Hot water temperature control device

Abstract

To enhance temperature control accuracy in a bypass mixing type hot water temperature control device.SOLUTION: A hybrid valve 80 distributes low-temperature water introduced to a water inflow passage 50 to can body piping 55 to a heat exchanger 10 and bypass piping 60. The hybrid valve 80 is configured to have a first region in which a flow ratio between a flow rate Q1 and a flow rate Q2 is changed without affecting a total flow rate Qt and a second region in which the flow ratio is fixed and the total flow rate Qt is changed, relative to an opening control value. A controller 200 controls a distribution valve by using a corrected flow rate ratio reflecting a correction amount based on an error between a first flow ratio backwardly calculated from a current opening control value of the hybrid valve 80 and a second flow ratio calculated from detection temperatures Tw, Tb, Th obtained by temperature sensors 110, 120, 130.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot water temperature adjustment device, and more particularly to a hot water temperature adjustment device of a bypass mixing type that mixes high temperature water and low temperature water. [Background technology]

[0002] 2. Description of the Related Art A bypass mixing type hot water temperature adjustment device, which adjusts the outlet hot water temperature by controlling the flow ratio between high-temperature water that has passed through a heat exchanger and low-temperature water that has bypassed the heat exchanger, is used in water heaters and the like.

[0003] Japanese Patent No. 3067498 (Patent Document 1) describes a configuration in which the valve opening of a bypass valve (distribution valve) for controlling the flow ratio of high-temperature water and low-temperature water is controlled by the number of steps of a stepping motor. Patent Document 1 also describes that the number of steps of the stepping motor is set by correcting the target number of steps calculated back from the target flow ratio using a correction number of steps according to a previously obtained reference characteristic relationship between the number of steps (valve opening) in the bypass valve and the flow ratio. The correction number of steps is calculated based on the deviation between the actual flow ratio calculated from the detected temperature and the target flow ratio.

[0004] Furthermore, Japanese Patent No. 4823149 (Patent Document 2) describes an embodiment of a mixing valve that mixes hot water and cold water to output hot water, which also has a function of throttling down only the amount of hot water when the water inlet is fully closed. Specifically, the mixing valve in Patent Document 2 has the characteristic of having a first region in which the opening areas of the water inlet and the hot water inlet gradually decrease and increase in conjunction with each other depending on the valve opening degree of the mixing valve, and a second region in which the opening area of ​​the hot water inlet changes from a maximum value to a minimum value when the water inlet is fully closed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 3067498 [Patent Document 2] Patent No. 4823149 Summary of the Invention [Problem to be solved by the invention]

[0006] It is understood that the mixing valve described in Patent Document 2 has a first region in which the flow rate ratio (mixing ratio) changes depending on the valve opening without affecting the output flow rate from the mixing valve (i.e., the total flow rate of cold water and hot water), and a second region in which the output flow rate from the mixing valve changes depending on the valve opening while the mixing ratio of cold water and hot water is fixed (total amount is hot water).

[0007] Here, assuming that the mixing valve of Patent Document 2 is applied to the bypass valve of the hot water supply apparatus of Patent Document 1, in the first region, by controlling the valve opening of the bypass valve using the number of correction steps, it is expected that the accuracy of temperature control can be improved by compensating for characteristic errors of the bypass valve and accurately setting the flow rate ratio of high temperature water and low temperature water.

[0008] However, in the mixing valve of Patent Document 2, in the second region, the mixing ratio does not change with respect to the valve opening, i.e., the number of steps of the bypass valve, so there is a concern that it may be difficult to compensate for characteristic errors of the bypass valve in that region.

[0009] In particular, in the case of the mixing valve of Patent Document 2, if a modified example is considered in which the minimum opening value of the water inlet is set greater than fully closed, thereby fixing the flow rate ratio (mixing ratio) of cold water and hot water to a constant value other than 0 in the second region, there is a risk that the temperature control accuracy will decrease due to insufficient compensation for characteristic errors of the bypass valve in the second region.

[0010] The present invention has been made to solve these problems, and an object of the present invention is to improve the temperature control accuracy in a bypass mixing type hot water temperature control device that uses a control valve having a region in which the flow rate ratio does not change in response to changes in the control value. [Means for solving the problem]

[0011] In one aspect of the present invention, a hot water temperature adjustment device is provided. The hot water temperature adjustment device mixes low temperature water and high temperature water and includes a first flow path, a second flow path, a first temperature detector, a second temperature detector, a third temperature detector, a control valve, and a control device. The first flow path passes low temperature water through a heating section that outputs high temperature water. The second flow path passes low temperature water without passing through the heating section. The first temperature detector detects the temperature of the low temperature water. The second temperature detector detects the temperature of the high temperature water. The third temperature detector detects the outlet hot water temperature after mixing the low temperature water and the high temperature water. The control valve is connected to the first flow path and the second flow path and controls the flow rates of the first flow path and the second flow path. The control device receives the first detected temperature, the second detected temperature, and the third detected temperature by the first temperature detector, the second temperature detector, and the third temperature detector, respectively, and a set temperature for the outlet hot water temperature, and sets a control value for the control valve for controlling the outlet hot water temperature to the set temperature. The control valve is configured to have a first region where the flow rate ratio of the first and second flow paths changes without affecting the total flow rate of the first and second flow paths in response to a change in the control value, and a second region where the flow rate ratio is fixed while the total flow rate decreases. The control device executes a process of updating a correction amount of the flow rate ratio in a time series manner based on a deviation between a first flow rate ratio calculated from a current control value of the control valve and a second flow rate ratio calculated from the first, second, and third detected temperatures in light of a reference characteristic relationship between the control value and the flow rate ratio of the control valve that is predetermined through the first and second regions, throughout the time when the control value is within the first region and throughout the time when the control value is within the second region, and sets the control value of the control valve using the corrected flow rate ratio reflecting the correction amount. Effect of the Invention

[0012] According to the present invention, in a hot water temperature control device of a bypass mixing type that employs a control valve having a region in which the flow rate ratio does not change with changes in the control value, the accuracy of temperature control can be improved by controlling the control valve using a correction amount based on the error between the flow rate ratio calculated back from the current control value of the control valve and the flow rate ratio calculated from the actual temperature. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic configuration diagram of a hot water supply device shown as a representative example of a hot water temperature adjustment device according to an embodiment of the present invention. [Diagram 2] 2 is a conceptual diagram illustrating input and output of a hybrid valve applied to the hot water supply device of FIG. 1. [Diagram 3] FIG. 2 is a conceptual diagram showing the characteristics of a hybrid valve applied to the hot water supply device of FIG. [Figure 4] FIG. 11 is a conceptual diagram illustrating a comparative example of offset learning of a hybrid valve. [Diagram 5] FIG. 4 is a conceptual diagram illustrating offset learning of a hybrid valve according to an embodiment of the present invention. [Figure 6] 4 is a flowchart illustrating a control process for a hybrid valve in the hot water supply device of FIG. [Figure 7] 4 is a flowchart illustrating combustion control in a combustion burner in the water heater of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 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 given the same reference characters, and their description will not be repeated in principle.

[0015] FIG. 1 is a schematic configuration diagram of a hot water supply device 100 shown as a representative example of a hot water temperature adjustment device according to an embodiment of the present invention.

[0016] Referring to FIG. 1, the water heating apparatus 100 includes a combustion can body (hereinafter also simply referred to as "can body") 5 which houses a heat exchanger 10 and a combustion burner 30 etc., a blower fan 40, a water inlet passage 50, can body piping 55, a bypass piping 60, a water outlet passage 70, a hybrid valve 80, and a controller 200.

[0017] The inlet passage 50 is connected to the boiler body piping 55 and the bypass piping 60 via a hybrid valve 80. Low-temperature water such as tap water is supplied to the inlet passage 50. The low-temperature water in the inlet passage 50 is distributed to the boiler body piping 55 and the bypass piping 60 via the hybrid valve 80. In this embodiment, a "control valve" for controlling the flow rate ratio of high-temperature water and low-temperature water in the bypass mixing method is configured using a hybrid valve 80 having characteristics described later.

[0018] The boiler body piping 55 passes low-temperature water through the heat exchanger 10. The low-temperature water introduced from the water inlet 50 into the boiler body piping 55 is heated by the heat generated by the combustion burner 30 as it passes through the heat exchanger 10. As a result, high-temperature water is output from the heat exchanger 10.

[0019] A main gas solenoid valve 32, a gas proportional valve 33, and capacity changeover valves 35a to 35c are arranged in a gas supply pipe 31 to the combustion burner 30. The main gas solenoid valve 32 has a function of turning on and off the supply of fuel gas to the combustion burner 30. The gas flow rate in the gas supply pipe 31 is controlled according to the opening degree of the gas proportional valve 33.

[0020] The capacity switching valves 35a to 35c are controlled to open and close in order to switch the number of burners to which fuel gas is supplied among the multiple combustion burners 30. The amount of heat generated in the boiler body 5 is proportional to the amount of gas supplied from all of the combustion burners 30, which is determined by a combination of the number of burners and the gas flow rate. Therefore, a setting map can be created in advance that determines a combination of the opening / closing pattern of the capacity switching valves 35a to 35c (number of burners) and the opening degree of the gas proportional valve 33 (gas flow rate) in accordance with the amount of heat required for the combustion burners 30.

[0021] In the can body 5, the fuel gas output from the combustion burner 30 is mixed with the combustion air from the blower fan 40. The amount of air blown by the blower fan 40 is controlled so that the air-fuel ratio with respect to the amount of gas supplied from the entire combustion burner 30 becomes a predetermined value (for example, an ideal air-fuel ratio). Since the amount of air blown by the blower fan 40 is proportional to the fan rotation speed, the rotation speed of the blower fan 40 is controlled according to a target rotation speed that is set according to changes in the amount of gas supplied. The blower fan 40 is provided with a rotation speed sensor 45 for detecting the fan rotation speed.

[0022] The mixture of fuel gas and combustion air is ignited by an ignition device (not shown), and the fuel gas is burned to generate a flame. Combustion heat generated by the flame from the combustion burner 30 is provided to the heat exchanger 10 in the boiler body 5.

[0023] The high-temperature water heated by the heat exchanger 10 is output toward the hot water outlet 70. An exhaust path 15 for exhausting the combustion exhaust gas after heat exchange is provided downstream of the boiler body 5 in the flow direction of the combustion gas. The heat exchanger 10 may be configured to include both a primary heat exchanger and a secondary heat exchanger.

[0024] The bypass piping 60 and the boiler body piping 55 are connected at a junction 75. Hot water at an appropriate temperature, adjusted by mixing high-temperature water from the boiler body piping 55 and low-temperature water from the bypass piping 60, is supplied to the hot water outlet path 70 downstream of the junction 75. The hot water in the hot water outlet path 70 is supplied to a predetermined hot water supply point, such as a hot water tap (not shown) in the kitchen or bathroom, or a hot water supply circuit to a bathtub (not shown).

[0025] In this way, hot water supply apparatus 100 is configured to include a hot water temperature adjustment device of a so-called bypass mixing type that mixes high temperature water that has passed through heat exchanger 10 and low temperature water that has bypassed heat exchanger 10 via hybrid valve 80. As will be described later, the flow rate ratio (mixing ratio) of high temperature water and low temperature water is controlled by an opening control value (described later) of hybrid valve 80 from controller 200.

[0026] 1, the boiler body piping 55 forms a "first flow path," and the bypass piping 60 forms a "second flow path." Furthermore, the heat exchanger 10 that receives heat from the combustion burner 30 forms an embodiment of a "heating section."

[0027] In the following, the flow rate of boiler body piping 55 (first flow path) is denoted as Q1, and the flow rate of bypass piping 60 (second flow path) is denoted as Q2. The flow rate of hot water discharged from outlet piping 70 corresponds to the total flow rate Qt (Qt=Q1+Q2) of hot water supply device 100, which is the sum of flow rates Q1 and Q2. Each flow rate is a flow rate per unit time, and the unit is, for example, liters / minute.

[0028] The temperature sensor 110 is provided on the boiler body piping 55 upstream of the heat exchanger 10 in order to detect the temperature of the low-temperature water. The temperature sensor 110 may be provided in the water inlet passage 50 or the bypass piping 60.

[0029] Temperature sensor 120 is disposed downstream of heat exchanger 10 in boiler body piping 55 in order to detect the temperature of the high-temperature water. That is, temperature sensor 120 is disposed upstream of junction 75. Temperature sensor 130 is disposed in hot water outlet passage 70 downstream of junction 75 in order to detect the temperature of the hot water at the outlet after the high-temperature water and the low-temperature water are mixed.

[0030] In the following, the temperature detected by temperature sensor 110 is referred to as inlet water temperature Tw, the temperature detected by temperature sensor 120 is referred to as boiler body temperature Tb, and the temperature detected by temperature sensor 130 is referred to as outlet hot water temperature Th. Temperature sensor 110 corresponds to the "first temperature detector," temperature sensor 120 corresponds to the "second temperature detector," and temperature sensor 130 corresponds to the "third temperature detector." Furthermore, inlet water temperature Tw, boiler body temperature Tb, and outlet hot water temperature Th correspond to the "first detected temperature," "second detected temperature," and "third detected temperature," respectively.

[0031] A flow rate sensor 150 is further disposed in the can body pipe 55. The flow rate sensor 150 can be typically configured by an impeller type flow rate sensor. The flow rate sensor 150 detects the flow rate Q1 of the can body pipe 55.

[0032] Controller 200 can be configured, for example, by a microcomputer. Controller 200 receives detection values ​​from each sensor and user operations, and generates control commands to each device in order to control the overall operation of water heating apparatus 100. User operations include on / off commands for the operation switch of water heating apparatus 100, and designation of a set temperature Tr corresponding to a target value for the outlet hot water temperature.

[0033] When the operation switch of water heating apparatus 100 is turned on, controller 200 turns on the combustion operation in boiler body 5 in response to flow rate Q1 detected by flow sensor 150 exceeding the minimum operating flow rate (MOQ). When the combustion operation is turned on, main gas solenoid valve 32 is opened, and the supply of fuel gas to combustion burner 30 begins, and is ignited by an ignition device (not shown). In response, water heating apparatus 100 starts a hot water supply operation. During the hot water supply operation, controller 200 controls the outlet water temperature according to the set temperature Tr.

[0034] When the operation switch of the water heating device 100 is turned off, or when the flow rate Q1 falls below the minimum operating flow rate (MOQ) during hot water heating operation, the supply of fuel gas to the combustion burner 30 is stopped, thereby terminating the hot water heating operation.

[0035] Next, the characteristics of the hybrid valve 80 applied to the hot water temperature adjustment device (hot water supply device 100) according to the present embodiment will be described in detail.

[0036] 2, the hybrid valve 80 has a first port 81 connected to the boiler body piping 55, a second port 82 connected to the bypass piping 60, and a third port 83 connected to the inlet passage 50. The hybrid valve 80 is configured to control the flow rates Q1 and Q2 by controlling the aperture of one or more valve bodies (not shown) according to an aperture control value X from the controller 200, thereby changing the opening areas of at least a portion of the first port 81, the second port 82, and the third port 83. For example, the valve bodies are driven to open and close by a stepping motor (not shown). In this case, the aperture control value X is represented by the number of steps of the stepping motor.

[0037] As an example, the opening areas of the first port 81 and the second port 82 each change according to the opening of the first valve element (not shown), while the sum of the two is controlled to maintain a constant value. On the other hand, the opening area of ​​the third port 83 is controlled according to the opening of the second valve element (not shown).

[0038] While the flow rate Q1 of the boiler body piping 55 changes according to the opening area of ​​the first port 81 and the flow rate Q2 of the bypass piping 60 changes according to the opening area of ​​the second port 82, the sum of the opening areas of the first port 81 and the second port 82 is constant, so the flow rate ratio k (defined as k = Q2 / Q1) of the flow rate Q1 and the flow rate Q2 changes according to the opening degree of the first valve body described above.

[0039] Furthermore, since the sum of the opening areas of the first port 81 and the second port 82 is constant, the total flow rate Qt (Q1+Q2) changes according to the opening area of ​​the third port 83 which depends on the opening degree of the second valve element described above.

[0040] FIG. 3 shows a characteristic diagram of the hybrid valve 80 with respect to the opening control value X. 3, the hybrid valve 80 is configured to have a first region (X=X1 to Xt) in which the flow rate ratio k changes without affecting the total flow rate Qt with respect to the opening control value X that changes between a minimum value X1 and a maximum value X2, and a region (X=Xt to X2) in which the total flow rate Qt changes while the flow rate ratio k is kept constant. Hereinafter, the first region is also referred to as the "temperature control region 91," and the second region is also referred to as the "flow rate control region 92."

[0041] The total flow rate Qt is maintained at a maximum flow rate Qmax in the temperature control region 91 (X=X1 to Xt), while in the flow rate control region 92 (X=Xt to X2), it is controlled to decrease from the maximum flow rate Qmax to a minimum flow rate Qmin as the opening control value X increases.

[0042] In contrast, in the temperature control region 91 (X=X1 to Xt), the flow rate ratio k is controlled to gradually decrease from a maximum value kmax to a minimum value kmin in response to an increase in the opening control value X, while in the flow rate control region 92 (X=Xt to X2), the flow rate ratio k is maintained at the minimum value kmin at X=Xt.

[0043] For example, in the temperature control region 91, the opening area of ​​the first port 81 and the opening area of ​​the second port 82 are changed in conjunction with each other so that the opening area of ​​the first port 81 gradually increases while the opening area of ​​the second port 82 gradually decreases as the opening control value X increases from the minimum value X1 to the boundary value Xt, while the opening area of ​​the third port 83 is maintained at a maximum value independent of the opening control value X in the temperature control region 91. This realizes the characteristics of the flow rate ratio k and the total flow rate Qt relative to the opening control value X in the temperature control region 91 shown in Fig. 3. The maximum flow rate Qmax is determined by the pressure of the low-temperature water introduced into the water inlet 50 (for example, the water pressure of the waterworks) and the opening of a hot water tap (not shown) at the hot water supply destination.

[0044] Furthermore, in the flow rate control region 92, the hybrid valve 80 can be configured so that as the opening control value X increases from the boundary value Xt to the maximum value X2, the opening area of ​​the third port 83 gradually decreases, while the opening areas of the first port 81 and the second port 82 are maintained in the state when X=Xt. This realizes the characteristics of the flow rate ratio k and the total flow rate Qt versus the opening control value X in the flow rate control region 92 shown in Fig. 3. The hybrid valve 80 controls the flow rate Q1 (high temperature water) and the flow rate Q2 (low temperature water) according to the characteristics of the flow rate ratio (Q2 / Q1) and the total flow rate (Q1+Q2) shown in Fig. 3.

[0045] In the following, it is assumed that the flow ratio kmin>0, i.e., a flow rate occurs in the bypass piping 60 even in the flow control region 92 (Q2>0). However, it is also possible to make the flow ratio kmin=0 (i.e., Q2=0) in the flow control region 92 by fully closing the second port 82 at X=X2.

[0046] Furthermore, the minimum flow rate Qmin of the total flow rate Qt at the maximum value X2 of the opening control value X can be set to Qmin=0 by fully closing the third port 83. On the other hand, it is also possible to make Qmin>0 by not fully closing the third port 83 at X=X2. However, as described above, when the flow rate Q1 falls below the minimum operating flow rate (MOQ), the combustion in the combustion burner 30 is stopped.

[0047] Therefore, in temperature control region 91, water heating apparatus 100 can control outlet hot water temperature Th to set temperature Tr by adjusting flow rate ratio k with opening control value X of hybrid valve 80. It will be understood that when the "heating section" in water heating apparatus 100, i.e., the maximum heating amount when the amount of heat generated by combustion burner 30 is set to a maximum value (for example, maximum gas flow rate and combustion by all burners), is equal to or greater than the required heating amount according to the product of total flow rate Qt and amount of temperature rise ΔT=Tr-Tw, it is possible to control the outlet hot water temperature by adjusting flow rate ratio k in temperature control region 91.

[0048] On the other hand, when the required heating amount becomes greater than the maximum heating amount, the outlet hot water temperature Th cannot be raised to the set temperature Tr unless the total flow rate Qt is reduced from the maximum flow rate Qmax. For this reason, it becomes necessary to control the outlet hot water temperature by adjusting the total flow rate Qt in the flow control region 92. Also, when the flow rate Q1 of the boiler body piping 55 is the upper limit flow rate (boiler body maximum flow rate Q1max) in terms of the durability performance of the heat exchanger 10, the flow rate is controlled in the flow control region 92 so that Q1≦Q1max.

[0049] The relationship of the following formula (1) is established among the flow rate Q1 of the boiler body piping 55, the flow rate Q2 of the bypass piping 60, the boiler body temperature Tb, the inlet water temperature Tw, and the outlet hot water temperature Th. Q2·(Th-Tw)=Q1·(Tb-Th) …(1)

[0050] From equation (1), the flow rate ratio k (k=Q2 / Q1) can be expressed by equation (2) using the boiler body temperature Tb, the inlet water temperature Tw, and the outlet water temperature Th. k=Q2 / Q1=(Tb-Th) / (Th-Tw) …(2)

[0051] Therefore, during hot water supply operation, the actual flow rate ratio k can be calculated back from the actual temperature value by substituting the temperatures detected by the temperature sensors 110, 120, and 130 into equation (2). Hereinafter, the flow rate ratio calculated in this manner is referred to as the actual flow rate ratio ktm.

[0052] On the other hand, the flow rate ratio k* for controlling the outlet heated water temperature Th to the set temperature Tr can be calculated by the following equation (3) in which the outlet heated water temperature Th is replaced with the set temperature Tr in equation (2). k*=Q2 / Q1=(Tb-Tr) / (Tr-Tw) …(3)

[0053] Theoretically, by setting the flow rate ratio by hybrid valve 80 according to the flow rate ratio k* calculated by equation (3), it is possible to control outlet heated water temperature Th to set temperature Tr.

[0054] For example, by measuring the actual flow rate ratio ktm relative to the opening control value X of the hybrid valve 80 based on the results of a prior actual test, it is possible to determine the correspondence relationship between the opening control value X (number of steps) and the flow rate ratio k in the hybrid valve 80. This makes it possible to determine in advance, as a reference characteristic line, the reference correspondence relationship between the opening control value X and the flow rate ratio k for the hybrid valve 80.

[0055] The controller 200 can then perform outlet hot water temperature control by back-calculating the opening control value X from the flow rate ratio k* obtained by substituting the detected temperatures of the boiler body temperature Tb and the inlet water temperature Tw and the set temperature Tr into equation (3) in accordance with the reference characteristic line, and controlling the hybrid valve 80.

[0056] However, the actual opening characteristic (Xk) of the hybrid valve 80 may differ from the above-mentioned reference characteristic line due to individual differences caused by component variations, differences in the operating environment, etc. In such cases, it becomes difficult to accurately achieve the flow ratio k* calculated by equation (3) due to the deviation of the opening characteristic from the reference characteristic line. As a result, there is a concern that the accuracy of temperature control will decrease due to an error in the outlet hot water temperature Th from the set temperature Tr caused by the error between the actual flow ratio and the flow ratio k*.

[0057] For this reason, Patent Document 1 describes a method of setting the number of steps of a stepping motor by correcting a target number of steps, which is calculated according to a reference characteristic line from a target flow rate ratio corresponding to the above-mentioned flow rate ratio k*, using a correction number of steps. The correction number of steps is calculated based on the deviation between the number of steps corresponding to the above-mentioned actual flow rate ratio ktm and the actual number of steps.

[0058] FIG. 4 shows, as a comparative example, the offset learning of the hybrid valve 80 according to the number of correction steps described in Patent Document 1.

[0059] 4, as described above, the reference characteristic line 300 is determined in advance as a reference correspondence relationship between the opening control value X and the flow rate ratio k of the hybrid valve 80. In contrast, when an actual characteristic line 305 of the hybrid valve 80 in the temperature control region 91 deviates from the reference characteristic line 300, the opening control value X of the hybrid valve 80 is corrected by this deviation (offset amount), thereby improving the temperature control accuracy.

[0060] 4, in the comparative example (Patent Document 1), a correction amount Xc of the opening control value X is calculated based on an error ΔX between an actual opening control value (number of steps) and an opening control value (number of steps) calculated backward from an actual flow rate ratio ktm. The correction amount Xc is updated every time the error is calculated, and is calculated by a so-called learning process.

[0061] However, in the hybrid valve 80 applied in this embodiment, there is a region (flow control region 92 in FIG. 3) in which the flow rate ratio k does not change with respect to a change in the opening control value X, and therefore, in this region, it becomes impossible to update the correction amount Xc of the opening control value X. For this reason, the difference between the actual characteristic line 305 and the reference characteristic line 300 cannot be reflected in the correction amount Xc.

[0062] As a result, during the period in which the opening of the hybrid valve 80 is controlled within the flow control region 92, and during the period immediately after the opening of the hybrid valve 80 changes from the flow control region 92 to the temperature control region 91, the flow ratio k by the hybrid valve 80 cannot be set as intended due to the difference between the actual characteristic line 305 and the reference characteristic line 300, which raises concerns about a decrease in temperature control accuracy.

[0063] In contrast, FIG. 5 shows a conceptual diagram illustrating offset learning of a hybrid valve according to an embodiment of the present invention.

[0064] 5, in this embodiment, the difference between the actual characteristic line 305 and the reference characteristic line 300 is learned as an error Δk of the flow ratio k, and is reflected in the opening control value of the hybrid valve 80. As a result, unlike the method of directly learning the error of the opening control value (number of steps) as in Patent Document 1, the flow ratio correction amount kc equivalent to the error (offset value) of the flow ratio k set by the hybrid valve 80 can be updated in a time series even within the flow control region 92. As a result, by learning the difference between the actual characteristic line 305 and the reference characteristic line 300, the above-mentioned decrease in temperature control accuracy can be suppressed even within the flow control region 92.

[0065] Although not shown in the figure, in the flow control region 92, the correspondence relationship between the opening control value X of the hybrid valve 80 and the total flow rate Qt, i.e., the reference characteristic line of the total flow rate, is also created in advance based on the results of actual machine tests, etc.

[0066] Fig. 6 is a flowchart for explaining the control process of the hybrid valve in the hot water supply device of Fig. 1. The process of the flowchart shown in Fig. 6 can be periodically executed by controller 200 during hot water supply operation. Although not shown in Fig. 6, controller 200 can acquire the detection values ​​(Tw, Tb, Tw, Q1) of each sensor for each control cycle in which the process shown in Fig. 6 is executed.

[0067] 6, in step (hereinafter also simply referred to as "S") 100, controller 200 calculates total flow rate Qt from flow rate Q1 detected by flow rate sensor 150. At this time, using a corrected flow rate ratio k[i] updated for each control cycle, as described later, in the i-th control cycle (i: natural number), total flow rate Qt[i] is expressed as Q2=k·Q1, so that it is calculated according to the following formula (4) using the detected value Q1[i] of flow rate Q1 in that control cycle. Note that the control cycle for i=1 corresponds to the control cycle at the start of hot water supply operation, and the initial value corresponding to i=0 can be appropriately set using a predetermined fixed value including zero, or a value at the end of the previous hot water supply operation. Qt[i]=Q1+Q2=(1+k[i])·Q1[i] …(4)

[0068] The controller 200 calculates the required heat amount Prq in S200 according to the product of the total flow rate Qt calculated in S100 and the temperature rise amount ΔT=Tr−Tw. Furthermore, the controller 200 compares the required heat amount Prq calculated in S200 with a maximum heat amount Pmax that is predetermined in accordance with the maximum value of the heat amount generated by the combustion burner 30 in S300.

[0069] When the maximum heating amount Pmax is equal to or greater than the required heating amount Prq (YES in S300), the controller 200 advances the process to S400, and executes temperature control by setting the opening control value X of the hybrid valve 80 within the temperature control region 91 (FIG. 3) in the corresponding control cycle. On the other hand, when the required heating amount Prq is greater than the required heating amount Prq (NO in S300), the controller 200 advances the process to S500, and executes flow control by setting the opening control value X of the hybrid valve 80 within the flow control region 92 (FIG. 3) in the corresponding control cycle.

[0070] Alternatively, in S300, it is possible to further combine a comparison between the can body's flow rate Q1 and the can body's maximum flow rate Q1max, and determine that temperature control is to be performed with a YES judgment when "the maximum heating amount Pmax is greater than or equal to the required heating amount Prq" and "the flow rate Q1 is less than or equal to the can body's maximum flow rate Q1max", while determining that flow rate control is to be performed with a NO judgment when "the required heating amount Prq is greater than the required heating amount Prq" or "the flow rate Q1 is greater than the can body's maximum flow rate Q1max".

[0071] When performing temperature control (S400), the controller 200 calculates a target flow rate ratio kst, which is a target value of the flow rate ratio k for temperature control, using the detected values ​​of the inlet water temperature Tw and the boiler body temperature Tb in the control cycle and the set temperature Tr according to the flow rate ratio k* in the above-mentioned equation (3) in S405. That is, kst is set to k*=(Tb-Tr) / (Tr-Tw).

[0072] In S410, the controller 200 calculates the actual flow rate ratio ktm from the detected values ​​of the inlet water temperature Tw, the boiler body temperature Tb, and the outlet hot water temperature Th in the control cycle in accordance with equation (2).

[0073] The controller 200 calculates the current opening control value X of the hybrid valve 80, i.e., the opening control value X set in the previous (i-1)th control cycle, back into an opening flow ratio kps according to the reference characteristic line 300 shown in FIG. 5 (S420). Furthermore, an error (offset) Δk of the flow ratio with respect to the reference characteristic line 300 is calculated in S430. Specifically, the flow ratio error Δk[i] in the i-th control cycle is calculated by the following formula (5) using the actual flow ratio ktm and the opening flow ratio kps calculated in S410 and S420 in that control cycle. That is, the opening flow ratio kps corresponds to one embodiment of the "first flow ratio", and the actual flow ratio ktm corresponds to one embodiment of the "second flow ratio". Δk[i]=kps-ktm …(5)

[0074] In step S440, the controller 200 executes a learning process for the flow ratio k, which uses the flow ratio error Δk to time-series update the flow ratio correction amount kc. For example, the flow ratio error Δk[i] in the i-th control cycle is reflected by the following equation (6), so that the flow ratio correction amount kc[i+1] used in the next control cycle can be updated from the current flow ratio correction amount kc[i]. kc[i+1]=α·kc[i]+β·Δk[i] …(6) α=L / (L+1),β=1 / (L+1)

[0075] Equation (6) updates the flow rate ratio correction amount kc in time series by smoothing the flow rate ratio error Δk in each control cycle using an exponential moving average.

[0076] In equation (6), α+β=1.0, and L, which determines α and β, is a parameter value for adjusting the smoothing speed. The larger the value of L, the more gradual the update of the flow ratio correction amount kc reflecting the change in the flow ratio error Δk. Conversely, the smaller the value of L, the more abrupt the update of the flow ratio correction amount kc. The parameter value L may be a fixed value, but it can also be set to a smaller value as the flow rate increases so that it changes according to the total flow rate Qt. In this way, by calculating the flow ratio correction amount kc from the flow ratio error Δk with a smoothing process represented by an exponential moving average, it is possible to suppress sudden changes in the flow ratio correction amount kc and stabilize the control.

[0077] In step S450, the controller 200 adds the target flow ratio kst calculated in step S405 to the flow ratio correction amount kc[i] calculated in step S440 of the previous control cycle to calculate the flow ratio k[i] in the current control cycle. That is, in temperature control (S400), the target flow ratio kst corresponds to the "target flow ratio," and the flow ratio k[i] corresponds to the "corrected flow ratio."

[0078] Next, in S600, the controller 200 sets the opening control value X[i] of the hybrid valve 80 in the i-th control cycle from the flow rate ratio k[i] calculated in S450 in accordance with the reference characteristic line 300 (FIG. 5). As a result, in the temperature control region, the error (offset) of the flow rate ratio k set by the hybrid valve 80 is suppressed, thereby improving the temperature control accuracy.

[0079] On the other hand, when the flow control is executed (S500), the controller 200 sets a target total flow rate Qst in the flow control in S505. The target total flow rate Qst in S505 is set to a value equal to or less than the maximum flow rate Qmax calculated by dividing the above-mentioned maximum heating amount Pmax by the required temperature increase amount (Tr-Tw). In addition, the target total flow rate Qst is limited so that the flow rate Q1 is set in a range equal to or less than the above-mentioned maximum boiler body flow rate under the flow rate ratio kmin in the flow control region 92 (FIG. 3).

[0080] Even when flow control is being performed (S500), the controller 200 executes S510 to S550 similar to S410 to S450, and continuously executes a learning process of the error (offset) of the flow ratio k, updating the flow ratio correction amount kc in a time series manner using the flow ratio error Δk in each control cycle.

[0081] During flow control where the flow rate ratio k is constant, the controller 200 sets the opening control value X[i] of the hybrid valve 80 in the i-th control cycle in S610 without reflecting the flow rate ratio correction amount kc. Specifically, the opening control value X[i] in S610 can be set according to the target total flow rate Qst set in S505 and the reference characteristic line of the hybrid valve 80 in the above-mentioned flow rate control region.

[0082] In addition, in a flow rate control region where flow rate ratio k by hybrid valve 80 is constant, the outlet hot water temperature may be controlled by the amount of heat provided by combustion burner 30. Fig. 7 shows a flowchart illustrating combustion control by the combustion burner in water heating apparatus 100.

[0083] 7, in step S700, controller 200 branches the combustion control process according to whether hybrid valve (HV) 80 is performing temperature control or flow rate control. The determination in step S700 can be performed in the same manner as in step S300 in FIG.

[0084] When temperature control is performed (when YES is determined in S700), the controller 200 sets a target temperature Tb* for the can body temperature Tb, and performs combustion control to adjust the amount of heat provided by the combustion burner 30 so that the detection value of the can body temperature Tb by the temperature sensor 120 becomes the target temperature Tb* (S710).

[0085] As described above, the amount of heat generated by the combustion burner 30 can be adjusted by a combination of the opening and closing pattern of the capacity switching valves 35a to 35c (the number of burners) and the opening degree of the gas proportional valve 33 (gas flow rate).

[0086] On the other hand, when flow control is executed (NO in S700), the controller 200 executes combustion control in S720 to adjust the amount of heat (i.e., the amount of gas) by the combustion burner 30 according to a comparison between the detected value of the outlet hot water temperature Th (temperature sensor 130) and the set temperature Tr. This makes it possible to execute combustion control for setting the outlet hot water temperature Th to the set temperature Tr even when the flow rate ratio k by the hybrid valve 80 is constant.

[0087] In addition, when the flow rate Q1 becomes larger than the boiler body maximum flow rate Q1max, in the flow rate control region 92, the flow rate is controlled so that Q1≦Q1max under the flow rate ratio kmin (Figure 3), while the amount of heating by the combustion burner 30 is controlled within a range below the maximum heating amount Pmax and the tapping temperature Th becomes the set temperature Tr.

[0088] In the flow control region, the accuracy of calculation of the total flow rate Qt in S100 is improved using the corrected flow rate ratio k[i] updated over time by S550, and this improves the accuracy of the branching decision between temperature control and flow rate control by S300, as well as the setting of the flow rate target value in S610 during flow rate control, thereby improving the accuracy of temperature control.

[0089] As described above, according to this embodiment, in a bypass mixing configuration to which a hybrid valve 80 is applied, in which there is a region (flow rate control region 92 in FIG. 3) in which the flow rate ratio k does not change with respect to a change in the opening control value X, it is possible to continuously execute the learning process of the error (offset) of the flow rate ratio k through the temperature control region 91 and the flow rate control region 92. This makes it possible to suppress a decrease in the accuracy of temperature control due to the influence of the error in the flow rate ratio k by the hybrid valve 80, which is caused by the difference between the actual characteristic line 305 and the reference characteristic line 300.

[0090] In particular, compared to the comparative example in Figure 4, the temperature control accuracy can be improved during the period when the opening of the hybrid valve 80 is controlled within the flow control region 92, and during the period immediately after the opening of the hybrid valve 80 changes from the flow control region 92 to the temperature control region 91.

[0091] 1 describes a configuration example in which the flow sensor 150 is disposed in the boiler body piping 55 and detects the flow rate Q1, but the control processes of Fig. 6 and Fig. 7 according to this embodiment can be similarly applied to a configuration in which the flow sensor 150 is disposed in the bypass piping 60 and detects the flow rate Q2. Alternatively, in a configuration in which the flow sensor 150 is disposed in the inlet passage 50 and detects the total flow rate Qt (Q1+Q2), a similar control process can be applied by calculating the flow rates Q1 and Q2 using a flow rate ratio k that has been similarly learned.

[0092] In addition, while Figure 1 shows an example in which the heat source of the "heating section" is the heat of combustion of a fuel such as gas, we would like to clarify that the hot water temperature control device of this embodiment can be applied to a configuration in which high-temperature water is generated by a "heating section" using any heat source (e.g., a heat pump or exhaust heat).

[0093] In the present embodiment, the hybrid valve 80 is connected between the inlet passage 50 and the boiler body pipe 55 and the bypass pipe 60 to control the distribution ratio of the low-temperature water from the inlet passage 50 to the boiler body pipe 55 and the bypass pipe 60. However, the hybrid valve 80 may be disposed at the junction 75 and connected between the outlet passage 70 and the boiler body pipe 55 and the bypass pipe 60. In this case, at the junction 75 in FIG. 2, the third port 83 is connected to the outlet passage 70, and the flow direction at each port is reversed. Then, the mixture ratio of the high-temperature water in the boiler body pipe 55 and the low-temperature water in the bypass pipe 60 is controlled by controlling the flow rates Q1 and Q2 according to the flow rate ratio (Q2 / Q1) and the total flow rate (Q1+Q2) shown in FIG. 3.

[0094] The embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present invention is defined by the claims, not the above description, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0095] 5 boiler body, 10 heat exchanger, 15 exhaust path, 30 combustion burner, 31 gas supply pipe, 32 main gas solenoid valve, 33 gas proportional valve, 35a to 35c capacity switching valve, 40 blower fan, 45 rotation speed sensor, 50 water inlet passage, 55 boiler body piping, 60 bypass piping, 70 hot water outlet passage, 75 junction, 80 hybrid valve, 81 first port, 82 second port, 83 third port, 91 temperature control area, 92 flow rate control area, 100 hot water supply device, 110, 120, 130 temperature sensor, 150 flow rate sensor, 200 controller, 300 reference characteristic line, 305 characteristic line, Pmax maximum heating amount, Prq required heating amount, Q1 flow rate (boiler body piping), Q2 flow rate (bypass piping), Qmax maximum flow rate, Qst target flow rate, Qt Total flow rate, Tb boiler temperature, Tb* target temperature (boiler temperature), Th outlet water temperature, Tr set temperature, Tw inlet water temperature, X opening control value (hybrid valve), k flow rate ratio, kc flow rate ratio correction amount, kps opening flow rate ratio, kst target flow rate ratio, ktm actual flow rate ratio.

Claims

1. A hot water temperature control device that mixes low temperature water and high temperature water, a first flow path for passing the low-temperature water through a heating section that outputs the high-temperature water; a second flow path through which the low-temperature water flows without passing through the heating section; A first temperature detector for detecting the temperature of the low-temperature water; A second temperature detector for detecting the temperature of the high-temperature water; a third temperature detector for detecting a temperature of the hot water after the low temperature water and the high temperature water are mixed; a control valve connected to the first flow path and the second flow path for controlling a flow rate of the first flow path and the second flow path; a control device which receives the first detected temperature, the second detected temperature, and the third detected temperature by the first temperature detector, the second temperature detector, and the third temperature detector, respectively, and a set temperature for the outlet hot water temperature, and sets a control value for the control valve for controlling the outlet hot water temperature to the set temperature, the control valve is configured to have a first region in which a flow rate ratio of the first flow path and the second flow path changes without affecting a total flow rate of the first flow path and the second flow path in response to a change in the control value, and a second region in which the flow rate ratio is fixed while the total flow rate decreases, The control device includes: a first flow rate ratio calculated from the current control value of the control valve and a second flow rate ratio calculated from the first detected temperature, the second detected temperature, and the third detected temperature, in light of a reference characteristic relationship between the control value of the control valve and the flow rate ratio, the reference characteristic relationship being determined in advance through the first region and the second region, and the process of updating a correction amount for the flow rate ratio in a time series manner is performed throughout the time when the control value is within the first region and the time when the control value is within the second region, and the control value of the control valve is set using the corrected flow rate ratio reflecting the correction amount.

2. Further comprising a flow detector disposed in the first flow path or the second flow path, The hot water temperature control device of claim 1, wherein when the required heating amount according to the product of the total flow rate calculated using the detected flow rate by the flow detector and the corrected flow rate ratio and the temperature difference between the first detected temperature and the set temperature is equal to or less than the maximum heating amount when the output value of the heating section is at its maximum value, the control device sets the control value of the control valve within the first region, while when the required heating amount is greater than the maximum heating amount, the control device sets the control value of the control valve within the second region.

3. The hot water temperature control device of claim 2, wherein the control device calculates the control value of the control valve within the second region so that, when the required heating amount is equal to or greater than the maximum heating amount, the total flow rate is controlled to a target flow rate that is set to be equal to or less than a maximum flow rate obtained by dividing the maximum heating amount by the temperature difference.

4. The hot water temperature control device of claim 2, wherein when the required heating amount is smaller than the maximum heating amount, the control device sets the control value of the control valve from a corrected flow rate ratio in which a correction amount is reflected in a target flow rate ratio calculated to control the outlet hot water temperature to a set temperature in accordance with the reference characteristic relationship.

5. The hot water temperature control device of claim 4, wherein when the required heating amount is smaller than the maximum heating amount, the control device calculates the target flow rate ratio according to a ratio between the temperature difference between the set temperature and the first detected temperature and the temperature difference between the second detected temperature and the set temperature.

6. The hot water temperature adjustment device according to claim 1 , wherein the second flow rate ratio is calculated according to a ratio of a temperature difference between the third detected temperature and the first detected temperature to a temperature difference between the second detected temperature and the third detected temperature.

7. 7. The hot water temperature adjustment device according to claim 1, wherein the correction amount is calculated by smoothing a transition of the deviation in a time axis direction.

8. The hot water temperature adjustment device according to claim 7 , wherein the correction amount is calculated by performing exponential smoothing on the deviation.

Images