination value Nr, a limit can be set on increase in an execution frequency of the position reset. That is, while the execution frequency of the position reset cannot be directly specified, an upper limit can be equivalently set on the execution frequency of the position reset.
When |ΔMP| belongs to region R3, that is, when the absolute value of the error is small than the reference range (N1 to N2), in S270, the controller 10 increases the determination value Nr of the position reset condition by a predetermined value Ny from the current value of the determination value Nr. By increasing the determination value Nr from its current value, the frequency of the position reset can be decreased from the current state. That is, the determination value Nr is changed to decrease the frequency of the position reset.
However, increasing the determination value Nr is also executed with a predetermined upper limit value Nmax as a limit. Specifically, after the determination value Nr is increased in S270, the controller 10 compares the determination value Nr after increase with the upper limit value Nmax in S280, and sets Nr=Nmax when Nr≥Nmax (when the determination result of S280 is NO). On the other hand, when Nr≤Nmax (when the determination result of S280 is YES), S290 is skipped, and the determination value Nr at S270 is maintained. By setting the upper limit value Nmax for the determination value Nr, a limit can be set on decrease in the execution frequency of the position reset. That is, while the execution frequency of the position reset cannot be directly specified, a lower limit can be equivalently set on the execution frequency of the position reset.
On the other hand, when |ΔMP| belongs to region R2, that is, when the absolute value of the error is within the reference range, in S260, the controller 10 maintains the determination value Nr at its current value.
As a result, as shown in
Furthermore, when the absolute value (|ΔMP|) of the error at the time of the position reset is smaller than the predetermined reference range, the determination value Nr, that is, the position reset condition, can be changed to decrease the execution frequency of the position reset. Accordingly, in a situation where an error in the soft position is less likely to occur, by avoiding excessive execution of the position reset, as power consumption is suppressed, reduction in equipment durability can be suppressed.
In contrast, when the absolute value (|ΔMP|) of the error at the time of the position reset is within the predetermined reference range, the determination value Nr is maintained, and the current execution frequency of the position reset is maintained.
In this way, in the hot water supply device according to the present embodiment, which includes a valve controlled for opening degree with the stepping motor as a drive source, the execution frequency of the position reset can be adjusted according to the magnitude of the error in the control value of the rotational position obtained at the time of the position reset. Accordingly, the position reset (rotational position initialization processing) of the stepping motor for valve opening degree control can be executed at an appropriate frequency.
If suppression of opening degree error is prioritized,
An operation parameter for determining the position reset condition is not limited to the aforementioned number of operations of the combustion mechanism, and various conditions can be set. For example, it is possible to execute the determination in S110 by comparing an integrated value of operation time of the combustion mechanism 30 or a time elapsed since the previous execution of the position reset with a determination value. Alternatively, more directly, the number of times the opening degree of the flow control valve 90 is changed can be counted and compared with the determination value as an operation parameter. In these cases as well, in S140 (
Next, a modification of the configuration of the hot water supply device according to the present embodiment will be further described.
Referring to
In the present embodiment, if a valve is provided which is arranged in a fluid flow path and controlled for opening degree using a stepping motor, the position reset of the stepping motor can be commonly applied regardless of the internal configuration of the hot water supply device.
The embodiments disclosed herein are examples in all aspects and should not be interpreted as limitations. The scope of the disclosure is defined by claims instead of the above description, and it is intended to include all modifications within the scope of the claims and the equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2023-207422 | Dec 2023 | JP | national |
