JP6398504B2 - Heat source machine - Google Patents

Description

  The present invention relates to a heat source machine, and more particularly to control at the start of combustion of a heat source machine having a combustion mechanism for burning sprayed liquid fuel.

  Conventionally, a heat source machine having a combustion mechanism for burning liquid fuel represented by kerosene has been used. For example, a hot water supply apparatus that uses an oil burner as a combustion mechanism and heats tap water with the oil burner is a typical example.

  Generally, the amount of heat generated in the heat source unit is controlled by the amount of fuel sprayed in the combustion mechanism. In a combustion mechanism, generally, when the amount of fuel is small, fuel spray becomes unstable. For this reason, in a region where the amount of generated heat is low, so-called on-off combustion control is used, in which a combustion period by spraying with a certain amount of fuel that can stably perform fuel spraying and a combustion stop period in which fuel spraying is stopped are alternately provided. ing.

  For example, Japanese Patent Laid-Open No. 2002-31334 (Patent Document 1) discloses a heat source that switches between proportional combustion control that continuously performs spray combustion of liquid fuel with a fuel amount corresponding to a required amount of heat and the on-off combustion control. The machine is listed. In the heat source machine described in Patent Document 1, control for preventing chattering sufficiently when switching from proportional combustion control to on-off combustion control is described.

JP 2002-31334 A

  Generally, in a heat source machine that burns sprayed fuel, when starting combustion from a combustion stopped state, combustion control is performed to control the amount of fuel according to a predetermined pattern suitable for ignition in order to reliably ignite the sprayed fuel. Is done.

  On the other hand, if the sprayed fuel adheres to a low temperature portion of the combustion mechanism, there is a possibility that the user may perceive an odor due to generation of unburned HC (hydrocarbon). For this reason, in order to reduce unburned HC, it is preferable to raise the temperature of the combustion mechanism early at the time of ignition.

  However, if the amount of fuel at the time of ignition is set excessively for an early temperature rise, the amount of generated heat becomes excessive, which may adversely affect the control of the tapping temperature. In particular, in the above-described on-off combustion control, the combustion period and the combustion stop period are automatically provided alternately, so that the frequency of ignition due to the start of combustion increases. Therefore, it is important to optimize the combustion control at the time of ignition. .

  The present invention has been made to solve such problems, and an object of the present invention is to appropriately control combustion at the start of combustion of a heat source machine having a combustion mechanism for burning sprayed liquid fuel. To do.

According to the present invention, the heat source device includes a combustion mechanism that generates combustion heat by burning the sprayed liquid fuel, and a control device that controls the combustion mechanism. The control device includes a calculation unit, a first control unit, and an ignition control unit. The calculation unit calculates the required combustion amount. The first control unit adjusts the ratio of the combustion period and the combustion stop period by on / off control that automatically and alternately provides the combustion period of the combustion mechanism and the combustion stop period of the combustion mechanism at a constant combustion amount, thereby requesting the required combustion amount. To control the combustion heat. The ignition control unit controls the amount of combustion in the combustion mechanism according to a predetermined ignition pattern when starting the combustion operation of the combustion mechanism. Further, the ignition control unit increases the amount of combustion in the ignition pattern when the combustion operation is started in response to detection of the minimum operating flow rate than when the combustion operation is started from the combustion stop state by the on / off control. Configured to do.

  According to the heat source device, the combustion amount at the start of combustion can be appropriately controlled when the on / off control is applied in which the combustion start frequency is increased by the ignition pattern by alternately providing the combustion period and the combustion stop period. Specifically, at the first ignition according to the detection of the minimum operating flow rate (MOQ), the amount of combustion in the ignition pattern is increased to raise the temperature of the portion where the sprayed fuel adheres early, thereby causing unburned fuel. The generation of HC can be suppressed, and at the time of the second and subsequent ignition accompanying the application of on / off control, it is possible to prevent excessive combustion heat at the start of combustion.

  Preferably, the control device further includes a second control unit and a control mode selection unit. The second control unit controls the combustion heat according to the required combustion amount by proportional combustion control that adjusts the combustion amount in a continuously provided combustion period. The control mode selection unit selects the on / off control by the first control unit when the required combustion amount is smaller than a predetermined value, while the proportionality by the second control unit when the required combustion amount is larger than the predetermined value. Select combustion control. Further, when the proportional combustion control is selected when the combustion operation is started in response to the detection of the minimum operation flow rate, the ignition control unit may start the combustion operation from the on-off control combustion stop state. In comparison, the amount of combustion in the ignition pattern is increased.

  In this way, even when proportional combustion control in which the combustion period is continuously provided is applied, the amount of combustion in the ignition pattern is increased at the first ignition in response to detection of the minimum operating flow rate (MOQ). Generation of unburned HC can be suppressed.

  Preferably, the combustion mechanism includes an injection nozzle for spraying the liquid fuel and a burner cone disposed around the spray port of the liquid fuel by the injection nozzle. The control device further includes a temperature estimation unit for estimating the temperature of the burner cone when the combustion operation is started. When the estimated burner cone temperature is higher than the predetermined temperature, the ignition control unit performs combustion in the ignition pattern at the start of the combustion operation in response to detection of the minimum operating flow rate, compared to when the temperature is lower than the predetermined temperature. Configured to reduce the amount.

  In this way, at the high temperature of the burner cone where unburned HC is not generated even if the sprayed fuel adheres, the combustion heat for heating the burner cone at an early stage is unnecessary, so the amount of combustion in the ignition pattern is reduced. Decrease. Thereby, generation | occurrence | production of the excess combustion heat in an ignition pattern can further be avoided, Therefore Combustion at the time of a combustion start can be controlled more appropriately.

  More preferably, the temperature estimation unit estimates the burner cone temperature based on an elapsed time since the combustion mechanism stopped the previous combustion operation. Or a temperature estimation part estimates the temperature of a burner cone based on the combustion in a combustion mechanism, and a combustion stop log | history.

  In this way, it is possible to determine whether or not the burner cone has a temperature at which unburned HC is not generated (whether or not it is a high temperature) based on the operation history of the combustion mechanism without disposing a temperature sensor. .

  Preferably, the ignition pattern is defined by a first initial combustion amount supplied before ignition and a second initial combustion amount supplied for a predetermined time after the ignition is confirmed. The ignition control unit increases or decreases the amount of combustion in the ignition pattern by adjusting the second initial combustion amount.

  In this way, the optimal amount of fuel that takes into account the ignitability is uniformly set as the amount of combustion until ignition is performed, while the combustion mechanism (burner cone) is quickly increased by increasing the amount of combustion after the ignition is confirmed. The amount of heat for heating can be secured. This makes it possible to control the amount of combustion at the start of combustion so as to achieve both ensuring ignitability and increasing the temperature of the combustion mechanism (burner cone) for preventing the generation of unburned HC.

  Preferably, the heat source device further includes a blower fan configured to supply an air amount corresponding to the rotational speed to the combustion mechanism. The control device further includes a fan rotation speed control unit for controlling the rotation speed of the blower fan in correspondence with the amount of sprayed fuel in the combustion mechanism. The fan rotation speed control unit includes a first period during which the blower fan rotates at a first rotation speed corresponding to the ignition pattern and a first rotation speed between the stop of the combustion operation and the restart of the combustion operation. The rotational speed of the blower fan is controlled so as to provide a second period during which the blower fan rotates at a lower second rotational speed. Further, the first period is provided after the second period.

  In this case, when the operation of the blower fan is continued in preparation for the restart of the combustion from the stop of the combustion operation to the restart of the combustion operation, the rotation speed of the blower fan is set to the first rotation corresponding to the ignition pattern. Compared with the case where it maintains to a number, the temperature fall in a heat source machine can be suppressed. As a result, it is possible to improve the thermal efficiency in the heat source machine after the combustion is resumed.

  More preferably, when the combustion operation is stopped in response to the non-detection of the minimum operating flow rate, the fan rotation speed control unit sets the rotation speed of the blower fan until a predetermined post purge time elapses after the combustion operation is stopped. When the minimum operating flow rate is detected again before the post-purge time elapses, the rotational speed of the blower fan is increased to the first rotational speed. When the minimum operating flow rate is detected again before the post-purge time elapses, the ignition control unit is in a state where the rotation speed of the blower fan is controlled at the first rotation speed by the fan rotation speed control unit. Then, fuel combustion in the combustion mechanism is started.

  In this way, when the combustion operation is stopped in response to the non-detection of the minimum operating flow rate (MOQ off), the rotation speed of the blower fan is set during the post-purge period in which the blower fan continues to operate in preparation for resuming combustion. It can be lower than the first rotational speed corresponding to the ignition pattern. As a result, it is possible to suppress a temperature drop in the heat source device as compared with the case where the rotational speed of the blower fan during the post-purge period is maintained at the first rotational speed.

  Alternatively, preferably, when the on-off control is selected and the combustion operation is stopped in accordance with the end of the combustion period, the fan rotation speed control unit is configured to supply air during the first time period from the start of the combustion stop period. The rotational speed of the fan is controlled to the second rotational speed, and the rotational speed of the blower fan is increased to the first rotational speed until the combustion stop period ends after the elapse of the first time.

  In this case, when the combustion operation is automatically stopped in accordance with the end of the combustion period in the on / off control, the rotation speed of the blower fan is set to the first rotation speed corresponding to the ignition pattern in the first half of the combustion stop period. Can also be reduced. As a result, it is possible to suppress a temperature drop in the heat source machine as compared with the case where the rotation speed of the blower fan is maintained at the first rotation speed throughout the combustion stop period.

  More preferably, the fan rotation speed control unit variably controls the second rotation speed and the first time according to the length of the combustion stop period adjusted according to the required combustion amount in the on / off control.

  In this way, the rotation speed (second rotation speed) of the blower fan in the first half of the combustion stop period can be returned to the first rotation speed by the end of the combustion stop period (start of the next combustion period). And can be reduced as much as possible. Thereby, the temperature fall in the heat source machine in a combustion stop period can further be suppressed.

  According to the present invention, it is possible to appropriately perform the combustion control at the start of combustion of the heat source machine having the combustion mechanism for burning the sprayed liquid fuel.

It is a block diagram explaining the schematic structure of the hot water supply apparatus comprised including the heat-source equipment according to this Embodiment. It is a block diagram for demonstrating in detail the structure of the combustion burner shown by FIG. 3 is a functional block diagram for illustrating combustion control of a combustion burner (combustion mechanism) according to Embodiment 1. FIG. It is a wave form diagram which shows the operation example of the combustion burner in proportional combustion control. It is a wave form diagram which shows the operation example of the combustion burner in on-off combustion control. It is a wave form diagram for demonstrating the ignition pattern at the time of the ignition by an ignition control part. 5 is a flowchart illustrating combustion control of the combustion burner according to the first embodiment. 6 is a flowchart for illustrating a processing sequence of ignition control according to the first embodiment. It is a wave form diagram for demonstrating the ignition pattern at the time of the first ignition by an ignition control part. 6 is a flowchart illustrating combustion control of a combustion burner according to a second embodiment. 10 is a flowchart for illustrating a processing sequence of ignition control according to the second embodiment. It is a conceptual diagram which shows the 1st example of the change of the count value increased / decreased by temperature estimation. It is a conceptual diagram which shows the 2nd example of the change of the count value increased / decreased by temperature estimation. It is a functional block diagram explaining the structure for fan rotation speed control according to Embodiment 3. It is a conceptual wave form diagram for demonstrating the comparative example of the fan speed control at the time of a combustion start and the time of a combustion stop. It is a conceptual wave form diagram for demonstrating fan rotation speed control according to Embodiment 3 at the time of the combustion stop according to MOQ OFF. It is a conceptual wave form diagram for demonstrating fan rotation speed control according to the comparative example at the time of the combustion stop by on-off combustion control. FIG. 11 is a conceptual waveform diagram for illustrating fan rotation speed control according to the third embodiment when combustion is stopped in on-off combustion control. 10 is a first flowchart illustrating fan rotation speed control when combustion is stopped in a heat source device according to Embodiment 3. FIG. FIG. 12 is a second flowchart illustrating fan rotation speed control when combustion is stopped in the heat source device according to the third embodiment.

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

[Embodiment 1]
FIG. 1 is a block diagram illustrating a schematic configuration of a hot water supply apparatus 10 configured to include a heat source device according to the present embodiment.

  Referring to FIG. 1, a hot water supply device 10 includes a combustion can body 6, a combustion burner 7, an ignition transformer 78, a blower fan 8, a water inlet pipe 11, a heat exchanger 12, a hot water outlet pipe 16, an exhaust pipe. A smoke cylinder 30 and a controller 100 are included. In the configuration example of FIG. 1, the heat source device according to the present embodiment can be configured by the combustion burner 7, the blower fan 8, and the controller 100 in the hot water supply device 10.

  The water intake pipe 11 is connected to a water pipe, for example, and is configured to input tap water to the heat exchanger 12 as a heating medium. The injection nozzle 70 of the combustion burner 7 is disposed on the upper portion of the combustion can body 6.

  The combustion burner 7 is constituted by, for example, a gun type burner having an injection nozzle 70 that sprays petroleum (kerosene) as liquid fuel. The combustion burner 7 further includes an electromagnetic open / close valve 71, an electromagnetic supply pump 72, a fuel supply pipe 73, a return pipe 74, an oil temperature detection sensor 75, and a flow rate control valve 76. The combustion burner 7 corresponds to an example of a “combustion mechanism”. The blower fan 8 supplies combustion air to the combustion burner 7.

  The fuel sprayed from the injection nozzle 70 is mixed with the combustion air from the blower fan 8. By being ignited by the ignition transformer 78, the fuel from the injection nozzle 70 is burned and a flame is generated. The combustion heat generated by the flame from the combustion burner 7 is given to the heat exchanger 12 in the fuel can body 6. On the downstream side of the combustion can body 6 in the flow direction of the combustion gas, a smoke exhaust cylinder 30 for exhausting the exhaust gas after heat exchange is opened.

  The heat exchanger 12 heats the tap water from the inlet pipe 11 flowing through the heat exchanger 12 by the combustion heat from the combustion burner 7. Hot water heated by the heat exchanger 12 is discharged from the currant 15 or the like via the hot water discharge pipe 16.

  The inlet pipe 11 is provided with a temperature sensor 17 for detecting the incoming water temperature Tw (° C.) and a flow rate sensor 18 for detecting the water flow rate Q (l / m). The tapping pipe 16 is provided with a temperature sensor 19 for detecting a tapping temperature Th (° C.).

FIG. 2 is a block diagram for explaining the configuration of the combustion burner 7 in detail.
Referring to FIG. 2, the fuel supply pipe 73 guides liquid fuel (hereinafter also simply referred to as fuel) from a fuel tank (not shown) to the injection nozzle 70. An electromagnetic on-off valve 71 and an electromagnetic supply pump 72 are interposed in the fuel supply pipe 73.

  The electromagnetic open / close valve 71 opens and closes in response to a control command So from the controller 100 in order to turn on / off fuel supply from a fuel tank (not shown) to the fuel supply pipe 73. The electromagnetic supply pump 72 boosts the fuel supplied via the open electromagnetic on-off valve 71 in accordance with a control command Sp from the controller 100. The fuel whose pressure has been increased by the electromagnetic supply pump 72 is injected from the injection nozzle 70 in the form of a mist.

  The return pipe 74 is disposed so as to return a part of the liquid fuel supplied from the fuel supply pipe 73 to the fuel supply pipe 73. In the example of FIG. 2, the return pipe 74 is configured to return the fuel downstream of the electromagnetic opening / closing valve 71 and upstream of the electromagnetic supply pump 72.

  The return pipe 74 includes an oil temperature detection sensor 75 for detecting the oil temperature of the return oil, a flow rate control valve 76 for controlling the flow rate of the return oil, and a check valve 77 for preventing the back flow of the return oil. Is intervening.

The valve opening degree of the flow control valve 76 is adjusted according to the control command Sv from the controller 100. The amount of fuel sprayed from the injection nozzle 70 (hereinafter also simply referred to as “fuel amount”) is controlled by adjusting the flow rate of the return oil by the flow rate control valve 76. Basically, the amount of combustion by the combustion burner 7 is proportional to the amount of fuel. Therefore, the amount of combustion by the combustion burner 7 can be controlled by controlling the valve opening degree of the flow control valve 76.

  A burner cone 80 is disposed around the fuel spray port by the injection nozzle 70. Therefore, part of the fuel sprayed from the injection nozzle 70 may adhere to the burner cone 80 due to the structure. The burner cone 80 is provided with a plurality of holes (not shown) for introducing the combustion air supplied from the blower fan 8. A flame is formed in each hole by burning the air-fuel mixture of the introduced air and the fuel evaporated after spraying. When the amount of combustion increases, a diffusion flame is formed to the outside of the burner cone 80.

  If the fuel sprayed from the injection nozzle 70 adheres at a low temperature of the burner cone 80, there is a risk that the odor due to the generation of unburned HC may be perceived by the user. On the other hand, when the temperature of the burner cone 80 is increased, the attached fuel is immediately vaporized, so that the problem of odor due to generation of unburned HC hardly occurs.

  Referring to FIG. 1 again, the controller 100 is constituted by a microcomputer, for example. The controller 100 controls the operation of the hot water supply device 10 according to a user operation. For example, the user operation includes an on / off instruction for hot water supply operation and a set temperature for hot water supply. As a representative function, the controller 100 generates a combustion control command to the combustion burner 7 such that the tapping temperature Th is controlled according to the set temperature Tr. The combustion control command includes the control commands So, Sp, Sv shown in FIG. By controlling the combustion heat by the combustion burner 7 in accordance with the combustion control command, the hot water temperature Th in the hot water supply apparatus 10 is controlled.

  FIG. 3 is a functional block diagram for illustrating the combustion control of the combustion burner 7 according to the first embodiment. As for the function of each block shown in each functional block diagram including FIG. 3, a circuit (hardware) having the function may be configured in the controller 100, or the controller 100 according to a preset program. May be realized by executing software processing.

  Referring to FIG. 3, the controller 100 includes a number calculation unit 110 and a combustion control unit 120. The combustion control unit 120 includes an on / off combustion control unit 130, a proportional combustion control unit 140, an ignition control unit 150, and a control mode selection unit 160.

  The number calculation unit 110 calculates a required number Rg based on the set temperature Tr, the incoming water temperature Tw, the tapping temperature Th, and the flow rate Q. The required number Rg corresponds to the amount of generated heat required for the combustion burner 7.

  In general, the number in the required number = 1 (No. 1) means the amount of heat necessary to raise the flow rate of Q = 1 (L / min) by 25 (° C.). Therefore, the theoretical calorific value (number) Rg * necessary for increasing the water temperature in the hot water supply apparatus 10 can be set according to the following equation (1), for example.

Rg * = (Tr−Tc) · Q / 25 (1)
In the formula (1), (Tr−Tc) corresponds to a target temperature increase amount in the heat exchanger 12. The above Rg * is calculated by the product of the target temperature increase amount and the flow rate Q.

  Furthermore, it is also possible to set the required number Rg by further combining feedback control of the temperature difference (Tr−Th) between the tapping temperature Th and the set temperature Tr. In this case, Rg * is set according to the sum of the number calculated according to Equation (1) and the number based on the PI control of the temperature deviation (Tr-Th).

  The requested number Rg is set in consideration of the actual thermal efficiency η in the hot water supply apparatus 10 (for example, Rg = Rg * / η). The thermal efficiency η is defined by the ratio of the amount of heat received by the heated medium to the amount of combustion heat by the combustion burner 7. As an example, in a non-latent heat recovery type hot water supply apparatus, η = about 0.8, and in a latent heat recovery type hot water supply apparatus, η = about 0.9. The thermal efficiency η may be a fixed value obtained in advance by experiments or the like, or may be a value that is sequentially learned based on the temperature and fuel amount during operation.

  The combustion control unit 120 controls the combustion burner 7 so that the combustion burner 7 generates combustion heat according to the required number Rg calculated by the number calculation unit 110 according to the operation on / off command of the hot water supply device 10. Control So, Sp, Sv. For example, when the hot water supply device 10 is turned on, the combustion burner 7 is activated when the flow rate Q of the hot water supply device 10 exceeds a predetermined minimum operating flow rate (MOQ). On the other hand, when the flow rate Q becomes lower than the minimum operating flow rate (MOQ) during the operation of the combustion burner 7 or when the operation of the hot water supply device 10 is turned off, the operation of the combustion burner 7 is stopped. When the combustion burner 7 is stopped, combustion is also stopped.

  For example, the minimum operating flow rate (MOQ) is the minimum at which the hot water supply device 10 can operate stably without causing inaccuracies in detection by the flow rate sensor 18 or inconvenience that boiling occurs in the heat exchanger 12. It is preset as a flow rate.

  During the operation of the combustion burner 7, the combustion control unit 120 sets the combustion number Gs in the combustion burner 7 so that the combustion burner 7 can generate an amount of heat corresponding to the required number Rg. The amount of fuel sprayed from the injection nozzle 70 is controlled according to the combustion number Gs set according to the required number Rg. That is, in the following description, the combustion number Gs in the combustion burner 7 is a parameter proportional to the amount of fuel sprayed from the injection nozzle 70. The control commands So, Sp, Sv of the combustion burner 7 are set so that the fuel amount according to the combustion number Gs is injected.

  In the present embodiment, when the combustion burner 7 is operated, the on / off combustion control by the on / off combustion control unit 130 and the proportional combustion control by the proportional combustion control unit 140 are selectively applied.

  A mode of combustion operation in proportional combustion control and on-off combustion will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a waveform diagram showing an operation example of the combustion burner in the proportional combustion control, and FIG. 5 is a waveform diagram showing an operation example of the combustion burner 7 in the on-off combustion control.

  Referring to FIG. 4, in the proportional combustion control, fuel spray from injection nozzle 70 is continuously executed. That is, the combustion in the combustion burner 7 is continued and the combustion period is continuously provided. Further, the combustion number Gs is continuously adjusted according to the required number Rg.

  For example, the combustion number Gs is sequentially set in proportion to the required number Rg set in consideration of thermal efficiency. Further, the amount of fuel sprayed from the injection nozzle 70 is adjusted in proportion to the combustion number Gs mainly by the control command Sv.

  According to the proportional combustion control, the amount of fuel sprayed from the injection nozzle 70 changes according to the required number Rg. For this reason, it is necessary to reduce the amount of fuel sprayed from the injection nozzle 70 in the region where the required number Rg is small. However, in a region where the amount of fuel is low, the spraying form from the injection nozzle 70 becomes unstable, making it difficult to control the combustion heat.

  Therefore, in the heat source apparatus according to the present embodiment, the on / off combustion control shown in FIG. 5 is applied in a region where the required number Rg is small, as in Patent Document 1.

  Referring to FIG. 5, in the on / off combustion control, during the operation of combustion burner 7, a combustion period in which fuel is injected and a combustion stop period in which fuel injection is stopped are alternately provided. In the example of FIG. 5, combustion periods are provided after times t0 to t1, t2 to t3, and t4. In each combustion period, the combustion number Gs is set to a constant value Gon. The combustion number Gon is set in a region where the combustion spray mode by the injection nozzle 70 is stable.

  On the other hand, the supply of fuel from the injection nozzle 70 is stopped in each of the combustion stop periods between the times t1 and t2 and between t3 and t4.

  In the on-off combustion control, the combustion burner 7 generates the combustion period by controlling the ratio Kt (Kt = Toff / Ton) of the combustion period length Ton where the combustion number Gs = Gon and the combustion stop period length Toff where Gs = 0. The combustion heat generated is controlled.

  The substantial combustion number Gs * in the on-off combustion control is given by the following equation (2). By modifying equation (2), the ratio Kt can be obtained according to equation (3) by setting the combustion number Gs * according to the required number Rg. In the on / off combustion control, Gs * <Gon.

Gs * = Gon · Ton / (Ton + Toff) (2)
Kt = (Gon / Gs *) − 1 (3)
In general, the ratio Kt is controlled so as to control the combustion stop period length Toff after fixing the combustion period length Ton.

  Referring to FIG. 3 again, control mode selection unit 160 selects one of on / off combustion control and proportional combustion control in accordance with required number Rg calculated by number calculation unit 110. For example, proportional combustion control is selected in a region where the required number Rg is large, while on-off combustion control is selected in a region where the required number Rg is small.

  When the on / off combustion control is selected, the ratio Kt for obtaining the combustion number Gs * corresponding to the required number Rg is particularly set so that the on / off combustion control unit 130 realizes the combustion mode as shown in FIG. Control commands So, Sp, Sv are generated so as to be realized. The on / off combustion control unit 130 corresponds to a “first control unit”.

  When the proportional combustion control is selected, the proportional combustion control unit 140 sets the control commands So, Sp, and Sv so that the fuel amount is sprayed continuously according to the combustion number Gs that is proportional to the required number Rg. Generate. The proportional combustion control unit 140 corresponds to a “second control unit”.

  At the start of combustion from the combustion stopped state, that is, at the time of ignition, the ignition control unit 150 controls the combustion in any control mode. The ignition control unit 150 controls the combustion number Gs in the combustion burner 7, that is, the amount of fuel sprayed from the injection nozzle 70, according to a predetermined ignition pattern. Therefore, at the start of combustion accompanied by ignition of the combustion burner 7, the combustion number Gs in the combustion burner 7 is controlled according to the ignition pattern regardless of the required number Rg.

  FIG. 6 is a conceptual waveform diagram for explaining an example of an ignition pattern at the time of ignition by the ignition control unit 150.

Referring to FIG. 6, when the start of combustion is instructed from the combustion stopped state at times t0, t2, and t4 in FIGS. 4 and 5, the combustion number Gs is set at a predetermined rate up to the first initial combustion number Ga. Is raised at. When the amount of fuel corresponding to the combustion number Gs = Ga is reached, the sprayed fuel is ignited by the ignition transformer 78 (FIG. 1).

  When flame is detected by a flame detection sensor (not shown) at time ta, the combustion number Gs changes at a predetermined rate up to the second initial combustion number Gb. At time tb = tb, the combustion number Gs reaches the second initial combustion number Gb. The combustion number Gs is maintained at the second initial combustion number Gb for a predetermined period Tc.

  When the predetermined period Tc elapses from time tb, the ignition pattern is terminated at time tc. After completion of the ignition pattern, the combustion number Gs changes at a constant rate toward the combustion number (FIGS. 4 and 5) set by the on-off combustion control or the proportional combustion control.

  Thus, at the start of combustion, priority is given to the reliable ignition of the fuel, and the ignition control unit 150 gives the combustion number Gs according to the ignition pattern shown in FIG. 6 regardless of the required number Rg at that time. To control.

  FIG. 7 is a flowchart illustrating combustion control of combustion burner 7 according to the first embodiment. In the following, it is assumed that the processing in each step of the flowchart including FIG. 7 is executed by software processing and / or hardware processing by the controller 100.

  When the flow rate Q exceeds the minimum operating flow rate (MOQ) with the operation of the hot water supply device 10 turned on, the controller 100 detects MOQ on and starts the operation of the combustion burner 7. The controller 100 repeatedly executes the control process according to the flowchart shown in FIG.

  In step S110, the controller 100 calculates the required number Rg based on the current set temperature Tr, incoming water temperature Tw, outgoing hot water temperature Th, and flow rate Q. That is, the processing in step S110 corresponds to the function of the number arithmetic unit 110 in FIG.

  In step S120, the controller 100 compares the request number Rg calculated in step S110 with a predetermined determination value Rt. When Rg> Rt (YES in S120), that is, when the required number Rg is relatively large, the controller 100 advances the process to step S130.

  In step S130, the controller 100 controls the combustion heat generated by the combustion burner 7 by the proportional combustion control described with reference to FIG. As described above, when the proportional combustion control is applied, the combustion number Gs in the combustion burner 7 is set according to the required number Rg.

  In contrast, when Rg ≦ Rt (NO in S120), that is, when the required number Rg is relatively small, the controller 100 proceeds to step S140. In step S140, the controller 100 controls the combustion heat generated by the combustion burner 7 by the on-off combustion control described with reference to FIG. As described above, when the on / off combustion control is applied, the combustion number Gs in the combustion burner 7 alternates between the combustion period (Gs = Ton) and the combustion stop period (Gs = 0) according to the ratio Kt according to the required number Rg. Is set to repeat.

  That is, the process in step S120 corresponds to the function of the control mode selection unit 160 in FIG. 3, the process in step S130 corresponds to the function of the proportional combustion control unit 140 in FIG. 3, and the process in step S140 is the on-off combustion in FIG. This corresponds to the function of the control unit 130.

  In step S160, the controller 100 determines whether or not it is a combustion start time. In step S160, a YES determination is made at the time of instructing combustion start in response to detection of the minimum operating flow rate (MOQ on). Further, step S160 is also determined as YES at the time of instructing automatic combustion start from the combustion stop period during application of on-off combustion control. In the example of FIGS. 4 and 5, step S160 is determined as YES at each of times t0, t2, and t4.

  On the other hand, if the start of combustion is not instructed, including during combustion of the combustion burner 7, step S160 is NO.

  The controller 100 skips the process of step S200 when it is not at the start of combustion (when NO is determined in S160). In this case, the operation of the combustion burner 7 is controlled according to the combustion number Gs set in steps S130 to S140.

  On the other hand, at the start of combustion (when YES is determined in step S160), the controller 100 proceeds to step S200 and executes ignition control. In the ignition control, the combustion number Gs of the combustion burner 7 is controlled according to a predetermined ignition pattern.

  FIG. 8 is a flowchart for explaining the processing sequence of the ignition control shown in step S200. FIG. 8 shows a processing portion related to setting of the fuel amount (combustion number) among the functions performed by the ignition control unit 150.

  Referring to FIG. 8, in step S210, controller 100 determines whether or not the current combustion start corresponds to the first ignition in response to MOQ ON. Therefore, at the time of the first ignition at the start of the operation of the combustion burner 7, step S210 is determined as YES regardless of which of the on-off combustion control and the proportional combustion control is applied.

  In addition, when the combustion burner 7 is operating, when the transition from the combustion stop period of the on-off combustion control to the combustion period is performed, or when switching to the proportional combustion control is instructed during the combustion stop period of the on-off combustion control, The start of combustion is instructed, and step S160 is YES. However, at the time of ignition for starting combustion, step S210 is NO. That is, step S210 is determined as YES only when the operation of the combustion burner 7 is started, and step S210 is determined as NO in the second and subsequent ignitions until the operation of the combustion burner 7 is ended.

  For example, in the example of FIGS. 4 and 5, step S210 is determined as YES at time t0, while step S210 is determined as NO at times t2 and t4.

  At the time of the second and subsequent ignition (when NO is determined in S210), the controller 100 proceeds to step S220 and sets the ignition pattern according to FIG. As described above, according to the ignition pattern of FIG. 6, initial combustion numbers Ga and Gb suitable for reliable ignition are set (Ga = G0, Gb = G1).

On the other hand, at the time of the first ignition (when YES is determined in S210), the controller 100 proceeds to step S2 30 and sets the ignition pattern according to FIG.

  Referring to FIG. 9, at the time of the first ignition, the second initial combustion number Gb after the flame detection is increased as compared with the ignition pattern of FIG. 6 indicated by a dotted line in the drawing. In the example of FIG. 9, Gb = G1 is set for the second and subsequent ignitions, whereas Gb = G2 (G2> G1) is set for the first ignition. Thus, after the flame detection, an excessive fuel amount is supplied from the injection nozzle 70 with respect to the fuel amount originally required for ignition (Gb = G1). Thereby, it is possible to generate an excessive amount of heat for quickly raising the temperature of the burner cone 80.

On the other hand, even at the time of the first ignition, it is preferable that the first initial combustion number Ga until the ignition is set to Ga = G 0 similarly to the ignition pattern of FIG. This is because, even at the first ignition, until the flame is detected, an optimal amount of fuel is set in consideration of ignitability.

  As described above, by selectively using the ignition patterns of FIGS. 6 and 9, when on-off combustion control is applied, compared to the time of reignition from the combustion stop period at the time of initial ignition by MOQ on, The amount of combustion in the ignition pattern can be increased.

  Thereby, the temperature of the burner cone 80 can be raised early at the time of the first ignition. As a result, even if fuel sprayed from the injection nozzle 70 adheres, odor due to generation of unburned HC can be prevented. In the on / off control in which the combustion period and the combustion operation period are automatically provided alternately, ignition by the ignition pattern is repeatedly executed. For this reason, if the ignition pattern shown in FIG. 9 is always used, combustion by the combustion burner 7 is caused by excessive combustion heat from the combustion burner 7 and excessive rise in hot water temperature at the outlet of the heat exchanger 12. If prohibited, there is a concern that problems may occur in the control of the tapping temperature Th.

  Therefore, during on-off combustion control, during the second and subsequent ignition when the temperature of the burner cone 80 has already risen, the amount of heat for raising the burner cone 80 is excluded, and the amount of combustion is suppressed compared to the time of the first ignition. Combustion at the start of combustion is controlled according to the ignition pattern (FIG. 6). Thereby, it can prevent that the combustion heat by the combustion burner 7 at the time of a combustion start becomes excess.

  In addition, even when proportional combustion control is applied, the generation of unburned HC can be suppressed by increasing the amount of combustion in the ignition pattern at the time of initial ignition. Further, when the combustion is started from the combustion stop period of the on / off combustion control in accordance with the switching from the on / off combustion control to the proportional combustion control, the combustion is performed according to the ignition pattern shown in FIG. Combustion at the start is controlled. Thereby, it can prevent that the combustion heat by the combustion burner 7 at the time of a combustion start becomes excess.

  As described above, in hot water supply apparatus 10 including the heat source device according to the first embodiment, unburned HC is generated due to fuel adhering to burner cone 80 at the time of initial ignition even when on-off combustion control in which ignition frequency is increased is applied. Combustion control at the start of combustion can be appropriately performed so as to achieve both suppression of combustion and prevention of excessive combustion heat generation at the second and subsequent ignitions. Similarly, when applying proportional combustion control, combustion at the start of combustion can be appropriately controlled.

[Embodiment 2]
In the first embodiment, the control for changing the ignition pattern at the start of combustion between the first ignition and the second and subsequent ignitions has been described. However, even when the ignition is performed for the first time, if the temperature of the burner cone 80 is not lowered, such as when the elapsed time from the stop of the operation of the combustion burner 7 is short, unburned HC is generated even if fuel is attached. do not do. Therefore, in the second embodiment, the combustion control of the combustion burner 7 reflecting the burner cone temperature estimation will be described.

  FIG. 10 is a block diagram for explaining the combustion control of the combustion burner according to the second embodiment.

Comparing FIG. 10 with FIG. 3, in the second embodiment, the combustion control unit 120 configured by the controller 100 further includes a temperature estimation unit 155 for estimating the temperature of the burner cone 80. The temperature estimation unit 155 generates a count value CNT (t) for estimating the temperature of the burner cone 80. The count value CNT (t) is increased or decreased by the temperature estimation unit 155 so as to be a value corresponding to the estimated temperature of the burner cone 80. The count value CNT (t) is given to the ignition control unit 150. Since the configuration of other parts in FIG. 10 is the same as that of the first embodiment (FIG. 3), detailed description will not be repeated.

  In the combustion control according to the second embodiment, the process in step S200 of the flowchart shown in FIG. 7, that is, the control process according to the flowchart shown in FIG. 11 is performed as a function of the ignition control unit 150 instead of the flowchart in FIG. Executed.

  FIG. 11 is a flowchart for illustrating a processing sequence of ignition control in the combustion control according to the second embodiment.

  With reference to FIG. 11 and FIG. 8, in the ignition control according to the second embodiment, at the start of combustion by the first ignition (at the time of YES determination in S210), controller 100 counts by temperature estimation unit 155 in step S250. CNT (t) is compared with determination value CNt.

  12 and 13 are diagrams illustrating examples of changes in the count value CNT (t) that is increased or decreased by the temperature estimation unit 155. FIG.

Referring to FIG. 12, count value CNT (t) is set to a predetermined value C0 (CNT (t) = C0) when combustion of combustion burner 7 is stopped (time tx). That is, when combustion is stopped by deactivation of the combustion burner 7, and, in each of the end of the combustion period (at the beginning of the combustion stop period) in on-off combustion control is set to CNT (t) = C 0.

  The count value CNT (t) is decreased at a constant rate while the combustion of the combustion burner 7 is stopped. As a result, the count value CNT (t) at time ty at which combustion starts again becomes smaller as the period during which combustion is stopped (the elapsed time from time tx to ty) becomes longer. Therefore, when the count value CNT (t) at the time ty is lower than the determination value CNt, it can be determined that the burner cone 80 is at a low temperature.

  Alternatively, as shown in FIG. 13, the count value CNT (t) can be increased during combustion in the combustion burner 7.

  Referring to FIG. 13, the behavior of count value CNT (t) at times tx to ty when combustion is stopped is the same as that in FIG. 12, while combustion in combustion burner 7 (until time tx and After time ty), the count value CNT (t) is increased in consideration of the heating of the burner cone 80 by the combustion heat. At this time, it is preferable to adjust the increase in the count value CNT (t) in consideration of temperature saturation or the like based on the heat capacity in the burner cone 80.

  Thus, the temperature estimation unit 155 can estimate the temperature of the burner cone 80 based on the history of combustion by the combustion burner 7 without providing a temperature sensor in the burner cone 80. That is, in step S250, it is equivalently determined whether or not the estimated temperature of burner cone 80 by temperature estimating unit 155 is lower than a predetermined determination temperature.

Referring to FIG. 11 again, when count value CNT (t) is lower than determination value CNt (when YES is determined in S250), controller 100 determines that burner cone 80 is at a low temperature, and step S230. Proceed with the process. Thereby, the ignition pattern according to FIG. 9 is selected. As a result, the burner cone 80 can be heated at an early stage by supplying an excessive amount of fuel with respect to the amount of fuel originally required for ignition (Gb = G1).

  On the other hand, when the count value CNT (t) is greater than or equal to the determination value CNt (when NO is determined in S250), the controller 100 determines that the burner cone 80 is not at a low temperature, and proceeds to step S220. Thus, combustion at the start of combustion is controlled according to an ignition pattern (FIG. 6) in which the amount of heat for raising the burner cone 80 is excluded and the amount of combustion is suppressed compared to the time of initial ignition. Thereby, the ignition pattern according to FIG. 9 for heating the burner cone 80 is selected only when the burner cone is cold.

  Therefore, according to the combustion control according to the second embodiment, it is possible to prevent an excessive amount of fuel from being supplied when the burner cone 80 is not cold, even at the time of initial ignition. Therefore, in addition to the effect of the first embodiment, the generation of excessive combustion heat can be more reliably prevented, and thus combustion at the start of combustion can be controlled more appropriately.

[Embodiment 3]
In the first and second embodiments, the preferred ignition pattern at the start of combustion has been described. In the third embodiment, control of the blower fan at the end of combustion will be described.

  The amount of air supplied from the blower fan 8 shown in FIG. 1 to the combustion mechanism 7 increases or decreases according to the rotational speed of the blower fan 8 (hereinafter also simply referred to as “fan rotational speed”). Therefore, the blower fan is maintained such that the ratio (air-fuel ratio) between the amount of fuel sprayed from the injection nozzle 70 and the amount of air (combustion air) from the blower fan 8 is maintained at an appropriate value (for example, the theoretical air-fuel ratio). The number of revolutions of 8 needs to be controlled.

  FIG. 14 is a functional block diagram illustrating a configuration for fan rotation speed control according to the third embodiment.

  Referring to FIG. 14, fan rotation number control unit 170 includes a fan rotation number setting unit 180 and a fan motor control unit 190. The fan speed setting unit 180 sets the target speed Nf # of the blower fan 8 in accordance with the combustion number Gs in the combustion burner 7 during the combustion operation. The rotation speed sensor 91 detects the fan rotation speed Nf of the blower fan 8. The fan motor control unit 190 controls the supply voltage Vs to the fan motor 9 for rotationally driving the blower fan 8 so that the detected fan rotation speed Nf matches the target rotation speed Nf #.

  For example, when the fan motor 9 is constituted by a DC motor, the supply voltage Vs is a level variable DC voltage or a duty variable pulse voltage. Supply voltage Vs is set by feedforward control based on target rotational speed Nf # and / or feedback control based on a deviation between fan rotational speed Nf and target rotational speed Nf #.

  By controlling the rotation speed of the fan so that the amount of combustion air supplied from the blower fan 8 becomes an appropriate air-fuel ratio, the combustion state in the combustion burner 7 is well maintained.

  Furthermore, the fan rotation speed setting unit 180 controls the fan rotation speed according to a predetermined pattern at the start of combustion and at the time of combustion stop.

  FIG. 15 is a conceptual waveform diagram for explaining a comparative example of fan rotation speed control at the start and end of combustion.

  Referring to FIG. 15, in response to an instruction to start combustion at time ts, fuel injection from injection nozzle 70 is performed from time t0 according to the combustion number Gs generated according to the ignition pattern shown in FIG. 6 or FIG. Is started.

  As described in FIGS. 6 and 9, after the fuel injection is started from time t0, when the combustion number Gs = Ga (first initial combustion number), the sprayed fuel is ignited by the ignition transformer 78, and the flame When a flame is detected by a detection sensor (not shown) (time ta), the combustion number Gs changes up to the second initial combustion number Gb. As described in the first and second embodiments, the first initial combustion number Ga until ignition is set to a common value between the start of combustion corresponding to MOQ on and the start of combustion in the on / off control. On the other hand, the second initial combustion number Gb after ignition is set to a different value. Then, the ignition pattern ends at time tc. In the subsequent time zone surrounded by diagonal lines, the combustion number Gs is controlled according to the required number Rg by on-off combustion control or proportional combustion control.

  Then, at the time te, the combustion is stopped in response to the MOQ being turned off by a curan closing operation or the like (that is, the hot water supply is stopped). Thereby, the fuel injection by the combustion burner 7 is stopped, so that the combustion number Gs = 0.

  When the combustion is stopped, a post-purge operation for continuing the operation of the blower fan 8 is executed until a predetermined time Tpp elapses from the combustion stop (time te). Hereinafter, the duration Tpp of the post purge operation is also referred to as a post purge time Tpp.

  FIG. 15 shows an operation when the MOQ is turned on again by reopening the currant and the hot water is resumed at time tr before the post-purge time Tpp elapses from the combustion stop (time te). In accordance with the re-on of MOQ, the combustion number Gs = Ga is set from time t0 # according to the ignition pattern.

  In the comparative example, the rotation speed of the blower fan 8 is controlled as shown in FIG. 15 in accordance with the combustion start, combustion stop, and combustion restart.

  At the start of combustion, the target rotational speed Nf # of the blower fan 8 is an appropriate value corresponding to the ignition pattern at time tf prior to time t0 at which fuel injection is started in response to an instruction to start combustion at time ts. (Nf # = N1). The number of revolutions N1 in the ignition pattern is adjusted in advance to a value that allows stable ignition in the ignition patterns at times ta to tc.

  When the ignition pattern is terminated at time tc, the target rotational speed Nf # is set to the combustion number Gs according to the on-off combustion control or the proportional combustion control between the times tc and te (the time period surrounded by the oblique lines). Accordingly, an appropriate air-fuel ratio is set to be maintained.

  In the fan rotational speed control according to the comparative example, the target rotational speed Nf # of the blower fan 8 is set to an appropriate value N1 corresponding to the ignition pattern (Nf #) in the post-purge period (time te to tp) after the combustion is stopped. = N1). Note that if the post-purge time Tpp elapses after the combustion is stopped without detecting the MOQ ON, the blower fan 8 is stopped (Nf # = 0).

  In the post-purge period, the operation of the blower fan 8 is maintained in order to remove unburned components during combustion by blowing. The operation time of the blower fan 8 necessary for removing unburned components is about several seconds, but the actual post-purge time Tpp is longer than this, for example, around 5 minutes.

  According to the comparative example, by maintaining the target rotational speed Nf # = N1 of the blower fan 8 throughout the post-purge period, the MOQ is quickly turned on (time tr) due to re-watering after the MOQ is turned off. Combustion by the combustion burner 7 can be resumed. On the other hand, if the blower fan 8 is stopped early after the combustion is stopped, combustion cannot be started until the rotational speed of the blower fan 8 is raised from 0 to N1, so the time required from the re-on of MOQ to the start of combustion. Will increase. For this reason, there is a concern that the temperature of the hot water decreases after the hot water is resumed.

  On the other hand, in the fan rotation speed control according to the comparative example, the fan rotation speed is maintained at the rotation speed N1 suitable for the ignition pattern within the post-purge period. As the temperature of the heat exchanger 12) decreases, there is a concern that the thermal efficiency after restarting the hot water decreases.

  FIG. 16 shows a conceptual waveform diagram for describing fan rotation speed control according to the third embodiment at the time of combustion stop in accordance with MOQ off.

  Referring to FIG. 16, in the heat source apparatus according to the third embodiment, in the post-purge period, target rotation speed Nf # of blower fan 8 is a period in which rotation speed N1 suitable for the ignition pattern is set to a lower rotation speed N2. Is provided. For example, Nf # = N2 (N2 <N1) is set from the start of the post-purge period (time te) to the time tr when the MOQ is turned on again.

  Then, target rotation speed Nf # is increased from time tr toward N1. Then, fuel injection by the combustion burner 7 is resumed according to the ignition pattern from time t0 # after returning to the actual fan speed Nf = N1.

  As a result, according to the third embodiment, there is a period during which the fan rotation speed Nf is lower than that of the comparative example during the post-purge period. The temperature drop of 12) can be suppressed. Regarding the rotational speed N2 in the post-purge period, the time required for returning to the rotational speed N1 corresponding to the ignition pattern and the effect of suppressing the temperature decrease in the combustion can body 6 have a trade-off relationship. It is preferable to find an appropriate value that can balance the two in advance by actual machine experiments or the like.

  Thereby, in the post-purge period at the time of the combustion stop corresponding to MOQ off, the thermal efficiency in the heat source unit can be improved while suppressing the temperature drop at the time of resuming the hot water.

  The fan rotation speed control similar to the post-purge period can be executed even when the combustion is automatically stopped in the on / off combustion control.

  FIG. 17 shows fan rotation speed control according to a comparative example when combustion is stopped in on / off combustion control, and FIG. 18 shows fan rotation speed control according to the third embodiment when combustion is stopped in on / off combustion control. It is.

Referring to FIG. 17, in the on / off combustion control, fuel injection is stopped (Gs = 0) with the end of the combustion period (Gs = G on ) at time t1 or t3 (FIG. 5). As described above, in the on / off combustion control, the ratio between the combustion period length Ton and the combustion stop period length Toff is controlled according to the combustion number Gs. The target rotational speed Nf # of the blower fan during the combustion period is set to the rotational speed Non for maintaining an appropriate air-fuel ratio with respect to the combustion number Gon during the combustion period.

  In the comparative example, similarly to the case of FIG. 15, the target rotational speed Nf # of the blower fan 8 during the combustion stop period is maintained at the rotational speed N1 suitable for the ignition pattern. This is to prepare for a quick restart of combustion when the combustion period is restarted.

  However, when the combustion stop period length Toff is relatively long, there is a concern that the thermal efficiency after resuming the hot water decreases due to the temperature drop in the combustion can body 6 by maintaining the fan rotation speed at N1.

Referring to FIG. 18, according to the third embodiment, target rotation speed Nf # of blower fan 8 is higher than rotation speed N1 suitable for the ignition pattern during part of the combustion stop period (time t1 to t2). A low rotation speed N2 is set. For example, Nf # = N2 can be set at the start of the combustion stop period.

  On the other hand, at the time t2 or t4 when the combustion period is resumed, the actual fan rotation speed Nf needs to return to the rotation speed N1 suitable for the ignition pattern. Therefore, in consideration of the time required for the fan rotation speed Nf to return from N2 to N1, Nf # = N2 can be set at times t1 to t10 in the first half of the combustion stop period.

Then, by increasing the target rotational speed Nf♯ of the blower fan 8 from N2 from the time t10, the time t11, the a Nf♯ = N 1. Thereby, at the time t2 or t4, the actual fan rotation speed Nf is returned to the rotation speed N1 suitable for the ignition pattern. As a result, when the fuel period is restarted, combustion according to the ignition pattern can be restarted promptly.

  In the on-off combustion control, the combustion stop period length Toff is preset according to the combustion number Gs. Therefore, in consideration of the time required to return the fan rotation speed from N2 to N1, according to the combustion stop period length Toff so that the time when Nf # = N2 (rotation speed reduction time Tcnt) can be secured as long as possible. The time t10 can be determined.

  Thereby, the temperature drop in the combustion can 6 during the combustion stop period can be reduced more than that in the comparative example (maintained at Nf # = N1) without changing the combustion stop period length Toff. Thereby, the thermal efficiency in the heat source unit can be improved without affecting the control of the hot water temperature Th by the on / off combustion control.

  In the on / off combustion control, when the ratio Kt of the equation (3) is controlled by adjusting the combustion stop period length Toff, the rotation speed N2 in the first half of the combustion stop period is made variable according to the combustion stop period length Toff. It is also possible to control.

  Here, the time required to return the fan rotational speed from N2 to N1 can be calculated backward based on the rotational speed difference (N1-N2). Therefore, according to the combustion stop period length Toff, a set of the fan rotation speed N2 and the rotation speed reduction time Tcnt that can return the fan rotation speed Nf to N1 by the end of the combustion stop period can be determined. . Also for such a set of the fan rotation speed N2 and the rotation speed decrease time Tcnt, it is possible to find in advance an appropriate value according to the combustion stop period length Toff by an actual machine experiment or the like.

  As described above, according to the heat source apparatus according to the third embodiment, from the stop of the combustion operation to the restart of the combustion operation, specifically, the post-purge period by the combustion stop corresponding to the MOQ off and the on-off combustion It is possible to provide a period in which the rotational speed of the blower fan 8 is lower than the rotational speed N1 corresponding to the ignition pattern in both of the combustion stop periods due to the automatic combustion stop in the control. Thereby, thermal efficiency can be improved by the temperature fall reduction in the combustion can body 6 in the said period.

  Next, referring to FIGS. 19 and 20, control processing for fan speed control at the time of combustion stop in the heat source unit according to the third embodiment will be described. The processing shown in FIGS. 19 and 20 is periodically executed by the controller 100.

  Referring to FIG. 19, controller 100 determines whether or not a combustion stop is instructed in step S <b> 100. As described above, the combustion stop instruction includes a combustion stop corresponding to a hot water supply stop (MOQ off) by a curan closing operation or the like, and an automatic combustion stop in the on-off combustion control. When combustion stop is not instructed (NO in step S100), the following processing is not executed.

  When the combustion stop is instructed (YES in S100), the controller 100 determines in step S110 whether the combustion is stopped due to the MOQ being turned off. When the combustion is stopped due to MOQ off (when YES is determined in S110), the controller 100 advances the process to step S120 in order to realize the fan rotation speed control shown in FIG.

  In step S120, the controller 100 initializes a timer T for measuring the elapsed time from the stop of combustion (T = 0), and in step S130, sets the target rotational speed Nf # of the blower fan 8 to the ignition pattern. N2 is set lower than the corresponding rotation speed N1. Furthermore, the controller 100 counts up the timer T in step S140.

  If the combustion is turned on in response to the MOQ being turned on again by a curan opening operation or the like while the timer T is counting, the controller 100 advances the process to step S160 by an interruption process based on a YES determination in step S150. . In step S160, target rotational speed Nf # is increased to rotational speed N1 corresponding to the ignition pattern. As a result, when the actual fan speed Nf increases to N1, fuel injection according to the ignition pattern is resumed.

  When combustion is not restarted (NO in step S150), controller 100 determines in step S170 whether or not the time measured by timer T has reached post-purge time Tpp. Until the post-purge time Tpp elapses after the combustion is stopped (NO in S170), the target rotation speed Nf # of the blower fan 8 is maintained at N2 by repeating the processes of steps S130 to S150.

  When the time measured by the timer T reaches the post-purge time Tpp (when YES is determined in S170), the controller 100 proceeds to step S180 and stops the blower fan 8.

  By the process of steps S120 to S180, the fan rotational speed Nf is reduced from the rotational speed N1 with respect to the ignition pattern until the post purge time Tpp elapses after the combustion stop corresponding to the MOQ off (the rotational speed N2). ), The post-purge by the blower fan 8 is executed. Further, when the combustion is resumed, the combustion can be smoothly resumed by resuming the fuel injection after the fan rotational speed Nf returns to N1.

  On the other hand, when the combustion is not stopped by the MOQ off, that is, when the automatic combustion is stopped by the on / off combustion control (when NO is determined in S110), the controller 100 rotates the fan shown in FIG. In order to realize the number control, the process proceeds to step S200 in FIG.

  Referring to FIG. 20, controller 100 initializes timer T for measuring the elapsed time from the stop of combustion in step S200, as in step S120 (T = 0). Further, in step S210, the controller 100 reduces the rotational speed during the combustion stop period in consideration of the time required for returning from the fan speed N2 to N1 based on the combustion stop period length Toff of the on / off combustion control. Set time Tcnt.

  As described above, the fan rotation speed N2 (N2 <N1) may be a fixed value or a variable value corresponding to the combustion stop period length Toff. When the fan rotation speed N2 is a variable value, both the fan rotation speed N2 and the rotation speed decrease time Tcnt are set in step S210. By setting the fan rotation speed N2 to a variable value, it is possible to further reduce the temperature drop in the combustion can body 6.

  The controller 100 counts up the timer T in step S230. Further, in step 240, controller 100 determines whether or not the time measured by timer T has reached rotation speed reduction time Tcnt. Until the rotation speed reduction time Tcnt elapses after the combustion is stopped (NO in S240), the target rotation speed Nf # of the blower fan 8 is maintained at N2 by repeating the processes of steps S220 and S230.

  When the time counted by the timer T reaches the rotation speed reduction time Tcnt (YES in S240), the controller 100 proceeds to step S250 to set the target rotation speed Nf # of the blower fan 8 to the rotation speed corresponding to the ignition pattern. Raise to N1. As a result, the actual fan speed Nf can be increased to N1 by the end of the combustion stop period (that is, the start of the next combustion time), so that the on / off combustion control for controlling the hot water temperature Th is followed. The combustion stop period length Toff does not change even if the fan speed is temporarily reduced.

  Thus, according to the heat source device according to the third embodiment, the next combustion start is performed both in the post-purge period due to the combustion stop according to the MOQ off and in the combustion stop period due to the automatic combustion stop in the on-off combustion control. The thermal efficiency can be improved by reducing the temperature drop in the combustion can 6 without significantly affecting the temperature.

  In the third embodiment, the rotational speed N1 corresponds to the “first rotational speed”, and the rotational speed N2 corresponds to the “second rotational speed”. Further, as shown in FIG. 16 and FIG. 18, a period (first period) in which the blower fan 8 operates at the rotational speed N1 after a period (second period) in which the blower fan 8 operates at the rotational speed N2. ) Is provided. Further, the rotation speed reduction time Tcnt corresponds to the “first time”.

  In the present embodiment, a hot water supply apparatus having a combustion burner that sprays petroleum (kerosene) as liquid fuel has been described as a representative example, but the application of the present invention is not limited to such a configuration example. That is, the combustion control at the start of combustion (at the time of ignition) according to the present invention can be commonly applied to a heat source device having a combustion mechanism for spraying liquid fuel.

  6 Combustion can body, 7 Combustion burner (combustion mechanism), 8 Blower fan, 10 Hot water supply device, 11 Water inlet pipe, 12 Heat exchanger, 16 Hot water outlet pipe, 17, 19 Temperature sensor, 18 Flow rate sensor, 30 Smoke stack, 70 Injection Nozzle, 71 Electromagnetic on-off valve, 72 Electromagnetic supply pump, 73 Fuel supply pipe, 74 Return pipe, 75 Oil temperature detection sensor, 76 Flow control valve, 77 Check valve, 78 Ignition transformer, 80 Burner cone, 100 Controller, 110 Number calculation unit, 120 combustion control unit, 130 on-off combustion control unit, 140 proportional combustion control unit, 150 ignition control unit, 155 temperature estimation unit, 160 control mode selection unit, 170 fan rotation number control unit, 180 fan rotation number setting unit 190 Fan motor controller, CNT (t) count value, CNt judgment value, Ga, Gb initial combustion Number, Gs Combustion Number, Nf Fan Speed, Nf # Target Speed (Blower Fan), Q Flow Rate, Rg Required Number, So, Sp, Sv Control Command (Combustion Burner), Tc Predetermined Period, Tcnt Rotation Number drop time, Th tapping temperature, Toff combustion stop period length, Ton combustion period length, Tpp post purge time, Tr set temperature, Tw incoming water temperature.

Claims (9)

A combustion mechanism that generates combustion heat by burning the sprayed liquid fuel;
A control device for controlling the combustion mechanism,
The control device includes:
A calculation unit for calculating the required combustion amount;
The adjustment of the ratio between the combustion period and the combustion stop period by on-off control that automatically and alternately provides a combustion period at a constant combustion amount by the combustion mechanism and a combustion stop period of the combustion mechanism according to the required combustion amount A first controller for controlling combustion heat;
An ignition control unit for controlling a combustion amount in the combustion mechanism according to a predetermined ignition pattern when starting a combustion operation of the combustion mechanism,
In the case where the combustion operation is started in response to detection of the minimum operation flow rate, the ignition control unit starts the combustion operation from the combustion stop state by the on / off control when the combustion amount in the ignition pattern is started in response to detection of the minimum operation flow rate. Configured to increase more than
The ignition pattern is defined by a first initial combustion amount supplied before ignition and a second initial combustion amount supplied for a predetermined time after ignition confirmation,
The ignition control unit increases or decreases the amount of combustion in the ignition pattern by adjusting the second initial combustion amount . The control device includes:
A second control unit for controlling the combustion heat in accordance with the required combustion amount by proportional combustion control for adjusting a combustion amount in the combustion period provided continuously;
When the required combustion amount is smaller than a predetermined value, the on / off control by the first control unit is selected, and when the required combustion amount is larger than the predetermined value, the second control unit performs the A control mode selection unit for selecting proportional combustion control,
When the proportional combustion control is selected when the combustion operation is started in response to the detection of the minimum operating flow rate, the ignition control unit starts the combustion operation from the combustion stop state of the on / off control. The heat source machine according to claim 1, wherein the amount of combustion in the ignition pattern is increased as compared with a case where the ignition pattern is started. The combustion mechanism is
An injection nozzle for spraying the liquid fuel;
A burner cone disposed around the spray port of the liquid fuel by the injection nozzle,
The control device includes:
A temperature estimation unit for estimating a temperature of the burner cone when the combustion operation is started;
When the estimated temperature of the burner cone is higher than a predetermined temperature, the ignition control unit is at the start of the combustion operation in response to the detection of the minimum operating flow rate compared to when the temperature is lower than the predetermined temperature. The heat source machine according to claim 1, wherein the heat source machine is configured to reduce a combustion amount in the ignition pattern.   The heat source unit according to claim 3, wherein the temperature estimation unit estimates the temperature of the burner cone based on an elapsed time since the combustion mechanism stopped the previous combustion operation.   The heat source apparatus according to claim 3, wherein the temperature estimation unit estimates the temperature of the burner cone based on combustion and combustion stop history in the combustion mechanism. A blower fan configured to supply an air amount corresponding to the rotational speed to the combustion mechanism;
The control device includes:
A fan rotation speed control unit for controlling the rotation speed of the blower fan in correspondence with the amount of fuel sprayed in the combustion mechanism;
The fan rotation speed control unit includes a first period in which the blower fan rotates at a first rotation speed corresponding to the ignition pattern between the stop of the combustion operation and the restart of the combustion operation. Controlling the rotational speed of the blower fan to provide a second period during which the blower fan rotates at a second rotational speed lower than the first rotational speed,
The heat source machine according to claim 1 or 2, wherein the first period is provided after the second period. When the combustion operation is stopped in response to the non-detection of the minimum operating flow rate, the fan rotation speed control unit adjusts the rotation speed of the blower fan until a predetermined post purge time elapses after the combustion operation is stopped. When the minimum operating flow rate is detected again before the post purge time elapses while controlling the second rotational speed, the rotational speed of the blower fan is increased to the first rotational speed,
When the minimum operating flow rate is detected again before the post-purge time elapses, the ignition control unit controls the rotation speed of the blower fan at the first rotation speed by the fan rotation speed control unit. The heat source apparatus according to claim 6 , wherein fuel combustion in the combustion mechanism is started after reaching the state. When the on-off control is selected and the combustion operation is stopped in response to the end of the combustion period, the fan rotation speed control unit is configured to start the combustion stop period until a first time elapses. The rotational speed of the blower fan is controlled to the second rotational speed, and the rotational speed of the blower fan is increased to the first rotational speed before the end of the combustion stop period after the first time has elapsed. The heat source machine according to claim 6 . The fan rotation speed control unit variably controls the second rotation speed and the first time according to a length of the combustion stop period adjusted according to the required combustion amount in the on / off control. Item 9. The heat source machine according to Item 8 .

Images