Combustion device and hot water device equipped with the same

Abstract

A combustion device capable of appropriately improving ignition performance is provided. [Solution] A combustion device C includes a fan 1, a premixing device A capable of generating a mixture of air and fuel gas by driving the fan 1, and an ignition device 22 capable of igniting the mixture in a combustion chamber 29, wherein the premixing device A is equipped with a flapper 5 that can open and close a portion of the gas flow path 3 and that opens to a greater extent when the fan 1 is driven at a high speed than when it is driven at a low speed. In principle, the ignition of the mixture by the ignition device 22 is a standard ignition operation performed in a first driving speed range SR1 of the fan 1 in which the flapper 5 is in an open state, and if the mixture does not ignite through this standard ignition operation, then, as an exception, it is a non-standard ignition operation performed in a second driving speed range SR2 of the fan 1 in which the flapper 5 is in a closed state.

Description

[Technical Field]

[0001] The present invention relates to a combustion apparatus of the all-primary air combustion type that mixes combustion air and fuel gas and burns the mixture, and to a hot water apparatus such as a hot water supply or hot water heating apparatus that is equipped with the same. [Background technology]

[0002] A specific example of a combustion device is described in Patent Document 1. The combustion device described in this document is an all-primary air combustion type used as a component of a water heating system, and includes a variable speed fan, a premixing device, a combustion chamber equipped with a burner unit, and an ignition device. The premixing device includes a gas flow path through which air flows when driven by the fan, and a fuel gas outlet that discharges fuel gas into the gas flow path by the negative pressure generated when air flows through the gas flow path, and is capable of generating a mixture of the air and the fuel gas. This mixture is supplied to the combustion chamber and combusted.

[0003] However, the gas flow path of the premixer is divided into first and second flow paths, and the first of these can be opened and closed by a flapper. The opening degree of the flapper changes according to the driving speed of the fan (air flow rate in the first flow path), and is larger when the driving speed of the fan is high than when it is low.

[0004] With this configuration, even when the fan driving speed is low and the air flow rate through the gas flow path of the premixer is low, the flapper closes the first flow path, increasing the air flow rate in the second flow path and strengthening the negative pressure in the second flow path. As a result, even when the fan driving speed is low, an appropriate amount of fuel gas can be discharged into the second flow path. This action is effective in increasing the turndown ratio.

[0005] However, the above-mentioned prior art still has room for improvement, as will be described below.

[0006] That is, the combustion device described above, like other general combustion devices, is required to have good ignition performance. However, Patent Document 1 does not disclose any means for meeting such a requirement, and it is difficult to accurately meet the requirement. As fuel gas for combustion devices, there is an emergency gas, for example, a mixture of LP gas and air at about 50% each, and there are cases where it is desired to use this emergency gas as fuel gas. In such cases, improved ignition performance is even more strongly required.

[0007] Meanwhile, one example of a means for improving the ignition performance of a combustion device is described in Patent Document 2. In this means, if an initial ignition operation is performed to start the combustion operation of the combustion device but fails to ignite, the fan rotation speed is reduced from that of the initial ignition operation and the ignition operation is performed again. By reducing the fan rotation speed, the mixture becomes fuel-rich, making it easier for the mixture to ignite. However, because the measure in Patent Document 2 merely reduces the fan rotation speed during the re-ignition operation, optimization is not achieved even if it is applied as is to a combustion device equipped with the premixing device described in Patent Document 1. Therefore, it is difficult to obtain sufficiently excellent ignition performance when, for example, the above-mentioned emergency gas is used. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication No. 2021-99204 [Patent Document 2] Japanese Patent Application Laid-Open No. 2003-336836 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention was devised under the circumstances described above, and its objective is to provide a combustion device that can appropriately improve ignition performance compared to conventional technology, and a hot water device equipped with the same. [Means for solving the problem]

[0010] In order to solve the above problems, the present invention provides the following technical solutions.

[0011] A combustion device provided according to a first aspect of the present invention comprises: a premixing device having a variable speed fan, a gas flow path through which air flows when the fan is driven, and a fuel gas outlet communicating with the gas flow path, and capable of generating a mixture of the air and the fuel gas by causing fuel gas to flow from the fuel gas outlet into the gas flow path due to negative pressure generated when the air flows through the gas flow path; a combustion chamber located on the exhaust side of the fan to receive the mixture and for burning the mixture; and an ignition device capable of igniting the mixture in the combustion chamber, is a combustion device that has a flapper that can open and close a part of the gas flow path, and the opening degree of this flapper is larger when the driving speed of the fan is high than when it is low, and is characterized in that the ignition operation of the ignition device to the air-fuel mixture is, in principle, a standard ignition operation that is performed in a first driving speed range of the fan in which the flapper is in an open state, and if the air-fuel mixture is not ignited by this standard ignition operation, then, as an exception, a non-standard ignition operation that is performed in a second driving speed range of the fan in which the flapper is in a closed state.

[0012] This configuration provides the following effects. That is, the ignition operation of the ignition device to ignite the air-fuel mixture is, in principle, a standard ignition operation performed in the first driving speed range of the fan, in which the flapper is in the open state. During this standard ignition operation, a large amount of air flows through the gas flow path of the premixing device, and a large amount of fuel gas is mixed with the air in an amount commensurate with the amount of air, thereby generating a large amount of air-fuel mixture. Therefore, by igniting the air-fuel mixture through this standard ignition operation, it is possible to immediately achieve driving combustion with high combustion power in the combustion chamber. As a result, when the combustion device according to the present invention is used, for example, for heating hot water in a water heater, it has the advantage of being able to quickly heat water to a predetermined hot water temperature. On the other hand, if the standard ignition operation fails to ignite the air-fuel mixture, a non-standard ignition operation is performed as an exceptional ignition operation in the second driving speed range of the fan, in which the flapper is closed. During this non-standard ignition operation, air does not flow through a portion of the gas flow path, and a mixture is generated in which fuel gas is mixed with the small amount of air flowing through the other portion. This makes the mixture fuel-rich, improving the ignition ability of the mixture. This can also be used effectively when emergency gas, for example, a mixture of approximately 50% LP gas and 50% air, is used as the fuel gas. According to the present invention, the difference between standard ignition operation and non-standard ignition operation is whether the flapper of the premixing device is open or closed. Therefore, unlike Patent Document 2, which simply changes the rotation speed of the fan, the standard ignition operation and non-standard ignition operation clearly differ in the air-fuel gas mixture ratio and the overall amount of mixture produced, making it possible to ensure excellent combustion response performance through standard ignition operation and significantly improve ignition performance through non-standard ignition operation.

[0013] In the present invention, preferably, the non-standard ignition operation is performed by the fan being driven by the second driving The speed control is configured to be executed in the fastest speed range.

[0014] This configuration provides the following effects. That is, when the fan is in the second driving speed range, a portion of the gas flow path is closed by the flapper, so a mixture of fuel gas and air is generated only in the remaining portion of the gas flow path. Under such circumstances, when the fan is set to the highest speed within the second driving speed range and the negative pressure in the remaining portion of the gas flow path is strengthened, the amount of fuel gas flowing into that portion increases. This makes the mixture fuel-rich, which is preferable for improving ignition performance during non-standard ignition operation.

[0015] In the present invention, preferably, the first driving speed range includes a specific speed range in which the flapper is in a partially open state, and the standard ignition operation is configured to be performed with the fan driving speed set to the fastest speed range within the specific speed range or a speed range equal to or greater than the fastest speed range.

[0016] With this configuration, the standard ignition operation is performed when the flapper is partially open and the opening is close to full open, or when the flapper is fully open. In other words, the standard ignition operation is not performed when the flapper is only slightly open. Therefore, the standard ignition operation is an ignition operation that can be clearly distinguished from non-standard ignition operations, and this standard ignition operation is more preferable in terms of improving combustion response performance.

[0017] In the present invention, preferably, when an ignition operation of the air-fuel mixture is performed, the standard ignition operation is performed a number of times equal to or less than a predetermined first upper limit number of times until the air-fuel mixture ignites, and if the air-fuel mixture does not ignite even though the standard ignition operation has been performed the first upper limit number of times, the non-standard ignition operation is then performed.

[0018] With this configuration, the procedure for igniting the air-fuel mixture can be made rational.

[0019] In the present invention, preferably, when the standard ignition operation is repeatedly performed a plurality of times, the driving speed of the fan is gradually increased.

[0020] This configuration provides the following effects. In other words, when the standard ignition operation is repeatedly performed multiple times, wind continues to blow into the combustion chamber and its downstream portion from the outside, which can prevent the air-fuel mixture from igniting. In contrast, with the above configuration, the fan driving speed is gradually increased, which is effective in countering the wind blowing. Therefore, this is more preferable in terms of eliminating the difficulty in igniting the air-fuel mixture due to wind blowing.

[0021] In the present invention, preferably, if the non-standard ignition operation has been repeatedly performed a predetermined second upper limit number of times but the air-fuel mixture does not ignite, it is determined that an abnormality has occurred, and the ignition operation is not continued thereafter.

[0022] With this configuration, the safety of the combustion device can be ensured.

[0023] In the present invention, preferably, when the standard ignition operation and / or the non-standard ignition operation is repeatedly performed, an interval period is ensured, and during the interval period, the fan is driven at a speed higher than that during the standard ignition operation and the non-standard ignition operation. The intake manifold is also driven at high speed to perform scavenging of the combustion chamber.

[0024] With this configuration, during intervals when the standard ignition operation and / or the non-standard ignition operation are repeatedly performed multiple times, the scavenging process for the combustion chamber is performed with the fan driving speed set to a higher speed than during the standard ignition operation or the non-standard ignition operation. This scavenging process is preferable in terms of improving ignition performance because it removes unburned gas from the combustion chamber.

[0025] In the present invention, it is preferable that a setting means is provided which can select and set a specific ignition operation mode as the ignition operation for the air-fuel mixture, and when the specific ignition operation mode is set by the setting means, when the ignition operation for the air-fuel mixture is performed, the standard ignition operation is omitted and the non-standard ignition operation is performed.

[0026] This configuration provides the following effects. That is, when it is known in advance that the fuel gas to be used is one that has poor ignition characteristics, such as emergency gas that is a mixture of approximately 50% LP gas and 50% air, the setting means is used to set the specific ignition operation mode. As a result, when the fuel gas is to be ignited, the standard ignition operation is omitted and a non-standard ignition operation that has excellent ignition characteristics is immediately performed, thereby enabling the ignition of the fuel gas to be completed in a short time.

[0027] A hot water apparatus provided by a second aspect of the present invention is a hot water apparatus comprising a combustion device and a heat exchanger capable of heating hot water using combustion gas generated by the combustion device, and is characterized in that the combustion device provided by the first aspect of the present invention is used as the combustion device.

[0028] According to this configuration, the same effects as those described for the combustion device provided by the first aspect of the present invention can be obtained.

[0029] Other features and advantages of the present invention will become more apparent from the following description of the preferred embodiments of the invention, which proceeds with reference to the accompanying drawings. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic explanatory diagram showing an example of a hot water device equipped with a combustion device according to the present invention. [Figure 2] FIG. 2 is a perspective view showing the appearance of a premixing device of the combustion apparatus shown in FIG. [Figure 3] FIG. 3 is an exploded perspective view of FIG. 2. [Figure 4] (a) is a cross-sectional view of the premixing device shown in Figure 2 in a closed state with a flapper, (b) is a cross-sectional view at a position different from (a), and (c) is a cross-sectional view taken along line IVc-IVc of (b). [Figure 5] 3(a) is a cross-sectional view of the premixing device shown in FIG. 2 with a flapper fully open, and FIG. 3(b) is a cross-sectional view at a different position from that in FIG. 2(a). [Figure 6] 3(a) is a plan view of a premixing flow path forming member of the premixing device shown in FIG. 2, (b) is an enlarged view of a main part thereof, and (c) is a plan cross-sectional view of (a). [Figure 7] 2 is a graph showing an example of the relationship between the driving speed of the fan of the combustion device shown in FIG. 1 and the CO2 concentration in the combustion gas. [Figure 8] 2 is a flowchart showing an example of an operation procedure executed in the hot water apparatus equipped with the combustion device shown in FIG. [Figure 9] 2(a) to 2(c) are time charts showing an example of a control mode relating to the ignition device, the fan, and the determination of the presence or absence of an abnormality in the combustion device shown in FIG. [Figure 10] 1. (a) to (c) are time charts showing other examples of control modes relating to the ignition device, the fan, and the determination of the presence or absence of an abnormality in the combustion device shown in FIG. [Figure 11] 10 is a flowchart showing another example of the operation procedure executed in the hot water apparatus equipped with the combustion device shown in FIG. [Figure 12] FIG. 10 is a schematic explanatory diagram showing another example of a hot water device equipped with a combustion device according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0031] Preferred embodiments of the present invention will now be described in detail with reference to the drawings.

[0032] The hot water apparatus WH shown in FIG. 1 is a hot water supply apparatus, and includes a combustion device C, a heat exchanger 11, a hot water supply piping section B, and a control section 5, each of which is arranged in an outer case 19. The combustion device C includes a premixing device A, a variable speed fan 1, a combustion chamber 29 equipped with a burner section 2, a can body 10 that forms the combustion device C inside, an ignition device (spark plug) 22 provided in the combustion chamber 29, and a flame detection sensor (flame rod) 23.

[0033] The premixing device A will be described in detail later. A mixture of air and fuel gas is generated using the premixing device A, and this mixture is supplied to the combustion chamber 29 via the fan 1. The burner unit 2 provided in the combustion chamber 29 includes a perforated plate 21 with a plurality of vent holes 20 (flame holes). The mixture passes through the perforated plate 21 and is ignited by an ignition device 22 below the perforated plate 21 to burn. The combustion gases generated by this combustion act on the heat exchanger 11, heating the hot and cold water passing through the heat exchanger 11. The heat exchanger 11 includes primary and secondary heat exchange sections 11A and 11B for recovering sensible and latent heat, respectively. However, the heat exchanger 11 is not limited to this, and may include only the heat exchange section 11A for recovering sensible heat, for example. Reference numerals 11a and 11b denote the inlet and outlet of the heat exchanger 11 for the hot and cold water, respectively. After passing through the heat exchanger 11, the combustion gas passes through the exhaust duct portion 10a of the can body 10 and is discharged to the outside as exhaust gas from the exhaust port 10b at the end of the duct portion.

[0034] The hot water supply piping section B includes an inlet channel 70 that sends hot water received from the outside at a water inlet 73 to the heat exchanger 11, an outlet channel 71 that directs the hot water discharged from the heat exchanger 11 to an outlet 74, a bypass channel 72, and a flow path switching valve V3. The bypass channel 72 serves to adjust the outlet temperature by directing a portion of the unheated hot water flowing through the inlet channel 70 to a midpoint Pa of the outlet channel 71 where it is mixed with heated hot water. Hot water can be supplied to the desired hot water supply destination from the outlet 74. The inlet channel 70 is provided with a flow rate sensor Sa that determines whether the hot water flow rate of the heat exchanger 11 is equal to or greater than a predetermined minimum operating flow rate (MOQ-ON).

[0035] As clearly shown in FIGS. 2 to 6, the premixing device A includes a device main body A0, a flapper 5 assembled to the device main body A0, and flow path adjusting members 82A and 82B. In the drawing, the x and y directions are directions that intersect with each other and also intersect with the air flow direction (upward) in the gas flow path 3, which will be described later.

[0036] The device main body A0 includes a premixing flow path forming member 4 and a pipe joint 9. The premixing flow path forming member 4 includes a cylindrical portion 49 that forms the venturi-shaped gas flow path 3 therein, an attachment flange portion 48 connected to the upper end of the cylindrical portion 49, a base portion 44, and a fuel gas flow path 8.

[0037] The pipe joint 9 is connected to a gas pipe 99 (see FIG. 1) and receives a supply of fuel gas. The pipe joint 9 includes a cylindrical portion 94 that defines a hollow portion inside, which is the starting end of the fuel gas flow path 8, and an attachment flange 95 that is connected to the base end of the cylindrical portion 94.

[0038] The base portion 44 is the portion to which the pipe coupling portion 9 is attached, and is shaped like a pedestal or similar that is provided integrally with the outer peripheral surface portion of the cylindrical portion 49, and is provided with a flange portion 44a that corresponds to the flange portion 95 of the pipe coupling portion 9. The pipe coupling portion 9 is attached to the base portion 44 by fastening the flange portions 95, 44a together using threaded members 90 such as screws while the flange portions 95, 44a are in opposing contact with each other.

[0039] As shown in FIG. 1 , the premixing device A has a pipe joint 9 connected to a gas pipe 99, and receives a supply of fuel gas from a fuel gas supply source (not shown) via a main valve (on-off valve) V2 and a pressure equalizing valve (zero governor) V1. Meanwhile, the premixing device A is directly or indirectly connected to the intake side of the fan 1 using a flange 48. When the fan 1 is driven, external air flows into the premixing passage-forming member 4 (gas passage 3 within the cylindrical portion 49). The negative pressure generated by this air flow causes fuel gas to flow out from first and second fuel gas outlets 80a and 80b (described later), generating a mixture of the fuel gas and the air. This mixture is supplied to the combustion chamber 29 via the fan 1.

[0040] 4(b) and 5(b), a partition wall 40 extending in the vertical direction along the air flow direction is provided in the gas flow path 3. This divides a part of the gas flow path 3 into first and second flow paths 3a and 3b that are aligned in the y direction with the partition wall 40 in between.

[0041] 4 to 6, first and second blade portions 41a and 41b (shown as dotted portions in FIGS. 6(a) and 6(c)) are provided in the first and second flow paths 3a and 3b. First and second fuel gas outlet ports 80a and 80b are provided on the upper surfaces of the first and second blade portions 41a and 41b facing downstream in the air flow direction, and open upward.

[0042] The first and second blade portions 41a, 41b extend in the y direction so as to horizontally cross the first and second flow paths 3a, 3b, respectively, and one end of each of them is connected to the inner surface of the peripheral wall of the gas flow path 3 (the inner surface of the peripheral wall of the cylindrical portion 49), and the other ends of each of them are connected to each other across the partition wall portion 40. 6, a portion of the first flow path 3a is divided into a pair of regions 3a' that sandwich the first blade portion 41a in the x direction. A portion of the second flow path 3b is divided into a pair of regions 3b' that sandwich the second blade portion 41b in the x direction.

[0043] The fuel gas flow path 8 begins within the cylindrical portion 94 of the pipe joint 9 and terminates at first and second fuel gas outlets 80a, 80b. The fuel gas flow path 8 is configured with flow path adjustment members 82A, 82B. These flow path adjustment members 82A, 82B are attached between the pipe joint 9 and the base 44, and the inner portion of the flow path adjustment member 82A communicates with the upstream portion of the fuel gas flow path 8 via an opening 82c. The flow path adjustment member 82B has two openings 82a, 82b, and the fuel gas flow path 8 branches into the first and second fuel gas flow paths 8a, 8b starting from these openings 82a, 82b. The flow path resistance of each of the first and second fuel gas flow paths 8a, 8b can be individually controlled by adjusting the opening area of ​​the openings 82a, 82b. The first and second fuel gas flow paths 8a, 8b are formed inside the base portion 44 and inside the first and second blade portions 41a, 41b. The fuel gas supplied to the pipe joint portion 9 passes through the first and second openings 82a, 82b of the flow path adjustment member 82B and the first and second fuel gas flow paths 8a, 8b, and is guided to the first and second fuel gas outlets 80a, 80b.

[0044] An air inlet 3c and an air outlet 3d, which communicate with the first and second flow paths 3a and 3b, are formed in the lower and upper parts of the cylindrical portion 49. When the fan 1 is driven, external air flows into the air inlet 3c and then branches off into the first and second flow paths 3a and 3b. Due to the negative pressure generated by the air flow in the first and second flow paths 3a and 3b, fuel gas flows out from the first and second fuel gas outlets 80a and 80b, generating a mixture of air and fuel gas. This mixture flows out of the cylindrical portion 49 (toward the intake port of the fan 1) from the air outlet 3d.

[0045] As shown in FIGS. 4 to 6, the flapper 5 can open and close the first flow path 3a (a pair of regions 3a'), and at the same time, can open and close the first fuel gas outlet 80a. The first flow path 3a corresponds to a part of the gas flow path referred to in the present invention. The flapper 5 is, for example, a resin molded product, and its base end is supported by a support part 52 using a shaft 61, and can swing up and down in the height direction around its center line CL. As clearly shown in FIG. 3, the shaft 61 is supported by a pair of auxiliary members 60 having support holes 60a. The pair of auxiliary members 60 are attached to a step part 43 separately provided in the first flow path 3a using a screw member 92 or the like.

[0046] The flapper 5 swings using its own weight as a downward force and the airflow traveling upward through the first flow path 3a as an upward force, and when the air flow rate through the gas flow path 3 is low, the opening degree is smaller than when the air flow rate is high. When the air flow rate is low, the flapper 5 is in a closed state, lying on its side, due to its own weight, but when the air flow rate increases, it is lifted up by the upward air flow and enters an open state. The open state of the flapper 5 includes not only a fully open state but also a partially open state. A pair of fins 55 are appropriately protruding from the flapper 5 and positioned to sandwich the first blade portion 41a when the flapper 5 is in the closed state.

[0047] The control unit 5 is configured using a microcomputer or the like, and executes operation control and data processing of each unit of the hot water apparatus WH, and also executes drive speed control (rotation control) of the fan 1 when performing hot water supply operation. However, the specific contents thereof will be described later with reference to Figs. 7 to 10 etc. A remote control 5A installed in the kitchen or bathroom is communicatively connected to the control unit 5. This remote control 5A is equipped with a display unit 50 capable of displaying various data, a plurality of operation switches 51, and a sound generator (not shown). Using this remote control 5A, it is possible to set the target hot water temperature and a "specific ignition operation mode" (described later), and to notify errors using audio or image displays.

[0048] FIG. 7 shows an example of the relationship between the driving speed of the fan 1 of the combustion device C of this embodiment and the CO2 concentration in the combustion gas. As shown in the figure, the drive speed range of the fan 1 on the horizontal axis is divided into a second drive speed range SR2 in which the flapper 5 of the premixer A is in a closed state (fully closed state), and a first drive speed range SR1 which is faster than the second drive speed range SR2 and in which the flapper 5 is in an open state. The lower speed range of the first drive speed range SR1 is a specific speed range SR1a in which the flapper 5 is in a partially open state, and an even faster range SR1b is a speed range in which the flapper 5 is in a fully open state. On the other hand, the CO2 concentration in the combustion gas on the vertical axis corresponds to the ease of combustion of the mixture, and it can be determined that the higher this concentration, the better the ignition ability.

[0049] As shown by line L in Figure 7, in the process of gradually increasing the drive speed of the fan 1 from the low-speed range, in the second drive speed range SR2, the higher the drive speed, the higher the CO2 concentration. This is because if the drive speed of the fan 1 is too slow, the negative pressure generated in the gas flow path 3 is weak and the outflow of fuel gas into the gas flow path 3 is not promoted, whereas if the drive speed is increased, this problem is resolved and the outflow of fuel gas is promoted. The CO2 concentration is shown in Figure 7 The peak occurs at the point indicated by the symbol Na, that is, at the boundary speed between the second drive speed range SR2 and the first drive speed range SR1 (the speed immediately before the flapper 5 changes from the closed state to the open state). When the driving speed of the fan 1 shifts from the second driving speed range SR2 to a specific speed range SR1a of the first driving speed range SR1, the CO2 concentration gradually decreases as the driving speed of the fan 1 increases, and the CO2 concentration stabilizes in the intermediate range of the specific speed range SR1a and in higher speed ranges.

[0050] Next, an example of operational control in the water heating device WH equipped with the combustion device C described above and its action will be described with reference to the flowchart of FIG.

[0051] When the hot water supply terminal (not shown) of the hot water heater WH is opened and the hot water flow rate of the heat exchanger 11 detected by the flow sensor Sa exceeds a predetermined minimum operating flow rate, requiring the burner unit 2 to be driven for combustion, the control unit 5 starts driving the fan 1 (S1: YES, S2). The control unit 5 also sets the driving speed of the fan 1 to a predetermined speed SPa, which is within the first driving speed range SR1, and opens the main valve V2 for supplying fuel gas to the premixer A (S3). This causes a mixture of fuel gas and air to be generated in the premixer A. For example, as shown in FIG. 7, the speed SPa of the fan 1 is set to a speed equal to or greater than the maximum speed within a specific speed range SR1a within the first driving speed range SR1. Under these conditions, an ignition operation (standard ignition operation) is performed in which the ignition device 22 is turned on (S4).

[0052] When the above-mentioned standard ignition operation causes the mixture to ignite and the combustion flame is detected by the control unit 5 via the flame detection sensor 23, drive combustion control of the burner unit 2 (such as control of the combustion power) is then performed (S5: YES, S6). In the standard ignition operation described above, the fan 1 is driven at speed SPa, and the flapper 5 of the premixing device A is in the open state, as shown in FIG. 5 . Therefore, air flows through both the first and second flow paths 3a and 3b, and this air is mixed with fuel gas flowing from both the first and second fuel gas outlets 80a and 80b. This allows a large amount of air-fuel mixture with an air-fuel ratio suitable for normal driving combustion in the burner unit 2 to be generated and supplied to the burner unit 2. Therefore, igniting the air-fuel mixture using the standard ignition operation described above allows for immediate driving combustion with high combustion power, which is advantageous in shortening the time required to heat water to the target hot water temperature. For example, if a second hot water supply operation is immediately resumed after the completion of one hot water supply operation, the hot water temperature can be quickly restored to the original hot water temperature during the second operation, thereby helping to prevent so-called undershooting of the hot water temperature. Furthermore, scavenging during the interval period, described below, also helps to prevent undershooting.

[0053] The burner unit 2 drive combustion control ends when the hot water supply terminal is closed, causing the hot water flow rate of the heat exchanger 11 to fall below a predetermined minimum operating flow rate, making it necessary to stop the burner unit 2 drive combustion (S7: YES). In this case, the fuel gas main valve V2 is closed, and scavenging (post-purge) is performed (S8, S9). Here, scavenging is a process in which air is blown from the fan 1 into the combustion chamber 29 to expel unburned gas and exhaust gas from the combustion chamber 29 to the outside via the exhaust duct 10a.

[0054] Unlike the above, if it is determined in step S5 that the air-fuel mixture has not been ignited, the fuel gas main valve V2 is closed and a predetermined interval is maintained (S5: NO, S10). During this interval, scavenging is performed (S11). This scavenging is efficiently performed with the fan 1 speed increased above the speed SPa during standard ignition operation, and unburned gas and the like are appropriately removed from the combustion chamber 29.

[0055] When the interval period is up, the control unit 5 determines whether the number of times the standard ignition operation has been performed has reached a predetermined first upper limit (for example, six times) (S12: YES, S13). If the first upper limit has not been reached (S13: NO), the process returns to the previous steps S3 and S4 to perform the standard ignition operation again, and if the air-fuel mixture has ignited (S5: YES), the above-mentioned series of steps S6 to S9 is executed. On the other hand, if the air-fuel mixture is not ignited (S5: NO), the previous steps S10 to S13 are executed again. In this way, the standard ignition operation and the operation control such as scavenging during the subsequent interval period are terminated if the air-fuel mixture is ignited, but if not, they are repeatedly executed up to the first upper limit number of times.

[0056] On the other hand, if the number of times the standard ignition operation is performed reaches the first upper limit without igniting the air-fuel mixture, a non-standard ignition operation is then performed (S13: YES, S14, S15). This non-standard ignition operation is an exceptional ignition operation compared to the standard ignition operation that is normally performed. In this non-standard ignition operation, the drive speed of the fan 1 is set to a predetermined speed SPb in the second drive speed range SR2, the fuel gas main valve V2 is opened, and the ignition device is turned on. Here, the speed SPb of the fan 1 is the fastest speed in the second drive speed range SR2, and more preferably, it is set to the boundary speed between the second drive speed range SR2 and the first drive speed range SR1, indicated by the symbol Na in FIG. 7 (the speed immediately before the flapper 5 changes from the closed state to the open state).

[0057] According to the non-standard ignition operation described above, the premixing device A has the flapper 5 in a closed state as shown in FIG. 4. Of the first and second flow paths 3a and 3b, air flows only through the second flow path 3b. This air is mixed with the fuel gas flowing out of the second fuel gas outlet 80b, generating a fuel-rich mixture with good combustibility (ignitability) that can be supplied to the burner unit 2. The driving speed of the fan 1 is set to speed SPb, which is set to obtain a mixture with the highest CO2 concentration as shown in FIG. 7, which is even more preferable for improving the combustibility (ignitability) of the mixture. Therefore, even if the mixture has not been ignited by the previous standard ignition operation, the non-standard ignition operation can significantly increase the possibility of igniting the mixture. If the non-standard ignition operation results in ignition of the air-fuel mixture (S16: YES), the process then proceeds to the series of steps S6 to S9 described above.

[0058] Unlike the above, if it is determined in step S16 that the air-fuel mixture has not been ignited, the control unit 5 determines whether the number of times the non-standard ignition operation has been performed has reached a predetermined second upper limit (e.g., three times) (S16: NO, S17). If the number of times the non-standard ignition operation has been performed has not reached the second upper limit, the non-standard ignition operation is performed again. However, as a prerequisite for this, the fuel gas main valve V2 is closed and a predetermined interval period is ensured (S17: NO, S20). During this interval period, scavenging is performed with the fan 1 speed increased to a value higher than the speeds SPa and SPb (S21). When the interval period expires, the non-standard ignition operation is performed again (S22: YES, S14 to S15). If the air-fuel mixture is ignited by the re-execution of the non-standard ignition operation (S16: YES), the process then proceeds to the series of steps S6 to S9 described above.

[0059] On the other hand, if the air-fuel mixture is not ignited even after the non-standard ignition operation is re-executed, the previous steps S20 to S15 are executed again. Here, if the number of times the non-standard ignition operation is executed reaches the second upper limit number of times without the air-fuel mixture being ignited, the control unit 5 determines that an abnormality has occurred in the combustion device C or the hot water device WH, and issues an alarm by generating sound using the remote control or the like and displaying an alarm on the screen (S17: YES, S18). The fuel gas main valve V2 is closed, and this closed state is maintained, and subsequent execution of a new ignition operation is prohibited (S18). The fan 1 continues to operate at an increased speed, and scavenging is performed for a predetermined time (S19).

[0060] FIG. 9 shows an example of a control mode for determining whether or not there is an abnormality in the ignition device 22, the fan 1, and the control unit 5 when the air-fuel mixture is not ignited at all, among the above-mentioned operational procedures executed in the combustion device C. In the figure, the ignition operations indicated by symbols N1 to N6 are standard ignition operations performed when the fan 1 is set to speed SPa. In contrast, the ignition operations indicated by symbols N7 to N9 are non-standard ignition operations performed when the fan 1 is set to speed SPb (which is slower than speed SPa by ΔSP in the figure). If the air-fuel mixture has not ignited at the end of the non-standard ignition operation indicated by symbol N9 (time ta), the control unit 5 determines that an abnormality has occurred at that time.

[0061] 9, predetermined operational controls each including three ignition operations N1 to N3, N4 to N6, and N7 to N9 are grouped as group G (G1 to G3), and the basic operational controls of the ignition device 22 and the fan 1 are standardized and repeated. This configuration is preferable in terms of simplifying the control software and ensuring accurate operational control of each part.

[0062] The combustion device C and the water heating device WH of this embodiment can also be configured to execute control as shown in FIG. 10 instead of that shown in FIG. That is, in Figure 10, when the standard ignition operations N1 to N6 are executed sequentially, the driving speed of the fan 1 during these operations gradually increases by appropriate speed increments Δ1 to Δ5 (in Figure 9 above, the driving speed of the fan 1 during the execution of the standard ignition operations N1 to N6 is constant at speed SPa).

[0063] According to the control shown in FIG. 10, the following effects are obtained. That is, if wind blows continuously into the exhaust port 10b of the exhaust duct 10a from the outside while the standard ignition operation is being performed, the air-fuel mixture may not be ignited no matter how many times the standard ignition operation is repeated. In contrast, according to the control shown in Fig. 10, the driving speed of the fan 1 is gradually increased each time the standard ignition operation is repeated, which has the effect of counteracting the wind blowing in, thereby improving the ignition of the air-fuel mixture.

[0064] The combustion device C and the hot water device WH of this embodiment can also be configured to execute an operational control as shown in FIG. 11 instead of the series of operational controls shown in FIG. 8, as will be described below.

[0065] In Figure 11, steps S1 and S2 are the same as those in Figure 8. In the next step S2a, the control unit 5 determines whether or not a "specific ignition operation mode" has been selected and set as the operation mode of the combustion device C. Here, the specific ignition operation mode is a mode that is set when it is known in advance that emergency gas, for example, a mixture of approximately 50% LPG and 50% air, will be used as the fuel gas, and is a mode for immediately executing a non-standard ignition operation by omitting the standard ignition operation. This mode can be set, for example, by a user operating the operation switch 51 of the remote control 5A. The operation switch 51 corresponds to an example of the setting means referred to in the present invention, but the mode can also be set by means other than the operation switch 51. If the specific ignition operation mode is not set (S2a: NO), the process then proceeds to step S3, where the normal series of operation controls described with reference to FIG. 8 are executed. On the other hand, if the specific ignition operation mode is set (S2a: YES), the process then proceeds to step S3, where the normal series of operation controls described with reference to FIG. 8 are executed. The process immediately proceeds to step S14, the standard ignition operation is not performed, and the non-standard ignition operation is immediately performed.

[0066] According to the above-described operational control, when it is known in advance that emergency gas that is difficult to ignite will be used as fuel gas, the standard ignition operation for this emergency gas is not performed unnecessarily, and the non-standard ignition operation is performed immediately, thereby shortening the time required to ignite the emergency gas and enabling early start of combustion drive of the burner unit 2.

[0067] 12 shows another embodiment of the present invention, in which elements that are the same as or similar to those in the previous embodiment are given the same reference numerals as in the previous embodiment, and redundant explanations will be omitted.

[0068] The hot water device WHa in FIG. 12 can be used as a heat source for hot water heating in addition to its general hot water supply function. The hot water supply piping section Ba of this hot water apparatus WHa is connected to a hot water heating appliance (not shown) and has a return port 76a and an inlet port 76b for sending and receiving hot water (including antifreeze) for heating between the hot water heating appliance and the hot water heating appliance. A pump P, an additional heat exchanger HE, and a flow path switching valve V4 are connected to the heat exchanger 11, forming a hot water circulation path 75 that allows hot water sent to the heat exchanger 11 by the pump P and heated to circulate via the additional heat exchanger HE. In this hot water apparatus WHa, hot water for heating, which enters the return port 76a by the operation of the pump P, is sent to the heat exchanger 11 and heated, and then directed to the inlet port 76b via the flow path switching valve V4 and returned to the hot water heating appliance. The general hot water supply function is realized by a configuration in which hot water entering the water inlet port 73 is sent to the additional heat exchanger HE, heated, and then reaches the hot water outlet port 74. As can be seen from this embodiment, the hot water device according to the present invention is not limited to a device for general hot water supply, but can also be configured as a device for hot water heating, and of course, can also be configured as a device for supplying hot water to a bath (for bath reheating).

[0069] The present invention is not limited to the above-described embodiment, and the specific configurations of the combustion device and the hot water device equipped therewith according to the present invention can be freely modified in various ways within the intended scope of the present invention.

[0070] The specific type of fan is not important as long as it has a variable speed. The premixing device includes a gas flow path through which air flows by driving a fan, a fuel gas outlet through which fuel gas flows out by negative pressure generated when air flows through the gas flow path, and a flapper that opens and closes a part of the gas flow path, but the specific shape, size, material, etc. of each of these parts are not limited. The first and second upper limit numbers are not limited to specific values, and each can be set to one time, for example.

[0071] Typical examples of fuel gases include natural gas and LP gas, but the invention is not limited to these and can be applied to various types of fuel gases, such as the emergency gases mentioned above (for example, a mixture of LP gas and air at approximately 50% each). The combustion apparatus according to the present invention is not limited to a water heater, but can also be used for other purposes such as heating, incineration, etc. Furthermore, it is not limited to a type in which the combustion gas flows downward, but can also be a type in which the combustion gas flows upward, for example. [Explanation of symbols]

[0072] A Premixer C. Combustion device WH,WHa Water heating device 1 fan 22 Ignition system 29 Combustion chamber 3 Gas flow path (premixer) 3a First flow path (part of the gas flow path) 5. Flapper (premixer) 51 Operation switch (setting means) 80a, 80b First and second fuel gas outlets (fuel gas outlets of the premixing device)

Claims

1. Variable speed fans and a premixing device having a gas flow path through which air flows by driving the fan, and a fuel gas outlet communicating with the gas flow path, wherein negative pressure generated when the air flows through the gas flow path causes fuel gas to flow out from the fuel gas outlet into the gas flow path, thereby generating a mixture of the air and the fuel gas; a combustion chamber located on an exhaust side of the fan to receive the air-fuel mixture and to combust the air-fuel mixture; an ignition device capable of igniting the air-fuel mixture in the combustion chamber; It is equipped with The premixing device is provided with a flapper capable of opening and closing a part of the gas flow path, and the opening degree of the flapper is larger when the driving speed of the fan is high than when the driving speed is low, The ignition operation of the ignition device to the air-fuel mixture is A combustion device characterized in that, in principle, a standard ignition operation is performed in a first driving speed range of the fan in which the flapper is in an open state, and if this standard ignition operation does not cause the mixture to ignite, then, as an exception, a non-standard ignition operation is performed in a second driving speed range of the fan in which the flapper is in a closed state.

2. The combustion device according to claim 1, The combustion device is configured to perform the non-standard ignition operation with the fan set to the highest speed range of the second driving speed range.

3. The combustion device according to claim 1, the first drive speed range includes a specific speed range in which the flapper is in a partially open state, The combustion device is configured to perform the standard ignition operation with the fan drive speed set to the fastest range of the specific speed range or a speed range equal to or higher than the fastest range.

4. The combustion device according to claim 1, a combustion device configured such that, when an ignition operation of the mixture is performed, the standard ignition operation is performed a number of times equal to or less than a predetermined first upper limit number of times until the mixture ignites, and if the standard ignition operation has been performed the first upper limit number of times but the mixture does not ignite, the non-standard ignition operation is then performed.

5. The combustion device according to claim 4, The combustion device is configured such that, when the standard ignition operation is repeatedly performed multiple times, the driving speed of the fan gradually increases.

6. The combustion device according to claim 1, If the non-standard ignition operation has been repeatedly performed a predetermined second upper limit number of times but the mixture does not ignite, it is determined that an abnormality has occurred, and the ignition operation is not subsequently performed continuously.

7. The combustion device according to claim 1, When the standard ignition operation and / or the non-standard ignition operation is / are repeatedly performed, an interval period is ensured, and during the interval period, the fan is driven at a speed higher than the driving speed during the standard ignition operation and the non-standard ignition operation, The combustion device is configured to perform the scavenging process.

8. The combustion device according to claim 1, a setting means for selecting and setting a specific ignition operation mode as an ignition operation for the air-fuel mixture; a combustion device configured such that, when the specific ignition operation mode is set in the setting means, the standard ignition operation is omitted and the non-standard ignition operation is performed when igniting the air-fuel mixture.

9. A combustion device; a heat exchanger capable of heating water using the combustion gas generated by the combustion device; A hot water device comprising: A water heating system, characterized in that the combustion device according to any one of claims 1 to 8 is used as the combustion device.

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