Hot water supply device

Abstract

The present invention addresses the problem of improving temperature control accuracy in a bypass mixing hot water supply device. Hot water is supplied by mixing the high-temperature water flowing through the tank pipe (55) with the low-temperature water flowing through the bypass pipe (60). The mixing valve (80) is configured so as to have a first section in which the flow rate ratio of the flow rate (Q1) of the high-temperature water to the flow rate (Q2) of the low-temperature water changes and a second section in which the flow rate ratio is fixed and the total flow rate (Qt) changes with respect to the opening degree control value. When the total flow rate is equal to or less than the limited flow rate, temperature control is performed in which the mixing valve operates in the first section. When the total flow rate is greater than the limited flow rate, flow rate control is performed in which the mixing valve operates in the second section. During temperature control, the amount of heat generated by the combustion burner (30) is adjusted in order to control the tank temperature (Tb) to a tank set temperature set so as to decrease as the total flow increases.

Description

Technical Field

[0001] The present invention relates to a hot water supply device, and more particularly to a hot water supply device of a bypass mixing type for mixing high-temperature water and low-temperature water. Background Art

[0002] A hot water supply device using a bypass mixing method adjusts the outlet heated water temperature by controlling the flow rate ratio of high-temperature water passing through a heat exchanger and low-temperature water bypassing the heat exchanger.

[0003] Japanese Patent Gazette No. 3067498 (Patent Document 1) describes a structure for controlling the valve opening of a bypass valve (distribution valve) for controlling the flow ratio of high-temperature water to low-temperature water by the number of steps of a stepping motor. Patent Document 1 describes the following: According to a pre-calculated reference characteristic relationship between the number of steps of the bypass valve (valve opening) and the flow ratio, the number of steps of the stepping motor is corrected by using a correction number of steps to correct the target number of steps calculated inversely from the target flow ratio, thereby setting the number of steps of the stepping motor. The correction number of steps is calculated based on the deviation between the actual flow ratio calculated based on the detected temperature and the target flow ratio.

[0004] In addition, Japanese Patent No. 4823149 (Patent Document 2) describes a mixing valve that has a function of reducing the amount of hot water when the water inlet is fully closed as one example of a mixing valve that mixes hot water with water to output warm water. Specifically, the mixing valve of Patent Document 2 has the following characteristics: according to the valve opening of the mixing valve, there is a first interval in which the opening areas of the water inlet and the hot water inlet are gradually reduced and gradually increased in conjunction with each other, and a second interval 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.

[0005] [Prior art literature]

[0006] [Patent Document]

[0007] [Patent Document 1] Japanese Patent No. 3067498

[0008] [Patent Document 2] Japanese Patent No. 4823149 Summary of the invention

[0009] [Problems to be solved by the invention]

[0010] In the mixing valve described in Patent Document 2, it can be understood that there is a first interval in which the flow ratio (mixing ratio) changes according to the valve opening without affecting the output flow from the mixing valve (i.e., the total flow of water and hot water), and a second interval in which the output flow from the mixing valve changes according to the valve opening when the mixing ratio of water and hot water is fixed (the entire amount is hot water).

[0011] Here, if it is assumed that the mixing valve of Patent Document 2 is applied to the structure of the bypass valve of the hot water supply device of Patent Document 1, in the temperature control when the mixing valve is operating in the first interval, the outlet hot water temperature can be controlled by adjusting the flow ratio, so the temperature of the high-temperature water does not directly affect the outlet hot water temperature. In contrast, in the temperature control when the mixing valve is operating in the second interval, since the flow ratio is fixed, the temperature of the high-temperature water directly affects the outlet hot water temperature. Therefore, when switching from the temperature control when the mixing valve is operating in the first interval to the temperature control when the mixing valve is operating in the second interval, there is a concern that the temperature control accuracy will decrease.

[0012] The present invention is made to solve such a problem, and an object of the present invention is to improve the temperature control accuracy in a bypass mixing type hot water supply device that uses a control valve having a region where the flow ratio does not change with respect to changes in a control value.

[0013] [Technical means to solve the problem]

[0014] In one aspect of the present invention, a hot water supply device is provided. The hot water supply device for mixing low-temperature water with high-temperature water includes: a heating unit, a first flow path, a second flow path, a flow detector, a control valve, and a control device. The heating unit heats the low-temperature water and outputs the high-temperature water. The first flow path is used to allow the low-temperature water to flow to the heating unit. The second flow path allows the low-temperature water to flow without passing through the heating unit. The flow detector is arranged in the first flow path or the second flow path. The control valve is connected to the first flow path and the second flow path, and controls the flow of the first flow path and the second flow path. In order to control the outlet hot water temperature after the low-temperature water and the high-temperature water are mixed to the hot water supply set temperature, the control device sets the control value of the control valve and the heating amount based on the heating unit. The control valve is configured as follows: relative to the change of the control value, there is a first interval in which the flow ratio of the first flow path and the second flow path changes without affecting the total flow of the first flow path and the second flow path, and a second interval in which the flow ratio is fixed and the total flow is reduced on the other hand. The control device sets the control value of the control valve in the second interval so that the total flow rate becomes less than the limit flow rate, and controls the heating amount of the heating unit so that the outlet heated water temperature is controlled to the hot water supply set temperature, when the total flow rate obtained based on the flow rate detected by the flow detector is greater than the limit flow rate set corresponding to the maximum heating amount of the heating unit. On the other hand, when the total flow rate obtained based on the flow rate detected by the flow detector is less than the limit flow rate, the heating amount of the heating unit is controlled so that the temperature of the high-temperature water is controlled to the tank set temperature, and the control value of the control valve is set in the first interval corresponding to the flow rate ratio for controlling the outlet heated water temperature to the hot water supply set temperature. The tank set temperature is set to have a flow rate region in which the tank set temperature decreases as the total flow rate increases and approaches the limit flow rate.

[0015] [Effects of the Invention]

[0016] According to the present invention, it is possible to improve the temperature control accuracy in a bypass hybrid hot water supply device using a control valve having a region where the flow rate ratio does not change with respect to a change in a control value. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic structural diagram of a hot water supply device according to an embodiment of the present invention.

[0018] Figure 2 It is applied to Figure 1 A conceptual diagram for explaining the input / output of a mixing valve of a hot water supply device.

[0019] Figure 3 It means it is applied to Figure 1 Conceptual diagram of the characteristics of a mixing valve of a hot water supply device.

[0020] Figure 4 This is a flowchart for explaining a control process of a mixing valve in the hot water supply device according to the embodiment of the present invention.

[0021] Figure 5 This is a flowchart for explaining combustion control of a heating unit in the hot water supply device according to the embodiment of the present invention.

[0022] Figure 6 This is a conceptual diagram for explaining a comparative example of setting the tank body set temperature.

[0023] Figure 7 This is a conceptual diagram for explaining an example of setting the tank body set temperature according to the embodiment of the present invention.

[0024] [Explanation of Symbols]

[0025] 5: Tank

[0026] 10: Heat exchanger

[0027] 15: Exhaust path

[0028] 30: Combustion Burner

[0029] 31: Gas supply pipe

[0030] 32: Original gas solenoid valve

[0031] 33: Gas proportional valve

[0032] 35a~35c: Capacity switching valve

[0033] 40: Air supply fan

[0034] 45: Speed ​​sensor

[0035] 50: Water inlet

[0036] 55: Tank piping

[0037] 60: Bypass piping

[0038] 70: Hot water outlet

[0039] 75: Confluence Point

[0040] 80: Mixing valve

[0041] 81: First port

[0042] 82: Second port

[0043] 83: Third port

[0044] 91: Temperature control area

[0045] 92: Flow control area

[0046] 100: Hot water supply device

[0047] 101: First traffic area

[0048] 102: Second traffic area

[0049] 110, 120, 130: Temperature sensor

[0050] 150: Flow sensor

[0051] 200: Controller

[0052] Q1, Q2: Traffic

[0053] Q1max: Maximum flow rate of the tank

[0054] Qlm: Limit traffic

[0055] Qmax: Maximum flow rate

[0056] Qst: target total flow

[0057] Qt: Total flow

[0058] Qx: Boundary traffic

[0059] T1: Constant value

[0060] T2r: Calculation temperature (tank temperature)

[0061] Tb: Tank temperature

[0062] Tb*: Tank set temperature

[0063] Th: outlet water temperature

[0064] Tr: Hot water supply set temperature

[0065] Tw: Inlet water temperature

[0066] X: Opening control value (mixing valve)

[0067] X1: minimum value (opening control value)

[0068] X2: Maximum value (opening control value)

[0069] Xt: Boundary value (opening control value)

[0070] k: flow ratio

[0071] kst: target flow ratio DETAILED DESCRIPTION

[0072] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, 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.

[0073] Figure 1 It is a schematic configuration diagram of a hot water supply device 100 according to an embodiment of the present invention.

[0074] Reference Figure 1 The hot water supply device 100 includes: a combustion tank body (hereinafter also referred to as a "tank body") 5 that accommodates a heat exchanger 10 and a combustion burner 30, an air supply fan 40, a water inlet line 50, a tank body piping 55, a bypass piping 60, a hot water outlet line 70, a mixing valve 80, and a controller 200.

[0075] The water inlet passage 50 is connected to the tank pipe 55 and the bypass pipe 60 via a mixing valve 80. Low-temperature water such as tap water is supplied to the water inlet passage 50. The low-temperature water in the water inlet passage 50 is distributed to the tank pipe 55 and the bypass pipe 60 via the mixing valve 80. In the present embodiment, the "control valve" for controlling the flow ratio of high-temperature water and low-temperature water in the bypass mixing method is configured using the mixing valve 80 having the characteristics described below.

[0076] The tank pipe 55 flows low-temperature water to the heat exchanger 10. The low-temperature water introduced from the water inlet passage 50 to the tank pipe 55 is heated by the heat generated by the burner 30 through the heat exchanger 10. Thus, the heat exchanger 10 outputs high-temperature water.

[0077] A raw gas solenoid valve 32, a gas proportional valve 33, and capacity switching valves 35a to 35c are arranged in a gas supply pipe 31 to the combustion burner 30. The raw 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 of the gas supply pipe 31 is controlled according to the opening degree of the gas proportional valve 33.

[0078] The capacity switching valves 35a to 35c are controlled to open and close in order to switch the number of burners to which the fuel gas is supplied among the plurality of combustion burners 30. The amount of heat generated in the tank 5 is proportional to the amount of gas supplied from the combustion burners 30 as a whole, which is determined by the combination of the number of burners and the gas flow rate. Therefore, a setting diagram that determines the combination of the opening and closing patterns (the number of burners) of the capacity switching valves 35a to 35c and the opening degree (gas flow rate) of the gas proportional valve 33 can be prepared in advance in accordance with the heating amount required by the combustion burners 30.

[0079] In the tank 5, the fuel gas output from the combustion burner 30 is mixed with the combustion air from the air supply fan 40. The air supply amount based on the air supply fan 40 is controlled so that the air-fuel ratio with the supply gas amount from the combustion burner 30 as a whole becomes a predetermined value (for example, an ideal air-fuel ratio). The air supply amount of the air supply fan 40 is proportional to the fan speed, so the speed of the air supply fan 40 is controlled according to the target speed set according to the change in the supply gas amount. The air supply fan 40 is provided with a speed sensor 45 for detecting the fan speed.

[0080] The mixed gas of the fuel gas and the combustion air is ignited by an ignition device (not shown), whereby the fuel gas burns to generate a flame. The combustion heat generated by the flame from the combustion burner 30 is supplied to the heat exchanger 10 in the tank 5 .

[0081] The high-temperature water heated by the heat exchanger 10 is output toward the hot water outlet path 70. An exhaust path 15 for discharging the combustion exhaust gas after heat exchange is provided on the downstream side of the flow direction of the combustion gas of the tank 5. In addition, the heat exchanger 10 may also be configured to include both a primary heat exchanger and a secondary heat exchanger.

[0082] The bypass pipe 60 and the tank pipe 55 are connected at a confluence point 75. Warm water of an appropriate temperature adjusted by mixing high-temperature water from the tank pipe 55 and low-temperature water from the bypass pipe 60 is supplied to the hot water outlet pipe 70 on the downstream side of the confluence point 75. The warm water in the hot water outlet pipe 70 is supplied to a predetermined hot water supply location such as a hot water supply tap (not shown) in a kitchen or bathroom, or a hot water injection circuit (not shown) for a bathtub.

[0083] Thus, the hot water supply device 100 has a structure of a so-called bypass mixing method in which high-temperature water passing through the heat exchanger 10 is mixed with low-temperature water bypassing the heat exchanger 10 via the mixing valve 80. As described later, the flow rate ratio (mixing ratio) of the high-temperature water and the low-temperature water is controlled by an opening control value (described later) of the mixing valve 80 from the controller 200.

[0084] Therefore, in Figure 1 In the structural example of , the "first flow path" is formed by the tank pipe 55, and the "second flow path" is formed by the bypass pipe 60. Furthermore, the heat exchanger 10 that receives heat from the combustion burner 30 constitutes an embodiment of the "heating unit".

[0085] In addition, hereinafter, the flow rate of the tank pipe 55 (first flow path) is marked as Q1, and the flow rate of the bypass pipe 60 (second flow path) is marked as Q2. In addition, the hot water flow rate from the hot water outlet line 70 is equivalent to the total flow rate Qt of the hot water supply device 100 based on the sum of the flow rate Q1 and the flow rate Q2 (Qt = Q1 + Q2). Each flow rate is a flow rate per unit time, and its unit is, for example, liter / minute.

[0086] The temperature sensor 110 is provided on the tank pipe 55 at the upstream side of the heat exchanger 10 in order to detect the temperature of the low-temperature water. The temperature sensor 110 may be provided on the water inlet passage 50 or the bypass pipe 60.

[0087] The temperature sensor 120 is disposed on the tank pipe 55 at a position downstream of the heat exchanger 10 in order to detect the temperature of the high-temperature water. That is, the temperature sensor 120 is disposed at a position upstream of the confluence point 75. The temperature sensor 130 is disposed in the hot water outlet path 70 at a position downstream of the confluence point 75 in order to detect the temperature of the hot water outlet after the high-temperature water and the low-temperature water are mixed.

[0088] Hereinafter, the temperature detected by the temperature sensor 110 is referred to as the inlet water temperature Tw, the temperature detected by the temperature sensor 120 is referred to as the tank body temperature Tb, and the temperature detected by the temperature sensor 130 is referred to as the outlet hot water temperature Th.

[0089] A flow sensor 150 is further disposed in the tank pipe 55. The flow sensor 150 can be typically constituted by an impeller-type flow sensor. The flow sensor 150 detects a flow rate Q1 of the tank pipe 55. The flow sensor 150 corresponds to an example of a "flow rate detector".

[0090] The controller 200 may be composed of, for example, a microcomputer. The controller 200 receives the detection values ​​obtained by each sensor and the user operation, and generates a control command for each device to control the overall operation of the hot water supply device 100. The user operation includes an on / off command of the operation switch of the hot water supply device 100 and a designation of a hot water supply set temperature Tr corresponding to a target value of the hot water supply temperature.

[0091] When the operation switch of the hot water supply device 100 is turned on, the flow rate Q1 detected by the flow sensor 150 exceeds the minimum operation flow quantity (MOQ), and accordingly, the controller 200 turns on the combustion action of the tank 5. When the combustion action is turned on, the raw gas solenoid valve 32 opens, and the supply of fuel gas to the combustion burner 30 is started, and ignition is performed by the ignition device not shown. Accordingly, the hot water supply operation performed by the hot water supply device 100 is started. During the hot water supply operation, the controller 200 controls the outlet hot water temperature according to the hot water supply set temperature Tr.

[0092] When the operation switch of the hot water supply device 100 is turned off, or when the flow rate Q1 falls below the minimum operating flow rate (MOQ) during the hot water supply operation, the supply of fuel gas to the combustion burner 30 is stopped, thereby ending the hot water supply operation.

[0093] Next, the characteristics of the mixing valve 80 applied to the hot water supply device 100 of the present embodiment will be described in detail.

[0094] like Figure 2 As shown, the mixing valve 80 has a first port 81 connected to the tank pipe 55, a second port 82 connected to the bypass pipe 60, and a third port 83 connected to the water inlet passage 50. The mixing valve 80 is configured to control the opening of one or more valve bodies (not shown) according to the opening control value X from the controller 200, so that the opening area of ​​at least a part of the first port 81, the second port 82, and the third port 83 changes, thereby controlling the flow rate Q1 and the flow rate Q2. For example, the valve body is driven to open and close by a stepping motor (not shown). In this case, the opening control value X is represented by the number of steps of the stepping motor.

[0095] As an example, the opening areas of the first port 81 and the second port 82 are controlled to change according to the opening of the first valve body (not shown), while the sum of the two is maintained at 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 body (not shown).

[0096] The flow rate Q1 of the tank piping 55 varies with the opening area of ​​the first port 81, and the flow rate Q2 of the bypass piping 60 varies with the opening area of ​​the second port 82. On the other hand, since the sum of the opening areas of the first port 81 and the second port 82 is constant, the flow ratio k (defined as k=Q2 / Q1) of the flow rate Q1 and the flow rate Q2 varies according to the opening degree of the first valve body.

[0097] 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) varies with the opening area of ​​the third port 83 according to the opening degree of the second valve body.

[0098] Figure 3 2 shows a characteristic diagram of the mixing valve 80 with respect to the opening control value X.

[0099] like Figure 3 As shown, the mixing valve 80 is configured such that, with respect to the opening control value X that changes between the minimum value X1 and the maximum value X2, there is a first interval (X=X1-Xt) in which the flow ratio k changes without affecting the total flow Qt, and a second interval (X=Xt-X2) in which the total flow Qt changes when the flow ratio k is set to a constant value. Hereinafter, the first interval is also referred to as a "temperature control area 91", and the second interval is also referred to as a "flow control area 92".

[0100] The total flow rate Qt is maintained at the maximum flow rate Qmax in the temperature control region 91 (X=X1-Xt), and is controlled to decrease from the maximum flow rate Qmax to the minimum flow rate Qmin in the flow rate control region 92 (X=Xt-X2) according to the increase of the opening control value X.

[0101] In contrast, the flow ratio k is controlled in the temperature control area 91 (X=X1~Xt) to gradually decrease from the maximum value kmax to the minimum value kmin according to the increase of the opening control value X, and on the other hand, it is maintained at the minimum value kmin under X=Xt in the flow control area 92 (X=Xt~X2).

[0102] For example, the mixing valve 80 is configured such that, in the temperature control region 91, the opening control value X increases from the minimum value X1 to the boundary value Xt, and accordingly, the opening area of ​​the first port 81 gradually increases, while the opening area of ​​the second port 82 gradually decreases, so that the opening areas of the first port 81 and the second port 82 change in conjunction with each other, and the opening area of ​​the third port 83 is maintained at the maximum value in the temperature control region 91 independently of the opening control value X. In this way, Figure 3The flow rate ratio k and the total flow rate Qt in the temperature control area 91 shown are characteristics relative to the opening control value X. In addition, the maximum flow rate Qmax is determined by the pressure of the low-temperature water introduced into the water supply path 50 (for example, the water pressure of the water supply pipe) and the opening of the hot water supply tap (not shown) at the hot water supply destination.

[0103] In addition, the mixing valve 80 is configured such that, in the flow control region 92, the opening control value X increases from the boundary value Xt to the maximum value X2, and accordingly, 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 at the state when X=Xt. Figure 3 The flow rate ratio k and the total flow rate Qt in the flow rate control area 92 shown in FIG. Figure 3 The flow rate Q1 (high temperature water) and the flow rate Q2 (low temperature water) are controlled based on the flow rate ratio (Q2 / Q1) and the total flow rate (Q1+Q2) characteristics shown.

[0104] In addition, the flow ratio kmin can be set to generate a flow in the bypass piping 60 even in the flow control area 92 (Q2>0, kmin>0), or the flow ratio kmin=0 (i.e., Q2=0) in the flow control area 92 can be set by fully closing the second port 82 under X=X2.

[0105] In addition, 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 making the third port 83 in a fully closed state. On the other hand, when X=X2, Qmin>0 can also be set by not making the third port 83 in a fully closed state. However, as described above, when the flow rate Q1 is lower than the minimum operating flow rate (MOQ), the combustion in the combustion burner 30 stops.

[0106] Therefore, the hot water supply device 100 can control the outlet heated water temperature Th to the hot water supply set temperature Tr by adjusting the flow ratio k using the opening control value X of the mixing valve 80 in the temperature control area 91. When the maximum heating amount Pmax when the heat generated by the "heating part" in the hot water supply device 100, that is, the combustion burner 30 is set to the maximum value (for example, the maximum gas flow rate and combustion in all burners) is greater than the required heating amount Prq (Prq = Qt · ΔT) according to the product of the total flow rate Qt and the temperature increase amount ΔT = Tr-Tw (Prq ≦ Pmax), it can be understood that the outlet heated water temperature can be controlled by adjusting the flow ratio k in the temperature control area 91.

[0107] On the other hand, if the required heating amount Prq is greater than the maximum heating amount Pmax (Prq>Pmax), the outlet heated water temperature Th cannot be raised to the hot water supply set temperature Tr unless the total flow rate Qt is reduced from the maximum flow rate Qmax. Therefore, it is necessary to control the outlet heated water temperature by adjusting the total flow rate Qt in the flow control area 92.

[0108] The relationship between the required heating amount Prq and the maximum heating amount Pmax can also be expressed by the total flow rate Qt. Here, if the maximum value of the total flow rate Qt that can increase the inlet water temperature Tw to the hot water supply setting temperature Tr when the maximum heating amount Pmax is generated is defined as the limiting flow rate Qlm, the limiting flow rate Qlm can be expressed by the following formula (1) using the thermal efficiency η (η≦1.0). In addition, in order to simplify the description below, η=1.0 is used for processing.

[0109] Qlm=η·Pmax / (Tr-Tw)…(1)

[0110] Therefore, it can be determined that when the limit flow rate Qlm is compared with the total flow rate Qt, and when Qt≦Qlm, the outlet heated water temperature control is performed based on the adjustment of the flow rate ratio k in the temperature control area 91, and on the other hand, when Qt>Qlm, the outlet heated water temperature control is performed based on the adjustment of the total flow rate Qt in the flow control area 92 (Qt≦Qlm). That is, it can be understood that the determination by comparing the limit flow rate Qlm and the total flow rate Qt is equivalent to the determination by comparing the required heating amount Prq and the maximum heating amount Pmax.

[0111] In addition, when the flow rate Q1 of the tank pipe 55 becomes the upper limit flow rate (tank maximum flow rate Q1max) in terms of durability performance of the heat exchanger 10, the mixing valve 80 can be operated in the flow control area 92, and a flow control for setting Q1≦Q1max can be further combined. In this case, when the flow value converted from the tank maximum flow rate Q1max to the total flow rate using the flow ratio k is smaller than the flow value obtained by the above formula (1), the flow value converted from the tank maximum flow rate Q1max is set as the limit flow rate Qlm, so that the flow control limited to Q1≦Q1max can be performed.

[0112] Here, the relationship of the following equation (2) holds true among the flow rate Q1 of the tank pipe 55, the flow rate Q2 of the bypass pipe 60, the tank temperature Tb, the inlet water temperature Tw, and the outlet hot water temperature Th.

[0113] Q2·(Th-Tw)=Q1·(Tb-Th)…(2)

[0114] According to formula (2), the flow ratio k (k=Q2 / Q1) can be expressed by formula (3) according to the tank temperature Tb, the inlet water temperature Tw and the outlet hot water temperature Th.

[0115] k=Q2 / Q1=(Tb-Th) / (Th-Tw)…(3)

[0116] Therefore, the flow rate ratio k* for controlling the outlet heated water temperature Th to the hot water supply set temperature Tr can be calculated by the following equation (4) by replacing the outlet heated water temperature Th with the hot water supply set temperature Tr in equation (2).

[0117] k*=Q2 / Q1=(Tb-Tr) / (Tr-Tw)…(4)

[0118] Theoretically, by setting the flow rate ratio by the mixing valve 80 according to the flow rate ratio k* calculated by the formula (4), the outlet hot water temperature Th can be controlled to the hot water supply set temperature Tr.

[0119] On the other hand, by substituting the detected temperatures of the temperature sensors 110, 120, and 130 into the equation (3) during the hot water supply operation, the actual flow rate ratio k calculated by reverse calculation from the temperature performance value can be calculated successively.

[0120] Hereinafter, the flow rate ratio obtained in this manner is referred to as an actual flow rate ratio ktm.

[0121] For example, by measuring the actual flow rate ratio ktm of the mixing valve 80 with respect to the opening control value X based on the results of a previous actual machine test, etc., it is possible to obtain the correspondence relationship between the opening control value X (number of steps) and the flow rate ratio k in the mixing valve 80. Thus, for the mixing valve 80, the correspondence relationship serving as a reference between the opening control value X and the flow rate ratio k can be predetermined as a reference characteristic line (Xk) regarding the flow rate ratio.

[0122] Therefore, the controller 200 can perform outlet hot water temperature control by reversely calculating the opening control value X based on the flow rate ratio k* calculated by equation (4) to control the mixing valve 80.

[0123] Similarly, by using the flow detection value obtained by the flow sensor 150 when the opening control value X of the mixing valve 80 is changed in the flow control area 92, the correspondence between the opening control value X of the mixing valve 80 and the total flow Qt, that is, the reference characteristic line (X-Qt) regarding the total flow Qt in the flow control area 92 can be predetermined based on the results of actual machine tests, etc.

[0124] Figure 4 Yes Figure 1 A flowchart for explaining a control process of a mixing valve in a hot water supply device. Figure 4The process of the flowchart shown in FIG. 1 may be periodically executed by the controller 200 during the hot water supply operation. Figure 4 Although the description is omitted, the controller 200 may execute Figure 4 The detection values ​​(Tw, Tb, Tw, Q1) obtained by each sensor are acquired in each control cycle of the processing shown.

[0125] Reference Figure 4 The controller 200 calculates the total flow rate Qt according to the flow rate Q1 detected by the flow sensor 150 through step (hereinafter also simply marked as "S") 100. At this time, it can be calculated according to the current opening control value X of the mixing valve 80 using the flow ratio k calculated inversely according to the reference characteristic line (Xk) according to equation (5).

[0126] Qt=Q1+Q2=(1+k)·Q1…(5)

[0127] The controller 200 sets the limited flow rate Qlm according to equation (1) by using the detected value of the inlet water temperature Tw (temperature sensor 110), the hot water supply set temperature Tr, and the maximum heating amount Pmax as the specification value of the hot water supply device 100 through S200. Alternatively, in S200, as described above, the limited flow rate Qlm may be further combined with a flow control mode that limits the limited flow rate Qlm to less than the maximum flow rate Q1max of the tank to set the limited flow rate Qlm.

[0128] The controller 200 compares the total flow rate Qt calculated in S100 with the limit flow rate Qlm calculated in S200 in S300. When the total flow rate Qt is less than the limit flow rate Qlm (when S300 is determined to be YES), the controller 200 advances the process to S400, and in the control cycle, sets the opening control value X of the mixing valve 80 to the temperature control area 91 ( Figure 3 ) Temperature control performed within.

[0129] On the other hand, when the total flow rate Qt is greater than the limit flow rate Qlm (at the time of the NO determination in S300), the controller 200 advances the process to S500, and in the control cycle, the opening control value X of the mixing valve 80 is set to the flow control area 92 ( Figure 3 ) within the flow control.

[0130] When the controller 200 performs temperature control (S400), the target flow ratio kst, which is a target flow ratio k, is calculated according to the flow ratio k* in the formula (4) by using the detected values ​​of the inlet water temperature Tw and the tank temperature Tb in the control cycle and the hot water supply set temperature Tr through S410. That is, kst is set to k*=(Tb-Tr) / (Tr-Tw).

[0131] In S420, the controller 200 calculates the flow ratio k[i] in this control cycle according to the target flow ratio kst calculated in S410. In S420, the target flow ratio kst may be directly set as the flow ratio k[i], or the flow ratio k[i] may be set by further reflecting a feedback control term based on the deviation between the outlet hot water temperature Th and the hot water supply set temperature Tr.

[0132] Furthermore, the controller 200 sets the opening control value X[i] of the mixing valve 80 in the i-th control cycle within the temperature control area 91 according to the flow ratio k[i] calculated in S420 in accordance with the reference characteristic line (Xk) regarding the flow ratio k through S430.

[0133] On the other hand, when the controller 200 performs flow control (S500), it sets the target total flow rate Qst under flow control through S510. The target total flow rate Qst in S510 is set to be less than the limit flow rate Qlm. Thus, the heating amount based on the heating unit (combustion burner 30) can be set within a range below the maximum heating amount Pmax. In addition, by reflecting the maximum flow rate Q1max of the tank body to set the limit flow rate Qlm, the flow rate ratio kmin ( Figure 3 ), limit the flow rate Q1 to below the maximum flow rate Q1max of the tank.

[0134] The controller 200 calculates the total flow rate Qt[i] in this control cycle according to the target total flow rate Qst set in S510 in S520. For example, in S520, the target total flow rate Qst may be directly set as the total flow rate Qt[i].

[0135] Furthermore, the controller 200 sets the opening control value X[i] of the mixing valve 80 in the i-th control cycle within the flow control area 92 according to the reference characteristic line (X-Qt) regarding the total flow Qt and the total flow Qt[i] calculated in S520 through S530.

[0136] The hot water temperature is controlled by Figure 4 The control of the mixing valve 80 shown is performed in combination with the control based on the heating amount of the heating unit (combustion burner 30).

[0137] Figure 5 2 is a flowchart for explaining the combustion control of the combustion burner in the hot water supply device 100.

[0138] Reference Figure 5 , the controller 200 branches the combustion control process according to which of the temperature control and the flow control is performed by the mixing valve (HV) 80 through S600. Figure 4 The S300 performs similarly.

[0139] When the controller 200 performs temperature control (when the judgment is yes in S600), the target temperature of the tank body temperature Tb, that is, the tank body setting temperature Tb* is set in S610. Then, in S620, the combustion control is performed to adjust the heating amount by the combustion burner 30 so that the tank body temperature Tb (temperature sensor 120) is the tank body setting temperature Tb*.

[0140] For example, in S620, the heating amount based on the combustion burner 30 can be set according to the product of the temperature difference between the tank setting temperature Tb* and the inlet water temperature Tw and the total flow rate Qt (S100). Alternatively, the heating amount based on the combustion burner 30 can be set by further reflecting a feedback control item for compensating for the deviation between the tank temperature Tb (temperature sensor 120) and the tank setting temperature Tb*.

[0141] As described above, the amount of heating by the combustion burner 30 can be adjusted by a combination of the opening and closing patterns (the number of burners) of the capacity switching valves 35 a to 35 c and the opening degree (gas flow rate) of the gas proportional valve 33 .

[0142] On the other hand, when the controller 200 performs flow control (when the judgment of "No" is made in S600), the controller 200 performs combustion control in S630 so as to adjust the heating amount (i.e., the amount of gas) by the combustion burner 30 according to the comparison between the outlet heated water temperature Th (temperature sensor 130) and the hot water supply setting temperature Tr. Thus, even when the flow rate ratio k by the mixing valve 80 is constant, the temperature control for making the outlet heated water temperature Th equal to the hot water supply setting temperature Tr can be performed.

[0143] Furthermore, as described above, if the flow rate limit Qlm is set so that the flow rate Q1 becomes less than the maximum flow rate Q1max of the tank, then in the flow rate control area 92, the flow rate ratio kmin ( Figure 3 ) is performed so that the flow rate is controlled in a manner such that Q1≦Q1max, and at the same time, within the range in which the heating amount in the combustion burner 30 is below the maximum heating amount Pmax, the heating amount based on the combustion burner 30 is controlled in a manner such that the hot water outlet temperature Th becomes the hot water supply set temperature Tr.

[0144] Next, setting of the tank set temperature Tb* during temperature control of the mixing valve 80 will be described. Figure 6 A comparative example of setting the tank body set temperature Tb* is shown in FIG. Figure 7 2 shows a setting example of the tank body set temperature Tb* according to the present embodiment.

[0145] When the tank body temperature Tb is examined, if the tank body temperature Tb is low, condensation is likely to occur on the surface of the heat exchanger 10. In addition, if it is assumed that the outlet heated water temperature Th is maintained when the flow rate increases, it can be understood that the control responsiveness is higher when the outlet heated water temperature Th is maintained by adjusting the flow rate ratio k than when the outlet heated water temperature Th is maintained by increasing the heating amount.

[0146] Therefore, when the mixing valve 80 operates in the temperature control region 91 (temperature control), the tank temperature Tb is set high and the outlet heated water temperature Th is controlled to the hot water supply set temperature Tr by adjusting the flow ratio k.

[0147] On the other hand, when the mixing valve 80 operates in the flow control region 92 (temperature control), when the flow ratio k is fixed at Figure 3 In the case of kmin in the combustion burner 30, the outlet heated water temperature Th is controlled to the hot water supply set temperature Tr along with the adjustment of the heating amount in the combustion burner 30. Therefore, the tank temperature Tb is determined by the outlet heated water temperature Th and the flow rate ratio kmin, and therefore is not directly controlled by the combustion control.

[0148] Therefore, in Figure 6 In the comparative example, when the temperature is controlled such that Qt≦Qlm, the tank set temperature Tb* is set to a temperature T1 obtained by adding a fixed value α (e.g., α=15 to 20 [°C]) to the hot water supply set temperature Tr (T1=Tr+α). In this case, the tank set temperature Tb* is set to a constant value (T1) relative to the change in the total flow rate Qt.

[0149] In contrast, in the flow control of Qt>Qlm, the tank set temperature Tb* is not set, and the actual tank temperature Tb becomes the temperature T2 determined by the outlet heated water temperature Th and the flow rate ratio kmin in the flow control region 92 (Tb=T2).

[0150] However, in accordance with Figure 6 In the case where the tank set temperature Tb* is set during temperature control, when the temperature control is switched to the flow control according to the increase of the total flow rate Qt, the following problem may occur in the control of the outlet heated water temperature Th.

[0151] During temperature control, as described in equations (2) and (3), the flow rate ratio k does not directly depend on the total flow rate Qt, but is controlled by the relationship between the tank temperature Tb (tank set temperature Tb*), the outlet hot water temperature Th (hot water supply set temperature Tr), and the inlet water temperature Tw. Therefore, there is a possibility that the difference between the flow rate ratio k during temperature control and the flow rate ratio (minimum value kmin) in the flow rate control area 92 is relatively large.

[0152] In this state, if the temperature control is switched to the flow control directly, the outlet heated water temperature Th may be higher than the hot water supply set temperature Tr due to the difference between the tank temperature Tb controlled to the tank set temperature Tb* and the tank temperature (T2) during the flow control. Therefore, the total flow rate Qt cannot be limited immediately, and the flow control for limiting the total flow rate Qt needs to be started after the transition period is set to continue the temperature control based on the flow rate ratio k and adjust the heating amount of the combustion burner 30 to reduce the tank temperature Tb. During this transition period, a total flow rate Qt greater than the limited flow rate Qlm is generated, and the temperature control accuracy is temporarily reduced due to the reduction of the outlet heated water temperature Th.

[0153] In contrast, in the setting example of the tank set temperature according to an embodiment of the present invention, a flow area in which the tank set temperature Tb* decreases as the total flow rate Qt increases is set near the limiting flow rate Qlm in the flow area where Qt<Qlm is applied to temperature control.

[0154] like Figure 7 As shown, by multiplying the limiting flow Qlm by a coefficient β (0<β<1.0), the boundary flow Qx is set, and in the first flow region 101 where Qt≦Qx, the tank setting temperature Tb* is Figure 6 Similarly to the comparative example of , Tb*=T1 (T1=Tr+α) is set. That is, in the first flow rate region 101, the tank body set temperature Tb* is constant with respect to changes in the total flow rate Qt.

[0155] On the other hand, in the second flow rate region 102 where Qx<Qt≦Qlm, the tank setting temperature Tb* is set to decrease from the constant value T1 as the total flow rate Qt increases.

[0156] For example, the calculated temperature T2r of the tank temperature Tb during flow control can be calculated using the hot water supply set temperature Tr and the flow ratio kmin in the flow control area 92. Therefore, when Qt=Qx, Tb*=T1, and when Qt=Qlm, Qb*=T2r, and between Qx<Qt<Qlm, the tank set temperature Tb* in the second flow area 102 can be set to decrease at a certain rate relative to the increase of the total flow Qt.

[0157] The calculated temperature T2r can be set, for example, according to the formula (7) in which the flow rate Q1, flow rate Q2, hot water supply setting temperature Tr, and water inlet temperature Tw (detected temperature) are modified and the flow rate ratio k (k = Q2 / Q1) = kmin (flow rate control area 92) is set. The calculated temperature T2r corresponds to the "lower limit setting value" of the tank setting temperature Tb*.

[0158] Q1·T2r+Q2·Tw=(Q1+Q2)·Tr…(6)

[0159] T2r=Tr+kmin·(Tr-Tw)…(7)

[0160] That is, in this embodiment, Figure 7 implement Figure 5 The tank body set temperature Tb* is set during the temperature control in S610. Figure 7 The boundary flow rate Qx in can also be set according to the difference of the predetermined flow rate from the limiting flow rate Qlm. If so, the rate at which the tank set temperature Tb* changes relative to the increase of the total flow rate Qt can be fixed. In any case, the first flow rate region 101 (Qt≦Qx) is located at a lower flow rate side than the second flow rate region 102 (Qx<Qt≦Qlm).

[0161] Therefore, in the hot water supply device of this embodiment, when the temperature control is switched to the flow control as the total flow rate Qt increases, the tank body temperature Tb during the temperature control before the switch and the tank body temperature Tb after the switch to the flow control (equivalent to Figure 6 As a result, according to the increase of total flow rate Qt, no Figure 6 During the "transfer period" described in the above, the flow control for limiting the total flow rate Qt to below the limit flow rate Qlm can be started. Therefore, the temperature control accuracy can be improved by suppressing the temporary decrease in temperature control accuracy when switching from temperature control to flow control.

[0162] In addition, Figure 1 In the embodiment, the flow sensor 150 is arranged in the tank pipe 55 to detect the flow rate Q1, but the flow sensor 150 is arranged in the bypass pipe 60 to detect the flow rate Q2. Figure 4 and Figure 5 Alternatively, in a configuration where the flow sensor 150 is disposed in the water intake passage 50 and detects the total flow rate Qt (Q1+Q2), the same control process can be applied by calculating the flow rates Q1 and Q2 using the flow rate ratio k.

[0163] In addition, Figure 1 An example is shown in which the heat source of the "heating section" is the combustion heat of a gas fuel, but the fuel is not limited to gas. The hot water temperature control of this embodiment can be applied to a hot water supply device in which the "heating section" is composed of a mechanism that generates combustion heat of any fuel.

[0164] In addition, in the present embodiment, the configuration example of controlling the distribution ratio of low-temperature water from the water inlet 50 to the tank pipe 55 and the bypass pipe 60 by connecting the mixing valve 80 between the water inlet 50 and the tank pipe 55 and the bypass pipe 60 is described, but the mixing valve 80 may be disposed at the confluence point 75 and connected between the hot water outlet 70 and the tank pipe 55 and the bypass pipe 60. In this case, Figure 2 The confluence point 75 of the third port 83 is connected to the hot water outlet line 70, and the flow directions at each port are opposite. Figure 3 The mixing ratio of the high temperature water in the tank pipe 55 and the low temperature water in the bypass pipe 60 is controlled by controlling the flow rate ratio (Q2 / Q1) and the flow rate Q1 and the flow rate Q2 of the total flow rate (Q1+Q2) shown.

[0165] The embodiments disclosed this time should be considered as illustrative in all aspects and not restrictive. The scope of the present invention is indicated by the claims rather than the description above, and is intended to include all modifications within the meaning and scope equivalent to the claims.

Claims

1. A hot water supply device for mixing low-temperature water with high-temperature water, the hot water supply device comprising: A heating unit, heating the low-temperature water to output high-temperature water; a first flow path, for allowing the low-temperature water to flow toward the heating unit; a second flow path for circulating the low-temperature water without passing through the heating unit; a flow detector, disposed in the first flow path or the second flow path; a control valve connected to the first flow path and the second flow path, and used to control the flow of the first flow path and the second flow path; as well as a control device for setting a control value of the control valve and a heating amount based on the heating unit in order to control the outlet hot water temperature after the low-temperature water and the high-temperature water are mixed to a hot water supply set temperature; The control valve is configured such that, with respect to a change in the control value, there is a first interval in which the flow ratio between the first flow path and the second flow path changes without affecting the total flow of the first flow path and the second flow path, and a second interval in which the flow ratio is fixed while the total flow decreases. The control device When the total flow rate obtained based on the flow rate detected by the flow detector is greater than the limiting flow rate set corresponding to the maximum heating amount of the heating unit, the control value of the control valve is set within the second interval so that the total flow rate becomes less than the limiting flow rate, and the heating amount of the heating unit is controlled so that the outlet heated water temperature is controlled to the hot water supply set temperature. On the other hand, When the total flow rate obtained based on the flow rate detected by the flow detector is less than the limit flow rate, the heating amount of the heating unit is controlled in such a manner that the temperature of the high-temperature water is controlled to be the tank set temperature, and the control value of the control valve is set within the first interval corresponding to the flow rate ratio for controlling the outlet heated water temperature to be the hot water supply set temperature, and The tank set temperature is set so that there is a flow rate region in which the tank set temperature decreases as the total flow rate increases and approaches the limit flow rate.

2. The hot water supply device according to claim 1, wherein: The tank set temperature is set to a certain value higher than the hot water supply set temperature in a first flow area that is closer to the lower flow side than the boundary flow that is set to be lower than the limiting flow, and on the other hand, in a second flow area between the boundary flow and the limiting flow, the set temperature decreases from the certain value as the total flow increases.

3. The hot water supply device according to claim 2, wherein: The tank set temperature set in the second flow area is set as follows: it gradually decreases from the certain value to a lower limit set value as the total flow increases, and the lower limit set value corresponds to the temperature of the high-temperature water used to make the outlet heated water temperature the hot water supply set temperature at the flow ratio in the second interval of the control valve.

4. The hot water supply device according to claim 2, wherein: The certain value is set according to the sum of the hot water supply set temperature and a predetermined fixed value.

5. The hot water supply device according to any one of claims 1 to 4, wherein: The limiting flow is set according to the second value when the second value is smaller than the first value, the second value corresponds to the total flow when the flow of the first flow path becomes the allowable maximum flow of the heating unit at the flow ratio in the second interval of the control valve, and the first value corresponds to the total flow that can make the outlet heated water temperature the hot water supply set temperature when the maximum heating amount of the heating unit is generated.

Images