JP6051778B2 - Combustion device and water heater - Google Patents

Description

  The present invention relates to a combustion apparatus and a water heater.

  A water heater takes in ambient air through an air supply port provided on the exterior of the water heater, and exhausts the exhaust gas after combustion to the outside. However, exhaust gas is taken in from the air supply port due to the influence of the installation environment and wind. Sometimes. This is called self-exhaust recycling (short cycle).

  In such a situation, since the oxygen concentration in the air is low, the combustion state deteriorates. The hot water heater is equipped with a safety function for detecting the low oxygen concentration state by the flame rod and stopping the operation by utilizing the characteristic that the flame easily lifts when the combustion state deteriorates. Combustion devices that detect a low oxygen concentration state by a flame rod and stop operation are disclosed in, for example, Japanese Patent Application Laid-Open No. 2-330618 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2009-162442 (Patent Document 2). Yes. A combustion apparatus that stops combustion when it is determined by the controller to be a short cycle is disclosed in Japanese Patent Laid-Open No. 2000-240940 (Patent Document 3).

JP-A-2-306018 JP 2009-162442 A JP 2000-240940 A

  On the other hand, a combustion apparatus is also required to have a performance that makes it difficult for a flame to easily lift due to a request to cope with a component variation of a fuel-air mixture (air mixture) or a request for noise reduction. In such a combustion apparatus, although the oxygen concentration in the supply air is reduced due to the short cycle, the flame is not easily lifted, so that the frame rod may continue to detect the flame. This condition is particularly likely to occur during continuous combustion. In this case, there is a problem that the combustion does not stop because the flame rod continues to detect the flame even though the oxygen concentration in the supply air is reduced due to the short cycle.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a combustion apparatus capable of continuing stable combustion even when the oxygen concentration in the supply air is reduced, and capable of reliably detecting self-exhaust recycling. It is to provide a water heater.

  The combustion apparatus of the present invention includes a burner, an ignition device for igniting the burner, a frame rod for detecting a flame generated in the burner, and a control unit for controlling the flame generated in the burner. Yes. When it is detected by the flame rod that the burner has continuously generated a flame for a predetermined time, the control unit controls to extinguish the flame generated by the burner and perform a reignition operation by the ignition device after extinguishing.

  According to the combustion apparatus of the present invention, when the burner generates a flame continuously for a predetermined time, the flame generated in the burner is extinguished, and the reignition operation is automatically performed by the ignition device after extinguishing the fire. In a state where the oxygen concentration in the supply air is low due to the short cycle, the oxygen concentration in the air-fuel mixture that has taken in air with a low oxygen concentration is also low. In the combustion apparatus, a stable flame is formed at the time of ignition, so that the ratio of the fuel in the air-fuel mixture is set higher than that at the time of continuous combustion. That is, the oxygen concentration in the air-fuel mixture is set to be lower at the time of ignition than at the time of continuous combustion. Therefore, when the oxygen concentration in the supply air is low due to the short cycle, the oxygen concentration in the air-fuel mixture at the time of ignition becomes lower than the oxygen concentration necessary for combustion. As a result, the amount of oxygen necessary for combustion cannot be ensured, so that a flame cannot be generated. In the combustion apparatus of the present invention, the flame generated in the burner is extinguished when the burner generates a flame continuously for a predetermined time, and after the fire is extinguished, a reignition operation is automatically performed by the ignition device. Even if the oxygen concentration is lowered, stable combustion can be continued and self-exhaust gas recycle can be reliably detected.

  According to the combustion apparatus described above, the control unit shortens the time until the flame generated in the burner is extinguished as the generated heat amount increases based on the integrated value of the generated heat amount when the flame is continuously generated. Control as follows. A decrease in the oxygen concentration can be estimated based on the integrated value of the amount of heat generated when the flame is continuously generated. For this reason, the flame can be extinguished in accordance with the decrease in oxygen concentration by shortening the time until the flame generated in the burner is extinguished as the amount of generated heat increases.

  According to the above combustion apparatus, the fuel ratio of the air-fuel mixture supplied to the burner during the reignition operation is set higher than the fuel ratio of the air-fuel mixture supplied to the burner during the normal ignition operation. Thereby, since the oxygen concentration in the air-fuel mixture during the reignition operation can be further lowered, it is possible to make it difficult to generate a flame during the reignition. For this reason, when the oxygen concentration in supply air has fallen by the short cycle, safety | security can be improved by making it hard to produce a flame by reignition operation | movement.

  The water heater of the present invention includes any one of the above-described combustion apparatuses and a heat exchanger disposed on the combustion apparatus. According to the water heater of the present invention, since any one of the above-described combustion devices is provided, stable combustion can be continued even if the oxygen concentration in the supply air is reduced, and self-exhaust recycling is ensured. Can be detected.

  As described above, according to the present invention, it is possible to realize a combustion apparatus and a water heater that can continue stable combustion even when the oxygen concentration in the supply air decreases and can reliably detect self-exhaust recycling.

It is a perspective view which shows roughly the structure of the principal part of the water heater in one embodiment of this invention. It is a partially broken schematic side view which abbreviate | omits and shows a heat exchanger from the water heater of FIG. It is a perspective view which shows roughly the structure of the combustion apparatus in one embodiment of this invention used for the water heater of FIG. 1, Comprising: It is a disassembled perspective view which removes and shows the wall surface of a burner case. FIG. 4 is an exploded perspective view schematically showing the configuration of the combustion apparatus shown in FIG. 3. It is a perspective view which shows roughly the structure of the light / dark burner in one embodiment of this invention used for the combustion apparatus shown to FIG. FIG. 6 is an exploded perspective view schematically showing the configuration of the light and dark burner shown in FIG. 5. It is a schematic sectional drawing which follows the VII-VII line of FIG. It is a schematic plan view of the combustion apparatus which shows the mode of arrangement | positioning of the flame rod of the combustion apparatus in one embodiment of this invention. It is a figure which shows schematically the structure provided with the control part of the water heater in one embodiment of this invention. It is a figure which shows schematically the structure of the valve shown in FIG. It is a figure which shows schematically the structure provided with piping of the water heater in one embodiment of this invention. It is a flowchart which shows operation | movement of the combustion apparatus in one embodiment of this invention. It is a figure which shows the relationship between the air ratio of the rich gas at the time of operating the combustion apparatus in one embodiment of this invention, the oxygen concentration in supply air, and time. It is a figure which shows the relationship between the emitted-heat amount at the time of driving | running the combustion apparatus in one embodiment of this invention, and time. It is a figure which shows the relationship between the air ratio of the rich gas at the time of driving | running the combustion apparatus when the short cycle has not generate | occur | produced, the oxygen concentration in supply air, and time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
First, the structure of the water heater in one embodiment of the present invention will be described. The water heater in one embodiment of the present invention has a combustion device in which the flame is difficult to lift even if the oxygen concentration in the supply air decreases.

  With reference to FIG. 1 and FIG. 2, the water heater 1 of one embodiment of this invention has mainly the combustion apparatus 2, the ventilation part 3, and the heat exchanger 4. FIG. The combustion device 2 is for generating a flame by burning gas. The air blowing unit 3 is for supplying combustion air to the combustion device 2 and includes, for example, a fan, a fan case, a fan motor, and the like. The heat exchanger 4 is disposed at the upper part of the combustion device 2 and is used to exchange heat between the refrigerant (hot water) in the pipe and the combustion gas generated in the combustion device 2.

  In this embodiment, a combustion apparatus using gas as fuel will be described. However, the fuel is not limited to gas, and liquid fuel such as vaporized petroleum may be used.

  Referring to FIGS. 3 and 4, combustion device 2 mainly includes burner case 11, a plurality of burners 12, an ignition device (ignition plug) 13, and a frame rod 14.

  The burner case 11 has a hole 11a for taking in air from the blower 3 into the bottom plate. The burner case 11 has a partition plate 11b for partitioning the air passage from the hole 11a and the storage portion of the burner 12. The partition plate 11b is provided with a plurality of through holes 11c. The through holes 11c connect the air passages that enter the burner case 11 from the holes 11a and the storage portions of the plurality of burners 12.

  Each of the plurality of burners 12 is supported by the partition plate 11 b and stored in the burner case 11. The gas inlets 21 a and 21 b of each of the plurality of burners 12 are connected to openings 11 d and 11 e provided on the wall surface of the burner case 11, respectively.

  A spark plug 13 and a frame rod 14 are disposed above the plurality of burners 12. Each of the spark plug 13 and the frame rod 14 is attached to the wall surface 11 </ b> B of the burner case 11.

  The spark plug 13 is for igniting the burner 12. Specifically, the spark plug 13 generates a spark in the fuel-air mixture (air mixture) ejected from the burner 12 by generating an ignition spark with a target provided in the burner 12. belongs to. The flame rod 14 applies an alternating voltage between the flames generated in the burner 12 and uses a conductivity and rectification action due to the ionization of the flame to generate a direct current (hereinafter referred to as flame current) flowing from the flame rod 14 to the flame. It is for detecting the presence or absence of a flame by detecting.

5 and 6, each of the plurality of burners 12 is a so-called light and dark burner. The lean burner burns a fuel-air mixture (hereinafter, referred to as “pure gas”) having a fuel that is leaner than an air ratio 1 and a fuel-air mixture (hereinafter, referred to as a “rich gas”) that is richer in fuel than the air ratio 1. It means NO _X burner.

  The light and dark burner 12 mainly includes a main body unit 21, a pair of left and right side dark burner units 22a and 22b, a central dark burner unit 23, and a pair of right and left light burner units 24a and 24b.

  The main unit 21 is provided with a gas inlet 21a for light gas and a gas inlet 21b for concentrated gas. The gas inlet 21 a for the light gas communicates with a light gas passage 21 c in the main unit 21. The rich gas inlet 21 b communicates with a rich gas passage 21 d in the main unit 21. A pair of openings 21e and 21e are provided on the left and right of the main unit 21 so as to communicate with the concentrated gas passage 21d.

  A pair of side dark burner units 22a and 22b are attached to each of the left and right sides of the main unit 21 so as to cover the opening 21e. Thereby, the space between the outer wall of the main unit 21 and the inner walls of the side rich burner units 22a and 22b serves as a passage for the rich gas. That is, after the rich gas supplied from the rich gas inlet 21b enters the rich gas passage 21d, each of the outer wall of the main unit 21 and the side rich burner units 22a and 22b from the pair of left and right openings 21e and 21e. It enters the space between the inner walls and is ejected from the end rich flame holes 22aa and 22ba.

  The central concentrated burner unit 23 has a concentrated gas passage insertion portion 23b at the lower end, and an opening 23c leading to the internal passage is formed in the concentrated gas passage insertion portion 23b. The central concentrated burner unit 23 is inserted into the light gas passage 21 c of the main unit 21, whereby the concentrated gas passage insertion portion 23 b provided with the opening 23 c reaches the concentrated gas passage 21 d of the main unit 21. As a result, the concentrated gas that has entered the concentrated gas passage 21d from the gas inlet 21b enters the internal passage of the central concentrated burner unit 23 through the opening 23c, and is ejected from the concentrated flame hole 23a of the central concentrated burner unit 23.

  A pair of light burner units 24 a and 24 b are inserted into the light gas passage 21 c of the main unit 21. Each of the pair of light burner units 24a and 24b is located on the left and right of the central dark burner unit 23 in the light gas passage 21c. As a result, the light gas that has reached the light gas passage 21c from the light gas inlet 21a enters the internal passages of the light burner units 24a and 24b from the lower ends of the pair of light burner units 24a and 24b. It is ejected from each of the pale flame holes 24aa and 24ba of 24b.

  With reference to FIG. 7, from the above, a rich flame is formed at the end rich flame hole 22aa between the outer wall of the main unit 21 and the inner wall of the side rich burner unit 22a. A rich flame is formed at the end rich flame hole portion 22ba between the inner wall of the burner unit 22b. Further, a rich flame is formed at the rich flame hole 23 a of the central rich burner unit 23. Further, a light flame is formed in each light flame hole 24aa, 24ba of the light burner unit 24a, 24b. That is, the rich burner 12 is arranged along the width direction W in the order of end rich flame hole portion 22aa-light flame hole portion 24aa-center rich flame hole portion 23a-light flame hole portion 24ba-end rich flame hole portion 22ba. It has a flame hole part arranged.

  With reference to FIG. 2, in this water heater 1, the air around the water heater 1 is taken in from the side of the air blower 3 and is burner through a hole 11 a provided in the bottom plate of the burner case 11 of the combustion device 2. Enter case 11. Part of the air that has entered the burner case 11 is supplied into the burner 12 together with the fuel gas from each of the gas inlets 21a and 21b of the plurality of burners 12 arranged in the burner case 11 as primary air. . Further, the remaining portion of the air that has entered the burner case 11 is supplied as secondary air to the storage portion of the burner 12 from a through hole 11 c provided in the partition plate 11 b that partitions the air passage and the storage portion of the burner 12. The

  Referring to FIG. 7, since secondary air is supplied as described above, the outer side in the width direction of light and dark burner 12 serves as a passage for secondary air. Since the central rich burner unit 23 and the pair of light burner units 24a and 24b are inserted into the light gas passage 21c of the main unit 21, the space between the light flame hole portion 24aa and the center rich flame hole portion 23a. And it is comprised so that secondary air may not flow between the pale flame hole part 24ba and the center rich flame hole part 23a. Further, the secondary air does not flow between the pale flame hole portion 24aa and the end rich flame hole portion 22aa and between the pale flame hole portion 24ba and the end rich flame hole portion 22ba.

  Referring to FIG. 8, a plurality of light and dark burners 12 are arranged along the width direction W. As a result, the arrangement of the flame holes of each dark and light burner 12 (end rich flame hole 22aa-palm flame hole 24aa-central rich flame hole 23a-palm flame hole 24ba-end rich flame hole 22ba) It is repeated along the width direction W. Between the plurality of light and dark burners 12, a secondary air passage for allowing secondary air to pass through is disposed.

  Each of the spark plug 13 and the frame rod 14 is attached to a wall surface 11B extending along the width direction W of the burner case 11, and projects from the wall surface 11B directly above a region where the plurality of light and dark burners 12 are arranged. It extends. The tip of the frame rod 14 is bent, for example, in a direction along the wall surface 11B to which the frame rod 14 is attached (for example, a direction substantially parallel to the wall surface 11B).

  The portion of the frame rod 14 located immediately above the arrangement area of the plurality of light and dark burners 12 is arranged so as to avoid directly above the central rich flame hole portion 23a, and the end rich flame hole portion 22aa and the second end portion. It is located directly above at least one of the rich flame hole 22ba, the pale flame hole 24aa and the pale flame hole 24ba. Here, “directly above the central concentrated flame hole 23a” means directly above the plurality of concentrated gas jets forming the central concentrated flame hole 23a.

  In the present embodiment, the portion of the frame rod 14 (particularly the portion extending in parallel with the wall surface 11B) positioned immediately above the arrangement region of the plurality of light and dark burners 12 is, for example, the central darkness of one light and dark burner 12 adjacent to each other. It is located directly above the region sandwiched between the flame hole portion 23a and the central deep flame hole portion 23a of the other light and dark burner 12. The frame rod 14 is positioned directly above each of the end rich flame hole portion 22aa, the second end rich flame hole portion 22ba, the pale flame hole portion 24aa, the pale flame hole portion 24ba, and the secondary air passage portion. Yes. That is, the portion of the frame rod 14 that is located immediately above the arrangement region of the plurality of dark and light burners 12 includes the end rich flame hole portion 22aa, the second end rich flame hole portion 22ba, the pale flame hole portion 24aa, and the pale flame hole portion. It is located right above the outlet of each gas of 24ba and right above the secondary air passage.

The end rich flame hole portion 22aa is a plurality of deep flame hole holes (jet ports) 22aa ₁ , 22aa ₂ , 22aa ₃ ,... Arranged along the direction intersecting the wall surface 11B to which the frame rod 14 is attached. have. Further, the end rich flame hole portion 22ba has a plurality of deep flame hole holes (jet ports) 22ba ₁ , 22ba ₂ , 22ba ₃ , which are arranged along the direction intersecting the wall surface 11B to which the frame rod 14 is attached. …have.

Flame rod 14, the plurality of end portions of concentrated fire hole portion 22aa of concentrated fire hole hole portions 22aa _1, 22aa _2, 22aa _3, ... dark flame hole hole portions 22aa ₁ closest to the wall surface 11B of the It is preferable that it is located right above. The flame rod 14, a plurality of concentrated fire hole hole of the end cone fire hole portion _{22ba 22ba 1, 22ba 2, 22ba} 3, ... concentrated fire hole hole portions 22ba ₁ closest to the wall surface 11B of the It is preferable that it is located just above.

  Then, with reference to FIG. 9 and FIG. 10, the structure provided with the control part 30 of the water heater 1 of one embodiment of this invention is demonstrated. The combustion device 2 of the water heater 1 has a control unit 30. The control unit 30 is for controlling the flame generated in the burner 12. The control unit 30 is composed of, for example, a microcomputer and a hybrid integrated circuit (HIC). The control unit 30 is configured to be able to detect a continuous operation for a predetermined time. The control unit 30 is connected to the blower unit 3, the spark plug 13, the frame rod 14, and the valve 32. The control unit 30 is configured to be able to control the rotational speed of the fan of the blower unit 3, the presence or absence of ignition of the spark plug 13, and the opening of the valve 32.

  The control unit 30 is configured to increase the rotational speed of the fan of the blower unit 3 to blow combustion air to the burner 12 and to open the valve 32 to supply the air-fuel mixture containing the fuel 31 to the burner 12. And the control part 30 is comprised so that the ignition plug 13 can be ignited. As a result, the air-fuel mixture burns and a flame is generated in the burner 12. This flame is detected by the frame rod 14. The control unit 30 is configured to extinguish a flame generated in the burner 12 by closing the valve 32 and stopping the supply of the fuel 31 to the burner 12.

  The control unit 30 extinguishes the flame generated in the burner 12 when the flame rod 12 detects that the burner 12 continuously generates a flame for a predetermined time, and automatically reignites the ignition plug 13 after extinguishing the fire. It is configured to be controllable to perform operations. The reignition operation is automatically performed by the control unit 30. The reignition operation is performed, for example, within 1 second after extinguishing the fire. The reignition operation may be performed while the tapping temperature does not drop. Further, the reignition operation may be performed while the oxygen concentration in the supply air does not change.

  The valve 32 is configured to be able to supply and stop the air-fuel mixture including the fuel 31 to the burner 12. As shown in FIG. 10, the valve 32 includes a main valve 32a, a proportional valve 32b, and a plurality of burner side valves 32c. The main valve 32a is connected to the proportional valve 32b so that the fuel 31 can be supplied to and stopped from the burner 12. The proportional valve 32b is connected to a plurality of burner side valves 32c. The plurality of burner side valves 32 c are connected to the plurality of burners 12, respectively.

  Furthermore, with reference to FIG. 11, the structure provided with piping of the water heater 1 of one embodiment of this invention is demonstrated. The water heater 1 includes a water supply pipe 41, a hot water supply pipe 42, a water supply sensor 43, and a hot water sensor 44. The heat exchanger 4 is connected to a water supply pipe 41 for supplying water to the heat exchanger 4 and a hot water supply pipe 42 for discharging hot water from the heat exchanger 4.

  A water supply sensor 43 for measuring the heat quantity of the water supply is attached to the water supply pipe 41. A hot water sensor 44 for measuring the amount of heat of the hot water is attached to the hot water piping 42. The water supply sensor 43 and the hot water sensor 44 are connected to the control unit 30. The difference between the calorific value of the hot water measured by the hot water sensor 44 and the calorific value of the feed water measured by the feed water sensor 43 is the generated heat amount, and the product of this generated heat amount and time is the integrated value of the generated heat amount. The control unit 30 is configured to be able to measure the amount of generated heat and its integrated value.

  Moreover, the water heater 1 may be arrange | positioned in the space enclosed by the corrugated board enclosure 50. FIG. Although this space is not sealed and the air in the space is ventilated, the exhaust gas discharged from the water heater 1 is easily taken in from the air supply port because it is surrounded by the corrugated plate enclosure 50. That is, a short cycle is likely to occur in such a situation.

Next, operation | movement of the combustion apparatus 2 of the water heater 1 in one embodiment of this invention is demonstrated.
Referring to FIGS. 9 and 12, first, operation of combustion device 2 of water heater 1 is started (step S1). It is determined whether or not there is a continuous operation for a predetermined time from the start of the operation (step S2). This predetermined time can be set in advance. For example, the predetermined time may be 900 seconds. This predetermined time can be changed in accordance with the amount of heat generated.

  If the operation is continued for a predetermined time, the flame generated in the burner 12 is extinguished (step S3). Specifically, the supply of the fuel 31 is stopped by controlling the control unit 30 to close the valve 32, and the blower to the burner 12 is controlled by controlling the control unit 30 to stop the operation of the blower unit 3. Is stopped. In this way, the flame generated in the burner 12 is extinguished. On the other hand, if the vehicle is not operated continuously for a predetermined time, the operation is continued.

  After the flame generated in the burner 12 is extinguished, the control unit 30 automatically controls the ignition plug 13 to ignite so that the reignition operation is performed (step S4). When combustion occurs due to the reignition operation, it is determined again whether or not there is a continuous operation for a predetermined time (step S2). On the other hand, when combustion does not occur due to the reignition operation, the operation of the water heater 1 is stopped, and the user is notified of the abnormality through a remote controller (not shown) (step S6). Before notifying that it is abnormal, wait for a predetermined time (for example, the time until the oxygen concentration rises to the concentration necessary for combustion), and perform a re-ignition operation to cause a temporary combustion failure Abnormality notification can be eliminated and abnormality can be detected more accurately. In this way, self-exhaust recycle can be detected by not reigniting when the oxygen concentration in the supply air is reduced due to the short cycle. Further, when the oxygen concentration in the supply air is reduced due to a short cycle, combustion can be stopped without detecting a flame lift.

  Next, the relationship between the air ratio of the air-fuel mixture and the oxygen concentration in the supply air will be described with reference to FIG. Since the rich gas is ignited at the time of ignition, the air ratio of the rich gas will be described. The air ratio of the rich gas is set to be lower than that during continuous combustion in order to form a stable flame during ignition. Then, the air ratio of the rich gas increases during continuous combustion compared to during ignition. However, the occurrence of a short cycle during continuous combustion reduces the oxygen concentration in the supply air. And the air ratio of rich gas also falls by taking in the air with which oxygen concentration fell.

  After continuously fueling for a predetermined time, the flame once generated in the burner is extinguished. Although it is automatically reignited by the ignition device after extinguishing the fire, the air ratio of the concentrated gas is set to be lower than that during continuous combustion in order to form a stable flame even during reignition. Therefore, during reignition, the air ratio of the rich gas is lower than the ignition limit air ratio, as indicated by P1 in FIG. For this reason, the rich gas cannot be reignited in this state.

  In one embodiment of the present invention, the fuel ratio of the air-fuel mixture supplied to the burner 12 during the reignition operation is set higher than the fuel ratio of the air-fuel mixture supplied to the burner 12 during the normal ignition operation. That is, the air ratio of the rich gas is set lower during the reignition operation than during the normal ignition operation. For this reason, during the reignition operation, it becomes more difficult to ignite the rich gas. Note that the air ratio of the concentrated gas can be lowered by reducing the rotational speed of the fan of the blower 3 from, for example, 1000 rpm to 800 rpm.

  Moreover, with reference to FIG. 14, the control part 30 may control the time until fire extinguishing according to the emitted-heat amount. That is, the control unit 30 performs control so that the time until the flame generated in the burner 12 is extinguished becomes shorter as the generated heat amount increases based on the integrated value of the generated heat amount when the flame is continuously generated. Also good. As shown in FIG. 14, in the combustion pattern A, the integrated value of the generated heat amount reaches a predetermined value in a shorter time than the combustion pattern B. Therefore, the control unit 30 controls the combustion pattern A so that the time until extinction is shorter than the combustion pattern B.

  Next, the operation and effect of the present embodiment will be described in comparison with the case where the short cycle shown in FIG. 15 does not occur.

  Referring to FIG. 15, when the self-exhaust gas recycle (short cycle) has not occurred, the oxygen concentration in the supply air is constant. In this case, since the exhaust gas is not taken in from the air supply port, the air ratio of the rich gas during the reignition operation does not become lower than the air ratio at the ignition limit. Therefore, the rich gas can be reignited. Note that the air ratio of the concentrated gas during continuous combustion is lower than the theoretical air ratio.

  On the other hand, according to the combustion apparatus 2 of the embodiment of the present invention, when the burner 12 has continuously generated a flame for a predetermined time, the flame generated in the burner 12 is extinguished, and automatically after the extinction. A reignition operation is performed by the spark plug 13. In a state where the oxygen concentration in the supply air is low due to the short cycle, the oxygen concentration in the air-fuel mixture that has taken in air with a low oxygen concentration is also low. Further, in the combustion device 2, in order to form a stable flame at the time of ignition, the ratio of the fuel in the air-fuel mixture is set to be higher than that at the time of continuous combustion. That is, the oxygen concentration in the air-fuel mixture is set to be lower at the time of ignition than at the time of continuous combustion. Therefore, when the oxygen concentration in the supply air is low due to the short cycle, the oxygen concentration in the air-fuel mixture at the time of ignition becomes lower than the oxygen concentration necessary for combustion. As a result, the amount of oxygen necessary for combustion cannot be ensured, so that a flame cannot be generated. In the combustion apparatus 2 according to the embodiment of the present invention, when the burner 12 continuously generates a flame for a predetermined time, the flame generated in the burner 12 is extinguished, and the ignition plug 13 automatically performs a reignition operation after the extinction. By performing the above, stable combustion can be continued even if the oxygen concentration in the supply air decreases, and self-exhaust gas recycle can be reliably detected.

  Moreover, according to the combustion apparatus 2 of one embodiment of the present invention, the control unit 30 is generated in the burner 12 as the generated heat amount increases based on the integrated value of the generated heat amount when the flame is continuously generated. Control the time until the flame is extinguished. A decrease in the oxygen concentration can be estimated based on the integrated value of the amount of heat generated when the flame is continuously generated. For this reason, the flame can be extinguished in accordance with the decrease in oxygen concentration by shortening the time until the flame generated in the burner is extinguished as the amount of generated heat increases.

  Moreover, according to the combustion apparatus 2 of the embodiment of the present invention, the fuel ratio of the air-fuel mixture supplied to the burner 12 during the reignition operation is the fuel ratio of the air-fuel mixture supplied to the burner 12 during the normal ignition operation. Is set higher than. Thereby, since the oxygen concentration in the air-fuel mixture during the reignition operation can be further lowered, it is possible to make it difficult to generate a flame during the reignition. For this reason, when the oxygen concentration in supply air is falling by short cycle, safety can be improved by making it hard to produce a flame by reignition operation.

  A water heater 1 according to an embodiment of the present invention includes any one of the above-described combustion devices 2 and a heat exchanger 4 disposed on the combustion device 2. According to the hot water heater 1 of one embodiment of the present invention, since any one of the combustion devices 2 described above is provided, stable combustion can be continued even if the oxygen concentration in the supply air is reduced. And self-exhaust recycling can be detected reliably.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Hot water heater, 2 Combustion device, 3 Air blower, 4 Heat exchanger, 11 Burner case, 12 Burner, 13 Ignition device, 14 Frame rod, 30 Control part, 31 Fuel, 32 Valve, 41 Water supply piping, 42 Hot water piping, 43 Water supply sensor, 44 Hot water sensor, 50 Corrugated board enclosure.

Claims (4)

With a burner,
An ignition device for igniting the burner;
A frame rod for detecting a flame generated in the burner;
A control unit for controlling the flame generated in the burner,
When it is detected by the frame rod that the burner has continuously generated a flame for a predetermined time, the control unit extinguishes the flame generated by the burner, and after ignition is automatically reignited by the ignition device. Combustion device that controls the operation. With a burner,
An ignition device for igniting the burner;
A frame rod for detecting a flame generated in the burner;
A control unit for controlling the flame generated in the burner,
When it is detected by the frame rod that the burner has continuously produced a flame for a predetermined time, the control unit extinguishes the flame produced by the burner and performs a reignition operation by the ignition device after extinguishing the fire. controlled to, based on the integrated value of the amount of heat generated when that occurs the flame in succession, the time until to extinguish the flame produced by the burner in accordance with the heat generation amount increases to control so that the shorter combustion device . With a burner,
An ignition device for igniting the burner;
A frame rod for detecting a flame generated in the burner;
A control unit for controlling the flame generated in the burner,
When it is detected by the frame rod that the burner has continuously produced a flame for a predetermined time, the control unit extinguishes the flame produced by the burner and performs a reignition operation by the ignition device after extinguishing the fire. Control and
The fuel ratio of the air- fuel mixture supplied to the burner during the re-ignition operation is reduced by reducing the number of rotations of the fan of the blower for supplying combustion air, so that the mixture supplied to the burner during the normal ignition operation is reduced. It is set to be higher than the air-fuel ratio, combustion equipment. The combustion apparatus according to any one of claims 1 to 3,
A water heater comprising a heat exchanger disposed on the combustion device.

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