Combustion heat source machine

Abstract

To provide a technique capable of suppressing overheating of components in a housing.SOLUTION: This combustion heat source machine includes a housing, a burner stored in the housing, a combustion fan for supplying air for combustion to the burner, a heat exchanger heated by combustion of the burner, a temperature sensor for detecting a temperature of fluid flowing in the heat exchanger or flowing out of the heat exchanger, and a controller. The controller is configured to drive the combustion fan when causing the burner to perform combustion. The number of revolutions of the combustion fan while the burner is performing combustion corresponds to the amount of heating by the burner. The controller is configured to increase the thermal dose of the burner such that the thermal dose of the burner falls within a second thermal dose range higher than the first thermal dose range when the thermal dose of the burner is within the first thermal dose range and the temperature detected by the temperature sensor exceeds a first reference temperature corresponding to the first thermal dose range.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a combustion heat source machine. [Background technology]

[0002] Patent Document 1 discloses a combustion heat source machine. The combustion heat source machine includes a housing, a burner accommodated in the housing, a combustion fan that supplies combustion air to the burner, a heat exchanger that is heated by combustion in the burner, a temperature sensor that detects the temperature of fluid flowing into the heat exchanger, and a controller. The controller is configured to drive the combustion fan when the burner is combusted. The controller is configured to prevent the burner from combusting when the temperature detected by the temperature sensor exceeds an upper limit temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-204897 Summary of the Invention [Problem to be solved by the invention]

[0004] In some combustion heat source devices, the rotation speed of the combustion fan when the burner is burning corresponds to the amount of heat generated by the burner. Furthermore, when the burner is burning in a combustion heat source device, the components inside the housing are cooled by the airflow generated by the operation of the combustion fan. Therefore, when the amount of heat generated by the burner is large, the airflow generated by the operation of the combustion fan is also strong, and the components inside the housing are sufficiently cooled. However, when the amount of heat generated by the burner is small, the airflow generated by the operation of the combustion fan is also weak, and the components inside the housing are not sufficiently cooled, and there is a risk of them overheating. This specification provides technology that can prevent the components inside the housing from overheating. [Means for solving the problem]

[0005] In a first aspect of the present technology, a combustion heat source device may include a housing, a burner accommodated in the housing, a combustion fan that supplies combustion air to the burner, a heat exchanger that is heated by combustion of the burner, a temperature sensor that detects the temperature of a fluid flowing into or out of the heat exchanger, and a controller. The controller may be configured to drive the combustion fan when the burner is combusted. The rotation speed of the combustion fan when the burner is combusting may correspond to a heat amount of the burner. The controller may be configured to increase the heat amount of the burner when the heat amount of the burner is within a first heat amount range and the temperature detected by the temperature sensor exceeds a first reference temperature corresponding to the first heat amount range, so that the heat amount of the burner falls into a second heat amount range that is higher than the first heat amount range.

[0006] In a combustion heat source device, when the temperature of the fluid flowing into the heat exchanger is high, the amount of heat required by the burner is small. Therefore, when the amount of heat generated by the burner is small and the temperature of the fluid flowing into the heat exchanger is high, the amount of heat generated by the burner is maintained at a low level, which can result in insufficient cooling by the airflow generated by driving the combustion fan and the components inside the housing being overheated. With the above configuration, when the amount of heat generated by the burner is small and the temperature of the fluid flowing into the heat exchanger (or the temperature of the fluid flowing out of the heat exchanger) is high, the controller increases the amount of heat generated by the burner, which in turn strengthens the airflow generated by driving the combustion fan, allowing for sufficient cooling by the airflow generated by driving the combustion fan and preventing the components inside the housing from being overheated.

[0007] In a second aspect of the present technology, in the first aspect described above, the controller may be configured to extinguish the burner when an extinguishing condition is satisfied that the temperature detected by the temperature sensor exceeds an upper limit temperature that is higher than the first reference temperature, and to continue driving the combustion fan even after the extinguishing condition is satisfied and the burner is extinguished.

[0008] According to the above configuration, even after the extinguishing conditions are met and the burner is extinguished, cooling by the air flow generated by driving the combustion fan continues, thereby preventing the components inside the housing from overheating.

[0009] In a third aspect of the present technology, in the second aspect, the controller may be configured to re-ignite the burner when a predetermined time has elapsed after the extinguishing condition is satisfied and the burner is extinguished.

[0010] According to the above configuration, after the extinguishing conditions are met and the burner is extinguished, the burner is not reignited until a predetermined time has elapsed, so that the airflow generated by driving the combustion fan can sufficiently cool the components inside the housing.

[0011] In a fourth aspect of the present technology, in the third aspect, the controller may be configured not to re-ignite the burner even after the extinguishing condition is satisfied and the burner is extinguished, if a re-ignition condition is not satisfied, that is, the temperature detected by the temperature sensor falls below a lower limit temperature that is lower than the first reference temperature, even if the predetermined time has elapsed after the extinguishing condition is satisfied.

[0012] If the burner is reignited when the temperature of the fluid flowing into the heat exchanger is high, the amount of heat generated by the burner will be small and the temperature of the fluid flowing into the heat exchanger will likely remain high, potentially maintaining this low amount of heat generated by the burner. In this case, the airflow generated by the combustion fan's operation will not provide sufficient cooling, potentially causing components in the housing to overheat. With the above configuration, the burner is not reignited until the temperature of the fluid flowing into the heat exchanger (or the temperature of the fluid flowing out of the heat exchanger) has sufficiently dropped, preventing a situation in which the amount of heat generated by the burner is small and the temperature of the fluid flowing into the heat exchanger is high after the burner is reignited, thereby preventing components in the housing from overheating.

[0013] In a fifth aspect of the present technology, in any one of the second to fourth aspects, the device may further include a circulation pump that sends the fluid to the heat exchanger. The controller may be configured to drive the circulation pump when the burner is combusted, and to continue driving the circulation pump even after the extinguishing condition is satisfied and the burner is extinguished.

[0014] For example, in a heating system in which fluid is circulated between a combustion heat source and a heating terminal, if the circulation pump continues to operate with the burner extinguished, the temperature of the fluid flowing into the heat exchanger will decrease. With the above configuration, the temperature of the fluid flowing into the heat exchanger can be sufficiently decreased after the burner is extinguished when the extinguishing condition is met, and before the burner is reignited. This prevents the burner from generating a small amount of heat and the fluid flowing into the heat exchanger from becoming too hot after the burner is reignited, thereby preventing overheating of components inside the housing.

[0015] In a sixth aspect of the present technology, in any one of the first to fifth aspects, the controller may be configured to increase the heating amount of the burner so that the heating amount of the burner falls within a third heating amount range higher than the second heating amount range when the heating amount of the burner is within the second heating amount range and the temperature detected by the temperature sensor exceeds a second reference temperature corresponding to the second heating amount range and higher than the first reference temperature.

[0016] For example, if the increase in the heat output of the burner is small, it may happen that cooling by the airflow generated by driving the combustion fan remains insufficient even though the heat output of the burner is increased. With the above configuration, in such a case, the controller further increases the heat output of the burner, thereby enabling sufficient cooling by the airflow generated by driving the combustion fan and preventing overheating of the components inside the housing. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram schematically showing a state in which a combustion heat source unit 2 according to an embodiment performs a heating operation. [Figure 2] FIG. 2 is a diagram schematically showing a state in which a combustion heat source unit 2 according to an embodiment performs a hot water supply operation. [Figure 3] 10 shows a part of a flowchart of a burner heat amount increasing process executed by a controller 86 in a combustion heat source machine 2 according to the embodiment. [Figure 4] 10 shows the remaining part of the flowchart of the burner heat amount increasing process executed by the controller 86 in the combustion heat source machine 2 according to the embodiment. [Figure 5] 10 is a graph for explaining a situation in which the burner heating amount is increased in the combustion heat source device 2 according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] (Example) The combustion heat source device 2 shown in FIG. 1 includes a housing 4, a combustion chamber 6, a burner 8, an exhaust duct 10, a primary heat exchanger 12, a secondary heat exchanger 14, a burner forward path 16, a burner return path 18, and a circulation pump 20. An air intake pipe 22 through which air flows in from outside the housing 4 and an exhaust pipe 24 through which exhaust gas flows out to the outside of the housing 4 are connected to the top of the housing 4. The combustion chamber 6 is disposed inside the housing 4. The burner 8 is disposed at the top inside the combustion chamber 6 so as to generate a downward combustion flame. The primary heat exchanger 12 is disposed inside the combustion chamber 6 below the burner 8. The secondary heat exchanger 14 is disposed inside the combustion chamber 6 below the primary heat exchanger 12. The exhaust duct 10 connects the bottom of the combustion chamber 6 to the exhaust pipe 24.

[0019] A heating forward pipe 26 and a heating return pipe 28, through which a heating heat medium (water or antifreeze) flows, are connected to the bottom of the housing 4. The combustion heat source unit 2 sends out high-temperature heat medium to a heating terminal (not shown) via the heating forward pipe 26. The combustion heat source unit 2 also receives, from the heating terminal, the heat medium that has been cooled by heat dissipation at the heating terminal, via the heating return pipe 28. The upstream end of the burner forward path 16 is connected to the heating return pipe 28. The downstream end of the burner forward path 16 is connected to the upstream end of the secondary heat exchanger 14. The downstream end of the secondary heat exchanger 14 is connected to the upstream end of the primary heat exchanger 12. The downstream end of the primary heat exchanger 12 is connected to the upstream end of the burner return path 18. The downstream end of the burner return path 18 is connected to the heating forward pipe 26. A circulation pump 20 is provided in the burner forward path 16. The circulation pump 20 causes the heat medium in the burner outward path 16 to flow toward the secondary heat exchanger 14. A heating return thermistor 30 that detects the temperature of the heat medium flowing into the secondary heat exchanger 14 is provided near the downstream end of the burner outward path 16. A heating outward thermistor 32 that detects the temperature of the heat medium flowing out from the primary heat exchanger 12 is provided near the upstream end of the burner return path 18.

[0020] The combustion heat source unit 2 further includes a fuel gas flow path 34, a zero governor 36, a flow rate control valve 38, a mixer 40, and a combustion fan 42. A fuel gas supply pipe 44 is connected to the bottom of the housing 4. Fuel gas, such as city gas, is supplied to the combustion heat source unit 2 via the fuel gas supply pipe 44. The upstream end of the fuel gas flow path 34 is connected to the fuel gas supply pipe 44. The downstream end of the fuel gas flow path 34 is connected to the mixer 40. The zero governor 36 is provided in the fuel gas flow path 34 and adjusts the pressure of the fuel gas to atmospheric pressure. The flow rate control valve 38 is provided in the fuel gas flow path 34 downstream of the zero governor 36. The flow rate control valve 38 adjusts the opening of the fuel gas flow path 34 to adjust the flow rate of the fuel gas flowing through the fuel gas flow path 34. The mixer 40 is connected to the combustion fan 42. The mixer 40 draws air into the housing 4 when the combustion fan 42 is driven. Furthermore, the mixer 40 uses the negative pressure of the air flowing inside the mixer 40 to suck in fuel gas from the fuel gas flow path 34 and mix the air and fuel gas. When the combustion fan 42 is driven, the mixed gas of air and fuel gas is supplied from the mixer 40 to the burner 8 via the combustion fan 42. The mixture ratio of air to fuel gas in the mixed gas is adjusted to an appropriate mixture ratio according to the type of fuel gas by the flow rate control valve 38 adjusting the opening of the fuel gas flow path 34.

[0021] An ignition plug 46 and a flame rod 48 are provided near the burner 8 inside the combustion chamber 6. The ignition plug 46 is electrically connected to an igniter 50 arranged outside the combustion chamber 6. When the combustion fan 42 is driven and mixed gas is supplied to the burner 8, the ignition plug 46 is discharged by the igniter 50, causing the burner 8 to start combustion. The flame rod 48 can detect whether or not the burner 8 is burning.

[0022] The combustion heat source unit 2 further includes a liquid-liquid heat exchanger 52, an internal circulation path 54, a three-way valve 56, a heat exchanger outward path 58, a heat exchanger return path 60, a heat exchanger bypass path 62, a water volume servo valve 64, and a bypass servo valve 66. The liquid-liquid heat exchanger 52 includes a heat medium path 52a and a water path 52b, and exchanges heat between the heat medium flowing through the heat medium path 52a and the water flowing through the water path 52b. The heat medium path 52a is provided in the internal circulation path 54. The upstream end of the internal circulation path 54 is connected to the burner return path 18. The downstream end of the internal circulation path 54 is connected to the burner outward path 16, which is upstream of the circulation pump 20. The three-way valve 56 is provided at the connection between the internal circulation path 54 and the burner outward path 16. The three-way valve 56 can be switched between a state in which the heating return pipe 28 side is fully open and the internal circulation path 54 side is fully closed (see FIG. 1), and a state in which the internal circulation path 54 side is fully open and the heating return pipe 28 side is fully closed (see FIG. 2). The three-way valve 56 can also be set to a state in which both the heating return pipe 28 side and the internal circulation path 54 side are half open.

[0023] A water supply pipe 68 and a hot water supply pipe 70, through which hot water flows, are connected to the bottom of the housing 4. The combustion heat source unit 2 heats the water flowing in from the water supply pipe 68 and sends high-temperature water to the hot water supply pipe 70. The upstream end of the heat exchanger outgoing path 58 is connected to the water supply pipe 68. The downstream end of the heat exchanger outgoing path 58 is connected to the inlet of the water flow path 52b. The upstream end of the heat exchanger return path 60 is connected to the outlet of the water flow path 52b. The downstream end of the heat exchanger return path 60 is connected to the hot water supply pipe 70. The upstream end of the heat exchanger bypass path 62 is connected to the heat exchanger outgoing path 58. The downstream end of the heat exchanger bypass path 62 is connected to the heat exchanger return path 60. A water volume servo valve 64 is provided in the heat exchanger outgoing path 58 upstream of the connection point of the heat exchanger bypass path 62. The water volume servo valve 64 adjusts the opening of the heat exchanger outbound path 58 to adjust the flow rate of water flowing through the heat exchanger outbound path 58. A feedwater flow rate sensor 72 and a feedwater thermistor 74 are provided in the heat exchanger outbound path 58. The feedwater flow rate sensor 72 detects the flow rate of water flowing in from the feedwater pipe 68. The feedwater thermistor 74 detects the temperature of the water flowing in from the feedwater pipe 68. The bypass servo valve 66 is provided at the connection point between the heat exchanger bypass path 62 and the heat exchanger return path 60. The bypass servo valve 66 can adjust the ratio of the flow rate of water flowing from the water flow path 52b of the liquid-liquid heat exchanger 52 into the heat exchanger return path 60 to the flow rate of water flowing from the heat exchanger bypass path 62 into the heat exchanger return path 60. A heat exchanger outlet thermistor 76 is provided in the heat exchanger return path 60 upstream of the bypass servo valve 66 to detect the temperature of water flowing out from the water flow path 52b of the liquid-liquid heat exchanger 52. A hot water supply thermistor 78 for detecting the temperature of water flowing out to the hot water supply pipe 70 is provided in the heat exchanger return line 60 downstream of the bypass servo valve 66 .

[0024] The combustion heat source unit 2 further includes a drain pan 80 and a drain passage 82. A drain pipe 84 is connected to the bottom of the housing 4. Drain adhering to the outer surface of the secondary heat exchanger 14 drips into the drain pan 80. The upstream end of the drain passage 82 is connected to the drain pan 80. The downstream end of the drain passage 82 is connected to the drain pipe 84. The drain that drips into the drain pan 80 is discharged into the drain pipe 84 via the drain passage 82.

[0025] The combustion heat source unit 2 further includes a controller 86. The controller 86 includes a CPU, ROM, RAM, etc. Various operating programs are stored in the ROM. Various signals input to the controller 86 and various data generated in the process of the CPU executing processing are temporarily stored in the RAM. The controller 86 controls the operation of each component of the combustion heat source unit 2 by the CPU executing processing based on the information stored in the ROM and RAM.

[0026] 1, when performing heating operation, the controller 86 switches the three-way valve 56 to a state where the heating return pipe 28 side is fully open and the internal circulation path 54 side is fully closed, and also drives the circulation pump 20. The controller 86 also drives the combustion fan 42 to supply a mixture of fuel gas and air to the burner 8, and drives the igniter 50 to start combustion in the burner 8. As a result, the heat medium that has flowed from the heating return pipe 28 into the burner outward path 16 passes through the secondary heat exchanger 14 and the primary heat exchanger 12 in this order, where it is heated, and then flows out from the burner return path 18 into the heating outward pipe 26.

[0027] 2, when hot water supply operation is performed, the controller 86 switches the three-way valve 56 to a state in which the heating return pipe 28 side is fully closed and the internal circulation path 54 side is fully open, and also drives the circulation pump 20. The controller 86 also drives the combustion fan 42 to supply a mixture of fuel gas and air to the burner 8, and drives the igniter 50 to start combustion in the burner 8. As a result, the heat medium in the burner outward path 16 passes through the secondary heat exchanger 14 and the primary heat exchanger 12 in this order and is heated, and then passes through the burner return path 18 and the heat medium flow path 52a of the liquid-liquid heat exchanger 52 to dissipate heat and return to the burner outward path 16. In addition, water flowing from the water supply pipe 68 into the heat exchanger outward path 58 branches into the water flow path 52b of the liquid-liquid heat exchanger 52 and the heat exchanger bypass path 62, and the water heated by passing through the water flow path 52b and the water that has passed through the heat exchanger bypass path 62 merge together, and then flows out from the heat exchanger return path 60 into the hot water supply pipe 70.

[0028] The combustion heat source unit 2 can also perform heating operation and hot water supply operation simultaneously. In this case, the controller 86 switches the three-way valve 56 to a state where the heating return pipe 28 side and the internal circulation path 54 side are both half open, and drives the circulation pump 20. The controller 86 also drives the combustion fan 42 to supply a mixture of fuel gas and air to the burner 8, and drives the igniter 50 to start combustion in the burner 8.

[0029] (Burner heat amount increase processing) In heating operation, the temperature of the heat medium to be sent to the heating supply pipe 26 is specified in advance based on the heating set temperature. On the other hand, in heating operation, when the outside air temperature is high or when not much heat is dissipated at the heating terminal, a relatively high-temperature heat medium may return to the heating return pipe 28. In this case, in the combustion heat source unit 2, the temperature rise of the heat medium when passing through the secondary heat exchanger 14 and the primary heat exchanger 12 must be reduced, so control is performed to reduce the flow rate of the fuel gas supplied to the burner 8 and reduce the amount of heat generated by the burner 8.

[0030] In the combustion heat source unit 2 of this embodiment, when the flow rate of fuel gas supplied to the burner 8 is reduced, the rotation speed of the combustion fan 42 is correspondingly reduced. Even if the combustion chamber 6 becomes hot due to combustion by the burner 8, the components inside the housing 4 are cooled by the airflow generated by the operation of the combustion fan 42. Therefore, when the amount of heat generated by the burner 8 is large, the airflow generated by the operation of the combustion fan 42 is also strong, and the components inside the housing 4 are sufficiently cooled. However, when the amount of heat generated by the burner 8 is small, the airflow generated by the operation of the combustion fan 42 is weak, and there is a risk that the components inside the housing 4 will not be sufficiently cooled. Therefore, in this embodiment, the controller 86 performs the burner heat amount increase process shown in FIGS. 3 and 4 to increase the amount of heat generated by the burner 8 (and therefore increase the rotation speed of the combustion fan 42) when the temperature of the heat medium returning to the heating return pipe 28 is high and the amount of heat generated by the burner 8 is small (and therefore the rotation speed of the combustion fan 42 is small).

[0031] When the controller 86 starts the burner heating amount increase process of Figures 3 and 4, the timer count value (see S16, S18, S22, S28, etc.) is reset, and the heating amount increase flag (see S20, S24, S42, etc.) is turned off.

[0032] 3, in S2, controller 86 determines whether the temperature detected by heating return thermistor 30 (hereinafter also referred to as heating return temperature) is equal to or higher than upper limit temperature Tmax. If the heating return temperature is lower than upper limit temperature Tmax (NO), the process proceeds to S4.

[0033] In S4, the controller 86 determines whether the heating amount of the burner 8 falls within a first heating amount range. The first heating amount range is a range of heating amounts below a first threshold heating amount Q1 (see FIG. 5). If the heating amount of the burner 8 falls within the first heating amount range (YES), the process proceeds to S6.

[0034] In S6, controller 86 determines whether the heating return temperature is equal to or greater than a first reference temperature T1. The first reference temperature T1 is a temperature lower than the upper limit temperature Tmax and is preset in accordance with the first heating amount range (see FIG. 5). If the heating return temperature is equal to or greater than the first reference temperature T1 (YES), the process proceeds to S16. If the heating return temperature is lower than the first reference temperature T1 (NO), the process proceeds to S18.

[0035] If the heating amount of the burner 8 does not fall within the first heating amount range in S4 (if NO), the process proceeds to S8. In S8, the controller 86 determines whether the heating amount of the burner 8 falls within the second heating amount range. The second heating amount range is a range of heating amounts that is equal to or greater than the first threshold heating amount Q1 and less than the second threshold heating amount Q2, and the second threshold heating amount Q2 is greater than the first threshold heating amount Q1 (see FIG. 5). If the heating amount of the burner 8 falls within the second heating amount range (if YES), the process proceeds to S10.

[0036] In S10, controller 86 determines whether the heating return temperature is equal to or greater than second reference temperature T2. Second reference temperature T2 is a preset temperature corresponding to the second heating amount range, and second reference temperature T2 is higher than first reference temperature T1 (see FIG. 5). If the heating return temperature is equal to or greater than second reference temperature T2 (YES), processing proceeds to S16. If the heating return temperature is lower than second reference temperature T2 (NO), processing proceeds to S18.

[0037] If the heating amount of the burner 8 does not fall within the second heating amount range in S8 (if NO), the process proceeds to S12. In S12, the controller 86 determines whether the heating amount of the burner 8 falls within the third heating amount range. The third heating amount range is a heating amount range that is equal to or greater than the second threshold heating amount Q2 and less than the third threshold heating amount Q3, and the third threshold heating amount Q3 is greater than the second threshold heating amount Q2 (see FIG. 5). If the heating amount of the burner 8 does not fall within the third heating amount range (if NO), the process proceeds to S18. If the heating amount of the burner 8 falls within the third heating amount range (if YES), the process proceeds to S14.

[0038] In S14, controller 86 determines whether the heating return temperature is equal to or greater than a third reference temperature T3. The third reference temperature T3 is a preset temperature corresponding to the third heating amount range, and is higher than the second reference temperature T2 (see FIG. 5). If the heating return temperature is equal to or greater than the third reference temperature T3 (YES), the process proceeds to S16. If the heating return temperature is lower than the third reference temperature T3 (NO), the process proceeds to S18.

[0039] As a result of S4-S14, the process proceeds to S16 if the heating amount of burner 8 and the heating return temperature fall within the gray range in the graph of Figure 5, and the process proceeds to S18 if the heating amount of burner 8 and the heating return temperature fall within the white range in the graph of Figure 5.

[0040] 3, in S16, if the timer count is not being performed, the controller 86 starts the timer count. As a result, the timer count value increases thereafter. After S16, the process proceeds to S20.

[0041] In S18, the controller 86 stops the timer count if it is currently being counted. This causes the timer count value to be maintained without being incremented thereafter. After S18, the process returns to S2.

[0042] In S20, the controller 86 determines whether the heating amount increase flag is on. If the heating amount increase flag is off (NO), the process proceeds to S22.

[0043] In S22, the controller 86 determines whether the timer count value has reached a first predetermined value (for example, 10 minutes). If the timer count value has not reached the first predetermined value (NO), the process returns to S2. If the timer count value has reached the first predetermined value (YES), the process proceeds to S24.

[0044] In S24, the controller 86 switches the heating amount increase flag from OFF to ON.

[0045] In S26, the controller 86 resets the timer count value. After S26, the process returns to S2.

[0046] If the heating amount increase flag is on in S20 (if YES), the process proceeds to S28. In S28, the controller 86 determines whether the timer count value has reached a second predetermined value (e.g., 30 seconds). If the timer count value has not reached the second predetermined value (e.g., 30 seconds) (if NO), the process returns to S2. If the timer count value has reached the second predetermined value (e.g., 30 seconds) (if YES), the process proceeds to S30.

[0047] In S30, the controller 86 increases the amount of heat generated by the burner 8 by a predetermined amount of heat.

[0048] In S32, the controller 86 resets the timer count value. After S32, the process returns to S2.

[0049] If the heating return temperature is equal to or higher than the upper limit temperature Tmax in S2 (YES), the controller 86 determines that the extinguishing condition is satisfied, and the process proceeds to S34 shown in Fig. 4. If a timer is counting at this point, the controller 86 stops the timer counting.

[0050] In S34, the controller 86 closes the flow rate control valve 38 to cut off the supply of fuel gas to the burner 8, thereby extinguishing the burner 8. Note that in S34, although the controller 86 extinguishes the burner 8, it continues to rotate the combustion fan 42, and cools each component part in the housing 4 by a so-called post fan.

[0051] In S36, the controller 86 waits until a predetermined time (e.g., 3 minutes) has elapsed since the burner 8 was extinguished in S34. When the predetermined time (e.g., 3 minutes) has elapsed since the burner 8 was extinguished (YES), the process proceeds to S38.

[0052] In S38, the controller 86 waits until the heating return temperature falls below a lower limit temperature Tmin. The lower limit temperature Tmin is a temperature lower than the first reference temperature T1. If the heating return temperature falls below the lower limit temperature Tmin in S38 (YES), the controller 86 determines that the re-ignition condition is met, and the process proceeds to S40.

[0053] In S40, the controller 86 opens the flow rate control valve 38 to resume the supply of fuel gas to the burner 8, and drives the igniter 50 to ignite the burner 8 again.

[0054] In S42, the controller 86 switches the heat increase flag off if it is on.

[0055] In S44, the controller 86 resets the timer count value. After S44, the process returns to S2 shown in FIG.

[0056] In the combustion heat source unit 2, when the burner heat amount increase process is started, if the heat amount of the burner 8 falls within a first heat amount range and the heating return temperature is equal to or higher than a first reference temperature T1, timing is performed using the timer count value (see S4, S6, S16). Then, when the timer count value reaches a first predetermined value (e.g., 10 minutes), the heating amount increase flag switches from OFF to ON (see S20, S22, S24, S26). Thereafter, if the state in which the heat amount of the burner 8 falls within the first heat amount range and the heating return temperature is equal to or higher than the first reference temperature T1 continues, timing is performed using the timer count value (see S4, S6, S16), and the heat amount of the burner 8 increases each time the timer count value reaches a second predetermined value (e.g., 30 seconds) (see S20, S28, S30, S32). When the heating amount of the burner 8 is increased so that it falls within the second heating amount range, and the heating return temperature is below the second reference temperature T2, timing using the timer count value is stopped (see S4, S8, S10, S18). When the heating amount of the burner 8 falls within the second heating amount range and the heating return temperature is equal to or higher than the second reference temperature T2, timing using the timer count value is restarted (see S4, S8, S10, S16). Each time the timer count value reaches a second predetermined value (e.g., 30 seconds), the heating amount of the burner 8 is further increased (see S20, S28, S30, S32). When the heating amount of the burner 8 is further increased so that it falls within the third heating amount range, and the heating return temperature is below the third reference temperature T3, timing using the timer count value is stopped (see S4, S8, S12, S14, S18). When the heating amount of the burner 8 enters the third heating amount range and the heating return temperature becomes equal to or higher than the third reference temperature T3, timing using the timer count value resumes (see S4, S8, S12, S14, S16). Each time the timer count value reaches a second predetermined value (e.g., 30 seconds), the heating amount of the burner 8 is further increased (see S20, S28, S30, S32). When the heating amount of the burner 8 enters the fourth heating amount range as a result of further increasing the heating amount of the burner 8, timing using the timer count value stops (see S4, S8, S12, S18). The fourth heating amount range is the range of heating amounts equal to or higher than the third threshold heating amount Q3 (see FIG. 5).

[0057] As described above, if the heating return temperature becomes equal to or exceeds the upper limit temperature Tmax while the heating amount of the burner 8 is being increased and the extinguishing condition is satisfied, the burner 8 is extinguished and cooling is performed by the post fan of the combustion fan 42 (see S2, S34). This allows each component part inside the housing 4 to be sufficiently cooled. If a predetermined time has passed since the burner 8 was extinguished and the heating return temperature falls below the lower limit temperature Tmin and the re-ignition condition is satisfied, the burner 8 is re-ignited (see S36, S38, S40).

[0058] Even if the heating amount of the burner 8 is increased as described above, the heating amount of the burner 8 may fall within the fourth heating amount range without the heating return temperature reaching or exceeding the upper limit temperature Tmax (i.e., without the burner 8 being extinguished). In this case, the heating amount of the burner 8 is high and the airflow generated by driving the combustion fan 42 is strong, so that each component within the housing 4 is sufficiently cooled.

[0059] (Variation) In the combustion heat source unit 2, the fuel gas flow path 34 that supplies fuel gas to the burner 8 and the combustion fan 42 that supplies combustion air to the burner 8 may be provided independently of each other, and the flow rate of the fuel gas supplied to the burner 8 and the flow rate of the combustion air supplied to the burner 8 may be adjusted separately. In this case, the controller 86 identifies the flow rate of the fuel gas supplied to the burner 8 via the fuel gas flow path 34, identifies the corresponding flow rate of the combustion air, and controls the rotation speed of the combustion fan 42, thereby adjusting the mixture ratio of air and fuel gas in the mixed gas to an appropriate mixture ratio according to the type of fuel gas.

[0060] The combustion heat source unit 2 does not necessarily have to include the liquid-liquid heat exchanger 52, the internal circulation path 54, the three-way valve 56, the heat exchanger outward path 58, the heat exchanger return path 60, the heat exchanger bypass path 62, the water volume servo valve 64, and the bypass servo valve 66. In this case, the combustion heat source unit 2 can perform heating operation, but cannot perform hot water supply operation.

[0061] The combustion heat source unit 2 may be provided with a burner for heating water for hot water supply, separate from the burner 8 for heating the heating medium. In this case, the combustion heat source unit 2 does not need to be provided with the liquid-liquid heat exchanger 52, the internal circulation path 54, and the three-way valve 56.

[0062] The combustion heat source unit 2 does not need to be equipped with the secondary heat exchanger 14. In this case, the downstream end of the burner outflow path 16 is connected to the upstream end of the primary heat exchanger 12. In this case, since no drain is generated, the drain pan 80, drain flow path 82, and drain piping 84 do not need to be provided.

[0063] 3 and 4, the determinations of S2, S6, S10, S14, and S38 may be made based on the temperature detected by the heating outgoing thermistor 32 (heating outgoing temperature) rather than the temperature detected by the heating return thermistor 30 (heating return temperature). The upper limit temperature Tmax used in the determination of S2, the first heating amount range used in the determination of S4, the first reference temperature T1 used in the determination of S6, the second heating amount range used in the determination of S8, the second reference temperature T2 used in the determination of S10, the third heating amount range used in the determination of S12, the third reference temperature T3 used in the determination of S14, the predetermined heating amount range used in the process of S30, and the lower limit temperature Tmin used in the determination of S38 may be set as appropriate to be different when control is performed based on the heating outgoing temperature from when control is performed based on the heating return temperature.

[0064] (Correspondence) The primary heat exchanger 12 and / or the secondary heat exchanger 14 are examples of heat exchangers. The heating medium is an example of a fluid. The heating return thermistor 30 or the heating forward thermistor 32 is an example of a temperature sensor.

[0065] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations set forth in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0066] 2: Combustion heat source machine 4: Housing 6: Combustion chamber 8: Burner 10: Exhaust duct 12 :Primary heat exchanger 14:Secondary heat exchanger 16: Outbound to Burna 18: Return to Barna 20: Circulation pump 22: Air supply pipe 24: Exhaust pipe 26: Heating return pipe 28: Heating return pipe 30: Heating return thermistor 32: Heating forward thermistor 34: Fuel gas flow path 36: Zero Governor 38: Flow control valve 40: Mixer 42: Combustion fan 44: Fuel gas supply pipe 46: Spark plug 48: Frame rod 50: Igniter 52:Liquid-liquid heat exchanger 52a: Heat transfer medium flow path 52b: Water channel 54: Internal circulation path 56: Three-way valve 58: Heat exchanger outbound 60: Heat exchanger return line 62: Heat exchanger bypass 64: Water volume servo valve 66: Bypass servo valve 68: Water supply pipe 70: Hot water pipe 72: Water supply flow sensor 74: Water supply thermistor 76: Heat exchanger outlet thermistor 78: Hot water thermistor 80: Drain pan 82: Drain passage 84: Drain piping 86: Controller

Claims

1. A combustion heat source machine, Housing and a burner contained within the housing; a combustion fan that supplies combustion air to the burner; a heat exchanger heated by combustion in the burner; a temperature sensor for detecting the temperature of a fluid flowing into or out of the heat exchanger; It has a controller, the controller is configured to drive the combustion fan when the burner is combusted; the rotation speed of the combustion fan when the burner is burning corresponds to the amount of heat generated by the burner, The controller is configured to increase the heating amount of the burner so that the heating amount of the burner falls within a second heating amount range that is higher than the first heating amount range when the heating amount of the burner is within a first heating amount range and the temperature detected by the temperature sensor exceeds a first reference temperature corresponding to the first heating amount range.

2. The controller extinguishing the burner when an extinguishing condition is satisfied that the temperature detected by the temperature sensor exceeds an upper limit temperature that is higher than the first reference temperature; The combustion heat source machine according to claim 1 , wherein the combustion fan continues to be driven even after the extinguishing condition is satisfied and the burner is extinguished.

3. The combustion heat source machine according to claim 2 , wherein the controller is configured to re-ignite the burner when a predetermined time has elapsed after the extinguishing condition is satisfied and the burner is extinguished.

4. The combustion heat source machine according to claim 3, wherein the controller is configured not to re-ignite the burner even after the predetermined time has elapsed after the extinguishing condition has been satisfied and the burner has been extinguished, unless a re-ignition condition is satisfied in which the temperature detected by the temperature sensor falls below a lower limit temperature that is lower than the first reference temperature.

5. a circulation pump for sending the fluid to the heat exchanger; The controller When the burner is combusted, the circulation pump is driven; The combustion heat source machine according to claim 2 , wherein the circulation pump continues to be driven even after the extinguishing condition is satisfied and the burner is extinguished.

6. The combustion heat source machine according to claim 1, wherein the controller is configured to increase the heating amount of the burner so that the heating amount of the burner falls within a third heating amount range higher than the second heating amount range when the heating amount of the burner is within the second heating amount range and the temperature detected by the temperature sensor exceeds a second reference temperature corresponding to the second heating amount range and higher than the first reference temperature.

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