warm water heat source machine

Abstract

This improves the hot water supply capacity of a hot water heat source unit with a configuration in which two tanks are connected in series, in accordance with the user-set temperature. [Solution] An upstream sub-boiler 10S and a downstream main boiler 10M are connected in series via piping 8 between the inlet pipe 3 and the outlet pipe 4. In the sub-boiler 10S, temperature control is performed by the controller 100S turning the burner 20S on and off based on a comparison between the temperature detected by the temperature sensor 110S and a first control target temperature. In the main boiler 10M, temperature control is performed by the controller 100M turning the burner 20M on and off based on a comparison between the temperature detected by the temperature sensor 110M and a second control target temperature. The first control target temperature of the sub-boiler 10S and the second control target temperature of the main boiler 10M are set to be equivalent to the user's hot water setting temperature.

Description

Technical Field

[0006]

[0001] The present invention relates to a hot water heat source machine using fuel combustion heat.

Background Art

[0002] In order to achieve a large-capacity hot water supply or hot water heating, a hot water heat source machine (typically, a boiler) having a configuration in which two cans each including a heating element are connected in series is used. In such a configuration, in each of the two cans, since on-off control of the heating element is possible, there is a degree of freedom in temperature control for controlling the hot water outlet temperature from the downstream can.

[0003] Japanese Patent No. 2926284 (Patent Document 1) describes an electric water heater configured by connecting a plurality of hot water storage tanks each provided with a heating element at the bottom in series. In the electric water heater of Patent Document 1, during the late-night power time zone, after turning on the heating element in response to the arrival of the power-on start time, when the measured hot water temperature of each hot water storage tank rises above the set temperature, temperature control for turning off the heating element of the hot water storage tank is performed for each hot water storage tank.

[0004] <​​​​​​​​​​​​​​​​​​​​​​​However, the water temperature control described in Patent Document 1 is based on the premise of heating by electricity and basically heats the low-temperature water stored in each hot water storage tank to a set temperature when no flow rate is being generated by the hot water supply, and is not intended to handle situations where a flow rate is being generated.

[0007] In response to this, there is a need for boilers (hot water heat sources) that can handle continuous hot water supply at hot water flow rates below the rated flow rate. Such hot water heat sources can achieve high capacity by heating the incoming low-temperature water to a set temperature through stepwise heating of the upstream and downstream boilers using the heat of fuel combustion. However, it is difficult to apply the water temperature control described in Patent Document 1 to the temperature control of each boiler in such a configuration.

[0008] The present invention was made to solve these problems, and the object of the present invention is to efficiently improve the hot water supply capacity through temperature control in each boiler in a hot water heat source unit configured to connect two boilers in series, each boiler containing a heating element due to the heat of fuel combustion. [Means for solving the problem]

[0009] In one aspect of the present invention, a hot water heat source is provided. It comprises an upstream boiler, a downstream boiler, and inter-boiler piping. The upstream boiler has a first water channel connected to an inlet pipe. The downstream boiler has a second water channel connected to a hot water outlet pipe. The inter-boiler piping connects the first and second water channels to connect the upstream and downstream boilers in series between the inlet and hot water outlet pipes. Each of the upstream and downstream boilers includes a combustion mechanism that generates heat from fuel combustion, a heat exchanger, and a controller. The heat exchanger is configured to heat the fluid in the first or second water channel using the heat generated by the combustion mechanism. The controller is configured to control the on / off of combustion by the combustion mechanism to generate a predetermined amount of heat. The controller of the upstream boiler is configured to control the on / off of combustion by the combustion mechanism of the upstream boiler based on a comparison of the temperature detected by a first temperature sensor provided in the first water channel with a first control target temperature. The controller for the downstream boiler is configured to control the on / off state of combustion in the combustion mechanism of the downstream boiler based on a comparison between the temperature detected by a second temperature sensor located in the second water flow path and a second control target temperature. The first and second control target temperatures are set to be equivalent to the set temperature of the hot water supplied from the hot water outlet pipe. [Effects of the Invention]

[0010] According to the present invention, in a hot water heat source unit configured by connecting two boilers including a combustion mechanism in series, the hot water supply capacity corresponding to the user's set temperature can be improved by setting the first control target temperature in the upstream boiler to be the same as the hot water supply set temperature, similar to the second control target temperature in the downstream boiler. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram illustrating an example of the configuration of a hot water heat source unit according to this embodiment. [Figure 2] This is a block diagram illustrating the communication configuration of the remote control and the controllers for each individual tank. [Figure 3] This is a conceptual diagram illustrating temperature control in each tank. [Figure 4]This is a conceptual diagram illustrating the operation pattern of the can under temperature control shown in Figure 3. [Figure 5] This diagram illustrates an example of setting the target temperature for each container in temperature control. [Figure 6] This diagram illustrates a comparative example and an example of temperature control according to this embodiment. [Figure 7] This is a flowchart illustrating the control of changing the target temperature for each individual tank. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, the same or corresponding parts in the drawings will be denoted by the same reference numerals, and their descriptions will not be repeated in principle.

[0013] <Equipment configuration> Figure 1 is a schematic diagram illustrating an example of the configuration of the hot water heat source unit 1 according to this embodiment.

[0014] Referring to Figure 1, the hot water heat source unit 1 comprises a sub-boiler 10S and a main boiler 10M housed within a casing 2. The inlet pipe 3 is connected to the sub-boiler 10S, while the outlet pipe 4 is connected to the main boiler 10M.

[0015] The sub-boiler 10S includes a burner 20S, a combustion chamber 30S, a heat exchanger 40S, and a controller 100S. The burner 20S has a nozzle 21S, piping 22S, an electromagnetic pump 23S, a strainer 24S, an electrode rod 25S, an ignition transformer 26S, and a combustion fan 27S. The piping 22S is connected to the nozzle 21S at one end and to a fuel tank (not shown) at the other end. The electromagnetic pump 23S and the strainer 24S are arranged along the path of the piping 22S. By driving the electromagnetic pump 23S, fuel such as kerosene is ejected from the nozzle 21S through the piping 22S after passing through the strainer 24S.

[0016] The tip of the electrode rod 25S is disposed near the nozzle 21S. The electrode rod 25S is connected to the ignition transformer 26S. By driving the ignition transformer 26S, a spark is generated at the tip of the electrode rod 25S. When the combustion fan 27S is driven, air is supplied near the nozzle 21S. Fuel is ejected from the nozzle 21S, and in a state where air is supplied near the nozzle 21S and the above-mentioned spark is generated, the fuel ejected from the nozzle 21S is combusted, and combustion gas is generated in the combustion chamber 30S.

[0017] Inside the heat exchanger 40S, a gas flow path 41S communicating with the combustion chamber 30S is formed. The combustion gas generated in the combustion chamber 30S by the burner 20S flows into the gas flow path 41S from the lower end of the gas flow path 41S, and flows out from the upper end of the gas flow path 41S through the gas flow path 41S. The upper end of the gas flow path 41S is connected to the exhaust pipe 45S, and the exhaust pipe 45S is connected to an exhaust port 5 for exhausting the combustion gas outside the housing 2.

[0018] Inside the heat exchanger 40S, a first water flow path 42S is formed so as to surround the combustion chamber 30S and the gas flow path 41S. The combustion gas by the burner 20S performs heat exchange with the water in the first water flow path 42S while flowing through the gas flow path 41S. Therefore, the water flowing through the heat exchanger 40S (during hot water supply) is heated using the heat generation amount (combustion heat) by the burner 20S while flowing through the first water flow path 42S. Also, even when the hot water supply stops, the water staying in the first water flow path 42S can be heated using the heat generation amount by the burner 20S.

[0019] The main can body 10M is configured in the same way as the sub can body 10S and includes a burner 20M, a combustion chamber 30M, and a heat exchanger 40M. The configurations and operations of the burner 20M, the combustion chamber 30M, and the heat exchanger 40M are the same as those of the burner 20S, the combustion chamber 30S, and the heat exchanger 40S. That is, the burner 20M has a nozzle 21M, a pipe 22M, an electromagnetic pump 23M, a strainer 24M, an electrode rod 25M, an ignition transformer 26M, and a combustion fan 27M, which are the same as the nozzle 21S, the pipe 22S, the electromagnetic pump 23S, the strainer 24S, the electrode rod 25S, the ignition transformer 26S, and the combustion fan 27S.

[0020] Also in the main can body 10M, the fuel ejected from the nozzle 21M is burned, and combustion gas is generated in the combustion chamber 30M. Inside the heat exchanger 40M, a gas flow path 41M communicating with the combustion chamber 30M is formed in the same way as in the heat exchanger 40S. The combustion gas generated in the combustion chamber 30M by the burner 20M flows into the gas flow path 41M, and after passing through the gas flow path 4lM, it is discharged from the exhaust port 5 via the exhaust pipe 45M.

[0021] Inside the heat exchanger 40M, a second water flow path 42M is also formed so as to surround the combustion chamber 30M and the gas flow path 41M. The combustion gas by the burner 20M exchanges heat with the water in the second water flow path 42M while flowing through the gas flow path 41M. Therefore, the water flowing through the heat exchanger 40M (during hot water supply) is heated using the heat generation amount (combustion heat) by the burner 20M while flowing through the second water flow path 42M. Also, even when the hot water supply stops, the water staying in the second water flow path 42M can be heated using the heat generation amount by the burner 2ON.

[0022] The first end (input side) of the first water flow path 42S of the heat exchanger 40S of the sub can body 10S is connected to an inlet pipe 3 for introducing low-temperature water such as tap water. Further, the second end (output side) of the first water flow path 42S is connected to the first end (input side) of the second water flow path 42M of the heat exchanger 40M via a pipe 8. The second end (output side) of the second water flow path 42M is connected to a hot water outlet pipe 4 leading to a water supply tap (not shown) or the like.

[0023] The heat exchanger 40S (sub-boiler 10S) and the heat exchanger 40M (main boiler 10M) are connected in series between the water inlet pipe 3 and the hot water outlet pipe 4 by piping 8. That is, the sub-boiler 10S constitutes the "upstream boiler," while the main boiler 10M constitutes the "downstream boiler," and the piping 8 constitutes the "inter-boiler piping." In addition, in the sub-boiler 10S and the main boiler 10M, the burners 20S and 20M correspond to one embodiment of the "combustion mechanism."

[0024] When the hot water source unit 1 supplies hot water by opening the hot water tap, etc., the same amount of low-temperature water is introduced from the inlet pipe 3 to the heat exchanger 40S, depending on the water pressure of the water supply, etc., as the hot water is heated in the heat exchanger 40M and output from the outlet pipe 4. The low-temperature water introduced from the inlet pipe 3 is heated in the heat exchanger 40S using the heat generated by the burner 20S in the sub-boiler 10S, and then input to the heat exchanger 40M of the main boiler 10M. In the main boiler 10M, the water heated in the heat exchanger 40S is further heated in the heat exchanger 40M using the heat generated by the burner 20M, and then output from the outlet pipe 4. In this way, by connecting the two boilers in series with piping 8, the low-temperature water from the inlet pipe 3 is gradually heated by the sub-boiler 10S and the main boiler 10M, allowing hot water to be supplied via the outlet pipe 4.

[0025] Furthermore, when the hot water tap is closed and the hot water supply is stopped, the water stored inside the sub-boiler 10S and the main boiler 10M can be heated using the heat generated by the burners 20S and 20M, respectively.

[0026] The piping 8 is positioned to connect the upper part of the first water passage 42S of the heat exchanger 40S (above the burner 20S and combustion chamber 30S, corresponding to the position of the gas passage 41S) and the upper part of the second water passage 42M of the heat exchanger 40M (above the burner 20M and combustion chamber 30M, corresponding to the position of the gas passage 41M). Furthermore, the connection point between the piping 8 and the heat exchanger 40S (first water passage 42S) is located at a higher position than the connection point between the piping 8 and the heat exchanger 40M (second water passage 42M).

[0027] Furthermore, the bottom of the first water channel 42S of the heat exchanger 40S and the bottom of the second water channel 42M of the heat exchanger 40M are connected by a pipe 9. By providing the pipe 9, drainage from the heat exchanger 40S (sub-boiler 10S) and the heat exchanger 40M (main boiler 10M) can be efficiently carried out. In addition, by providing the pipe 9 in addition to the pipe 8, it becomes possible to generate water convection between the heat exchanger 40S (sub-boiler 10S) and the heat exchanger 40M (main boiler 10M), and it is expected that the temperature deviation of the water in the heat exchanger 40S (sub-boiler 10S) and the heat exchanger 40M (main boiler 10M), which depend on the height position, will be reduced.

[0028] Furthermore, temperature sensors 110S and 110M for measuring water temperature are arranged in the first water channel 42S of the heat exchanger 40S (sub-boiler 10S) and the second water channel 42M of the heat exchanger 40M (main boiler 10M), respectively. Each of the temperature sensors 110S and 110M can be configured, for example, by a thermistor.

[0029] The temperature sensor 110S is positioned near the connection point between the first water channel 42S of the heat exchanger 40S and the inlet pipe 3. Similarly, the temperature sensor 110M is positioned near the connection point between the second water channel 42M of the heat exchanger 40M and the piping 8.

[0030] The operation of each component constituting the sub-container 10S is controlled by controller 100S. Similarly, the operation of each component constituting the main container 10M is controlled by controller 100M. Controllers 100S and 100M can be configured by microcomputers powered, for example, by connecting the power plug 6 to an AC 100V power supply.

[0031] In the sub-can body 10S, the controller 100S drives the electromagnetic pump 23S and the combustion fan 27S, and generates a spark on the electrode rod 25S using the ignition transformer 26S, thereby starting (turning on) combustion of the burner 20S. After ignition, the controller 100S can maintain the combustion-on state of the burner 20S by maintaining the operation of the electromagnetic pump 23S and the combustion fan 27S. Furthermore, the controller 100S can stop (turn off) combustion of the burner 20S by stopping the electromagnetic pump 23S while the burner 20S is in combustion state. Even after combustion is turned off, the controller 100S can continue to drive the combustion fan 27S for exhaust for a certain period of time.

[0032] Similarly, in the main boiler 10M, the controller 100M can control the on / off switching of the burner 20M by controlling the operation of the electromagnetic pump 23M, the ignition transformer 26M, and the combustion fan 27M.

[0033] Figure 2 is a block diagram illustrating the communication configuration between the remote control and the controllers for each container.

[0034] Referring to Figure 2, the remote control 105 can be positioned on the outer wall side of the housing 2 shown in Figure 1, accompanied by an openable and closable front cover (not shown). The remote control 105 has an input unit 115 for receiving operation instructions from the user. The input unit 115 can consist of operation buttons and / or a touch panel. Operation instructions can include operation / stop commands for the hot water heat source unit 1, timer instruction inputs, and the set temperature Tr for hot water supply. The set temperature Tr corresponds to the control target value of the hot water temperature from the hot water outlet pipe 4.

[0035] Remote control 105 and controller 100M (main tank 10M) are connected via communication line 125. Furthermore, controller 100M (main tank 10M) and controller 100S (sub-tank 10S) are connected via communication line 120. Communication line 125 corresponds to one embodiment of the "first communication means," and communication line 120 corresponds to one embodiment of the "second communication means."

[0036] Therefore, the set temperature Tr input to the remote control 105 can be transmitted not only to the controller 100M but also to the controller 100S. In contrast, as will be explained later in the comparative example, in a configuration where only the communication line 125 is provided and the communication line 120 is not provided, the set temperature Tr input to the remote control 105 can be transmitted to the controller 100M, but the controller 100S cannot know the set temperature Tr.

[0037] <Temperature control of the can body> Next, we will explain the control of water temperature in each boiler (hereinafter simply referred to as "temperature control"). In the hot water heat source unit 1, the target control temperatures Tm* and Ts* are set individually for the main boiler 10M (downstream side) and the sub-boiler 10S (upstream side), and temperature control is also performed individually for each.

[0038] Specifically, in the sub-boiler 10S, temperature control is performed by comparing the temperature T(S) detected by the temperature sensor 110S with the target control temperature Ts*, while in the main boiler 10M, temperature control is performed by comparing the temperature T(M) detected by the temperature sensor 110M with the target control temperature Tm*. Ultimately, by controlling the temperature T(M) detected in the main boiler 10M to the set temperature Tr, hot water supply according to the set temperature Tr is achieved.

[0039] Note that temperature control for the sub-canister 10S and the main canister 10M is performed using a common scheme, except that the target control temperatures Ts* and Tm* differ. Therefore, the following description will focus on the temperature control of canister 10, which encompasses both the sub-canister 10S and the main canister 10M. In the following description, the target control temperatures Ts* and Tm* will be collectively referred to as the target control temperature T*, and the detected temperatures T(S) and T(M) will be collectively referred to as the detected temperature T.

[0040] Figure 3 is a conceptual diagram illustrating temperature control in each of the 10 containers. As shown in Figure 3, the temperature control of the boiler 10 is performed by on / off control of combustion at the rated output Wrt (kcal / h) by the burner 20 (collectively referred to as burners 20S and 20M) based on a comparison of the detected temperature T and the control target temperature T*. In this embodiment, the rated output Wrt is assumed to be common to both the sub-boiler 10S and the main boiler 10M.

[0041] When the burner 20 is in the off state, if the detected temperature T is lower than the control target temperature T*, the burner 20 is controlled to turn on combustion. On the other hand, when the burner 20 is in the on state, if the detected temperature T becomes higher than the control target temperature T*, the burner 20 is controlled to turn off combustion.

[0042] Specifically, in the sub-boiler 10S, temperature control is performed by the controller 100S turning the combustion of the burner 20S on and off according to the transition diagram in Figure 3, based on the temperature T(S) detected by the temperature sensor 110S and the target control temperature Ts*. Similarly, in the main boiler 10M, temperature control is performed by the controller 100M turning the combustion of the burner 20M on and off according to the transition diagram in Figure 3, based on the temperature T(M) detected by the temperature sensor 110M and the target control temperature Tm*.

[0043] The control target temperature Ts* corresponds to one embodiment of the "first control target temperature," and the control target temperature Tm* corresponds to one embodiment of the "second control target temperature." Furthermore, the temperature sensor 110S corresponds to one embodiment of the "first temperature sensor," and the temperature sensor 110M corresponds to one embodiment of the "second temperature sensor."

[0044] As shown in Figure 3, it is also possible to introduce hysteresis between the transition from the combustion-off state to the combustion-on state and the transition from the combustion-on state to the combustion-off state. For example, the transition from the combustion-off state to the combustion-on state can be determined by comparing a temperature α [°C] lower than the control target temperature T* with the detected temperature T, while the transition from the combustion-on state to the combustion-off state can be determined by comparing a temperature β [°C] higher than the control target temperature T* with the detected temperature T.

[0045] Figure 4 is a conceptual diagram for explaining the operation pattern of the can body 10 by the temperature control of FIG. 3. Referring to FIG. 4, the operation pattern of the can body 10 is determined depending on the magnitude relationship between the rated output Wrt in the combustion-on state of the can body 10 and the required output Wrq represented by the following formula (1).

[0046] Wrq = k × (T* - Tin) × Q …(1) In formula (1), Tin [°C] is the input temperature of the can body 10. In the sub-can body 10S, it is the temperature of the low-temperature water introduced from the water inlet pipe 3, while in the main can body 10M, it corresponds to the output temperature (hot water temperature) of the sub-can body 10S. Also, Q [L / min] is the flow rate generated according to the hot water supply from the hot water outlet pipe 4, and k is the unit conversion coefficient.

[0047] When Wrt ≥ Wrq, the detected temperature T can rise to the control target temperature T*. Specifically, by providing the hysteresis described in FIG. 3, the combustion of the burner 20 is intermittently repeated so that the detected temperature T is maintained at the control target temperature T* without causing frequent transitions (so-called hunting) between the combustion-on state and the combustion-off state in a short period of time. Thus, temperature control by intermittent combustion operation is executed.

[0048] The ratio D of the combustion-on period changes according to the surplus amount (Wrt - Wrq) of the rated output Wrt with respect to the required output Wrq, and the larger the surplus amount, the smaller the ratio D.

[0049] When Wrt < Wrq, the combustion-on state is continued (D = 1.0), and continuous combustion operation is executed. However, even by continuous combustion operation, the detected temperature T cannot rise to the control target temperature T*. In this case, the detected temperature T rises to the temperature Tf represented by formula (2) and is then maintained at the temperature Tf lower than the control target temperature T*.

[0050] Tf = Wrt / (k × Q) + Tin …(2) When hot water supply is stopped (Q=0), temperature control is performed to maintain the water stored in each boiler 10 at the target temperature T*. That is, each boiler 10 is kept in the combustion-on state until the detected temperature T reaches the target temperature T*, and then each boiler 10 is turned off. After that, each boiler 10 is turned on again when the detected temperature T decreases due to natural heat dissipation, and performs intermittent combustion operation as shown in Figure 4(a) with a longer on / off cycle compared to when hot water is being supplied.

[0051] Next, using Figure 5, we will explain the settings for the control target temperatures Ts* and Tm* of the upstream sub-boiler 10S and the downstream main boiler 10M.

[0052] Figure 5 shows an example of setting the target temperatures Ts* and Tm* in temperature control. First, as a prerequisite for temperature control, in order to control the main tank 10M to the detected temperature T(M)=Tr for a user-set temperature Tr, it is basically necessary to set Tm*=Tr. In contrast, the target temperature Ts* of the sub-tank 10S differs between the comparative example and this embodiment.

[0053] As shown in Figure 5, in the comparative example, the control target temperature Ts* of the sub-container 10S is fixed to a predetermined temperature Tx (Ts*=Tx). In contrast, the control target temperature Tm* of the main container 10M is set according to the set temperature Tr entered by the user into the remote control 105 (Figure 2) (Tm*=Tr).

[0054] In the comparative example, the user-set temperature Tr needs to be transmitted from the remote control 105 to the controller 100M of the main tank 10M, whereas it is not necessary to transmit the set temperature Tr to the controller 100S of the sub-tank 10S.

[0055] In this embodiment, the controller 100M sets the control target temperature Tm* of the main tank 10M according to the set temperature Tr transmitted via communication with the remote control 105, similar to the comparative example (Tm*=Tr).

[0056] On the other hand, controller 100S can receive the set temperature Tr, which is input by the user to the remote control 105, from controller 100M via the communication line 120. Then, controller 100S can set the control target temperature Ts* of the sub-container 10S using the received set temperature Tr (Ts*=Tr). As a result, the control target temperature Ts* is set to be equivalent to the set temperature Tr, just like the control target temperature Tm* of the main container 10M.

[0057] Next, using Figure 6, we will explain the comparative example shown in Figure 4 and an example of temperature control according to this embodiment.

[0058] In the example shown in Figure 6, the total rated output of the hot water heat source unit 1 is assumed to be Wrttl = 90,000 [kcal / h], and the rated output of each boiler unit 10 (10S and 10M respectively) is assumed to be Wrt = 45,000 [kcal / h].

[0059] Then, assuming operating conditions of low-temperature water temperature Tw=30[°C] from the inlet pipe 3, set temperature Tr=85[°C], and Q=25[L / min], we compare the operation of a comparative example in which Ts*=Tx=50[°C] is set for these operating conditions with the operation of this embodiment in which Ts*=Tr=85[°C] according to the set temperature Tr.

[0060] Under the above operating conditions, the total required output Wrqttl for the hot water heat source unit 1, that is, the sum of the required output for the main tank 10M and the sub-tank 10S, is Wrqttl = (85-30)[℃] × 25[L / min] × 60[min] = 82,500[kcla / h].

[0061] In the comparative example, in the sub-cylinder body 10S, since Ts* = 50 [°C], the required output Wrq to the sub-cylinder body 10S is Wrq = (50 - 30) [°C] × 25 [L / min] × 60 [min] = 30,000 [kcal / h]. At this time, since Wrq < Wrt, the output heat quantity of the sub-cylinder body 10S becomes smaller than the rated output Wrt, and the temperature control (intermittent combustion operation) with T* = 50 [°C] is executed in Fig. 4(a). For this reason, the output temperature of the sub-cylinder body 10S becomes 50 [°C] equivalent to T*.

[0062] On the other hand, the required output Wrq to the main cylinder body 10M in the comparative example is Wrq = (85 - 50) [°C] × 25 [L / min] × 60 [min] = 52,500 [kcal / h], so Wrq > Wrt. Therefore, the output heat quantity of the main cylinder body 10M becomes equivalent to the rated output Wrt, and the temperature control (continuous combustion operation) in Fig. 4(b) is executed. Substituting the above operating conditions (Q = 25 [L / min]), the rated output Wrt = 45,000 [kcal / h], and Tin = 50 [°C] into Equation (2), Tf = 80 [°C] is obtained. That is, the output temperature of the main cylinder body 10M becomes 80 [°C], and the hot water temperature cannot be raised to the set temperature Tr.

[0063] As described above, in the comparative example, due to the low control target temperature Ts*, the output heat quantity of the sub-cylinder body 10S is restricted, and the case where the output heat quantity of the entire hot water heat source machine 1 is insufficient for hot water supply at the set temperature Tr expands.

[0064] Also, in the application of the boiler, for use in snow melting, etc., there are also needs for relatively low-temperature continuous hot water supply (for example, Tr = about 25 [°C] for Tw = about 0 to 5 [°C]). Therefore, it is assumed that the set temperature Tr is required to correspond to a wide range of about 25 [°C] to 85 [°C]. On the other hand, if Ts* = Tx is fixed, hot water supply at a temperature lower than Tx cannot be performed. Therefore, it becomes difficult to set Tx high in order to secure a wide range of the set temperature Tr.

[0065] Therefore, in the comparative example, since the control target temperature Ts* in the sub-cylinder body 10S is set to a fixed value, there is a concern that it may be a demerit that the hot water supply capacity corresponding to the set temperature Tr is limited.

[0066] On the other hand, in the present embodiment, in the sub-cylinder body 10S, since Ts* = Tr = 85 [°C], the required output Wrq to the sub-cylinder body 10S is the same as the total required output Wrqttl, which is 82,500 [kcla / h], and Wrq > Wrt. Therefore, the output of the sub-cylinder body 10S becomes equal to the rated output Wrt, and the temperature control (continuous combustion operation) in Fig. 4(b) is executed. Substituting the above operating conditions (Q = 25 [L / min]), rated output Wrt = 45,000 [kcal / h], and Tin = 30 [°C] into Equation (2), Tf = 60 [°C].

[0067] On the other hand, the required output Wrq to the main cylinder body 10M in the present embodiment is Wrq = (85 - 60) [°C] × 25 [L / min] × 60 [min] = 37,500 [kcla / h], so Wrq < Wrt. Therefore, the output of the main cylinder body 10M becomes smaller than the rated output Wrt, and the temperature control (intermittent combustion operation) with T* = 85 [°C] shown in Fig. 4(a) is executed. For this reason, the output temperature of the main cylinder body 10M can be made equal to the set temperature Tr, which is 85 [°C].

[0068] As described above, it is understood that in the present embodiment, it is possible to cope with the above usage conditions where hot water supply cannot be performed at the set temperature Tr in the comparative example. Further, even if the set temperature Tr is set relatively low, since Ts* = Tm* = Tr, by controlling the output temperature of the sub-cylinder body 10S to be equal to the set temperature Tr and maintaining the main cylinder body 10M in the combustion-off state, hot water supply at the set temperature Tr can be realized.

[0069] As described above, according to the hot water heat source machine according to the present embodiment, by the temperature control of setting the control target temperature Ts* in the sub-cylinder body 10S to be equal to the set temperature Tr, that is, the control target temperature Tm* in the main cylinder body 10M, the hot water supply capacity corresponding to the set temperature Tr can be improved.

[0070] <Variable control of the control target temperature for operation equalization> In the above-described embodiment, since the control target temperature Ts* in the sub-cylinder body 10S is set to be equal to the set temperature Tr, the main cylinder body 10M operates so as to compensate for the heat quantity shortage of the rated output Wrt of the sub-cylinder body 10S with respect to the total required output Wrqttl to the hot water heat source machine 1.

[0071] Therefore, according to the magnitude relationship among the total required output Wrqttl, the rated output Wrt of the sub-cylinder body 10S, and the total rated output Wrttl (= 2·Wrt) of the hot water heat source machine 1, the operations of the sub-cylinder body 10S and the main cylinder body 10M are as follows.

[0072] In the case of Wrqttl < Wrt (hereinafter referred to as case A), the sub-cylinder body 10S operates in an intermittent combustion operation as shown in FIG. 4(a), so that the output temperature of the sub-cylinder body 10S can be raised to the set temperature Tr. Since there is no need to raise the temperature of the main cylinder body 10M, the combustion-off state is continued (combustion stop operation), but by controlling the temperature in the sub-cylinder body 10S, the hot water outlet temperature (hot water supply temperature) from the main cylinder body 10M can be controlled to the set temperature Tr.

[0073] In the case of Wrt ≦ Wrqttl < Wrttl (= 2·Wrt) (hereinafter referred to as case B), the sub-cylinder body 10S operates in a continuous combustion operation in which the combustion-on state is continued as shown in FIG. 4(b), but the output temperature of the sub-cylinder body 10S does not rise to the set temperature Tr. Further, by the main cylinder body 10M operating in an intermittent combustion operation as shown in FIG. 4(a), the temperature shortage with respect to the set temperature Tr can be raised. Thereby, the hot water outlet temperature (hot water supply temperature) from the main cylinder body 10M is controlled to the set temperature Tr. The usage conditions illustrated in FIG. 6 are included in this case B.

[0074] In the case where Wrqttl ≥ Wrttl (= 2·Wrt), both the sub-boiler 10S and the main boiler 10M will operate in continuous combustion mode as shown in Figure 4(b). The hot water temperature (supply temperature) from the main boiler 10M will be equal to the set temperature Tr (when Wrqttl = Wrttl) or lower than the set temperature Tr (when Wrqttl > Wrttl).

[0075] Therefore, if the control target temperature Ts*=Tr of the sub-canister 10S is maintained, in the above-mentioned cases A and B, the operating rate (number of combustion cycles and combustion time) of the sub-canister 10S will be excessive compared to the main canister 10M, raising concerns that the failure frequency of the sub-canister 10S will increase.

[0076] Therefore, in this embodiment, based on temperature control where the control target temperature Ts* = Tr of the sub-boiler 10S (lower part of Figure 5), the operating rate of the sub-boiler 10S and the main boiler 10M can be balanced by further combining this with variable control of the control target temperature shown in Figure 7.

[0077] Figure 7 is a flowchart illustrating the control of changing the target temperature of each tank. Each step shown in Figure 7 (hereinafter simply referred to as "S") can be executed by controller 100S or controller 100M.

[0078] In S110, the set temperature Tr entered by the user in the remote control 105 is transmitted to controllers 100M and 100S. Controller 100M sets the control target temperature Tm*=Tr for the main tank 10M, and controller 100S sets the control target temperature Ts*=Tr for the sub-tank 10S.

[0079] In the sub-container 10S and the main container 10M, the operation of the burners 20S and 20M is individually controlled by controllers 100S and 100M, respectively, according to the temperature control shown in Figure 3.

[0080] In S120, controllers 100S and 100M collect drive information for burners 20S and 20S based on the temperature control described above, respectively. The drive information may include at least one of the combustion time of burners 20S and 20M, and the number of combustion cycles (number of transitions from the combustion-off state to the combustion-on state).

[0081] Controllers 100S and 100M determine in S130 whether a certain update cycle (for example, several minutes) has elapsed. When the update cycle has elapsed (when S130 determines YES), S140 updates the drive parameters PDs of the sub-boiler 10S (burner 20S) and the drive parameters PDm of the main boiler 10M (burner 20M) to the latest values ​​using the drive information collected in S120 since the last update. Note that the drive parameters PDs are one example of a parameter that quantifies the first operating degree of the upstream boiler, and the drive parameters PDm are one example of a parameter that quantifies the second operating degree of the downstream boiler.

[0082] The drive parameters PDs and PDm, respectively, quantify the operating rate of the sub-canister 10S (burner 20S) and main canister 10M (burner 20M) based on the combustion time and / or number of combustion cycles, according to a common calculation formula. A larger value is calculated for longer combustion times or a higher number of combustion cycles. In principle, the processing from S110 to S140 can be executed individually on controllers 100S and 100M, respectively.

[0083] In S150, the drive parameters PDs and PDm after updating in S140 are compared. Specifically, as described above, under the initial conditions where PDs ≥ PDm, it is determined whether (PDs - PDm) is greater than the judgment value Pt1. The judgment value Pt1 is predetermined as the threshold for the bias in the operating rate of the sub-boiler 10S (burner 20S) relative to the main boiler 10M (burner 20M).

[0084] When PDs-PDm > Pt1 (YES judgment in S150), S170 lowers the control target temperature Ts* of the sub-container 10S from its current value. For example, Ts* can be lowered by ΔTs* from the current set value according to a preset step size (increase amount) ΔTs*.

[0085] When the control target temperature Ts* decreases, the output of the sub-boiler 10S decreases in cases A and B described above, and the output of the main boiler 10M increases in proportion to this decrease. This increases the operating rate of the main boiler 10M, thereby suppressing the imbalance in operating rate to the sub-boiler 10S.

[0086] When PDs-PDm≦Pt1 (NO determination in S150), S160 determines, conversely to S150, whether (PDm-PDs) is greater than or equal to determination value Pt2. Determination value Pt2 is predetermined as a threshold for the bias in the operating rate of the main tank 10M (burner 20M) relative to the sub-tank 10S (burner 20S). Determination values ​​Pt1 and Pt2 may be set to the same value or to different values.

[0087] As the control target temperature Ts* is repeatedly lowered by S170, the operating rate of the main boiler 10M increases, which may cause PDm to become larger than PDs, contrary to the initial value. The judgment in S160 allows detection that lowering the control target temperature Ts* too much has caused an imbalance in the operating rate of the main boiler 10M (burner 20M) relative to the sub-boiler 10S (burner 20S).

[0088] When PDm - PDs > Pt2 (YES judgment in S160), the control target temperature Ts* of the sub-container 10S is increased from its current value by S172. For example, Ts* can be increased by ΔTs* from the current set value.

[0089] As the control target temperature Ts* rises, the output of the sub-boiler 10S increases compared to the current level. Consequently, the output of the main boiler 10M decreases in proportion to this increase. This reduces the operating rate of the main boiler 10M, thereby suppressing an imbalance in operating rate to the main boiler 10M.

[0090] On the other hand, when PDs-PDm≦Pt1 and PDm-PDs≦Pt2 (when NO is determined in S160), the bias in operating degree between the sub-boiler 10S and the main boiler 10M is less than or equal to the determination values ​​Pt1 and Pt2, so the control target temperature Ts* is maintained at its current value by S175.

[0091] The processing in steps S150 to S175 can be performed by the controller 100S, for example, by receiving the drive parameter PDm of the main tank 10M from the controller 100M. In this case, the controller 100S can directly change the target temperature Ts*.

[0092] Alternatively, the controller 100M can perform the processing in steps S150 to S175 by receiving the drive parameters PDs of the sub-container 10S from the controller 100S. In this case, in steps S170 and S172, a command to decrease or increase the target temperature Ts* is output from the controller 100M to the controller 100S, and the controller 100S can change the target temperature Ts* according to the command from the controller 100M.

[0093] In S180, a determination is made as to whether or not the hot water supply is stopped (water shutoff determination). In this embodiment, the output of each boiler 10 in the combustion-on state is fixed to the rated value (Wrt), and the detection value of the flow rate Q is not required for temperature control. Therefore, S170 can detect a water shutoff and make a YES determination when the combustion-off period in the sub-boiler 10S and the main boiler 10M continues beyond a predetermined determination time.

[0094] The judgment time in this case can be predetermined to be long enough to clearly distinguish the combustion off period during intermittent combustion operation (Figure 4(b)) when hot water is being supplied (Q>0).

[0095] When S180 determines NO, i.e., when no water stoppage is detected, the processes from S120 to S175 are repeated to suppress any imbalance in the operating rates between the sub-boiler 10S and the main boiler 10M during hot water supply.

[0096] On the other hand, when the YES determination is made in S180, that is, when a water stoppage is detected, the process is terminated and the process from S110 is resumed. As a result, the control target temperatures Ts* and Tm* are initialized to the default values ​​in this embodiment, which are the set temperatures Tr* (Ts*=Tr, Tm*=Tr).

[0097] In this way, by combining the control of changing the target temperature of each boiler shown in Figure 7, the target temperature Ts* of the sub-boiler 10S is set according to the set temperature Tr. This not only improves the hot water supply capacity corresponding to the set temperature Tr, but also makes it possible to further suppress the bias in operating rates between the sub-boiler 10S and the main boiler 10M.

[0098] In the example configuration shown in Figure 1, burners 20S and 20M using oil (kerosene) as fuel are shown as one embodiment of the "combustion mechanism." However, a "combustion mechanism" can be constructed with any fuel and configuration, as long as the heat of combustion can be used to raise the temperature of the heat exchangers 40S and 40M.

[0099] Furthermore, in this embodiment, as explained in Figure 2, information can be shared via communication between the controller 100M (main tank 10M) and 100S (sub-tank 10S). Therefore, by sharing information related to the equipment failure status between the main tank 10M and the sub-tank 10S, it is possible to perform a determination of whether or not operation can continue in the event of a failure.

[0100] For example, if a malfunction occurs in one of the burners 20M and 20S that prevents it from entering a combustion-on state, the feasibility of hot water operation can be determined based on whether or not the combustion fan 27S or 27M is malfunctioning.

[0101] Specifically, if both combustion fans 27S and 27M can be driven normally (no malfunctions), it can be determined that hot water supply operation can continue with a limited hot water supply capacity by driving both combustion fans 27S and 27M and burning fuel in the other burner that is not malfunctioning. On the other hand, if the combustion fan of the malfunctioning burner cannot be driven, there is a risk that the entire amount of combustion gas will not be able to be exhausted from the exhaust port 5, so it can be determined that hot water supply cannot be continued by stopping fuel combustion in both burners 20S and 20M.

[0102] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present invention is indicated by the claims rather than by the foregoing description, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0103] 1 Hot water heat source unit, 2 Housing, 3 Inlet pipe, 4 Outlet pipe, 5 Exhaust port, 6 Power plug, 8,9 Piping (between tanks), 10M Main tank, 10S Sub-tank, 20M,20S Burner, 21M,21S Nozzle, 23M,23S Electromagnetic pump, 24M,24S Strainer, 25M,25S Electrode rod, 26M,26S Ignition transformer, 27M,27S Combustion fan, 40M,40S Heat exchanger, 41M,41S Gas flow path, 42M Second water flow path (main tank), 42S First water flow path (sub-tank), 45M,45S Exhaust pipe, 100M,100S Controller, 105 Remote control, 110M,110S Temperature sensor, 115 Input section, 120,125 Communication line, PDm, PDs drive parameters, Pt1, Pt2 judgment value, T, T(S), T(M) detected temperature, T*, Tm*, Ts* control target temperature, Tr set temperature, Wrq requested output (boiler), Wrqttl total requested output (hot water heat source unit), Wrt rated output (each boiler), Wrttl total rated output (hot water heat source unit).

Claims

1. An upstream boiler body having a first water channel connected to an inlet pipe, A downstream boiler body having a second water channel connected to the hot water outlet pipe, Between the inlet pipe and the outlet pipe, there is inter-boiler piping connecting the first water channel and the second water channel in order to connect the upstream boiler and the downstream boiler in series, Each of the upstream and downstream sections of the boiler is: A combustion mechanism that generates heat from fuel combustion, A heat exchanger that heats the fluid in the first water channel or the second water channel using the heat generated by the combustion mechanism, The combustion mechanism includes a controller that controls the on / off switching of combustion to generate a predetermined amount of heat, The controller of the upstream boiler controls the on / off of combustion by the combustion mechanism of the upstream boiler based on a comparison between the temperature detected by the first temperature sensor provided in the first water flow path and the first control target temperature. The controller of the downstream boiler controls the on / off of combustion of the combustion mechanism of the downstream boiler based on a comparison between the temperature detected by the second temperature sensor provided in the second water flow path and the second control target temperature. A hot water heat source unit in which the first control target temperature and the second control target temperature are set to be equivalent to the set temperature of the hot water supplied from the hot water outlet pipe.

2. The hot water heat source machine according to claim 1, wherein the first control target temperature is initially set to an initial value equivalent to the set temperature, and then changed over time to balance the first operating degree of the combustion mechanism of the upstream boiler and the second operating degree of the combustion mechanism of the downstream boiler.

3. The first control target temperature is modified so that it decreases from its current value when the first operating rate is higher than the second operating rate, and increases from its current value when the second operating rate is higher than the first operating rate. The hot water heat source machine according to claim 2, wherein if the combustion off state of both the combustion mechanism of the downstream boiler and the combustion mechanism of the upstream boiler continues for more than a predetermined determination time, the first control target temperature is returned to the initial value.

4. The inter-boiler piping is configured to connect the portion of the downstream boiler above the combustion mechanism of the second water channel and the portion of the upstream boiler above the combustion mechanism of the first water channel. The first temperature sensor is provided near the connection point with the pre-described water pipe in the first water flow path, The hot water heat source machine according to any one of claims 1 to 3, wherein the second temperature sensor is provided near the connection point of the second water flow path with the inter-boiler piping.

5. The hot water heat source machine according to any one of claims 1 to 3, wherein the upstream boiler, the downstream boiler, and the inter-boiler piping are housed in a single enclosure.

6. A remote control having an input section for the set temperature, A first communication means between the remote control and the controller of the downstream container, The system further comprises a second communication means between the controllers of the upstream and downstream boilers, The second control target temperature is set by the controller of the downstream container using the set temperature transmitted from the remote control by the first communication means. The hot water heat source machine according to any one of claims 1 to 3, wherein the first control target temperature is set by the controller of the upstream boiler using the set temperature transmitted from the controller of the downstream boiler by the second communication means.

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