JP4222271B2 - Combustion control method for hot water heating system - Google Patents

Description

  The present invention relates to a combustion control method in a hot water heating type hot water heating system in which hot water combusted and heated by a heat source unit is circulated with a heating terminal, and in particular, ON-OFF generated during proportional combustion control in the heat source unit. This relates to a combustion control method capable of reducing the repetition frequency (for example, the number of ON-OFF times per hour).

  Conventionally, as a combustion control of combustion equipment, in addition to setting a range that can be continuously operated as the combustion amount of the oil fan heater, it is also possible to perform intermittent combustion with a minimum combustion amount lower than the minimum combustion amount within the combustion range Is known (see, for example, Patent Document 1). In this case, if the minimum switch is turned on by the user or the continuous operation with the minimum combustion amount is started, the operation is shifted to the intermittent combustion operation with the minimum combustion amount unconditionally, thereby realizing energy saving. I am trying to let you. The conversion of the combustion state between the minimum combustion amount and the continuous combustion amount range is performed not by changing the amount of fuel but by adjusting the amount of combustion air.

JP 2000-28135 A

  By the way, in the above hot water heating system, since high temperature water having a predetermined temperature supplied from the heat source machine to the heating terminal is radiated by the heating terminal, the heating is performed. The hot water circulation is performed in which the low-temperature water is heated to a predetermined temperature by the heat source unit and the high-temperature water is supplied to the heating terminal again. For this reason, in the combustion control in the heat source unit of the hot water heating system, the temperature of the low temperature water returned from the heating terminal (return side temperature) is supplied to the heating terminal as high temperature water having a predetermined temperature after heat exchange heating. The amount of combustion is changed and controlled. In other words, if the heat source unit is in combustion, the heat exchanger is set so that the temperature of the high-temperature water (outside temperature) supplied from the heating heat exchanger and supplied to the heating terminal becomes a predetermined target temperature. Proportional combustion control is performed in a predetermined proportional combustion range (for example, a range of Pmin to Pmax in FIG. 2 (b)) depending on the return-side temperature to be returned (the magnitude of the temperature difference between the return-side temperature and the output-side temperature). Executed.

  For example, as shown in FIG. 6, hot water circulation is started (step S101), and if the outlet side temperature is lower than a predetermined temperature, ignition is performed and combustion is started (YES in step S102, step S103). The proportional combustion control in the proportional combustion range is performed according to the height (step S104). As long as the hot water temperature after heating does not reach an upper limit temperature that is too high when heated further (YES in step S105), or unless a safety device is activated and an error occurs due to the occurrence of another abnormality (in step S106). NO), combustion based on the proportional combustion control is continued. On the other hand, if the hot water temperature after the heating reaches the upper limit temperature, the combustion is stopped (NO in step S105, step S108), and the combustion is resumed when the outlet side temperature decreases to the predetermined lower limit temperature after the combustion stops. (YES in step S102, step S103). That is, the ON-OFF combustion operation (repetitive operation of ignition and extinguishing of the heat source machine) is performed so that the outlet temperature is maintained within a predetermined constant temperature range. In short, the proportional combustion operation as described above is performed in the ON combustion state while performing the ON-OFF combustion operation.

  However, when there are a plurality of heating terminals to which high-temperature water is supplied from the heat source unit, switching from two or more heating operation states to only one heating operation state, or only one heating terminal However, if the heating load (necessary amount of heat at the heating terminal) suddenly decreases to a low load state, such as when the heating capacity is switched from “strong” to “weak”, Because the amount of heat of the high-temperature water becomes excessive and the outlet temperature rises, continuous combustion occurs at the minimum combustion point Pmin within the above-mentioned proportional combustion range, and combustion stops even when the outlet temperature exceeds the above upper limit temperature. Will be. And if the outlet side temperature falls to the above lower limit temperature, it is ignited again and burned, but it rises to the above upper limit temperature in a short time and the combustion is stopped in a short time. The ON-OFF combustion operation is repeated.

  If this happens, the frequency at which combustion is once stopped and then re-ignited (for example, the number of fire extinguishing / ignition repeated per unit time) increases, and in proportion to the increase in the frequency of ignition and the like, During the slight time difference from fuel injection (for example, fuel gas injection) to ignition, the amount of fuel that is unnecessarily discharged increases, or noise accompanying fire extinguishing / ignition (igniter operation noise, fuel supply Inconveniences such as an increase in valve opening / closing operation noise and the like. That is, when the heating load is low, there is a disadvantage that the efficiency of heat conversion (thermal efficiency or heating efficiency) with respect to fuel consumption is reduced or noise is increased.

  On the other hand, the minimum combustion point Pmin of the proportional combustion range described above may cause overheating (decrease in durability) of the combustion tube constituting the burner of the heat source machine if it is continuously burned in a lower combustion state, or may cause backfire. There is a situation in which the lower limit value is set so as not to cause the inconvenience of inviting and the safety factor is set, and the minimum combustion point Pmin cannot be lowered unnecessarily.

  The present invention has been made in view of such circumstances, and its purpose is to reduce thermal efficiency while suppressing overheating of the heat source device even when the demand on the heating terminal side is low load. It is an object of the present invention to provide a combustion control method capable of reducing the frequency of ON / OFF of combustion so as to avoid noise and increase noise.

  In order to achieve the above-mentioned purpose, when the hot water is circulated between the heat source device and the heating terminal so that the hot water heated from the heat source device is supplied to the heating terminal and the warm water after heat radiation from the heating terminal is returned to the heat source device. The heat source is burned when the temperature of the hot water supplied from the heat source device to the heating terminal is within a predetermined temperature range, and the temperature of the hot water supplied from the heat source device to the heating terminal is set to the predetermined temperature. The following invention has been created for a combustion control method of a hot water heating system in which the combustion amount of the heat source machine is proportionally controlled according to the hot water temperature returned to the machine.

  In the first invention, as the proportional combustion control, a normal proportional control mode in which proportional combustion is performed in a normal proportional combustion range set as a combustion amount capable of continuous combustion, and the minimum side is lower than the minimum combustion amount in the normal proportional combustion range. An extended proportional control mode in which proportional combustion is performed in an extended proportional combustion range in which an extended minimum combustion amount is set is switchable. And, when execution of proportional combustion control in the normal proportional control mode is selected, in a state where the combustion is stopped by the temperature of the hot water supplied from the heat source unit to the heating terminal side becoming higher than the temperature range. ON-OFF combustion cycle time from the start of combustion when the hot water temperature becomes lower than the above temperature range as it is circulated until the combustion is restarted after the combustion is stopped due to the hot water temperature becoming higher than the above temperature range However, when it becomes shorter than the setting switching time, the combustion mode is switched to the proportional combustion control in the extended proportional control mode (claim 1).

  In the case of this first aspect, when proportional combustion control is being executed in the normal proportional control mode, the heating load, which is the required amount of heat on the heating terminal side, fluctuates to a low load state, resulting in ON-OFF combustion. Even if the cycle time is shortened and the frequency at which ON-OFF combustion is repeated is likely to increase, the duration of the combustion ON state when the combustion is turned ON by switching to the extended proportional control mode as described above Becomes longer. That is, since proportional combustion is possible on the side lower than the minimum combustion amount in the normal proportional combustion range in the normal proportional control mode, the hot water temperature after heating becomes higher than the predetermined temperature range until the combustion is stopped. It is possible to further increase the duration of the combustion ON state. As a result, the ON-OFF combustion cycle time becomes longer, the increase in the repetition frequency of ON-OFF combustion is avoided, and the frequency of ON-OFF combustion can be reduced. By reducing the frequency of this ON-OFF combustion, wasteful fuel consumption repeated every time of fire extinguishing / igniting and generation of operating noise can be suppressed to avoid a decrease in thermal efficiency and avoid an increase in noise. become.

  In the second invention, as the proportional combustion control, a normal proportional control mode in which proportional combustion is performed in a normal proportional combustion range set as a combustion amount capable of continuous combustion, and the minimum side is lower than the minimum combustion amount in the normal proportional combustion range. An extended proportional control mode in which proportional combustion is performed in an extended proportional combustion range in which an extended minimum combustion amount is set is switchable. When execution of proportional combustion control in the normal proportional control mode is selected, the temperature of the hot water supplied from the heat source unit to the heating terminal is detected and the temperature rise per unit time is monitored. When the degree of temperature rise exceeds the preset temperature rise degree even when proportional combustion is performed with the minimum combustion amount in the normal proportional combustion range, switching to proportional combustion control in the extended proportional control mode is performed (claim) Item 2).

  Also in the case of the second aspect of the invention, when proportional combustion control is being executed in the normal proportional control mode, the heating load, which is the required amount of heat on the heating terminal side, fluctuates to a low load state, resulting in ON-OFF Even if the combustion cycle time is shortened and the frequency of repeated ON-OFF combustion is likely to increase, the combustion ON state is maintained when the combustion is turned on by switching to the extended proportional control mode as described above. The time can be made longer. As a result, as in the first aspect of the invention, the ON-OFF combustion cycle time becomes longer, the increase in the repetition frequency of ON-OFF combustion is avoided, and the frequency of combustion ON-OFF can be reduced. Become. By reducing the frequency of this ON-OFF combustion, wasteful fuel consumption repeated every time of fire extinguishing / igniting and generation of operating noise can be suppressed to avoid a decrease in thermal efficiency and avoid an increase in noise. become. In particular, in the case of the second invention, switching to the extended proportional control mode has suddenly changed so that the degree of temperature rise per unit time (for example, the immediately preceding temperature rise rate or the immediately preceding temperature rise amount) exceeds the set temperature rise degree. Therefore, it is possible to grasp the switching timing more accurately than in the case of the first invention in which the switching is performed based on the ON-OFF combustion cycle time, and the frequency of ON-OFF combustion is increased. If it is likely to increase, it becomes possible to switch to the extended proportional control mode more quickly. As a result, it is possible to promote the reduction of the frequency of ON-OFF combustion, and more actively avoid the decrease in thermal efficiency and the increase in noise.

  In the first invention or the second invention described above, when switching to execution of proportional combustion control in the extended proportional control mode, the combustion amount is lower than the minimum combustion amount in the normal proportional combustion range within the extended proportional combustion range. Integration of the time for proportional combustion in the range on the side is started, and when the integrated time exceeds the set maximum time, it is possible to return to the proportional combustion control in the original normal proportional control mode. 3). By doing so, overheating, etc., especially for the combustor (burner) of the heat source unit due to continued combustion in a range lower than the minimum combustion amount of the normal proportional combustion range for a long time is suppressed. Or it becomes possible to avoid. As a result, it is possible to obtain the operation of the first or second invention without causing a decrease in durability of the heat source device.

  The same action can be obtained without returning to the proportional combustion control in the original normal proportional control mode as described above. That is, air supply means for supplying combustion air to the heat source device in a variable supply amount is provided, and when switching to execution of proportional combustion control in the extended proportional control mode, within the extended proportional combustion range, When integration of the proportional combustion time is started in a range lower than the minimum combustion amount of the normal proportional combustion range, and the integrated time exceeds the set maximum time, the air supply amount by the air supply means is temporarily (4). In this case, the combustor of the heat source unit is cooled by increasing the air supply amount, thereby suppressing or avoiding overheating.

  In the first invention or the second invention described above, flame temperature detection means for detecting the flame temperature of the combustion flame is provided in the heat source unit, and the mode is switched to execution of proportional combustion control in the extended proportional control mode. The flame temperature detected by the flame temperature detecting means is monitored, and when the flame temperature exceeds the set flame temperature, it is possible to return to the proportional combustion control in the original normal proportional control mode. (Claim 5). By doing so, the overheating of the heat source machine, particularly the combustor, is more directly caused by the combustion in the range lower than the minimum combustion amount in the above normal proportional combustion range for a long time. Can be suppressed or avoided. That is, it becomes possible to predict the occurrence of overheating more directly by monitoring the flame temperature, and the effects of the first or second invention can be obtained while more reliably avoiding a decrease in durability of the heat source unit. It becomes possible.

  In the case of the method by monitoring the flame temperature, the same operation can be obtained without returning to the proportional combustion control in the original normal proportional control mode. That is, a flame temperature detecting means for detecting the flame temperature of the combustion flame and an air supply means for supplying combustion air in a variable supply amount are provided for the heat source unit, and proportional combustion control by the extended proportional control mode is provided. When the flame temperature is detected, the flame temperature detected by the flame temperature detecting means is monitored, and when the flame temperature exceeds the set flame temperature, the air supply amount by the air supply means is temporarily increased. (Claim 6). In this case, based on more direct predictions such as overheating by monitoring the flame temperature, the air supply amount is increased at an appropriate timing to cool the combustor of the heat source unit, thereby generating overheating. It is possible to appropriately suppress or avoid the above.

  As described above, according to the combustion control method for a hot water heating system according to any one of claims 1 to 6, when the proportional combustion control is executed in the normal proportional control mode, the required heat amount on the heating terminal side Even if the heating load is fluctuated to a low load state, the ON-OFF combustion cycle time is shortened and the frequency of repeated ON-OFF combustion is likely to increase. By switching to, the duration of the combustion ON state when combustion is turned on can be made longer, and the ON-OFF combustion cycle time can also be made longer. Thereby, increase of the repetition frequency of ON-OFF combustion can be avoided and the frequency of ON-OFF of combustion can be reduced. And by this frequency reduction, it is possible to avoid wasteful fuel consumption repeated every time of fire extinguishing / ignition and operation noise generation, avoiding a decrease in thermal efficiency and avoiding an increase in noise.

  In particular, according to the combustion control method of the hot water heating system according to claim 2, it is possible to accurately grasp the switching timing to the extended proportional control mode, and if the frequency of ON-OFF combustion is likely to increase, It is possible to switch to the extended proportional control mode more quickly. Accordingly, it is possible to promote the reduction of the frequency of ON-OFF combustion, and more actively avoid the decrease in thermal efficiency and the increase in noise.

  According to the third aspect of the present invention, it is possible to suppress or avoid the occurrence of overheating of the heat source machine, particularly the combustor, caused by the combustion in the range lower than the minimum combustion amount in the normal proportional combustion range for a long time. Therefore, it is possible to avoid a decrease in durability of the heat source machine.

  According to claim 4, it is possible to cool the combustor of the heat source unit by increasing the air supply amount, so that the forced proportional control mode is not forcedly returned to the normal proportional control mode as in claim 3. In addition, it is possible to suppress or avoid the occurrence of overheating.

  According to claim 5, overheating can be predicted more directly by monitoring the flame temperature, and combustion in a range lower than the minimum combustion amount of the normal proportional combustion range is continued for a long time. It is possible to more directly suppress or avoid the occurrence of overheating of the heat source machine, particularly the combustor, due to the above, and it is possible to avoid a decrease in durability of the heat source machine.

  According to the sixth aspect of the present invention, the air supply amount can be increased at a more appropriate timing based on a more direct prediction such as occurrence of overheating by monitoring the flame temperature, and the combustion of the heat source unit can be performed by the increased air. The vessel can be cooled. Thus, it is possible to more appropriately suppress or avoid the occurrence of overheating without forcibly returning from the extended proportional control mode to the normal proportional control mode.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows an example of a hot water circulation type hot water heating system in which the combustion control method of the present invention is implemented. The hot water heating system includes a heat source device 2 and a heating terminal 4 connected to the heat source device 2 by a hot water circulation pipe 3. In addition, although the example of the single function heat source machine 2 specialized in a warm water heating function is shown in FIG. 1 as a heat source machine which comprises a warm water heating system, it is not restricted to this, Both a hot-water supply function and a warm water heating function are shown. Of course, it is also possible to configure the hot water heating system of the present invention using the combined heat source machine provided, or the combined heat source machine provided with a hot water supply function, a hot water heating function and a bath reheating function.

  The heat source unit 2 includes a burner 21 that constitutes a combustor, a heat exchanger 22 that is heat-exchanged and heated by the combustion heat of the burner 21, and a fuel supply system 23 that supplies fuel (fuel gas) to the burner 21. And a blower fan 24 as air supply means for supplying combustion air to the burner 21, a hot water circulation path 25 passing through the heat exchanger 22, and a controller 5 for controlling various operations of the heat source unit 2. ing. The burner 21 and the heat exchanger 22 constitute a heating unit in the heat source machine.

  The fuel supply system 23 includes a fuel supply pipe 231, an electromagnetic on-off valve 232 that opens and closes the fuel supply pipe 231 to switch fuel supply and supply stop, and a fuel supply amount to the burner 21 through the fuel supply pipe 231. And an electromagnetic proportional valve 233 for changing and adjusting (fuel gas supply amount).

  The hot water circulation path 25 is connected to the downstream end of the return pipe 31 of the hot water circulation pipe 3 and is connected to a return path 253 that reaches the heat exchanger 22 via an expansion tank 251 and a circulation pump 252 that are interposed in the middle. A hot water outlet 254 connected from the exchanger 22 to the upstream end of the outgoing pipe 32 of the hot water circulation pipe 3 is provided. The expansion tank 251 is connected to the downstream end of the water injection path 26, and the inside of the expansion tank 251 is maintained at a constant water level by water injection at the time of installation performed through the water injection path 26 and subsequent supplementary water. ing. In addition, what is necessary is just to perform this constant water level maintenance by the water supplement control by the controller 5 based on the detection signal from a high water level switch and a low water level switch, for example.

  When the circulation pump 251 is operated, the hot water in the expansion tank 251 is sent to the heat exchanger 22 through the return path 253, and the hot water that has exited the heat exchanger 22 is sent to the heating terminal through the hot water supply path 254 and the outgoing pipe 32. Hot water circulation is performed in which the hot water that has been supplied to 41 and radiated by the heating terminal 41 is returned to the expansion tank 251 through the return pipe 31 and the return path 253 again. At this time, the hot water temperature (exit temperature) immediately after exiting the heat exchanger 22 is detected by the high temperature thermistor 256 and output to the controller 5. The high temperature thermistor 256 serves as temperature detecting means for detecting the temperature of hot water supplied from the heat source device 2 to the heating terminal 41 side.

  A low temperature thermistor 257 is provided in the return path 253 closer to the heat exchanger 22 than the circulation pump 252, and the low temperature thermistor 257 returns to the burner 21 regardless of whether the combustion is stopped or not. The side temperature is detected and output to the controller 5. In addition, the code | symbol 255 in the figure is a bypass path, and this bypass path 255 returns to the expansion tank 251 without supplying the hot water from the hot water supply path 254 to the heating terminal 41, and the heating terminal 41 (the heating terminal 42 mentioned later is referred to). Including).

  Here, when the hot water from the heat source device 2 is circulated to two types of heating terminals, a high-temperature heating terminal and a low-temperature heating terminal, the heating terminal 41 is used as a high-temperature heating terminal, and the low-temperature heating terminal 42 is supplied with a low temperature. A pipe for circulating water may be attached. For example, the hot water in the expansion tank 251 is supplied to the low temperature heating terminal 42 through the low temperature side piping 33 branched from the return channel 253 between the circulation pump 252 and the heat exchanger 22, and the hot water after heat radiation is returned to the return piping. What is necessary is just to join the return piping 31 through 34 and to return to the expansion tank 251. Examples of the high-temperature heating terminal include, for example, a bathroom dryer and an indoor heater. In a normal heating operation, a relatively high temperature (for example, 80 ° C.) is supplied to radiate heat. Examples of the low-temperature heating terminal include a floor heating heat dissipating panel and a heat dissipating tube installed in each room of a building. During normal heating operation, hot water having a relatively low temperature (for example, 60 ° C.) is used. Receives heat and dissipates heat. In FIG. 1, one high temperature heating terminal 41 and one low temperature heating terminal 42 are shown, but two or more are provided, respectively, so that hot water as a heat source is circulated and supplied from one heat source unit 2 to them. May be.

  The controller 5 receives various operation commands based on an input operation by a user or the like from the remote controller 51 and performs heating control or the like by circulating hot water, and includes a microcomputer or a memory in which a predetermined operation program is incorporated. It has been done. The heating control is realized by combustion control based on the operation control of the circulation pump 252 and the operation control of the fuel supply system 23, the burner 21, the blower fan 24, and the like.

<First Embodiment>
The basis of the combustion control executed by the controller 5 for the above hot water heating system is to perform proportional combustion control of the combustion of the burner 21. Here, the proportional combustion control is to burn at a combustion amount at which the outlet temperature after combustion heating becomes a predetermined target temperature (for example, 80 ° C. or 80 ° C. or higher) depending on the detected return side temperature. In other words, when the temperature is raised to the target temperature, the burner 21 is proportionally burned with a combustion amount proportional to the temperature difference between the target temperature and the return side temperature. In addition, even when only proportional combustion control is used, the hot water temperature detected by the high temperature thermistor 256 exceeds a predetermined upper limit temperature (fire extinguishing temperature) due to fluctuations in the heating load on the heating terminals 41 and 42 side, etc. In addition, ON-OFF combustion control is also performed in which combustion is stopped and ignition is restarted and combustion is restarted when the hot water temperature falls to a predetermined lower limit temperature (ignition temperature). In this embodiment, as the proportional combustion control, in addition to the normal proportional control mode in which proportional combustion is performed in the normal proportional combustion range, an extended proportional range in which the minimum side is expanded to a lower side than the normal proportional combustion range. The proportional combustion control section is also incorporated in the controller 5 so as to provide an extended proportional control mode in which proportional combustion is performed with the two, and to switch between these two control modes according to the combustion state.

  That is, as shown in FIG. 2A, the proportional combustion control unit stores and holds a table X that is set in advance so that a predetermined air-fuel ratio is obtained in the relationship between the fuel amount (gas amount) and the air amount (air amount). is doing. In the normal proportional control mode, combustion that can be heated by the above temperature difference from the normal proportional combustion range from the maximum combustion point (maximum combustion amount) Pmax to the minimum combustion point (minimum combustion amount) Pmin on the table X in FIG. A control value corresponding to the quantity is selected and combustion control is performed. On the other hand, in the extended proportional control mode, a control value corresponding to the combustion amount that can be heated by the temperature difference is selected from the extended proportional combustion range of the maximum combustion point Pmax to the extended minimum combustion point Ps on the table X in FIG. Combustion control is performed. That is, in the extended proportional control mode, the minimum side of the proportional combustion range is extended from Pmin to the extended minimum combustion point (extended minimum combustion amount) Ps that is lower than Pmin, compared to the normal proportional control mode. The proportional combustion control is executed. The minimum combustion point Pmin in the normal proportional combustion range is set to a minimum combustion amount that does not cause overheating of the combustion pipe of the burner 21 even if continuous combustion is performed at the minimum combustion point Pmin.

  The switching between the normal proportional control mode and the extended proportional control mode is performed by switching the ON-OFF combustion cycle time (ON combustion state after ignition and then the combustion is stopped and switched to the OFF combustion state. , The period until ignition is performed again) and the combustion continuous time at the extended minimum combustion point Ps. That is, the normal proportional control mode is switched to the extended proportional control mode when the ON-OFF combustion cycle time is equal to or shorter than the predetermined set switching time, while the proportional combustion control in the extended proportional control mode is performed more than the minimum combustion point Pmin. When the continuous combustion time on the lower side exceeds the set maximum time, the expansion proportional control mode is forcibly switched to the normal proportional control mode.

  Hereinafter, it will be described in detail with reference to the flowchart of FIG. 3 and the time chart of FIG.

  When the heating switch of the remote controller 51 is turned on by the user, the heating operation is turned on, whereby first the operation of the circulation pump 252 is started (step S1), and the detected temperature Td of the high temperature thermistor 256 is higher than the ignition temperature Tn. After confirming that it is low, ignition control of the burner 21 is performed (YES in step S2, step S3). As said ignition temperature Tn, the temperature of the range of 60 to 66 degreeC is set, for example. Then, after confirming that the ON-OFF combustion cycle time Ft is longer than the set switching time α, proportional combustion control in the normal proportional control mode is performed (step S5). As a result, the burner 21 is proportionally combusted in the normal proportional combustion range Pmax to Pmin based on the hot water temperature detected by the low temperature thermistor 257 and the target temperature, and the hot water heated to the target temperature from the heat exchanger 22 is heated. The heating terminal 41 is circulated and supplied.

  For example, 5 minutes is set as the setting switching time Ft. In other words, a time value that does not fall too many times, such as the frequency of ON-OFF combustion cycle per hour (12 times (60 minutes / 5 minutes = 12 times)) is set as the setting switching time Ft. ing.

  The proportional combustion control in the normal proportional control mode is continued continuously (NO in step S7, NO in step S4) as long as the detected temperature Td of the high temperature thermistor 256 does not become higher than the fire extinguishing temperature Tf (YES in step S6). YES, step S5). If an abnormality occurs in this process and the safety device is activated, safe operation (combustion stop and heating operation stop) is executed, and an error display is displayed on the remote controller 51 (YES in step S7). , Step S8).

  On the other hand, the detected temperature Td becomes higher than the fire extinguishing temperature Tf during the proportional combustion control (NO in step S6), the combustion is stopped (step S11), and the process returns to step S2. As a case where such a situation occurs, for example, when the heating operation intensity at the heating terminal 41 is switched from “strong” to “weak” by the user, the amount of heat of the high-temperature water that is rapidly supplied and circulated is reduced. As a result, the return side temperature may become higher than before. Note that when there are two or more heating terminals 41, the heating operation with two or more heating terminals 41 may occur even when the number of operating terminals is suddenly reduced, for example, only one.

  Then, if the combustion stop (combustion OFF) state continues (NO in step S2) and the detected temperature Td becomes lower than the ignition temperature Tn (YES in step S2), combustion is resumed by ignition control again ( Step S3). In this case, since the ON-OFF combustion cycle time Ft is longer than the set switching time α (YES in step S4), proportional combustion control in the normal proportional control mode is performed as described above.

  However, if the heating load remains in a low load state as described above, the detected temperature Td exceeds the fire extinguishing temperature Tf early (see time t1 in FIG. 4) (NO in step S6), and combustion stop control is performed. (Step S11) switches to the combustion OFF state. Then, the detected temperature Td is lowered by this combustion OFF, ignition is performed again, and combustion is started (YES in step S2, step S3). When the ON-OFF combustion cycle time Ft (see FIG. 4) becomes equal to or shorter than the set switching time α (NO in step S4), the normal proportional control mode is switched to the extended proportional control mode. The combustion of the burner 21 is controlled by the proportional combustion control in the extended proportional combustion range Pmax to Ps (step S9). When the mode is switched to the extended proportional control mode, proportional combustion is possible in the range from the minimum combustion point Pmin of the normal proportional combustion range until then to the extended minimum combustion point Ps lower than that, so the combustion ON duration t2 (See FIG. 4) also becomes longer accordingly. As a result, even if the heating load is maintained at a low load state, the ON-OFF combustion cycle time can be lengthened, and the number of ON-OFF combustion (frequency of ON-OFF combustion) generated per hour is reduced. can do.

  Simultaneously with the switching control from the normal proportional control mode to the extended proportional control mode, the cumulative time of proportional combustion in the range of the extended minimum combustion point Ps which is lower than the minimum combustion point Pmin of the normal proportional combustion range is integrated. The accumulated time t3 (see FIG. 4) is monitored (step S10). Then, after confirming that the accumulated time t3 does not exceed the set maximum time β (YES in step S10), as long as the detected temperature Td of the high temperature thermistor 256 is not higher than the fire extinguishing temperature Tf as described above ( While the combustion ON is continued (NO in step S7, NO in step S4, NO in step S9), the combustion is turned off when Td becomes higher than Tf (time t2 in FIG. 4). The combustion is turned off at the elapsed time), and the ignition is re-ignited after the warm water temperature is lowered (NO in step S6, steps S11, S2 to S4, and step S9).

  If the accumulated time t3 exceeds the set maximum time β in this process (NO in step S10), the process is forcibly switched back to the proportional combustion control in the normal proportional control mode in step S5. As a result, it is possible to avoid the inconvenience of lowering durability due to overheating of the burner 21 due to continuous combustion at the extremely low extended minimum combustion point Ps. Therefore, the set maximum time β is a time value (for example, 5 minutes) that does not cause inconveniences that affect the durability of the burner 21 due to the continuous combustion at the extended minimum combustion point Ps. ) Is set.

  As described above, even if the heating load is in a low load state, it is possible to suppress or avoid an increase in the frequency of ON-OFF combustion to avoid a decrease in thermal efficiency, and to overheat the burner 21 of the heat source unit 2 or It is possible to prevent the occurrence of backfire and to avoid a decrease in durability.

Second Embodiment
FIG. 5 shows a flowchart of the combustion control according to the second embodiment of the present invention. This second embodiment differs from the first embodiment only in that a temperature increase rate Rd described later is adopted as a switching trigger from the normal proportional control mode to the extended proportional control mode, and the other points are the first. This is the same as the embodiment.

  In the controller 5 of the second embodiment, the temperature rise rate Rd (the rate of temperature rise per unit time, that is, the degree of temperature rise) is obtained by calculation in response to the output of the detected temperature of the high temperature thermistor 256, and the controller 5 of the second embodiment. It is updated and stored, and during the heating operation, it is monitored whether or not the temperature increase rate Rd exceeds a set increase rate Rs described later.

  When the heating operation is turned on, the start of the operation of the circulation pump 252 (step S21) and the execution of the ignition control of the burner 21 after confirming that the detected temperature Td of the high temperature thermistor 256 is lower than the ignition temperature Tn ( YES in step S22, step S23) is performed in the same manner as steps S1 to S3 (see FIG. 3) of the first embodiment.

  Then, after confirming that the detected temperature Td is lower than the target temperature Tt (YES in step S24), proportional combustion control in the normal proportional control mode is performed in the same manner as in step S5 of the first embodiment (step S25). ). This proportional combustion control in the normal proportional control mode continues continuously (NO in step S27, YES in step S24, YES in step S25) as long as the detected temperature Td does not become higher than the fire extinguishing temperature Tf (YES in step S26). ). In addition, it is the same as in the first embodiment in that it is a condition that safe driving and error display are not executed by the operation of the safety device (YES in step S27, step S28).

  On the other hand, when the detected temperature Td becomes higher than the fire extinguishing temperature Tf during the proportional combustion control (NO in step S26), the combustion is stopped (step S32). Then, the process returns to the above step S22, waits for the return side temperature to decrease, performs ignition control again, and resumes the proportional combustion control in the normal proportional control mode (YES in step S22, YES in step S23, step S24, step S25). That is, ON-OFF combustion starts from continuous combustion.

  In the above process, ignition has been performed (step S23), but if the detected temperature Td exceeds the target temperature Tt (NO in step S24), the immediately preceding temperature increase rate Rd is checked (step S29), and is normally proportional. It is determined whether to perform proportional combustion control in the control mode or the extended proportional control mode. That is, if the temperature increase rate Rd remains below the set temperature increase rate Rs, the normal proportional control mode is continued (NO in step S29, step S25), and the temperature increase rate Rd exceeds the set temperature increase rate Rs. Then, the extended proportional control mode is selected, that is, the mode is switched to the extended proportional control mode (YES in step S29, step S30). When switched to the extended proportional control mode, the combustion of the burner 21 is controlled by the proportional combustion control in the extended proportional combustion range Pmax to Ps, and from the minimum combustion point Pmin of the normal proportional combustion range up to that point. Proportional combustion in the range up to a low extended minimum combustion point Ps is possible, so that the combustion ON duration t2 (see FIG. 4) is increased by that amount as in the first embodiment. Even if the load is maintained at a low load state, the ON-OFF combustion cycle time can be lengthened, and the number of ON-OFF combustion (frequency of ON-OFF combustion) generated per hour can be reduced.

  The significance of switching to the extended proportional control mode triggered by the above-described temperature rise rate Rd exceeding the set temperature rise rate Rs will be described below. The proportional combustion state in the normal proportional control mode is switched from continuous combustion to ON-OFF combustion, and the ON-OFF combustion cycle time is shortened, as described in the first embodiment. It is in a low load state, indicating that the return side temperature tends to be higher than that in the high load state. As the proportional combustion amount with respect to the return side temperature, the combustion amount on the minimum side of the normal proportional combustion range is selected, and finally the combustion state at the minimum combustion point Pmin is continued. However, even if the combustion state is set at the lowest combustion point Pmin that is the lowest in the normal proportional combustion range, the outlet temperature after heat exchange heating in the heat exchanger 22 gradually becomes higher and reaches the target temperature Tt (for example, 80 ℃). At this time, if the heating load suddenly changes to a lower load side, that is, if the required heat quantity suddenly changes to a lower side, the outlet side temperature exceeds the fire extinguishing temperature Tf at an early stage and is switched to combustion OFF. The OFF combustion cycle time is shortened, and the frequency of ON-OFF combustion is increased.

  Such a sudden change to the low load side of the heating load that causes an increase in the frequency of ON-OFF combustion is grasped at an early stage by checking the change in the temperature increase rate as described above, and is quickly switched to the expansion proportional control mode. Therefore, the frequency of ON-OFF combustion can be surely reduced as compared with the case of the first embodiment. That is, in the case of the first embodiment, the switching to the extended proportional control mode is performed based on the ON-OFF combustion cycle time. However, in the case of the second embodiment, since the temperature rise rate is used in the case of the second embodiment, it is determined quickly that the switching condition is established almost instantaneously. To get. Therefore, as the set temperature increase rate Rs, the value of the temperature increase rate corresponding to the low load side fluctuation of the heating load that causes the frequency of the ON-OFF combustion cycle to increase too frequently is set. Has been.

  Note that if the integrated time t3 exceeds the set maximum time β after switching to the extended proportional control mode, it is forcibly switched to proportional combustion control in the normal proportional control mode (NO in step S30, step S25), and the extended minimum Similar to the first embodiment, it is possible to avoid the inconvenience of deterioration in durability due to overheating of the burner 21 due to continuous combustion at the combustion point Ps.

<Other embodiments>
The present invention is not limited to the first and second embodiments described above, but includes other various embodiments. That is, in the first and second embodiments, overheating of the burner 21 of the heat source unit 2 is performed by forcibly switching from the extended proportional control mode to the normal proportional control mode when the accumulated time t3 exceeds the set maximum time β. However, the present invention is not limited to this, and instead of forcibly switching from the extended proportional control mode to the normal proportional control mode, the extended proportional control mode can be used even if the accumulated time t3 exceeds the set maximum time β. Proportional combustion control is continued as it is, and the rotational speed of the blower fan 24 is temporarily increased until the predetermined time (predetermined cooling period) elapses from when the set maximum time β is exceeded. The air volume) may be increased by a predetermined amount, and the burner 21 may be cooled by a cooling function using the increased air. For example, the combustion at the point indicated by Psa in FIG.

  In the first and second embodiments, the forced switching from the extended proportional control mode to the normal proportional control mode is performed on condition that the integrated time t3 exceeds the set maximum time β. Not limited to this, a flame temperature detecting means (for example, a thermocouple) for detecting the flame temperature of the combustion flame is provided in the burner 21 of the heat source machine, and the forced switching from the extended proportional control mode to the normal proportional control mode is performed. You may make it carry out on condition that the flame temperature detected by a detection means exceeds preset flame temperature. In other words, the occurrence of overheating of the burner 21 of the heat source apparatus is directly detected by the above-described flame temperature detection, and switching to the extended proportional control mode is performed when the flame temperature at which overheating is expected is reached. It is. Also based on the detection of the flame temperature, if the flame temperature exceeds the set flame temperature, the normal time until the predetermined time elapses from the time when the flame temperature is exceeded without returning to the normal proportional control mode, as described above. Meanwhile, the air fan (air volume) may be temporarily increased by increasing the rotational speed of the blower fan 24, and the burner 21 may be cooled by the increased air cooling function. That is, for example, the combustion at the point indicated by Psa in FIG.

  Furthermore, in the second embodiment, switching from the normal proportional control mode to the extended proportional control mode is performed based on the temperature increase rate Rd. However, the present invention is not limited to this. A temperature rise amount per time (for example, a temperature rise amount per 0.1 sec or 1.0 sec) may be used, and switching may be performed when this temperature rise amount becomes equal to or greater than the set temperature rise amount on the plus side. That is, the switching may be performed according to the level of the temperature increase per unit time, such as the temperature increase rate or the temperature increase amount.

It is a lineblock diagram showing an example of a hot water heating system to which an embodiment of the present invention is applied. The proportional combustion control range in the relationship between the fuel amount (gas amount) and the combustion air (air amount) is shown. FIG. 2A shows that of the present embodiment, and FIG. 2B shows the conventional one. It is a flowchart of a 1st embodiment. It is a time chart which shows the change of a combustion state along the flow chart of a 1st embodiment. It is a flowchart of a 2nd embodiment. It is a flowchart which shows the example of the combustion control method currently performed conventionally.

Explanation of symbols

2 Heat source machine 4 Heating terminal 5 Controller (proportional combustion control unit)
21 Burner 22 Heat exchanger 23 Fuel supply system 24 Blower fan (air supply means)
25 Hot water circuit 256 High temperature thermistor (temperature detection means)

Claims (6)

When supplying hot water heated from the heat source device to the heating terminal and circulating the hot water between the heat source device and the heating terminal so that the warm water after heat radiation from the heating terminal is returned to the heat source device, the heating terminal side from the heat source device When the temperature of the hot water supplied to the heating source is within a predetermined temperature range, the heat source machine is burned, and the temperature of the hot water supplied from the heat source machine to the heating terminal is returned to the heat source machine so that the temperature is returned to the heat source machine. A combustion control method for a hot water heating system that proportionally controls the combustion amount of a heat source unit in response,
As the above proportional combustion control, the normal proportional control mode in which proportional combustion is performed in the normal proportional combustion range set as the combustion amount capable of continuous combustion, and the extended minimum combustion amount lower than the minimum combustion amount in the normal proportional combustion range is set as the minimum side. The extended proportional control mode for performing proportional combustion in the extended proportional combustion range is provided to be switchable,
When execution of proportional combustion control in the normal proportional control mode is selected, the hot water supplied from the heat source unit to the heating terminal side is circulated in a state where combustion is stopped when the temperature is higher than the temperature range. As the hot water temperature becomes lower than the above temperature range, the ON-OFF combustion cycle time from the start of combustion to the restart of combustion through the combustion stop due to the hot water temperature becoming higher than the above temperature range, A combustion control method for a hot water heating system, wherein when the set switching time is shorter than the set switching time, switching to proportional combustion control in the extended proportional control mode is performed. When supplying hot water heated from the heat source device to the heating terminal and circulating the hot water between the heat source device and the heating terminal so that the warm water after heat radiation from the heating terminal is returned to the heat source device, the heating terminal side from the heat source device When the temperature of the hot water supplied to the heating source is within a predetermined temperature range, the heat source machine is burned, and the temperature of the hot water supplied from the heat source machine to the heating terminal is returned to the heat source machine so that the temperature is returned to the heat source machine. A combustion control method for a hot water heating system that proportionally controls the combustion amount of a heat source unit in response,
As the above proportional combustion control, the normal proportional control mode in which proportional combustion is performed in the normal proportional combustion range set as the combustion amount capable of continuous combustion, and the extended minimum combustion amount lower than the minimum combustion amount in the normal proportional combustion range is set as the minimum side. The extended proportional control mode for performing proportional combustion in the extended proportional combustion range is provided to be switchable,
When execution of proportional combustion control in the normal proportional control mode is selected, the temperature of the hot water supplied from the heat source unit to the heating terminal side is detected and the temperature rise per unit time is monitored. When the temperature rise degree exceeds the set temperature rise degree even when proportional combustion is performed with the minimum combustion amount in the normal proportional combustion range, the proportional combustion control in the extended proportional control mode is switched. Combustion control method for a hot water heating system. It is a combustion control method of the hot water heating system according to claim 1 or 2,
When switching to execution of proportional combustion control in the extended proportional control mode, integration of the time for proportional combustion in the range of the extended proportional combustion range that is lower than the minimum combustion amount in the normal proportional combustion range is started. And
A combustion control method for a hot water heating system, wherein when the integrated time exceeds a set maximum time, the proportional combustion control is restored to the original normal proportional control mode. It is a combustion control method of the hot water heating system according to claim 1 or 2,
Air supply means for supplying combustion air with a variable supply amount is provided in the heat source unit,
When switching to execution of proportional combustion control in the extended proportional control mode, integration of the time for proportional combustion in the range of the extended proportional combustion range that is lower than the minimum combustion amount in the normal proportional combustion range is started. And
A combustion control method for a hot water heating system, wherein the air supply amount by the air supply means is temporarily increased when the integrated time exceeds a set maximum time. It is a combustion control method of the hot water heating system according to claim 1 or 2,
Flame temperature detection means for detecting the flame temperature of the combustion flame is provided in the heat source machine,
When switching to execution of proportional combustion control in the extended proportional control mode, the flame temperature detected by the flame temperature detecting means is monitored,
A combustion control method for a hot water heating system, wherein when the flame temperature exceeds a set flame temperature, the proportional combustion control is restored to the original normal proportional control mode. It is a combustion control method of the hot water heating system according to claim 1 or 2,
A flame temperature detecting means for detecting the flame temperature of the combustion flame and an air supply means for supplying combustion air in a variable supply amount are provided for the heat source unit,
When switching to execution of proportional combustion control in the extended proportional control mode, the flame temperature detected by the flame temperature detecting means is monitored,
A combustion control method for a hot water heating system, wherein when the flame temperature exceeds a set flame temperature, an air supply amount by the air supply means is temporarily increased.

Images